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V
Pulsed Doppler Echocardiography in Cardiac
Diagnosis
PETER WILDE, BM, MRCP(UK), FRCR
Consultant Cardiac Radiologist) Bristol Royal Infirmary
DAVID 'PITCHER, MB, MRCP(UK)
Consultant Cardiologist, Hereford County Hospital
The Doppler principle allows blood flow to be measured
within the body by the analysis of the altered frequency of
returned ultrasound waves reflected from a moving col-
umn of blood. Pulsed Doppler echocardiography (PDE)
allows sampling of flow at a specific depth within the
patient by appropriate timing in the system[l]. Some
modern ultrasound instruments can combine the PDE
system with a sector scanner so that flow can be sampled
at any selected site within a two-dimensional image[2].
This capability has considerably increased the flexibility
of ultrasound diagnosis in heart disease because a single
diagnostic examination can incorporate the complemen-
tary modalities of two-dimensional (2D), M-mode and
Doppler echocardiography.
The Doppler information is returned initially as an
audio signal which has a characteristic sound in different
situations but, for full analysis, the wave form is com-
puter-processed by the Fourier technique which allows a
graphic display of the frequency components present
within the signals[3]. These frequency components are
closely related to the blood velocity.
The angle between the examining beam and the direc-
tion of flow is particularly important. The most accurate
Doppler information is obtained when the direction of the
examination beam is close to the direction of blood flow.
Turbulent flow can, however, be detected from many
directions because the nature of the flow is multidirec-
tional.
Inspection of the spectrally analysed Doppler signal
together with the two-dimensional image and the simul-
taneous ECG allows several important features of blood
flow to be assessed, namely: (a) site of flow within the
image; (b) direction of flow (towards or away from
transducer); (c) timing of flow (systole or diastole); (d)
changing flow patterns within systole or diastole; (e)
laminar or turbulent flow; (f) unusually high or low
velocity flow, and (g) unusually high or low intensity
signals.
Diagnostic PDE features of normal and abnormal
cardiac blood flow have been reviewed by various
workers[4-8], Grading of severity of many lesions has
also been achieved[6, 9-11],
This article assesses the diagnostic contribution of this
new modality in a busy clinical echocardiography depart-
ment with referrals from both cardiological and non-
cardiological sources.
Methods
Equipment and Techniques
All scans were performed in the Radiology Department of
the Bristol Royal Infirmary on an ATL (Advanced
Technology Laboratories) Mark 600C mechanical sector
scanner with a PDE facility. The PDE 'sample volume'
(region of Doppler examination) was controlled by a
Fig. 1. Suprasternal trace from a normal ascending aorta. The
initial increase in velocity is shown by a thin line which
indicates laminar flow.
\ <
1
0-6
0*3
4
\
'*
. *
ECG
rXZ.<J
U
IIIIIIIIIHIIIl Illl
Ill HI 111 II11 III 111
Journal of the Royal College of Physicians of London Vol. 20 No. 1 January 1986 25
movable marker on a radial line within the image. The
instrument was also capable of recording M-mode traces.
A simultaneous ECG was always recorded.
Adults were studied using a medium focus 3 MHz
transducer and children with a medium focus 5 MHz
transducer. A small non-imaging 3 MHz transducer was
also used when access to the suprasternal notch was
difficult with the larger imaging transducer.
Flow through valves was assessed by positioning the
'sample volume' in line with the flow leaving the valve
orifice. Normal flow through the valves was laminar in
quality and low in velocity. Valvar stenosis was character-
ised by high velocity turbulent flow. The degree of
stenosis was not assessed in this study (Figs 1-5).
Valvar regurgitation was diagnosed by the detection of
high velocity turbulent flow proximal to a closed valve
(Figs 3, 6-8). Severity of regurgitation was assessed by
mapping the regurgitant jet with the movable sample
volume. Low intensity turbulence only detectable near to
the closed valve was graded as mild regurgitation. If
turbulence was detectable up to halfway into the receiving
chamber, moderate regurgitation was recorded. High
intensity turbulence detected throughout most of the
receiving chamber was graded as severe regurgitation. 2-
D and M-mode assessment of the left ventricle was
sometimes an additional help in assessing severity of
regurgitation.
In paediatric cases the sample volume was moved along
the right side of the interventricular septum to detect any
turbulent high velocity flow arising from a ventricular
septal defect[8, 12]. Pulmonary arterial flow was evaluat-
1-8
1-5
0-3i
111 HI 111IIIIIII11 III 111
nmiiiiiiiimmiiHi
llllllllllllllllllllllll
Fig. 2. Suprasternal trace from the ascending aorta of a patient
with aortic stenosis. Turbulent flow is indicated by the multiple
velocities recorded throughout the time of flow. The peak of
velocity is higher than normal and there is a delayed rise to peak
velocity.
Fig. 3. Two-dimensional apical view showing left ventricle
(L V), left atrium (LA), right ventricle (R V), right atrium
(RA) and mitral valve (MV). Two different sample volume
positions are indicated (A and B).
Fig. 4. Normal flow through the mitral valve taken from the
position shown by A in Fig. 3. The two peaks of flow in
diastole indicate passive filling (P) followed by atrial contrac-
tion (A). The flow is laminar and of low velocity.
26 Journal of the Royal College of Physicians of London Vol. 20 No. 1 January 1986
ed to detect diastolic turbulence caused by a patent ductus
arteriosus[13] or systolic high velocity turbulence due to
pulmonary stenosis. The flow in the descending portion
of the aortic arch was assessed in order to detect the high
velocity turbulent flow of coarctation. Valve function was
assessed as described above for adults.
Patients
All patients having a complete cardiac ultrasound exam-
ination in a six-month period were reviewed (Fig. 9).
Thirty patients examined without PDE and 32 patients
with inadequate data were excluded from the series.
The 294 patients comprised 75 catheterised cases and
219 non-catheterised cases. In the catheterised group 32
adults had ultrasound examination and catheterisation
within seven days of each other; 43 paediatric cases had
ultrasound and catheterisation on the same day. In the
latter group ages ranged from five days to 21 years with a
median age of two years. Of the 219 adult patients who
were not catheterised, 125 were referred by cardiologists
and 94 by other clinicians.
2*4 f
1-8
s 1-2
0*6
Fig. 5. -F/ow measured from the mitral valve orifice of a patient
with mitral stenosis. Note the high velocity which decreases
slowly during diastole indicating a persisting valve gradient.
Fig. 6. A trace showing turbulent mitral regurgitation during
systole and laminar mitral flow during diastole. There is a
single phase mitral flow in this case due to the brief duration of
diastole. The recording was made from a position corresponding
to B in Fig. 3. Flow above the baseline is towards the
transducer. The turbulent flow shows aliasing (artefactual
reverse flow) due to its high velocity.
Fig. 7. Two-dimensional apical view (angled up from Fig. 3)
to allow positioning of the sample volume (SV) in the left
ventricular outflow tract (L VOT).
ECG i|
U^n/K
WWSj
1111 in i hi 11 mi ii n 111
\r^Avi
Journal of the Royal College of Physicians of London Vol. 20 No. 1 January 1986 27
Results
Adult Catheterised Patients (32 cases)
Table 1 compares catheterisation (and angiography) with
PDE in the diagnosis of mitral and aortic valve stenosis
and regurgitation.
In only one 'false negative' case of mitral regurgitation
was a lesion of moderate severity missed by PDE. In the
remaining eight 'false negative' and 'false positive' cases
of aortic and mitral regurgitation the discrepancies were
all due to lesions judged by angiogram or PDE to be mild.
No case of regurgitation judged severe by angiography
was missed or considered mild by PDE.
All stenotic lesions were correctly identified.
Paediatric Catheterised Patients (43 cases)
Table 2 shows the diagnosis of simple malformations by
cardiac catheterisation and angiography, compared with
diagnosis by PDE and 2-D techniques. Complex abnor-
malities of connection and situs are not included in this
table.
In no diagnostic category was any false positive diag-
nosis made by PDE.
A number of additional aspects of PDE diagnosis were
apparent on review of these and the other cases in this
group.
(a) PDE techniques are very sensitive in detecting vari-
ations from the normal flow patterns. Mild increased
turbulence and velocity of flow were detected in a variety
of cases where the invasive data showed a mild abnor-
mality to be present. This group included three cases of
surgically corrected coarctation of aorta, one case of post-
operative transposition of the great arteries with mild
obstruction of the superior systemic venous channel, and
one case of mild pulmonary stenosis in transposition of
Table 1. Comparison of cardiac catheterisation and angiography with PDE in the diagnosis of aortic and mitral valve lesions (32
cases).
Total cases with Positive Catheter Diagnosis Negative Catheter Diagnosis
positive catheter Positive PDE Negative PDE Positive PDE Negative PDE
diagnosis diagnosis diagnosis diagnosis diagnosis
Mitral or
aortic stenosis 18 18 0 0 14
Aortic
regurgitation 16 14 2 0 5*
Mitral
regurgitation 19 15 4 3 7**
'Aortography in 21 cases
**Left ventriculography in 29 cases
Fig. 8. A trace showing turbulent aortic regurgitation during
diastole. The sample volume position is shown (SV) in Fig. 7.
There is laminar flow away from the transducer during systole.
There is aliasing due to the high velocity of the diastolic
regurgitant jet.
Review group
Paediatric Adult Cardiology Non-cardiological
referral referral
Fig. 9. Patients having a complete cardiac ultrasound examin-
ation in a six-month period.
28 Journal of the Royal College of Physicians of London Vol. 20 No. 1 January 1986
Table 2. Comparison of cardiac catheterisation and angio-
graphy with PDE and 2-D echocardiography in the diagnosis of
simple congenital heart malformations (43 patients).
Patients with
positive Catheter positive diagnosis
catheter Confident positive Confident positive
diagnoses PDE diagnosis 2-D diagnosis
VSD1
PDA
Coarctation
Aortic
stenosis
Subaortic
stenosis
Pulmonary
stenosis
11
7
4
2
2
6
102
64
36
2
2
28
53
25
4
2
07
49
'Anatomy of interventricular septal otherwise normal.
2Two separately identified VSDs in one case. Muscular VSD missed in one post-
op case of Fallot's tetralogy due to non-examination of septum (see discussion).
'Suspected in a further 3 by the presence of irregularity of the membranous
septum.
4One PDA missed by PDE was angiographically tiny and not detected by
saturations.
5Suspected but not certain in a further.3 cases.
6PDE examination omitted from coarctation region in 1 case.
'Subaortic stenosis suspected from 2-D images in both cases but not certain. Aortic
valve seen to be normal in both cases.
'Three cases of pulmonary stenosis also had VSD. Turbulence in pulmonary
artery in systole could have been due to VSD so confident diagnosis not possible.
'Detail of pulmonary valve not well seen in 2 cases.
the great arteries. In none of these cases did the pulsed
Doppler echocardiography technique suggest a more
severe lesion than was actually present.
(b) In two cases of pulmonary atresia, one with a small
patent ductus arteriosus and the other with aorto-pul-
monary collaterals, there was low-intensity continuous
flow in the hypoplastic main pulmonary artery.
(c) In four out of nine atrial septal defects (ASDs), left to
right flow was detectable across the septal defect. The low
velocity of this flow made it hard to reliably diagnose
ASDs by using PDE. All the ASDs were detected on 2-D
imaging.
(d) In the one case of Fallot's tetralogy, right to left
shunting across the VSD was detected.
(e) In the case of congenital mitral regurgitation the
lesion was easily detected using PDE.
(f) In a patient with isolated pulmonary hypertension and
right heart failure PDE clearly showed tricuspid and
pulmonary regurgitation.
(g) In one case there was an aneurysm of the membra-
nous septum clearly evident on the 2-D images. This was
not associated with any turbulent flow on the PDE
examination, and angiography confirmed that the septum
was intact.
(h) In eight cases with complex disease and large VSDs of
various types, the anatomy of connections and malforma-
tions was determined by using 2-D images. The VSDs
were all clearly visualised. Useful PDE signals were hard
to obtain from the ventricular cavities in these patients,
because of the relatively low-velocity flow across the
defects.
Correlation of Clinical and Pulsed Doppler Findings in
Adults (251 patients)
All adult cases, including catheterisation patients, are
reviewed in this group.
Aortic and Mitral Regurgitation. Our results in the cathe-
terisation group of adults (see Table 1) show some
discrepancy between PDE and angiogram in the diag-
nosis of mild valvar regurgitation (especially mitral). The
results in moderate or severe regurgitation are, however,
extremely accurate and furthermore are clinically most
relevant. The clinical findings in cases with moderate or
severe regurgitation (detected by PDE) are shown in
Table 3.
Table 3. Comparison of clinical findings with pulsed Doppler
echocardiography in the diagnosis of important mitral and
aortic regurgitation. (The figures in brackets are cardiological
referrals.)
At least moderate Clinically diagnosed
No. lesion by PDE, important lesion,
of clinically PDE
cases negative negative
Aortic 251 20 1
regurgitation (157) (14) (0)
Mitral 251 9 3
regurgitation (157) (6) (1)
Twenty-nine cases of important valvar regurgitation
diagnosed by PDE were undetected clinically. In only five
of these cases was the missed lesion an isolated abnor-
mality, the remaining cases all having at least one other
valve lesion.
In a further four cases clinically suspected important
valvar regurgitation was not confirmed by PDE. Al-
though the lesions may have been missed by PDE, it is
considered probable that these four lesions were incor-
rectly assessed clinically.
Thus in 251 patients there were 33 valve lesions that
may well have been assessed incorrectly at clinical exam-
ination.
Tricuspid Valve Disease. In three cases, tricuspid stenosis
was diagnosed by PDE, the diagnosis being made by 2-D
images in two cases. The clinical signs did not allow a
confident diagnosis in any of the three cases, all of whom
had mitral valve disease. Three clinically undiagnosed
cases of important tricuspid regurgitation were diagnosed
by PDE. In all these cases of tricuspid valve disease there
was associated mitral valve disease.
Prosthetic Valve Function. Thirty-four patients with pros-
thetic valves were assessed but none was catheterised in
the review period. One mitral xenograft was suspected of
stenosis by the detection of unusually high-velocity flow
through the valve, which was sustained throughout dias-
tole. In two cases, clinically severe mitral regurgitation
Journal of the Royal College of Physicians of London Vol. 20 No. 1 January 1986 29
was diagnosed by PDE and in one of these cases a flail
xenograft leaflet was identified on the 2-D study.
In six cases of clinically diagnosed prosthetic aortic
regurgitation, the diagnosis and grading were confirmed
by PDE. In one further case of a 'stuck' aortic prosthesis,
the malfunction was shown on 2-D images and the clinical
diagnosis of severe aortic regurgitation was confirmed by
PDE. In five more cases, moderate aortic prosthetic
regurgitation was shown by PDE but was not detected
clinically. In two of these a confident statement had
specifically been made that there was no aortic regurgita-
tion.
Differential Diagnosis. In seven cases differentiation be-
tween mitral regurgitation and aortic stenosis was sought.
In one case neither lesion was detected by 2-D or PDE. In
three cases PDE showed mitral regurgitation and ex-
cluded aortic stenosis and in the remaining three cases
PDE showed no mitral regurgitation and aortic stenosis
was shown by imaging and PDE techniques. In two cases
the alternative diagnoses of mitral regurgitation or ven-
tricular septal defect were raised. In one there was clear
PDE evidence of mitral regurgitation without evidence of
a septal defect. In the second a clinically undetected ASD
was shown on 2-D images and PDE revealed associated
tricuspid regurgitation.
Discussion
It is apparent that the pulsed Doppler techniques are best
integrated into the normal echocardiographic examin-
ation. In many instances the Doppler technique serves
only to confirm clinical as well as M-mode and 2-D
diagnoses, for example in mitral stenosis (although Dopp-
ler examination can be used to obtain accurate quantita-
tion). In other cases, PDE will provide diagnostic
information that is not available by other means. It may
be difficult in a case of aortic stenosis to confirm or
exclude the presence of co-existing mitral regurgitation
but PDE can do this quite specifically.
Satisfactory images cannot always be achieved with M-
mode and 2-D ultrasound, especially from the left para-
sternal window. When images are poor the recording of a
normal mitral flow signal from the apex can allow
confident exclusion of mitral stenosis. Aortic stenosis can
be similarly confirmed or excluded from the suprasternal
position. In our own series, all cases of mitral or aortic
stenosis diagnosed by catheter were also shown by PDE.
In the remaining patients 2-D and PDE recordings
showed full agreement in the diagnosis of these lesions.
The PDE technique has proved very useful in the
detection and approximate grading of valvar regurgita-
tion. PDE is particularly sensitive in the diagnosis of
aortic regurgitation, published results showing a diagnos-
tic sensitivity of 94-95 per cent and a specificity of 82-100
per cent[14,15]. In our own small group the results are
similar, with a sensitivity of 88 per cent and a specificity
of 100 per cent. This cannot be matched by any other
diagnostic technique apart from angiography which is
currently the most accurate technique available for the
diagnosis of regurgitant valves. This level of diagnostic
accuracy has been shown in our own and other work[16]
to be superior to clinical examination. The detection of
aortic regurgitation by fluttering of the mitral valve on
M-mode studies cannot attain this accuracy[17].
PDE is also very accurate in the diagnosis of mitral
regurgitation, with a sensitivity of 91-94 per cent and a
specificity of 89-94 per cent[10,14]. Our own results in
this group are lower, sensitivity being 80 per cent and
specificity being 70 per cent. On further analysis, how-
ever, the results in all but one of the false negatives have
been due to estimates of mild mitral regurgitation either
clinically or by PDE. If haemodynamically important
lesions only were calculated (i.e. moderate or severe) then
our results would show a sensitivity of 95 per cent and a
specificity of 100 per cent. The scanning technique can be
more difficult for mitral regurgitation, and our own
experience suggests that as familiarity with the technique
increases, the diagnostic accuracy will improve. Mitral
regurgitation, especially of mild degree, is well known to
fluctuate from day to day with varying clinical circum-
stances. We have also found PDE to be useful after
catheterisation in assessing possible catheter-induced mi-
tral regurgitation.
The evaluation of right-sided lesions has proved inter-
esting. Tricuspid regurgitation may be clinically undecta-
ble except in severe cases but is easily diagnosed by PDE.
This is important because tricuspid regurgitation is a
frequent accompaniment of mitral valve disease and left
ventricular impairment.
Our results show that PDE is particularly valuable in
patients with multiple valvular lesions. PDE is no more or
less accurate for each specific lesion in these cases but
accurate clinical diagnosis becomes increasingly hard as
the number of lesions rises. In our series the majority of
'missed' lesions were in patients with more than one
valvular abnormality.
Prosthetic valve evaluation is becoming increasingly
important and PDE is a great aid in these patients for
whom further invasive investigation may be more hazard-
ous than usual. The mild stenotic pattern of prosthetic
valves must be recognised. The echogenic material of
prostheses can make scanning more difficult, but careful
technique will usually show mitral or aortic regurgitation.
It is now also possible to distinguish between paravalvar
and valvar leaks[14].
The study of acute and severe haemodynamic upset
such as rupture of the ventricular septum or papillary
muscle after myocardial infarct, infective endocarditis or
the acute derangement of a prosthetic valve is well suited
to PDE[18], In such cases the correct clinical diagnosis is
often suspected, but echocardiography with 2-D imaging
and PDE can provide rapid confirmation and allow
surgical intervention in some cases without subjecting
critically ill patients to invasive investigation.
Doppler studies are a logical extension of paediatric
echocardiography. The anatomical accuracy of diagnosis
is now well recognised but Doppler studies complement
the 2-D images in the conditions where imaging resolu-
tion is not totally accurate. Small ventricular septal
defects, patent ductus arteriosus and coarctation can be
hard to visualise or exclude by 2-D studies[19] but it is
30 Journal of the Royal College of Physicians of London Vol. 20 No. 1 January 1986
just such lesions with their high velocity turbulent jets
that are well suited to diagnosis by PDE.
The complementary nature of imaging and PDE exam-
ination is well suited to the diagnosis of some difficult
lesions. In their description of the diagnosis of coronary
artery fistulae, Miyatake et al. [20] emphasised the com-
plementary roles of 2-D and Doppler techniques. Uncer-
tain anatomical structures can often be more clearly
evaluated if flow signals from them are obtained. In our
series a case of membranous ventricular septal aneurysm
without interventricular communication could not have
been diagnosed with certainty on 2-D studies alone.
It is notable that the errors made in our series have
usually been as a result of inappropriate scanning tech-
nique rather than failure to interpret the Doppler find-
ings. It is for this reason that we feel even more accurate
results will be possible as experience in PDE grows.
Quantitative Doppler evaluation of valvar gradients,
intracardiac pressures and volume flows (cardiac output
and shunt evaluation) are all exciting prospects that are
now being evaluated. They are soon likely to join qualita-
tive Doppler echocardiography in the routine non-inva-
sive assessment of cardiac patients.
A cknowledgements
We are indebted to Miss J. Hugh and Miss N. Eberle for
typing the manuscript. We are also grateful to our
consultant cardiological colleagues in the Bristol Royal
Infirmary for allowing us access to their patients' clinical
records.
V '
f
I
References
1. Wells, P. N. T. (1969) Medical and Biological Engineering, 7, 641.
2. Griffiths, J. M. and Henry, W. L. (1978) Circulation, 57, 925.
3. Goldberg, S.J. and Sahn, D.J. (1982) American Journal of Cardiolo-
gy, 50, 1394.
4. Richards, K. L., Cannon, S. R., Crawford, M. H. and Sorensen,
S. G. (1983) American Journal of Cardiology, 51, 1122.
5. Veyrat, C., Kalmanson, D., Farjon, M., Manin, J. P. and
Abitbol, G. (1982) British Heart Journal, 47, 596.
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Journal, 43, 284.
7. Thuillez, C., Theroux, P., Bourassa, M. G. etal. (1980) Circulation,
61, 381.
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G. (1978) Circulation, 58, 322.
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Adolescent Echocardiography. (2nd ed) Chicago: Year Book Medical
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Journal of the Royal College of Physicians of London Vol. 20 No. 1 January 1986 31
|
PMC005xxxxxx/PMC5371134.txt | Diabetes Mellitus and Hypertension in an
African Population
p
J. M. OLI, MB, MRCP(UK), FRCPEd*
Reader and Consultant Physician
r?
V. O. IKEH, MD
Lecturer and Consultant Cardiologist
Department of Medicine, University of Nigeria Teaching Hospital, Enugu, Nigeria
The cardiovascular complications of diabetes mellitus are
now well recognised and probably account for most of the
accelerated death rates in diabetics. The adverse effect of
hypertension on the progression of the cardiovascular
complications such as coronary heart disease (CHD),
cerebrovascular disease (CVD), and peripheral vascular
disease (PVD) in diabetics has been well documented by
the Framingham study[l,2]. The prevalence of hyperten-
sion in diabetic populations has been controversial for
many years. Of more recent reports, Pell and
D'Alonzo[3] found a greater prevalence of hypertension
(> 150/94 mm Hg) in diabetics than non-diabetics, while
in the Framingham study mean systolic pressures were
slightly higher in diabetics and more so in female patients
[4]. Jarrett et al. [5] showed a correlation in men aged over
40 years of both systolic and diastolic pressures with blood
glucose, and Barrett-Connor et al.[6] showed an associ-
ation between diabetes and hypertension in both sexes
and at all ages. On the other hand, Freedman et al.[7]
found no significant difference in the prevalence of
hypertension in diabetics and non-diabetics of both sexes,
except in the 70-79 year age group where the rate was
considerably higher in diabetics. Additional evidence
favouring an association between diabetes and hyperten-
sion comes from Ostrander et al. [8] who found the
prevalence rate of hyperglycaemia to be significantly
increased in both male and female hypertensives.
The studies cited were mostly carried out in Caucasoid
populations; studies on this topic in the developing
countries of Africa are scarce[9] and the conclusions must
be limited since the criteria for the diagnosis of hyperten-
sion may not have taken age, sex and weight into
account, and the non-diabetic control populations may
have been unsatisfactory. This article records our investi-
gation of the prevalence of hypertension in Nigerian
diabetics and two non-diabetic control groups.
Patients and Methods
The diabetics were the 402 (195 males and 207 females)
patients regularly attending the diabetic clinic of the
University of Nigeria Teaching Hospital (UNTH) at
Enugu, Nigeria. Diagnosis of diabetes had been made by
blood glucose estimations (fasting blood glucose >8.0
mmol/litre or random or 2-hour post-prandial blood
glucose >11.0 mmol/litre). At the diabetic clinic, per-
iodic examinations including blood pressure and body
weight (at each clinic visit), are usually carried out.
Routine tests include urinalysis at each clinic visit to
detect the presence of sugar and albumin. Diabetics who
were known hypertensives before developing diabetes
were excluded from this study.
We have used two control groups in this study (a) non-
diabetic subjects attending the medical out-patient clinics
of the UNTH?out-patient population (OPP); (b) non-
diabetic subjects in the general population (GP) drawn
mainly from factory and hospital workers. Diabetes melli-
tus was excluded in the controls by the absence of sugar in
the urine and/or blood glucose estimations.
Weight Measurements
Although the main interest in this study is the relationship
of hypertension to diabetes, we have included analysis of
body weights since there is a strong association of over-
weight with both hypertension and diabetes[10]. The
subjects were considered to be overweight if the weight
was 20 per cent above the mean weight for age and sex,
using figures published by the Metropolitan Life Insur-
ance Companyfll], To our knowledge no such figures
are available for Africans. Those overweight were further
divided into moderately overweight (weight 20-30 per
cent above the mean for age and sex) and very overweight
(weight more than 30 per cent above the mean). Thus all
subjects were finally grouped into (a) not overweight; (b)
moderately overweight, and (c) very overweight.
Matching of Diabetic Subjects with Controls
For each diabetic, a control was selected from each
control group to match the diabetic for age, sex and
weight grouping. The age matching was done by selecting
a control who was not more than two years younger or
"Correspondence to Dr J. M. Oli
32 Journal of the Royal College of Physicians of London Vol. 20 No. 1 January 1986
Table 1. Prevalence of hypertension among the diabetics and controls. D?diabetics; OPP?out-patient population; GP?general
population; NS?not significant.
Hypertensives
No. (%) P value against D
Age (yr) Total no. D OPP GP OPP GP
<30 18 0(0) 1(5.5) 1(5.5) ? ?
31-40 48 15(31.3) 8(16.7) 8(16.7) NS NS
41-50 99 21(21.2) 25(25.3) 18(18.2) NS NS
51-60 141 75(53.2) 46(32.7) 32(22.7) ^<0.0005 P<0.005
>60 96 36(37.5) 28(29.2) 18(18.8) NS /><0.005
Total 402 147(36.6) 108(26.9) 77(19.2) P<0.005 P< 0.005
older than the diabetic. All subjects, diabetic and non-
diabetic, were non-smoking, urbanised Nigerians.
Blood Pressure Measurements
Blood pressure (BP) measurements were made with the
subject either sitting or lying down. In those with 160 mm
Hg systolic and/or 95 mm Hg diastolic or above these
figures, the measurements were repeated on at least two
subsequent occasions. A diagnosis of hypertension was
made if the blood pressure remained at or above these
figures on these occasions in patients not on anti-hyper-
tensive therapy. The diastolic end point was taken as the
phase 4 muffle. The diabetics and OPP subjects who were
known hypertensives on medication were included as
hypertensives in this study only if their BP prior to anti-
hypertensive therapy had been noted to be at the level
quoted above. All the GP subjects who were known
hypertensives on medication, and in whom the pre-
treatment pressures could not be ascertained, were in-
cluded in this study as hypertensives.
Statistical Analysis
This was done between diabetics and controls using the x2
with Yates' correction.
Results
The subjects consisted of 402 diabetics, 402 OPP control
subjects and 402 GP control subjects (195 males and 207
females aged 12-78 years; mean 50.0 years in each
group). Table 1 shows the prevalence of hypertension
among the diabetics and control subjects. Of the diabetics
147 (36.6 per cent) were hypertensive compared to 108
OPP control subjects (26.9 per cent) and 77 GP control
subjects (19.2 per cent). The difference between the total
number of diabetics and the total number of OPP control
subjects who were hypertensive is statistically significant
(P < 0.005). The difference between the total number of
diabetics and the total number of GP control subjects who
were hypertensive is even more significant (P< 0.0005).
The age grouping shows that the preponderence of
hypertensive diabetics over the control subjects is evident
only in the groups over 50 years old, except in the over 60
group in the OPP control subjects. Table 2 shows the
Table 2. Prevalence of hypertension among diabetics and
controls by age (under 50 and over 50 years) and sex. D?
diabetics; OPP?out-patient population; GP?general popu-
lation; NS?not significant.
Hypertensives
No. (%) P value against D
Age (yr) Total
and sex No. D
OPP GP
OPP
GP
Males
<50 81
>50 114
Total 195
15 18 10 NS NS
60 44 30 P< 0.05 P< 0.0005
75 62 40 NS P< 0.0005
Females
<50 84
>50 123
Total 207
21 16 17 NS NS
51 30 20 /*< 0.005 P< 0.0005
72 46 37 P< 0.005 P< 0.0005
prevalence of hypertension among diabetics and controls
by age (under 50 and over 50 years) and sex. It also shows
that in those over 50 years old, the prevalence of hyper-
tension among the diabetics is more evident in the females
that the males when compared with each control group.
In fact there is no significant difference between the total
number of male diabetics and the total number of OPP
control subjects.
Table 3. Prevalence of hypertension among the diabetics in
relation to duration of diabetes.
Duration of No. of No. of
diabetes (yr) diabetics hypertensives %
1-4 165 48 29.1
5-9 162 66 40.7
10+ 75 33 44.0
Total 402 147 36.6
Tables 3 and 4 show that the prevalence of hyperten-
sion among the diabetics increased with duration of
diabetes and that the increased prevalence of hyperten-
sion among the diabetics compared to the controls was
not related to the presence of albuminuria (and presum-
Journal of the Royal College of Physicians of London Vol. 20 No.l January 1986
Table 4. Prevalence of hypertension related to presence of
albuminuria in the diabetics and controls. D?diabetics; OPP?
out-patient population; GP?general population.
Group No. with Albuminuria No. with Hypertension %
D 78 38 48.7
OPP 50 27 54.0
GP 20 12 60.0
ably kidney disease). In fact the percentage of subjects
with albuminuria who had hypertension was higher in the
control groups.
Thirty of the diabetics had the insulin-dependent, type
I diabetes (IDDM); 3 of them (10 per cent) were hyper-
tensive compared to 3 OPP and 2 GP controls. The rest
(372) had non-insulin dependent type II diabetes
(NIDDM); 144 (38.7 per cent) were hypertensive.
Discussion
This study shows that hypertension is more common in
Nigerian diabetics than in both the general population
and out-patient population in both sexes but only after
the age of 50 years, the prevalence increasing with
duration of diabetes. This is more so in the females than
the males and when the general population rather than
the out-patient population is used as controls. The abnor-
mally high prevalence of hypertension among control
groups drawn from a hospital population rather than the
general population should therefore be taken into account
when selecting controls in epidemiological studies of
hypertension.
Our findings agree with recent conclusions that in
Caucasians the increased prevalence of hypertension in
diabetics is mainly in those over 50 years of age and that
any increased prevalence of hypertension, at least before
old age, is not wholly convincing[12]. By matching the
diabetics with the controls for degrees of overweight, our
study highlights the fact that the increased prevalence of
hypertension among diabetics is independent of weight.
Furthermore (Table 3), the increased prevalence of hy-
pertension among the diabetics is independent of the
renal complications of diabetes. These facts are also true
of Caucasians[3,6]. All the subjects in the study were
non-smoking, urbanised Nigerians, thus the effect of
smoking and urbanisation on the prevalence of hyperten-
sion could not bias the results. Barrett-Connor et al.[6]
found a tendency towards higher blood pressure in
persons with fasting hyperglycaemia but no history of
diabetes. This suggests that the association between
diabetes and hypertension is not entirely a function of
ascertainment (Berksonian bias).
The bulk of diabetics in this study is, as expected, of
type II, and no meaningful conclusion can be drawn
about the prevalence of hypertension in type I diabetes
since the number of type I diabetics is small in this study,
as in Africans in general[13]. However, Christlieb et al.
[14] found a significant excess of hypertension among
juvenile-onset insulin-dependent diabetics. Definite
hypertension in this group is usually associated with renal
involvement.
Some known hypertensives on treatment among the
general population in this study may not have satisfied
the criteria used in the diagnosis of hypertension, as their
pre-treatment BP levels were unknown. However, this
should not influence our conclusions since their inclusion
could only have led to an over-estimation in the preva-
lence of hypertension in this control group. Some pre-
vious studies of the association between diabetes and
hypertension ignored the possible role of anti-hyperten-
siv.e therapy, such as diuretics, in the genesis of diabetes.
By only including diabetics who developed hypertension
during the course of diabetes we avoided this possible
effect.
Arterial hypertension is a common cardiovascular dis-
ease in Africans and carries high mortality and morbidity
rates. Various epidemiological studies have shown that
the frequency of this disease ranges from 23-27 per cent
in some urban African populations[15-18]. This com-
pares with the prevalence of 26.9 per cent and 19.2 per
cent found respectively in the OPP and GP control
subjects in our study. The prevalence of 36.6 per cent for
hypertension in our diabetic population compares with
the 40 per cent reported recently in Nigerians[19]. Like A
Greenwood and Taylor [20] we also found hypertension
to be more common in elderly female diabetics. , 4
Various reports have suggested an association between
hypertension and the development of some diabetic com-
plications such as diabetic retinopathy[21-23], diabetic
nephropathy[24], CHD[25], CVD[26], and PVD[27],
although it is not clear if control of hypertension prevents
the development or progression of some of these compli-
cations. However, two of the diabetic complications,
namely CHD[28] and PVD[9] seem uncommon in Afri-
cans, yet hypertension, which is a risk factor for both
conditions in Caucasians, is common in African diabe-
tics. It has been suggested that the low prevalence of
CHD in black populations, including diabetics, may be
due to the occurrence of relatively high levels of HDL ,
cholesterol[29-31]. Thus high total cholesterol levels
might be benign if associated with higher levels of HDL
cholesterol. It will be of interest to know if hypertension
plays any major role in the development of these two
complications in the few African diabetics who develop ,
the complications. Indeed, a clinical report from the
University Hospital in Ibadan, Nigeria (1961-1970) in-
cluded 26 patients with myocardial infarction, five of
whom had diabetes and hypertension[32].
Nearly all anti-hypertensive drugs have some signifi-
cant disadvantages when used in diabetic subjects
[33,34], Choice of any drug will clearly depend on the
type of diabetes, adverse effects of the drugs concerned,
presence of complications and the presumed pathophysio-
logy of the hypertension. In general, thiazide diuretics '
and beta-blockers, despite their limitations, remain the
initial drugs, used in combination where one is inad-
equate[35]. However, this may be confounded by the
suggestion that some black patients (Jamaican blacks and
South African Zulus) with hypertension do not respond to
beta-blockers unless diuretics are added[36,37]. Beta-
34 Journal of the Royal College of Physicians of London Vol. 20 No. 1 January 1986
blockers may only act in these patients once the excess
plasma volume or sodium concentration is corrected by
diuretics[36]. Evidence similarly suggests that some
blacks with hypertension have low plasma renin activity
[38], Diuretics such as chlorthalidone increase plasma
renin activity but some studies indicate that beta-blockers
are effective even when used alone in Nigerian patients
with moderate hypertension[39,40], suggesting that there
may be differences in the extent of excess plasma volume,
sodium concentration and plasma renin activity between
different groups of blacks.
The mechanisms for the increased prevalence of hyper-
tension in diabetics remain unclear. These have included
the possible role of endogenous opiates, abnormalities of
central catecholamine control, increase in exchangeable
sodium due to hyperinsulinism seen in obese type II
diabetes, a defect in the renin-angiotensin system, raised
blood viscosity and arterial stiffness and increased platelet
aggregation[12]. Of particular interest with regard to
Africans is the finding that Nigerian diabetics have
decreased erythrocyte deformability and increased fibrin-
ogen levels, particularly in those with hypertension[41].
Tibblin et al.[42] first observed an increased blood vis-
cosity in patients with essential hypertension that was
directly related to an increased haematocrit and fibrino-
gen. This could perhaps provide an attractive hypothesis
concerning the pathogenetic mechanism of hypertension
in diabetes, since an increased blood viscosity can only be
compensated for by an increased perfusion pressure or by
vasodilation. Additionally, Nigerian diabetics with hae-
moglobin genotype AS have a greater degree of increased
erythrocyte deformability and fibrinogen levels (Reid,
personal communication) and higher prevalence of hy-
pertension than Nigerian diabetics with haemoglobin
genotype AA. This suggests that Nigerian diabetics with
haemoglobin genotype AS may have a greater risk of
developing hypertension and/or renal complications than
those with genotype AA[43].
This study shows that hypertension is more common in
Nigerian diabetics than in non-diabetic populations after
the age of 50 years. Evaluations of the consequences of
cultural change suggest that with increasing urbanisation
of African populations and consequent changes in life
style due to socio-economic changes, the prevalence of
both diabetes and hypertension will increase[44-46]. The
association between the two diseases will become stron-
ger, with a resultant increase in cardiovascular mortality
and morbidity. While adequate detection and treatment
of hypertension may provide preventive care for African
diabetic populations, a better alternative may be preven-
tion of the emergence and entrenchment of social, econ-
omic and cultural patterns of living known to elevate risk
factors in the prevalence of hypertension and diabetes in
developed countries.
References
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(1970) Journal of the American Medical Association, 214, 301.
2. Kannel, W. B., Gordon, T. and Schwartz, M.J. (1971) American
Journal of Cardiology, 27, 335.
3. Pell, S. and D'Alonzo, C. A. (1967) Journal of the American Medical
Association, 202, 104.
4. Dawber, T. R. (1980) In The Framingham Study, p.190. Cambridge,
Mass: Harvard University Press.
5. Jarrett, R. J., Keen, H., McCartney, M. et al. (1978) International
Journal of Epidemiology, 7, 15.
6. Barrett-Connor, E., Criqui, M. H., Klauber, M. R. and Hold-
brook, M. (1981) American Journal of Epidemiology, 113, 276.
7. Freedman, P., Moulton, R. and Spencer, A. G. (1958) Quarterly
Journal of Medicine, 27, 293.
8. Ostrander, L. D. Jr, Francis, T. Jnr, Hayner, N. S., Kjelsberg,
M. D. and Epstein, F. H. (1965) Annals of Internal Medicine, 62,
1188.
9. Tulloch, J. A. (1962) In Diabetes mellitus in the tropics, pp. 128-30.
Edinburgh and London: E. & H. Livingstone.
10. Heyden, S. (1978) Nutrition and Metabolism, 22, 141.
11. Metropolitan Life Insurance Co. (1959) Statistical Bulletin, 40, 1.
12. Drury, P. L. (1983) Diabetologia, 24, 1.
13. Oli, J. M. (1983) Journal of the Royal College of Physicians of London, 4,
224.
14. Christlieb, A. R., Warram, J. H., Krolewski, A. S. et al. (1981)
Diabetes, 30, suppl. 2, 90.
15. Parry, E. H. O., and Ikeme, A. C. (1966) Cardiovascular disease in
Nigeria. Ibadan: University Press.
16. Akinkugbe, O. O. (1972) High blood pressure in the African. London:
Churchill.
17. Falase, A. O. (1978) Tropical Cardiology, 45, 59.
18. Seedat, Y. K. and Seedat, M. A. (1982) Transactions of the Royal
Society of Tropical Medicine & Hygiene, 76, 624.
19. Oviasu, V. O. and Abu-Bakara, A. (1983) Tropical Cardiology, 9,
115.
20. Greenwood, B. M. and Taylor, J. R. (1968) Tropical and Geographi-
cal Medicine, 20, 1.
21. Kornerup, T. (1957) Acta Ophthalmologica (Copenhagen), 35: 163.
22. Keen, H. (1972) Journal of the Royal College of Physicians of London, 7,
53.
23. Knowler, W. C., Bennett, P. H. and Ballintine, E. J. (1980) New
England Journal of Medicine, 302, 645.
24. Christiansen, J. S., Gammelgaard, J., Frandsen, M. and Parving,
H. H. (1981) Diabetologia, 20, 457.
25. Kannel, W. B. and McGee, D. L. (1979) Circulation, 59, 8.
26. Asplund, K., Hagg, E., Helmers, C., Lithner, F., Strand, T. and
Westor, P. O. (1980) Acta Medica Scandinavica, 207, 417.
27. Janka, H. V., Standi, E. and Mehnert, H. (1980) Diabetes Care, 3,
207.
28. Watkins, L. O. (1984) American Heart Journal, 108, 850.
29. Miller, G. J. and Miller, N. E. (1975) Lancet, 1, 16.
30. Walker, A. R. P. and Walker, B. F. (1978) British Medical Journal,
2, 1336.
31. Aduba, O., Onwuameze, I., Oli, J. and Udeozo, K. (1984) East
African Medical Journal, 61, 35.
32. Falase, A. O., Cole, T. O. and Osuntokun, B. O. (1973) Tropical
and Geographical Medicine, 25, 145.
33. Husserl, F. E. and Messerli, F. H. (1981) Drugs, 22, 188.
34. Waal-Manning, H.J. (1979) Drugs, 17, 157.
35. Christlieb, A. R. (1980) Cardiovascular Review, 1, 609.
36. Seedat, Y. K. (1980) British Medical Journal, 281, 1241.
37. Humphreys, G. S. and Delvin, D. G. (1968) British Medical Journal,
11, 601.
38. Wisenbangh, P. E., Garst, J. B., Hull, C., Freedman, R. J.,
Mathews, D. N. and Hadady, M. (1972) American Journal of
Medicine, 52, 175.
39. Oli, J. M. (1981) Current Therapeutic Research, 30, 477.
40. Oli, J. M. (1982) Current Therapeutic Research, 31, 93.
41. Reid, H. L., Obi, G. O. and Oli, J. M. (1984) Acta Diabetologia
Latina, 21, 105.
42. Tibblin, G., Bergentz, S. E., Bjure, J. and Wilhelmsen, L. (1966)
American Heart Journal, 72, 165.
43. Oli, J. M. (1985) Tropical and Geographical Medicine, in press.
44. Jackson, W. P. U. (1970) Acta Diabetologia Latina, 7, 361.
45. Oviasu, V. O. and Okupa, F. E. (1980) Bulletin of the World Health
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African Medical Journal, 61, 999.
Journal of the Royal College of Physicians of London Vol. 20 No. 1 January 1986
|
PMC005xxxxxx/PMC5371135.txt | Book Review
The Value of Preventive Medicine,
edited by D. Evered and
Julie Whelan. Ciba Foundation Symposium 110. Pitman
Medical, London, 1985. 258 pages. Price ?27.95.
This is a rather unusual topic for a Ciba Foundation
Symposium dealing not, as in most of the series, with the
details of a fairly circumscribed subject but with the many
broad considerations, social and economic as well as
medical, that need to be considered in prevention. Con-
tributors and participants came from the UK, USA,
Belgium, Switzerland, Bulgaria, Sweden, Norway, Aus-
tralia, Japan and Canada. The objectives of preventive
medicine are considered by Sir Richard Doll. It may not
be very long before the great majority of deaths will occur
at 80 to 85 years of age but a general increase in longevity
beyond 90 or 100 years seems unlikely. Improvements
that are possible depend on a substantial reduction in
mortality from three groups of diseases that are now the
main causes of death under the age of 85?neoplasms,
ischaemic heart disease and other vascular disease.
Whether a reduction in age-specific mortality will also
result in less disability is unclear. David Weatherall
considers the impact of new methods of gene analysis on
screening for genetic disease. Beneficial results that would
follow from the control of tobacco-related disease are
dealt with by Richard Peto. The controversial issue of the
preventability or otherwise of coronary heart disease is
discussed at length. Between them, several contributors
review the major primary prevention trials in some detail.
Much of the discussion in the chapters concerned deals
with the difficulties of designing and interpreting such
trials and, being a good deal less formal than the way in
which these points are usually handled, it is of special
value. Is the randomised controlled trial the pinnacle of
scientific evidence? Do preventive trials test aetiological
hypotheses or evaluate policies?or both? These are some
of the questions raised by Geoffrey Rose. Screening for
cancer, screening and intervention in alcohol-related
disease and the value of physical fitness are further
medical or physiological topics included.
Other contributors outline the economic aspects that
have to be borne in mind. Particularly useful in what can
very easily become a confusing subject is the chapter by
Jeffrey Koplan on the benefits, risk and costs of immunis-
ation programmes. This reviews studies on a number of
particular vaccines such as those against poliomyelitis,
Continued on page 66
62 Journal of the Royal College of Physicians of London Vol. 20 No. 1 January 1986
Continued from page 62
pertussis, measles and influenza and it is not hard to see
that they mostly result in a net saving to society?as well
as achieving an important medical objective. However,
Koplan emphasises that the value of cost-benefit and cost-
effectiveness analyses often lies not only in providing a
'definitive basis for a decision' but also in providing a
framework which enables decision-makers to consider all
the issues. An interesting and always topical example
concerns pertussis immunisation. In a model that reflects
herd immunity, the benefit-cost ratio is more than 11 to
1. When no herd immunity is assumed, the ratio is more
like 3 to 1. Moving from the relatively clear-cut picture in
infectious disease, a recurring point in considering non-
communicable disease was that prevention certainly isn't
cheap. On coronary disease, the work of Berwick and his
colleagues on the cost-effectiveness of four options for
prevention starting in childhood was considered as a
general example of the elements that have to be taken into
account in analyses of this kind. The options were to do
nothing, to screen all children and treat those with high
cholesterol levels, to screen a limited number of high-risk
children and treat those with high levels and, finally, to
attempt to lower lipid levels through population-wide
educational intervention without any screening. The
main measure was the cost per year of life saved. The best
buy would have been the fourth option?mass media
education.
I have to declare an interest (which the Editor felt was
acceptable) in that I was one of the contributors to the
symposium. That said, this is certainly a book worth
consulting to find out more about the realities underlying
the general (and obviously reasonable) belief that, where
it's possible, 'prevention is better than cure'.
66 Journal of the Royal College of Physicians of London Vol. 20 No. 1 January 1986
|
PMC005xxxxxx/PMC5371136.txt | Inflammatory Bowel Disease and Food
Intolerance
H. J. F. HODGSON, DM, FRCiR Senior Lecturer and Consultant Physician, Department of
Medicine, Royal Postgraduate Medical School, Hammersmith Hospital, London
Are the idiopathic inflammatory bowel diseases, ulcer-
ative colitis and Crohn's disease, manifestations of food
allergy? This question is often posed by patients, and
increasingly by doctors. We do not know enough to give a
short answer, so this article attempts to give a long one.
j
i - The Gut and Food Allergy
Various forms of food intolerance exist, and a distinction
is usually drawn between adverse reactions that are
allergic or immunological in origin, and those that are
idiosyncratic, in which symptoms may be pharmacologi-
cal in origin, or metabolic, reflecting, for example, a
genetically determined enzyme defectfl]. Both allergy
and idiosyncracy need to be considered in the context of
inflammatory bowel disease, but the concept of allergy
underlying the conditions has received most attention.
Indeed, the gut would seem to be a highly likely site for
the manifestation of food allergy. The antigens in food are
present in high concentration at the surface of the gut
mucosa, which is permeable to allow the gut to fulfil its
absorbtive function, and within which there is a highly
organised local immune system, encompassing both hu-
moral and cell-mediated immunity. It might indeed be
thought surprising that food-allergic manifestations, aris-
ing either within the gut or the rest of the body, are not
universally present in the population. That this is not so
reflects some of the specialised aspects of the gut immune
system. There are two major features of importance.
The first is the local production within the gut mucosa
of the specialised mucosal immunoglobulin, IgA. Secre-
tory IgA, directed in part against antigens present in
food, lines the mucosa of the intestine and helps prevent
penetration of antigen into the gut mucosa. The combi-
nation of secretory IgA with its antigen appears to be an
undramatic process, as the resulting antigen-antibody
complex lacks the ability to fix complement readily, and
therefore does not induce local inflammation[2].
The other major feature is that, experimentally, devel-
opment of a local IgA immune response in the gut mucosa
against specific antigen can often be shown to be linked
with induction of systemic tolerance, i.e. specific non-
responsiveness of the systemic immune system of the
body to subsequent challenge with that antigen[3], Teleo-
logically this process would seem desirable in preventing
major systemic allergic responses to food.
An abnormal gastrointestinal immune response to food
might therefore lead in different ways to allergic manifes-
tations. An inadequate local gastrointestinal immune
response, without induction of systemic tolerance to food
antigens, might underlie systemic forms of allergy. In
contrast, an enhanced local immune response, in which
mechanisms other than IgA production are recruited,
might lead to local gut inflammation. Some form of this
latter process is often cited in attempts to explain the
chronic inflammatory bowel diseases.
Allergic Manifestations in the Gastrointestinal Tract
Acute gastrointestinal allergic disease is relatively com-
mon, usually recognised by patients themselves, and
rarely a clinical problem. Oral oedema, abdominal pain
and diarrhoea, sometimes associated with systemic mani-
festations such as asthma, may reflect an acute IgE-
mediated response to specific food antigens, readily
confirmed if necessary by prick testing or detection of
specific IgE in the serum. The acuteness of this form of
allergy makes it a poor model for ulcerative colitis and
Crohn's disease, chronic conditions which often show
continuous disease activity over many months or even
years. There are, however, good examples of diseases that
seem to be immunologically mediated which are charac-
terised by chronic inflammation in the gut. These include
coeliac disease (although an immunological basis is not
universally accepted) and, most intriguingly for the pur-
poses of this article, the milk allergic colitis recognised in
infants. For example, studies at the Hospital for Sick
Children, London, demonstrated a bimodal age of pres-
entation of clinical 'colitis' with rectal bleeding and
diarrhoea[4]. While older children followed the course of
classical ulcerative colitis, those presenting at an early age
had a colonic inflammatory infiltrate with a prominent
eosinophilic component. These infants often had evidence
of IgE-mediated reactions to cows' milk, and remitted on
withdrawing this antigen from their diet. Is this condition
a model for the chronic inflammatory bowel diseases seen
in later life?
To try and answer this question, we shall first survey
the evidence for abnormal reactions to food antigens in
patients with ulcerative colitis and Crohn's disease, and
then survey the evidence that removing or altering the
ingestion of food antigens affects the disease. Both ulcer-
ative colitis and Crohn's disease will be considered
together, for the evidence of abnormal immune responses
Journal of the Royal College of Physicians of London Vol. 20 No. 1 January 1986 45
in these diseases is virtually identical; indeed many of the
family studies indicate that these conditions are variants
of a single disease process[5].
Immune Responses to Food Antigens in Inflammatory
Bowel Disease
There is strong evidence of immunity against food anti-
gens among patients with inflammatory bowel disease. It
is not this finding but its interpretation which is uncer-
tain. The damaged intestinal mucosa in inflammatory
bowel disease has an enhanced permeability, which pre-
sumably permits more, or larger size, antigenic particles
derived from food to penetrate[6]. This mechanical
breaking of the local immune barrier seems likely to
enhance the local generation of immunity to food anti-
gens, and to permit development of systemic immune
responses. Evidence of immune responses to food might
therefore be considered as secondary phenomena of no
importance. However, an alternative interpretation is
that locally-generated immune responses against food
antigens perpetuate inflammation in the gut by, for
example, persistent antigen-antibody complex-mediated
tissue damage.
The evidence for immune response against food may
be summarised as below, following the classical Gell and
Coombs classification.
Type 1, IgE-mediated Immune Responses
Some early studies suggested that the classical atopic
disorders, which reflect a tendency to develop IgE-
mediated immune responses to common extrinsic anti-
gens to a greater degree than normal, were more common
in patients with inflammatory bowel disease. Further-
more, in some patients, particularly those with localised
proctitis, there may be a prominent eosinophilic com-
ponent to the inflammatory infiltrate, and peripheral
eosinophilia is not uncommon[7]. Some controlled thera-
peutic trials have reported beneficial responses to the local
administration of cromoglycate, which inhibits IgE-medi-
ated damage by preventing degranulation of mast
cells[8]. However, the benefits of this treatment are
minor, and have not always been confirmed. In addition
the most meticulous studies on atopy in inflammatory
bowel disease do not suggest that atopic disorders in
general are more common than in the whole popu-
lation^]. They do, however, suggest that among atopic
individuals with inflammatory bowel disease, evidence of
immediate-type skin hypersensitivity to food is more
common than among atopic individuals without gut
disease. This would suggest merely that among individ-
uals with a tendency to develop reaginic antibody, the
presence of inflammatory bowel disease, and thus en-
hanced penetration of food antigens, is more likely to
result in reaginic antibodies to food.
Type II
The search for circulating antibodies in inflammatory
bowel disease has produced findings that have contribut-
ed significantly to the immunological theories of inflam-
matory bowel disease. However, they have been mainly
concerned with antibodies to antigens other than food.
The main findings can be summarised as follows:
1. Many patients have circulating autoantibodies to co-
lonic epithelium[10].
2. Antibodies in the serum of patients with inflammatory
bowel disease can initiate antibody-dependent lympho-
cyte cytotoxicity directed against colonic epithelial cells
in vitro[ 11],
3. There are cross-reacting antigens between bacteria
commonly present in the lumen of the colon, and
colonic epithelium. This might result in immune re-
sponses initially directed against bacteria inflicting
damage on the colon[12].
Some workers have felt that these events underlie the
pathogenesis of inflammatory bowel disease. In contrast,
the detection of circulating antibody against food protein
has seemed of little relevance. For example, antibodies
against bovine proteins are readily detected in inflamma-
tory bowel disease, but they are also found in patients
with other inflammatory lesions of the gut such as coeliac
disease, and in apparently normal individuals[13].
Type 111
The histological appearance of the inflammatory infiltrate
in inflammatory bowel disease has been likened to the
Arthus reaction, representing the inflammatory conse-
quences of an antigen-antibody complex formation. This
might well reflect the combination of antibody, either
from the circulation or more likely produced locally
within the mucosa, with antigens from the gut. The
ability of antigen-antibody complexes to initiate chronic
inflammation in the gut mucosa has been reproduced
experimentally[14]. Again, however, bacterial antigens
are better established as potential contributors to this
process than food antigens, as there is evidence of local
production of anti-bacterial antibody within the colonic
mucosa[15], but theoretically food antigens could also act
in this way. An attraction of this hypothesis is that
deposition of immune complexes elsewhere in the body,
perhaps from the circulation after being formed in the
gastrointestinal mucosa, could explain those systemic
complications of inflammatory bowel disease, such as
iritis, arthritis and erythema nodosum that are strongly
reminiscent of serum sickness[16].
Type IV
In contrast to the considerable work in defining antibody
reactions to both food and bacterial proteins in inflamma-
tory bowel disease, fewer studies have been made on cell-
mediated immunity. There is little direct evidence of cell-
mediated immunity to food antigens in man. However,
experimentally cell-mediated immunity against extrinsic
antigen introduced into the gut lumen has produced a
chronic colitis[17].
Thus there is good evidence that patients are sensitised
to food proteins, but little evidence to suggest that this
46 Journal of the Royal College of Physicians of London Vol. 20 No. 1 January 1986
\
\
'?L
sensitisation plays a critical role in maintaining inflam-
mation. Suggestive evidence, however, comes from a
variety of clinical studies.
1
Clinical Studies of Food Antigen Withdrawal
The literature of the early half of this century contains
many accounts of successful treatment of ulcerative colitis
by withdrawal diet, remission being induced by with-
drawal of potatoes, chocolates, milk, tomatoes, etc. All
these observations were uncontrolled, and clearly un-
impressive in a disease characterised by frequent spon-
taneous relapses and remissions. The controlled evidence
for benefit from removal of specific allergens is very
scarce.
The most quoted trial of withdrawal of a single food-
stuff is that of Wright and Truelove, who tried the effect
of milk withdrawal in ulcerative colitis[18]. The result of
this trial is summarised as 'one patient in five had some
benefit from milk withdrawal' ? with the complex
statistical appendix reflecting significance of some tests
but not others. The details of this trial are worth empha-
sising. The main comparison was not between a milk-free
diet and a normal diet, but between a milk-free diet and
one in which patients were advised to drink milk liberally.
Subsequent work has emphasised that patients with in-
flammatory bowel disease may be intolerant of milk, not
on the basis of an allergy but of idiosyncracy[19]. Lactase
deficiency resulting in unhydrolysed lactose reaching the
colon, where it may initiate a fermentative diarrhoea, is
more common in patients with inflammatory bowel dis-
ease, and some of the symptomatic differences between a
low and a high milk diet could be explained on this basis.
But it is also possible that this study did indeed reflect a
beneficial immunological effect of removal of this particu-
lar antigen, and patients with the highest level of milk
precipitins were more likely to do better, but it was not
possible to correlate improvement with changes in circu-
lating milk precipitin levels. In a different group of
patients studied subsequently, immediate hypersensiti-
vity to milk proteins was not more common in inflamma-
tory bowel disease than in the general population[20].
There is little other controlled evidence on withdrawal
of specific items of food in inflammatory bowel disease,
but there are now a number of studies indicating that
'bowel rest', which involves removal of food and food
antigens from the lumen, may be effective in inducing
clinical remission. Most of this work pertains to Crohn's
t disease rather than ulcerative colitis, but it is not clear
whether this reflects a true biological difference, or merely
that frustration with the current treatment of Crohn's
disease has led to continuing experimentation in treat-
ment, whereas ulcerative colitis is usually readily control-
lable by current medical means.
Bowel rest has been achieved in a number of different
ways. Colonic Crohn's disease has been treated by
double-barrelled ileostomy, with diversion of the faecal
stream, resulting in decreased inflammation within the
excluded segment[21]. While removal of antigenic food
residues might explain this, profound changes in the
motility, the consistency of the intraluminal contents and
the bacterial flora of the excluded colonic segment will
also occur, and it is difficult to interpret these changes.
Some evidence suggests that reintroduction of faecal
filtrates into the excluded segments can reinitiate inflam-
mation, with a particle smaller than a bacterium being
responsible for this phenomenon, but clearly the bacterial
products are still as likely to be responsible as food
antigens[22].
Striking clinical improvement has been reported in
Crohn's disease, particularly in adolescents, from the use
of total parenteral nutrition, which rests both small and
large gut[23]. An allied approach is the use of an
elemental diet, which avoids the risks of central venous
feeding and removes food antigens by providing food in
the form of simple molecules of carbohydrate, fatty acids,
and amino acids or peptides of a molecular size so small
that they are unlikely to be antigenic. There seems little
doubt now that these approaches can induce remission in
Crohn's disease, and in a controlled trial the effects of an
elemental diet, although slow, have been similar to those
of conventional treatment with corticosteroids, with a fall
in indices of inflammation as well as clinical improve-
ment[24].
The interpretation of these findings is very difficult.
The nutritional state of patients may well be of consider-
able importance. Many patients with inflammatory bowel
disease are malnourished, and re-feeding malnourished
patients alters their immune responsiveness[25]; in one
small study an elemental diet appeared no better than
tube feeding a normal diet[26]. Furthermore, both total
parenteral nutrition and elemental diets alter bacterial
flora within the gut, so potentially the expression of
immune responses against bacterial products within the
gut lumen is likely to be altered. In this context it is of
interest that a combined approach (an elemental diet in
combination with the administration of non-absorbable
antibiotics to reduce the 'bacterial flora of the gut), was
shown to equal systemic corticosteroids in inducing rapid
remission in active Crohn's disease; remission was in-
duced within ten days[27].
An alternative approach to the study of food with-
drawal in inflammatory bowel disease is that used by
Hunter and his colleagues in Addenbrooke's Hospital, in
which a strictly regimented diet was tried to keep patients
in remission. Initially patients with Crohn's disease
achieved clinical remission by means of either total
parenteral nutrition or an elemental diet. Patients sub-
sequently reintroduced foods singly into their diets at
intervals, attempting to identify the particular foodstuffs
that initiated symptoms. Symptoms such as diarrhoea
and pain returned with anything from one to more than
ten different articles of diet, ranging from dairy products
and wheat to tap water. Long-term remissions have been
reported on subsequent maintenance of a restricted diet
excluding those foods that in the dietary trial caused
symptoms[28]. The difficulties in interpretation are obvi-
ous; in particular the attitude of the patients, and their
own belief in the role that food may play in their disease,
may well be important factors. Hunter and his colleagues
are now undertaking the daunting task of a controlled
evaluation of this approach.
Journal of the Royal College of Physicians of London Vol. 20 No. 1 January 1986 47
Conclusion
No simple relationship between eating particular foods
and disease activity in inflammatory bowel disease has
emerged. It remains a field in which the cynical disbeliev-
er in food allergy ? whose own reactions may have
become hypersensitive in response to media and patient
exposure ? remains confident. The data can best be
summarised as follows, (a) Patients with inflammatory
bowel disease have enhanced immune responses against
food antigens, but also against other antigens in the gut,
particularly bacteria and bacterial products, (b) Expres-
sion of these immune responses may contribute to inflam-
mation, and dietary alterations can induce remission. It
seems just as likely that changes in faecal consistency and
bacterial content are responsible for improvement, as that
the withdrawal of a specific food antigen is responsible.
Finally, however, there are striking geographical vari-
ations. Inflammatory bowel disease is a common problem
in the West, and rare in the Third World. Epidemiolog-
ical studies have shown that increasing westernisation
leads to a higher incidence of these diseases: in Polyne-
sians, Maoris and South African blacks ulcerative colitis
is becoming more common, perhaps with westernisation
of habits as previously rural people become urban-
ised[29]. The immigrant from India in the UK has an
incidence of inflammatory bowel disease which ap-
proaches that of the native Briton, although he is more
likely to have ulcerative colitis than Crohn's disease[30].
These emerging trends, as people of different races take
up similar life-styles, point convincingly to environmental
causes. While 'food allergy' remains the language of the
enthusiast, a 'major influence of the constituents of the
diet' seems likely to be an aetiological factor of great
significance.
This article is based on a paper read at the Conference on
Allergic Diseases held at the Royal College of Physicians in
March 1985.
References
1. Pearson, D. J. (1985) Journal of the Royal College of Physicians of
London, 19, 154.
2. Bienenstock, J. and Befus, A. D. (1981) Immunology, 41, 249.
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(1984) Archives of Disease in Childhood, 59, 326.
5. McConnell, R. B. (1972) Clinics in Gastroenterology, 1, 321.
6. Rask-Madsen, J., Hammersgaard, E. A. and Knudsen, E. (1973)
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10. Broberger, D. and Perlmann, P. (1959) Journal of Experimental
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11. Shorter, P. C., Cardogan, M., Spencer, R. J. et al. (1969)
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12. Lagerkrantz, R., Hammarstrom, S., Perlmann, P. et al. (1968)
Journal of Experimental Medicine, 128, 1339.
13. Falchuck, K. R. and Isselbacher, K.J. (1976) Gastroenterology, 70,
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14. Mee, A. J., Mclaughlin, J. E., Hodgson, H.J. F. et al. (1979) Gut,
20, 1.
15. Montieso, E., Fossey, J., Shiner, M. et al. (1971) Lancet, 1, 249.
16. Hodgson, H.J. F., Potter, B.J. and Jewell, D. P. (1977) Clinical
and Experimental Immunology, 29, 187.
17. Rabin, B. S. and Rogers, S. J. (1978) Gastroenterology, 75, 29.
18. Wright, R. and Truelove, S. C. (1965) British Medical Journal, 2,
138.
19. Pena, A. S. and Truelove, S. C. (1973) Gastroenterology, 64, 400.
20. Jewell, D. P. and Truelove, S. C. (1972) Gut, 13, 903.
21. Harper, P. H., Truelove, S. C., Lee, E. C. G. et al. (1983) Gut, 24,
106.
22. Harper, P. H., Lee, E. C. G., Kettlewell, M. G. W. et al (1985)
Gut, 26, 279.
23. Elson, C. O., Layden, T. J., Memchausky, B. A. et al. (1980)
Digestive Diseases and Sciences, 25, 42.
24. O'Morain, C., Segal, A. W. and Levi, A. J. (1984) British Medical
Journal, 288, 1859.
25. Harries, A. D., Davis, V. A. and Heatley, R. V. (1984) Gut, 25,
465.
26. Bos, L. P., Nuse, M. and Weterman, I. T. (1981) In Recent
Advances in Crohn's Disease, p.499. (ed. A. S. Pena et al.) The Hague:
Martinus Wighoff.
27. Saverymuttu, S. H., Hodgson, H. J. F. and Chadwick, V. S.
(1985) Gut, in press.
28. Workman, E., Alun-Jones, V., Wilson, A. J. and Hunter, J. O.
(1984) Human Nutrition, 38A, 469.
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25, Al 144.
48 Journal of the Royal College of Physicians of London Vol. 20 No. 1 January 1986
|
PMC005xxxxxx/PMC5371137.txt | Investigation of Coronary Artery Disease
M. C. PETCH, MD, FRCP
Consultant Cardiologist, Regional Cardiac Unit, Papworth Hospital, Papworth
Everard, Cambridge
The investigation of patients suspected of suffering from
coronary artery disease (CAD) is a subject of interest
because heart disease is common and potentially fatal. To
some extent we can predict who is going to die. Those
patients with severe CAD and badly scarred ventricles
have a worse prognosis than those with mild disease and
normal left ventricular functionfl ,2]. In anatomical terms
severe CAD means atheromatous narrowing of the left
main stem coronary artery or disease affecting all three
major branches?the circumflex, anterior descending and
right.
Coronary bypass surgery, a form of treatment designed
and undertaken to relieve angina, can improve survival in
patients with severe CAD[3,4], Although the Coronary
Artery Surgery Study[5] casts some doubt on this belief,
there are good reasons for thinking that the results of this
study do not apply to practice on this side of the Atlantic;
for example, those patients with left main stem lesions
were excluded and 22 per cent of those participating in
the randomised portion of the study had no angina.
It is obviously important to detect those patients with
severe CAD and scarred ventricles. This can be achieved
by left ventricular angiography and coronary arterio-
graphy but since it is impractical to undertake this
investigation on everyone, various screening tests have
been devised. American physicians receive regular advice
on 'investigative strategies'[6-8], and respond in a pre-
dictable fashion to a clinical problem such as chronic
stable angina or uncomplicated myocardial infarction. In
Britain our practice is more haphazard. Many physicians
admit to being confused by the panoply of cardiac
investigations now available and this confusion is com-
pounded by the uneven distribution of cardiological skills,
local enthusiasms and prejudices, and, always, restricted
resources. When reading the American literature we may
wonder whether our colleagues are influenced by their
system of remuneration; for them each investigation
attracts a fee; here, each investigation denies another
patient the opportunity of being investigated.
We may learn from the American experience. Two
general conclusions emerge from their reviews [6-8],
which are based on a wealth of original observations.
First, the sensitivity and specificity of any screening test
depend not just upon the diagnostic accuracy of the
investigation, but also on the population studied; even a
highly specific investigation will yield a number of false
positive results if it is applied to disease-free individuals.
Second, the greater the variety and complexity of the
investigations, the better is their predictive value, but at a
price that includes discomfort and inconvenience to the
patient and reduplication of information. Thus the inves-
tigation of asymptomatic patients is likely to be
unrewarding. False positive results will create alarm and
require further investigation in order to eliminate the
suspicion of heart disease. We should confine our atten-
tion to symptomatic patients; this generally means those
presenting with chest pain. Among them will be some
with typical cardiac pain for whom a minimum of
investigation is necessary to confirm the diagnosis and
advise on management. There will be others with atypical
pain for whom more extensive but selective investigation
will be required.
The stimulus for this review came from the recent
Consensus Conference on Coronary Artery Bypass Sur-
gery[9]. Although the conference was primarily con-
cerned with candidates for surgical treatment, it did
provide an opportunity to assess our investigative prac-
tice. The investigations can be conveniently classified as:
preliminary?those which may be undertaken in general
practice; intermediate?usually available in a District
General Hospital (DGH); specialist?usually confined to
a regional centre or teaching hospital.
Preliminary Investigations
An electrocardiogram (ECG) is invariably the first inves-
tigation requested in patients suspected of suffering from
CAD. However, the ECG is normal in uncomplicated
angina pectoris; moreover, the initial ECG is normal in
11 per cent of patients subsequently shown to have
definite myocardial infarction[10]. Nevertheless, the
ECG is worthwhile because it can give a definite diag-
nosis and any subsequent change may establish the
diagnosis with certainty.
Some routine haematology should be performed at this
stage because cardiac pain may be a presenting symptom
of other diseases, e.g. anaemia. Biochemical investi-
gations may include estimates of 'cardiac' enzymes and
serum lipids. However, a word of caution must be
sounded over the interpretation of cardiac enzyme esti-
mations. An erroneous diagnosis of cardiac disease is too
often entertained because an elevated creatine kinase,
aspartate transaminase, or lactate dehydrogenase level
was discovered, the cause of which was, respectively, an
intramuscular injection, liver damage or haemolysis.
Conversely, cardiac infarction may be thought to have
Journal of the Royal College of Physicians of London Vol. 20 No. 1 January 1986 21
been excluded by a normal result when in fact cardiac
damage had occurred but the blood sample had been
taken too early or too late to catch the abnormal rise in
enzyme level. Serum lipid estimations also have to be
interpreted with caution. There is no 'normal range', but
higher values are associated with a greater risk of CAD. A
knowledge of the lipid levels is also essential when giving
dietary advice.
Intermediate Investigations
Exercise Testing with Electrocardiography
Graded exercise on a treadmill or bicycle imposes an
increasing workload on the heart which, in patients with
CAD, may uncover ischaemia. Such testing is of limited
value in making the diagnosis of CAD. In asymptomatic
patients the false positive rate may be as high as 64 per
cent if the single electrocardiographic criterion of 1 mm
ST segment depression is used[ll]. In the Coronary
Artery Surgery Study[12] 89.4 per cent of men with a
history of definite angina had CAD; the probability of
detecting CAD was not significantly increased by a
positive exercise test. On the other hand, 39.6 per cent of
women with atypical angina had CAD but the exercise
test was misleading because 46 per cent of those sub-
sequently shown to have normal coronary arteries had a
positive test.
Exercise testing may be useful in management. Im-
portant prognostic information can be obtained in symp-
tomatic patients if multiple clinical observations are
made, viz. time to onset of symptoms or duration of
exercise, heart rate, blood pressure, recovery time, and
the timing and nature of any electrocardiographic
change. In general, early onset of angina, marked and
widespread ST segment depression, slow recovery, and
poor rise in blood pressure collectively indicate more
severe coronary disease[13-16] and a more limited prog-
nosis[14,17-21]. For example, McNeer and his col-
leagues[14], in a study of 1,472 patients, found that those
able to reach stage IV of the Bruce protocol, with no
significant electrocardiographic change, had a less than 1
per cent (one patient in 280) chance of left main coronary
stenosis and those who reached that level of exercise with
a heart rate of 160/min or more had a 99 per cent chance
of surviving one year. Theroux et al. [19] studied 210
patients following uncomplicated myocardial infarction
and found one-year mortality rates of 27 per cent in those
with exercise-induced electrocardiographic ST segment
changes and 2.1 per cent in those without. Dagenais et
al. [21] showed that patients only able to reach stage I of
the Bruce protocol had a five-year survival rate of 52 per
cent; the comparable figures for higher workloads were
stage II?73 per cent, stage III?86 per cent. Of course
these studies can be criticised. Exercise testing may be
poorly reproducible[22]. Many patients with the worst
prognosis cannot get as far as the treadmill, let alone
embark on any exercise. If testing is undertaken too late
after infarction some of the high-risk patients identified
by Theroux et al. will already have died.
The exercise test is thus of doubtful value in diagnosis
and superfluous in the management of the patient with
typical limiting angina because such a patient should
proceed directly to coronary arteriography. However, an
exercise test is valuable in those patients with CAD and
mild symptoms because limited exercise tolerance and
marked ST segment change should prompt referral for
coronary arteriography.
Nuclear Imaging
Most DGHs possess a gamma camera and thus have the
capacity for cardiac imaging, given some additional
expenditure on equipment for data collection and pro-
cessing. "Technetium-labelled pyrophosphate is taken up
by a recent myocardial infarct. This investigation has
little advantage over the usual electrocardiographic and
enzyme markers of infarction and so is little used.
201Thallium outlines perfused myocardium and is thus
useful in detecting infarcted areas at rest, and ischaemic
areas which develop on exercise. This knowledge can
enhance somewhat the sensitivity of diagnosis of
CAD[23,24] but cannot pick out those with more ad-
vanced coronary disease much more reliably than
straightforward stress testing[25-27]. The use of thallium
imaging is perhaps best reserved for those patients with
atypical chest pain and a low probability of CAD in
whom a negative test would obviate the need for angi-
ography [8].
Radionuclide left ventricular angiography using "tech-
netium and either a first-pass or gated-equilibrium tech-
nique is an excellent screening test of ventricular
function. Borer et al. [28] were the first to show that left
ventricular function deteriorated during exercise in
patients with CAD. But this response is non-specific and
occurs in many cardiovascular disorders, including hy-
pertension. Nevertheless, exercise-induced abnormalities
of ventricular function provide objective confirmation of
cardiovascular disability. For example, in the patient with
established CAD whose symptoms remain difficult to
interpret, an exercise-induced deterioration in left ven-
tricular ejection fraction (LVEF) would imply that the
symptoms had an organic basis and required further
treatment.
Radionuclide angiography can also identify those
patients with poor left ventricular function following
myocardial infarction. These patients fare badly[29-33].
The first year mortality for those survivors with poor
(LVEF less than 20 per cent), moderate (LVEF 20-39 per
cent) and good (LVEF greater than 40 per cent) left
ventricular function was respectively 33 per cent, 19 per
cent and 3 per cent in one study[33]. This information
enables the physician to give a more accurate prognosis
and refine his selection of those for angiography. In the
future it is possible that two-dimensional echocardio-
graphy will provide similar information[34], quite apart
from the value of this investigation in other forms of heart
disease.
Thallium imaging of the myocardium has not gained
widespread acceptance in the UK. The isotope is expens-
ive and the information gained is often of limited value.
However, radionuclide ventriculography is helpful in I
22 Journal of the Royal College of Physicians of London Vol. 20 No. 1 January 1986
identifying patients with poor left ventricular function
and should be more widely used.
Specialist Investigation
In practice this means left heart catheterisation, left
ventricular angiography and coronary arteriography.
The investigation demands expensive equipment, in-
volves a minimum of five trained people (doctor, two
nurses, radiographer, technician) and takes about 30
minutes. The procedure is mildly unpleasant since it is
performed under local anaesthesia but the distressing hot
flush associated with the injection of 30-50 ml of contrast
medium can be avoided by using non-ionic media. There
is a small morbidity (e.g. local arterial problems, myocar-
dial infarction, arrhythmias), and mortality; there have
been two deaths in the last 2,500 cases at Papworth
Hospital. Most patients are admitted to hospital, al-
though the number of day cases is increasing.
Coronary arteriography is the gold standard in making
the diagnosis of CAD. In most British centres over 90 per
cent of patients thought to have CAD on clinical grounds
will turn out to have obstructive lesions of their main
coronary arteries. For those patients with normal coron-
ary arteries a diagnosis of coronary spasm may be
considered, but most cardiologists will return to the
bedside, take the history again, and conclude that the
pain had some other cause.
The extent and severity of the coronary lesions,
together with the amount of damage to the left ventricle,
determine the prognosisfl ,2]. The information gained by
arteriography is thus invaluable in management but not
essential. Most patients with limiting angina despite
medical treatment should undergo arteriography in order
to decide about the possibility of surgical treatment. The
younger and more active the patient the more likely is he
to need bypass surgery to maintain his life-style. Another
common example is the asymptomatic patient who has
had an uncomplicated myocardial infarct. One per cent of
patients investigated following a myocardial infarction
will have a left main stem stenosis and 26 per cent will
have disease of all three coronary vessels[35]. The re-
mainder, nearly three-quarters of such patients, will not
have severe disease. They should receive careful medical
management but will not require surgery either for
symptoms or for survival. A knowledge of their coronary
anatomy will contribute little to their management; clini-
cal assessment coupled with exercise testing or radionu-
clide angiography will identify those at high risk.
The view that some patients with CAD might not
require angiography is unfashionable at present. How-
ever, those cardiologists in active clinical and investiga-
tive practice often experience difficulty in deciding how to
manage a man with angina and only moderate coronary
disease. Time and again the decision is most easily made
in out-patients when others (nurses, junior staff, etc.) are
not present and both physician and patient can talk freely
on equal terms?both being dressed and seated. Only
when the details of a patient's life-style, hopes, fears and
ambitions are understood can a sensible decision about
management be made. Coronary arteriography is the
most important investigation for patients suffering from
CAD but it is always an adjunct to clinical judgement.
Other specialist investigations are available. The
patient may be subjected to a variety of physical stresses
(dynamic or isometric exercise, atrial pacing, cold pres-
sor) in the cardiac laboratory and these may be coupled
with studies of myocardial metabolism, e.g. lactate bal-
ance. However, these are mainly research procedures.
Most cardiac laboratories are busily engaged in undertak-
ing as many coronary arteriograms as possible.
How Many Investigations?
This question may be impossible to answer but it does
merit thought. Cardiologists are overwhelmed by re-
quests for the investigation of patients with CAD, where-
as general practitioners only see a few such cases
annually.
Angina pectoris is usually the first manifestation of
CAD. Several estimates of its prevalence have been
attempted. The Whitehall study, which is exemplary and
representative of its kind, found that 4.8 per cent of men
aged 40-64 years admitted to symptoms suggestive of
angina[36]. But this may be an over-estimate of the need
for investigation because these men were not seeking help
but responding to a questionnaire. Moreover, angina
remits. Men who have chest pain one year may not have
it the following year; in the Framingham study remission
occurred for at least two years in 32 per cent of men[37].
A truer estimate of the prevalence of angina might
come from studies in general practice such as that
instigated by Julian in the Northern region[38]. In a
population of 125,000, 336 patients were identified from
practice records, sick notes, etc. The recorded rate in men
aged 30-59 from those practices with the highest report-
ing rate was 1.6 per cent?a figure not inconsistent with
the Whitehall one of 4.8 per cent if the methodological
and age differences are taken into account. However, the
crude figures of 336 per 125,000 give a prevalence rate of
only 0.27 per cent or 2.7 per 1,000 population. The
second national study of morbidity in general practice[39]
found that the prevalence of angina per 1,000 population
was 3.4 for men and 3.0 for women. Thus there may be
some 3,000 patients with unremitting angina per million
population in the UK at present. Because they are elderly
or infirm, many will not require further investigation. A
minority, 22 per cent in the study quoted above[38], will
have angina that is severe enough to merit further action.
These crude calculations suggest that 600-700 patients
per million might require investigation now.
The annual incidence of new cases of angina is also
unknown. The same Northern study[38] found 14 new
cases of severe angina in the year before the survey,
giving an annual incidence of 112 per million population.
These are severe cases and it may be assumed that most
would require further investigation.
Myocardial infarction is the other common manifes-
tation of CAD. In the second general practice study the
figures per 1,000 were 4.1 for men and 3.0 for
women[39]. Because patients with myocardial infarction
are often easier to identify than those with angina pec-
Journal of the Royal College of Physicians of London Vol. 20 No. 1 January 1986
toris, further estimates of the incidence are available: for
example in Edinburgh in one year 1,367 episodes in
which the victim was seen by a doctor occurred in a
population of approximately 500,000 persons[40]; in
Oxford there were 362 cases in 375,000 persons but 140
patients died before being seen by a doctor[41], These
estimates of 2.7 and 0.6 early survivors per 1,000 popu-
lation, together with the Tower Hamlets study[42] which
gave an intermediate figure, suggest that there might be
an additional pool of some 1,600 patients per million
population who might stand to gain from further investi-
gation of their CAD.
These imprecise estimates were discussed at the Con-
sensus Conference[9], Only one firm conclusion could be
drawn: a minority of patients suffering from CAD can be
adequately investigated given our present resources.
There is a pressing need for more accurate information,
not so much about the present cardiological activities of
DGHs and specialist centres, which is a relatively simple
task, but rather about the potential pool of CAD victims
who cannot be assessed because their general prac-
titioners know that there is no point in referring them.
Conclusion
The patient who is limited by angina pectoris despite
medical treatment requires a coronary arteriogram.
Patients, especially younger ones, with less severe angina
should be offered arteriography if they have a 'positive'
exercise test. Patients with atypical pain which defies
clinical diagnosis may be reassured by intermediate inves-
tigations but will often require arteriography, especially if
their livelihood is at stake.
Following uncomplicated myocardial infarction those
patients who have localised damage as judged by clinical,
electrocardiographic and enzymatic criteria need no fur-
ther investigation. Risk stratification may be accom-
plished by radionuclide angiography (for those with poor
left ventricular function on clinical grounds) or exercise
testing (for those with good left ventricular function).
Patients with refractory angina or further episodes of
cardiac pain should undergo arteriography, especially if
they have good left ventricular function and a positive
exercise test.
This review is necessary because we lack a reliable,
simple, harmless, painless and cheap method of confirm-
ing the diagnosis of CAD. In the unlikely event of such a
test becoming available every hospital would still need a
physician/cardiologist blessed with that elusive quality?
clinical judgement.
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24 Journal of the Royal College of Physicians of London Vol. 20 No. 1 January 1986
|
PMC005xxxxxx/PMC5371138.txt | The Prevention of Huntington's Chorea.
The Milroy Lecture 1985
?^1
PETER S. HARPER, dm, frcp
Professor and Consultant ir(Medical Genetics! University of Wales College of Medicine, Cardiff
When Dr Gavin Milroy endowed this lecture, I doubt if
he envisaged that inherited diseases would come to form a
challenge equal to that which infectious disorders posed
for nineteenth-century physicians.
My subject is the genetic disorder Huntington's chorea
(HC), which epitomises many of the problems that we
face in medical genetics and illustrates the common
ground that exists between genetics and epidemiology.
Both genetics and epidemiology are scientific disci-
plines with a theoretical basis that, in genetics especially,
has widespread applications for all living organisms. Both
are also clinical specialties, and the emergence of the
medical geneticist as a specialist in his own right has been
one of the major developments of the past 15 years.
In both fields prevention is the primary aim and in both
the emphasis extends beyond the individual patient to the
family as a whole and to the general population.
Huntington's chorea follows autosomal dominant in-
heritance, passing on average to half the offspring of an
affected person, but sparing those of a person who
remains free from the disease. It is perhaps the most
serious disorder of adult life that faces the medical
geneticist involved in genetic counselling and prevention,
and the physician and neurologist who are still largely
helpless in influencing its coursefl]. The combination of
progressive involuntary movements, general physical dis-
ability, serious mental deterioration and the hereditary
nature of the disorder, create an overwhelming burden
for most of the families in which it occurs.
The family in Fig. 1, the first with Huntington's chorea
that I encountered on coming to work in Cardiff 14 years
ago, epitomises the problem of prevention to be faced. All
members are descended from a single individual who
came to work in Wales around a century ago[2]; the
house where he lived still stands in the hamlet of Mynyd-
dislwyn, high on a ridge between two mining valleys. His
descendants moved down into the valleys and almost all
of them live there still, many, affected with the disorder
and many more at risk.
It soon became clear to me that HC was a major
problem not just in this small area, but throughout South
Wales, and that a major initiative was needed if its full
extent was to be known.
We decided to concentrate initially on the geographi-
cally restricted area of industrial South Wales rather than
attempt ? total ascertainment throughout the scattered
rural areas of West, Mid- and North Wales. The popu-
lation in our study is dense, relatively stable, with a
limited number of specialist services and within easy
travelling distance of our centre in Cardiff.
Fig. l. A large South Wales kindred with Huntington's chorea. The ancestor of this family originates from North Tawton, the same
Devon village in which Dr William Budd studied the transmission of typhoid fever\2].
Journal of the Royal College of Physicians of London Vol. 20 No. 1 January 1986
At the end of the first phase of our study we found that
the number of both affected individuals and apparently
unrelated kindred was much greater than we had envis-
aged, while the number of those at high risk was close to
1,000[3,4].
The results of this study are summarised in Table 1.
Table 1. Huntington's chorea in South Wales.
Prevalence 7.6 per 100,000
Total living affected 130
Total living high-risk relatives in area 980
Annual new cases (mean 1960-70) 9.3
Mean duration of illness (onset to death) 15 years
Number of proven new mutations 0
The prevalence of HC in South Wales is indeed high in
comparison with most other British surveys; leaving aside
those selected for small foci of the disorder, only the East
Anglian study of Caro shows a higher prevalence[5].
More important for prevention is the large number of
relatives at high risk, about eight times the number of
those actually affected. Only those with an age-adjusted
risk of greater than 1 in 10 are included here, but this
large number, around 1,000 in South Wales, illustrates
how much greater an impact the disorder has than would
be expected from its prevalence. Only a minority of those
at risk will develop the disorder, but all will be 'affected'
by it in one way or another.
The mean duration of the disorder from onset to death
is 15 years, of which the last five years represent severe
disability; half of our patients required long-term hospital
care, with an average duration of four years, but half
were cared for at home throughout their illness, a reflec-
tion of the often unnoticed (and uncosted) burden borne
by the families[6]. Not all affected individuals actually
died from HC; later onset cases in particular not infre-
quently died of unrelated illnesses and we know of
instances where HC was not diagnosed during life.
Table 1 also shows that we have found no proven
example of mutation[7]; some isolated cases may be the
result of mutation, but we cannot be certain, either
because parents died relatively young, or because of
uncertainty over paternity. One can safely say that new
mutations represent a very small fraction of all cases of
HC, and that if transmitted cases were to be prevented,
the disorder would become exceedingly rare.
The rarity of mutation agrees well with another finding
in our South Wales population[7]?the lack of an adverse
effect of the disorder on fertility. In fact we found an
increased mean family size, as have some (but not all)
previous investigators[8]. This increase is for both males
and females, with a relative increase over healthy sibs and
an absolute one over the corresponding general popu-
lation (Fig. 2), and has persisted over the entire period for
which our records extend. We have studied in detail the
pattern of family building in our population, but there is
no evidence of a peak around or just preceding onset of
the disorder, as might be expected if sub-clinical beha-
vioural effects were involved.
Although we cannot fully explain the observed increase
in fertility seen in HC, we can certainly document why
there has been no decrease until the present time. Infor-
mation was obtained by personal interview of a sample of
100 patients and their spouses, and a separate random
sample of 100 first-degree relatives. Only one-third of the
first group had had professional counselling, and thus had
a clear understanding of the hereditary nature of the
disorder, before their family was complete; the situation
for the children at risk was somewhat better; two-thirds
had some factual knowledge, but this lack of information
clearly indicated the need for systematic genetic counsel-
ling for these families[9].
The same survey illustrated how difficult many families
find it to tell their offspring about the genetic nature of the
complaint, even if they recognise it themselves. Seventy
per cent of parents stated that their children ought to be
told before having their families; only 7 per cent were
definitely against this course. Yet, of these same families,
only 30 per cent had in fact told their grown-up children.
We find that families frequently need professional help in
this. Often initial information from the parents is fol-
lowed-up by giving the children an opportunity to ask
fuller questions; sometimes, when a parent finds the task
too difficult or painful, the whole process is undertaken.
Genetic Counselling in Huntington's Chorea
In dealing with HC, the counsellor is faced by a unique
combination of problems. The burden imposed by the
severity of the disorder, the lack of effective therapy or
prediction and the frequency of social and psychiatric
problems arising directly or indirectly from the disorder
all contribute to the difficulties of genetic counselling.
Perhaps the largest factor, however, is the late and
variable onset of the condition, illustrated in Fig.
3 [ 10,11 ]. The two curves show the chance of someone
with the HC gene showing the disorder at a particular
i 1 1 r r i i i
1900 1910 1920 1930 1940 1950 1960 1970
Fig. 2. Frequency of choreic genes weighted according to risk
compared with births in the related population of Glamorgan
and Gwent, 1900-70, expressed on a log scale (five year
moving averages used to smooth curves).
Journal of the Royal College of Physicians of London Vol. 20 No. 1 January 1986
age, and the remaining risk for an individual with an
affected parent. It can be seen that this risk is little short
of 50 per cent during the reproductive period; for those
whose parent is unaffected, the use of this curve in risk
estimation may be very valuable since their risk will be
close to half that of their parent; where the parent is
relatively elderly, the risk for their child will be corre-
spondingly small.
Our South Wales study was designed to be the founda-
tion for systematic genetic counselling in our families with
HC, a programme which has been going for about 10
years. This has involved a different approach to that
required for a simple prevalence study, and, in particu-
lar, an effective recording system suitable for prospective
use in a service setting was needed[12]. In setting up such
a system we found it necessary to greatly simplify our
original study record, and to evolve a register which
allows both the follow-up of individuals through an easily
completed form, with adjustment of risk estimate accord-
ing to age and changes in the kindred, and the production
of statistical data for monitoring trends in our population
at risk. From the beginning we have avoided placing
names, addresses or other identifying information on our
computerised record, feeling that, however efficient the
confidentiality of a system, we should not allow any
unease to jeopardise our relationship with the families.
One group of particular importance, but often ignored,
is those individuals whose risk has decreased to minimal
levels, either as a result of their own or their parent's age.
We do not attempt to follow actively those whose risk is
less than 1 in 10, but we do try to ensure that they know
the risk is low; a surprising number have an exaggerated
idea of their risk, or fear that HC may occur in their
children even if they themselves are spared.
A consistent line that our group has always taken is that
genetic counselling should not be directive, though we try
to provide as detailed as possible information about the
nature of the disorder, the range of severity and age at
onset, and possible future developments, and we now
frequently suggest to younger individuals or couples that
they delay plans for childbearing in view of the possibility
of predictive tests. This non-directive approach is criti-
cised by some, but we feel that in most instances it would
be neither justified nor effective to advise those at risk not
to have children; the facts must be weighed and decisions
made by each couple in the light of their own situation.
Genetic counselling is particularly difficult in those
cases where a person at risk has grown up unaware of the
family disorder, commonly as a result of family break-up.
It may be questioned whether it is desirable to trace and
inform such individuals about their risk, but our experi-
ence of those who have not been informed and only
learned of the situation in later life, leads us to the view
that accurate information, sensitively given, is preferable
to ignorance or to finding out later in a less suitable way.
The timing of genetic counselling is another difficult
issue. Clearly, to be of any use it must be given before
child-bearing, but how far beforehand is debatable.
Again our own experience suggests that giving at least
some information early, at around 15-16 years, may
avoid causing greater distress, as can happen if first
knowledge comes at the time of engagement or marriage.
Such initial information need not be detailed, but it can
form a foundation for later, more detailed genetic coun-
selling. It is surprising how much quite young children
often prove to know, and how a preliminary discussion
may permit more open acceptance of a situation pre-
viously unmentionable within the family.
Long-Term Prevention
Although the main role of genetic counselling in HC is, as
with other genetic disorders, to help individuals in their
decisions, the possibility of achieving a general reduction
in future incidence of the disorder is an issue of the
greatest importance. The combination of total ascertain-
ment, systematic genetic counselling and prospective
study has made it feasible to examine these aspects in
South Wales to an extent that has not been possible
elsewhere because we are dealing with data on a represen-
tative and almost complete population of families at risk,
rather than a selected group that has sought genetic
counselling[13].
Study of our families' attitudes to genetic counselling
showed that the majority of young individuals at risk
intended to limit their families in the light of information
about the disorder[9]. Such intentions, however, may not
be translated into action, and the only way of telling what
is happening is to document the births in the population
at risk[ 14, 15]. Fig. 4 shows that this has indeed occurred,
and provides a striking contrast with the relatively con-
stant rate in the past, as shown in Fig. 2. To what extent
Age (years)
Fig. 3. Age at onset and genetic prediction in Huntington's
chorea, based on South Wales data[ 10,11]. Solid line?
probability that an individual with the HC gene will show the
disorder at a given age. Broken line?probability that a healthy
individual with an affected parent has the HC gene at a given
age.
Journal of the Royal College of Physicians of London Vol. 20 No. 1 January 1986
this change is related to the genetic counselling that most
individuals at risk have received is uncertain, but the
striking reduction in births over a relatively short period
is of considerable significance, particularly in view of the
lack of any form of predictive or prenatal detection for the
disorder.
The trends shown in Fig. 4 are, for recent years,
naturally based on predicted rather than actual cases,
being derived from the number of births at risk in each
year and the degree of risk of each birth based on the age-
adjusted risk for the parent. Thirty years and more will be
required before we can be sure whether these predicted
cases of HC will actually develop the disorder, unless an
accurate method is discovered for determining the pres-
ence of the gene. So far all the work described has been
done in the absence of such a test. However, major
developments in gene mapping are likely in the very near
future to change our approach to prediction and preven-
tion, and may well cause problems, as well as solving
them, in genetic counselling.
Gene Mapping in Huntington's Chorea
The possibility of identifying the HC gene by means of
genetic markers has been considered for a number of
years. Several studies have used the classical polymorphic
markers, principally blood groups, serum proteins and
red blood cell enzymes, to investigate this; all, including
an analysis of our South Wales families, were nega-
tive[16-18].
The limited number of available markers inhibited
further work in this field until the recognition of DNA
sequence polymorphisms, which provide an abundant
source of genetic variation that can be studied using
recombinant DNA techniques. Nonetheless, the identifi-
cation of a closely linked DNA probe in the first series of
randomly chosen markers came as a surprise, and has
provided a major advance that logically was not expected
for several years.
The marker concerned (G8) is located on the short arm
of chromosome 4 and a study in two large kindreds
showed firm evidence of close genetic linkage[19]. Subse-
quent study of the probe in our South Wales families has
confirmed this linkage. The G8 probe and subclones
derived from it detect a variety of polymorphisms; the
best documented is with the restriction enzyme Hind III
(Fig. 5) and shows two variable sites which can be
combined to give four 'haplotypes' (A, B, C and D). A
further polymorphism with the enzyme EcoRl detects
two variants at almost equal frequency, while less fre-
quent polymorphisms are seen with other enzymes (Fig.
6). Taking these polymorphisms together, over 80 per
cent of individuals are heterozygous at the G8 locus which
means that, in principle at least, prediction in some form
would be feasible for over 80 per cent of individuals if this
marker were to be used.
Studies in our South Wales families[20, 21] suggest
that the linkage is indeed close (around 2 per cent
recombination between marker and disease); we have
found no suggestion of heterogeneity involving more than
one locus. However, the marker is not so close as to be in
any way functionally related to HC, and while the linkage
is close within families, there is nothing to suggest that in
HC individuals overall any G8 type is more frequent than
in the general population. In most families studied the
disease is transmitted along with the commonest 'A'
haplotype; where a rare marker type is transmitted with
the disease, as seen in Fig. 7, a much clearer pattern can
be seen of how the two are co-inherited.
The unexpected closeness of the linkage has raised the
possibility of its application in prediction; families in
which the HC gene is travelling with one of the rarer
haplotypes, as in Fig. 7, show how this could be feasible.
Fig. 4. Decline of births at risk for HC in South Wales.
A. Predicted new cases of HC per year. B. General population
birth rate. C. Ratio of A to B.
Haplotypes AD AA AA AC BD
Hind III Allele 1 ^ 17.5kb
Site 1 Allele 2 ? W 15.0 kb
Allele 1 mm ?> 4-9kb
Hind III Allele 2 mm ?P ? W < 3-7kb
Site 2
Fig. 5. Hybridisation of the probe pk082 to Hind III digested
human genomic DNA. After digestion of the DNA with the
restriction enzyme Hind III, the DNA fragments were separat-
ed by electrophoresis on a 0.7 per cent agarose gel. Blotting of
the DNA on to nitrocellulose filters was performed by Southern's
method. The haplotypes observed in each individual were
assigned previously. (Preparation by Miss Sandra Youngman.)
10 Journal of the Royal College of Physicians of London Vol. 20 No. 1 January 1986
A person must be heterozygous at both the marker and
disease loci if any prediction is to be possible for children;
for an affected individual homozygous at the marker locus
there is no means of distinguishing which haplotype is
travelling with the HC gene.
The use of this approach in prediction will clearly
depend on an accurate knowledge of the distance between
marker and disease, as well as on complete proof that
there is not more than one separate HC locus. Further
polymorphisms at or around the G8 locus will also be
needed to ensure that all individuals are heterozygous and
thus informative; for greater accuracy 'flanking' markers
on each side of the HC locus will be needed. All these
aspects are being actively pursued at present[22], but they
will not remove one major drawback for prediction: the
necessity for typing a number of key family members in
order to give a prediction for a particular individual.
The magnitude of this drawback is illustrated by the
pedigrees shown in Fig. 8, and by the data from our
South Wales families related to. this (Table 2). Fig. 8
shows the family structures needed to give a prediction for
an individual at 50 per cent risk. At least one grandparent
must be living for this to be feasible, in order to tell
whether the person at risk has inherited from the affected
parent the gene that has come from the affected grandpar-
ent?or the one from the healthy grandparent. Table 2
shows that only a small proportion of young adults have
the appropriate family structure; the two series show the
situation for a consecutive series of 100 individuals (or
their spouses) at risk who were pregnant, as well as for the
lareer bodv of individuals at high risk between the aeres of
20 and 45[23],
It is thus clear that prediction of presence or absence of
the gene will not be feasible for the great majority of
people at risk, even if the available markers are developed
to be fully informative and accurate. This situation is only
likely to change when a test is developed that will identify
a specific defect in the HC gene of a single individual,
something that is still a long way off.
However, this apparently pessimistic situation changes
if we look at the same family structures but ask a different
question, i.e. is it possible to predict for the pregnancy of
a person at risk, rather than for the person? Fig. 9 shows
the various possibilities, and indicates that we can give
useful information without the presence of the grandpar-
ental generation; the fetus now represents the third
generation, and only a parent of the person at risk is
needed. Our data in Table 2 show that this type of family
structure is in fact present in around 90 per cent of cases,
so that one is able to make a prediction for the pregnan-
cies of most of those individuals where one can predict
about themselves. Essentially it answers the question: has
the fetus received a marker gene from its at-risk parent
that came down from the healthy grandparent, in which
case it should be unaffected (Fig. 9(ii)), or has the marker
from the affected grandparent been transmitted, in which
case the pregnancy is at the same 50 per cent risk as the
parent (Fig. 9(i)).
It should be emphasised that such a prediction does not
influence the risk situation for the parent; this may well
be an important factor in the decisions of couples in
future application of predictive tests. Equally, a predic-
Allele 1 -m* mm w 5.6Kb
-5.. .
Allele 1
Allele 2
14.5kb
9.1kb
^nni|^
Allele < W W 9 ? 1.6Kb
Allele 2
2'4Kb Allele 2
0.7Kb
Fig. 6. Polymorphisms shown by DNA probe G8 with restriction enzymes (a) EcoRl; (b) Pst 1; (c) Nci 1.
x 104
Fig. 7. A family with Huntington's chorea in which the
disease allele is segregating with the 'B' G8 haplotype.
Journal of the Royal College of Physicians of London Vol. 20 No. 1 January 1986 11
Table 2. Frequency of pedigree structure in South Wales families at risk for HC. A?Adults at greater than 10 per cent genetic risk,
age 16-45. B?Consecutive series of pregnancies of individuals at greater than 10 per cent risk.
Affected or At least Affected At least one Affected sibs
at risk one parent grandparents grandparent living
parent living living living living
No. No. (%) No. (%) No. (%) No. (%) No. (%)
A. Adults at risk:
Affected parent
Affected grandparent
Total
B. Pregnancies at risk:
Affected parent*
Affected grandparent*
Total
344 152(44.2)
293 263(81.8)
637 423(66.4)
67 38(56.7)
33 28(84.8)
100 66(66.0)
265(77.0) 7(2.0)
282(96.3) 25(8.5)
559(87.8) 32(5.0)
61(91.0) 2(3.0)
28(84.8) 0(0)
89(89.0) 2(2.0)
40(11.6) 66(19.2)
57(19.5) 1(0.34)
99(15.5) 67(10.5)
12(17.9) 3(4.5)
7(21.2) 0(0)
19(19.0) 3(3.0)
^Relationship to pregnant individual (or spouse) not to fetus
tion of this type is incomplete in that 'abnormal' predic-
tion indicates no more than a 50 per cent risk.
How far are these possibilities for prediction likely to
become part of clinical practice and genetic counselling?
So far, those groups studying the G8 probe in families
have not applied it in prediction, taking the view that it is
essential first to document the potential error rate, to
exclude heterogeneity, and to discuss widely with families
and clinicians the ethical and practical aspects of its
possible use in prediction. Once these issues are resolved,
there seems little doubt that there will be requests from
family members for prediction, and that this will face all
involved with difficult problems.
Previous surveys of relatives have shown that a ma-
jority would wish to have a predictive test (58 per cent in
our own randomly chosen sample[9], higher in some
surveys of more selected groups). Surveys carried out
since the discovery of the linked marker are broadly
similar, but it would not be surprising if some of those
responding positively when they knew a test did not
actually exist were to change their minds when confronted
with a test actually available.
So far, discussion of prediction has centred on the
problems of telling an apparently healthy person that he
will almost certainly develop a serious and untreatable
disorder at some future time. However, as this is not
likely to be practicable for more than a small proportion
of such individuals because of pedigree structure, I think
Fig. 8. Pedigree structures required in prediction for individuals at risk of HC (individual requesting prediction arrowed).
(i) Both grandparents are living. The affected parent has received HC along with the A ' marker type from the grandparent; since the
child has also inherited the 'A ' marker, he would be predicted as affected, in the absence of recombination.
(u) Here the offspring has inherited the 'B' marker type from his affected parent. This has come from the unaffected grandparent, so a
prediction of normality would be made.
(in) Neither grandparent is living. Prediction is impossible, since although the individual at risk has received the 'B' marker type
from the affected parent, it is not known whether this came with the HC gene or from the unaffected grandparent.
(iv) The affected grandparent is dead but must have carried the 'A ' marker and transmitted it with HC to his affected son. Thus a
normal prediction is possible for the individual at risk.
12 Journal of the Royal College of Physicians of London Vol. 20 No. 1 January 1986
it may prove more helpful to take a different view of
prediction. The aim would be not so much to predict the
presence or absence of the gene in the person at risk, but
rather to give the option to such a person of having
children likely to be free from a risk of the disorder. It is
quite possible that a proportion of those who would not
wish to have any prediction for themselves might wish to
have prediction in pregnancy, particularly if they knew
that such prediction would not have implications for
themselves.
It is too early to know what attitudes will be encoun-
tered, indeed, it is likely that these attitudes may change
quite rapidly as family members become aware of, and
adjust to, the new possibilities. One factor that will be
highly relevant is the development of first trimester
prenatal diagnosis using chorion biopsy[24], which allows
a decision to be made regarding termination of an
affected or at-risk pregnancy before 12 weeks' gestation,
in contrast to amniocentesis, where a diagnosis is often
not possible until 18 weeks. Preliminary experience from
families at risk for Duchenne muscular dystrophy, where
similar decisions have to be made concerning male
pregnancies at 50 per cent risk, suggests that for some
couples the early timing of decisions is a critical factor in
determining acceptability. We have studied the G8 probe
in chorion biopsy samples and shown that, using this
technique, typing of the polymorphisms is indeed feas-
ible[25]. The proportion of couples taking this approach
remains to be seen. Therefore, in my view it is important
that the families are made aware of the full range of
options, and that they can choose whichever they consider
best for themselves, including the option of having no
tests at all.
Future Developments
So far the localisation of the HC gene has been viewed in
terms of prediction and prevention, but it also provides
hope for isolation of the HC gene itself, and for studying
the mutational abnormalities that occur in the gene to
produce the disease. This would also open the way to
identifying the specific gene product of the HC locus,
something that conventional biochemical and neuroche-
mical research has not yet achieved. In fact, such work
need not await the isolation of the HC gene, though
various techniques of analysing the G8 region of the
genome are currently being applied. It is already possible
to test 'candidate genes' by means of their localisation.
Thus an increasing number of gene probes involving
important neurotransmitter functions are already known,
while many others studied in experimental species are
thought to be highly conserved throughout evolution; if
such genes are not localised in the same region as G8,
they are unlikely to be causally involved with HC; if they
are, they will at least deserve further study.
The expression of DNA sequences from the G8 region
can also be studied by the construction of 'libraries' of
cDNA derived from messenger RNA in tissue likely to
express the HC gene. Thus any sequences that prove both
to have the appropriate chromosomal location and are
expressed in basal ganglia would merit close attention.
Localisation of the HC gene should provide the key to
fuller understanding of the disorder; this in turn may
provide a rational basis for therapy and, possibly, for
measures that might postpone or modify the course of the
disease in those gene carriers as yet unaffected. Once this
becomes feasible, the outlook for prevention would be
AB
O
cc
AB
O
CC
?0
0-
O
cc
AC
O
DD
AC
O
DD
AC
O
DD
AC
o
DD
O
?
AD
9
?
CD
9
?
CD
?
CD
Fig. 9. Pedigree structures for prediction in a pregnancy at risk.
(i) Although no prediction can be made for the parent at risk, the fetus has inherited the 'A ' marker type from the affected grandparent
and is thus at the same 50 per cent risk as is the parent.
(ii) The fetus has here inherited the 'C' marker type from the healthy grandparent; HC can thus be excluded, in the absence of
recombination.
(in) No prediction can be made for the fetus since both grandparents are dead.
(iv) HC can be excluded in the fetus, since it has inherited the 'C' marker from the healthy grandparent, as in example B.
Journal of the Royal College of Physicians of London Vol. 20 No. 1 January 1986 13
entirely different. There would be a direct advantage for
those genetically affected to know in advance, and the
potential ethical conflict between knowledge helpful for
genetic counselling but traumatic for the person con-
cerned would be resolved. All of us involved in genetic
counselling for HC hope that such therapeutic develop-
ments will follow closely on the availability of predictive
tests though, realistically, it seems likely that there will be
an interim period during which prediction will be feas-
ible, but therapy ineffective.
How far then have we come along the road to preven-
tion of Huntington's chorea? A little way certainly, but
there is still far to go. We have seen that a striking change
in births at risk can occur in the complete absence of any
tests of prediction or any measure other than genetic
counselling, and we now have a DNA marker which,
while far from perfect, is a first step towards accurate
prediction and the isolation of the HC gene itself.
As new molecular developments occur during the
coming years, it will be essential to place them in the
context of careful clinical and epidemiological research,
so that we can accurately assess their impact on patients
and families and can ensure that they are applied wisely.
Acknowledgements
I would like to express my gratitude to Miss Audrey
Tyler, social worker, and Mrs Pat Jones, nurse-field-
worker, for their devoted work throughout this study as
well as to Doctors David Walker and Oliver Quarrell,
clinical research fellows, and Dr Robert Newcombe and
Miss Kathleen Davies of the Department of Medical
Statistics. Miss Sandra Youngman was responsible for
the DNA analyses. The work described has at various
times been supported by the DHSS/Welsh Office Small
Grants Committee, the Medical Research Council and
the Association to Combat Huntington's Chorea. ?
References
1. Hayden, M. R. (1981) Huntington's chorea. Berlin: Springer
Verlag.
2. Harper, P. S. (1976) Journal of the Royal College of Physicians of London,
10, 321.
3. Walker, D. A. (1979) Huntington's chorea in South Wales. MD
Thesis, University of Liverpool.
4. Walker, D. A., Harper, P.S., Wells, C. E. C., Tyler, A., Davies,
K.J. and Newcombe, R. G. (1981) Clinical Genetics, 19, 213.
5. Caro, A. J. (1977) Huntington's chorea. A genetic problem in East
Anglia. Ph.D. thesis, University of East Anglia.
6. Tyler, A., Harper, P. S., Walker, D. A., Davies, K. and New-
combe, R. G. (1982) Journal of the Biosocial Sciences, 14, 379.
7. Walker, D. A., Harper, P. S., Newcombe, R. G. and Davies, K.
(1983) Journal of Medical Genetics, 20, 12.
8. Reed, T. E. and Neel, J. V. (1959) American Journal of Human
Genetics, 11, 107.
9. Tyler, A. and Harper, P. S. (1983) Journal of Medical Genetics, 20,
179.
10. Newcombe, R. G. (1981) Annals of Human Genetics, 45, 375.
11. Newcombe, R. G., Walker, D. A. and Harper, P. S. (1981) ibid.,
p.387.
12. Harper, P. S., Tyler, A., Smith, S., Jones, P., Newcombe, R. G.
and McBroom, V. (1982) Journal of Medical Genetics, 19, 241.
13. Carter, C. O. and Evans, K. (1979) Lancet, 2, 470.
14. Harper, P. S., Walker, D. A., Tyler, A., Newcombe, R. G. and
Davies, K. (1979) Lancet, 2, 346.
15. Harper, P. S., Tyler, A., Smith, S., Jones, P., Newcombe, R. G.
and McBroom, V. (1981) Lancet, 2, 411.
16. Brackenridge, C. J., Case, J., Chiu, E., Propert, D. N., Teltscher,
B. and Wallace, D. C. (1978) Annals of Human Genetics, 42, 203.
17. Pericak-Vance, M. A., Conneally, P. M., Merrit, A. D. et al.
(1979) Advances in Neurology, 23, 59.
18. Volkers, W. S., Went, L. N., Vegter-Van Der Vlis, M., Harper,
P. S. and Caro, A. (1980) Annals of Human Genetics, 44, 75.
19. Gusella, I. F., Wexler, N. S., Conneally, P. M. et al. (1983) Nature,
306, 244.
20. Harper, P. S., Youngman, S., Anderson, M. A. et al. (1985) Journal
of Medical Genetics, in press.
21. Youngman, S., Sarfarazi, M., Quarrell, O. and Harper, P. S.
(1985) unpublished data.
22. Gusella, J. F., Tanzi, R. E., Anderson, M. E. et al. (1984) Science,
225, 1320.
23. Harper, P. S. and Sarfarazi, M. (1985) British Medical Journal, 290,
129.
24. Rodeck, C. H. and Morsman, J. M. (1983) British Medical Bulletin,
39, 338.
25. Upadhyaya, M. Harper, P. S., Williams, H. and Roberts, A.
(1985) In First Trimester Fetal Diagnosis, pp. 286-94. (ed M. Fraccaro,
G. Simoni and B. Brambati.) Berlin: Springer.
Journal of the Royal College of Physicians of London Vol. 20 No. 1 January 1986
|
PMC005xxxxxx/PMC5371139.txt | Adjusting Follow-up Intervals in a Diabetic
Clinic: Implications for Costs and Quality of
Care
RAYMOND B. JONES, MSc,* Research Associate, Department of Community Health,
University Hospital, Nottingham
ANTHONY J. HEDLEX FRCPEd, Professor of Public Health, Department of Community
Medicine, University of Glasgow, Ruchill Hospital, Glasgow
It is obvious that follow-up interval is one of the main
determinants of the cost of out-patient care for chronic
disease. It is also obvious that to lengthen follow-up
intervals will create 'free time' in an out-patient clinic, so
that either the number of sessions can be cut or more
patients who are not at present attending an out-patient
clinic can be given appointments. What is not known is
how critical is the follow-up interval to the outcome of
care, and by what degree follow-up intervals would have
to be lengthened to create a given number of 'free'
appointments. Indeed, many clinicians running out-
patient clinics for diabetics do not even know how many
patients attend their clinic.
Hillfl] and Day[2] have given guidelines on the organi-
sation of care for diabetics and a number of alternative
systems of care are in operation[3-5]. For example, in
Poole[4] general practitioners care for nearly all well-
controlled uncomplicated maturity onset diabetics and
some insulin-treated diabetics with good control. The
return of many patients to the routine care of GPs allowed
one of the two weekly diabetic clinics to be devoted
entirely to the screening for and follow-up of diabetic
retinopathy. Home and Walford[6] emphasised the role
of the specialist clinic in collaboration with general prac-
tice. However, Hurwitz et al. [7] pointed out that prob-
ably only 50 per cent of known diabetics in a health
district have the support of a diabetic clinic, and many
consultants consider that their clinics are full and cannot
make further contributions without additional resources.
While overall assessments have been made of shared care
schemes, little investigation has been made of the cost-
effectiveness of methods used to run out-patient clinics.
The diabetic clinics at University Hospital, Notting-
ham, are supported by a register and information sys-
tem[8], which allows a wide range of clinical information
to be collected and summarised in standard medical
records and it uses an integral appointments system in the
management of the clinic. The medical record includes a
problem list, comprising a complete summary of both
active and inactive medical, social and psychological
problems. This is constructed from information collected
during the consultation using a checklist of diabetes
related problems and free text entry for other problems.
This article describes how a computer-based register can
be used (a) to investigate how closely current follow-up
intervals meet the observed clinical characteristics of
patients; (b) to estimate by how much follow-up intervals
need to be lengthened to allow regular examination of
diabetics currently not attending, and (c) to monitor the
effects of changes in follow-up interval on clinical out-
comes. None of these three actions is possible without
such a system.
Patients and Methods
Clinics
The diabetic clinic under study is held twice weekly and
in 1983 a total of 4,860 attendances was made by 2,226
patients, of whom 54 per cent were male and 46 per cent
female, 59 per cent were insulin-treated, 27 per cent
tablet-treated and 14 per cent treated by diet alone. The
mean age was 51 years and the mean duration of diabetes
12 years.
'Follow-up interval' was defined as the period in
months from the last attendance to the next booked
appointment. Clinical information in the computer-held
medical records[8] has been analysed, to identify import-
ant determinants of high or low frequency of attendance,
by cross-tabulations of various characteristics against
follow-up interval and by a stepwise multiple logistic
regression analysis using the statistical package GLIM
(Release 3)[9]. For the cross-tabulations the follow-up
interval, in periods of four months, was compared against
age in 20 year bands, sex, duration of diabetes (10-year
groups), treatment type (insulin or non-insulin treated),
total glycosylated haemoglobin (Hbal) (steps of 5 per
cent), retinopathy (any or none), neuropathy (any or
none), number of problems on problem list and doctor
"Correspondence to: R. B. Jones, Esq., Lecturer in Medical Infor-
mation Science, Department of Community Medicine, Ruchill Hospi-
tal, Glasgow G20 9NB.
36 Journal of the Royal College of Physicians of London Vol. 20 No. 1 January 1986
seen. In the multiple logistic regression analysis the
characteristics of patients with follow-up intervals of less
than 6 months and of 6 months or more were compared.
The independent variables were added and subtracted
from the model until a 'best' model was found to which
no other variable made a significant contribution. The
independent variables included age, any retinopathy,
new vessels, Hbal, duration of diabetes, any neuropathy,
number of problems, and doctor seen. The analysis was
performed after the population had been partitioned by
sex and type of treatment.
Choice of Follow-up Intervals
An experiment was conducted to examine the level of
agreement between clinicians in their choice of follow-up
intervals for different patients, and to identify those
clinical characteristics which were the principal determi-
nants of the length of the interval.
Six patients were chosen at random from the list of
attenders for each of five clinicians (three consultants, two
registrars). The clinicians were presented with computer-
produced summaries with identification details deleted
and copies of the most recent consultation records. A
balanced incomplete block design[10] was used to allocate
patients' records to doctors. In addition each doctor was
asked to estimate the optimal follow-up interval for 12
patients of other doctors. These were combined with the
intervals allocated for the six patients seen in the clinic, so
that follow-up intervals were available for 18 patients.
The combined results were presented and the doctors
asked to justify the intervals they prescribed. The differ-
ence between intervals allocated in the clinic and those
estimated in the experiment were investigated for each
doctor, using a Mann-Whitney U-test on the difference
between his estimations and the mean of other esti-
mations for each patient.
Estimation of Resource Use
The effect of variation in follow-up intervals on the use of
resources in the clinic was studied. The diabetic clinics
under study operate on fifteen minute appointments and
in total there are approximately 60,000 doctor/patient
consultation minutes per year. Base-line figures were
used to estimate the effects of increases in follow-up
intervals in terms of either additional consultations avail-
able or increases in the mean duration of an individual
consultation. These estimates were combined with cur-
rent costs to determine the revenue consequences for out-
patient services and costs to patients. Some costs are fixed
according to clinic time, including costs of clinic recep-
tionists, doctors' time per session and nursing staff. Some
costs are dependent on booked appointments; these in-
clude clinic preparation costs, blood and urine tests and
patient travelling and time. Other costs are partly fixed,
being dependent on the number of attendances and on the
clinic population size. For example, the work of the
records clerks and secretaries will be more per attendance
for a patient who attends relatively infrequently than for a
frequent attender, mainly because of the work in setting
up new documents for new referrals. In addition, there is
also a workload associated with running a clinic, for
example, preparation of clinic lists, regardless of the
number of attenders. On the basis of an activity analysis
of personnel it has been assumed that the costs of records
clerks, secretaries, doctors' clinic time not related to
patient contact, postage and stationery are approximately
divided as 40 per cent fixed, 40 per cent per attendance
and 20 per cent per patient in the clinic population. The
doctors' time outside patient contact was estimated as
equal to consultation time to allow for activities such as
students and junior doctors 'sitting-in' on the consul-
tation, and dictation of letters. For costing purposes it has
been assumed that the total time spent on a visit to the
clinic by each patient remains the same even if the
consultation increases from 15 to 19.5 minutes and that if
further patients are recruited to the clinic their travelling
and time costs are the same as those of the current
attenders. Salary costs have been calculated using mid-
points of the relevant salary scales. (Details of costings are
available from the authors.)
Results
Follow-up Intervals
Figure 1 shows the percentage of clinic attenders with
given follow-up intervals for a typical month (May 1983).
The mean interval was 5.8 months but there is a strong
'digit preference' for 6 and 12 months.
Cross-tabulations showed that shorter follow-up inter-
vals were associated with young insulin-treated diabetics,
poor control and retinopathy, but not with maturity onset
diabetes, total number of problems on the problem list, or
neuropathy. The length of follow-up interval was strongly
associated with the doctor seen.
Table 1 summarises results from the multiple logistic
regression analysis for follow-up intervals of less than 6
Follow-up interval (months)
Fig. 1. Follow-up intervals of diabetics attending an out-
patient clinic.
Journal of the Royal College of Physicians of London Vol. 20 No. 1 January 1986 37
Table 1. 'Best' models from multiple logistic regression analysis
showing significance of predictors and variation explained by
each model. Doctor?doctor prescribing follow-up interval;
Hbal?last recorded haemoglobin Al; retin?presence of any
retinopathy.
Clinical characteristics with high predictive value
Predicted Insulin treated Non-insulin treated
variable M F M F
Follow-up Doctor** Doctor** Doctor** Doctor
interval Age** Hbal** Hbal** Hbal**
<6 months retin*
Variation 16% 10% 10% 10%
explained
*/><0.05; **P<0.001
* *
months. The doctor seen and Hbal are the most consist-
ent predictors of follow-up intervals. However, the per-
centage of the variation explained by the models never
exceeds 16 per cent.
Clinical Decision-Making
The estimation of follow-up intervals in the experiment
using medical records showed a significant difference
(F = 17.5; 4 and 56 df; PcO.Ol) between doctors. For one
doctor in particular, intervals allocated in the clinic were
much shorter (U = 6; SD(U) = 10.7; P< 0.005) than those
allocated 'blind' using patient records alone. The vari-
ation in intervals allocated for individual patients was
considerable; for example, three weeks when seen in the
clinic and three and four months when using the medical
record only. During the course of the discussion of the
preliminary results, doctors revised their estimates in the
light of information not available from the computer
record or photocopied notes, such as missing entries from
the problem list. There were no significant differences
between clinicians for the revised estimates. In their
judgement an increase in the prescribed follow-up inter-
vals, for example from six to nine months, would be
acceptable.
Effects of Changes in Follow-up Intervals
Table 2 shows the number of free appointments of 15
minutes' length which would be created or, alternatively,
the increased duration of a consultation produced by
incremental increases in follow-up intervals. An increase
Table 2. Effects of increases in follow-up intervals on clinic
resources.
Follow-up interval Additional Mean duration of
Increase(%) Months 15-minute consultations
appointments (min)
Current 6.7 0 15.0
position
+ 10 7.3 443 16.8
+ 20 8.0 666 18.0
+ 30 8.7 928 19.5
+ 40 9.4 1148 21.0
+ 50 10.0 1339 22.5
of 30 per cent, which, for example, would mean increas-
ing an interval of six months to almost eight months,
would free just under 1,000 fifteen-minute appointments.
Table 3 presents the costs, in terms of patients' travel-
ling time, medical and nursing staff costs and adminis-
trative costs of attendance, for three options: (a) a clinic
population of 2,226 attenders and a mean follow-up
interval of 6.7 months; (b) an increase in all intervals by
30 per cent so that these 2,226 attenders had fewer but
longer consultations per year; (c) an increase in follow-up
intervals for current attenders with consultations remain-
ing at 15 minutes each, and the recruitment of a further
1,856 diabetics in need of follow-up, each having one
consultation every two years. The increase in the total
annual costs of running the clinic for this option is less
than 5 per cent.
Discussion
The implementation of appropriate clinical information
systems allows the examination of the effects of clinical
decisions on the use of resources in out-patient depart-
ments. In particular, areas in which resources can be
reallocated can be identified, as the need to support new
therapeutic advances or patient management schemes
will predictably arise. This potential use of computer
systems should be taken into account when considering
the costs and benefits of implementation.
Clinical decision-making in the choice of follow-up
intervals for different patients is often based on factors
such as poor control which common-sense suggests should
lead to more frequent follow-up. However, personal
preferences play an important role; the 'doctor seen' is a 7
strong predictor of the follow-up interval and there is a
marked preference for six and 12 months. When
Table 3. Total patient costs per year and cost per patient per year for alternative options with increased length of follow-up. F?fixed
costs; A?cost per attendance; P?cost per patient per year.
Increase in follow-up Annual cost per
interval(%) Option Annual total cost equation Annual total cost(?) patient(?)
0 Current option F + 3987A + 2226P 95156 43
30 Increased length of
consultation F + 3070A + 2226P 80392 36
30 Increased number of attenders F + 3987A + 4082P 98887 24
38 Journal of the Royal College of Physicians of London Vol. 20 No. 1 January 1986
information from the medical records was used as the
basis for decision-making there was considerable vari-
ation in the choice of follow-up intervals. This was largely
eliminated by a group discussion of each patient's needs
and criteria for follow-up.
There are clear arguments for the development of
protocols of carefll] based on consensus about the cri-
teria for follow-up of patients who need continuing
surveillance. They would provide a better framework for
continuing evaluation, through routine patient contacts,
of the effect of the duration of follow-up intervals on the
long-term outcome of medical care. Equally important is
the need for an assessment of the role of the diabetic clinic
in the provision of care to diabetics within a health
district.
Few clinics have been able to adopt a population
approach to the provision of services, mainly because of
organisational problems and the apparent demand for
scarce out-patient clinic resources that this creates. Var-
ious studies[7] suggest that 45-54 per cent of diabetics do
not currently attend any out-patient clinic for their
diabetes; few of these are likely to have had a fundal
examination within the last two years. Our own experi-
ence suggests that few GPs feel confident of performing a
fundal examination, but, by lengthening the follow-up
intervals of patients already attending the clinic, screen-
ing for diabetic retinopathy for the complete population at
risk could be achieved with existing resources. The long-
term benefits and savings of this change in resource use
are considerable. On the other hand, out-patient clinics
provide an expensive form of care. For example, in a
comparison of the follow-up of patients with thyroid
disease[12], the estimated cost of a visit to the GP was less
than 50 per cent of an out-patient attendance. Travel and
time costs incurred by the patients may create hardship
and we believe they are sometimes an important factor in
instances where clinic follow-up is discontinued. The
ways in which patients are now referred to and retained
by diabetic clinics sometimes indicate the lack of a
coherent role for the clinic in diabetic care.
More work needs to be done on devising protocols of
care for diabetes which provide guidelines on the frequen-
cy and most appropriate place for follow-up examina-
tions. This will in turn demand good quality data that can
be used to measure the cost and outcome of different
policies for adjusting the balance of care between hospital
and general practice.
Summary
One of the main determinants of cost in the follow-up of
patients with chronic disease is the frequency with which
they are seen in out-patient clinics. The implementation
of clinical information systems allows this relationship to
be investigated and rationalised. Such potential uses of
clinical information systems should be considered when
evaluating the costs and benefits of implementation.
In 2,226 diabetic clinic attenders, of ten variables
studied, the doctor seen was one of the most consistent
significant predictors (P< 0.001) of follow-up intervals
and many patients were seen more often than was
probably necessary. An increase of 30 per cent in all
follow-up intervals would be clinically acceptable and
would allow nearly 2,000 known non-attenders to be
given a biannual examination. The increase in total
annual costs would probably be less than 5 per cent.
Acknowledgments
We would like to thank Dr S. P. Allison, Dr D. J.
Hosking, and Dr R. B. Tattersall for their permission to
use data on their patients, Dr S. Heller and Dr M.
Bastow for their collaboration and Dr J. Pearson for
statistical advice. We are particularly grateful to Barbara
Pollard and Freda Giles for their skilled work on the
diabetic register. Mr R. B.Jones was supported by grants
from Nordisk UK Ltd and the National Medical Re-
search Fund.
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11. McDonald, C.J. (1976) New England Journal of Medicine, 295, 1351.
12. Jones, S.J., Hedley, A. J., Curtis, B. et al. (1982) Lancet, 1, 1229.
Journal of the Royal College of Physicians of London Vol. 20 No. 1 January 1986 39
|
PMC005xxxxxx/PMC5371140.txt | Bleeding Oesophageal Varices:
Referral Bias and Survival
D. W. BULLIMORE, md, mrcp(uk)
Lecturer in Medicine, Department of Medicine, St James's Hospital, Leeds
In the UK, follow-up studies on subjects with varices and
gastrointestinal bleeding are generally from national or
regional referral centres. These studies are frequently said
to be biased by the inclusion of 'good risk' patients
referred from surrounding hospitals[l]. Such patients are
believed to have a better prognosis by virtue of the fact
that they have survived the initial bleed for sufficiently
long to be stabilised and transferred. This, in a condition
with a high early mortality, will result in a privileged
group of patients with an improved survival when com-
pared to a group of subjects admitted direct to a hospital
from its local catchment area. Thus, if this degree of bias
is significant, results and conclusions drawn from such
studies will be of limited value in deciding management
policies and assessing results in smaller units. This study
assesses to what extent selection bias exists in a regional
referral centre. It therefore concentrates on those subjects
referred direct to one unit from the immediate catchment
area of the hospital and those subjects referred from other
hospitals in the vicinity to that unit.
Patients, Definitions and Methods
All subjects diagnosed as having oesophageal varices in
one endoscopy unit between 1973 and 1982 and suffering
their first admission to this hospital with gastrointestinal
haemorrhage were eligible; 143 such patients were identi-
fied.
Patients were subdivided according to source of refer-
ral: direct (direct admission to the gastroenterology unit);
internal (referral to endoscopy unit from another physi-
cian without necessarily transfer of care); in-patient exter-
nal (transfer from another hospital within a radius of up
to 70 miles); and out-patient external (original referral for
further assessment by another hospital as an out-patient).
The diagnosis made during the admission or on subse-
quent follow-up and based on a combination of clinical,
biochemical and pathological criteria was accepted in
classifying patients.
The source of bleeding was determined endoscopically.
It was considered as undefined if there was more than one
potential site with no clear evidence as to which site had
bled. The diagnosis of variceal bleeding was confirmed if
there was active bleeding from a varix, adherent clot over
a varix, or no other potential site[2].
Functional hepatic reserve was assessed by giving the
patient a modified Child's grade on admission[3j.
Patients with extrahepatic obstruction were assigned a
Child's grade using the same criteria. Data were available
to calculate a Child's grade on admission in 111-of the 117
admissions in the direct and external groups (95 per cent).
Death was attributed to one of the following causes:
hepatic failure, haemorrhage, hepato-renal failure, infec-
tion, and other (or indeterminate)[4].
In the statistical analysis, subgroup survival was com-
pared using life-table analysis and the log-rank test[5].
Fisher's test and ridit analysis[6] were used to compare
differences between subgroups.
Results
Twenty-six of the 143 subjects were internal referrals.
The remainder consisted of 37 direct referrals and 80
external referrals (63 in-patient external and 17 out-
patient external). The clinical details of the whole group
and the direct and external subgroups are given in Table
1. The direct and external subgroups were similar in
Table 1. Clinical characteristics of varices subjects. (P values
for direct vs. external group.)
All subjects Direct External
Number 143 37 80
Male:Female 1.13:1 1.46:1 1.11:1 N.S.
Mean age (years) 52.3 52.4 48.5 /5=0.05
% over 60 35 33 25 N.S.
% Previous bleed 40 30 50 P< 0.05
% Alcoholic cirrhosis 29 32 27 N.S.
% Extrahepatic block 12 19 12 N.S.
% Child's A 29 31 30 N.S.
% Child's B 35 37 36 N.S.
% Child's C 36 31 34 N.S.
% Ascites present 38 32 38 N.S.
% Encephalopathic 29 30 27 N.S.
many respects. There was the same distribution of func-
tional hepatic reserve as judged by the Child's grade and
the same proportion with ascites and with encephalopathy
in each subgroup. The proportion with alcoholic cirrhosis
and with extrahepatic block was again similar between
subgroups. The mean age of the external group was four
years less (P=0.05) but the proportion over 60 was not
significantly increased. The proportion with a previous
Journal of the Royal College of Physicians of London Vol. 19 No. 3 July 1985 189
Table 2. Clinical course of varices subjects. (P values for direct
vs. external group.)
All
Subjects Direct External
Number 143 37 80
Mean units transfused for
those requiring blood 13.7 11.5 15.3 P<0.002
Mean units transfused for
whole group 10.3 7.3 12.4 P<0.001
% Variceal source 71 67 82 N.S.
% Tamponade 31 22 36 N.S.
% Vasopressin 19 5 25 /5<0.05
% Surgical referral 29 35 34 N.S.
gastrointestinal bleed was greater in the external group
but high in both groups (jP<0.05).
Table 2 gives details of the patients' hospital courses.
Compared with the direct group the external group had
higher transfusion requirements (blood and packed cells)
both on the basis of units transfused/subject and units
transfused/subject requiring transfusion. The source of
bleeding was variceal in 67 per cent of the direct group
and in 82 per cent of the external group, an insignificant
difference. Cases in which the source of bleeding had
been classified as undefined were not included as being
variceal.
Of 32 deaths in the external and direct groups 17 (53
per cent) were due to haemorrhage, 9 (28 per cent) died of
hepatic failure and 5 (16 per cent) from hepato-renal
failure. One death was from an unrelated cause.
Survival to discharge was 70 per cent in the direct and
74 per cent in the external group (no significant differ-
ence). Survival in those bleeding from varices was 72 per
cent in both groups. Survival was strongly dependent on
Child's grade (A = 94 per cent, B = 80 per cent, C = 46
per cent). Fig. 1 compares survival in the direct and
external groups using life-table analysis and shows it to be
the same in both groups (P>0.1, chi square = 0.037).
Survival in those over 60 compared with those under 60
was less good (P<0.01, chi square = 7.57).
Of the external referrals 62.5 per cent were from
hospitals within a 15 mile radius and 79 per cent were
from within 30 miles. All but one patient came from
within 70 miles.
In the externally referred group 56 per cent were
transferred on the day of admission or the following day
and 77 per cent were transferred within one week.
Comparing subjects transferred at two or more days and
those transferred earlier, there was no difference in
survival (P^O.l, chi square = 0.6); 2.5 per cent of sub-
jects died within one day and 7 per cent within one week.
Over the ten-year study some changes were noted in
patient referral patterns. Comparing the first five-year
period (1973-77) with the second (1978-82), referrals
increased ? 62 per cent were in the second period ? the
proportion of external referrals rose from 43 per cent to
62 per cent (/J<0.05), the proportion of alcoholics rose
from 24 per cent to 31 per cent (jP>0.1), as judged by
Child's grade, the patients had on average less severe
disease (Child's A rose from 14 per cent to 37.5 per cent
(P< 0.005), Child's B fell from 44 per cent to 29.5 per
Fig. 1. Life table analysis of external ( ) and direct ( ) groups from hospital admission. Percentage standard error
(% SE) is for the combined groups. Population under observation in each group with time is as indicated. Note discontinuity in
axis. P^> 0.1, chi square = 0. 037.
Days
190 Journal of the Royal College of Physicians of London Vol. 19 No. 3 July 1985
cent (P = 0.06), and Child's C fell from 42 per cent to 33
per cent (P>0.1)). This change in distribution of Child's
grade applied to both local and referred groups.
Discussion
This study investigates the degree of 'bias' resulting from
the inclusion of externally referred patients in a study
assessing prognosis of subjects with oesophageal varices
and gastrointestinal bleeding. Such bias might exist either
because of selection of patients by their ability to survive
an initial bleeding episode for sufficiently long to be
stabilised and transferred or because of selection on
clinical grounds. For instance, there could be a tendency
not to refer a particular group of subjects, e.g. the Child's
* C subject or the alcoholic. The similarity of the clinical
features of the two groups suggests that this is not the case
(Table 1). Two differences were present. First, more
subjects in the external group had experienced a previous
gastrointestinal bleed. This is to be expected, as if a local
subject experienced a gastrointestinal bleed he would be
more likely to be admitted to this hospital and meet the
criteria for inclusion in the study at that point. There was
no difference in survival to discharge in subjects with and
without previous gastrointestinal bleeding when adjusted
for Child's grade. Second, the mean age of the external
group was four years less. However, the proportion over
60, for whom survival is less good, was similar.
While the clinical features were remarkably similar, the
course of the patients differed in some respects ? notably
in a greater transfusion requirement (blood and packed
cells) in the external group (Table 2). There was also a
greater use of vasopressin but not of balloon tamponade.
These differences were not reflected in the clinical out-
come.
The similarity in survival both in the short term (72 per
cent) and the long term (Fig. 1, P>0.1, chi
square = 0.037) is in line with the similar clinical features
of the two groups. It demonstrates that no significant bias
in terms of overall survival exists due to the inclusion of
externally referred cases along with the directly referred
cases.
The reasons for this are apparent when the geographi-
cal distribution and timing of transfer are considered.
Seventy-nine per cent of the subjects were referred from
within 30 miles, a proportion which is probably very
similar to many regional referral units. Therefore the
period of stabilisation required to allow transfer is brief;
56 per cent were transferred on the day of admission or
the following day and 77 per cent within one week. Early
deaths were uncommon ? only 7 per cent of subjects died
within one week (25 per cent of deaths). In contrast,
Graham and Smith[2] drew attention to the high early
'* mortality of variceal bleeding, 76 per cent of deaths
occurring within one week of the index bleed; 70 per cent
of their subjects were Child's C and 91 per cent were
alcoholics, figures representative of many series from the
USA. They emphasised that survival in studies on such
patients will closely depend on what is defined as the zero
time for admission to the study. However, while it is
desirable to include subjects from the time they sustain a
haemorrhage, as in this study, delays of one or two days
would appear to alter survival curves far less in the case of
a population of subjects from the UK than from the USA.
It is also evident that the demonstration of a significant
reduction in mortality by some technique (e.g. variceal
sclerosis) in a population with a hospital discharge sur-
vival of 33 per cent[7] does not imply that a similar, or
indeed any, reduction in mortality will occur in a popu-
lation with a discharge survival of 72 per cent. Tech-
niques have to be assessed in populations reasonably
similar to those in which they are to be applied. In
assessing whether the results of a study can be applied to
another population the criteria used should be similar to
those used in judging whether the control and test groups
in the study were clinically similar, i.e. distribution of
Child's grade and other features.
Series from regional referral centres can provide useful
information to assist patient management in District
General Hospitals, as the patient populations will be
more alike than patient populations in studies from
abroad and possibly than those from national referral
centres.
Summary
The survival of subjects with varices and gastrointestinal
bleeding transferred to a referral centre from outside
hospitals was compared with the survival of those ad-
mitted directly. The clinical features of the two groups
were very similar and survival was 72 per cent. This
suggests that the bias introduced by including such
external referrals in series from regional centres studying
survival in these patients is small and that they provide
information relevant to patient management in smaller
units. Of the referrals 79 per cent were from within 30
miles, transfer occurred rapidly and early mortality was
low (7 per cent by one week). These factors help to
minimise bias.
References
1. Silk, D. B. A. and Williams, R. (1979) In Liver and biliary disease,
p. 1002. (ed R. Wright, K. G. M. M. Alberti, S. Karran and G. H.
Millward-Sadler.) London: Saunders.
2. Graham, D. Y. and Smith, J. L. (1981) Gastroenterology, 80, 800.
3. Pugh, R. N. H., Murray-Lyon, I. M., Dawson, J. L., Pietroni, M.
C. and Williams, R. (1973) British Journal of Surgery, 60, 646.
4. Garceau, A. J. and Chalmers, T. C. (1963) New England Journal of
Medicine, 268, 469.
5. Peto, R., Pike, M. C., Armitage, P. et al. (1977) British Journal of
Cancer, 35, 1.
6. Fleiss, J. L. (1973) In Statistical methods for rates and proportions, p.92.
Chichester: John Wiley.
7. Soehendra, N., de Heer, K. and Kempeneers, I. (1983) In Clinical
hepatology, p.281. (ed G. Csomos and H. Thaler.) Berlin, Heidel-
berg: Springer Verlag.
Journal of the Royal College of Physicians of London Vol. 19 No. 3 July 1985
|
PMC005xxxxxx/PMC5371141.txt | Food Allergy, Hypersensitivity and Intolerance
DAVID J. PEARSON, mb, PhD, mrcp(UK)
Senior Lecturer in Medicine, University of Manchester
Most of the basic clinical features of food allergic states
were established by the 1920s. Unfortunately the subject
then became bedevilled by extravagant and fanciful
claims. As a result, in the UK at least, it languished under
an air of quackery for nearly 50 years. It is even more
unfortunate that a renewal of interest in the objective
study of very real phenomena has been associated with
the resurrection of wild unsubstantiated claims of the
importance of food allergy in all sorts of conditions in
addition to the classical atopic diseases of asthma, eczema,
urticaria and gastrointestinal food hypersensitivity.
As May[l] pointed out many misunderstandings about
food allergy have arisen because of a failure to appreciate
the power of the placebo effect and to take steps to
overcome this and the results of observer bias. Also, with
modern developments in biochemistry and immunology,
it has become clear that a number of different mecha-
nisms can be responsible for syndromes that are superfi-
cially identical.
Classification of Adverse Reactions to Food
Adverse reactions to food can be classified both by
aetiological mechanism (Fig. 1) and according to the
observed symptom pattern. Non-immunological allergo-
mimetic responses have been described as pseudo-allergic
reactions (PAR)[2]. Those which resemble IgE-mediated
disease can be considered anaphylactoid.
It is becoming increasingly clear that the most common
reason for failing to tolerate specific foods is psychologi-
cal. Therefore the word intolerance should be allowed to t
revert to its meaning in simple English, namely, any
inability to put up with something without ill-effect. Since ?
hypersensitivity was used to describe unusual adverse
reactions long before an immunological aetiology was
established for any, I suggest it be applied to all unexpect- i
ed adverse reactions and be defined as: 'An organic host-
damaging reaction which is qualitatively different from,
or quantitatively greater than, the effects which the same
dose of that substance would have on the generality of the
population'.
Food allergy is hypersensitivity in which there is evi-
dence of an immunological aetiology. To date, IgE- /
mediated reactions in atopy are the only immunological
responses to food whose role in the generation of human
disease has been demonstrated convincingly, although
other allergic processes do seem probable (e.g. in eczema,
coeliac disease).
Fig. 1. Aetiological classification of adverse food reactions.
ADVERSE REACTIONS TO FOOD
I i
USUAL UNUSUAL
eg. toxins, pharmacologic agents intolerance of.
generally non-toxic substances
ORGANIC
(HYPERSENSITIVITY)
PSYCHOGENIC
I
ALLERGIC
(Immunologic)
J
Distaste
I
Phobias
Pseudo-food allergy
syndrome
IDIOSYNCRATIC
(Non-immunologic)
r
IgE. mediated
(reaginic)
Non-reaginic
(unproven)
Metabolic
(eg. Alactasia)
Pharmacologic
(eg. ASA-sensitivity)
Munchausen's
syndrome'
IDIOPATHIC
Autonomic
(eg. S02)
154 Journal of the Royal College of Physicians of London Vol. 19 No. 3 July 1985
Cultural background has major influences on what is
considered desirable and probably most people avoid
some foods which are relished by others. Sometimes the
exaggeration of simple distaste into food fads and pho-
bias, or the food avoidance of anorexia nervosa, may be
justified as being due to an 'allergy'. However, such
patients tend not to present their food avoidance for
medical treatment and if seen, rarely present diagnostic
problems. Adult Munchausen's syndrome patients who
simulate or deliberately generate genuine anaphylactic
emergencies in themselves are rare but well recog-
nised[3]. The allergic form of Meadow's syndrome
(Munchausen's-by-proxy) is also described[4].
In practice, for those wishing to treat or investigate
food-allergic disease, the two most important problems
are the psychological processes that can bring about
pathophysiological changes identical to those of genuine
immunological reactions; this is what we have called
'pseudo-food allergy' (PFA). The latter is characterised
by the patients' false conviction that they suffer from food
allergy, to which they may attribute symptoms quite
dissimilar from those of classical allergic disorders.
Psychologically-Induced Allergomimetic Changes
Relationships between physiological changes, neural and
hormonal reflexes, biochemical abnormalities, immuno-
logical processes, and mental function are probably more
complex in atopic diseases than in any other group of
human disorders. Allergy can lead to organic brain
syndromes, directly through hypoxaemia or hypotension
or indirectly through the common CNS adverse effects of
many anti-allergic drugs[5,6]. The distress associated
with the physical effects of disease can lead to anxiety and
depressive reactions. Chronic or recurrent problems in
childhood, particularly disfiguring conditions such as
eczema and physical restrictions due to asthma, have
long-term effects on the development of personality,
social skills, and choice of work and leisure activities.
Conversely, psychological events can also produce many
of the physiological changes which follow allergic reac-
tions. On occasion these somatopsychic and psychoso-
matic influences appear to lead to a vicious circle of self-
perpetuating illness.
Both human[7-13] and animal experiments[14,15] in-
dicate the capacity of neural and psychological events to
produce allergomimetic physical changes in the lung,
nose, skin and gastrointestinal tract. Some may involve
neurological modulation of mast cell mediator release.
These psychogenic changes are due to one of two possible
mechanisms: (1) imbalanced end-organ responsiveness to
the normal autonomic nervous system activation of
emotional arousal; or (2) specific responses resulting from
suggestion or conditioned reflexes.
It must be emphasised that the processes under discus-
sion do not require any psychological abnormality for
their generation. Failure to recognise this, and confusion
of psychoanalytical with psychophysiological concepts of
psychosomatic causation are responsible for the neglect of
much important early work. Although psychogenic symp-
tom exacerbations are common, comparative studies
show no significant increase in the frequency of psychi-
atric disorder in atopic patients with mild or moderate
disease[16,17]. The slightly increased frequency in the
most severely affected individuals is entirely compatible
with its being secondary, and is of the same order as that
seen in other patients with similar degrees of physical
handicap[16-19]. Of course, in atopic patients who inde-
pendently develop a psychiatric illness, physical function
may reflect the mental state through the same processes
that operate in the non-psychiatric case.
Abnormal responsiveness to chemical transmitters is
one of the hallmarks of atopic disease. In the lung this is
characterised by bronchial hyper-reactivity. However,
the basic abnormality is systemic. In vivo gluconeogenic,
cardiovascular ant! cAMP responses to exogenous /3-
adrenergic agents are decreased in atopic groups[20-22].
Unusual dermal responses to cholinergic agonists in
eczema were one of the earliest physiological peculiarities
ever described in atopy[23]. The generation of these
abnormalities is the subject of a number of hypotheses,
but these are immaterial to the present discussion. It is an
empirical observation that atopic individuals behave as if
they have an unbalanced autonomic system in which
parasympathetic and a-adrenergic actions predominate
over the normally counterbalancing effects of /3-adrener-
gic activity[22] (Fig. 2).
The results of this autonomic imbalance vary between
tissues, depending on their innervation and distribution
of receptors. In the lung it leads to bronchospastic
responses to stimuli producing efferent vagal or sympa-
thetic activity, including local reflexes and generalised
responses such as those to exercise and the intense
emotions of anger and fear which have been recognised as
significant inducers of asthma since Hippocrates' time. It
is probable that every asthmatic will experience some
degree of bronchoconstriction if stressed intensely
enough. As any examination candidate will attest, gastro-
intestinal motility changes are a common response to
fear, but it is not known whether these are any different in
atopics. However, functional bladder outlet obstruction
may be more frequent in patients with allergic problems.
Studies attempting to assess the relative importance of
psychological, allergic and infective processes have con-
cluded that all are involved at some time in most asthma-
tics[24,25]. Some psychogenic attacks have
characteristics suggesting conditioned responses[26-28].
The literature records many cases who have developed
asthma, rhinitis, itching or skin lesions when exposed to
artificial flowers, or when shown pictures of allergens.
Sometimes these responses may initially be due to simple
anxiety associated, with circumstances that have pre-
viously induced severe allergic reactions (e.g. anaphylaxis
related to a particular food). Such reactions are clearly
self-reinforcing. However, animal experiments show that
conditioned asthma can occur without the biochemical
abnormalities that characterise human atopy[14,15]. At-
ropine inhibition of psychogenic asthma in both humans
and animals suggests that it is vagally mediated
[9,11,12,15],
Experimental observations imply that suggestion can
induce physical changes without necessarily requiring
Journal of the Royal College of Physicians of London Vol. 19 No. 3 July 1985
155
previous conditioning[8-13], However, clinically and in
most experiments purporting to demonstrate the role of
suggestion in humans, it is virtually impossible to dissect
the effects of simple suggestion, conditioned reflexes and
anxiety. The crucial point is that about half of all
asthmatics will produce measurable bronchoconstriction
if they falsely believe they have received an allergen or
pulmonary irritant. Skin lesions can be produced in 20
per cent of patients with urticaria purely by discussing
events associated with previous attacks[7]. The classical
studies of Graham, Wolf and Wolff[7] demonstrated that
a wide range of other changes, including local eosinophi-
lia, nausea and abdominal pain associated with measur-
able changes in duodenal motility or diarrhoea, can also
be induced by telling patients they have been given a food
to which they believe themselves allergic.
It is clear that any objective investigation of hypersensi-
tivity must take account of the possibility of psychogenic
changes. Even physiological measurements associated
with histological changes or evidence of inflammatory
mediator release do not prove the nature of the initiating
event, although they may indicate common final path-
ways. There is no form of blood or skin test which
accurately predicts the response to ingestion. We are left
with double-blind administration as the only absolute
proof of the organic basis of any triggering event, but also
with the question of how such tests should be performed
and interpreted.
Double-blind Provocation Tests
Several techniques of food administration have been used
for double-blind tests. Nasogastric intubation is uncom-
fortable for the patient and it can be difficult to hide the
nature of the injected substance from the administrator.
Disguising foods does allow normally ingested quantities
to be taken with relative ease and in a natural manner,
but it can be difficult to produce preparations whose taste
is truly indistinguishable. Encapsulation of dried foods
avoids many of these disadvantages. Many commonly
incriminated foods are available in ready-dried form from ,
ordinary supermarkets and health food stores.
In practice it is best to take an eclectic approach.
Encapsulated food provocation is reproducible in children
and adults[29,30] and is the simplest and easiest tech-
nique. Most patients with genuine IgE-mediated hyper-
sensitivity react to small, easily encapsulated doses of
food. Milk is an exception. The amount of milk powder
needed for provocation in many adult patients would
require at least 30 capsules. The same dose is easily
disguised in a soy-milk 'shake'. The performance of
double-blind provocations with adequate doses of food to
disprove the contentions of some pseudo-allergy patients
can tax the ingenuity of the researcher, but is rarely
required as a routine.
It is simple to decide on the absence of an organic basis ?
when doses of food, which repeatedly induce reactions on
open challenge, fail to produce the same response when
given in an identical manner apart from their identity
being obscured. High placebo response rates in the
demonstrable absence of hypersensitivity to the placebo
substances, or reactions purely to the suggestion that a
particular food has been given, reinforce the presumption
that the responses to open administration were psycho-
genic. Unfortunately, it is not valid to be quite so
confident about drawing the converse conclusions. There
is a real possibility that apparent positive responses to
double-blind provocation could occur purely by chance.
Regrettably, the criteria which need to be applied before
one can accept the results of such tests as indicating
organic sensitivity have received inadequate attention.
Suggestion will produce measurable airway changes in
EXERCISE
f
GASTROINTESTINAL
MOTILITY
EMOTIONAL AROUSAL
L
f
SUGGESTION
SYMPATHETIC
PARASYMPATHETIC
^ r1
AUTONOMIC IMBALANCE
Mast cell
releasability
J
End-organ
hyperreactivity
J
SKIN
BLOOD-FLOW
NASAL
VASOMOTOR
CONDITIONED
REFLEXES
ASTHMA
Fig. 2. Psychophysiological influences in atopy.
156 Journal of the Royal College of Physicians of London Vol. 19 No. 3 July 1985
J
about 50 per cent of asthmatics. In our own experience,
the majority of both atopic and non-atopic adult patients,
subjected to double-blind testing, report subjective reac-
tions to about 50 per cent of provocations in series which
they believe will contain at least one dose of a food to
which they suspect they are allergic. The odds for the
correct identification by chance of each test dose are
therefore even. In this situation statistical tests on data
from a group can only indicate the probability of its
having at least one member performing better than
chance and do not allow any judgement concerning
particular patients. Consequently, for each individual, a
decision must be reached for each food on the basis of
repeat administrations whose number must be pre-selec-
ted according to the level of confidence considered accept-
able (Table 1).
Table 1. Probability of chance identification of blind food
provocations.
Probability P
Number of
provocations All correct 1 error all correct or
in series demanded allowed 1 error
2 0.250 0.500 0.750
4 0.063 0.250 0.313
6 0.016 0.094 0.109
8 0.004 0.031 0.035
10 0.001 0.010 0.011
These tests may be further confounded by two other
variables. First, quite independent exacerbations may
occur in patients with spontaneously fluctuating symp-
toms. Second, if the minimal possible dose is employed
for provocations (both to minimise risk and to maximise
compliance), the reaction induced in a genuinely hyper-
sensitive patient may sometimes be too minor to be
detected clinically. The effective level of sensitivity can
vary with time. To take these factors into account one
may wish to allow one or more errors in the identification
of either placebo or active preparation in a provocation
series. However, this will affect the total number of
administrations required to reach the desired probability
for correctly classifying the result (Table 1).
Double-blind feeding tests adjudged by strict criteria
are the only acceptable proof of the aetiological role of
food hypersensitivity in particular conditions and in
individual patients. However, in states in which the role
of foods is well established, it may be justifiable to make a
presumptive diagnosis without such measures. These
include syndromes in which typical histological changes
have been shown to be reliable indicators of specific
patterns of sensitivity (e.g. coeliac disease) and in infancy
prior to the subject's development of awareness. In our
own research we have accepted the presence of hypersen-
sitivity if the subject has identified correctly five or six
challenges in a series containing three active and three
placebo provocations. In effect this is a working compro-
mise between knowing that just over 1 in 10 such
conclusions will be erroneous and the difficulties of larger
numbers of tests.
IgE-Mediated Food Allergy
Patients with evidence of IgE-mediated food sensitivity
can present in a variety of ways[31,32] all of which have
long been associated with the atopic diathesis: with acute
anaphylaxis; less severe reactions in multiple organs; the
same allergic responses limited to a single 'shock organ'
(Table 2) and occasionally in children, with apparent
Table 2. Conditions in which role of IgE-mediated food allergy
has been confirmed.
Acute generalised
Angioedema, anaphylaxis.
Gastrointestinal
Lip, oral and throat tingling, itching, swelling.
Epigastric pain, vomiting.
Abdominal pain, bloating, diarrhoea, malabsorption.
Respiratory
Sneezing, nasal blockage, rhinorrhoea.
Asthma.
Skin
Urticaria.
(Eczema; pathophysiology uncertain).
emotional and behavioural changes secondary to the
physical changes of allergy which have themselves gone
unnoticed (e.g. screaming secondary to abdominal pain,
'hyperactivity' due to severe itching). The actual pattern
of response produced depends on the level of specific IgE-
sensitisation of each organ and on the dose of food
ingested. Some patients have different patterns of organ
involvement with different foods. Most develop increas-
ingly widespread symptoms as they eat larger amounts.
When reactions are limited either by low levels of sensiti-
sation or by small challenges, they are usually confined to
the gastrointestinal tract.
Food allergy is quite common in infancy and becomes
increasingly infrequent with advancing age. Follow-up
provocation studies have confirmed the tendency of
young children to outgrow their allergies[33,34]. Food
hypersensitivities present in late childhood have a greater
tendency to persist[34], IgE-mediated hypersensitivity to
food developing for the first time after childhood has
never been demonstrated.
Although there are anecdotal reports of reactions to
virtually every type of food, and despite the frequency of
positive skin tests and detectable serum IgE antibodies
against many, provocation testing indicates that most
clinically relevant food allergy is due to a very limited
range of foods, particularly milk, eggs, fish and legumina-
ceae (including soya and peanuts)[29,30,34-36],
Anaphylactoid Reactions
Much confusion in the literature on food allergy and
many present diagnostic difficulties can be traced to the
frequency with which non-immunological hypersensitivi-
ties produce the features of IgE-mediated reactions. The
most important of these are reactions to sulphur dioxide
and sulphiting agents, and the syndrome of sensitivity to
Journal of the Royal College of Physicians of London Vol. 19 No. 3 July 1985 157
salicylates and cross-reacting substances. Failure to re-
cognise the character and origin of these responses to
common additives can lead to a wide range of foods being
blamed mistakenly, or false classification of reactions as
non-organic if provocation is performed with the unadul-
terated food.
Virtually all asthmatics will respond to inhaled sulphur
dioxide with vagally-mediated reflex bronchospasm[37],
S02 itself and S02-generating sulphites and metabisul-
phites are used widely in food manufacturing and storage.
Quite high concentrations are common in fruit drinks and
home-fermented beer and wine. Concentrations sufficient
to induce asthma may be released into the air immediate-
ly above such products[38], or be absorbed from solution
across the buccal mucosa and subsequently enter pulmon-
ary gases[38], A small number of cases have been de-
scribed who suffer generalised anaphylactoid reactions to
ingested metabisulphites themselves[39,40].
Anaphylactoid reactions to aspirin (ASA) are common
and vary from severe, acute generalised reactions,
through asthma, to chronic urticaria[41-44], There is
often cross-reactivity with other drugs, particularly anal-
gesics, but also with a group of azo-dyes (e.g. tartrazine)
and benzoic acid derivatives[42-44], The latter two
groups are frequently added to foods and medicines as
colouring agents and preservatives. The syndrome is
probably a familial idiosyncracy inherited independently
from atopy even though it may not be expressed until
middle life. Major difficulties in identifying it and in
estimating its true frequency are the large number of
potential precipitants to be tested and the lack of any
obvious fixed pattern of cross-reactivity. A significant
number of patients with what appears to be an identical
syndrome tolerate aspirin itself. For convenience I have
used the acronym BAD-sensitivity (Benzoate-Aspirin-
Dye) although it must be recognised that individual
patients may react to only some of a group containing
more than 80 chemical substances[45].
Review of 250 Allergy Clinic Cases
To give some idea of the frequency with which different
patterns of food intolerance are seen and to compare their
importance with that of other allergies, I have reviewed
250 patients assessed by myself in our allergy clinic.
These were consecutive cases up to January 1985 and
exclude only children under 13 years and patients re-
ferred for inclusion in specific research protocols. This
clinic provides a general allergy service to South Man-
chester, but also receives a number of referrals specifically
for the investigation of food hypersensitivity from a wider
area. Diagnoses of inhalant sensitivities are based on
clinical pattern, supported by skin prick test results and
confirmed in cases of doubt by appropriate provocation
tests. Except in cases of urticaria, food or ingestant
hypersensitivity was confirmed by double-blind provoca-
tion unless: (a) there were repeatable classical atopic
reactions to open provocation that could be blocked by
double-blind cromoglycate and which were associated
with strong positive skin-prick tests to the food, or (b) in
salicylate sensitivity, if there was a history of anaphylaxis.
Table 3. Reason for referral in 250 consecutive allergy clinic
patients.
No.
Atopic conditions: asthma, rhinitis, eczema 136
Chronic urticaria without asthma or rhinitis 48
Wasp anaphylaxis 3
Non-atopic syndromes attributed to food allergy 44
Miscellaneous* 19
'Includes referrals for advice concerning future employment in asymp-
tomatic individuals with previous history of allergy, requests for advice
concerning prevention of allergy from prospective parents, drug re-
actions, etc.
The distribution of the patients according to the reason )
for their referral is shown in Table 3. Urticaria unasso-
ciated with asthma or rhinitis is dealt with separately i
because several forms of urticaria are clearly not related ?'j
to the atopic syndrome (although they are popularly
assumed to be allergic) and because it is our practice only I
to investigate further those patients who do not respond to
exclusion of benzoate food preservatives, salicylates and \
azo-dyes (BADs). *
Urticaria '
As shown in Table 4, 12 per cent of patients referred with
a diagnosis of urticaria actually had some other condition.
Of the remainder, 19 per cent had physical urticarias, 14
per cent recurrent attacks of acute urticaria, and 67 per
cent chronic urticaria. In 7 per cent of chronic urticaria
patients the disease had resolved spontaneously before
investigation, 54 per cent responded to a BAD-free diet
and 7 per cent to the further exclusion of dietary yeast;
half of the latter two groups had a clear history of i
reactions to analgesics. Only 12 per cent of patients with
urticaria had evidence of IgE-mediated allergy as a cause
of their problem and in none was this related to food;
three cases had episodes of acute urticarial reactions on
contact with house dust or grass pollen; two had urticaria
associated with either oral or vaginal thrush, immediate
positive skin tests to C. albicans, and responded to
appropriate anti-fungal therapy.
Asthma, Rhinitis, Eczema
Of the atopic presentation patients, four had mild eczema
alone, 35 rhinitis without asthma and 97 had various
degrees of asthma with or without rhinitis, eczema or
urticaria. Hypersensitivity to exogenous agents was im-
plicated in at least some symptom exacerbations in 94 per
cent of patients; eight had purely reflex non-allergic
vasomotor rhinitis or exercise-induced asthma. The fre-
quency of clinically relevant hypersensitivities is shown in
Table 5. House-dust mite was considered the predomi-
nant allergen responsible for the presenting complaints in
64 patients (48 per cent); 30 (22 per cent) had predomi-
nant hay fever/hay asthma and 50 (38 per cent) had two
or more clinically important allergies.
Excluding the ubiquitous minor bronchospastic re-
sponses to sulphur dioxide and sulphite-containing
158 Journal of the Royal College of Physicians of London Vol. 19 No. 3 July 1985
Table 4. Forty-eight patients referred for urticaria,
Physical Urticaria(8)
Recurrent Acute Urticaria (6) Chronic Urticaria (28)
Non-Urticaria (6)
Dermographic
Cholinergic
Cold-induced
Allergic
Idiopathic1
BADs syndrome2 15
Other drugs 4
C. albicans 2
Dietary yeast 2
Spontaneous resolution 3
Idiopathic persistent 2
Other rashes3
No rash4
salicylates and azo-dyes, 8 patients gave histories of analgesic reactions
'Rare, minor reactions: not investigated
2Response to dietary exclusion of benzoate preservatives,
JSeborrhoeic dermatitis, tinea corporis
4One case each of pruritis without rash as presentation of haematological disorder, hyperventilation syndrome and acarophobia
Table 5. Clinically relevant hypersensitivities in atopic patients
(No. = 132').
Dermatophagoides pteronyssinus
Grass pollen
Other seasonal allergens
Animals
Food hypersensitivity2
No detectable hypersensitivity
'Excluding patients presenting with skin problems alone
'Spontaneous resolution before 17 years in 2 cases
drinks, nine atopic patients (7 per cent) had definite food
hypersensitivity which persisted after the age of 16.
However, this was incidental in four cases, and food
reactions were relevant to the main presenting complaint
in only one of the four cases with evidence of food allergy
and in the four cases with BAD-sensitivity (i.e. 4 per cent
of the atopic group). In comparison, 37 of the atopic
patients (28 per cent) had symptomatic animal allergy,
which was the presenting complaint in 17 (13 per cent)
and the only allergy in 9 (7 per cent). Over the same
period we saw three patients with severe anaphylactic
reactions to stings.
Atopic Symptoms
It is worth considering some clinical features of atopic
patients with and without confirmable food hypersensiti-
vity for later comparison with the non-atopic groups.
First, patients with objective evidence of IgE-mediated
food allergy had recognised their sensitivity since child-
hood. It only presented a significant problem in a single
case and then only because he wished to be able to accept
the hospitality of his elderly parishioners so as to avoid
giving offence. In contrast, each of the BAD-sensitive
patients from this group suffered severe chronic symp-
toms as a result of their sensitivities and none had
previously recognised any consistent food-symptom asso-
ciation. Three of these patients had 'ulcerative colitis'
associated with asthma or eczema and three had severe,
uncontrolled late-onset asthma. The ninth patient from
this atopic group had mite-sensitive asthma and ques-
tioned whether her own lifelong painless diarrhoea could
be due to food when her best friend was found to have
coeliac disease. She was sensitive to cow's milk protein
without evidence of IgE-mediated milk hypersensitivity.
None of these patients admitted any acute changes in
psychological state during food reactions.
Objective evidence of food hypersensitivity was not
found in a further 19 atopic patients referred for its
investigation. In seven the question had been raised
tentatively by the patient or by their family or physician,
but without incrimination of any specific food. Two
patients initially suspected several foods which were later
tolerated on open reintroduction. Disturbingly, six
patients had had confident diagnoses made elsewhere
purely on the basis of clinical ecology techniques (2), skin
prick tests at NHS clinics (3), or privately performed
RAST tests (1). They had been advised to avoid several
foods which they could actually eat without any ill-effect.
Each was at clear risk of dietary deficiency diseases but
none had been offered the advice of a qualified dietitian.
In four patients with ostensibly atopic symptoms and
the putative label of food allergy the problem was consid-
ered predominantly psychiatric. One 14-year-old boy
suffered from Meadow's syndrome. His diet was severely
curtailed by his mother who refused to accept any
orthodox explanation or treatment for his very mild
allergic rhinitis. She was abetted in this by each of the
fringe 'allergists' and 'ecologists' she consulted. Adoles-
cent food fads and questionable aesthetics seemed more
likely than hypersensitivity in a very belligerent 15-year-
old girl who would eat only potato crisps. The behaviour
of two middle-aged nurses claiming to have multiple
allergies prevented any objective investigation but indi-
cated hysterical personality traits. Both had a wide range
of non-atopic symptoms in addition to rhinitis and
eczema. One was addicted to barbiturates and opiates,
and had self-induced Cushing's syndrome. The other,
who had been considered anorexic in her youth, and
whose multiple abdominal operations in different cities
may have been due to factitious illness, later admitted
that many of her 'allergies' were due to distaste.
Non-atopic Symptoms
Forty-one patients whose main symptoms were other than
those of classical allergic conditions were referred for the
investigation of food hypersensitivity. Five, who had not
themselves considered food triggers likely, were referred
because physical syndromes such as proctitis and mig-
Journal of the Royal College of Physicians of London Vol. 19 No. 3 July 1985
159
raine had proved resistant to ordinary treatments. Thirty-
six patients considered themselves to be suffering from
food allergy at the time they presented to our clinic. In
only three cases was there any evidence that any symp-
toms were related to food and in each these were non-
immunological exacerbating factors rather than allergic,
or of primary aetiological significance: two had migraine;
the third, an epileptic, blamed an increased fit frequency
on milk which she was subsequently shown to tolerate.
She had probably been suffering from the effects of the
large doses of caffeine contained in copious volumes of
milky coffee. There was positive evidence of psychological
disorder in all the remaining patients. Pseudo-food aller-
gy (PFA) will be considered separately by sex since there
were distinct differences in the syndromes presented.
Pseudo-food Allergy (PFA)
Symptoms
There were notable differences between the features
observed in young and middle-aged men. Food avoidance
was primarily moral and philosophical in four of the five
men under 35. Three were adherents of variations of
eastern religions, exhibited schizoid features, and de-
scribed bizarre reactions to foods. For example, one
described how fish made his blood cold and his skin 'slimy
and slithery' v The fourth was an obsessive body builder
who had been surprised by the change in his bowel habit
on trying to maintain an adequate calorie intake on his
new high-fibre vegetarian diet. The fifth young man had
hysterical features and obvious secondary gain in the
continuance of 'neurasthenia'. In contrast, the main
symptoms of three of the four men over 40 were those of
endogenous depression, although each had previously
rejected psychiatric explanations and treatments. The
fourth was recently bereaved and responded rapidly to
support and explanation of his mainly hyperventilatory
physical symptoms.
With one or two exceptions the clinical picture pre-
sented by the 24 female PFA patients was remarkably
consistent despite variations in the primary underlying
psychiatric disorder. They tended to be in their middle to
late thirties and early forties, middle class, articulate and
either housewives without young children or under-
employed for their level of intelligence. All were poly-
symptomatic and attributed overtly psychological
symptoms to their allergy, as well as physical symptoms
referable to several organ systems (Table 6). Most were
adamant that their symptoms were not 'psychological'
and many strongly denied being anxious or depressed
while at the same time volunteering that food was respon-
sible for panic attacks, agoraphobia, irritability, mood
swings, uncontrollable weeping and even suicidal
thoughts, etc. Many of the physical symptoms reported
by these patients were the recognised somatic concomi-
tants of anxiety or depression, but in most cases at least
some of the symptoms were the result of other distinct
non-allergic syndromes (Table 7).
Not all of these patients were examined formally by a
psychiatrist, but my impressions of these 24 females were
Table 6. Common symptom's in pseudo-food allergy.
Lethargy, tiredness, weakness,
'not well'
Depression, mood swings, irritability
Panic attacks
Parasthesiae, burning, itching,
'swelling'
Headaches, head tightness,
'migraine'
Aches and pains, 'arthritis'
Breathlessness, choking
Palpitations, chest pains
Bloating, swelling, pain
Heartburn, belching, nausea
Constipation, diarrhoea
Disturbed consciousness Lightheadedness, disorientation,
poor concentration or memory
Blackouts
General debility
Affective changes
Abnormal sensations
Cardiorespiratory
Abdominal symptoms
Table 7. Somatic syndromes in 24 female pseudo-food-allergy
patients.
Chronic hyperventilation syndrome1 10
Irritable bowel syndrome2 9
with associated urethral syndrome 3
Somatic features of depression3 7
History of non-food allergies4 7
'Typical symptom pattern associated with evidence of spontaneous hypocarbia or
symptoms reproduced on voluntary hyperventilation
2Defined as abdominal pain associated with bloating and distension, and with
constipation, diarrhoea or alternating constipation and diarrhoea in the absence of
any other organic bowel disorder
'Anergia-lethargy, psychomotor retardation, typical disturbances of patterns of
sleep, appetite etc. associated with depressed mood ,
'Includes mild perennial rhinitis, drug rashes
entirely in keeping with our earlier comparative study[46]
which showed that PFA patients suffer from the same
spectrum of psychiatric disorder as unselected new refer-
rals to a psychiatric out-patient department. Four female
patients from the present series had features suggestive of
a hysterical illness and nine had significant depression.
The six who responded to tricyclic anti-depressants cov-
ered the entire age range of the female PFA group (32-66
years). Four patients had short-term reactions to social
events or to intercurrent physical illness. The remaining
five patients, together with the non-tricyclic-responding
depressives, gave evidence of life-long neurotic personal-
ity traits: they tended to describe themselves as having
'ailed all my life' or of 'never having been what you'd call
really well'. Others tended to call them 'odd' or hypo-
chondriacal, although few would fit the formal psychiatric
definition of hypochondriasis.
The Generation of PFA
There are two main reasons which lead patients to
develop the false conviction that they are afflicted by
allergies. Regrettably, the first is failure on the part of
orthodox medicine, which leaves them vulnerable to the
second. Most of our PFA patients had suffered for months
160 Journal of the Royal College of Physicians of London Vol. 19 No. 3 July 1985
j or years from other well described syndromes which their
doctors had failed to recognise, or mismanaged. Once the
question had been raised, having failed to find any proper
provision for allergy within the National Health Service,
they turned to alternatives.
The two most common non-allergic syndromes in PFA
were hyperventilation and depression. There seems a
remarkable general unawareness of the features and
frequency of the chronic hyperventilation syndrome
(HVS)[47], of which about half our patients presented
obvious features. Four had been treated for 'asthma'
without there being evidence of airway obstruction and
many had received antihistamines or diuretics for dy-
saesthesiae such as 'itching' or the subjective feeling of
'swelling'. One was understandably distressed by the
diagnosis of hyperventilatory symptoms as multiple scler-
osis. Irritable bowel syndrome (IBS), the third common
condition in this group, had more often been recognised
previously but the ideas the patients had received about it
were surprising. In many cases predictable fluctuations in
* bowel habit related to fibre intake or the ingestion of
irritants (e.g. peppers) were taken as confirmation that all
their symptoms must be due to food.
> There can be little doubt that having become dissatis-
fied, these patients only turned to allergy as a possible
explanation because of recent widespread publicity about
the subject; more specifically, by that generated in the
marketing of 'clinical ecology'. This recent import from
the USA is a mystico-philosophical system of alternative
medicine which views illness as maladaptation to the total
environment ( = allergy). While based on a rejection of
the principles and logic of science[48], its pseudo-scienti-
fic publicity can seem persuasive to the nai've. Lists of
symptoms said to indicate the presence of food allergy in
ecology clinic leaflets distributed to health food stores and
in paperback books are virtually identical to those of
hyperventilation and depressive states. Some ecologists
apparently hold that psychiatric disorders are due to the
direct cerebral effects of food allergies 'unmasked' by
social stress. This is considered justification for the
administration of controversial (and expensive) anti-aller-
gic therapy in place of intervention in the factors which
led to the stress.
None of our PFA patients modified their diets because
of a spontaneous association of their symptoms with food.
Twenty-three were severely restricting their diet: three
because of multiple 'allergies' diagnosed by acupunctur-
ists; five by a clinical ecologist and 15 by self-diagnosis
?. after reading ecology clinic publicity leaflets or Not all in
the Mind[49], At least three of the women were amenorr-
hoeic as a result of their starvation.
> Several of the features of PFA, including its induction
simply on reading a book or leaflet, implicate high
suggestability[46]. As a specific illness PFA seems to have
several stages of evolution. Patients first become con-
vinced that food allergy must be responsible for physical
and/or mental symptoms for which they have received no
other explanation that they are able to accept. Symptoms
are not associated with specific foods at this stage. Most
then start to misattribute coincidental symptom exacerba-
tions to what was last eaten. Subsequently, suggestion
leads to psychogenic reactions on re-exposure to foods
previously associated with symptoms, and this becomes a
self-reinforcing event. In some PFA patients their belief
that they suffer from food allergy has the status of an
over-valued idea[46], They may persist in it despite
exhaustive investigations failing to reveal any precipitat-
ing food or despite receiving rational alternative explana-
tions. The placebo effect of food avoidance often produces
initial improvement, but the inevitable symptom recur-
rence leads, not to a rejection of the first diagnosis, but a
search for yet further foods to be avoided.
Reported food-symptom associations are sometimes
purely due to misattribution or biased reporting. Com-
parison of symptom diaries shows no actual change in
symptom frequency in some patients describing dramatic
relief on particular diets. If drawn to their attention this
may be rationalised as proof of the commercial adultera-
tion of the food supply. Some reactions may be due to
simple suggestion. The suggestive power of dietary ma-
nipulation was demonstrated in one of our earlier
studies[50], in which 50 per cent of IBS patients, who had
not previously considered themselves allergic, came to
consider foods which they later tolerated as being respon-
sible for their symptoms. However, the most common
mediator of psychogenic reactions in PFA is demonstra-
bly hyperventilation. In HVS the apprehension associ-
ated with ingesting a specific food may be adequate to
trigger an attack and the tendency to post-prandial
exacerbations exaggerated by the diaphragmatic splinting
of gastric distension.
Conclusions
True immunologically-mediated food allergy does occur
in adult patients but is uncommon and is a much less
important cause of asthma, eczema, urticaria and rhinitis
in adults than is sensitivity to house dust, pollens and
animals. Non-immunological hypersensitivities to food
constituents are both more common and often more
difficult to identify. Minor asthmatic reactions to S02 are
extremely frequent, but reactions to metabisulphites and
substances cross-reacting with aspirin (BADs) can be
dramatic. The latter can also produce severe chronic
symptoms and BADs sensitivity should be considered in
every patient with poorly controlled asthma, particularly
if of late onset or associated with gastrointestinal symp-
toms.
Subjective psychological and psychogenic somatic ad-
verse responses to food are more common than organic
intolerance. The only presently available valid evidence
of hypersensitivity is double-blind feeding but even the
results of provocation tests require critical appraisal. It is
clear that patients on diets for 'food allergy' are at severe
risk of developing dietary deficiency diseases. It is there-
fore crucial that these diets only be embarked upon when
justified by objective testing and that suitable dietary
supplements be prescribed whenever necessary.
The application of objective investigations to food
hypersensitivity has indicated that a number of different
allergic and non-allergic reactions are important in sev-
eral human diseases and also indicated a number of new
Journal of the Royal College of Physicians of London Vol. 19 No. 3 July 1985 161
directions for future research. In particular, since food
hypersensitivity is a common cause of gastrointestinal
disease in children and since GI symptoms are frequent in
organic food intolerance at all ages, the role of foods in
adult human gut disorders should be reassessed.
Acknowledgements
Table 1 is based on calculations performed by E. B.
Faragher, MSc, FSS, Senior Medical Statistician, With-
ington Hospital.
This article is based on a paper read at the Conference on
Allergic Disease held at the Royal College of Physicians in
March 1985.
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45. Schlumberger, H. D. (1980) Drug-induced pseudo-allergic syndrome as
exemplified by acetylsalicylic acid intolerance, in PAR. Volume 1. (ed P.
Dukor, P. Kallos, H. D. Schlumberger and G. B. West.) Basel:
Karger.
46. Rix, K. J. B., Pearson, D. J. and Bentley, S. J. (1984) British
Journal of Psychiatry, 145, 121.
47. Magarian, G.J. (1982) Medicine (Baltimore), 61, 219.
48. Randolph, T. G. (1976) in Clinical Ecology (ed L. D. Dickey.) pp. 9-
17 and 44-66. Springfield: Thomas.
49. Mackarness, R. (1976) Not all in the Mind, London: Pan.
50. Bentley, S. J., Pearson, D. J. and Rix, K. J. B. (1983) Lancet, 2,
295.
162
Journal of the Royal College of Physicians of London Vol. 19 No. 3 July 1985
|
PMC005xxxxxx/PMC5371143.txt | Histocompatibility: An Historical Perspective
ALISON MACLEOD, md, mrcp(uk)
Lecturer in Medicine, Department of Medicine, University of Aberdeen
( For the past two decades intensive study of the major
histocompatibility complex (MHG) has involved almost
every branch of clinical medicine. This gene complex
(known as the HLA system) is situated on the human
sixth chromosome and governs the acceptance or rejec-
tion of foreign tissue. Furthermore, products of this
system regulate the immune response and this may
explain the predisposition of those of a given HLA tissue
type to certain diseases.
The development of this field began in the latter half of
the last century, stimulated by interest in the evolution of
man. At that time biochemical methods were not suffi-
ciently sophisticated to study protein structure in detail
and serological techniques led to the discovery that
individual proteins in various animals are different and
unique to each species.
In 1875, Landois[l] reported that animals generally
died when they were transfused with blood from an
animal of a different species. Later Bordet[2] showed that
when red cells from another species were injected into a
rabbit the cells lysed, whereas red cells from another
rabbit did not. In a study of over 500 species Nuttall[3]
showed that the intensity of the lytic reaction between the
red cells of one animal and the serum of another was
related to the distance that the animals were apart on the
phylogenetic scale.
Landois also noted that even within a single species a
recipient's erythrocytes could be haemolysed by serum
from certain blood donors. This observation was not
developed further until agglutination reactions were used
by Landsteiner to define the human 'ABO' red blood,
group system[4]. Later in his Nobel lecture, Land-
steiner[5] suggested that an analogous system might exist
for tissue cells?compatibility within this system might
govern the acceptance or rejection of a tissue transplant.
He also predicted that serological reactions might be
employed to determine these antigens.
Early Animal Studies
Early work on transplantation showed that mice were
i resistant or susceptible to inoculated tumours according
to their strain[6,7] but that this predisposition was not
related to any visibly recognisable factor such as colour of
eyes or coat[8].
The first attempt at genetic analysis showed that the
closer the genetic relationship between the donor of
tumour cells and the recipient, the more likely the tumour
was to survive[9]. When well established inbred strains of
mice became available for study around 1930, more
accurate statistical analysis suggested that if simple Men-
delian genetics were applied, between four and 19 genes
were responsible for the acceptance or rejection of foreign
tissue[10,l 1], Sir Peter Gorer[12,13], showed that one
genetic locus was particularly important. Unlike the
human, the mouse possesses antigens coded for by this
locus on its red cells. Gorer, therefore, immunised rabbits
with red cells from inbred mouse strains in an attempt to
define blood groups and identified three red cell surface
antigens (antigens I, II and III). By backcross experi-
ments he showed that the presence or absence of antigen
II on murine red cells determined whether a tumour was
accepted or rejected.
Further work on transplanted tumours showed that
while an animal which had rejected one tumour rejected a
second tumour from the same donor more rapidly, a
transplanted tumour from an unrelated donor was unaf-
fected[14]. Sir Peter Medawar[15] confirmed this work
by showing that the second of two successive skin grafts
from the same donor was rejected more rapidly than the
first. Taken in conjunction with Gorer's work, these
results suggested an immunological basis for graft rejec-
tion which was under the control of specific genes, coding
for antigens such as antigen II. These genes were named
'histocompatibility' genes[16]. The prefix 'histo' was
used, as Snell[16] felt that the same genes which governed
susceptibility to transplanted tumours also controlled the
ability to accept or reject transplanted normal tissue. The
gene locus coding for antigen II was named 'Histocompa-
tibility^' or 'H-2' and was shown to be carried on the
seventeenth mouse chromosome[17].
The existence of other histocompatibility loci, as pre-
dicted by earlier workers, was confirmed, but their effect
on tissue transplantation was shown to be minimal[18].
The H-2 system was subsequently found to comprise
several genes[19], each of which has many possible
alleles[20] and became known as the mouse major histo-
compatibility complex (MHC).
The genes of the MHC coded for alloantigens ex-
pressed on tissue cells and they could be detected by a
complement dependent lymphocytotoxicity assay[21]. In
this test lymphocytes carrying a given alloantigen on their
surface were killed, in the presence of complement, by
serum containing alloantibody to that antigen. A modifi-
cation of this technique is currently used in human tissue
typing. Thus, as predicted by Landsteiner[5], a serologi-
cal test is currently used to define the antigens of the
major histocompatibility complexes of all species.
Journal of the Royal College of Physicians of London Vol. 19 No. 3 July 1985
169
The Human Major Histocompatibility Complex:
HLA
The human major histocompatibility complex was de-
fined in a different way, as human red blood cells do not
express histocompatibility antigens. Research in this field
developed from a search in the sera of leucopenic patients
for antibodies directed against white blood cells. Jean
Dausset[22] in 1952 was the first to find such antibodies
in the serum of a patient with agranulocytosis. The
patient's serum agglutinated leucocytes from normal
individuals and those from patients with chronic myeloid
and chronic lymphatic leukaemia. Similar activity was
found in sera from individuals who had received multiple
blood transfusions[23]. In a further study Dausset[24]
showed that leucoagglutinins were almost exclusively
present in the sera of leucopenic patient's who had
received blood transfusions from several donors. This,
taken in conjunction with the finding that sera from
leucopenic patients had no activity against syngeneic
cells[25], indicated that these leucoagglutinins were
isoantibodies which had developed as a result of 'immuni-
sation' by blood transfusion rather than autoantibodies
occurring as a feature of the underlying leucopenic
disease.
The first leucocyte antigen was defined after the sera
from patients who had received multiple blood transfu-
sions were tested against leucocytes from a panel of
normal donors[26]. Certain sera showed activity against
leucocytes of the same 11 panel members but not against
a further three. These sera, therefore, contained antibody
to a common antigen present in the 11 'positive' panel
cells but absent from the three 'negative' panel cells. This
first human histocompatibility antigen, present in 60 per
cent of the population, is now known as HLA-A2. All the
HLA antigens determined since have been defined by this
method of testing sera against lymphocyte panels.
A further advance was made when leucocyte antibodies
were found in sera from parous women[27,28]. These
sera agglutinated the leucocytes of fewer cell panel mem-
bers than the sera from transfused patients. They were,
therefore, more useful in determining whether leucocyte
surface antigens segregated into genetic groups analogous
to the ABO red blood cell groups. By computer analyses
of these serological reactions two independent allelic
antigen systems emerged and they were named 'Group
4'[29] and 'LA'[30],
Over the next few years work in this field accelerated
and many antigens in the new systems were defined. This
expansion was largely brought about by the establishment
in 1964, by Dr D. B. Amos, of International Histocompa-
tibility Workshops which resulted in the exchange of sera
between a large number of participating laboratories and
analysis of the extensive data produced.
As the number of new antigen specificities increased,
the need for agreement on nomenclature became appar-
ent. In 1967 the World Health Organisation set up a
Nomenclature Committee which named the human
major histocompatibility complex HLA (H for human, L
for leucocyte and A for the first system defined in man).
Payne's 'LA' system[29] was named HLA-A and van
Rood's 'Group 4' system[30] HLA-B. In 1971 a third
locus was suggested[31] which has subsequently been
named HLA-C.
The HLA-A, B and C gene loci code for antigens
expressed on most of the body's nucleated cells. As the
genes are co-dominant, each cell expresses on its surface
two antigens from each series, i.e. one inherited from
each parent. The combination of genes that codes for
antigens inherited from one parent is known as a haplo-
type. This term, derived from haploid phenotype, was
introduced by Cepellini in 1967[32]. The HLA gene
complex is markedly polymorphic; at the 1984 Histocom-
patibility Workshop 23 alleles were recognised at the A
locus, 49 at B, and eight at C[33],
The location of the HLA gene complex was defined in
1974[34]. In six members of a large family the centromere
of one of the sixth chromosomes occurred in an abnormal
position (pericentric inversion). These six family mem-
bers all shared the same HLA haplotype (HLA-A2, B12)
whereas this haplotype was not present in any of the seven ?>'
family members possessing a normal sixth chromosome.
The strong linkage of the HLA haplotype with this
chromosomal abnormality implied that the HLA gene
complex was situated on the human sixth chromosome.
Immune Response Genes and the HLA-D Locus
A fourth rather different locus was defined in a more
complex manner. In 1961 it was shown inadvertently that
when lymphocytes from two patients were incubated
together stimulation occurred[35], i.e. they underwent
DNA and RNA synthesis, blast cell formation and cell
division. This mixed lymphocyte reaction (MLR) was /
thought to be the in vitro homologue of allograft rejection.
In the mouse the MLR was indeed shown to be governed
by the major histocompatibility complex. Strain pairs,
identical except for a difference at H-2, displayed strong
stimulation whereas those H-2 identical but with multiple
non-H-2 differences gave weak stimulation[36]. Strong
stimulation between donor and recipient lymphocytes in
the MLR was shown to correlate with poor murine heart
transplant[37] and skin graft[38] survival. Using animal
strains differing at only a certain segment of H-2, MLR
control was localised to one end of the H-2 segment[39].
In initially unrelated studies it was shown that the
genes controlling the immune response to simple synthet-
ic polypeptide antigens (Ir genes) were linked to H-2[40],
More recently the Ir genes have assumed increasing
immunological importance and have been shown to play
a major part in regulating cellular immunity to virus
infected cells[41] and the response to tumour inducing
viruses[42]. Around this time it was shown that these Ir
genes also controlled the activity of the mixed lymphocyte
reactions[43]. The region of the H-2 complex in which
the Ir genes were located was named the I-region[44] and,
unlike the other regions of the mouse H-2 complex, it has
not been shown to code for any serologically defined
antigens. However, David[45] reported the development
of cytotoxic antibodies in one strain of mouse directed
towards lymphocytes of a strain differing only at the I-
region. These antibodies were cytotoxic to only 35 or 40 *
170 Journal of the Royal College of Physicians of London Vol. 19 No. 3 July 1985
per cent of splenic lymphocyte population and were
shown to be directed against antigens present mainly on B
lymphocytes[38], The antigens were named I-region-
associated (la) antigens[46] and were shown in the
mouse[47] and rat[48] to be extremely strong transplanta-
tion antigens.
Investigation of the human equivalents of the I-region
followed a similar path. Bach and Amos[49] observed that
MLRs between the lymphocytes of HLA identical sib-
lings were negative and thus showed that the mixed
lymphocyte reaction was governed by the MHC in the
human. Yunis and Amos[50] showed, however, that
MLRs between unrelated subjects who shared the same
four HLA-A and B antigens and thus appeared HLA
identical, were commonly positive. They therefore postu-
lated that the MLR was controlled by a gene separate
from the known HLA-A and B loci. This was confirmed
by similar studies on several recombinant families and the
MLR was shown to map outside the previously recog-
nised HLA region near the B locus[51]. It was named the
D locus at the Sixth International Histocompatibility
Workshop[52]. D locus typing was performed by incubat-
ing test cells with cells homozygous for known D locus
antigens; a negative response showed that the test cells
shared the D antigen carried by these homozygous typing
V cells.
Cepellini et al. [53] first observed that some HLA-A and
B typing sera could inhibit the MLR. This activity could
not be absorbed out by platelets[54], which carry HLA-
A, B and C antigens, suggesting that other antigens were
present. A higher frequency of reactions was also noted
against cultured lymphoblastoid cell lines[55] and cells
from patients with chronic lymphatic leukaemia, most of
whose lymphocytes are B lymphocytes, and it was sugges-
ted that such antigens were probably the human equiv-
alent of the mouse la antigens[56] and were expressed
solely on B lymphocytes. Over 100 sera with this pre-
sumed anti-la activity but without anti-HLA-A or B
activity were tested internationally against a variety of B
lymphocytes. The results defined eight main specificities
at this new serologically defined locus which was named
HLA-DR (D-related)[57],
HLA and Organ Transplantation
The evidence that HLA is the particular gene system
which governs acceptance or rejection of a human tissue
allograft came from experiments performed in the 1960s.
; k Intrafamilial skin grafts survived longer if donor and
recipient were HLA identical than if they shared only one
haplotype. The shortest skin graft survival occurred when
donor and recipient had no haplotype in common[58].
Successful renal transplantation was first performed in
<? 1954 when a kidney from one identical twin was trans-
planted to the other[59]. Over the next 10 years several
transplants between HLA identical siblings were carried
out and very few failures were reported[60,61]. An
analysis of the role of HLA in renal transplantation was
not possible until sufficient transplants had been per-
formed between different family members. Large studies
have now confirmed that a significant graded improve-
ment in allograft survival occurs when groups of donors
and recipients, matched for 0, 1 and 2 haplotypes, are
compared[62]. Family studies thus established the domi-
nant role of the HLA system in clinical transplantation.
HLA and Cadaver Donor Renal Transplantation
The results from the numerically more important group
of cadaver donor transplants are, unfortunately, more
difficult to interpret. Early studies showed that those
recipients well matched with the donor for HLA-A and B
antigens had significantly superior graft survival to those
poorly matched[63,64], Dausset[65] was the first to study
sufficient patients to show a progressive improvement in
transplant survival as the number of HLA-A and B
antigens common to donor and recipient increased from
none to four. Thereafter Paul Terasaki's laboratory in
Los Angeles analysed at intervals transplant survival data
from most of North America and also on certain occasions
from Europe and Australasia. Its analyses of several
thousand transplants[66,67] showed an overall effect of
HLA-A and B matching on graft survival but significant
differences between the matching subgroups were not
always demonstrated.
Similar results were found in other multicentre
studies[68,69]. In a recent analysis of worldwide
data[70], however, neither a graded improvement nor an
overall statistically significant correlation between the
degree of HLA-A and B matching and allograft survival
was found.
These reports have been criticised because they may
conceal differences in patient selection and therapeutic
policies practised by the individual transplant centres
submitting data. When single centres analysed their own
data a beneficial effect of matching for HLA-A and B
antigens was generally shown[71-74]. In several cases,
however, the small numbers dictated that the data be
analysed in groups, and statistical significance was not
always reached.
Thus, the data on HLA-A and B matching in cadaver
donor renal transplantation appear sufficiently strong to
support the concept that the HLA system is the human
major histocompatibility complex. However, the lack of a
consistent response between the degree of HLA-A and B
matching and graft survival diminishes the usefulness of
such matching as a means of selecting a kidney donor for
a given individual recipient.
The MLR takes six days to perform and therefore
HLA-D typing and MLR between donor and recipient
lymphocytes are not of value as predictive tests in a
cadaver donor transplantation. It is practical, however, to
perform HLA-DR typing prior to a cadaver donor renal
transplant although the preparation of the necessary B
lymphocyte suspension is time-consuming. The gene
frequencies for the eight well characterised HLA-DR
antigens account for 80 per cent of the Caucasian popu-
lation[58]. The HLA-DR locus is thus less polymorphic
than the HLA-A and B loci, and consequently if match-
ing for HLA-DR antigens also could be shown to improve
graft survival it would become easier to find a well-
matched donor for a given recipient.
Journal of the Royal College of Physicians of London Vol. 19 No. 3 July 1985
171
Several studies have now shown that HLA-DR match-
ing has a strong influence on graft outcome[75-79],
although one group has failed to confirm this. The
beneficial effect was shown by one group[77] to be
independent of any influence of HLA-A and B matching
and by another[81] to occur regardless of whether the
recipients had received blood transfusions prior to trans-
plantation or not. Traditionally most transplant centres
selected recipients for transplantation on the basis of
HLA-A and B matching. Recently, however, the United
Kingdom Transplant Service has altered its policy so that
donor kidneys may be requested on the basis of the HLA-
DR antigens shared with a prospective recipient.
Therefore, although the results of living related trans-
plantation have established the HLA complex as the
major influence on allograft survival, evidence from the
larger group of cadaver transplants is less convincing.
This implies that other areas of the HLA chromosome
remain to be defined. At the 1984 Histocompatibility
Workshop[33] recent data on the D region were critically
evaluated and it now appears that several sub-divisions
exist, analogous to those of the I-region in the mouse. In
addition to DR the Workshop named three further sub-
regions DP, DQ and DZ. Their role in transplantation
has not yet been evaluated.
Understanding of the human MHC has developed
rapidly in the last 20 years and the main stimulus to this
has been the need to improve matching of donor and
recipient for renal transplantation. More detailed evalua-
tion of the HLA-D region may not only be of further
benefit in the selection of transplant recipients but may
also establish that this region codes for genes controlling
the human immune response. If this can be confirmed,
studies of the HLA system and its products may help to
determine the pathophysiological basis of many disease
states, including immunologically related conditions and
malignancy.
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|
PMC005xxxxxx/PMC5371144.txt | The 'Langdons'?Three Distinguished Fellows
Langdon recurs in the names of John Langdon Haydon
Langdon-Down, Sir Walter Langdon Langdon-Brown
and Sir Geoffrey Langdon Keynes. It is therefore of
interest to enquire whether these three distinguished
Fellows of the College were related.
John Langdon Haydon Langdon-Down (1828-96),
remembered eponymously for his description of mongol-
ism in 1866, was the son of a Cornish apothecary, in
whose family tree the names Langdon and Haydon
frequently appear. John Langdon-Down's sister, Jane
Elizabeth Down, married the Reverend David Edward
Ford; their daughter, Ada Haydon Ford, married the
Reverend John Brown, whose son, Walter Langdon
Brown (1870-1946) became consulting physician to St
Bartholomew's Hospital and later Regius Professor of
Physic at Cambridge. When he was knighted in 1*935, he
altered his name to the hyphenated version, Sir Walter
Langdon-Brown. In his memory, his widow founded the
Langdon-Brown Lecture at the Royal College of Physi-
cians. Sir Walter Langdon-Brown was a great-nephew of
John Langdon-Down. John Langdon-Down's grand-
daughter, Stella Langdon Down, married another distin-
guished Fellow, Lord (Walter Russell) Brain, who was
President of the College (1950-57).
Sir Walter Langdon-Brown's sister, Florence Ada
Brown, married John Neville Keynes, whose two sons
were Lord (John Maynard) Keynes, the eminent econo-
mist, and Sir Geoffrey Langdon Keynes (1887-1983),
famous as both surgeon and man of letters. Sir Geoffrey
Keynes was a great-great-nephew of John Langdon-
Down, a cousin of Sir Walter Langdon-Brown and a
distant cousin of Lord Brain.
Alex Sakula
Fig. 1. Sir Walter Langdon-Brown.
Journal of the Royal College of Physicians of London Vol. 19 No. 3 July 1985
153
|
PMC005xxxxxx/PMC5371145.txt | Pathogenesis of Migraine Headache: Initiation
J. N. BLAU, MD, FRCP
Consultant Neurologist, The National Hospitals for Nervous Diseases,
Northwick Park Hospital and City of London Migraine Clinic, London
'The hereditary predisposition to migraine ? whatever
its nature ? can hardly be questioned'fl], A positive
family history has been used as a diagnostic criterion by
some clinicians[2], and geneticists[3] dispute only
whether a dominant or recessive gene is responsible.
Assuming a propensity to migraine is present at birth,
why should 10-30 years commonly elapse before head-
aches begin, and can anything cause attacks to start?
Patients may answer the second question spontaneously
when giving their history: they volunteer that the first
attack closely followed an emotional event or a physical
illness ? here called initiation. Some answer only when
asked directly; others have no recall for any antecedents
to the onset of their attacks.
Method and Patients
Forty-one females and 19 males (mean age 37, range 8-62
years) had had migraine as previously defined[2] and no
other headaches, for a mean of 18 years (range 4-40). Of
the 60 consecutive patients, 29 were able to specify events
that preceded their first migraine attack usually by several
weeks, occasionally by days or even minutes; they were
convinced that traumatic experiences ? physical,
emotional or a combination of the two ? were respon-
sible for starting their migraines.
Illustrative Case Histories
A 44-year-old national newspaper manager fell when
aged 8: not rendered unconscious he saw a 'starry
pattern' for a few seconds. Aged 14, the first night in the
dormitory of his boarding school, a master approached as
if to touch his genitalia. Within minutes the same pattern
reappeared, developed into a zigzag shape and was
superseded by severe headache. Subsequent attacks, 6-12
a year, all with this classical aura, were often provoked by
strife at work.
A 25-year-old receptionist had had her first attack two
years earlier within minutes of hearing by telephone that
both her parents had been sentenced to prison. Numbness
began in her right hand and in 5-10 minutes had extended
up the arm to her face. The sensory symptoms persisted
for 30 minutes and were followed by headache, photopho-
bia, nausea and vomiting. The whole episode lasted for
the remainder of that day, resolved during sleep but left
her feeling 'washed out' the next morning. Further
migraines then recurred with the same pattern at 1-2
month intervals following 'aggravation' at work or argu-
ments with her boyfriend.
A 34-year-old English teacher recalled two difficult
years in her mid-twenties when she had realised that she
was not going to succeed as an actress, a career for which
she and her widowed mother had striven for many years.
The patient described herself as 'almost anorectic', hav-
ing lost 3 stones in weight, and unable to tell her then
dying mother that she had had to take up teaching. Her
mother's death induced the first migraine. The patient's
interpretation was that the emotional turmoil and associ-
ated weight loss 'caused' her migraine.
These three and the remaining cases are summarised in
Tables 1-3.
Discussion
Migraine may begin at any time of life. In clinical
practice patients often state that the first attack occurred
Table 1. Physical initiation. CI = classic. Cm = common.
Cp = complete migraine[4].
Case Age Age at Sex Migrainelnitiating mechanism
no. now initiation type
1 39 29 F CI Started on contraceptive pill.
2 29 25 F Cm After birth of baby.
3 26 16 F CI After birth of baby and
starting on contraceptive
pill.
4 45 37 F Cm Vaginal haemorrhage, cause
unknown.
5 8 6 M Cm Knocked down by van, not
unconscious but dazed and
shaken.
6 39 20 M CI Head injury, not
unconscious but dazed and
large swelling on head.
7 13 6 F Cm Meningitis three months and
head injury three weeks
earlier.
8 39 28 F Cp Lack of sleep for 18 months
with difficult child. Head
injury one year earlier.
9 23 14 F CI Six weeks after onset of
Scheuermann's disease with
spinal and neck pain.
10 15 14 M CI 'Shooting up', grew 3 inches
in 6 months
166
Journal of the Royal College of Physicians of London Vol. 19 No. 3 July 1985
Table 2. Emotional initiation.
Case Age Age at Sex Migrainelnitiating mechanism
no. now initiation type
11 25 23 F CI Within minutes of hearing
that both parents sentenced
to prison.
12 50 24 M Cm Patient with brother who
drowned on holiday abroad.
Had to find and bring body
back to England.
13 47 32 M Cp Promoted in his company.
14 53 36 F CI Married, moved house to
troubled N. Ireland, father
died.
15 40 32 F Cm Fighting by own noisy
children.
16 24 16 F Cp First time away from home,
and examinations.
17 42 20 F CI Difficult final year at
college.
Table 3. Emotional and physical initiation.
Case Age Age at Sex Migrainelnitiating mechanism
no. now initiation type
18 50 14 M CI Head injury aged 8
provoked aura.
Schoolmaster attempted to
touch genitalia aged 14
produced first attack within
minutes.
19 34 24 F Cm Weight loss. Failure in
acting profession. Had to
change to teaching. Death of
mother.
20 33 12 F Cm Started menstruation for
which unprepared: felt 'dirty
and deeply embarrassed' at
boarding school.
21 58 11 F Cm First period a great shock,
thought 'something terrible
was happening'.
22 22 12 F CI Onset of periods and
difficulty with step-father.
23 27 12 M Cm Difficult puberty.
24 55 30 F Cp Emotionally and physically
low after third miscarriage.
25 37 21 F Cm Four months after marriage,
moved home, started on the
pill.
26 62 16 M Cm Started work; long hours
without food or drink.
27 34 22 F Cp Excess alcohol intake.
Learning to live on her own
in London.
28 44 26 F Cm Two to three months after
birth of baby, depressed,
started the contraceptive
pill.
29 36 17 F Cp Studying Russian very hard
on her own. Painful swollen
neck.
at puberty, after the birth of a baby (not always the first),
on taking the contraceptive pill or after stress[5,6], Such
beginnings, although noted and recognised, have not
been studied specifically.
Out of 60 patients, 29 had no doubt that specific events
had started their migraine. The vivid way incidents were
recalled and related left little doubt that the association
was real. Associations are admittedly not necessarily
causal, yet when the first migraine began within minutes
(cases 11 and 18) or days (case 12) of the event described,
it seems likely that more than a casual association was
present.
Initiation and precipitation of attacks are seen here as
two different processes. In this study some patients when
questioned recalled the precipitating factors of their first
attack. These were excluded from the 29 cases presented
here. Nevertheless, once attacks have begun, initiating
stimuli can also act as triggers for individual episodes: for
example, minor trauma like heading a football[7], or
change in sleep pattern, anxiety, excitement or 'skipping
meals'[8].
These precipitating factors are not unique to migraine:
they induce other headaches in non-migrainous subjects;
alcohol or excess sleep provide good examples. But the
same trigger does not invariably provoke attacks: thus
some women know that red wine precipitates migraine
only in the premenstrual week but not during the rest of
the menstrual cycle. Hence I have proposed a variation in
the milieu interieur that alters an internal threshold on
which triggers act: a migraine ensues only when a critical
level is reached[9].
We can now postulate three stages in migraine patho-
genesis:
1. Inheritance ? probably via one or more genes.
2. Initiation ? mechanism unknown.
3. Precipitation of individual attacks; stimuli that induce
headache in the non-migrainous population and migraine
in those who are predisposed.
Is migraine initiation laying down a memory? This
process could be likened to learning a symphony or riding
a bicycle, skills which, if firmly established, are rarely
forgotten. Pursuing the analogy, once a piece of music
has been learned, other stimuli can arouse the memory of
that tune. Applied to migraine, once attacks have been
initiated, say by trauma, subsequent episodes could be
precipitated by flashing lights or hunger, as found in this
series of patients.
Does the concept of initiation throw light on a neural or
a vascular basis for migraine pathogenesis[10]? Psycho-
logical initiation clearly favours a primary neurological
mechanism with secondary vascular manifestations, and
sustains Gowers' comparison of migraine with emotional
blushing or the pallor of fearfll]. Head injury, meningi-
tis, and local pains in the head or neck are neurological or
neurally transmitted stimuli. Migraine, beginning post-
natally, after a miscarriage or on starting the contracep-
tive pill, is more difficult to explain. However, nowadays
the 'director of the hormone orchestra' is seated in the
hypothalamus, and therefore is in keeping with a neuro-
logical pathogenesis.
Journal of the Royal College of Physicians of London Vol. 19 No. 3 July 1985
167
Conclusions
This study was aimed at deepening our understanding of
the aetiology of migraine. The ultimate cause is likely to
be genetic. However, the observations reported here
indicate that an intermediate step initiates a cerebral
process, perhaps a neuronal circuit, which, once estab-
lished, can be facilitated. Furthermore, it suggests that in
seeking the pathophysiology of migraine we ought to
concentrate on neurotransmitters and/or modulators
which may be multiple and complex because we are in the
realms of memory with an emotional context. If this is
correct, the site of the functional disturbance in migraine
could be in the cerebral cortex, with a final common
pathway acting through the hypothalamus to account for
the autonomic symptoms characteristic of migraine at-
tacks[10].
References
1. Refsum, S. (1968) In Handbook of Clinical Neurology, p.258. (ed P. J.
Vinken and G. W. Bruyn.) Amsterdam: North Holland Publishing
Company.
2. Blau, J. N. (1984) Lancet, 1, 444.
3. McKusick, V. A. (1978) Mendelian Inheritance in Man, 5th edn, pp.
144 and 516. Baltimore: Johns Hopkins University Press.
4. Blau, J. N. (1980) British Medical Journal, 281, 658.
5. Merritt, H. (1979)^4 Textbook of Neurology, 6th edn, p.833. Philadel-
phia: Lea and Febiger.
6. Diamond, S. and Friedman, A. P. (1983) Headache, p. 11. New
York: Medical Examination Publishing Company.
7. Matthews, W. B. (1972) British Medical Journal, 2, 326.
8. Leviton, A., Slack, W. V., Masek, B., Bana, C. and Graham, J.
R. (1984) Headache, 24, 182.
9. Blau, J. N. (1982) In Diseases of the Environment, p. 164. (ed A. R.
Rees and H. J. Purcell.) Chichester: John Wiley.
10. Blau, J. N. (1984)Journal of Neurology, Neurosurgery and Psychiatry, 47,
437.
11. Gowers, W. R. (1888) A manual of diseases of the nervous system, p.790.
London: Churchill.
|
PMC005xxxxxx/PMC5371146.txt | Information for the Physician
Knowledge is of two kinds. We know a subject ourselves, or we
know where we can find information upon it.
Samuel Johnson, Letters on the Scots, 18.4.1775.
The ethical responsibility of the physician postulates that
he should be concerned about all those whom he can help
by the practice of his skills. Thus his concern embraces
not only the patient who presents at any particular
moment, but patients on the waiting list and, beyond
that, potential future patients.
The exercise of this responsibility by the medical
practitioner has become increasingly important and com-
plex. Experience shows that he cannot delegate it to non-
medical professionals because his contribution is as
unique as it is essential.
The doctor's training and his day-to-day contact with
patients in the consulting room, in the clinic, by the
bedside, in diagnostic departments and operating theatres
are capable of affording him unrivalled insights into the
logistics of health care, particularly into the way resources
are employed and consumed. He will be aware of changes
in morbidity and patient characteristics, of changes in
treatment and regimes, and be able to understand and
explore the consequent clinical options with their differ-
ing resource implications.
However, the knowledge which he gathers in this way
remains largely fragmented, impressionistic and neces-
sarily personal. For this reason his cri de coeur, 'Give me
the tools and I will do the job', frequently remains
unheeded.
The economic situation, public expenditure policies,
necessarily crude national allocation formulae and in-
creasingly strict accountability reviews, side by side with
demographic changes and developments in medical tech-
niques, have brought about an unprecedented tension
between supply and demand, a tension which is most
cruelly felt at the operational level where care is being
delivered to patients. In this climate any request for
growth or shift in resource use must be justified by
detailed and quantified 'chapter and verse'.
The recommendations contained in the six reports to
the Secretary of State by the NHS/DHSS Steering Group
on Health Services Information provide the vocabulary
and the syntax for the required chapters and verses. They
lay a solid foundation for statistical systems that give
expression to important features of the patient population
being treated in NHS hospitals and community health
services and of the ways in which different types of
resources are being utilised to treat them. The basis is the
more solid for being grounded in data gathered at the
operational level, patient by patient, ward by ward,
specialty by specialty, by those who provide care; and for
having, as its chief aim, the use of the resulting infor-
mation by those who collect the data.
The usefulness of this information to the clinician is
greatly enhanced by the carefully specified, nationally ,
uniform definitions, classifications and methods of re-
cording, which allow him to draw various comparisons of i
interest to him: at clinical level or at the levels of
specialty, hospital, district and region. Comparisons at
these levels of the resource consumption by different
diagnostic/age/sex patient groups play an important part
in the thinking of allocators; clinicians are in a unique
position to elucidate the causes and effects of the often
puzzling and worrying variances which undoubtedly ex-
ist. Similarly, there is a special role for the clinician when
local data are set against and interpreted against epidemi-
ological and demographic information, and inferences
and extrapolations made about the present and future
organisation and funding of services.
Implementation of the Steering Group's proposals has
begun and is planned to be completed within the next
three years. This means not only that additional or
different data will be collected, but that computer pro-
grammes and analyses are being proposed, designed and
introduced which will determine the form, frequency and
degree of detail in which information will become avail-
able to those who need to use it. This is the first of two
important stages at which it is in the interest of physicians
to become involved in the process of information gather-
ing"
First, the Steering Group has confined itself to specify-
ing the minimum of data which are to be collected
nationally and physicians may need the introduction of
additional data locally to accord with local problems,
organisational arrangements or interests. Second, the
Steering Group has not?except in very rare instances?
laid down the format, frequency and degree of detail of
reports to users. Unless the individual physician takes
part in the development of the systems, he may not get
the information which he needs to do justice to his
circumstances and performance.
At the next stage, when agreed systems are in place, the
physician's role in maintaining the timeliness, complete-
ness and accuracy of the data becomes crucial. If he fails,
the work which he does will?as is now so often the case? ^
go unrecorded or recorded too late or so badly that the
information cannot be used. Such failure will inhibit his
effectiveness: for, unless he can unambiguously demon-
strate his case, he will not be doing his best for the
patients who are his concern.
Edith Korner, cbe
126 Journal of the Royal College of Physicians of London Vol. 19 No. 3 July 1985
|
PMC005xxxxxx/PMC5371147.txt | The Molecular Basis of Haemophilus
influenzae Virulence
E. RICHARD MOXON, MB, FRCP
Infectious Disease Unit, University Department of Paediatrics, John Radcliffe Hospital,
Headington, Oxford
t
A major milestone in medicine was the discovery that
germs cause disease and that particular clinical syn-
dromes may be characteristic of infections caused by
specific micro-organisms. Entrenched as is this notion in
clinical practice, it is sobering to recall that its discovery is
barely a century old. The criteria for causality of an
infection by a particular microbe are embodied in the
postulates of Robert Koch; an invariable association of
the microbe and the disease in question and that the
microbe should cause an identical infection when reintro-
duced into a susceptible animal after first being cultured
through several generations in vitro. As with many shib-
boleths, particularly when all criteria are not rigorously
applied, embarrassments occur. So it was that Gram-
negative rods were seen so frequently in the sputum of
individuals with influenzal pneumonia in the pandemic of
1889-92 that these bacilli were considered to be its cause
and were named Haemophilus influenzae[\\. It was not
until 30 years later that Andrewes discovered that influen-
za was caused by a virus[2], by which time the appellation
of Haemophilus influenzae was well established. However,
H. influenzae is no idle pretender; it causes a wide
spectrum of infections, especially in childhood, including
meningitis, septic arthritis, pneumonia and empyema,
otitis media, epiglottitis and cellulitis. Of these, meningi-
tis is of particular importance because of its potential,
even with appropriate supportive and antibiotic treat-
ment, to cause lasting neurological damage[3]. Deafness,
convulsions, mental retardation, hemiplegia and other,
sometimes subtle, neurological deficits have been recog-
nised. The occurrence of these apparently permanent
neurological sequelae in a substantial proportion of survi-
vors of H. influenzae meningitis is partly attributable to
the fact that this disease occurs almost exclusively in
children aged less than four years and, in particular, in
infants and children of less than two years in whom the
brain is in a critical phase of development. The impact of
H. influenzae meningitis has been well studied in the USA
where approximately 10,000 cases occur each year[4].
Table 1 summarises the morbidity and mortality from
this disease based on studies from North America. Attack
rates in the United Kingdom may be somewhat less, but
recent data[5] indicate that the incidence of H. influenzae
meningitis is not dissimilar from that observed in the
USA and the few studies which have been done to assess
Table 1. Long-term neurological residua from H. influenzae
meningitis.
Sell[22] Feigin[23]
(n = 86) (n = 86)
% %
Significant residua1 30.2 8.0
Possible residua2 14.0 28.0
None detected 43.0 64.0
'IQ<70, seizures, hearing loss (severe), motor deficits, or partial blindness
2IQ 70-90, hearing loss (mild), speech problems, or behaviour problems
its impact on English children indicate that it is equally
serious[6].
Our understanding of the biochemical basis of the
pathogenicity of H. influenzae stems from observations
made more than 50 years ago; strains of H. influenzae that
cause meningitis are almost always encapsulated[7], In ^
fact, H. influenzae may make any one of six chemically
distinct polysaccharide capsules and the antigenic differ-
ences mediated by these capsules is the basis of serotyp- j
ing, i.e. types a-f or non-typeable. It is remarkable,
however, that the majority of cases of meningitis are
caused by type b strains whereas other types or non- .
capsulated strains rarely cause meningitis. A further long-
standing observation is, that susceptibility to H. influenzae
meningitis is strongly correlated with absence of serum
antibodies to type b capsule[8,9]. This, with the experi-
mental data[ 10,11 ], makes the circumstantial evidence
that the b capsule is a major virulence factor extremely
strong. Based on these facts, it seemed entirely logical to 1
attempt prevention of H. influenzae meningitis by using
the purified type b capsular polysaccharide, polyribosylri-
bitol phosphate (PRP) as a vaccine. Indeed, a similar
approach had been used to prevent serious infections
caused by encapsulated Streptococcus pneumoniae and Neis-
seria meningitidis[ 12,13]. However, PRP proved to be
insufficiently immunogenic to raise protective levels of
serum antibodies in young children in whom the highest
incidence of H. influenzae meningitis occurs[14].
The failure of this logical approach to immunisation
suggested the need for developing alternative strategies
for prevention. These depend upon more thorough un-
derstanding of how host and microbial determinants of
174 Journal of the Royal College of Physicians of London Vol. 19 No. 3 July 1985
i
I
I
I
the infection determine the pathogenesis of meningitis.
Thus, the aim of studies conducted in my laboratory?
formerly at the Johns Hopkins University and more
recently in Oxford?is to understand the molecular basis
of H. influenzae pathogenicity. Virulence is a complex
biological phenomenon and a sine qua non for its study is
the availability of a biologically relevant model infection.
For if one says that a bacterium is virulent, one must ask
for whom? Conversely, from the host's point of view, if
an animal is susceptible to a micro-organism one must ask
to what? Ideally, one should strive to understand these
questions at the molecular level. It has been shown that
infant rats provide a biologically relevant model of H.
influenzae meningitis[15]. Based on several years of
studies, many features of the pathogenesis of H. Influen-
zae meningitis have been elucidated. If virulent type b
organisms?e.g. strains cultured from the CSF of chil-
dren with H. influenzae meningitis?are inoculated in-
tranasally, the nasopharynx becomes heavily colonised
and, within hours of the challenge, organisms enter the
blood stream. Type b organisms are able to evade
clearance by the spleen, liver and other reticulo-endothe-
lial organs which mediate the clearance of blood-borne
bacteria. If sufficient organisms circulate for a sufficient
duration, the probability of meningitis is high. In fact, a
striking correlation exists between the magnitude of
bacteraemia and the occurrence of meningitis. The impli-
cations of this latter finding, borne out by experimental
observations, is that a major determinant of meningeal
invasion resides in those microbial factors which confer
upon H. influenzae resistance to phagocytic clearance
from the blood stream. However, it needs to be empha-
sised that isolating one stage in the pathogenesis and
assigning to it a pivotal role is over-simplistic, for these
events must be placed into an appropriate biological
context. Thus, virulence is dependent on the interaction
of many different bacterial genes with those of the host.
Indeed, those bacterial genes which determine blood-
stream survival are not necessarily the same as those
which mediate lodgement in the nasopharynx, or deter-
mine the translocation of organisms from the nasopha-
ryngeal lumen to the blood, or the invasive process which
results in penetration of the blood/central nervous system
barrier. In fact, several putative virulence factors have
been identified (Table 2) and others probably exist of
Table 2. Putative determinants of virulence potential in H.
influenzae.
Capsular polysaccharide
Lipopolysaccharide
Outer membrane proteins
Pilus proteins
IgA, proteases
which we are not yet aware. The challenge is to sort out
the role of each and a logical way to do this is by taking a
genetic approach. If the genes or sets of genes which
determine the expression of these putative virulence
factors are identified, strains can be constructed which are
sufficient or deficient in expressing one or more of these
attributes. This genetic manipulation, i.e. the construc-
tion of isogenic strains, has become a practical possibility
through the availability of cloning and recombinant DNA
techniques. This strategy is outlined in Fig. 1. One
constructs a gene library which must be searched to
isolate recombinant phage which possesses one or more
genes relevant to the expression of a particular virulence
factor. When the relevant cloned DNA has been charac-
terised, it can be introduced in modified or unmodified
form into haemophilus by DNA transformation. This
provides a method for constructing isogenic strains that
can be used for virulence studies, the results of which
should provide an unambiguous indication of the role of a
particular gene or set of genes in determining virulence.
Now this broad approach is relatively simple when
dealing with virulence mediated by an enzyme or perhaps
a toxin since these polypeptides are usually coded for by
only one or two genes; such is the case for the sub-unit
pilin, individual outer membrane proteins and the IgAl,
proteases of Haemophilus influenzae. Thus the gene library
can be searched using a radio-labelled probe to identify
DNA clones expressing the protein. This was the ap-
proach used to clone a gene for an IgA1; protease of H.
influenzae[ 16]. However, the situation is much more
complicated when one is attempting to clone the genes for
expression of capsular polysaccharide or lipopolysacchar-
ide. A logical approach to identifying these genes would
need to be based upon an understanding of the enzymes
controlling their biosynthesis, cytoplasmic transport, pol-
ymerisation and surface assembly. Furthermore, the co-
ordinated expression of these genes is likely to be under
the influence of complex expression mechanisms, i.e.
bacterial surface antigens are prone to be both switched
on and off as well as to exhibit antigenic variation[17], A
further fact which must be taken into account is the
location and organisation of the genes on either chromo-
somal or extra-chromosomal DNA. The major possibili-
ties are considered in Fig. 2. Based on the results of
transformation experiments it seemed clear that only the
first two possibilities were likely. High molecular weight
DNA was extracted from a virulent type b strain and used
as the donor for transformation. The average size of the
donor DNA in such an experiment was approximately
40,000 base pairs. By carrying out the transformation
under conditions in which donor DNA was limiting,
transformants resulted from the uptake of a single mol-
ecule of DNA. Thus, it could be concluded that genes
necessary for b capsule expression were linked.
This approach was used to generate a series of transfor-
mants which have provided a series of genetically similar
strains for comparative virulence studies. Experimental
infection of rats showed that the type b transformant was
significantly more virulent as evidenced by both the
incidence of bacteraemia and the quantity of organisms
recovered from the blood. Furthermore, each of the
transformants, representing the different capsular sero-
types, had the potential to reach the blood stream, thus
indicating that the greater virulence of the type b trans-
formant resided in its greater ability to survive in the
bloodstream. Since meningitis is a function of magnitude
Journal of the Royal College of Physicians of London Vol. 19 No. 3 July 1985
175
1 Isolation of virulence (Vi + ) gene
Haemophilus
influenzae
DNA
Charon 4
DNA
EcoR I
Cohesive end ligation
In vitro phage packaging
Amplification in
Escherichia coli
Ill
2 Construction of isogenic virulent (Vi + ) and avirulent (Vi
H influenzae by DNA transformation
Vi
Log phase
(VI ) H influenzae
Vi
Integration of VI+
by recombination
to produce transformant
Competence
Regimen
Vi
Vi-
Donor
DNA
Competent
(Vi ) H influenzae
VI
Uptake of cloned DNA
containing Vi*
J
3 Virulence assay in experimental model infection
Intranasal inoculation
Asymptomatic colonisation
Systemic infection
Fig. 1. General scheme for studying pathogenicity of H. influenzae. Fragments of chromosomal DNA are cloned into a suitable
vector to isolate virulence genes (Panel 1). These genes can be introduced by DNA transformation into H. influenzae strains which
lack the specific virulence determinant (Panel 2). Transformed and untransformed H. influenzae are then compared in a suitable
animal model, e.g. infant rats (Panel 3) to allow an unambiguous analysis of the role of specific genes in pathogenicity.
176 Journal of the Royal College of Physicians of London Vol. 19 No. 3 July 1985
of bacteraemia[18], the data suggested that acquisition of
type b capsule plays a critical role. But there is reason for
caution in this interpretation; did transformation result in
the acquisition of genes other than those coding for type b
capsule? To examine this question, we studied the outer
membrane proteins (OMP) and lipopolysaccharide (LPS)
phenotypes of the transformants, these being two obvious
cell surface antigens that might contribute to pathogen-
icity. Whereas the OMP of the transformants were
similar, the LPS phenotypes were distinctly different[19].
Thus, transformation apparently caused altered expres-
sion of not just capsule, but also LPS.
This experiment illustrates why alternative approaches
are necessary to examine critically the independent role of
capsule and LPS. This is not straightforward, since both
LPS and capsule expression are each the function of
several genes.
To analyse the contribution of type b polysaccharide,
the approach was as follows: capsulated strains produce
non-capsulated, single-step mutants at rather high fre-
quency (approximately 0.1 per cent). From a sectored
colony, we obtained a stable capsule-deficient mutant
(Sec-1) and then screened our lambda gene library for
recombinant phage which possessed DNA inserts which
would transform this capsule-deficient recipient to cap-
sule production. Thus, some lambda clones had the
ability to restore the typical, iridescent colonial phenotype
to the capsule-deficient recipient. One such recombinant,
designated Charon 4:48[20] consisted of a 13.4 kb insert
of haemophilus DNA. It was mapped using restriction
enzymes and shown to have two Eco RI fragments of 9
and 4.4 kb. These were subcloned into pBR322 and used
as donor DNA for transformation of the capsule-deficient
strain, Sec-1. In this manner, we were able to show that
Sec-1 has a mutation which maps to a 1 kb region within a
4.4 kb Eco RI fragment[21]. By Southern hybridisation,
it was also shown that the mutation involves either a very
small deletion or rearrangement in this 1 kb region. Thus
a comparison of the virulence of these two strains is
informative, since they apparently differ in the expression
of a single gene, a gene which is necessary but not
sufficient for type b capsule expression. The type b strain
was virulent, whereas Sec-1 was not. The result was not
unexpected, but provided rigorous proof of the essential
role of b capsule in virulence expression.
It has also become apparent that altered expression of a
cell wall antigen (most probably LPS) is also critical to
virulence expression. To search our library for a clone
involved in LPS expression, we made use of the fact that
LPS mutants often have an opaque phenotype; a lambda
clone from our library, designated Charon 4:169, was
isolated. This clone contains an appx. 10 kb Eco RI
fragment which was capable of producing a transformant
(Rd/b + /I69) which retains full capsule expression, no
definite alteration in OMP but a definite change in LPS
phenotype. When the parent strain and its 169 transfor-
mant were compared in virulence experiments, the trans-
formant failed to produce bacteraemia and meningitis
whereas the parent strain was fully virulent[19]. One
difference between the parent and transformed strains is
that the 169 transformant is rapidly cleared from the
bloodstream following intravenous inoculation, whereas
the untransformed parent survives very efficiently. Thus,
expression of both type b capsule and LPS appear to be
critical, independent determinants of the bloodstream
survival of H. influenzae.
These experiments indicate an approach to the analysis
of microbial virulence and how this approach could
amplify our basic understanding of the molecular mecha-
nisms of bacterial virulence. Ultimately, one hopes that
this approach will facilitate the development of novel
approaches to prevention of important infections. In a
sense, as Stanley Falkow has observed, Koch's postulates
can be modified so as to have a molecular ring to them.
For we should now aim to isolate virulence genes, amplify
them in their respective vectors, re-insert them into an
avirulent strain and demonstrate the re-acquisition of
pathogenicity and the potential of that organism to
produce classic disease.
Acknowledgements
I would like to thank Ellen Huggins for preparation of the
manuscript. Professor E. R. Moxon is supported by a
Programme Grant from the Medical Research Council.
This article is based on a paper read at the College Regional
Conference in Oxford in September 1984.
References
1. Pfeiffer, R. (1892) Deutsche Medizinische Wochenschrift, 18, 284.
2. Smith, W., Andrewes, C. H. and Laidlaw, P. P. (1933) Lancet, 2,
66.
3. Rodriguez, L. P., Schneerson, R. and Robbins, J. B. (1972)
Journal of Immunology, 107, 1071.
4. Brachman, P. S. Letter to State and Territorial Epidemiologists
from Department of Health, Education and Welfare, Public Health
Service, dated 2 May 1978.
5. Communicable Disease Report (1985) Weekly edition, No. 14.
6. Ware, S.J. and McLaughlin, S. (1978) Lancet, 2, 197.
7. Pittman, M. (1931) Journal of Experimental Medicine, 53, 471.
8. Fothergill, L. D. and Wright, J. (1933) Journal of Immunology, 24,
273.
Fig. 2. Hypothetical possibilities for arrangement of genes for
type b capsule expression. It is assumed that several genes (the
choice of 8 is arbitrary and speculative) are required for the
biosynthesis, transport, polymerisation and surface assembly of
the ribosyl-ribitol phosphate polymer. These might be arranged:
A. as a linear cluster of genes; B. closely linked, but with two or
more clusters interspersed by genes unrelated to capsule expres-
sion; C. widely dispersed so that genes are not linked.
Journal of the Royal College of Physicians of London Vol. 19 No. 3 July 1985
177
9. Anderson, P., Pitt, J. and Smith, D. H. (1976) Infection and
Immunity, 13, 581.
10. Moxon, E. R. and Vaughan, K. A. (1981) Journal of Infectious
Disease, 143, 517.
11. Gigliotti, F. and Insel, R. A. (1982) Journal of Infectious Disease, 146,
249.
12. Austrian, R. (1981) RevieJbs of Infectious Diseases, 3, (Suppl.), SI.
13. Gotschlich, E. C., Liu, T. Y. and Artenstein, M. S. (1969) Journal
of Experimental Medicine, 129, 1349.
14. Makela, H., Peltola, H., Kayhty, H. et al. (1977)Journal of Infectious
Disease, 136, S43.
15. Moxon, E. R., Smith, A. L., Averill, D. R. and Smith, D. H.
(1974) Journal of Infectious Disease, 129, 154.
16. Bricker, J., Mulks, M. H., Plaut, A. G., Moxon, E. R. and
Wright, A. (1983) Proceedings of the National Academy of Science USA,
80, 2681.
17. Meyer, T. F., Mlawyer, N. and So, M. (1982) Cell, 30, 45.
18. Moxon, E. R. and Ostrow, P. T. (1977) Journal of Infectious Disease,
135, 303.
19. Zwahlen, A. J., Winkelstein, J. A. and Moxon, E. R. (1983)
Journal of Infectious Disease, 148, 385.
20. Moxon, E. R., Deich, R. A. and Connelly, C. (1984) Journal of
Clinical Investigation, 73, 298.
21. Hoiseth, S. K., Connelly, C.J. and Moxon, E. R. (1985) Journal of
Bacteriology, in press.
22. Sell, S., Merrill, R., Doyne, E. and Zimsky, E. (1972) Pediatrics,
49, 206.
23. Feigin, R. D., Stechenberg, B. W., Chang, M. J. et al. (1976)
Journal of Pediatrics, 88, 542.
|
PMC005xxxxxx/PMC5371148.txt | I.
An Introduction to Allergic Disease
MANSEL HAENEX MB, MSc, MRCP(UK), MRCPath
Consultant Immunologist, Subregional Department of Immunology, Hope Hospital, Salford
In Western countries, allergic diseases affect over 15 per
cent of the population and impose a substantial physical
and economic burden on the individual and on society.
We are all endowed with the components needed to
produce an allergic reaction, namely immunoglobulin E
and other antibodies, mast cells, basophils, lymphocytes
and pharmacological mediators. What is unclear is why
some people never show an allergic response, why some
have an occasional mild reaction, why some suffer life-
long debilitating allergic disease or, more rarely, why
others react with severe and sometimes fatal anaphylactic
shock.
In 1906, Von Pirquet defined allergy as 'a specifically
altered state following exposure to antigen', a term that
?> covered both untoward and beneficial immune responses.
By common usage over the years, however, allergy has
come to mean a disadvantageous immune response to
extrinsic antigens. With the introduction of the Gell and
Coombs classification of hypersensitivity reactionsfl], the
term allergy became almost synonymous with hypersensi-
tivity of the immediate IgE type[2].
However, the clinician who regards allergic disease
merely as an IgE response to a specific antigen will have
to reconcile many anomalies. Not all allergic reactions are
> IgE-mediated; other types of antibody and delayed hyper-
sensitivity responses are sometimes evident. Further-
more, non-sensitised individuals can develop severe,
immediate, adverse reactions to drugs and chemicals
without evidence of a specific immune reaction of any
kind-pseudo-allergy.
Immediate Hypersensitivity Responses
Immediate hypersensitivity reactions usually occur fol-
lowing the interaction of antigen and specific IgE anti-
body.
Biological Properties of IgE
IgE has the Y-shaped structure common to all classes of
immunoglobulin. The Fab fragments enclose the antigen-
binding sites and the Fc portion contains those determi-
nants that make IgE a unique class of immunoglobulin.
Certain aspects of IgE antibody synthesis are unusual
compared with other immunoglobulin classes[3j. First,
IgE antibodies are present only in minute amounts in the
serum; this is true even in allergic individuals, although
their circulating levels may be many thousand times
higher than normal. Second, IgE is synthesised locally in
the respiratory and gastrointestinal mucosa, suggesting
an important role for such antibodies in protecting the
host against agents likely to invade at these sites. Third,
the antigens which readily stimulate IgE production differ
in some ways from antigens stimulating responses of
other immunoglobulin classes: for example, parasitic
nematodes usually induce high titres of IgE antibodies
whereas bacteria and viruses usually stimulate high titres
of IgM and IgG antibodies but not of IgE.
The bulk of IgE in any individual is bound to the
surface membranes of circulating basophils and tissue
mast cells, via surface receptors recognising determinants
in the Fc portion of the e-chain of IgE (FceR). The
receptor is a glycoprotein of three sub-units: a, available
to the extracellular environment; (3, and a y component
believed to be linked to the (3 component, both of which
are embedded in the plasma membrane and might pro-
trude into the intracellular environment. Each mast cell
possesses between 1 and 3 x 105 free binding sites[4].
The IgE bound to the target-cell surface is presumed to
present its antigen-binding sites (Fab regions) to the
micro-environment of the cell and is thus still able to react
with specific antigen. The binding of IgE molecules by
basophils and mast cells is very strong; this high affinity
compensates for the low serum levels of IgE and its rapid
catabolism (half-life of two days), allowing the biological
activity of cell-bound IgE to persist much longer than in
the free state.
The Mast Cell
Recent studies suggest that mast cells originate from
pluripotential bone marrow cells under the influence of a
specific thymus-dependent lymphocyte growth factor[5].
The mast cell is ovoid (length 10-30 /xm) and contains
many dense cytoplasmic granules. Evidence, based upon
fixation characteristics, electron microscopic variations,
staining responses, mediator content and response to
pharmacological agents[6,7] indicates that mast cells are
heterogeneous.
Mast cells are widely distributed but are noticeably
present in connective tissue, particularly surrounding
blood vessels and nerves. In the lung, for example, over
80 per cent of pulmonary mast cells are located in and
around the airways, with the highest density being found
in the peripheral airways. While most bronchial mast cells
are located in the submucosa, it is those cells superficial to
the basement membrane which assume particular import-
ance in the pathogenesis of antigen-induced airways
Journal of the Royal College of Physicians of London Vol. 19 No. 3 July 1985 147
constriction, since they are the cells that first become
exposed to inhaled antigens[8].
Triggering of Mediator Release
It is generally accepted that the release of biologically
active mediators is triggered when an antigen molecule
interacts with two adjacent cell-bound IgE antibody
molecules, so forming a bridge composed of IgE-antigen-
IgE. This implies that the antigen must possess repeating
antigenic sites per molecule, with a minimum of two sites.
This interaction induces conformational changes in the
cell surface membrane, activating intracellular enzyme
systems and culminating in the release of the mediators of
acute hypersensitivity. However, mediator release can
also be induced by pre-formed IgE-antigen complexes,
polymerised IgE without antigen, Fc fragments of IgE
and by anti-IgE antibodies, suggesting that antigen is not
always required for mediator release. More recently, it
has been shown that the Fee receptors on the cell surface
and their bound IgE molecules migrate as a complex on
the cell membrane. Bridging of cell-bound IgE molecules
will also bring these receptor sites into close proximity.
Mediator release from mast cells can be triggered by
antisera raised against the exposed regions of the IgE
receptor sites[9] and by the (Fab')2 fragments of these
antisera[9], but not by the Fab fragments, implying that
it is the binding of a pair of receptor molecules which is
primarily responsible for the activation of membrane-
associated enzymes.
Non-IgE Triggered Release of Mediators
Non-IgE triggered release of mediators can cause clinical-
ly relevant disease: some known non-immune factors
include naturally occurring endogenous substances (such
as acetylcholine, a-adrenergic substances, prostaglandins
and complement components) and exogenous chemicals
and drugs which act by poorly understood mechanisms.
These include some intravenous anaesthetic agents,
radiocontrast media and plasma volume expanders. In
most instances, prior exposure to the drug is not required
and IgE antibodies are not involved. The most likely
explanation is that such agents either directly activate the
complement system, with release of the complement-
derived anaphylatoxic fragments C3a and C5a[10], or
directly trigger basophils and/or mast cells.
In most, if not all, allergic individuals, there is some
degree of non-immune triggering in addition to the
classical IgE-mediated release of chemical mediators.
Effects of Mediators
Mediators liberated from mast cells and basophils may be
pre-formed (that is, present in cytoplasmic granules ready
for release) or newly generated (that is, synthesised
following the triggering stimulus and after the release of
pre-formed mediators). Pre-formed mediators include
histamine, lysosomal enzymes and proteases, neutrophil
chemotactic factor, eosinophil chemotactic factors and
heparin. Other mediators are newly generated from
arachidonic acid via the cyclo-oxygenase and lipoxygen-
ase pathways: these include prostaglandins (especially
PGD2), thromboxanes, leukotrienes (LT) and platelet
activating factor. The slow-reacting substance of anaphy-
laxis (SRS-A) is now known to be composed of a mixture
of LTC4, LTD4 and LTE4, all of which have biological
activity. These mediators all contribute to the variable
clinical features of acute hypersensitivity.
Late Phase Response
It has long been known that a 'delayed' reaction can
occur following mast cell degranulation. This late phase
response begins 4-6 hours after the initial reaction, peaks
around 12 hours and lasts 24 hoursfll]. Such late re-
sponses are IgE-dependent and most frequently affect the
lung and skin, which show a cellular infiltrate that
includes eosinophils, basophils, mononuclear cells and
neutrophils.
Regulation of IgE Antibody Synthesis
Genetic Control
Different strains of laboratory animals vary greatly in
their capacity to produce IgE antibody after specific
immunisation. Most strains require a large dose of
antigen to produce an IgE response which, when it
occurs, is transient and usually cannot be boosted by
further antigenic exposure[12,13], a situation rather anal-
ogous to non-atopic humans. In contrast, certain strains
develop unusually high levels of IgE antibody following
immunisation with small doses of antigen and are capable
of producing secondary responses as well[14], a situation
similar to the atopic state in man.
In the mouse, the capacity to develop high titres of
persistent IgE antibody to an antigen is genetically
controlled and linked to the major histocompatibility
complex (MHC) situated on chromosome 17[ 15,16].
Genes determining high responsiveness are dominant
over those coding for low responsiveness to the same
antigen. However, a strain which is a high responder to
one antigen may be a low responder to a different,
unrelated antigen. In humans, it has been postulated that
analogous genes exist linked to the MHC (HLA) on
chromosome 6. Evidence suggests that one such gene
controls the immune response to ragweed antigen E[ 17]:
thus, segregation analysis of two large families with atopic
disease indicated autosomal dominant inheritance of sea-
sonal ragweed allergy, the locus for this trait being HLA-
linked.
Regulation by T Lymphocytes
Rats which normally produce high-titre IgE antibodies
following immunisation with an appropriate antigen can-
not do so if they are subjected to neonatal thymectomy
before immunisation[18]. This defect can be overcome by
giving normal thymocytes to the thymectomised animals,
showing that thymus-derived lymphocytes are needed for
the development of an IgE antibody response. Further-
148 Journal of the Royal College of Physicians of London Vol. 19 No. 3 July 1985
more, co-operation between both T and B lymphocytes is
essential for the synthesis of specific IgE antibodies[19-
21]. While these studies illustrate the need for T lympho-
cyte participation in IgE antibody responses, the more
intriguing question is what mechanisms normally prevent
or minimise the development of excessive IgE antibody
synthesis in strains of animals belonging to the low IgE
responder phenotype. These strains do not have an innate
> incapacity to respond since experimental manipulations,
such as appropriate doses of whole body irradiation[22],
administration of some anti-T-cell antisera, or certain
, immunosuppressive drugs[23] can convert these animals
from low to high IgE production. The enhanced IgE
responder animals can be converted back to poor re-
sponders by the passive transfer of T cells from normal
litter-mates[24] or by soluble factors derived from these
cells[25]. The implication is that regulation of IgE anti-
body synthesis is dominated by a suppressor T cell
regulatory or 'damping' mechanism which limits the
extent of IgE antibody production following antigen
sensitisation.
On the basis of this experimental evidence it has been
argued that a defect of suppressor T cell function under-
lies the atopic diathesis in man. The evidence for this
hypothesis rests on the observations that elevated IgE
levels are found in a number of primary diseases with
\ impaired thymus dependent immunity[26] and patients
with certain diseases characterised by markedly raised
IgE levels, such as the hyper-IgE syndrome or acute graft
versus host disease, have reduced numbers of circulating
suppressor T cells. However, no convincing reproducible
differences have been demonstrated in suppressor T cell
numbers and function in atopic subjects compared with
controls[27], although in vitro IgE synthesis by lympho-
cytes from atopic subjects can be suppressed by the
addition of T lymphocytes from non-atopic individ-
uals[28,29].
Regulation of IgE Synthesis by T Cell Derived Soluble Factors
.
Numerous studies of rodent models have demonstrated
specific T cell factors which selectively enhance or sup-
press the IgE response [see reviews 3,30,31]. In particu-
lar, Ishizaka and co-workers have shown that T cells
bearing Fc receptors for IgE (FceR+) produced these
IgE-binding regulatory factors[32-34].
Recently, Marcelletti and Katz[35-38] have identified
a new family of soluble mediators termed IgE-induced
regulants (EIR), each of which participates in precise
, steps and on distinct cellular targets involved in regulat-
ing the IgE system. Exposure to IgE in vitro induces T
and B lymphocytes to express FceR and to secrete EIR
that regulate FceR expressed by other lymphoid cells.
The remarkable feature of this complex regulatory net-
work is the pivotal role played by the IgE molecule itself;
it initiates the sequence of events and seems to control the
eventual magnitude of its own production.
In man, only a very small proportion (< 1 per cent) of
circulating FceR + lymphocytes have been detected in
non-atopic subjects, but the percentage is higher in
allergic individuals[39,40]. It has recently been shown
that activated human T lymphocytes also release IgE
binding factors following incubation with IgE[41], al-
though the functional roles of these factors are currently
less well-defined than in the rodent model.
Pathogenesis of the Atopic Trait
An important insight into the aetiology of allergic disease
was the observation that allergies tend to run in families.
In 1923, Coca introduced the term 'atopy', best defined
as a tendency, subject to hereditary influence, to spon-
taneously produce high levels of IgE antibodies to com-
mon environmental antigens.
Several theories attempt to explain why some individ-
uals produce IgE antibodies to common environmental
antigens while others do not. The increased incidence of
IgA deficiency in atopic individuals and an increased
incidence of atopy in IgA-deficient subjects have lead to
the suggestion that a qualitative or quantitative deficiency
of IgA at mucosal surfaces allows the absorption of
excessive amounts of antigens capable of stimulating IgE
synthesis.
However, it has been argued by Jarrett [42] that the
stimulation of the immune system by antigen absorbed
across mucous membranes, far from evoking deleterious
IgE responses, normally maintains the IgE regulatory
mechanism in an active state throughout life. An IgE
response would occur only when the amount of antigen
absorbed was below the threshold needed to stimulate
IgE-suppressive mechanisms: this threshold would be
very low in normal individuals but much higher in atopic
subjects. Factors which influence the development of IgE
suppressive immunocompetence include: first, factors
inherent in the constitution of the individual?the genetic
determination of maturity of the immune system with
time and the eventual capacity to regulate IgE and other
antibody responses; second, factors relating to antigen
exposure?the form, dose, frequency and time of stimula-
tion relative to the stage of immunological maturity; and
third, the influence of the immune response of the
mother.
It is an attractive idea that maternally transferred IgG
may compensate for immaturity of the IgE regulatory
system of the normal infant. Immunisation of female rats,
for instance, induces a marked suppression of IgE respon-
siveness in their progeny, a state which persists for many
weeks and well beyond the time that maternal antibody
can be detected in the circulation[43]. It has therefore
been suggested that one function of transferred maternal
antibody is to suppress the IgE-responsiveness of the
young animal to the potential antigens in its environ-
ment.
Administration of antigen to rats early in life, whether
or not they have maternal antibody, also suppresses IgE
responses[44]. As in the rat, IgE responses may be
suppressed in both normal and atopic human infants fed
with relatively large amounts of cow's milk, whereas very
small amounts stimulate rather than suppress the re-
sponse[45,46].
Experimental work on animals has led Katz to propose
a concept termed 'allergic breakthrough'[3,30]. This
Journal of the Royal College of Physicians of London Vol. 19 No. 3 July. 1985 149
concept also considers that IgE production is normally
kept at a low level following sensitisation by a damping
mechanism which reflects the net balance of the suppres-
sive versus enhancing factors involved. If, when some
disturbance depresses the damping capacity beyond a
critical level, the individual is simultaneously exposed to
one or more appropriate antigens, the allergic break-
through could result in excessive IgE antibody production
specific to the relevant antigens, and the subsequent
development of symptoms. In addition, the genetic pre-
disposition of any individual must be considered as
capable of response to the antigens concerned.
In children, onset or exacerbation of allergic disease
often follows a viral respiratory infection. It is possible
that upper respiratory tract infections are a common
though transient cause of perturbation of the damping
mechanism. In one prospective study, the onset of clinical
and immunological evidence of allergy in children of
allergic parents usually coincided with, or closely fol-
lowed, upper respiratory tract infection, most commonly
with para-influenza virus, respiratory syncytial virus or
cytomegalovirus[47]. Certain endogenous events (e.g.
marked shifts in steroid hormone production) can also
contribute to changes in those regulatory mecha-
nisms[48].
Delayed Hypersensitivity
It is now recognised that mast cells and basophils are also
involved in delayed hypersensitivity responses. In mice,
the expression of delayed-type hypersensitivity is critical-
ly dependent upon mast cells[49]: delayed hypersensiti-
vity is preferentially elicited in sites rich in mast cells;
mast-cell deficient strains of mice show poor delayed
responses; and delayed responses are inhibited by drugs
that either block mediator release by mast cells or deplete
mediators.
It has been suggested[49] that activated T cells release
an antigen-specific factor, quite distinct from IgE, that is
transported via the blood to sensitise tissue mast cells.
Upon meeting antigen, for instance at a site of contact
antigen challenge, these mast cells release vasoactive
amines which open gaps between adjacent endothelial
cells and increase vascular permeability. Once this early
response has occurred, other antigen-specific T cells enter
the site, interact with antigen presented by Langerhans'
cells and induce the late response. This late response is
independent of further mast cell mediator release but
depends on the ability of these T cells to release chemo-
attractant lymphokines that recruit bone marrow-derived
circulating leukocytes to infiltrate the reaction site. This
early component of delayed-type hypersensitivity is opti-
mal about two hours after antigen challenge. Many
studies of delayed hypersensitivity have overlooked the
early component and the biphasic nature of classical
contact allergic dermatitis in experimental animals. Mast
cell degranulation and the formation of endothelial gaps
in delayed hypersensitivity reactions in man[49] suggest
that an analogous process may well be involved in human
contact dermatitis.
There appears to be an inverse relationship between
the frequency of mast cells and basophils in various
species. It has been suggested that both are supplemen-
tary cells with similar functions but the basophils, being
quickly-mobilised, short-lived cells, represent an appro-
priate initial response in delayed reactions, while in the
more chronic responses in man they give way to mast
cells[50], This certainly appears to occur in renal allograft
rejection, allergic contact dermatitis and atopic derma-
titis[51].
Diagnostic Tools in the Investigation of Allergic
Disease
There is no substitute for a thorough history. A detailed
history should suggest a provisional diagnosis and indi-
cate the most suitable procedures needed to confirm this
diagnosis. Two important questions are whether allergic
symptoms are seasonal or perennial and whether they are
worse indoors or outdoors.
Seasonal allergies in the UK are usually caused by
pollens and, in general, trees pollinate first, followed by
grasses and then weeds. Moulds sporulate during the
grass and weed pollen season; this may cause diagnostic
difficulty since moulds occur on both indoor and outdoor
plants. Perennial allergies are most likely to be caused by
house-dust mite, foods, animals and yeasts.
Although a family history of atopic disease will rein-
force other evidence of an atopic trait, it will not provide
any clue as to the specific sensitivities of the patient under
investigation.
Laboratory Investigations
All laboratory tests can be graded according to their value
in the care of patients. Some tests are essential for
diagnostic or prognostic purposes, some are useful, while
others are of interest only for research purposes. Some
tests are absolutely useless if requested in inappropriate
circumstances.
Total IgE Levels
A raised serum IgE level provides an objective measure of
an atopic state but gives no pointer to the cause of the
symptoms. IgE levels will, however, help to identify the
patient at risk, whether or not he or she is symptomatic.
While many variables other than IgE contribute to the
clinical features of allergy in adults or older children, the
serum IgE level alone may be a helpful diagnostic and
predictive tool during the first two years of life[52]. At
this early age, the distinction between atopic and non-
atopic individuals is much clearer. In the atopic child the
serum IgE level rises earlier and climbs higher than in
normal children. Total serum IgE levels can therefore be
of value in infants and neonates with a positive family
history of atopic disease and in infants with troublesome
symptoms of suspected allergic origin[53,54].
The diagnostic value of serum IgE determinations in
adults and older children is less clear-cut. High serum IgE
levels often accompany atopic disease, particularly
asthma, seasonal allergic rhinitis and atopic eczema. The
150 Journal of the Royal College of Physicians of London Vol. 19 No. 3 July 1985
levels seem, in general, to be related to antigen exposure;
the longer the period of exposure and the more antigens
the patient is sensitive to, the higher the IgE level.
Serum IgE levels show a wide variation. Some 'nor-
mal' individuals may have raised IgE levels, but a low
serum IgE does not preclude an allergic aetiology. Occa-
sional patients are sensitive to one antigen: as a result,
total IgE may be normal while skin tests or radio-
, allergosorbent tests are positive.
Nevertheless, approximately two-thirds of non-atopic
subjects but only 2 per cent of atopic patients have IgE
levels below 20 U/ml. In contrast, almost two-thirds of
atopic patients have levels in excess ol 100 U/ml[55],
Serum IgE concentrations are also raised in non-atopic
conditions, particularly parasitic infestation, and quoted
'normal' ranges for Europeans may not apply to residents
from zones where parasites are endemic.
Measurement of the total IgE level is not essential in
any clinical condition; instead it should be considered a
rough diagnostic tool, most useful when the clinical
picture is ambiguous or other test results are difficult to
evaluate. In clinically convincing cases of allergy, the test
adds nothing.
Antigen-specific IgE Antibodies
The most widely used technique for detecting and mea-
suring antigen-specific IgE antibodies is the radio-allergo-
sorbent test (RAST: Pharmacia Diagnostics). The RAST
procedure is simple. A paper disc labelled with antigen is
incubated with a small amount of test serum. After
washing the disc to remove free unbound IgE, radio-
labelled anti-human IgE is added. After further washing
to remove free, unbound, radioactive label, the level of
radioactivity attached to the disc is measured, the amount
of antigen-specific IgE being directly related to the counts
obtained. The use of a specific antiserum to human IgE
means that antibodies of other immunoglobulin classes
are not recognised in this assay.
RAST results are interpreted by comparison with a
reference sample run in parallel and classified as negative
(class 0), borderline (1), positive (2), strongly positive (3),
or very strongly positive (4).
The diagnostic value of RAST is often assessed by
comparison with skin testing and nasal or bronchial
provocation tests. While the overall agreement between
RAST and such tests is about 75-85 per cent, agreement
is higher in patients with moderate to severe hypersensiti-
vity but considerably lower for milder hypersensitivity.
The usual type of discordance is a positive RAST with a
negative skin or provocation test. In most cases, the mild
degree of hypersensitivity detected by RAST is of doubt-
ful clinical importance. In some cases, however, a nega-
tive RAST is found in a patient with positive skin or
provocation tests, highlighting the danger in assuming
that serum IgE specificities necessarily reflect those of
tissue-fixed IgE.
The interpretation of RAST results is hampered by a
number of pitfalls, (a) The commonly used commercially
available kit yields results related to a single reference
serum. For this reason, comparison with other results is
almost impossible, (b) RAST classes for different antigens
are not comparable, (c) Most antigen preparations are
impure or inadequately defined, (d) Antibodies of other
immunoglobulin classes, particularly IgG, can interfere
with IgE binding.
RAST assays are expensive and time-consuming. They
are not essential in any clinical condition and have a
limited role in the investigation of patients with putative
allergy[56]. Skin testing is a cheaper and quicker way of
identifying those antigens to which the patient can mount
an IgE-mediated reaction. RAST testing need only be
performed when skin testing is unreliable or contraindi-
cated: for example, in very young children; in patients
with severe and extensive eczema or dermographism; in
those in whom symptomatic treatment may influence skin
reactions; in patients with exceptionally high levels of
sensitisation in whom even skin testing is potentially
hazardous; and in some patients with 'food allergy' where
skin testing may be unreliable. Properly used, RAST
testing can reduce the frequency of provocation tests.
Skin Tests
Prick testing is a traditional and sensitive diagnostic tool
in allergic disease. The assumption is made that skin
responsiveness reflects and correlates with the reactivity
of the mucous membranes of the bronchi, nose and other
target organs. However, there is no clear evidence that
this is so.
Many factors can affect prick test reactivity. Variability
in the potency of antigen' extracts may be considerable
among batches from different suppliers or even in lots
from the same source. Differences in the stability and
purity of extracts also affect biological potency, and the
preservatives used to improve stability and prevent con-
tamination, for example phenol, can have non-specific
irritant effects. The magnitude and reproducibility of the
response is often influenced by the biological variability of
the skin. In healthy individuals, skin reactivity is greatest
at about the third decade and declines from the fifth
decade onwards; skin reactivity may vary with circadian
rhythms and menstrual cycles and, in the presence of
dermographism, there will be positive skin tests to all
antigens, including negative saline controls.
Despite these hazards, clinical studies have shown that
prick tests provide good specificity (few false positives)
and good sensitivity (few false negatives) in patients with
moderate or high degrees of sensitisation.
Histamine Release Assays
Human basophils which have fixed IgE antibodies will
degranulate on the addition of specific antigen; degranu-
lation can be scored morphologically or by measuring
histamine release. In practice, basophils from a normal
(non-allergic) individual or animal cell preparations (rat
mast cells, chopped monkey lung) are passively sensitised
with serum from an allergic patient. Although the method
is reliable when performed with appropriate controls by
experienced investigators, present application of the
method is limited by the need for large volumes of fresh
Journal of the Royal College of Physicians of London Vol. 19 No. 3 July 1985 151
blood (or animal tissue) to provide sufficient numbers of
functioning basophils.
Provocation Tests
Target organ challenge with a suspected antigen is, in
theory, the best test of allergy because it most closely
simulates the physiological effect of natural exposure. As
routine clinical procedures, however, provocation tests
are of limited value because they are time-consuming,
affected by the medication being taken by the patient, and
cannot be used in a symptomatic patient. In the case of
bronchial provocation tests, a major source of misleading
results is the tendency of some patients with hyper-
reactive airways to respond to numerous non-immuno-
logical stimuli, such as impurities or preservatives in the
antigen extracts.
Nasal challenge is useful in patients with a history
suggestive of allergic rhinitis. Some patients have nega-
tive RAST or skin tests yet show positive reactions to
nasal challenge, reflecting the ill-defined nature of these
antigens and the varying potencies of available extracts.
Specific IgE antibodies, can sometimes be demonstrated
in the nasal secretions. Major problems with nasal provo-
cation tests include their lack of value if the nasal mucosa
is already congested, or if the patient is taking medica-
tion, the subjective nature of the criteria required for a
positive result and the need to limit testing to one antigen
at a time.
Food allergy often presents a difficult diagnostic prob-
lem. A high index of clinical suspicion is required, since
skin tests with dietary antigens, total IgE levels and
RAST often fail to correlate with the clinical picture. A
diagnosis of food allergy can be confirmed only by
observation of symptomatic relief on dietary withdrawal
of the offending food and the return of symptoms follow-
ing food challenge.
Unorthodox Tests
There are a number of other tests which, in spite of
numerous and sometimes extravagant claims, have never
been shown to be of value[57,58]. These include pulse
testing, sublingual food testing, leukocyte cytotoxicity,
intradermal skin testing and bogus methods such as
radionics, radiesthesia, radionic hair testing and hair
trace metal analyses[58].
Conclusion
The appreciation of early and delayed aspects of IgE
mediated allergic reactions and the involvement of mast
cells and basophils in delayed-type responses suggest that
conventional immunological dogma separating immedi-
ate and delayed hypersensitivity from one another by
focusing on their time course and suggesting that they are
unrelated may no longer be adequate to explain the
manifestations of allergic diseases.
The identification of factors regulating IgE synthesis
gives hope of a potential therapeutic handle for future
manipulation of the IgE antibody system. The recent
I
availability of long-term T cell lines and T cell hybrid-
omas which secrete IgE binding factors should make it
possible to characterise these factors and study their
modes of action.
This article is based on a paper read at the Conference on
Allerpic Disease held at the Royal College of Physicians in
March 1985.
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|
PMC005xxxxxx/PMC5371150.txt | Priorities in Medical Care
EDITED REPORT OF A CONFERENCE HELD AT THE COLLEGE
MARCH 1985.
Welcoming the participants, the President, Sir Raymond
Hoffenberg, said the aim of the conference was to bring
together doctors and experts in other fields to discuss one
of the wider medical issues. The problem of priorities in
medical care was urgent, as there had to be a limited
expenditure on health care. Good housekeeping could
save some money but sooner or later there would not be
enough money to pay for all resources. There was implicit
acceptance that some form of rationing was inevitable.
Rationing could occur without planning but there could
be an earnest attempt to rationalise the rationing.
The financing of medical care would be addressed by
Mr A. Harrison, co-editor of Public Money and by Mr D.
W. Pace, Regional Treasurer of the South West Thames
Region. The adequacy of medical care would be dealt
with by Professor R. E. Klein, School of Humanities and
Social Sciences, Bath. The moral and ethical problems
would be discussed by Canon G. R. Dunstan, Depart-
ment of Theology, University of Exeter, and Professor I.
McC. Kennedy, Professor of Medical Law and Ethics,
King's College, London. Finally, how we manage would
be discussed by Sir Douglas Black, Mr R. Nicholls,
formerly President of the Institute of Administrators and
Dr June Crown, District Medical Officer, Bloomsbury
Health Authority.
The Financing of Medical Care
Mr Harrison said that rationing was inevitable in the
system of financing health care in this country. The
overall priorities were set by a small group of people
meeting in Downing Street, the people that picked up the
bill were the tax-payers, those who used the money were
the professionals within the NHS and all were liable to be
clients or users of the service but not necessarily as tax-
payers at the time. So there were four groups of people,
each of which might have their separate views on what the
overall priority should be, and there was no reason to
suppose that the views and priorities at the global level
would coincide. In 1984 Social Security Planning Re-
search carried out a large-scale survey of public attitudes
and showed that people were prepared to pay more for
more and better social services. Many people had put the
NHS as their first or second choice of where extra
government expenditure should go. So there was already
tension in that people wanted more health care than the
government was ready to provide, and further tension
between the providers and the consumers who might be
refused care that they knew could be available.
The present system of public finance by which the
NHS was funded acted as a constraint on what could be
done. Was the pressure induced by that constraint likely
to relax, increase or stay the same? One view held that
there was no real problem about public spending in the
medium term. If the government was to hold the line
right across the public sector, then a little bit of growth in
the economy would make money available for public
spending and it could be diverted to health if this was the
first priority. If the government wished, provided it held
the line on other spending programmes, it could divert
large extra resources to the NHS or it could reduce
taxation by an equivalent amount. With the present
government, a reduction in taxation was more likely than
an equivalent sum being given to the NHS. However, it
would be difficult for any government in power to devote
a vast amount of extra resources to health care. Nearly
anything any government did, be it for health, the arts,
defence or social security, became more and more expens-
ive. Real costs tended to rise, partly because of advancing
technology and partly because many services were labour
intensive and their costs rose with a general rise in
incomes. The case for social security was a little different,
but if those receiving its benefits were to be kept more or
less in line with the incomes of the rest of the community
there was a built-in cost increase. Ten years ago there did
not appear to be a public spending problem if the line was
held. However, programmes had expanded in real terms,
with higher standards as well as costs. It was unrealistic to
expect any government to hold the line on all its spending
programmes and give priority to a particular one. Press-
ures of all kinds would build up for the spending of money
on all fronts and not just one. Therefore it seemed
unlikely that the financial rationing of the NHS would be
relieved by much.
There were other financial strategies that might make
the problem of rationing easier for those who had to
manage resources within the NHS. The charges could be
increased, but only by a modest amount if the concept of
the NHS was not to be subverted. This was a limited
method of choking off demand before it entered the
system. Fiscal measures could be used to influence behav-
iour. As an example, the cost of road accidents to the
NHS was estimated to be about ?100,000,000. An at-
tempt to reduce the pressure of those costs would be for
the insurers to be charged for the full amount. Insurance
premiums would then be so high for high-risk road users
that they would not be able to afford to drive and so the
number of road accidents should drop. In the same way it
Journal of the Royal College of Physicians of London Vol. 19 No. 3 July 1985 127
had been suggested that industries that were particularly
dangerous to their workers should pay extra National
Insurance charges, giving a built-in incentive to reduce
the industrial risk. However, these policies would only
make a minor contribution to the NHS.
There were sources of income other than tax which
could supplement the resources available to the publicly
financed services. Very small amounts, in comparison to
the total NHS budget, came from charitable sources,
together with some gifts in kind, such as equipment. But
in the wider field of caring rather than treatment the
contribution of charity was enormous but unquantified; it
probably ran into the small billions. It had been argued
that if the welfare state was doing what it ought to do,
charitable finance was irrelevant and outmoded. But
another view was that it was reasonable to top up what the
state was willing to do with charitable resources. How-
ever, if large amounts were involved, the state might well
start withdrawing its funds, thus undermining the whole
basis of the public contribution to health care. The same
argument could apply to the private sector of health care.
There was, of course, the great debate over whether the
private sector diminished or complemented the NHS. Mr
Harrison thought that if the private sector was to double,
the pressure to supply public money would diminish and
the total available resources would not necessarily in-
crease.
He did not think that within the present system of
public finance there was a way of matching the financial
decisions with the service itself and its consumers. There
were other ways of organising things. One method was
hypothecation, or earmarking of finance. That was the
best way of describing how the BBC was funded; a
specific licence fee went to that particular institution and
the particular fee was argued about in its own right. A
long time ago such a principle was adopted to finance
expenditure on roads and the road fund was set up.
However, the fund was soon absorbed into the exchequer
because the Treasury did not accept the principle of
earmarking. The same was the case for the so-called
health element in National Insurance. That just went into
the general pool of taxation and was, in no sense,
earmarked. In other countries there were hypothecated
taxes related to specific services such as education. As a
concept earmarking was a viable option. Its merit would
be that health expenditure would be debated separately
and would not be involved in the general debate about the
level of taxation in the economy as a whole.
Another possibility in trying to match the providers
and users of the resource was the local option. Local
government was supposed to have the merit of marrying
up local political preferences with what was spent so that
there could be divergencies from the national view. A
scheme could be sketched out that reverted somewhat and
put health in the local sphere. There could be a special
health tax, linked with the hypothecation argument. The
amount spent on health would vary with local preference
and it would tighten the link between those who made the
tax decisions, the tax-payers and the outcome. The
scheme might produce more or less but it would tend to
ease the strain of rationing that now had to take place
within the service itself. However, the present govern-
ment had made it clear that local authorities were not to
be allowed to set their own limits on expenditure.
Mr Harrison said that economics had come to be
known as the dismal science due to predictions that
resources would increase arithmetically and demands
geometrically. The various possibilities he had discussed
were not really practical and the constraint on resources,
with the very awkward decisions that had to be taken on
certain forms of care, would not disappear quickly. The
need for self-conscious rationing processes would grow
rather than diminish. Going back to his original point he
said that, with the present system, the overall priorities
were determined by the Cabinet, and other people then
had to work out the implications of those decisions.
Central government sent out through the DHSS various
messages as to how it wanted resources to be used. These
priority messages were not closely linked to the financial
system. With minor exceptions, the finance within the
NHS was not earmarked, so rationing decisions had to be
taken all down the line. He thought that if the pressure on
public finance was to continue to be as tight as it was now,
the principle of earmarking should start to apply within
the NHS itself and there should be earmarking of certain
funds for the care of the mentally ill or handicapped or for
other groups.
Mr Pace said he would go on from the theory as
outlined by Mr Harrison to the practical experience of the
last few years. Two things were under discussion; the
volume of resources to be spent on health care and the
value achieved from those resources. He thought the
NHS was suffering from culture shock at the moment,
coping with so much change in the approach to its
financing.
When he started work in the NHS it was virtually
inflation-proofed and looked for a steady growth of
between 1 and 3 per cent per annum. Life was more a
question of how to apply next year's increment, rather
than examining existing activity and costs. The 1975 oil
crisis had changed all that and had led to the introduction
of cash limits. These cash limits heralded the introduction
of real financial management into the NHS because until
then there had been no real discipline to planning, and a
change of approach was needed if value for money was to
be achieved. Cash limits had brought with them other
policy changes in the last 10 years, which had moved the
NHS from a rather insulated, inward-looking service into
a quasi-commercial one. For a start, cash limits now
contained a pre-set sum to cover inflation, of both pay
and prices, but in addition, the right to sell assets and to
apply for planning permission for the use of land had
been gained. Additionally, any income produced was
now retained, so all income from pay beds and charges
made for prescriptions and the like was retained within
the service. With cash limits came the ability to manage
cash flow, so if in one year a lump sum was needed to
produce a decent pay-back, the cash could be manipulat-
ed a little. Creditors would not like the fact that bills could
be slightly delayed in order to make cash available, but it
was now a tool for use.
So the NHS had moved from a situation pre-1975 of
Journal of the Royal College of Physicians of Ldndon Vol. 19 No. 3 July 1985
being fairly insulated to one which was almost into the
market-place. The trouble was that simultaneously with
this change many had started to question whether there
was enough money to carry out the task. He had listened
with interest to what Mr Harrison had said about the
possibility of producing more money from within the
service and if successful, the Treasury might say, 'Oh,
good, now we don't need to provide it'. He thought that
this was happening on the capital front already; looking at
the capital projections for the next few years there was the
suspicion that they would have been higher if it were not
for the successful sale of land, and though charges and
other methods of increasing resources might be successful
in the very local and the very short term, there was a
danger that they might become merely part of the
national package and then the same constraints would
apply to them.
Mr Pace thought it was a healthy sign that a start had
been made on looking at the way health services could be
financed, not just from public expenditure, but by en-
couraging the population to start making some of its own
provision. This was merely recognising that the state
could not provide everything. There had been something
of the order of a ?300,000,000 expansion of the private
health sector over the last six years in real terms. That
was new money coming into the system with people
putting it in from their own pockets, either through
personal expenditure or through insurance policies, or
maybe through their companies taking up executive
insurance policies and so on. But the effect in real terms
was about half a per cent real growth in the cash going
into health care. However,.there had to be differentiation
between the volume coming in and the value going out.
Mr Pace was interested in seeing the maximum amount
of money coming into health care, either in the private or
the public sector, in order to deal with the job in hand.
Charges, and the income from them, had always been a
two-edged sword because charges, once introduced into
the NHS, tended to be applied to a relatively small
section of the people using the service. Many people in
the wards and out-patient departments were in fact those
who would be given exemption from any charge that
might be introduced, and the moment there were exemp-
tions there was bureaucracy.
The growth of the health insurance market was uneven
nationally. Some work done had pointed to the fact that
the people who were covered by health insurance in the
UK tended to live in the better-off areas of the country,
and the better-off areas of the country were already those
that were seen under the national resource criteria as
being 'above target'. Thus the additional resources were
going into those regions that already had a fair amount of
resource. Whatever the method of raising resources, the
amount of money spent on health care would come back
to what the country could afford. Of course, the top level
of government had the fundamental option of deciding
what proportions of total expenditure went to individual
programmes. Probably, until the late 1970s, the NHS
had really done quite well at the expense of defence and
education but now the corner had been turned and health
was being caught by pressure from every angle.
Mr Pace accepted the view that the amount of money
would not increase at any great speed, either in the NHS
or in the private sector, or in the country as a whole.
What it really came down to in the end was managing
what was given with much greater efficiency and making
sure that the money was put into the places that actually
needed it.
The amount of money being passed down to regions by
government was enormous by anybody's standards. His
was a comparatively medium-range region yet spent
?650,000,000 a year and employed 50,000 people. No
ordinary sized company was in this league. An era was
beginning in which the money was taken at the very top
level and an attempt made to specify the businesses of the
NHS. The NHS was not one business but many different
businesses, some high level, high tech, high intensity
services and others very low level, the care and custody
sort of service. Additionally, there were problems in the
business where it interfaced with the social security and
social services. The NHS was having and would have
difficulty in trying to bridge the pressure on local author-
ity expenditure. The social security side, too, faced
complications in carrying out the government's policy of
moving people from inappropriate hospitalisation back
into the community. There was a fair degree of tension
between those particular guidelines and available re-
sources. The government would say that the local au-
thorities, within their total funds, could spend more on
dealing with these particular problems rather than on
other parts of their programmes.
The NHS was indeed a multi-faceted business. At
regional level, the one thing missing in the past was
clarity in the division of the ?650,000,000 received.
Which services should it be put into? What was expected
to be done with the money? How would its effectiveness
be judged? What were the units of work, the values, and
so on? At the moment measures of performance were
lacking. Splitting resources between businesses was deal-
ing with the management of change and in this context
consultants posed a problem. An average consultant
appointed in his late thirties or early forties could look
forward to 25 years of work in one specialty and probably
at one location. This was a major constraint on planning
change and a way of moving those consultants in their
fifties who were approaching retirement to posts in which
they would better serve the interests of the NHS had to be
found.
If splitting the total resources between 'businesses' was
a regional or national process, rationing between services
was very much a practical, down-the-line exercise. Mr
Pace was interested in government initiatives in this
rationing process. If the government provided
?10,000,000 for a specific purpose within a regional
programme already costing ?90,000,000, there was a
danger that the region, while spending the ?10,000,000 as
designated, would cut back on the rest of the programme
so that the total spent did not come up to the full amount
of ?100,000,000. It was probably true that central inter-
vention without a very careful monitoring of the total
expenditure was virtually sterile. If policy was not clearly
identified, the small-scale interventions, pump-priming
Journal of the Royal College of Physicians of London Vol. 19 No. 3 July 1985
though they might be, tended to run into the sand at some
point.
Mr Pace thought it curious that there was almost a
common view that the NHS was being cut. The strange
thing was that any cuts had not been significant at the
national level. The amount of money going into the NHS
had not been reduced significantly and yet there was a
fairly clear public view that the NHS was being attacked,
and all sorts of things were going wrong. He believed that
one main reason for this view was the increasing pressure
faced by the service. The demands were growing all the
time and therefore the press would always concentrate on
new treatments that were not being implemented, and
new pressures that were not being met. Additionally, the
culture of cuts was fuelled by the redistribution of re-
sources in the NHS, which meant very variable local
situations. Those in a Thames region facing resource
reduction or in a metropolitan district in a gaining region,
were all likely to see their real resources reduced. That
meant that a quarter of the NHS (four regions) was in a
perpetual state of giving money away to other parts of the
country. In the other ten regions, the teaching districts
were in the position of giving resources to the other
districts. It was not surprising that, although the total
sum of money was not being cut dramatically, the effects
on individual districts were serious. This was particularly
true of places like Guy's Hospital, and the coverage by
the press was a classic example of what tended to follow.
Probably only two real cuts had been made over the last
seven years; one was when VAT was under-funded and
moved from 8 per cent to 15 per cent in 1978, and the
other was in 1984 when 23 per cent of the total cost of the
wage award was met from savings in the service, thereby,
in real terms, cutting the cash. The service had not been
significantly cut; it was just facing pressures from a
change in the style of the service, changes in what the
medical profession could actually deliver and also redistri-
butional change.
Faced with the fact that the amount of money was
constrained, a government could only squeeze more value
out of what it provided. The whole of the Griffiths'
management initiative and everything else going on at the
moment should be seen in that light. How could a sleepy
service that had never really concentrated on the commer-
cial or industrial type of management be shaken up and
brought into an enviroment in which it could start to get
better value for money? Griffiths' view was that the NHS
had forgotten the consumer and that it was a service
industry; it was beginning to become slack and not give
full value for money. So even within the value-for-money
debate there were problems in microcosm. Faced with
pressure on resources, the NHS had started to move the
money that it should spend on equipment and buildings
into employing manpower to meet patient expectations
and so had found itself in the poor situation of staff
looking after more patients in a deteriorating environ-
ment. Unless this circle was broken at some stage health
authorities would finish up using far too high a percent-
age of their resources on manpower.
Mr Pace suspected that capital and revenue investment
was out of balance in the NHS. About 7 per cent of total
resources was being spent as capital, a 1:14 ratio of
capital to revenue that was probably too low. However,
the government had said that no more resources were
available and therefore there must be a question as to
whether the balance between revenue and capital was
right. If it was not corrected the practice of medicine
would continue in unsatisfactory conditions for the next
30 years. As well as the imbalance between capital and
revenue there was also a problem about the ratio of
manpower to non-manpower costs.
Proper control of manpower and its costs was a central
factor in an efficient NHS. How could this be achieved?
Testing costs through a tendering process was one possi-
bility. Many people were employed in delivering hotel-
type services. If they were delivering them economically a
tendering exercise should not, in theory, be a problem to
them. The profit element should enable them to beat off
any outside tenderer against a common specification.
During the present exercise there had been suspicions
that one or two companies had initially tendered low in
order to remove in-house opposition to any future tender
and certainly there was evidence that the second round of
tenders produced significant price increases. But as a
general principle, the services provided in the hotel
should be provided at the lowest, most efficient, cost; this
was something that had to be grappled with.
In addition to initiatives seeking better value for money
on the staff front, the government was expecting better
performance in the purchasing of supplies. The NHS was
an enormous purchaser, but not yet adept at using its
power in the market-place. Successive reports had said
that the service could and should do better. To be fair to
supplies staff, there were internal difficulties in the sense
that consultants and administrators at local level did not
want central imposition of purchasing procedures. The
consultant liked to have the piece of equipment he wanted
or the syringe he felt comfortable with and was very
reluctant to accept standard solutions which could be
cheaper. It would be for the greater good of all if these
particular issues were solved, the consequent savings
being made available for developments in care. The
considerable power of the NHS in the market ought to be
used.
By far the most significant factor in value for money
was productivity. It was necessary to achieve the best
return on each pound of the tax-payers' money received.
Productivity was a difficult term to use in relation to
patients. But why was it that some consultants kept their
patients in hospital for 14 days and others in the same
specialty kept them in for eight? This subject needed to be
grappled with more effectively. The figures in the Public
Expenditure White Paper showed a considerable drop in
the number of patient-days, but the number of cases dealt
with had significantly increased. Consultant numbers had
increased and productivity in relation to the number of
doctors, the number of cases and the number of patient-
days seemed to have reached a fair degree of equilibrium,
but it was uncertain whether the productivity of consult-
ants had increased or remained fairly stable.
The government had pursued other initiatives in the
search for value for money. Sir Derek Rayner had been
130 Journal of the Royal College of Physicians of London Vol. 19 No. 3 July 1985
brought in by the Prime Minister to look at Civil Service
efficiency and had later undertaken to examine the NHS
as well. It was decided that the NHS could benefit from
Rayner 'scrutinies' and a number had been undertaken,
with some success. One on- transport showed that the
services could be much improved. Another on residential
accommodation showed that far too much residential
accommodation was not being used properly. An adver-
tising scrutiny showed that too much was spent on
competition within the NHS for scarce staff. The latest
scrutiny on income systems suggested improvements in
debt collection; and this, associated with the apparent
failure to collect income related to consultants' private
practice, meant that less cash was available for services.
The most recent initiative was the restricted drug list. All
of these initiatives were designed to achieve better value
for money and were inevitable in the present financial
climate.
Mr Pace said that everyone was faced with enormous
pressure on resources. Government policy necessitated
increased expenditure on community-based services for
the mentally ill, the mentally handicapped and the eld-
erly. At some stage the community might have to decide
whether or not there was a place for people to serve that
community by making use of their extra leisure time and
their unemployed time and perhaps working for nothing.
Their ability to contribute to the high-technology side of
care was probably limited because highly trained staff
were needed in that area. The acute sector of the NHS
was being squeezed in order to move resources to com-
munity care where, in an ideal world perhaps, the
'family' should bear greater weight in looking after old
people. If facilities were located close enough to where the
community lived they could be given greater opportunity
to contribute. Unless alternative sources of resource could
be found, the only way of pursuing the government's
policy of care in the community would be to reduce
expenditure still more on the acute services, which much
of the population believed was what the NHS should be
providing at an improving level. There would never be
enough money to do everything and a much more
efficient job had to be done with what was available.
Discussion
Dr A. K. Thould said that value for money as judged by
an accountant was not the same thing as quality and
standard of care. He was concerned with the rapidly
ageing population around Truro where he worked. The
demand that the elderly made on the NHS increased
exponentially so that merely counting the number of
patients dealt with left out a very important part of the
equation which was the amount of input per patient. He
had looked at community problems for years and suspect-
ed that the real cost of community care was far higher
than usually thought. The costs of hospital care were
known. In his hospital the drug bill was only 1 per cent of
costs and it was the hotel costs that constituted the major
proportion and needed the most attention when it came to
savings.
Mr Pace said that, first of all, the planning had to be
right so that the money went to the place where it had
been decided to spend it. A lot of money got wasted
because it never got to the right unit. In terms of the unit,
getting value for that money depended on the consultants
and the managers discussing the inter-relationship be-
tween their services. One point about the elderly as high
consumers of health care was the need for psychogeriatric
care. The NHS was beginning to become a social service
as well as a health service and was trying to meet some of
the problems of local authorities.
Lord Ennals said that as Secretary of State from 1976-
79 he agreed with all that had been said about value for
money and the necessity of cash limits to force people to
fit within the constraints of a budget because there would
never be enough money to meet all demands on the
service. He questioned Mr Harrison's view that the
constraints would be the same whatever government was
in power. The different political parties did give different
priorities, in health as opposed to other aspects of their
policies, and in terms of different aspects of public
expenditure in relation to taxation. He also wanted to
point out the profound effect that rate-capping and the
abolition of metropolitan authorities might have on the
ability of local authorities to provide more community
care in order to relieve pressure on the NHS.
Mr Harrison replied that the scale of the problem in
terms of pressures from patients and from escalating costs
within the service was something that no government
could alter very much so that the scope for expressing
party political preferences was very limited. Lord Ennals'
comment on local authorities raised the question of
whether the total resources going to the NHS and social
services should be earmarked for particular services. The
overlap area between the NHS and local authorities was
growing in importance and very difficult to handle finan-
cially. In answer to Dr Thould he said that it would be a
mistake just to focus on the growing number of the
elderly. It had been calculated that this demographic
change would need an annual increase of half a per cent
in resources to maintain services. The pressure of de-
mand for services spread right across the population with
its increased expectations of what should be provided.
Dr D. G. Williams, speaking as a renal physician at
Guy's Hospital, said that the renal unit, in common with
others all over the world, had become much more efficient
and successful in renal transplantation. The patients were
now surviving into relatively old age, so that whereas ten
years ago his unit had a pool of 40 patients it now had 280
patients to be looked after, using the same number of
beds. As a consequence of increased efficiency the unit
was now in deep financial trouble. How could such
efficiency be penalised with the penalties now being
handed out?
Mr Pace replied that the government had said that
renal transplantation was a high priority service that it
wished to see expanded. In the very short term the extra
resources for this service could come from squeezing
money out of other services by making them more
efficient. But once efficiency had been achieved there was
no further saving to be made in this way and the pressures
were back. In the end the population at large had to
Journal of the Royal College of Physicians of London Vol. 19 No. 3 July 1985 131
decide whether they wished to spend 10X on one patient
in a particular specialty or IX on 10 patients treated for
other things.
Dr Tudor Hart took up Dr Williams' point about
being penalised for efficiency. In Glyncorrwg, South
Wales, he had looked after much the same people for 23
years, a population of 1,700. There was no residential
care.for mental defect or psychiatric illness, no long-term
geriatric care and they had not got any major drug
dependence. The percentage of males with no jobs (un-
employed or sick) was 48 per cent for ages 16 to 64 and 60
per cent for ages 14 to 16. The local economy was
devastated; in the Port Talbot area more than 50 per cent
of householders qualified for rate relief. Despite this he
said that Glyncorrwg was operating very efficiently.
Families looked after their own patients, though with the
number of children leaving the area this was becoming
more difficult. It should not be supposed that because a
community operated efficiently and quietly it could take a
further beating. There should be local budgeting for
community health services which should include primary
care services. That meant the end of independent con-
tractor status for GPs, as they could not be budget-
holders without some local accountability, which he
thought must come from the local population and to some
extent from local peer groups; no one would want
accountability to some central agency. Some new struc-
tures for democratic answerability were needed if doctors
were to think about their work more intelligently.
Mr Pace replied that he thought of community care in
terms of the community rather than of individual famil-
ies. The unemployed might be able to help in community
care as a free resource. He agreed that for better perform-
ance the resources should be put locally so that the people
were aware of them and could get better value from them.
However, those who wanted a resource never wanted to
lose the facilities of the other resources. There was always
a conflict between the urban centre of a region and its
rural communities, as well as conflicts between different
specialties and between consultants and GPs. These
indicated how diffuse problems became when dealing
with a number of agencies looking after local problems.
Dr J. Lister wanted to know whether the different
proportion of the gross national product spent on health
in Britain as compared to the USA indicated that the
NHS was really under-financed or that the USA was not
so efficient in delivering health care. If more was to be
spent on health it was necessary to indicate what was for
health care and what was for medical care.
Mr Harrison quoted the opinion recorded in The
Painful Prescription that the way limited funds had been
allocated in Britain was sensible. But the problem was the
loose connection between the providers of finance and the
users with their preferences. An economist was used to
people who wanted more money putting up plans that
detailed what would be done with that marginal incre-
ment of resource. The DHSS did not know what the
return at the margin was. It needed an information
system, accounting in the broad sense, before it could say
what would be gained from an extra sum or what would
be lost if that sum was not available.
Mr Pace added that more had been spent in the USA
on the environment of health care. In Britain some wise
decisions had been made in concentrating the high spe-
cialty centres and not replicating equipment throughout
the system. In America facilities could stand vacant
waiting for users to come along. In Britain there was
never an ounce of over-provision.
Sir Henry Yellowlees said that he had always been
mystified by the concept of a gross national product so
could not attempt to judge whether or not a fair propor-
tion had been allocated to health. It was better to talk
about the proportion of public expenditure which actually
rested with health and social services. The government
had planned for the year 1985/86 a total public expendi-
ture of ?130.21 billion, of which ?16.5 billion (12.5 per
cent) went to health and personal social services. In real
terms, against the base of the previous year, the planned
expenditure on health and social services was ?15.1
billion for 1985/86. This seemed to be a better way of )
expressing the size of the cake.
If, as had been suggested, earmarking of funds was a
way of making better use of what was available and made
better relationships between those who made the financial
decisions and those who had to live with them, it was
important that there was absolutely full consultation
between all those concerned. He was worried by what
seemed to him to be a deterioration in consultative i
processes.
Turning to medical manpower, Sir Henry asked if the
doctors made too many financial decisions and whether
the cost and size of medical manpower ought to be looked
at especially. For the first time ever the January 1985
figures showed a reduction in training grades of 1.2 per
cent and a rise in consultants of 2.3 per cent. After years
of striving for some such result he found it a consolation
that it had occurred a year after he had left the DHSS.
The junior grades had enthusiastically supported efforts
to get to grips with the problem of manpower; the BMA
and negotiating committees had been cautious but gradu-
al co-operators, the deans and universities had been v.
interested but mystified and the Royal Colleges had been
entirely courteous and extremely kindly in their total
obstruction.
Mr Pace said that the relative inflexibility in medical
manpower worried him when regions were planning
major resource shifts and changes in service between
different styles and locations. Other markets around the
world were more responsive to change than this one,
which had to be changed in a sensitive way. He would
expect government to be talking to consultants in a
constructive way about changes in where consultants
delivered their services. There was a lot of planning on
change which could be frustrated by the unwillingness of
consultants to accept and co-operate with it.
Adequacy of Care
Professor Rudolf Klein said that the level of expenditure
on health services in the UK had not been cut; in real
terms they had increased. However, levels of expenditure
were meaningless unless related to adequacy of health
132 Journal of the Royal College of Physicians of London Vol. 19 No. 3 July 1985
care. The basic question about the NHS, or indeed any
health system, was how to assess whether the health care
being provided was adequate. What bench marks or
? criteria should be used to evaluate 'adequacy'? He would
not answer that question for the simple reason that he was
unable to do so. But he would try to explore the various
dimensions of the concept of 'adequacy'.
The Royal Commission on the NHS had defined
, objectives for the health service, listing, among other
things:
1. To provide equality of entitlement to health services.
2. To provide a broad range of services of a high
standard.
3. To provide equality of access to these services.
4. To satisfy the reasonable expectations of their users.
These objectives raised as many questions as they an-
swered. They did not indicate how broad the range or
high the standard of the services should be or define what
was a reasonable expectation. The latest (1984) annual
report of the DHSS was of little help. The report stated
that the objective of the NHS was 'to provide effective
and appropriate treatment and care where necessary'.
But there was nothing about who should decide what was
1 > appropriate and what was necessary. If existing resource
constraints were taken as a limiting factor then the way
that priorities were defined could be questioned. If the
notion of adequate standards was accepted the ac-
ceptability of the constraints themselves could be ques-
tioned. Could constraints be compatible with what the
NHS should be trying to do by way of providing adequate
health care for everyone?
Professor Klein then proposed a framework for think-
ing about adequacy in the following terms?inputs, ac-
tivity, process and outcomes.
1
Inputs
In the sixties and early seventies it was fashionable to
consider adequacy in terms of inputs, i.e. so many beds,
so many doctors and so many community nurses, etc.
This assumed economic growth and that improved input
of resources improved the adequacy of care provided.
When the economic growth to underpin this concept did
not happen the popularity of the concept faded.
Y
Activity
This was a more recent fashion of thought that reflected
pessimism about economic growth and laid stress on the
numbers treated or on waiting lists for operations. The
more phrenetic the activity the more adequate the service,
appeared to be a conclusion.
Process
This gave a qualitative dimension to statistics. It also had
a technical dimension. The maternal death inquiry was
an example of finding out the adequacy of care. It was
about how individuals were treated rather than inputs.
One should know if the individual was treated with
proper respect and dignity as a human being.
Outcome
The emergent style of thinking defined adequacy in terms
of the impact of health services not only on individual
patients but also on a given population. It revolved
around the effects on the population and not on what
happened within the NHS. In considering outcome there
had to be a distinction between adequacy of treatment
and adequacy of care.
The adequacy of treatment posed familiar questions
about whether everything possible was being done to save
life and prevent disability. Was the quality of treatment
adequate to achieve the desired result and its quantity
sufficient to ensure that all who could benefit did so? Was
its distribution such that there was equality of opportuni-
ty (for equal needs) of actually getting it? Hence the
interest in monitoring the quality of medical treatment, in
achieving an equitable distribution of resources and in
analysing use by social class. Hence the controversies
about queues for specific procedures such as arthroplasty
and dialysis. Hence the big question of whether the
notion of adequacy was, like poverty, indefinitely expan-
dible in line with technological development. Did the
adequacy of a health system have to be defined by its
ability to meet the demand for all procedures that could
prolong life (heart transplant) or lessen disability (coron-
ary bypass surgery)? Professor Klein stressed that, be-
cause those were familiar questions, adequacy should be
thought of in terms not of medical treatment but of health
care provision. Care described what any health system
did to improve the quality of life of those who could not be
cured and to make inevitable disability more tolerable.
However, the definition of adequate care was more
difficult than that of adequacy of medical treatment,
which could be tested by the criterion of effectiveness. It
was difficult to judge what was an adequate environment
for the mentally handicapped or what was an adequate
supply of home aids and physiotherapy for the disabled.
Professor Klein asked who should define adequacy,
whether it meant the necessary, desirable or optimal in
any given situation, and whose definition should prevail,
that of health service producers or that of the health
service consumers. He considered that the concept of
adequacy was both a technical and a social one, involving
technical procedures and the environment in which these
procedures were carried out. The relationship between
the two involved value judgments whose implications
required analysis and debate. He wished to guard against
defining adequacy in terms of technical optimality, an
approach characteristic of American medicine. He want-
ed to settle for 'acceptable', somewhere between what was
necessary and what was desirable. Medical technology
was international but national incomes were not and
Britain needed to guard against an infinite technological-
ly-driven expansion of the definition of the 'desirable'.
Adequacy should not be defined exclusively in medical
terms, which might be the easiest to measure, for there
was always the danger that the measurable and dramatic
would drive out the desirable. Headline news was made
by those denied life-saving treatment but not by old ladies
who, for lack of aids, could not do housework or shop.
Journal of the Royal College of Physicians of London Vol. 19 No. 3 July 1985 133
Any definition of adequacy that left out the old ladies and
adopted an exclusively medical focus was likely to be
mischievous and misleading.
Discussion
Dr J. W. Todd said that for most patients who sought
advice for minor self-limiting illnesses and minor psychi-
atric disturbances the highest standard of medical care
was a visit to a GP who would listen to them and advise
but do no investigations, give no prescription and not
refer the patient to hospital. There were many unneces-
sary investigations done in hospital and unnecessary
admissions solely for investigation. There were also some
dubious hospital treatments such as cholecystectomy for
symptomless gall-stones and vast quantities of inappro-
priate chemotherapy and radiotherapy for cancer. Armies
of old patients repeatedly attended out-patients quite
unnecessarily. Doctors did have it in their power to make
enormous improvements in health care by getting rid of
this shocking waste.
Sir Kenneth Robinson wanted to emphasise one
aspect of adequacy in the NHS: its accessibility. In that
respect the NHS compared very well with the health
services of any country, however wealthy. There was
accessibility to hospital treatment for urgent cases, albeit
at the price of unacceptably long waiting lists for the non-
urgent. But the real jewel in the NHS was the accessibility
to primary care and the family doctor service. This should
never be forgotten.
Dr S. D. Horsley was worried that, if outcome
measurements were not developed soon, proxy financial
indicators would be used instead. The use of performance
indicators that had no output could lead to the absurdity
of it not mattering that many patients had died provided a
large number were going through the service. There had
to be some outcome measure that included the quality of
care element.
Dr H. E. Thomas said that he had been taught to
think of value as having two meanings, the value for
exchange and the value for use. He thought that the
financial speakers had not understood this difference.
Value for use in the medical context could only be
determined by one's peers. A system was needed to judge
the best value for use.
Professor Klein agreed that the performance indica-
tors used to measure many things did not measure the
adequacy of care. They might well distort perception of
what was happening by defining adequacy in terms of
activity. A lot of activity might not only be useless but
harmful. There was also the danger, seen in America, of
monitoring the quality of care provided by using process
criteria; e.g. it was assumed that the care of a patient was
better because he had 342 X-rays taken and not just one.
Partly this was defensive medicine but it also indicated a
confusion between technical optimality and adequacy. If
the two were equated, spending on the health service
would be doubled and untold suffering inflicted on the
patients.
He agreed with Sir Kenneth Robinson that the NHS
had a very good record of accessibility but he had begun
to wonder whether that might be measured by the ability
of the medical profession to damp down total demand. In
the issues of resource rationing and priorities, most of the
demands, certainly the expensive ones, were made by the
doctors. For years the rate of patient/general practitioner
consultations had remained constant at 4.2 a year. What
had persuaded the patients that this was an adequate rate
and did it have anything to do with the rather long wait in
the surgery?
k.
Moral and Ethical Problems
Canon G. R. Dunstan said he had brooded long over the
relevant literature on medical care and was aware of the
polemics of the resources debate, with one interest group
after another staking its claim against the cost of Trident.
He was also aware of the tedious and often spurious
counter-claims of high technology medicine versus hernia
operations or of one specialty (e.g. the renal lobby) >
against others within the allocated funds. He was aware of
the claims of disease in poverty-ridden countries of the
Third World against such things as special infertility units
in the UK and of the economies predicted of preventive
medicine, keeping people well as opposed to treating ?
them expensively when ill. He did not wish to discuss the
literature but instead proposed to recall seven foundation
maxims of medical care as a basis of claims and, if those
claims conflicted, he would leave others to adjust them.
The maxims, mostly from the past, would not be ex-
pressed in their original terms (still less in their original
languages), as it was necessary to wrest them from the >
thought forms of their times and express them in today's
terms.
His first maxim, established by Aristotle out of the
oldest and most essential exercise of a disciplined curios-
ity, embryology, was that the basis of human nature is
animal nature. Humans were biochemical products or
random genetic factors. His second maxim, also from
Aristotle, stated that imposed upon, or rather animated in
man's animal nature was a rational nature which enabled
man to speculate upon his animality and ultimately to
exercise a measure of control of it. But granted the
random factor in human genetic make-up and so its
ultimate unpredictability, understanding and explanation
could not guarantee total control. So good medicine stood
on observation, understanding and making experiments
(i.e. innovation) but although one could learn from the
past, the past could not be relied upon. To cut back on
research (unless it be cutting out the bad or unthought-
out research) was to cut at the root of medicine.
Human rationality also had a moral dimension, reason
exercising itself in moral judgment. One such judgment
found the random activity of biology fundamentally
unjust; it forbade the sentimentality of 'nature knows
best', except in certain restricted fields. It used words like
victim for some of nature's products, implying that they
ought not to be as they are and that their marred
conditions exercise on man a certain sort of moral claim.
Canon Dunstan's third maxim, from Aquinas out of
Aristotle, stated that man was a social being with affec-
tional and willed affinities to add to his biological species
134 Journal of the Royal College of Physicians of London Vol. 19 No. 3 July 1985
grouping. Man used this rationality to organise them into
polities or ways of living. Man had self-awareness, es-
pecially for pain, disadvantage and injustice, which gave
him a sympathy for the victims of biological injustice; he
found a moral imperative to look for remedies and had
the capacity to create and organise institutions of care.
The Jewish and Christian religions, to look no further,
added a motive to this moral imperative. Therefore
medicine was an art, grounded in a reasoned application
of curiosity and compassion and organised as a social
institution within diverse kinds of polity?cities, commu-
nities and now nations, all of various sorts. In moving
quickly from the embryo to the nation state Professor
Dunstan said that tension was to be expected and that the
ethics of priorities in medical care were the ethics of
tension.
His fourth maxim came from the Greeks and stated
that medicine had its ethics and so did politics. He
believed that the major confusions in the resources debate
stemmed from a confusion of these two, from the tempta-
tion to escape from the contingent tensions of medicine by
ignoring or wishing away the essential tensions of politics.
So primary duty had to be discovered and done within the
* contingently possible. A secondary duty might be to move
into the political realm to enlarge the economic basis of
possibility. It was important to recognise what was pri-
mary and what was secondary in these two ethical
obligations.
His fifth maxim was that medicine created polities of its
own, adapting variously to the local wider polities of the
times, be they the city state, the kingdom (ancient
Levantine or feudal European) or the modern nation
state, welfare, capitalist or socialist. Throughout history
doctors had varied in social status from slaves to the
confidants of kings and had had various systems of
rewards for good service and penalties for bad. But
doctors had always organised themselves into guilds,
fraternities, colleges and, latterly, into a profession. This
organisation entailed the corporate possession of knowl-
edge and skill and interest in social and material reward
and a corporate obligation to offer a service that was
ethically governed.
Within these ethics of medicine and politics the doctor
had to serve both rich and poor but might take from the
rich to pay for both. The basic injustice of biology should
not be compounded by economic injustice. Herein lay the
foundation of modern provisions for health care based on
mutual insurance, a service financed out of taxes with or
without voluntary contributions. Thus a maxim of medi-
cal ethics was to provide for those who did not or could
not generate wealth from the wealth of those who could.
4 This took medicine into the realms of politics to state and
maintain its claims by ethical means. Means were limit-
ed, as spending could not exceed production. Granted the
historical facts of a wide variety of economic relations
between medicine and the political community, Canon
Dunstan thought it would be the height of political
unwisdom to intrude a political dogma which made the
interplay of public and private funding as difficult as
possible.
His sixth maxim applied to both systems of ethics,
medical and political, and formulated the principle of
consent. Aquinas had used it in relation to surgical
intervention, but monastic communities had developed it
in relation to government by consent and then to rep-
resentative government. This concept was now somewhat
overwhelmed by loud voices that clamoured for conflict-
ing rights. However, the principle of consent was as
fundamental to the body politic (and its provision of
health care) as it was to the care of the body human. One
priority in medicine might be to come to grips with the
preoccupation with rights and forestall what might hap-
pen to medicine and society if an ethic built on consent
were to be replaced by an ideology of conflict.
His seventh maxim came from Hippocrates and stated
that it was unphysicianly to treat those for whom there
was no possibility of cure. This maxim was a gift to those
who gave a low priority to high-technological procedures.
But medical advances had not been achieved by holding
back and a balance had to be found between the new
untried and the established. The established could be
improved to some extent by learning from the untried,
provided that the learning be disciplined, controlled and
not 'free range'. How far a trial should go for any
individual patient was another question but there was
nothing unphysicianly about allowing men properly to
die.
These seven maxims had not offered clear-cut solutions
to anything but Canon Dunstan stressed that it was not
the moralist's job to provide the solutions to technical
problems, especially when those problems occurred in the
exercise of other men's professions, and that solutions
which did not pay attention to the maxims he had quoted
might not be worth very much or last very long.
Professor I. Kennedy said that he wanted to put
forward a logic flow, a series of ideas not unlike the
maxims set out by Canon Dunstan. As a lawyer he was
aware of the real world where solutions had to be reached.
His theme was from principle to practice and his brief
concerned the moral and ethical problems in the financ-
ing of medical care and in the limitations of the facilities
provided. Such terms as efficiency and cost containment
had been referred to as appropriate concepts to use in the
analysis of priorities. Efficiency merely meant 'productive
of the desired result' and gave no moral guidance. If we
wanted to be efficient we had to ask what we wanted to be
efficient about. Equally, talk of cost containment, the
argumentative flavour of the month in the USA, begged a
series of questions, in that decisions had already been
made about choices that had to be contained or not
contained. It was those decisions and choices that had to
be wrestled with. There was no simple way of avoiding
the analysis of the allocation of a scarce resource by
making it appear as a value-free exercise, pursuant to the
rules of economics. Economics was more a matter of
political philosophy than anything else, although it might
masquerade as no more than statistics. The question was
not could we, but should we, afford X or Y, under what
circumstances and with what arguments for and against.
The criteria for choice between X and Y were central and
had to be morally defensible.
There were three levels of problem. The first problem
Journal of the Royal College of Physicians of London Vol. 19 No. 3 July 1985 135
for the moral philosopher was how much of the total
resources of the nation-state should be allocated to health
and medical care as compared to other sectors using
money, time, human and material resources (such as
defence, education, transport). Once a sum had been
allocated to health and medical care, the second level of
problem was how to split up the allocation. The third
level, once funds had been split up, concerned who should
get the treatment, particularly if that treatment were, by
definition, scarce.
Professor Kennedy pointed out that to say that these
problems were not amenable to moral or any form of
rational analysis would imply that the criteria for de-
cision-making were not amenable to rational debate and
so the decision-makers could not be held accountable. As
such decisions were taken in the community and affected
everyone's livelihood, accountability seemed a very im-
portant factor but could not be discussed unless it was
agreed that the criteria for decision-making could be
analysed. There was a counter-desire in central and local
government to fudge the criteria in order to dissipate
responsibility and accountability so that no one was clear
as to why one unit was closed and another open. Alterna-
tively there were cries of professional freedom or territor-
iality that might or might not be rationally defensible. If
there were no stated reasons on which decisions were
made, the public surrendered power to the decision-
makers who would then be immune from accountability.
Therefore the question was what was the moral agenda on
which resources in society were allocated for health and
medical care, and who would set the agenda. Professor
Kennedy did not agree that the moral agenda for the
practice of medicine should be allocated only to those who
practised medicine or delivered health care. It could not
be any particular group who set the moral agenda. It was
necessary to be aware of the rhetoric of power which held
that those with certain technical knowledge were blessed
with moral superiority in making decisions. The moral
agenda for the allocation of scarce resources had to be set
within political institutions because this would guarantee
some political answerability from those with power.
The first principle on the moral agenda should be the
notion of justice, of behaving with a sense of what was
just. Other principles would include respect for life and
respect for people's dignity. Such principles should not
intrude too much into respect for freedom of choice and
the people's right to make up their own minds. There
were various theories as to what was just in a community
and Professor Kennedy agreed with Canon Dunstan's
view of the mutual care for those less able by those who
were more able which was the egalitarian view. This was
the notion of caring for each person as being of equal
moral worth (not factually equal) and equally entitled to
an opportunity to enjoy the sum total of society's re-
sources. Another, fashionable, view of justice was that
'What I have I should be entitled to hold', so that if the
individual could negotiate more medical care for himself
that was just. This was the theory of entitlement. The
theory of utilitarianism suggested that just decisions were
those made for the greatest good of the greatest number, a
cost-benefit analysis much beloved by some because it
appeared to be a factual exercise. This was not true
because it depended on both cost and benefit being
functions of the starting position.
Professor Kennedy thought that the egalitarian view of
justice should be our inspiration as it was claimed that we
lived by it. The question of whether the healthy should
look after alcoholics and drug users needed to be an-
swered. They should not be looked after if it was believed
that the well-off were not obliged to look after the less
well-off. Similarly, the view of how resources should be
allocated at all levels depended on the answer to that
question. As a matter of policy in the sharing out of
money to the NHS and other health care institutions the
aim should be to insure that each person had an equal
opportunity to enjoy health within the context of the sum
of society's resources and the need to do other things. For
instance, health might be improved by removing motor
cars but this would diminish very important deemed 7
needs such as the need to get around. But within this ?.
context the proportion of gross national product to be
allocated to health could be decided. While a great deal of I
GNP was allocated to medical care, a great deal of
economic energy was spent on anti-health production so
that the two sometimes cancelled out. It was not efficient >
to allocate money to medicine and also take it away,
thereby denying certain people the opportunity of equal
access to health care. The Black report gave examples of
what might be called injustices in the decisions taken as to
the amount of resources, human and material, allocated
by the tax-payer.
In dealing with the tensions that necessarily exist in the
competition for limited resources Professor Kennedy
offered a two-stage analysis. The first stage was to set up a
norm of ordinary care, to cater for what every urbanised
developed society could provide in health maintenance
and medical care. This ordinary care should be so
organised that everyone had equal access to it. It would
clearly be unfair if it was available only to those who could
pay for it or lived in the right place. Hence the organisa-
tion of revenue spending would be wrong unless justice
has been traded for some other notion of freedom (al-
though that would probably be unjust and wrong).
After the provision of ordinary care according to
international norms would come the provision of unusual
or special care. This type of care would make a greater
than usual demand on resources, and would have to be
set on a sliding scale. The choice between heart trans-
plants and intensive care units should not depend on arm-
twisting but on a considered moral analysis. The factors
should include the consequences of not providing the
treatment (the cost of continuing care if it was not
provided) and the effect of the treatment in terms of total
or partial recovery or degree in reduction of handicap.
There also had to be some research and development
potential. A check-list of priorities and preferences could
be built up which would have moral credibility and not
merely be the response to loud noise. Such priorities
would have to be drawn up after proper debate, which
would have the advantage of educating the public as to /
the limits of medicine. It would need centralised planning
and articulation of relevant criteria.
136 Journal of the Royal College of Physicians of London Vol. 19 No. 3 July 1985
w Professor Kennedy did not think that a rare resource
should be dissipated all over the place, although the
principle of equality of access required that the source
should be sited so that all people should be able to get to
it. Distribution of a resource was a problem. The decision
as to who should use it was another, as limitation of
resource meant that not everyone could be treated. The
traditional method was the queue, a rationing system
largely morally indefensible. A waiting list was not a
method of selection that respected life. A lottery system,
as used when polio vaccine was introduced, was unsatis-
factory for the same reason, as it depended on the
chronological fact of date of entry. Claims had been made
for the use of objective medical factors only in choosing
patients for renal dialysis but usually more than technical
1 criteria had come into such schemes. It was necessary to
work out what was morally defensible, not only for the
benefit of society, but also for the benefit of those who
practised medicine and who had to live with these hard
decisions each and every day.
i -<
Discussion
i % Answering Sir Douglas Black, Professor Kennedy said
that his lottery did not apply to clinical trials and their
ethics. He had applied the term only to the clear example
of where there were enough candidates for a treatment
but not enough resources. Patients could be admitted in
turn from a waiting list or chronology could be defeated
by pulling their names out of a hat. He did not think this
lottery was fairer. A better way had to be found of
s allocating a bed to one of ten candidates knowing that the
other nine might be harmed as a consequence of the
choice.
Taking this example Sir Raymond Hoffenberg asked
if it was fair that the decision was often left to one doctor.
Professor Kennedy replied that it was not fair to doctors
who were often in the position of being damned if they did
, and damned if they didn't. It was the obligation of those
who commented on these matters to develop the appro-
priate moral guidelines which would help rather than
confuse. He had argued that these matters were of such
complexity and importance that it behoved government
to set up a standing advisory committee to discuss the
issues one by one, taking appropriate evidence and then
issuing guidance papers which would attempt to offer the
four corners of moral propriety within which doctors were
entitled to act.
Dr I. Munro said that the legal ethicists with whom he
had conflict from time to time in his role as a journalist
would seek to lay down a code of ethical practice that was
too general. The analysis of individual instances of
resource allocation and of other ethical judgments in
medicine was a reasonable way of advancing people's
thought, particularly doctors' thought. Making a general
pattern based on rather vague concepts of right and
wrong led to difficulties. He, like Professor Kennedy, was
a pragmatist and would not favour an attempt to lay
down a code in very sweeping terms, but each decision
should be judged much more carefully than hitherto.
Professor Kennedy thought that the notion that one
could respond to individual cases as they occurred was
only tenable if the response was by reference to a set of
moral principles. Answers to specific individual problems
did not pop up from the problems themselves. They
popped up from the perception of how the problem fitted
within a moral taxonomy. Medical scientists, engineers
and everyone else had a taxonomy of analysis to indicate
the kind of problem. There was room for that in applied
moral philosopy. He agreed that it would be wrong to
think in terms so general that they did not particularly
direct the mind to anything. Facts had to be learned and
matters had to be talked about in the context of real life.
Categories could be built up, say of severely handicapped
neonates, which took account of morally relevant facts.
Any sensitive code would operate by examples and would
properly leave the doctor discretion in his choices, as it
was the right and responsibility of a professional to use his
professional discretion within the four corners of what
was indicated as morally tolerable.
Sir Raymond Hoffenberg quoted the case of two renal
physicians in Birmingham who had been faced with the
dilemma of having to turn down patients for renal dialysis
because they had exceeded their allocated budget and had
been told that if they persisted in spending more money
by taking on more patients they were depriving other
sectors of finance. In his view they had rightly argued: 'It
is not for me to make the decision about accepting or
refusing a patient. I cannot send Mr Jones away because I
haven't got the resources.'
Professor Kennedy replied that some claimed that a
doctor had a duty to serve the group as well as the
individual. By treating X here, he neglected the group
over there. Others said that the doctor could solve his
problem by addressing himself to his patients and his
patients alone. That did not resolve the problem, it solved
it by opting for one group instead of another. In the battle
for resources, decisions that should have been made and
enforced politically (to the extent that they could be), had
been allocated to be fought out by different lobbying
groups within the medical profession in a way whereby no
one benefited. He was persuaded that if, for good rea-
sonsj society had decided to spend a certain sum on renal
dialysis in a certain unit then that was the answer.
Canon Dunstan could not suggest any way out of the
dilemma; once the limit was reached that was the limit.
Those turned away could be provided with alternative
forms of care. They were not simply being rejected, some
appropriate management had to be found for them. Sir
Raymond Hoffenberg said that they were indeed being
rejected and deprived of live-saving treatment.
Miss J. Turner thought that doctors who had to turn
patients away had some sort of duty to the public to make
known what they had done. They could appeal to the
public more directly and with more public understanding
in the high-technology specialties than in the low. She
wondered whether it was really enough for doctors to
make difficult decisions and be quiet about them. She
wanted to hear of the duty to speak out. Canon Dunstan
said this came within his definition of secondary duty. To
enter into the realms of politics to secure needed resources
would be using the ethics of politics and not specifically
Journal of the Royal College of Physicians of London Vol. 19 No. 3 July 1985
medical ethics. Professor Kennedy agreed and added
that if a doctor thought the cut of the cake was improper
or morally wrong he was entitled to enter the debate, his
only special qualification being his great technical and
specific knowledge but with no greater standing on the
moral and political decisions on resource allocation.
Dr A. K. Thould thought there would be little in the
way of resolution of problems by public debate on
television. The emotive problems would be debated, as
they made good news, but the equally important non-
emotive problems would not, as they did not have news
value. It was of equal importance that those needing renal
dialysis should get it and that the disabled should get the
required occupational therapy. Society normally resolved
problems by putting them in the market-place. If there
was a need for X, someone would manufacture it and
those in need would buy it at a price. To be fair to those
who required it, the NHS had been taken out of the
market-place, which had produced enormous problems of
choice. In the last resort the choices had to be made by
politicians, who should have the courage to have a public
debate so that people who used the services could say
what they wanted.
Dr T. Brewin said that decision theory could be used
to look at both public and individual decision-making.
The application of this theory in medicine, to both
individual and public policies, often resulted in finding
out that there was still a problem. However, the process
itself, whether done in private or in public, illuminated
the problems and might dispel anxiety.
Canon Dunstan said that he was all for applying in
appropriate spheres a theory of decision provided it was
validated and workable. He would not let himself be
bound by it absolutely as some day there would be a case
to which the theory did not apply.
Miss K. Whitehorn said Professor Kennedy had been
provoked to talk of the doctor as a doctor and as a political
animal. She wanted to know about the patient as a patient
and as a political animal. The doctor, in turning down a
patient for dialysis, might think that he would be more
comfortable with the explanation that his condition was
not suitable for dialysis rather than being told: 'Sorry, old
chap, we haven't got the resources'. On the other hand,
the shroud waved most effectively was one's own. Might
not the doctor consider it his duty to say: 'We aren't
dialysing you because we haven't got the resources so go
and tell the local paper and maybe we can whip up some
support'. She wanted some thoughts on this doctor's
extra dilemma.
Canon Dunstan knew what the doctor must not do; he
must not use his patient as a political pawn in any way
which might be to the patient's disadvantage. After that it
was a matter of the doctor's judgment of his patient's
capacity to enter with him into a consensual agreement on
the course to be followed. This was consistent with the
principle that the patient was also a moral agent.
Professor Kennedy agreed, and added that the doc-
tor's duty was first and foremost to his patient. What was
in the best interest of the patient was usually defined by
the patient and therefore if the patient became a willing
partner in the doctor's desire to point out some political
difficulty, that might gratify the patient and be an act in
his best interest. To use a patient as a means to an end J
would be inappropriate behaviour.
Dr T. Brewin felt that there should be public debate \
on the big decisions on priorities, on how much should be ^
spent on health and what sort of health. The minor
tactical rationing decisions of day-to-day care were taken (
best by an experienced doctor who had learnt from his
mistakes. He would not make better decisions if there was
a committee at his elbow.
Professor Kennedy made it clear that he did not \
advocate that decisions should be taken by committees. (
He repeated that he wanted doctors to exercise proper
discretion within the context of what was deemed morally
tolerable by the community. The determination of what
was morally tolerable was not at the behest of the medical
or any other profession. It might be that some form of \
committee could work out what was appropriate in the
case of resource rationing and the doctor would be
obliged morally to live within that framework. ,
Canon Dunstan said that over such a wide range of
decisions it was necessary to work out means of decision ^
relevant to the locus of authority for that decision.
Whatever the consultative processes and committees con- J,
cerned with the allocation of resources, in the end the \
minister would decide. Similarly the clinician, whatever
advice he took, had to decide about his patient. No one
would advocate one vast principal consultation by com-
mittee for such a wide range of potential decisions.
Professor Kennedy thought it was begging the question to
talk of the locus of authority. The doctor had the decision-
making capacity because he and no one else had to make
the decision. What mattered was the moral context in
which his decision was made.
How Do We Manage?
Sir Douglas Black said that, like the other speakers, he
had no intention of answering questions but would
embroider on them, beginning with a double tribute to
Dr David Owen. Dr Owen had said very plainly that
need could never be really met even by the utmost )
superfluity of resources. There would never be a complete
equation between need, which in theory should evoke
demand, that in turn would lead to supply. Dr Owen also
had the bright idea of finding out what were the main
burdens on the NHS and then dividing the transferred
sums to the MRC proportionally to the main burdens. Sir
Douglas and Mr David Pole, then economic adviser to
the Department of Health and Social Security, had been
given the task of measuring these burdens. First they
looked at the International Nomenclature of Disease with
its 900-1,000 items. They thought that categorisation in
these terms would not be useful for anyone, let alone
those commissioning programmes for the MRC. Instead
they made groups of about 50 items and then devised five
indices of burden on the NHS?in-patient days, out-
patient referrals, visits to GPs, sickness benefit and loss of
expectation of life. The use of loss of life expectancy
rather than mortality rates loaded the index in favour of
children, which seemed sensible and fair.
138 Journal of the Royal College of Physicians of London Vol. 19 No. 3 July 1985
In terms of in-patients (Table 1) more than half the
urden on the NHS was accounted for by mental disease
and handicap. But the burden in terms of out-patients
(Table 2) was quite different, with a much more varied
picture and neurological disorders at the top of the list.
Table 1. Burden on the NHS. In-patient days [1].
% of total burden
Mental illness
Mental handicap
Cerebrovascular disease
31.31
15.19
4.36
Table 2. Burden on the NHS. Out-patient referrals [!]?
% of total burden
9.82
7.84
6.87
6.72
5.90
5 50
Urogenital disorders '
a/f ^_i j: i j.yb
Neurological
Accident and suicide
Bone and joint (not arthritis)
Digestive disorders
Skin disorders
Mental disorders
Arthritis and rheumatism
3.72
The burden indicated by visits to GPs showed respirat-
ory infections at the top of the list (Table 3). Indeed, each
index gave a different set of priorities. The precise
problem of what weighting should be given to each
priority had been evaded by all politicians. Table 4
showed a partial index in that it related only to those
employed who were absent from work through sickness.
Table 3. Burden on the NHS. GP consultations [1].
Respiratory infections
Mental disorders
Bronchitis and asthma
Skin diseases
Accidents and suicide
' y Digestive disorders
Arthritis and rheumatism
Heart disease
Other bone and joint disease
% of total burden
16.03
7.73
5.07
4.84
4.63
4.05
3.99
3.06
2.79
Table 4. Burden on the NHS. Days of sickness benefit [1].
Bronchitis and asthma
Mental disease
Accidents and suicide
Arthritis and rheumatism
Respiratory infections
Ischaemic heart disease
Digestive disorders
% of total burden
11.46
9.55
8.81
7.22
7.17
5.73
5.73
The importance of mental disorder and respiratory dis-
ease was clear. Loss of life expectancy (Table 5) con-
cerned only three conditions, with arterial disease
accounting for almost a third of the loss. As ischaemic
heart disease came late in life it was under-estimated in
this table, whereas diseases like leukaemia that were
prominent in childhood were over-estimated. By taking a
simple average of the five indices some idea of important
conditions in terms of burden could be found (Table 6).
Table 5. Burden on the NHS. Mortality (loss of life expectancy)
[!]?
% of total burden
Ischaemic heart disease 21.51
Neoplasms 20.63
Cerebrovascular diseases 10.88
Table 6. Burden on the NHS. Simple average of previous
indices [1].
Mental illness and handicap
Respiratory diseases
Ischaemic heart disease
Bone and joint diseases
Accidents and suicide
Neoplasms
Digestive disorders
Neurological disorders
Cerebrovascular disease
Skin disease
Urogenital disease
Total
% of total burden
13.60
13.47
6.59
6.38
6.25
6.08
4.56
4.11
3.74
2.55
2.31
69.64
Sir Douglas felt that such an exercise was more relevant
to service provision than to the allocation of money for
research and that research on a group of diseases depend-
ed more on appropriateness and availability of people
with the necessary interest. As a pragmatist he wanted to
put resources into things that saved life or demonstrably
improved the quality of life. In terms of outcome, re-
sources deployed in this way might be better than putting
them into the so-called Cinderella diseases, although they
also needed resources.
Of other indices that formed a possible approach to
management would be one based on the quality of life. By
that criterion hip replacement would come way above
most life-saving measures. The worst possible way of
determining priorities was to listen to pressure groups in
which the still small voice of reason could not be heard.
But the concept of burden was inadequate as shown by
the fact that deafness, which severely impairs the quality
of life, gave a burden of about 0.5 per cent; yet Mr Jack
Ashley managed to elevate research into deafness to a top
priority.
Turning to the role of management Sir Douglas
thought that such things as the hotel side of hospitals and
Journal of the Royal College of Physicians of London Vol. 19 No. 3 July 1985
139
appointment systems were susceptible to improvement by
management but that the worrying point as to whether in
the NHS things were being done that need not be done
and others that should be done were being left undone
could not be 'managed' away. Such items were firmly
based on professional skills.
Sir Douglas said that the NHS and medicine in general
were for patients and not to provide employment for
doctors and managers. The term patient had to be
widened from the person who came to the doctor who
then did his utmost for him to the potential patient for
whom disease could be prevented. There should be no
diminution of the emphasis on prevention, which needed
additional resources, not resources taken from the acute
services. It was also important to ensure that doctors were
adequately trained to take the sort of decisions discussed
in the conference. It was equally important that doctors,
nurses and all who worked in the NHS should be caring
people. He did not think that the ways of ensuring this
were fully known but they had to be found.
Sir Douglas was sure that the health service had a great
future, but that future was dependent on the. advance-
ment of knowledge and nothing in the narrow pursuit of
economy should be done that threatened either the
training of future doctors or the advance'4!of medical
knowledge.
Mr R. Nicholls said that he wanted to emphasise the
need for sound management in the NHS and to give some
examples of managerial activity, largely from the regional
point of view. Management had only recently become a
respectable word in the NHS vocabulary and there was
some way to go before a management culture was
developed in the service. Given that management was
about achieving results from limited resources, it was
clear that a lot of it had been going on in the NHS. Some
would say that management was doing well. There were
high and rising patient activities in the health system
which took one of the lower proportions of GNP of any
country. The score on the few available health outcomes
was also good. Surveys showed a high level of satisfaction
with the services provided and the NHS had shown
remarkable resilience and productivity despite a series of
crises, some of them self-inflicted. Yet the politicians, the
media and some workers in the NHS were extremely
critical of the failures and inadequacies of the service.
There were real problems such as barriers and delays to
access, wastage of some key resources and a rather fixed
use of medical manpower. Perhaps consultants, like
general managers, should have short-term contracts. In
particular the NHS had been criticised for its slowness in
implementing plans and priorities which had been set out
by the elected government that continued to fund 90 per
cent of the resources. There was also the criticism,
highlighted in the Griffiths' report, of NHS attitudes to
and communications with its customers.
He underlined the need for good management by
showing the tendency of all Western health care systems
to absorb ever-increasing resources yet continue an ap-
parent decline. The demographic trends in his region
illustrated this. There would, in the next ten years, be a
spectacular rise in the number of those over 75 years old
and an apparent increase in those aged up to four years.
These two groups were the biggest users of the health
services, particularly the acute services. The overall
demand for acute services was expected to rise in his
region by over 10 per cent in the next decade. The use of
facilities by the elderly was expected to rise by 15 per
cent. This was against an expected resource gain of 1.5
per cent p.a. This did not take into account what might
happen to pay settlements or demands from the rise in
medical technology and the ability to do things or the
demands from the customers and other services that
might be called priority. Clearly there was a shortfall and
the region had to consider what could be obtained by cost
improvement programmes. These, traditionally, had
been about raising efficiency, and saving on heat and
hotel services. These savings had been running in the
region, as elsewhere, at about 0.5 per cent p.a. More
important were transfers to the community, which meant
that cost improvement involved a change in priorities. If
the objective was to move resources to the community, its
achievement could be counted as cost improvement.
There was also the increasing productivity in the acute
services and the region's declared priority for the Cinder-
ella services and prevention. He thought that manage-
ment needed to make targets if anything was to happen.
He suspected that management of the NHS had been
rather like the weather was to Mark Twain, everybody
talked about it but not a lot was done about it, at least at
the corporate level. Individual clinicians, used to manag-
ing their resources, might think the debate to be rather
old hat, but resources were now being looked at on a
district, regional and even national basis. There had been
many central initiatives trying to cope with choosing
between competing claims for the limited resources avail-
able. Until recently the emphasis had been too much on
structural reform. There had been central initiatives
designed to improve the efficiency of the service, includ-
ing the 1982 system of reviews, first by ministers of the
regions, then by regions of their districts and, increasing-
ly, by districts of their units. This was an important
logical management initiative. There was no point in
planning a priority system if there was not a way of
reviewing achievements at all levels. Health authorities
had had cash limits for some time and they were now
accompanied by annual manpower targets. These initia-
tives had been designed to put the NHS under the DHSS
microscope but they suffered from two major weaknesses.
First, they had focused too narrowly on efficiency, divert-
ing managerial effort away from broader issues like
quality, effectiveness and priority. Second, they had
undervalued the considerable achievements of the NHS
and created the impression that all its problems could be
solved by better management. Even the Griffiths' report
had been seen in this light initially.
Mr Nicholls considered that when the rather ghastly
process of appointing general managers was over, the
concept of general management would allow the NHS to
address more effectively some of the issues that faced it.
Two key recommendations by Griffiths were the estab-
lishment of a supervisory board with the ministers and the
heads of the professions at the DHSS and the setting up of
140 Journal of the Royal College of Physicians of London Vol. 19 No. 3 July 1985
the NHS management board. These should give a sense
of strategic purpose within the NHS, in terms of the
proper role of the health care system and targets to be
achieved in the next decade. The government was a
signatory to WHO's Health for All 2000 but its targets
had not been widely promulgated in the service. The
central requisites also gave the opportunity for selectivity
and more certainty in operational planning for one or two
? years ahead. They should help the management of the
service to be somewhat distanced from the inevitable
oscillations of politics. Politics had a vital place in devel-
p ?ping criteria for priority decisions and for setting broad
policy objectives, but management needed freedom to get
on and implement.
At regional, district and unit level Griffiths had rec-
ommended the development of a general management
culture throughout the service, a commitment to corpo-
rate objectives, the accountability of individuals for
achieving results and the development of information and
management budget systems to involve clinicians more
* - closely in management; the use of resources was to be
maximised, with responsibility placed on individuals at
each level for planning implementation and control. If
, properly developed, general management could bring
about delegation of decision-making and give a much
needed sense of direction and corporate purpose to the
whole organisation.
General management would not happen overnight and
would need considerable effort and sensitivity from all
those involved. The NHS's management's main task was
to make hard choices about using scarce resources in such
a way that clinicians and the public at large had confi-
dence in the way these were made.
It was clear from the review system that the Secretary
of State held regions to be accountable for the overall
management of the health service throughout their terri-
tories and for implementation of agreed plans and priori-
ties. Given that regions had to work largely through
districts, which were separate statutory accounting and
employing authorities, and through consultants whose
contracts they held but whose work they could not easily
monitor, there was plenty of room for tension and
different operational models. In addition to their tradi-
tional role of producing strategic planning guidelines and
sharing out resources between districts, regions were now
setting specific targets for districts to achieve in the use of
resources and within agreed time-scales. Regions were
also implementing plans by a variety of methods, includ-
ing specific agreements with districts on tasks, and help-
ing to solve problems which might delay implementation.
Regional powers were being used in a more purposeful
way.
Mr Nicholls recalled the remarks on the earmarking of
funds and said that at central or even regional level,
earmarking had a pretty dismal track record. Earmarking
was not comfortable for politicians, it raised too many
questions about the criteria for priorities. He thought that
the creative use of available resources was the essence of
management. His region had found that, for the mentally
handicapped, it could provide better care for less money.
Much of what had been spent was tied up in overheads
and hotel services. By transferring to community care
with support for the carers, advantage could be taken of
other fiscal measures, notably the payment through the
other branch of the DHSS of social security for people
living in their own or group homes in the community.
Another use of resource was the sale of lands, which
would release millions of pounds.
In dealing with the projected 10 per cent rise in
demand over the next decade due to demographic
changes, his region had asked its districts to see how they
could achieve an annual cost improvement of 2 per cent
over the decade. This was a tall order but there were
improvements in performance to be made. Reduction of
turnover interval to two days and providing day places
would achieve nearly a 5 per cent increase in productiv-
ity. Things were not quite so simple and consultants
working in the districts were being asked to look at the
performance and appropriateness of particular treat-
ments, admissions and use of out-patient departments.
There was also scope for saving by improving communi-
cations using the new technology for computed and
automated offices, scans by telephone and videos for staff
training and health education.
Lastly Mr Nicholls remarked on the appointment of
clinicians as general managers, particularly at unit level.
The commitment to management would be not less than
seven sessions a week and he thought that few clinicians
would wish to abandon such a high proportion of their
clinical work. In most cases clinicians were wanted as
clinicians, although involved in management through
their professional advisory machinery, as accountable for
the resources they commit and, in some instances, as
budget-holders for clinical departments. What was im-
portant was that all doctors should be helped to under-
stand more about the organisation and its costs. First
exposure to management should come at the undergrad-
uate stage and certainly in the early postgraduate years.
Dr June Crown said she would talk about the approach
to problems rather than how to solve them, as she did not
think satisfactory solutions had been achieved. She want-
ed to put into concrete terms the effects of limited
resources within a health district, to set out the choices
that had to be made and describe their effects on patient
care.
The Health District of Bloomsbury was a very mixed
area of London. It contained five main-line railway
stations and included the College of Physicians and the
slums around King's Cross. There were many homeless,
a large ethnic minority of Bengalis, Cypriots and Chi-
nese, a large daytime population of commuters and many
visitors. The local residents included the highest propor-
tion in the country of elderly people living alone. The
District had five predecessor authorities; two districts,
each with a District General Hospital that was a distin-
guished undergraduate teaching hospital, and three
groups of postgraduate hospitals. Among the various
supporting hospitals were two that differed from the rest
in that their future had not been settled through the
normal planning procedure. The Elizabeth Garrett An-
derson Hospital had been rebuilt after direct ministerial
intervention and provided gynaecological services by
Journal of the Royal College of Physicians of London Vol. 19 No. 3 July 1985
141
women doctors. The Royal Homeopathic Hospital
housed homeopathy as well as some other clinical activi-
ties.
Bloomsbury was obviously not a 'typical' district but
the principles of determining priorities were the same for
all districts, whether they were resource gainers or loacis.
All districts had to provide care for local residents and
take account of demographic change. All had to ensure
that services not available locally were available and
accessible somewhere for their residents when they need-
ed them. All had to try increasingly to take account of
outcome measures in the planning of services.
There could be little doubt about the value (outcome)
of vaccination and immunisation programmes for chil-
dren. Questions raised about cervical cytology pro-
grammes in relation to their effectiveness were being
taken account of in future developments. The very
serious questions about some cancer therapies were still to
be addressed. It was necessary to have the courage to stop
services that did not adequately meet clinical needs in
order to make space for the development and innovation
so essential in medicine.
Bloomsbury District's present annual revenue was
about ?110,000,000. The District was well above its
Resource Allocation Working Party (RAWP) target and
by 1993, ?14.1 million had to be provided for RAWP
distribution. Much of this saving ought to be achieved by
redistribution of services and a considerable reduction in
the number of sites of operation. This would have clinical
advantages in that work done in the unidiscipline hospi-
tals would be transferred to sites with a full range of
diagnostic and therapeutic services. To achieve this
would require a considerable capital expenditure on
upgrading buildings for, like many inner-city districts,
the more modern buildings in Bloosmbury were over half
a century old and none had had the necessary modernisa-
tion required for the adequate practice of twentieth
century medicine. Most of the money for this work would
have to come out of the district's revenue budget. How-
ever, the district budget included various components
(regional specialties and postgraduate hospitals) that were
protected and so limited flexibility in achieving savings.
In such a difficult situation the health authority respon-
sible for the district's services had been clear and open
about its view of priorities. It intended to:
1. Provide first class services for its local residents. In
common with many other inner city districts, Blooms-
bury's community health services suffered from many
inadequacies as described in the Acheson Report (1981).
Priority services which worked to a catchment area and
by definition served local people (geriatric, mental illness
and handicap) had not been well developed and required
more investment.
2. To sustain the regional and supra-regional services
offered in the district's hospitals. Some of these, such as
cardiac surgery and radiotherapy, were formally recog-
nised and had protected funding. A reduction in the level
of these services would result in a reduction in the level of
district funding.
3. To continue to support the teaching of health profes-
sionals?medical, nursing and paramedical students?an
important part of undergraduate and postgraduate hospi-
tal activity. It was necessary to provide teaching staff and
patient services that were satisfactory in range and qual-
ity. The district's responsibilities in this area with regard
to medical and dental students were recognised by an
adjustment to the RAWP target of the Service Increment
for Teaching (SIFT).
4. To improve the environment in which patients were
treated and in which staff had to work. This meant the
improvement and modernisation of buildings.
During the first two years of the Bloomsbury District's
existence the revenue budget had remained stationary,
which meant a reduction of funding in real terms of about
5 per cent (due to inflation). Nevertheless, the authority
had decided to transfer ?500,000 annually (slightly less
than half a per cent of the revenue budget) into priority
services. This was an arbitrary sum but, despite problems
in finding sites for new health services in Bloomsbury,
innovative schemes could be implemented, each being
subject to evaluation to demonstrate the extent to which
the project met the objective.
Revenue savings were met in part by increased efficien-
cy and in part by reductions in general acute services.
Such reductions were consistent with the authority's
declared priorities because a significant proportion of the
patients treated in some of the general acute specialties
were coming into Bloomsbury for treatment which could
and should have been provided for them locally. It was
not thought that Bloomsbury should provide curettage for
ladies from St Albans or grommets for the ears of children
from Chelmsford.
Between April 1982 and January 1985 the number of
beds for local acute specialties (excluding those in the
postgraduate hospitals) in Bloomsbury was reduced from
1,059 to 859, a loss of 200 beds. During that period the
management of patient care was improved so that the
work load was little reduced (from 12,609 deaths and
discharges in the second quarter of 1982 to 12,464 in the
last quarter of 1984).
The authority had also agreed to withdraw acute
services from two supporting hospitals and concentrate
them on the University College and Middlesex Hospital
sites. By April 1985 there would be a further reduction to
714 acute beds in the district. This concentration of acute
services should lead to further efficiency and would have
the advantage of making the full facilities of the main
hospitals available to more of the patients who needed
them.
The authority's declared service priorities had been
widely supported within the district. The choice of service
changes had not been painless but had been logical and
reasonable; it had been possible to reorganise undergrad-
uate teaching to fit in with the changes.
The end of resource reduction was not near; there was
a long way to go to meet the RAWP target and much
other work needed support in the district. As opportuni-
ties for more saving through measures of efficiency
became progressively harder to achieve, it was clear that
further reductions in services were inevitable if the au-
thority was to keep within its cash limits. The problems
were confounded by the fact that planning was increas-
142 Journal of the Royal College of Physicians of London Vol. 19 No. 3 July 1985
ingly finance-led and it was important to identify changes
that could be implemented quickly and easily.
The authority had to address itself to the priorities of
the following problems:
1. Should it abandon the protection of the priority
services for local people? This would mean even longer
waits for the elderly to receive proper support in tteir
homes and longer waits for residential care for the
* demented elderly and for any locally based services for the
mentally handicapped.
2. Alternatively, should it abandon certain specialties so
as to preserve the rest? This path had already been
embarked upon and it was a question of how far it could
be followed before the teaching function and quality of
clinical services of other specialties were seriously preju-
diced. Dispensing with regional specialties that had pro-
tected funding might constitute an 'own goal' in trying to
meet financial targets.
3. Should the use of revenue for capital works be
stopped? This, as an effort to maintain services, had
obvious short-term attractions but meant that long-term
targets would be even more difficult to attain. Premises
would become even more out of date and depressing.
Moreover, it would not yield sufficient savings and would
have to be coupled with further reductions in services.
4. Should the reduction of general acute services be
continued? This would appear to be an attractive choice
and consistent with the district's declared aims. However,
the point would soon be reached when the viability of
certain highly specialised services would be threatened.
These services went under the banner of 'general' medi-
cine or surgery but were really regional or supra-regional
services, such as the investigation and treatment of
children with growth problems, specialist gynaecological
endocrinology and gastroenterology. If these services,
receiving patients from great distances, disappeared from
? Bloomsbury they were not available elsewhere. Careful
evaluation of these services had been carried out and
outcome measures did exist to demonstrate their efficien-
cy.
Dr Crown said that as a Community Physician she
could attempt to measure the need for the various
services, relate that need to demographic change and
population projections and then try to calculate the
proper size and balance of future services. As a prac-
titioner in a shortage specialty she had to identify her own
priorities. It was difficult to justify prolonged detailed
work on such issues in the district when history had
shown that decisions would be made on a political rather
than on an epidemiological basis and that financial
imperatives would prevail. As District Medical Officer
with responsibility for medical manpower she had to look
at the implications of the choices for medical staffing. To
reach financial targets would mean considerable cuts in
medical staff budgets. Further choices came into this,
such as should the consultant grade be reduced (which
could not be done by natural wastage) or should training
posts be eliminated, although these were often part of
rotation schemes that were highly regarded as providing a
balance of academically orientated and apprenticeship
training.
However, Dr Crown said that as a community physi-
cian she had considerable reservations about the RAWP
formula that was one of the bases of current problems. No
voice had been raised in Bloomsbury against the principle
of RAWP despite its harsh effects on clinicians. Everyone
supported the development of services in peripheral dis-
tricts and acknowledged that Bloomsbury was over-
funded and that considerable savings could be made. The
RAWP formula had been introduced in 1975 and since
then there had been great advances in information tech-
nology. It would now be possible to consider amending
the formula to take account of cross-boundary flows and
their reimbursement. Under the present arrangements a
child who came from outside Bloomsbury to receive very
expensive growth hormone therapy was credited to the
district at the average cost of a general hospital paediatric
case. The detailed information available from the 1981
census was of particular relevance to health care in inner
cities and could be used to incorporate deprivation
weightings into the RAWP formula. The application of
RAWP was a positive disincentive to the development of
community and out-patient care. In Bloomsbury some
major departments, like rheumatology, gastroenterology
and genito-urinary medicine, treated large numbers of
patients but had relatively few in-patients.
There was also the apparent total dislocation of
RAWP-losing movements of money from RAWP-gain-
ing developments of service, and the inconsistency of
RAWP losses in inner cities which were at the same time
receiving money from government departments through
'inner city partnership' and other schemes. The teaching
and other RAWP-losing districts were facing a downward
spiral (Fig. 1). As revenue was reduced, services were cut
and so cross-boundary flow diminished, which lowered
the RAWP target. Then more service reductions became
necessary, reducing teaching capacity. Students would
then have to be taught in other districts so SIFT would be
transferred, leading to further reduction in the RAWP
target. It meant constantly chasing receding targets.
The priorities being defined and preserved in Blooms-
bury would inevitably lead to some service losses. The_
special services, although representing the interests of the
doctors concerned, had developed in response to patients'
needs. It was essential that the medical profession and the
Royal Colleges should participate in decisions on priori-
ties in clinical services. They should aim to ensure that
the decisions taken were robust and did not destroy
services for which there was a clear need and demonstra-
ble value, and which would be difficult to replace.
Discussion
Dr J. W. Todd, commenting on the phrase 'finite
resources, infinite demand' pointed out that the one and
only demand the man in the street could make was to see
his GP and get his advice. Everything beyond that was
demanded or underwritten by some doctor. He instanced
a man with chest pain investigated with ECGs and
coronary arteriography only to be passed to the orthopae-
dic surgeon to exclude orthopaedic causes for the pain
and then to the neurologist to exclude neurological causes
Journal of the Royal College of Physicians of London Vol. 19 No. 3 Tuly 1985
143
and ending up with the psychiatrist. He emphasised that
this enormous demand came from doctors and not from
the patient.
Sir George Godber said that without doubt the level of
funding of health care in the UK was, as a proportion of
resources, much lower than that of any other country.
Leaving out Scotland, which gave over 8 per cent, the
level was under 6 per cent of GNP whereas no other
country in the West was putting in less than 8 per cent
and many put in over 10 per cent. Sir George thought
there was a need for some precise indications of what
should be done and cited the Standing Medical Advisory
Committee's notes on choices of treatment for spina
bifida, which had been accepted and used without prob-
lem. He deplored the way that so-called shroud-waving,
particularly on television, had obscured various issues. It
seemed to him that there must be selection, as not
everything could be done, and that it was necessary to
scrutinise more closely the efficiency (not in terms of cost)
with which things were done. The profession as a whole
had not applied itself enough to forming judgments on the
efficiency of its work, and ways of judgment should be
built into the organisation of all medical work. The
Cogwheel system had been supposed to be about this and
he was sorry that this aspect had not been developed.
There was wastage in the NHS, which should be
eliminated as far as possible. But there was also a great
deal of short-fall in the provision of service. Waiting lists,
which were one way of absorbing some of the problem,
were far too long. He knew that some managed without
waiting lists but in some countries there was no provision
for treatment. He quoted a recent statement of the
American Hospital Association that there were 35 million
Americans without health insurance cover, which meant
that a lot of them went without the health care they
needed. At least this was not the case in Britain but there
were gaps and delays that ought to be eliminated. Much
of the prevention needed was to prevent premature death
from chronic conditions later in life. It would be a long
time before there was financial advantage from this.
Preventive services would not in the short run do some-
thing wonderful in reducing the cost of the health service.
It should not be saving that was looked for, as the longer
old people lived the more care they would need. What
was needed was a change in the pattern of practice as
indicated for general practice by Dr Tudor Hart in his
recent George Swift lecture. Sir George would have liked
to see more of that type of thing coming from the
specialist sections of the profession. Specialist groups
were apt to suggest what should be the minimum service
in a particular field but not to think about the extra
expenditure involved. There was no free lunch; money
put into something had to come out of something else and
there was not enough debate about what should be
surrendered or whether it should be surrendered in order
to do other things.
Sir Douglas Black thought that what Sir George had
said was very important but considered that the waiting
list was not a satisfactory index of need because it was so
readily manipulated.
Dr Crown thought it was vital that clinicians, com-
munity physicians and managers should get together and
see what could be done about the whole area of clinical
efficiency. Savings were clearly required and greater
efficiency was a matter of urgency, otherwise finance-led
decisions would prejudice many vital services.
Mr Nicholls thought that the matter of clinical efficien-
cy should be addressed at the local level, but the strategic
lead should come from the Department. Politicians
should be well advised by central mechanisms so that a
Revenue
allocation
RAWP
target
\
Service
reductions
Service
reductions
Service
reductions
Reduced
cross-boundary
flow
Reduced
teaching capacity
loss of SIFT
Reduced I
cross-boundary
flow
Time
Fig. 1. The teaching district dilemma.
144 Journal of the Royal College of Physicians of London Vol. 19 No. 3 July 1985
framework for making choices was set. Then districts,
management and clinicians could share the business of
making sense out of those choices, but direction would
have to be given by the elected government of the day, as
it provided the majority of the finance.
Sir Raymond Hoffenberg commented on clinical au-
, dit, which had been used in his own unit in Birmingham
for several years. A regular weekly clinical audit meeting
had proved highly successful, with an immediate down-
curve in the number of investigations and prescriptions
ordered and a tremendous improvement in patients'
notes. He was disappointed that clinical audit had not
been taken up by other units in the hospital, and little
audit appeared to be going on in the country as a whole.
It might be argued that audit had saved money and
increased efficiency but had not produced the hoped-for
improvement in outcome. But outcome was difficult to
measure.
Dr R. C. King was glad that the question of evaluation
had been raised but for him the big question was who was
to do the evaluation. It might be that clinical budgeting
would provide the answer and that people on the ground
would be able to take the decisions needed. However, he
thought it would only be done at the central level. Much
money was wasted on needless chemotherapy and on the
GPs' drug bill. There was tremendous room for savings
in these areas but savings would not be made unless
someone in the Department was to say how they could be
achieved. He instanced GI endoscopy as a topic for
evaluation, as the use of the technique had not reduced
the mortality from upper GI haemorrhage, except in a
small group of gastric ulcer patients over 60 years old.
There was a pressing need for intensive clinical evalua-
tion which should be done both locally and centrally with
some guidance from the Department.
DrJ. J. A. Reid appreciated the presentations because
> Sir Douglas Black had given a strategic view, Mr Nicholls
a view of the Region and Dr Crown had spoken about one
particular district which demonstrated that in the end
things had to come down to the local level. But the
particular problems of Bloomsbury were specific to
Bloomsbury and any attempt at a higher level to say how
they could be dealt with was not likely to be successful.
One issue he wished to take up was that of the earmarking
of funds. Clinicians said that they wanted no central
control of direction and wished to be given maximum
freedom. But in relation to their own specialty or super-
specialty they wanted some form of earmarking to take
place. A balance had to be found. Central government
was concerned first with broad guidelines and second with
facilitating local innovation. This could be clinical inno-
vation or in relation to audit. He cited the current
national perinatal mortality study from which no models
were drawn but the results were available for clinicians to
study and decide what sort of deductions should be drawn
in terms of their own practice. Lastly he drew attention to
the 'health for all' targets, an unfortunate journalistic
term invented for the WHO. But there were a series of
specific targets which European countries were pledged to
try and achieve. These got away from the type of
incremental planning that was a thing of the past. These
targets, if better known, should prove useful tools in the
health service.
Dr L. B. J. Stuyt, formerly the Dutch Minister of
Health, said that there was a great difference between the
British and the Dutch health services. The Netherlands
did not have a health service, but there was free health
insurance and everyone could choose his own insurance
company. He was impressed that in Britain the NHS
could realise its assets, something that could not be done
in The Netherlands. The Dutch government would claw
back any money as unused. He also remarked that the
discussions on ethics would have been difficult to hold in
The Netherlands, where the view on medical ethics was
different. The Dutch view was centred on the system
outlined by Canon Dunstan and made a great distinction
between the ethics of government against the insurance
system, the health.system and individual doctor's de-
cisions. What he had missed was any mention of the
natural end of every patient's history, which was death.
To him one of the most important aspects of medical
ethics was the decisions involved in the treatment, or
stopping of treatment, and care of the dying.
Dr Howard Hiatt, formerly Dean of the School of
Public Health at Harvard University, stressed that the
fraction of resources that went into a health system was
not necessarily an index of the return. It was true that the
USA was committed to a per capita expenditure of twice
the fraction of its GNP as was the UK. Despite the
seemingly unlimited resources available for health ser-
vices in the USA there was increasing talk of cost
containment. This was producing a kind of discipline into
the practice of medicine that was not unhealthy. Tech-
nology assessment was being used to see how resources
were used. Disease prevention did not represent an area
in which large savings could be made. In fact, most
preventive programmes cost more than they saved but
there were compelling reasons, other than financial, for
emphasising disease prevention.
There was growing awareness in America that many of
the issues were not solely medical (although medical
considerations were critical) but involved patients and
society as a whole. He considered that the physician was
first and foremost his patient's advocate. But decisions on
resource allocation were not for physicians alone. It was
important that physicians contributed to these decisions
by making the facts known. It was clear that, with
advances in medical technology and an increasingly
elderly population, demands for health services would
increase and become more sophisticated. The kind of
discipline now introduced into the medical area was less
well developed in other areas such as housing, transport
and defence. The total fraction of world resources devoted
to arms had increased about fivefold since the Second
World War. The whole issue of trade-offs should extend
to these areas, and citizens of the world should know how
much more could be done with the world's resources.
In winding up the discussion, Sir Douglas Black
pointed out that the area between different funding
authorities was important because it was the first casualty
when funds became short. He added that high tech-
nology, properly employed, was cost effective. The big
Journal of the Royal College of Physicians of London Vol. 19 No. 3 July 1985 145
waste came from poorly applied routine low technology.
Dr Crown said that evaluation could not be done without
manpower and investment in information, so it was a
resource. The procedure needed clinical involvement and
she thought that the good offices of the Royal Colleges
could be used to approve some of the training posts, for at
least some months of their tenure, as time to be spent on
evaluating a problem within a specialty. Mr Nicholls
referred to the continued debate of centre versus periph-
ery and thought that for evaluation there should be more
central activity. Performance indicators had been called
inadequate but were improving. The review system
which he had mentioned could be used for open debate at
various levels. Finally, he thought that cost containment
was not such a valuable term as cost awareness.
Reference
1. Black, D. A. K. and Pole, J. D. (1975) British Journal of Preventive and
Social Medicine, 29, 222.
|
PMC005xxxxxx/PMC5371152.txt | The Physician Decried: a Random Historical
Survey, 1450-1750
A. L. WYMAN, MD, FRCP
Honorary Consulting Physician, Charing Cross Hospital, London
Many doctors find it hard to understand why in an age
when they can help the sick more than ever before, they
seem to be increasingly disliked. According to Andrew
Malleson, 'Medicine becomes more impersonal, and
because of this the hostility between patients and doctors
increases'fl]. Maybe, but there has never been a shortage
of grumbling patients and grumbling relatives, however
far back we go. It may be some sort of consolation to
unhappy and unappreciated contemporaries to find that
wary, sceptical, and even unpleasant critics of the profes-
sion have been on record for a very long time. The
physician in particular has often been the victim of verbal
assault, judging from a casual reading of old letters and
memoirs. It must be remembered that this view is very
restricted. At one time only the wealthy could afford
physicians, and only the literate could write down what
they thought.
Across the centuries rings Margaret Paston's warning
to her husband in 1464: 'Also for Goddys sake be ware
what medesynys ye take of any fysissyanys of London. I
schal neuer trust to hem be-cause of yowre fadre and myn
onkyl, whos sowlys God assoyle.' Originally she had had
faith in doctors, but she must have been upset by the
treatment of her uncle who had been wounded in an
ambush in 1452. He seemed unlikely to survive '. . . but
if he have redy help; and therefore he shal into Suffolk
this next weke to myn aunt, for there is a good fesician
and he shal loke to hym'[2]. Unfortunately he died after a
long and painful illness in the following year, and we can
imagine the recriminations that must have followed. On
the other hand, Richard Cely, writing from London to his
son George in Bruges in 1479, urges him to 'Be as mery
as ye can and spare for no coste of syche tyngke as may be
good for you in good mete (and) dryke; and youre
fessychons, doe be there consell and plese them at my
coste . . .'[3].
Disputes over fees can be very distressing and a doctor
had to seek protection from an irate husband about the
year 1489, when Master Anthony appealed to Sir Robert
Plumpton: 'And also praying you to be my good master,
(for I understand a man of Spofforth, which I had his
wyfe in cure, will arrest me,) . . . Ye understand that I
have receved xs. and xxd., and of that silver I have spent
xs. of medcins; and also, Sir, as you and this man agres of
this silver, what he shold have againe, he shall content
him'[4]. We hope that a settlement was reached and that
Master Anthony was persecuted no further.
The strong-minded young woman with a will of her
own, quite undisposed to take the doctor's word as law,
and determined to go her own way, is no novelty. Our
predecessors in the seventeenth century faced the same
problem. Elizabeth Walker (nee Sadler), 1623-1690, be-
came when a young girl, so depressed and unwell that her
father was alarmed and called in one of the leading
London physicians, John Bathurst, Fellow and Elect of
the College, and later physician to Cromwell. From her
account we may suspect that Elizabeth suffered from
anorexia nervosa: 'The Physician came to me one morn-
ing before I was out of Bed; he perceived my Distemper to
be most Dejectedness and Melancholly. With other talk,
he discoursed very piously with me. I took the freedom to
tell him, that I thought I did not need a Physician and
with the expression of my respects, desired him to forbear
coming to me; which the good man did not take ill, but
with good counsel left me.' She left home for a year. 'For
half a year I do not know that I slept, if I did it was very
little ... If I descried anything that was gratefull to my
Appetite, when it was brought me I durst not make use of
it, because I thought it to be the satisfaction of a base
Sensual Appetite. I did eat very sparingly, which, with
my much weeping, occasioned me some little inconve-
nience, which became habitual'[5].
Equally determined to put the doctors in their place
was Lady Talmash, afterwards Countess Dysart, and
later still Countess of Lauderdale. She was a gifted,
quick-witted young woman, well educated and good-
looking, but also an intriguer, greedy for wealth and
power. She had a violent temper and was obviously a
difficult person to handle. Dorothy Osborne, in one of her
letters, observed ' . . . and my Lady Talmash, that says
she can do whatsoever she will, cannot believe whatsoever
she pleases. 'Tis not unpleasant, methinks, to hear her
talk, how at such a time she was sick and the physicians
told her she would have the small-pox, and showed her
where they were coming out upon her; but she bethought
herself that it was not at all convenient for her to have
them at that time; some business she had that required
her going abroad; and so she resolved she would not be
sick, nor was not'[6].
The doctor's handwriting is always a subject of ridi-
cule. Even the great William Harvey was not immune.
Aubrey informs us that 'He wrote a very bad hand, which
(with use) I could pretty well read'[7], A Lancashire
landowner, William Blundell of Crosby Hall, felt very
192 Journal of the Royal College of Physicians of London Vol. 19 No. 3 July 1985
J
strongly on this score. Sometime about 1680, he com-
mented, 'A good character adds much to a well-indited
letter, but the faults of an ill-indited letter are much hid
by a character which is not easily read. My physician [Dr
Worthington of Wigan] wrote unto me most material
prescriptions in time of my great danger by sickness. I
showed these unto three most expert readers, and neither
they or I could read it, or understand the main points of
the letter. I told the writer how ill he had done therein.'
Unabashed, the doctor swept the criticism aside. 'He
answered that the letter was so plainly written that there
was never a boy in Wigan school unto whom the same
was not legible'[8]. In 1747, Robert Campbell, no lover
of physicians as we shall see, discussing the requirements
of the apothecary, wrote: 'He must understand the
Physical Cabala the mysterious Character of an unintelli-
gible Doctor's Scrawl'[9], So little change has there been
that in 1984 a medical secretary is moved to complain: 'I
can tell you, with feeling, that there is already an infallible
method of keeping the public (and most of the staff) in
complete ignorance regarding the patient's health and
treatment. It's called doctor's writing'[10].
Some themes continually recur. The failure of the
doctor to attend is a familiar one. In 1711 Nicholas
Blundell sent his servant to Wigan to fetch his regular
physican to look at his wife's leg, 'but the Dr Came not
back with him'fll]. Considering the distance of some 20
miles, the state of the roads, and the scarcity of doctors,
there was probably a good excuse. In 1720, Ralph Palmer
related how he had sat up all night with his wife when she
had been suddenly taken ill. 'I sent for Sir R. B. [Richard
Blackmore] at 12 at night, but he would not come out of
his bed, then I sent for our Apothecary, after that to Dr
Smart of the Hospital, till Dr Chambn. could
come . . .'[12]. Snide remarks and grumbles about doc-
tors' fees continue to be uttered, as presumably they
always will be as long as private practice exists. In 1705
Lord Fermanagh informed his son-in-law that 'Dr Breach
of Oxford hath this week been a Circuit amongst his
Patients and visited at Mr Prices, Mr Hains, Parson
Dancers, Mr Phillips the Atturney, and Mr Pigots, at all
which places I believe he hath well lined his Pock-
etts . . .'[13], Lower in the social scale, the shopkeeper,
Thomas Turner, whose wife was a very sick woman,
bitterly noted in his diary in 1760: 'Dr Poole, coming to
see a child of his, paid my wife a visit, and charged me
10s.6d: really a fine thing it is to be a physician, who can
charge as they please, and not be culpable according to
any human law'[14].
Doubt about the value of the services of doctors is
commonly expressed, even though the scepticism could
V exist side by side with such beliefs as the cure of the
King's Evil by the royal touch. Lord Fermanagh in 1715
'-V. wrote that '. . . Dr Fruen was with Lady F. last Friday
and hath prescribed her a course of Phisick, but I think
she finds no benefitt by it, and therefore I do not consult
the Doctors, tho' I am not at all well, I believe her
ailement is chiefley Colick, which I think no Dr can cure
noe more than the Gout'[15], Robert Molesworth re-
: ( vealed his anxiety about his daughter when he wrote to
his wife in 1713, 'Pray do not let the midwives (when
Cloky cries out) precipitate too much Nature's work. Let
Nature have time to operate: she is a kind mother, and we
often spoil her work by being over hasty. Lord keep us
from physicians and midwives'[16].
Virulent criticism of the profession can be found long
before the era of Ivan Illich. Robert Campbell published
The London Tradesman in 1747, as a guide to suitable
occupations for boys. He deals quite reasonably with the
apothecary and the surgeon, but the physician comes in
for a lashing. Contemporaries must have found his views
objectionable, although we today may find them amusing
and to some extent truthful. 'To acquire this Art of
Physic, requires only being acquainted with a few Books,
to become Master of a few Aporisms and Common-place
Observations, to purchase a Latin Diploma from some
Mercenary College, to step into a neat Chariot and put
on a grave Face, a Sword, and a long Wig; then M.D. is
flourished to the Name, the pert Coxcomb is dubbed a
Doctor, and has a Licence to kill as many as trust him
with their Health.' A disparaging account of the functions
of the Royal College of Physicians concludes: '. . . but
their Dictates, neither hinder their own Members, or
others who have not that Honour, from following their
own Whims; but their Approbation is necessary to an
Increase of Patients, and to establish the young Physi-
cian's Reputation, though of very little Significance
towards the Sanity of the Public, or the Cure of particular
Maladies'[17].
We do not really know what people thought about their
doctors in days gone by, but we can guess that most were
satisfied and some were disgruntled. The views of the
latter usually make the more amusing and interesting
reading and probably distort the general picture. Reflect-
ing on the unkind comments made about his predeces-
sors, the physician of today may justifiably conclude that
there was never a golden age when all patients had
complete trust in their medical advisers, deferred to their
every opinion, and were profusely grateful. John Owen
(1560-1622) put the truth into verse.
God and the Doctor, we alike adore
But only when in danger, not before.
The danger over, both are alike requited.
God is forgotten and the Doctor slighted.
References
1. Malleson, A. (1973)Need Your Doctor be so Useless?, p. 105. London:
Allen & Unwin.
2. Davis, N. (ed) (1971) Paston Letters and Papers of the Fifteenth Century,
Vol. 1, pp. 291, 246. Oxford: Clarendon Press.
3. Hanham, A. (ed) (1975) The Cely Letters, p. 64. London: Oxford
University Press.
4. Stapleton, T. (ed) (1839) Plumpton Correspondence, p. 78. London:
Camden Society.
5. The Holy Life of Mrs Elizabeth Walker (1690) pp. 20-22. London.
6. Parry, E. A. (ed) (1914) Letters of Dorothy Osborne, p. 249. London:
Dent.
7. Dick, O. L. (ed) (1972) Aubrey's Brief Lives, p. 287. Harmonds-
worth: Penguin.
8. Gibson, T. E. (ed) (1880) A Cavalier's Notebook, p. 202. London:
Longmans, Green & Co.
9. Campbell, R. (1747) The London Tradesman, p. 64. London.
Journal of the Royal College of Physicians of London Vol. 19 No. 3 July 1985
193
10. Kitta, E. E. (1984) World Medicine, 19, 9.
11. Bagley, J.J. (ed) (1968) The Great Diurnal of Nicholas Blundell, Vol.
1, p. 293. The Record Society of Lancashire and Cheshire.
12. Verney, M. M. (ed) (1930) Verney Letters of the Eighteenth Century,
Vol. 2, p. 81. London: Benn.
13. Ibid., Vol. 1, p. 223.
14. Turner, T. (1979) The Diary of a Georgian Shopkeeper, p. 47. Oxford:
Oxford University Press.
15. Verney, op. cit., ref 13 above, p. 327.
16. Historical MSS Commission (1913) Report on MSS in Various
Collections, Vol. 8, p. 264. London: HMSO.
17. Campbell, op. cit., ref. 9 above, pp. 41, 46.
|
PMC005xxxxxx/PMC5371153.txt | Book Review
Psychosocial Stress and Cancer,
by C. L. Cooper. John
Wiley & Sons, Chichester, 1984. 265 pages. Price ?17.
The possibility that emotion might affect the onset, or
influence the progress of cancer has intrigued physicians
since the time of Galen. Walshe and Snow, both nine-
teenth century physicians, are quoted in the introductory
chapter as including depression and reversal of fortune
among the events that may lead to cancer. The idea is not
new, but has been largely overshadowed by more modern
attempts to define external agencies. Although this
approach has been partly successful, and environmental
hazards such as smoking tobacco, asbestos and certain
industrial chemicals are now recognised, much remains
unexplained, and review of the evidence for the role of
psychosocial stress in causing malignant disease and
affecting its course is timely.
This book serves this purpose very well. It is a multi-
author work by a number of distinguished contributors
who maintain a properly critical attitude throughout. The
book starts with a history of the subject, and then a
careful examination of the methodology is followed by an
account by Eysenck of the relationship between stress-
prone personalities and lung cancer. The relationships
between life events and cancer are critically reviewed by
Paykel, and possible avenues for further research dis-
cussed. This is followed by a consideration of how the
mind may affect the body's propensity to develop malig-
nancy, and consideration is given to how established
cancer may be affected by management of the psyche.
Finally, there is an excellent summary of the various
approaches that have been used in more than 30 studies
on the subject. There is enough evidence to recommend
that as far as aetiology is concerned, more sophisticated
studies are justifiable to confirm or refute the apparent
relationship between emotional disturbance and cancer
and its progress. There is no doubt that much greater care
will be necessary to define the' types of cancer, construct
proper controls, and classify the types of emotional stress
and, if possible, quantify it. Nobody would, I suspect,
have much difficulty in accepting this suggestion, but I
found the recurring theme throughout the book, which
attempts to explain the mind-body interaction on the
basis of perturbation of the immune system (the friendly
Zeitgeist of the alternative medicine lobby), wholly un-
convincing. A few experiments showing transient sup-
pression of subsets of the lymphocyte population in
patients with emotional stress seem to be a quite in-
adequate basis for advancing such a hypothesis. Immuno-
suppression and 'immunosurveillance' are now seen as
unlikely to be relevant as factors in the cause of common
cancers, and indeed may be wholly irrelevant.
The subject is so complicated that one is easily led into
such remarkable conclusions as that of a very logical
Frenchman, M. Tanchou, who is quoted as saying in
1843 that since cancer was a disease of civilisation, and
since the incidence of cancer in Paris was four times that
of London, ergo the French were four times more
civilised!
This book is concerned with the possibility that people
with certain personalities may be more prone to cancer
than others. While we accept that smoking tobacco and
cancer are related, are we yet prepared to accept that
those patients who show a higher degree of neuroticism
are less likely to develop carcinoma of the bronchus? After
all, it has not been difficult to accept that personality
types are associated with a higher rate of cardiovascular
disease. We come back to something we have known all
along?that the soil is as important as the seed.
I think you would enjoy reading this book.
J. S. Malpas
146 Journal of the Royal College of Physicians of London Vol. 19 No. 3 July 1985
|
PMC005xxxxxx/PMC5371155.txt | J
A Survey of Non-embolic Stroke in Adults
under 50 Years of Age
J. A. LEDERMANN, MB, MRCP(UK)*, Medical Registrar, Whittington Hospital, London
P J. MURPHY MB, MRCP(UK)f, Research Registrar, Chelmsford and Essex Hospital
M. HAMILTON, MD, FRCF| Consultant Physician, Chelmsford Group of Hospitals,
Chelmsford, Essex
B. I. HOFFBRAND, DM, FRCFJ Consultant Physician, Whittington Hospital, London
There have been many studies of non-embolic stroke in
young adults from different parts of the world, including
the USA[l-3], India[4,5], Kenya[6] and Scandinavia[7].
In spite of the widely differing populations studied and
methods used, it is apparent that hypertension and age,
as in older patients, are the most important identifiable
risk factors. In all series a significant number of cases
.have no apparent cause. Surprisingly, at the time our
investigation was begun, there had been no study in the
UK of stroke specifically in young adults.
Methods
In an attempt to determine the causes of stroke in young
adults we conducted a retrospective survey of completed
stroke in patients under 50 years of age admitted to
hospitals in the North East Thames Region between 1st
January and 31st December 1980. The study was com-
missioned by the Research Group of the North East
Thames Physicians Club.
All hospitals within the North East Thames Region,
with one exception, co-operated in the study. Four
hundred and fifty-three sets of case notes obtained
through Hospital Activity Analysis under rubric codes
431-436 and 342 were reviewed and re-classified by us,
excluding cases of subarachnoid haemorrhage, arterio-
venous malformation, tumour and non-cerebrovascular
disease. One hundred and thirty-three cases were ex-
cluded due to mis-coding, in addition to those admitted
with an old stroke (48), transferred from a hospital
outside the region (22), transferred to another hospital
within the region (14) and those whose notes were
unavailable (39). We also excluded 41 cases of transient
ischaemic attacks, in which the neurological signs cleared
within 24 hours, and 22 cases of cerebral emboli. The
notes of 134 patients were available for further study at
least one year after the stroke.
* Present address: Department of Medical Oncology, Charing Cross
Hospital, London W6.
fPresent address: Department of Geriatric Medicine, Addenbrooke's
Hospital, Cambridge.
Patients were classified as hypertensive if this diagnosis
was recorded or the diastolic blood pressure was greater
than 110 mmHg on one reading, or greater than 100
mmHg on two readings. Information on possible risk
factors, namely, smoking habits, high alcohol consump-
tion, impaired glucose tolerance, hyperlipidaemia (fast-
ing cholesterol > 6.7 mmol/litre, fasting triglyceride >
2.3 mmol/litre), high packed cell volume (men >0.5,
women > 0.45) and past history of cardiac and cerebro-
vascular disease were recorded if available.
Strokes were defined as haemorrhagic, thrombotic or of
unknown type, depending on evidence from CAT brain
scans, arteriography and postmortem information. A
patient with a stroke and normal CAT brain scan was
classified as having a thrombotic stroke.
Statistical analysis was by chi-squared tests.
Results
There were 88 males and 46 females who had suffered a
stroke under 50 years of age. The estimated adult popu-
lation served by the North East Thames Region hospitals
(excluding the one not surveyed) is 1,669,300, which
gives an annual incidence of 7.9/100,000 between 15-49
years. The number of cases increased as expected with
each quintile, but the apparently more marked increase
among the males, 45 per cent of whom were aged 45-49
years compared with 28 per cent of the women, was not
significant (x2 = 3.73, /5<0.1) (Fig. 1). Of the total, 56
patients (42 per cent) were hypertensive, 45 being men.
The incidence of hypertension in men (51 per cent) was
significantly greater than in women (24 per cent;
X2 = 9.45, .P<0.01). Hypertension had been previously
diagnosed in 34 cases (61 per cent), 25 of the hypertensive
men (56 per cent) and 9 of the hypertensive women (81
per cent), a difference that did not reach statistical
significance (%2 = 2.55, P< 0.2).
Analysis of 10 putative risk factors for stroke is record-
ed, comparing hypertensive and non-hypertensive groups
(Table 1). The male to female ratio of hypertensive and
non-hypertensive stroke in our study was 4.1:1
Journal of the Royal College of Physicians of London Vol. 19 No. 3 July 1985 163
Table 1. Risk factors
Hypertensive
n = 56
Non-hypertensive
n = 78
Smoking
Diabetes mellitus
High PCV
High cholesterol
High triglyceride
Previous cerebrovascular
disease
Previous cardiovascular
disease
Alcohol*
Age 40-49 years
Male: female
31/45 (69%)
5/51 (10%)
7/48 (15%)
1/16 (6%)
4/16 (25%)
12/53 (23%)
3/54 (7%)
38/64 (59%)
7/75 (9%)
9/67 (13%)
3/19 (16%)
2/19 (11%)
14/73 (19%)
11/73 (15%)
14/56 (25%) 12/78(13%)
(X2= 1.92 NS)
49/56 (88%) 41/78 (53%)
(X2 = 18.05, PC0.001)
45:11 43:35
(X2 = 9.45, PC0.01)
*Alcohol intoxication or known
regular large consumption of alcohol
(P< 0.001) and 1.2:1 (P< 0.1) respectively. Of the hyper-
tensive patients 88 per cent were between 40 and 49
years, significantly more than in the non-hypertensive
group (53 per cent, P< 0.001). Although the data base is
incomplete there was no obvious difference in the preva-
lence of any other single factor between the two groups
and no suggestion that the non-hypertensive patients had
an excess of these factors. Information was not available
on the number and distribution of different racial groups
in the analysis of these risk factors. A diagnosis of
syphilitic arteritis was made in two male patients and
sarcoidosis and an unspecified connective tissue disorder
in two others. In one patient leukaemia resulted in a
cerebral haemorrhage.
A pathological diagnosis was made in 88 cases (66 per
cent) on the basis of CAT brain scans (77 cases), arteri-
ography (34 cases) and postmortem. The diagnosis was
unknown in 46 cases, 55 per cent of the hypertensive and
19 per cent of the non-hypertensive group (x2 = 18.88,
P< 0.001). There were in both groups, where the
diagnosis was known, approximately twice as many
cerebral infarcts as haemorrhage. At the time of study at
least one year after the acute stroke there had been at least ,
28 deaths (21 per cent). There was no significant differ-
ence between the mortality of the hypertensive and non-
hypertensive groups (22.2 per cent and 19 per cent
respectively). However, of those known to have had a
cerebral haemorrhage 10 (34.5 per cent) died compared
with a mortality of 6 (10 per cent) for the cerebral
infarction group (x2 = 5.1, P< 0.05). Twelve (26 per cent) f
of the patients with unknown pathology also died.
Discussion
j
A study based on a retrospective survey of hospital case
notes has obvious limitations, two major sources of error
being death prior to admission and the management of
milder cases at home. Nonetheless, our estimated inci-
dence of stroke in those under 50 years of age of 7.9/
100,000 is similar to that of 10.9/100,000 calculated from
the figures of Brewis et al. [8], also based on case note
review. In a more recent community-based study the
incidence was 17/100,000 but this included patients up to <
54 years of age as well as a small number of cases of
subarachnoid haemorrhage[9], In a recent study of stroke
in people under 55 years of age based on in-patient
records and death certificates, Arbuckle et al. [10] found
annual age-specific hospitalisation rates of people aged
under 35, 35-44 and 45-54 to be 3, 20 and 63 cases/
100,000 respectively.
Hypertension is recognised as the single most import-
ant risk factor for stroke at all ages in both sexes of all
racial groups studied[ll,12]. The risk is graded according
to blood pressure throughout its range. Not surprisingly,
in view of differing populations and diagnostic criteria,
the incidence of hypertension reported in series of stroke
in young adults varies widely, from 19 per cent in
India[5] to 41 per cent and 78 per cent in cerebral '
infarction and haemorrhage respectively in a largely black
population in the USA[13], Of our cases 56 (42 per cent)
were hypertensive by our criteria, 34 of them (25 per cent
of the total series) being previously known to have a
raised blood pressure before the stroke, a figure close to
that of 21 per cent noted by Arbuckle et al. [10], who did
not record newly diagnosed hypertension. In an earlier
prospective study 54 per cent of acute stroke patients in a
hospital in the North East Thames Region were hyper-
tensive and a majority (32 of 35) were previously diag-
nosed and in a large part poorly controlled[14].
Several risk factors (Table 1) apart from hypertension
and age have been implicated in non-embolic stroke and
have been recently reviewed by Kurtzke[15]. There is
considerable controversy about which, if any, are depen-
dent and important factors in stroke production and
Kurtzke dismisses the evidence that body weight, blood
cholesterol, lipids and the contraceptive pill are implicat-
ed. Sex appears to play a small part, the incidence of
stroke, especially in younger age groups, being higher in
50-
40
ta 30
20
10 H
| | Male = 88
? Female = 46
Total=134
15-19 20-24 25-29 30-34 35-39 40-44 45-49
Years
Fig. 1. Distribution by age of patients with stroke.
164 Journal of the Royal College of Physicians of London Vol. 19 No. 3 July 1985
men than women[15]. This is apparent also from the
Framingham data[16], the incidence of stroke in the 45-
54 age group being 1.8:1 male:female. In this study there
were four times as many men as women in the hyperten-
sive group but no sex difference in the non-hypertensive
group. The hypertensive group was also older than the
normotensive group. However, there was no significant
difference between the other putative risk factors compos-
ing the hypertensive and non-hypertensive groups. We
believe that, in the non-hypertensives, the nature of the
vascular disease is unclear and cannot be dismissed as
atherosclerotic. As Warlow[17] states in his review of the
causes of stroke in young people, 'there is a proportion of
stroke patients in whom no cause can be demonstrated
and it is better to be honest and admit this than to talk
vaguely about premature degenerative arterial disease'.
In two studies from the USA[3,18] this proportion
amounted to about 20 per cent of cases of acute brain
infarction when all known hypertensive, cardiac, oestro-
gen-related and systemic diseases had been excluded.
Critchley[19] has recently reviewed the many non-athero-
sclerotic, non-hypertensive causes of stroke, only five of
which were diagnosed in our series.
The contribution of alcohol intake to stroke by a
hypertensive or other mechanism is of current inter-
est[20,21 ]. A history of alcoholism or acute alcohol
intoxication at presentation was noted in one in five of
our cases with a higher, but not significantly so, incidence
in the hypertensive patients. However, the importance of
alcoholism in acute stroke in young (and older) patients
will only be determined in prospective studies.
This study highlights the need for better control as well
as earlier diagnosis of hypertension, especially in
men[22]. It also identifies another large group of patients
who do not have any obvious underlying risk factors. A
clearer knowledge of the underlying pathology obtained
by modern non-invasive techniques and detailed studies
of the contribution of coagulation and haemorrheological
disorders, is needed in this group of patients.
A cknowledgemen ts
We would like to thank the physicians of the North East
Thames Region who allowed us to study their patients.
References
1. Grindal, A. B. Cohen, R. J., Saul, R. F. and Taylor, J. R. (1978)
Stroke, 9, 39.
2. Louis, S. & McDowell, F. (1967) Annals of Internal Medicine, 66, 932.
3. Synder, B. and Ramirez-Lassepas, M. (1978) Stroke, 11, 149.
4. Abraham, J., Shetty, G. and Jose, C.J. (1978) Stroke, 2, 258.
5. Chopra, J. S and Prabhakar, S. (1979) Acta Neurologica Scandinavica,
60, 289.
6. Bahemuka, M. (1979) East African Medical Journal, 56, 661.
7. Hindfelt, B. and Nilsson, D. (1977) Acta Neurologica Scandinavica,
55, 145.
8. Brewis, M., Poskanzer, D., Rolland, C. and Miller, H. (1966) Acta
Neurologica Scandinavica, 41, suppl. 24, 46.
9. Oxford Community Stroke Project (1983) British Medical Journal,
287, 713.
10. Arbuckle, D. D., Harris, R. I. and Goldacre, M.J. (1982) Public
Health, London, 96, 96.
11. Kannel, W. B. (1970) Journal of the A merican Medical Association, 214,
301.
12. Harrison, M. J. G. (1984) British Journal of Hospital Medicine, 31,
215.
13. Haerer, A. F. and Smith, R. R. (1970) Stroke, 1, 466.
14. Kennedy, P. and Hoffbrand, B. I. (1978) British Medical Journal, 2,
1605.
15. Kurtzke, J. F. (1983) Cerebral Vascular Disease, p.17 (ed M. J. G.
Harrison and M. L. Dyken.) London: Butterworth.
16. Kannel, W. B. (1976) Cerebral arterial disease, p.l (ed R. W. Ross
Russell.) London and Edinburgh: Churchill Livingstone.
17. Warlow, J. (1979) British Journal of Hospital Medicine, 22, 252.
18. Levine, J. and Swanson, P. D. (1969) Annals of Internal Medicine, 70,
807.
19. Critchley, E. M. R. (1984) Postgraduate Medical Journal, 60, 386.
20. Hillbom, M. and Kaste, M. (1981) Stroke, 12, 422.
21. Taylor, J. R. (1982) New England Journal of Medicine, 306, 111.
22. Hamilton, M., Thompson, E. N. and Wisniewski, T. K. M.
(1964) Lancet, 1, 235.
|
PMC005xxxxxx/PMC5371156.txt | Book Review
Research. How to plan, speak and write about it,
edited by
Clifford Hawkins and Marco Sorgi, Springer Verlag,
Berlin, Heidelberg, New York, Tokyo, 1985. Price DM
32 (approx. ?8.75).
The tide of this book is incomplete. It does not deal only
with research but how to communicate its results; it is
mainly about writing, speaking and illustrating and will
therefore be helpful to those many doctors who lecture
and write without thinking of themselves as engaged in
Research. It could have a wide appeal.
The eight chapters, each written by one or two of the
eight authors, are: Research, why do it?; Planning and
protocol; Searching the literature; Speaking at meetings;
What the critical reader looks for in an original article;
Illustrating talks and articles; A guide to statistical
methods; Publication; and there are six appendices in-
cluding one on preparing an MD thesis.
The level is simple. Perhaps this is not a criticism, {
indeed it hardly ever is, but one wonders how many
readers need to be shown a picture of a pocket calculator
or a filing cabinet or a box of record cards. However, the
message is clear and if it were always heeded by speakers
and writers the world would be a better place. Perhaps
more detail and specific examples might have provided a
leavening, for example what does a 'natural ability' to
speak well or badly consist of? The English editor, a noted
wit, might have allowed more of it to show through ? it
does, accidentally, in one charming misprint: vis medica-
trix naturae is translated as the 'healing powder of nature'.
Phrases like 'it cannot be denied that', which are rightly
condemned as superfluous in an appendix, appear in the
text. Doubtless they are put there to give a reviewer
innocent pleasure and the chance to carp at what is a /
thoroughly sensible and helpful book. We would all
benefit by reading it; I have.
David Pyke
4
168 Journal of the Royal College of Physicians of London Vol. 19 No. 3 July 1985
|
PMC005xxxxxx/PMC5371157.txt | Tissue Biopsy of the Lung:
Clinical Applications
DONALD J. LANE, dm, frcp
Consultant Physician, Churchill Hospital, Headington, Oxford
Notable advances in our understanding of disease pro-
cesses invariably follow the introduction of reliable tissue
diagnostic techniques. The leap forwards in nephrology
that came from renal biopsy or in hepatology from liver
biopsy is historical fact. Though it is 102 years since
Leyden first experimented with pulmonary needle biopsy
for the diagnosis of pneumoniafl], it is only over the last
two decades that tissue biopsy of the lung has become a
routine procedure for thoracic physicians. There are now
a plethora of observations using a variety of techniques to
get tissue in some form from the lungs. This review at-
tempts to put the current position into a clinical context.
It is not always necessary to have a tissue diagnosis; in
many instances a working diagnosis and plan for manage-
ment can be made without it, so the clinician must satisfy
himself that biopsy is both necessary and justified under
the prevailing clinical circumstances. To make this de-
cision, various questions beg an answer.
1. Which tissues can be tackled?
2. Which techniques are available?
3. What is the diagnostic success rate?
4. What complications arise?
It is now possible to sample any part of the pulmonary
system and allied structures: the pleura and pleural
cavity, the lung parenchyma, the airways and the medias-
tinum. Help in diagnosis can thus be expected for pleural
diseases, diffuse interstitial lung disease, pulmonary and
mediastinal masses and, of course, endobronchial con-
ditions, especially carcinoma. Tissue samples are ob-
tained primarily for histological diagnosis, though some
techniques will only obtain cellular material suitable for
cytological examination. Any sample may be submitted
for microbiological examination if appropriate.
Some typical clinical examples will serve to illustrate
the problems involved. In the first two the issues are
relatively straightforward and in the remaining three
perhaps more difficult.
Pleural Effusion
In the UK, histological samples from the pleura are
obtained with the Abrams punch biopsy[2]. For a densely
thickened and adherent pleura a Trucut or trephine
biopsy may be more useful.
Pleural biopsies are considered routine procedures in
general, as well as chest units, but dissatisfaction is
frequently expressed about their value. Indeed, in only a
little more than half the biopsies will there be a positive
result[3], Tuberculosis yields its secrets to pleural biopsy
better than most pleural conditions and here 65 per cent
or more may be positive[3], In malignant disease, though
one series did claim a 70 per cent diagnosis rate[4], the
rate is much lower, mostly less than 50 per cent. Some
pleural effusions in patients with bronchogenic carcinoma
are the result of lymphatic block or infection, and so will
never give a positive yield in terms of malignancy.
Cytological examination of pleural fluid is much more
helpful in the diagnosis of malignant disease of the pleura
than is pleural biopsy. In a good comparative study, Frist
et al.[5] examined 44 patients with subsequently con-
firmed malignant disease of the pleura; 43 had positive
cytologic findings, whereas pleural biopsies were positive
in only 16. They found it almost impossible to make
diagnostic comments about 122 benign effusions, but four
of their 10 patients with a tuberculous effusion gave
positive pleural biopsies. Three suggestions may help to
improve the diagnostic yield from pleural biopsy.
(a) Attention to technique. Pleural biopsy is not a procedure
which can be left to the inexperienced or unsupervised
beginner. The punch hole should be pointed laterally and
downwards in the line of the ribs: the biopsy should be
taken when there is still plenty of fluid in the pleural
space: pulling hard outwards after feeling the catch of the
pleura is a sure way of just getting skeletal muscle, and,
finally, multiple biopsies undoubtedly improve the diag-
nostic rate.
(b) The handling of the biopsy material. Improved diagnostic
approaches may well increase the yield from pleural
biopsy. Herbert and Gallagher[6] showed retrospectively
that, in the context of suspected mesothelioma, close
attention to morphology could help to pick out malignant
cases, and that the immunoperoxidase technique always
stained reactive mesothelial cells positively for alphai
anti-chymotrypsin, whereas malignant mesothelial cells
were nearly always negative[7]. An exciting future possi-
bility is the detection of carcinoma antigens on the surface
of malignant cells[8],
(c) New techniques. Those who use the Cope needle claim
it is superior to the Abrams punch[9]. Thoracoscopy
biopsies have found'a favour in Europe not granted them
by the conservative EnglishflO]. The technique is not
184 Journal of the Royal College of Physicians of London Vol. 19 No. 3 July 1985
difficult. The positive histology rate is reported at more
than 90 per cent for visible lesionsfll].
The Endobronchial Mass
The biopsy of endobronchial lesions with the fibre-optic
bronchoscope is now an established and rewarding pro-
cedure. Few District General Hospitals are without access
to this facility. Though results depend to some extent on
the skill and experience of the operator and the pathol-
ogist, if a tumour is visible, as is likely in about half the
cases of neoplasm examined, a positive biopsy can be
expected in 60-90 per cent of cases: one series raised this
to 96 per cent by taking four biopsies[12-14]. Most
centres will also take samples for cytological examination
by brush or catheter and with both histological and
cytological examination, few endobronchial masses fail to
yield a diagnosis?not only of malignancy but of cell type
<. and hence prognosis[15]. Endoscopic operability can be
assessed at the same time. Complications are truly mi-
nor?a little haemoptysis is quite common?but overall
the rate is no more than 2 in 1,000. Fatalities for simple
fibre-optic bronchoscopy are 1 in 10,000[ 16].
Biopsy is less reliable when a tumour, though appar-
ently fairly centrally placed radiologically, is not visible
endoscopically, or when the only visible lesion is external
compression. The fibre-optic bronchoscope has certainly
extended the range of visible lesions beyond the range
possible with the rigid 'scope, but when a tumour is not
visible the diagnosis rate falls to around 40 per cent with
unaided fibre-optic bronchoscopy[17]. However, if the
biopsy forceps can be extended beyond the visible range
under fluoroscopic guidance, the diagnosis rate rises to
two-thirds, or even three-quarters if multiple biopsies are
taken. The Japanese, with a new biopsy shaped like a
curette, claim over 90 per cent diagnosis rate for non-
visible masses[18].
Most disappointing is the situation in which external
4 compression is all that can be seen. Prototype needle
aspiration techniques are now being developed, based on
the needle used for injecting oesophageal varices, which
can be pushed through the bronchial wall into potentially
malignant masses[19], Cytological diagnosis of mediasti-
nal glands is clearly possible and Wang et al. [20] have
used the device for staging lung cancers. In 50 per cent of
their cases transbronchial needle aspiration suggested
non-involvement of biopsied glands. This prediction was
confirmed in three-quarters, but unfortunately this meant
that one in four was a false negative. There is no
comparison yet with mediastinoscopy or with computer-
ised axial tomography in predicting hilar involvement,
but clearly this will come. The technique may well
increase the diagnosis rate for endoscopically invisible
tumours in which there is mediastinal lymph node inva-
sion, but it is unlikely to eliminate all thoracotomies that
eventually reveal an inoperable situation.
The Peripheral Mass
This, by definition, is endoscopically invisible and radio-
graphically appears quite separate from the hilum. There
are two diagnostic approaches?the biopsy forceps endos-
copically directed under fluoroscopic control, and the
percutaneous approach, using fine needle aspiration or
possibly needle biopsy, which also requires fluoroscopic
control.
For localised peripheral pulmonary masses, fibre-optic
bronchoscopy has some disadvantages. The correct air-
way must be entered and often the pathology is not in the
airway but in the parenchymal tissues around it. The
biopsy forceps may find their way around the mass,
rather than straight into it. So a direct transcutaneous
approach has much appeal. Under fluoroscopic control it
is possible to enter a mass without great difficulty[21].
Needle aspiration, using a fine-gauge needle, is now
popular and widely practised. Malignant nodules will
almost always be diagnosed, the rate exceeding 90 per
cent in primary growths and 70-80 per cent for metasta-
ses [22,23], False negatives are uncommon.
But the technique has three problems, (a) Samples are
only suitable for cytology. Two variant needles, one with
a small side-slot, can allow truly minute tissue samples to
be withdrawn in perhaps half the cases, but this is far
from reliable[24], (b) While malignant disease is readily
diagnosed, benign diseases are usually only recognisable
as not malignant. A specific diagnosis for benign lesions is
rarely recorded for more than 40 per cent of nodules[25],
(c) Complication rate is much higher than with trans-
bronchial biopsy[26,27]. Pneumothorax can be expected
in one in three or four needle aspirations, with a range of
8-49 per cent compared to 2-5 per cent with transbron-
chial biopsy. One in 10 patients will require tube drain-
age for their pneumothorax. Pneumothorax is closely
related to the depth of the lesion and is also more likely if
there is an increase in total lung capacity, as in obstruc-
tive lung disease[28]. Some haemorrhage, either blood
streaking of the sputum or an enlargement in the size of
the nodule, may be recorded in 10-20 per cent with either
transbronchial biopsy or fine needle aspiration, and with
no great advantage of one technique over the other.
Despite these objections several centres have now
reported large series of needle aspirations under fluoro-
scopic control. In an excellent series from a UK centre,
Flower and Verney[29] in Cambridge confidently diag-
nosed 180 tumours in 300 needle aspirations of peripheral
masses, thus removing uncertainty or the need for diag-
nostic thoracotomy from 60 per cent; 102 cases were
interpreted as non-malignant but as in 23 this interpreta-
tion eventually proved to be incorrect, negative fine
needle aspiration must be followed up by repeat aspira-
tion or by more invasive procedures.
Thus, for the peripheral nodule, fine needle aspiration
is likely to make a positive diagnosis in more than 80 per
cent of malignant lesions but has a high pneumothorax
rate, whereas transbronchial biopsy will give a lower
yield, even with malignant nodules, of 60 per cent or less,
though pneumothorax is uncommon. Neither technique
is good at providing a specific diagnosis for benign
lesions.
An alternative approach to the peripheral mass uses the
cutting needle. The Vim-Silverman needle has a bad
record in relation to lung biopsy and although most
Journal of the Royal College of Physicians of London Vol. 19 No. 3 July 1985
deaths seem to have followed biopsy of diffuse lesions, this
needle has been abandoned for lung biopsy. The use of
the Trucut needle for nodule biopsy has recently been
revived. Earlier series were often retrospective and
fluoroscopic control was generally unavailable before
1970. Two recent series of cases record a similar compli-
cation rate to needle aspiration[30,31]. Nodules less than
2 cm in size are difficult to locate but Trucut needling
seems to offer two advantages. First, tissue is obtained, so
that histological, as well as cytological, assessment is
possible and second, because of this, a specific diagnosis
for benign lesions is more often possible. McEvoy's
series[30] has an especially high rate for final diagnosis,
only two cases remaining undiagnosed from a series of 81,
nine of the 11 benign nodules being diagnosed accurately.
Lobar Consolidation
A diffuse lesion relatively well localised to a segment or
lobe suggests pneumonia and in the majority of instances
antibiotics will be used empirically, or expectorated spu-
tum will give the required guidance. Two more difficult
situations have been the subject of recent investigations?
suspected tuberculosis with sputum direct film negative,
and pneumonic consolidation in the immune compro-
mised host.
Smear Negative Tuberculosis
Conventionally there are two solutions: (a) treat empiri-
cally because clinical suspicion is high; (b) wait for culture
results and take serial radiographs. Can invasive proce-
dures make the situation more satisfactory? In two well-
documented series totalling 111 patients, 64 per cent were
diagnosed from secretions obtained at fibre-optic bron-
choscopy[32,33]. Though histological examination of
transbronchial biopsy samples added a few more cases,
biopsy was not especially satisfactory in this setting,
unlike the experience already outlined for tuberculous
pleural effusions.
Two important technical points must be mentioned.
First, lignocaine used as the local anaesthetic seems to
inhibit the growth of mycobacteria and should be used
sparingly if at all[34], and, second, cross-infection is a
hazard if the 'scope is not carefully sterilised after use[35],
Iodophors are not effective and glutaraldehyde or ethyl-
ene oxide is recommended.
Pneumonic Consolidation in the Immune
Compromised Host
This presents a real diagnostic challenge, the possibilities
embracing extension of the primary disease and toxic
effects of therapy, as well as infection, and within the
infection category a range of organisms so wide and
variable that accurate microbiological diagnosis is essen-
tial. The use of invasive techniques to make a diagnosis is
popular. The reported success rates in different series
vary to such a degree that the skills of operator and
microbiologist must be vital factors in the equation.
Many centres will use the fibre-optic bronchoscope, and,
with aspiration of secretions and transbronchial biopsy,
positive diagnoses are reported in 32-79 per cent[36-38].
The greatest success comes from selected series of patients
in whom Pneumocystis carinii pneumonia is suspected[38].
Localised bronchoalveolar lavage is capable of adding
significantly to the diagnosis rate. Hopkin et al. [39] from
Birmingham correctly diagnosed 15 of 16 infections in
renal transplant recipients, by careful and prompt cytolo-
gical and microbiological examination of bronchial wash-
ings. There seems little to be lost and very much to be
gained by using fibre-optic bronchoscopy with local bron-
chial washing along with transbronchial biopsy if not
contraindicated by a bleeding diathesis, in immune com-
promised patients presenting with a localised diffuse
pulmonary lesion likely to be an infection.
Fine needle aspiration, though having a long tradition
of use in pneumonia, seems to have a lower overall
success rate in this setting than fibre-optic sampling[40].
With either approach false negatives present a real dilem-
ma, whether to use antimicrobials empirically or proceed
to open biopsy. The decision will depend on individual
circumstances. Open lung biopsy carries a higher risk but
rarely fails to give an accurate diagnosis of infection, and
histology will define other diagnoses such as drug reaction
or pulmonary invasion by malignancy[41,42].
Widespread Diffuse Pulmonary Disease
Though the structural details available from histological
samples are likely to be of the greatest importance in
diffuse disease, one cytological technique has featured so
largely in recent literature that it cannot be ignored?
bronchoalveolar lavage through the fibre-optic broncho-
scope[43]. How can this technique contribute to the
diagnosis or management of patients with widespread
diffuse interstitial disease?
There are a few instances when lavage fluid will yield
cellular or other material'that will point decisively to-
wards a certain diagnosis[44], but in many instances a
pattern of cell differential counts will be found that
indicates a type of inflammatory response seen in several
disorders[45]. Much has been made, for example, of the
excess of lavage lymphocytes seen in sarcoidosis[46] but
such an excess can be found in other disorders and is not
always found in sarcoid, especially in its later stages[47],
A polymorph excess, though certainly characteristic of
fibrosing alveolitis, will of course also occur in infection
and be enhanced by cigarette smoking[45]. Thus, as a
diagnostic tool, bronchoalveolar lavage is insensitive. In
its use as a means of predicting prognosis or response to
treatment, there is still much to explore. Statistical rela-
tionships have emerged between certain cell patterns and
a particular clinical course, but ability to predict for
individuals is not yet possible[48].
The issue about true tissue biopsy techniques for
widespread diffuse lung diseases centres on the relative
merits of transbronchial and open lung biopsies. Trans-
bronchial biopsy appears to be an ideal technique for
diffuse lesions both because accurate localisation of the
forceps site is not required, so obviating the need for
fluoroscopy, and because the technique is safe. Open
186 Journal of the Royal College of Physicians of London Vol. 19 No. 3 July 1985
biopsy, on the other hand, necessitates thoracotomy with
its attendant complications, but it will produce a substan-
tial portion of tissue from which a histological diagnosis
can be made in almost every case.
How reliable then is transbronchial biopsy? Overall,
diagnoses can be made in about 60 per cent of cases[49].
Within mixed series individual subgroups such as sarcoid
and malignancy are more readily diagnosable. Poor
results are obtained with transbronchial biopsy in diffuse
fibrotic diseases and in the vasculitides[50], Quite often
the histologist is able to give no more than a non-specific
result. Though this reduces the likelihood of a granulo-
matous diagnosis, it does virtually nothing to further
diagnosis in disease categories such as suspected fibrosing
alveolitis[51].
Because of its relative safety, transbronchial biopsy
should certainly be the first step in obtaining a histologic
diagnosis in multilobular diffuse pulmonary disease, but
?>. if it yields normal or non-specific histology this cannot be
regarded as reassuring or helpful. The decision whether
to proceed to open lung biopsy will then depend on the
individual circumstances of the patient and the hospital.
This is certainly the point at which to ask searching
questions about the next stage of the diagnostic cam-
paign. Are there really no other clues to diagnosis, no
other sources of material for a histologic specimen? Does
the clinical course suggest a disease process that might be
amenable to treatment? Can a therapeutic trial be justi-
fied? It may be possible to proceed with a sensible course
of management without the back-up of an accurate
histological diagnosis.
If, on the other hand, an open biopsy is deemed
necessary, it can be expected to yield a diagnosis in over
90 per cent of patients[52]. In a particularly useful
comparison, Gaensler's group produced a specific diag-
nosis in 92 per cent of 33 patients in whom transbronchial
biopsy had given negative or non-specific findings[53].
But with open biopsy there will be complications and pre-
existing lung and general disease may dictate that the
potential risks of open biopsy are not acceptable. Whether
or not the surgeon puts in a drain for the inevitable
pneumothorax depends on his technique, but a persistent
air leak seems to occur in about 6 per cent of cases;
infection of either pleural cavity or wound is recorded in
5-8 per cent. Depending on what size of fluid collection is
recorded, up to 20 per cent will have an effusion. Deaths
are recorded in as many as one in 22, but often this is
because of serious underlying disease[54]. In the best
hands mortality is down to just under 2 per cent[52] but a
rather salutary comment appeared in one series of over
400 open lung biopsies; this noted that, among 19 deaths,
in only four did the result produce 'a major change in
therapeutic management'[54]. The number of patients
with a negative transbronchial biopsy who will be submit-
ted to thoracotomy will depend very much on individual
circumstances, and the gains to be achieved by knowing
the exact histology will have to be balanced carefully
against an overall complication rate of up to 20 per cent,
some complications being serious.
Finally, in all these deliberations, account must be
taken of local conditions. Best results often follow the use
of a technique with which the hospital and its physicians
and surgeons are most familiar. Fluoroscopic control or
easy access to a good cytologist may not be available. On
the other hand, a highly skilled thoracic surgeon and a
dedicated histologist may have been working together for
years. These factors will certainly, and rightly, influence
current practice.
This article is based on a paper read at the College Regional
Conference in Oxford in September 1984.
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A Medical Man with a Flying Machine
To give a Croonian Lecture while still a medical student,
becoming FRCP thirteen years later, and to write on
flying machines for the 1879 edition of Encyclopaedia
Britannica all suggest an unusual medical career. These
events happened in the life of James Bell Pettigrew. The
Bell was on his mother's side, Henry Bell the designer
and builder of the original steamship Comet. James
Pettigrew was born in Lanarkshire and seems to have
spent his boyhood making models, from windmills to
engines. He took a leisurely five years to gain an arts
degree at Glasgow University and then proceeded to
Edinburgh University to read medicine for another five
years. He is said to have worked steadily but not exces-
sively. What suddenly inspired him was the subject set for
the Senior Anatomy Gold Medal, 'The arrangement of
the muscular fibres in the ventricles of the vertebrate
heart'. One evening he rolled his newspaper into a cone
and was surprised to find that the lines of print formed
spirals, the outer spiral being in the opposite direction to
the inner one. Maybe he 'did cry Eureka but he saw
immediately that his dissections of heart muscle would
make anatomical sense if the fibres were considered to
form a spiral figure-of-eight. He went on to demonstrate
this arrangement and gained the Gold Medal. He pre-
sented the work in 1860 when delivering the Croonian
Lecture to the Royal Society. Dr Croone's beneficence
did not, of course, stop at the Royal College of Physi-
cians; he also endowed a lecture at the Royal Society.
Graduating MD in 1861 Pettigrew became house
surgeon to the great Syme at Edinburgh Royal Infirmary
and it was Syme who obtained for Pettigrew the post of
assistant curator to the Hunterian Museum at the Royal
College of Surgeons in London. There he made many
dissections for demonstration and continued his anatomi-
cal research.
Figures-of-eight were always in his mind and he ap-
plied them to the movement of the wings of birds and
bats, gradually elaborating his theory of flight with wing
movements forming a figure-of-eight wave pattern. His
full theory was announced in 1867 and created a great stir
in the Victorian world of science.
All this work temporarily broke his health and he
retired to the south of Ireland where he rode, fished and
made model flying machines. However, he found that
Irish workmen could not construct his models with the
precision he required so he returned to Glasgow where
some successful models were made. He continued with
his models long after he returned to academic work. His
last machine, built in 1887, stood ten feet high, weighed
252 lb and had a thirty foot wing span. It was powered by
a high pressure steam engine. It did manage to leave the
ground, just.
Regaining his health by the autumn of 1869 Pettigrew
was appointed curator to the Museum of the Royal
College of Surgeons of Edinburgh and pathologist to the
Royal Infirmary and became a Fellow of the Royal
Society. Considering his work for the surgeons it is a little
surprising to find him elected FRCP by the Edinburgh
College of Physicians in 1873. That prefaced his appoint-
ment in 1875 to the Chair of Medicine and Anatomy in
the University of St Andrew's. From there he exerted a
benign influence on university education, working for a
broader curriculum in the sciences and modern lan-
guages. In 1877 the universities of Glasgow and St
Andrew's elected him their representative on the General
Medical Council. Some career for an inventive Scot.
188 Journal of the Royal College of Physicians of London Vol. 19 No. 3 July 1985
|
PMC005xxxxxx/PMC5371158.txt | Book Review
Oxford Textbook of Clinical Pharmacology and Drug Therapy
by D. G. Grahame-Smith and J. K. Aronson. Oxford
University Press, 1984. 843 pages. Price ?25 (cloth),
?12.50 (paperback).
This is an excellent attempt to provide a systematic
account of clinical pharmacology for clinical medical
students, for those in pre-registration years, and a refer-
ence work for practitioners. It is excellent because it
seems to be based on four prime objectives: to distil from
the mass of material available those principles which are
essential to the subject, to describe these in the most direct
and unambiguous ways, to confine material to what is
relevant in clinical medicine, and to reduce explanations
to the minimum that logic can allow.
Interestingly enough, these enacted aims show the
difficulties of the subject quite starkly. First, there is the
fact that clinical pharmacology embraces knowledge in
two realms, that of linear and branching logical argu-
ment, and that of the fact store. The authors have grasped
this nettle firmly by providing a text with two chief parts,
a textbook and a formulary, so avoiding the confusing
aspect so often seen where these are mixed. But this
benefit has inevitable disadvantages. Testing the text with
common clinical problems showed that the tiresome
problem of adding a non-steroidal anti-inflammatory
drug to therapy with warfarin turns up very well in the
pharmacopoeia but not in the text; someone who looked
only at the text would emerge uninformed.
The second dilemma is that many terms used in clinical
pharmacology have a very precise mathematical meaning
in the scientific context, but a blurred and confusing
meaning in common clinical usage. One example is the
difference between efficacy and potency, which these
authors avoid by omitting them both, while giving a fine
and clear account of dose-response curves. This is one
way round the problem, but the terms are used, and are
confused dangerously at times.
Perhaps the central problem of the subject is the fact
that its scientific base, though fast encroaching on the
field of clinical practice, has not yet met it in some parts.
Cardiac arrhythmias provide examples where practice at
the bedside in emergencies often has little to do with what
is known of the many drugs given to the patient, and
where some of the drugs given most often do not even
appear in the classification of drug actions used most
often in teaching. The authors admit this unambiguously,
and step back wisely from any attempt to force the
situation into apparent logic. They discuss it from the
standpoint of what matters in real clinical decisions. But
they relegate much of the theory to the pharmacopoeia
under 'lignocaine', which has a confusing effect despite
adequate cross-references.
The sections on basic theory vary in their level of
presentation. The one on clinical trials is weak in its
discussion of the central topic, bias (e.g. 'the purpose of
randomisation is to eliminate bias', and 'placebos are
used in order to achieve blindness') but strong in its
presentation of the Type II error in relation to numbers in
a study.
It is good to see a very readable and practical section on
prescribing, sources of drug information, and pharma-
ceutical knowledge.
The book is elegantly set out, strongly bound, and is a
well presented, readable text which avoids the detractions
of 'short notes' despite its concentration on essentials.
Where basic knowledge does not yet match what is known
from clinical experience, it is refreshingly honest. House-
men will find it a fund of practical wisdom; for example,
when discussing prescribing in secretory organ failure,
the text avoids the Scylla of needlessly elaborate nomo-
grams and the Charybdis of failing to say where these
break down in practice. This is a thoroughly commend-
able work in the best 'Oxford Medical' tradition.
D. W. Vere
Journal of the Royal College of Physicians of London Vol. 19 No. 3 July 1985 183
|
PMC005xxxxxx/PMC5371159.txt | Editorial
'Go and see what little Tommy is doing and stop him' used to be a
well worn family maxim. Its results were not particularly encourag-
ing. Little Tommy felt paranoid in the face of authority and
considered his worst action was justified because it was banned. Just a
whiff of this is detectable in attitudes to the organisation of medical
practice. Dr Tommy feels that he can scarcely write the word
prescription without being engulfed in wordy dispute. Once a
prescription was praised for its elegance and now should be com-
mended for its scientific specificity. These terms are certainly not
applicable to the recent debate on prescribing, or rather what drugs
should not be paid for, within the NHS. A clumsy intervention from
on high led to an almost Pavlovian response from interested parties.
Their scripts, not their prescriptions, could have been written in
advance by a disinterested observer. Valid statements by those who
made, prescribed and used drugs were obscured by highly flavoured
decorations.
In nice clear instances the choice of a prescription is easy.
Thyroxine for the treatment of myxoedema is a good example; regrets
for the passing of thyroid extract B.P. are no longer heard. It is the
multiplicity of alternatives that brings emotion into choice of drug.
One doctor in his professional life-time will use only a fraction of all
the available drugs. True, there is a plethora of literature to tell him of
the rest but the written word has not always been valid or informative.
It is very easy to look for guidance and find persuasion instead. As so
many 'me-too' preparations have only marginal differences, picking
with a pin is as good as thought when the choice is made. There are
too many drugs all chasing the same symptom.
Generic prescribing has been taught and commonly practised in
hospitals which often maintain a restricted pharmacopoeia. The fact
that authority outside the profession made a statement seems to have
brought out the doctors' latent paranoia. Of course there were
excellent and true arguments used to influence authority but it is a
pity when the inevitability of making choices in medicine is made
more of a problem by confusing issues, and when central authority
omits consultation with concerned parties. Here are the ethics of
tension, inherent in the matter of choice, as Canon Dunstan pointed
out in the College Conference on Priorities in Medicine. It is the calm
thoughtful response to the tensions that matters.
By the very nature of his work the doctor is never a disinterested
observer but always the passionate advocate of his patient's interest.
As an advocate he may fail to acknowledge that satisfaction of his
demands may deprive another's patients of their satisfaction. That
the doctor always knows the best interests of his patients is too easily
accepted. My choice of drug or my department and nowhere else can
slip into my ego trip. But it is also dangerously easy to moralise about
those who must choose when not involved in the choice.
Journal of the Royal College of Physicians of London Vol. 19 No. 3 July 1985
125
|
PMC005xxxxxx/PMC5371160.txt | Book Review
The Health of the Civil Service.
HM Stationery Office,
London, 1985. 81 + vi pages. Price ?4.50.
The Civil Service today consists of half a million non-
industrial civil servants employed at home and overseas,
30,000 industrial civil servants and 83,000 employees of
non-exchequer bodies such as the Forestry Commission
and HM Stationery Office. The MOD (Procurement
Executive) and the MOD (Navy) have separate occupa-
tional health programmes for over 100,000 of their staff in
research establishments, weaponry ranges, ordnance fac-
tories and dockyards.
Medically, they have been looked after by a Medical
Advisory Service (MAS) since 1948, with the old estab-
lished Post Office Medical Service joined to it until 1969.
The MAS was originally located in the Treasury, later in
the Civil Service Department and is now in the Manage-
ment and Personnel Office of the Cabinet Office.
Such a captive population between the ages of 16 and
65 is ideal for studies into the causes of ill-health among
civil servants and on issues, such as smoking, alcohol
abuse, visual display units, environmental asbestos levels
and the health standards of special groups such as firemen
and coastguards. Accordingly, the MAS provides advice
to departments on the medical aspects of recruitment,
sickness absence and retirement, on environmental health
problems and on problems associated with service over-
seas. Its research commitments have been considerable in
the last 50 years, but have been enlarged and refined in
the last 30 years, especially by establishing close co-
operation with research groups such as the London
School of Hygiene and Tropical Medicine and others.
Reports on the health of the Civil Service were published
on several occasions, the last in 1978.
The present elegant study by the Civil Service Medical
Adviser, Dr Adrian Semmence, reports not only on the
changes that have occurred in the work of the MAS, to
which now an Occupational Health Nursing Service is
attached, but also offers some important new lessons.
It shows that white collar civil servants have an average
annual sickness absence of 10.3 days. This corresponds to
4.6 working days lost from a total of 225.5 working days
in 1983. In comparison with the Post Office, Civil Service
figures are lower, because of the higher proportion of
industrial grades in the Post Office. Sickness absence in
the Civil Service is about half the national rate and is
going down. Most serving civil servants can anticipate
drawing their pensions for at least 13 years after retire-
ment. The premature mortality rate in home Civil Ser-
vice (men and women) is about half that of comparable
groups in the country at large. Thus the Civil Service
seems a healthy organisation.
One of the most interesting and important findings
resulted from the Whitehall Study in 1968, which set out
to ascertain factors that predict cardiorespiratory disease
in male civil servants. In 18,403 men, aged 40-64,
working in Whitehall departments, the association of
cigarette smoking, raised blood pressure and blood glu-
cose with an increased risk of premature death from
coronary heart disease was demonstrated. 'Analysis of the
mortality revealed that subjects in the lowest employment
grade (predominantly messengers) had a coronary heart
disease rate 3.6 times that of subjects in the highest grade
(the administrators). Intermediate employment grades
had intermediate risks of death from coronary heart
disease.' This is exactly the reverse of what would be
expected if it were true that stress was a major factor in
heart disease. Moreover, a further study of leisure ac-
tivity in the Civil Service, undertaken by Professor J. N.
Morris (London School of Hygiene), showed that average
levels of physical activity have little, if any, protective
effect against heart disease.
These findings alone secure this report a place as an
important guide for future research.
V. C. Medvei
V
194 Journal of the Royal College of Physicians of London Vol. 19 No. 3 July 1985
|
PMC005xxxxxx/PMC5371161.txt | Sarcoidosis in a Racially Mixed Community
M. W. McNICOL, MB, FRCR Consultant Physician
P J. LUCE, MB, MRCP(UK), Medical Registrar
Department of Thoracic Medicine, Central Middlesex Hospital and Willesden Chest Clinic,
London
The incidence and course of sarcoidosis in different racial
groups varies gready[l-3]. In the last 23 years 497 cases
of sarcoidosis have been seen in the racially mixed
community served by the Willesden Chest Clinic.
The community comprises approximately 90 per cent
of the population of what is now the London Borough of
Brent. In addition to the indigenous population three
large groups can be identified?the Irish, the West
Indian, and an Asian group of Gujerati descent born
either in India or East Africa. Information on the total
population of Brent was provided by the Division of
Planning of this London Borough (Table 1). Details of the
age and sex structure of these populations is not available;
Table 1. Population estimates for Borough of Brent.
1981
1971 No. F/M ratio
British 194,465 157,684 1.06
Irish 21,761 17,878 1.09
West Indian 18,040 16,690 1.11
Asian 7,290 16,679 0.95
both are likely to have shown considerable change in
addition to the change in number. The overall F/M ratios
in 1981 show a male preponderance in the Asian "popu-
lation typical of a new immigrant group. The reasons for
the female preponderance in the Irish and West Indian
populations are not known, but these differences empha-
sise the probability that the immigrant populations have
an unusual structure.
The Patients
Between 1960 and 1983 a total of 497 patients with
sarcoidosis was treated by three physicians?J. R. Mik-
hail, M. W. McNicol and J. F. Riordan. Their investi-
gations and management were generally comparable. We
have reviewed the clinical notes and chest radiographs,
and compared in the four large racial groups the inci-
dence of the disease, the extent of organ involvement, the
outcome and the use of steroids.
The results are presented for 456 patients from the four
main racial groups only: the British, the Irish, the West
Indian and the Asian.
Diagnosis and Assessment
The diagnosis was based on clinical and radiographic
grounds, but confirmation was always sought histologi-
cally, either by biopsy of an involved tissue or by Kveim
test (Table 2). If histological proof of diagnosis was
Table 2. Diagnostic methods.
No.
Positive histology 288
(mediastinal nodes 94% positive)
Positive Kveim 268
(proportion positive 86%)
Clinical criteria 72 (16%)
urgently required and there was no other obvious tissue
involvement, mediastinoscopy and biopsy were undertak-
en. Dating of disease onset is rarely possible, so the initial
information was based on the findings at the time of
diagnosis.
A whole range of investigations was used when appro-
priate.
The evolution of the disease was considered in two
ways. An assessment of activity five years after diagnosis
was made by review of all available data. The classifica-
tion used is shown in Table 3. The final outcome was
Table 3. Classification of results.
0 Recovered; no clinical, radiological or other evidence
of disease
1 Asymptomatic but with objective evidence of persist-
ing active disease
2 Minor symptoms with persisting abnormality or
asymptomatic but on steroids
3 Significant disability
D Death probably related to sarcoidosis
similarly assessed at the time of discharge of the patient
from the clinic, or at the last attendance. A very complete
follow-up (88 per cent) was obtained, with little difference
between the groups (Table 4).
Journal of the Royal College of Physicians of London Vol. 19 No. 3 July 1985
179
Table 4. Incidence and case follow-up.
Calculated Case follow-up
No. of incidence Known Lost
cases per 100,000/yr No. No. %
British
Irish
West Indian
Asian
151
105
165
35
4
21
58
14
133 18 12
86 19 18
151 14 8
31 4 11
Results
Our patients were drawn from populations showing a
significant change in number and almost certainly in
structure during the period of observation. We consider
that the effect of these changes is likely to be so great that
statistical analysis of the data is not justified.
Incidence
The number of patients and the estimated incidence of
the disease by race are shown in Table 4.
Sex and Age
There was a preponderance of females (1.25:1). The age
range was similar for both sexes (14 to 73 years and 14 to
70 years for females and males respectively), but the
mean age in women was higher (35 as opposed to 32
years). In the Irish and West Indian populations the
female preponderance was more marked (1.84:1 and
1.32:1). The mean age in the Irish patients was lower (30
yr female, 28 yr male) and higher in the West Indians (39
yr female, 36 yr male).
Disease Sites (Table 5)
Disease was identified in a total of 1,002 sites, an average
of 2.02 per case. West Indian and Asian patients had
involvement of a greater number of sites. The sites
involved were also classified by frequency of involvement.
Common sites (involved in > 10 per cent of the popu-
lation) were equally involved in the four racial groups,
but infrequently involved sites (involved in 1-10 per cent
of the patients) and rare sites (involved in less than 1 per
cent of the patients) were much more often involved in
West Indian and Asian patients.
Involvement restricted to intrathoracic sites was more
common in the Irish than in the other ethnic groups.
Erythema nodosum was common in the British but rare
in the West Indian; in the Irish and West Indian it was
almost exclusively a disease of women (F:M ratio 10.5:1
and 10.0:1). Involvement of extra-pulmonary sites was
much more common in the West Indian (ENT, heart,
pleura, skin and a wide variety of other sites). The Irish
rarely had skin or eye involvement.
Outcome (Table 6)
In 402 patients the outcome was known. Fifteen years
after diagnosis 54 patients were still considered to have
active disease, the longest duration being 28 years. On
average 64 per cent of the patients recovered within five
years. Fewer West Indians and Asians recovered but in
those who did there was no difference in disease duration
in the different races. Uncertainty about the population
base makes it difficult to draw any conclusion about the
duration of disease in those not recovered at five years.
Table 6. Outcome in 402 patients.
Recovered Not recovered
Average Average
duration duration
No. % yr No. % yr
British 96 72 2 37 28 18
Irish 61 70 3 26 30 20
West Indian 84 55 3 67 45 11
Asian 15 48 2 16 52 8
Total 256 64 146 36
Table 5. Site involvement by race.
Site
British
No. %
Irish
No.
%
West Indian
No. %
Asian
No.
Lung
Mediastinal nodes
Erythema nodosum
Eye
Lymph nodes
Liver
Pleura
ENT
Calcium
Heart
CNS
Total
Average no. of sites per case
61
115
47
14
7
3
3
2
6
1
0
151
40
76
31
9
5
2
2
1
4
50
87
23
3
5
3
0
0
. 5
2
0
105
48
83
22
3
5
3
94
141
11
30
21
18
16
18
4
7
10
165
57
85
7
18
13
11
10
11
2
4
6
16
33
3
1
2
3
0
1
1
0
0
35
46
94
9
3
6
9
3
3
2.6
2.2
180 Journal of the Royal College of Physicians of London Vol. 19 No. 3 July 1985
Table 7. Results by race, assessed 5 years after diagnosis.
% in grade
No. 0 1 2 3 D
British 133 64 22 12 1 2
Irish 86 65 22 12 0 1
West Indian 151 49 23 26 2 0
Asian 31 45 35 20 0 0
Result Five Years after Diagnosis (Table 7)
The West Indians and Asians had a poor result (grade 2
or worse) at five years compared with the British and
Irish. Assessment of results in relation to sites affected
shows much poorer results for extrathoracic disease
(Table 8). The poorer results in the West Indians and
Asians are largely due to this effect of site involvement.
Table 9 shows the proportion of patients who have
recovered with disease in a given site; comparison of
outcome in different racial groups by site is difficult due
to the small numbers of whites affected. West Indian and
Asian patients with purely intrathoracic disease had
disease duration and outcome similar to those of the
British and Irish.
Deaths
There were seven deaths; three British patients with
progressive pulmonary fibrosis, two Irish siblings with
cardiac sarcoid and two West Indians, one with CNS
sarcoid and the other with multiple extrapulmonary
involvement and a cardiomyopathy.
Steroids (Table 10)
Steroids were prescribed on clinical indication and were
given to 209 patients. The proportion of West Indian and
Asian patients given steroids was higher. In the British
and the Irish the commonest indication was lung disease,
but in the West Indian and Asian extrapulmonary disease
was a more frequent indication. West Indian patients
more often required more than one course.
Comparison of patients with parenchymal lung disease
who were given steroids with those to whom no steroids
were given (Table 11) shows that the British patients
treated with steroids have poor results, but that the result
in the Irish, West Indian and Asian differs little from that
of the patients to whom steroids were not given.
Discussion
Our study highlights variations in the course and morbid-
ity of sarcoidosis in different racial groups. The lack of
knowledge of the structure of the population we studied
prevents detailed comparison with previous reports on
prevalence or incidence of the disease[l-4].
The incidence in our British population seems similar
to that previously reported[5]. We found, as has been
previously reported[5,6], a considerably higher incidence
in the Irish living in London. This is apparently more
Table 8. Sites associated with a poor result at 5 years.
Lungs Mednodes Eyes ENT Liver Ca. Heart CNS
British 15 12 2 0 3 3 0 0
Irish 9 9 0 0 1 1 2 0
West Indian 29 33 14 15 11 2 2 0
Asian 6600000 0
Table 9. Proportion recovered at 5 years by site as percentage.
Lungs and
Total Mednodes Eye ENT Liver Ca. Heart CNS
British 76 57 66 100 0 17 0 0
Irish 56 62 66 0 0 50 0 0
West Indian 140 70 28 11 23 25 43 30
Asian 18 42 0 100 0 100 0 0
Table 10. Steroid therapy.
Total Treated Courses
cases No. % 1
British
Irish
West Indian
Asian
151
105
165
35
57
42
94
16
38
40
57
48
39
28
57
11
19
14
37
5
Sites of disease
Lungs EN CNS Liver Other
37 10 0
30 6 1
52 0 10
9 0 0
2 8
0 5
5 27
1 7
Journal of the Royal College of Physicians of London Vol. 19 No. 3 July 1985 181
Table 11. Parenchymal lung involvement
Results by % in grade
No. 0 1 2 3 D
No steroids given
British
Irish
West- Indian
Asian
Steroid treated
British
Irish
West Indian
Asian
11 72 28
12 50 25
14 44 22
6 17 66
44 25 35
33 57 21
72 48 19
10 10 30
0 0 0
17 0 8
34 0 0
17 0 0
30 0 10
18 0 4
32 0 3
60 0 0
than twice the undoubtedly high incidence of sarcoidosis
in the Irish living in Ireland[4], The very high incidence
in our West Indian patients was similar to that reported
in other negro populations[l-3], Our Asian patients
appear to be showing a trend to a similarly high inci-
dence.
Reports on the sex ratio of the patients and the age at
presentation vary considerably. Honeybourne[8] in
South London found a slight female preponderance in
Caucasians and an equal sex incidence in West Indians.
We found a definite female preponderance in Irish
patients, whereas Cummiskey[4] noted a male predomi-
nance (11:9); it would be difficult to account for this
difference on the basis of the known information about
our population structure, which shows an unusually great
male preponderance. The age of our Irish patients was
similar to that reported by Cummiskey and younger than
that of the other groups. Our West Indian patients
showed a very definite female preponderance and the
West Indian and Asian patients were older. A similar
trend in age in West Indians was noted by Honey-
bourne^]. Israel[9] found a younger average age at
presentation in his negro patients; all of Benator's
patients were older?45 years in white South Africans, 35
years in 'coloureds' and 40 years in negroes[2]. It is
possible that these differences have little significance; they
could readily be explained by variation in population
structure and uptake of medical services.
The disease pattern in our Irish patients seems to be
similar to that described by Cummiskey and KeelanflO]
who found extrathoracic involvement to be uncommon,
and also commented on the relative rarity of skin involve-
ment. The pattern of disease is markedly different in
West Indians and probably in the Asians. Disease was
identified in a greater number of sites with a higher
frequency of extrapulmonary site involvement. A similar
pattern has been noted by others[3,9,l 1], The disease
pattern in our West Indian patients appears to be similar
to that of negro populations in North America and South
Africa.
It is difficult to draw firm conclusions about our Asian
patients. The group is relatively small and drawn from a
new and expanding population whose age and sex struc-
ture is almost certainly changing. We also see some
indication of a higher incidence of the disease with more
frequent extrapulmonary site involvement and an in-
creased morbidity. Edmondstone's data[12] suggest simi-
lar findings in South London. There is no good
information on the incidence or natural history of sarcoid-
osis in Asia, and our experience of the disease in Asian
immigrants does not yet permit us to draw any firm
conclusions.
Conclusions about outcome must be guarded. Fewer of
our West Indian patients recovered, and results in them
were poorer. These differences appear to relate to site of
disease and, in particular, evidence of extrathoracic
involvement. In West Indian patients with pure intra-
thoracic disease the proportion who recovered was similar
to that of those of other races, and in patients who
recovered there appeared to be little difference between
the racial groups in disease pattern or duration. The West
Indian patients had more frequent involvement of ex-
trathoracic sites, a pattern itself associated with a poorer
prognosis; there is a suggestion that extrathoracic site
involvement in our West Indians has an even poorer
prognosis. There was a particularly poor outcome in
patients with cardiac or ENT involvement.
Steroids were given on empirical clinical grounds, as
has been the case in most other reported series[9,11,13].
It is not possible to reach any firm conclusions about their
efficacy. In the one single large group of our patients in
which comparison can be attempted?parenchymal lung
disease?they appear to have little effect on the duration
of disease. However, it is clear that the differences in
frequency with which they were prescribed must reflect
commonly held if unsubstantiated views on the indica-
tions for their use.
Summary
Over a 23-year period 497 patients with sarcoidosis were
seen at Willesden Chest Clinic, of whom 151 were
British, 105 Irish, 165 West Indian, and 35 Asian. The
estimated annual incidence was: British 4/100,000, Irish
21/100,000, West Indian 58/100,000 and Asian 14/
100,000.
There was a marked female preponderance in the Irish
(65 per cent) and West Indians (57 per cent). The female
mean age was 35 years, the male mean age 32 years.
Asian and West Indian patients were older (mean 37 and
38 years) and Irish patients younger (mean 29 years).
West Indian patients more frequently had involvement
of the less common extrathoracic sites.
In 402 patients the outcome was known: 64 per cent of
patients recovered within five years but proportionally
fewer West Indians (55 per cent) and Asians (48 per cent)
recovered. The greater morbidity in the West Indian and
Asian patients was particularly associated with extrathor- ^
acic disease in which the results were poor.
Acknowledgements
We are particularly indebted to J. R. Mikhail who
initially stimulated interest in these patients, to J. F.
Riordan for permitting us to study his cases, and to D. L.
182
Journal of the Royal College of Physicians of London Vol. 19 No. 3 July 1985
Mitchell who performed the Kveim tests on our patients,
and who was a constant source of advice and help.
References
1. Maycock, R. L., Bertrand, P., Morrison, C. E. and Scott, J. H.
(1963) American Journal of Medicine, 35, 67.
2. Benator, S. R. (1978) Proceedings of the 8th International conference on
sarcoidosis and other granulomatous disorders, pp. 508-513.
3. Sartwell, E. and Edwards, L. B. (1974) American Journal of Epidemio-
logy, 99, 250.
4. Cummiskey, J. and Dean, G. (1979) Journal of the Irish Medical
Association, 72, 500.
5. British Thoracic and Tuberculosis Association (1969) Tubercle, 50,
211.
6. Anderson, R., Brett, G., James, G. and Siltzbach, L. (1963)
Medicina Thoracalis, 20, 152.
7. Hall, G., Naish, P., Sharma, O. P., Dee, W. and James, D. G.
(1969) Postgraduate Medical Journal, 45, 241.
8. Honeybourne, D. (1980) British Journal oj Diseases oj the Chest, 74,
63.
9. Israel, H. L. and Washburne, J. D. (1978) Proceedings of the 8th
International Conference on sarcoidosis, Cardiff.
10. Cummiskey, J. and Keelan, P. (1979) Journal of the Irish Medical
Association, 72, 507.
11. Siltzbach, L. E., James, D. G., Neville, E. et al. (1974) American
Journal of Medicine, 57, 847.
12. Edmondstone, W. M. and Wilson, A. G. (1984) Thorax, 39, 704.
13. James, D. G. (1976) Annals of the New York Academy of Sciences, 278,
321.
|
PMC005xxxxxx/PMC5371162.txt | Quinine, Willow Bark and Thomas Bewick
Peruvian bark was brought to Spain in 1636 and its
ingredient, quinine, was later named after the fourth
Countess of Cinchona, wife of the Viceroy of Peru. The
fame of the medicinal properties of the powder derived
from the bark spread rapidly, but its price was so high
that worthless astringent substitutes became common[l],
Pomet comments that when introduced to France it was
'in such vogue as to be sold weight for weight at the price
of gold'[2]. In England it was not included in the
Pharmacopoeia Londinensis until 1677; at a time of intense
anti-Catholic feelings its popular name of Jesuits' powder
had inevitably aroused suspicion. The common claim,
however, that Cromwell refused treatment with the
'tainted source of the Popish powder'[3], is now thought
to have no foundation. After doubts and setbacks it
became clearer that quinine was a specific drug for the
true 'marsh agues or intermittents', rather than for all
febrile illnesses.
During the eighteenth century the imported bark
remained costly, and an indigenous substitute was
sought. In 1763, the Reverend Edmund Stone presented
'An Account of the Success of the Bark of the Willow in
the Cure of Agues', to the Royal Society[4], He described
how he 'accidentally tasted it and was surprised by its
extraordinary bitterness, which raised the suspicion of its
having the properties of Peruvian bark. As this tree
delights in a moist and wet soil where agues abound, the
general maxim that natural maladies carry their cures
with them was so very appropriate that I could not help
applying it; and that this was the intention of Providence
I must own had some little weight with me'. Stone had
special success in treating rheumatic fever. Many years
later salicin was isolated from willow bark, and eventually
aspirin was synthesised.
There are many varieties of willow. In 1792 'the
modest and candid Mr James, surgeon of Hoddes-
don'[5], introduced Salix latifolia into practice, and 11
years later another provincial surgeon, Wilkinson from
Sunderland, published a treatise on the broad-leafed
willow[6], As a surgeon he explained that his interest was
included in 'that branch of the healing art termed medical
surgery'.
Lest there should be any doubt about his subject he
employed a local engraver in Newcastle-upon-Tyne to
illustrate a branch of the tree 'sufficiently accurate to
enable anyone to ascertain this species from others of the
same genus'. The engraving was hand-coloured and
forms the beautiful frontispiece of this otherwise modest
book. The engraver was Thomas Bewick. Bewick's ledger
records that the work was undertaken during the week
ending 28th August 1802, and was charged at 15
shillings[7].
The engravings of Thomas Bewick and his workshop
apprentices in Newcastle changed the face of illustration,
bringing a new richness and subtlety to the art. His
delicate wood-engravings, worked on the end-grain of
box-wood, are best known from illustrations in his books
on quadrupeds, British birds, and the fables of Aesop.
But he executed more work on copper and silver than on
wood, mostly for commercial purposes in making bank
notes and bills. The frontispiece of the broad-leafed
willow was made from a metal plate and then hand-
coloured.
Though Bewick had doctors as friends and thought
Continued on page 178
Journal of the Royal College of Physicians of London Vol. 19 No. 3 July 1985
173
Continued from page 173
highly of the medical profession[8], few of his illustrations
have medical associations. He made a frontispiece for a
book on diseases of horses, by another Wilkinson[9], and
Bewick's apprentices engraved the illustrations for^4 New
Family Herbal by Thornton, in 1810[10].
In commissioning a local engraver to provide the
frontispiece for his small treatise, Wilkinson was not in a
position to appreciate the full significance of the illustra-
tion; nor was he able to anticipate that an extract from
willow-bark provided the incentive for the synthesis,
some 70 years later, of one of the most widely used of all
therapeutic agents, the salicylates.
George Wilkinson's small book, with its frontispiece by
Thomas Bewick, is available in the College library. It
contains two special features: a dedication inscribed by
the author to the President and Fellows, and the insertion
of some pressed broad-leafed willow leaves. Bewick's
works are well represented in the library; there are two
separate editions of both A General History of Quadrupeds
and The History of British Birds. Thornton's New Family
Herbal (1810), the illustrations for which were engraved
by Bewick's apprentices, is also included.
In the College collection is the well illustrated and
handsome folio first edition of Pierre Pomet's Histoire
Generale des Drogues (1694). This first French edition was
translated into English (1712) and published with the title
Compleat History of Druggs; Pomet was described as the
'chief druggist to the late King Lewis (sic) XIV'. The
anonymous translator dedicated the work to Sir Hans
Sloane. It became a popular work and is often regarded as
the first comprehensive materia medica in English. The
College's English edition (1748) is the fourth, in which
the editorial approach is dubious, for it had been
amended and rendered 'less obscure' by the self-styled
'Sir'John Hill, opportunist and quack, a man referred to
by Dr Johnson as ingenious but having no veracity.
References
1. Bruce-Chwatt, L. J. (1982) Transactions of the College of Physicians of
Philadelphia, series 5, vol 4, pp.98-121.
2. Pomet, P. (1712) ^4 Compleat History of Druggs, London: Bonwicke.
3. Copeman, W. S. C. (1964) A Short History of Gout and the Rheumatic
Diseases, Berkeley: University of California Press.
4. Stone, E. (1763) Philosophical Transactions of the Royal Society, 53,
195.
5. James, S. (1792) Observations on the Bark of the Particular Species of
Willow, London.
6. Wilkinson, G. (1803) Experiments and Observations on the Cortex Salicis
Latifoliae, or Broad-leafed Willow Bark, illustrated' by a coloured
plate. Newcastle-upon-Tyne.
7. Bain, Iain, Personal communication.
8. Bain, Iain (ed) (1975) A Memoir of Thomas Bewick, written by himself,
London: Oxford University Press.
9. Wilkinson, William (1818) A Treatise on Two of the most important
Diseases which attack the Horse, Newcastle-upon-Tyne: Walker.
10. Thornton, R. J. (1810) ^4 New Family Herbal, London: Phillips.
D. D. Gibbs
?X
178 Journal of the Royal College of Physicians of London Vol. 19 No. 3 July 1985
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PMC005xxxxxx/PMC5371169.txt |
==== Front
World J PsychiatryWJPWorld Journal of Psychiatry2220-3206Baishideng Publishing Group Inc jWJP.v7.i1.pg110.5498/wjp.v7.i1.1ReviewIdentity and schizophrenia: Who do I want to be? Seeman Mary V Mary V Seeman, Department of Psychiatry, University of Toronto, Toronto, ON M5P 3L6, CanadaAuthor contributions: Seeman MV contributed to the manuscript.
Correspondence to: Mary V Seeman, MD, Professor, Department of Psychiatry, University of Toronto, 260 Heath St W. Toronto, ON M5P 3L6, Canada. mary.seeman@utoronto.ca
Telephone: +1-416-4863456
22 3 2017 22 3 2017 7 1 1 7 27 10 2016 7 12 2016 2 1 2017 ©The Author(s) 2016. Published by Baishideng Publishing Group Inc. All rights reserved.2016Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/Many individuals with schizophrenia have occasional difficulty defining both to themselves and to others who they truly are. Perhaps for this reason they make attempts to change core aspects of themselves. These attempts may be delusional, but are too often unjustly dismissed as delusional before the potential value of the change is considered. Instead of facilitation, obstacles are placed in the way of hoped-for body modifications or changes of name or of religious faith. This paper discusses the various changes of identity sometimes undertaken by individuals with schizophrenia who may or may not be deluded. Ethical and clinical ramifications are discussed. The recommendation is made that, when clinicians respond to requests for help with identity change, safety needs to be the main consideration.
SchizophreniaIdentityBody modificationReligious conversionName change
==== Body
Core tip: Everyone tries at times to change aspects of their identity. When people with schizophrenia do it, it should not necessarily be interpreted as delusional, but safety issues need always to be kept in the foreground.
INTRODUCTION
Schizophrenia has been referred to as an “I am” illness[1], meaning that this disorder affects an individual’s core identity, the qualities, characteristics and continuities that distinguish one person from another. Identity, however, is never static and, particularly in the context of schizophrenia, it has been associated with fluidity and characterized by inconsistent autobiographical recall and changes in self-representation over time[2-4]. The appreciation of a sense of self has been reported as deficient in this illness[5-8]. This is illustrated in a study by Scharfetter[9]. Persons with schizophrenia, when administered a standardized questionnaire about identity, endorsed items such as: “I didn’t know who I was”, “My ancestry changed”, “I often had to look in the mirror”, “I thought I had children”, “I had to say repeatedly “I am who I am”, “My body or parts of it changed”, “My sex changed”. They showed an imprecise awareness of the continuity over time of their body, personal history, and social function.
Given a hypothesized fluidity of self-perceived identity, it is perhaps to be expected that some patients with schizophrenia, once over the acute stage of illness, might want to change their external appearance to conform to a changed self-image[10]. They might also want to re-invent other aspects of who they perceive themselves to be: Their origins, their name, their faith. Reported examples of identity transformations in the schizophrenia literature include: Becoming a vegetarian[11], changing religion[12,13], acquiring identity-changing tattoos and body piercings[14], seeking rhinoplasty[15], changing names[16], and changing genders[17-19]. The question with which clinicians are faced is whether such seemingly abrupt identity changers are signs of psychotic exacerbation, decisions made on delusional grounds, or whether individuals with psychosis, like everyone else and for identical half-rational, half-irrational reasons, occasionally change diets and appearance, convert from one religion to another, and, at times, change genders. The clinician has to determine whether a sudden transformation of self-representation in a person with pre-existing psychosis calls for hospitalization or, instead, whether the person should be referred, as appropriate, to nutritionists, plastic surgeons, chaplains, or gender identity clinics? Because clinicians are often uncertain as to how best to respond to requests for assistance with proposed changes of this nature, I undertook a review of the literature on identity changes in the context of schizophrenia.
METHOD
My search strategy was to pair words representing aspects of identity (name, body, religion, dress, food, gender, ethnicity) with schizophrenia or psychosis in the multidisciplinary Google Scholar database. This yielded 200 abstracts, of which 60 appeared relevant to my purpose. Searching the references of these 60 papers, I found 15 further relevant papers. I will first discuss the various changes of identity reportedly undertaken by individuals with schizophrenia and subsequently I will address ethical and clinical ramifications.
NAME CHANGE
Ethnicity, religion, ancestry, gender, social class, birth order, physical appearance, time and place of birth all contribute to what is called identity, and most of these contributions can be reflected in a person’s name[20-22]. A name change is therefore a powerful way to assume a new identity. Changes of name can act as connections[23], a way for instance, of blending in with a new environment, of marking a valued affiliation or being reborn into a new religion. Sometimes, however, changing one’s name can serve as a separation. It can be a way to hide one’s former identity, to repudiate one’s ancestry. These different motivations apply to persons with schizophrenia as to anyone else with the added possibility that the wish to hide a previous identity in this population stems from paranoia and originates in delusional thinking. In a 12-year retrospective study of patients attending a psychiatric unit (31% of whom suffered from schizophrenia), it has been reported that 0.7% had at some time in life adopted an alias[24]. In another study, Völlm et al[25] found that up to one fifth of psychiatric offender patients had changed their names at least once, motivated by the wish to either consolidate or break family ties, make a fresh start in life, or simply to discard a disliked name. Persons with psychosis, more than other patients, gave idiosyncratic reasons for changing their name, and the names they selected were characterized by being relatively famous names or names that carried symbolic significance. Völlm et al[25] note that the reasons given for name changes by patients in their sample with a diagnosis of schizophrenia sounded as if they might be delusional “It was something mysterious, sinister. Sinister, mysterious name” (25; p. 46).
PHYSICAL APPEARANCE
It is generally acknowledged that facial features (eyes, nose, lips, ears, skin, hair) are fundamental indices of identity and human beings throughout history have attempted to enhance or camouflage these features by cosmetics, depilation, piercing, ornamentation, wigs, head coverings, veils, tanning, bleaching, dreadlocks, crew cuts, and plastic surgery.
With respect to tattoos, a higher than average prevalence of skin markings has been found among young adults who use mental health services[26,27]. In an early study of visible tattoos on a psychiatric ward, Birmingham et al[28] reported a 30% rate of schizophrenia. The percentage would be much lower today because, in many parts of the world, tattoos have become quite commonplace. An example of a tattoo motivated by a delusion is provided in Campo et al[29] where a man with a tattoo states, “I thought I lived with Satan and therefore I needed his sign on my back” (29; p. 166). For the most part, however, the literature considers tattoos as non-delusional attempts to declare a new identity or to rebel against an old one. Like names, they can be marks of affiliation or differentiation or they can merely be efforts to stay in vogue with current fashion[30]. Because they are considered to represent “toughness”, tattoos often increase self-confidence and feelings of empowerment, especially when they are strategically situated so that their visibility is under the control of the wearer[31,32]. This can serve important morale-boosting purposes in persons with schizophrenia. Whether people with schizophrenia choose specific configurations or themes for their tattoos has not been investigated.
The treatment of schizophrenia can sometimes transform a person’s appearance, weight gain being a prime example[33] and the illness itself can significantly change a person’s voice, accent, and language use, markedly affecting the responses of others[34-37] and, therefore, secondarily, influencing one’s self-evaluation.
Drastic changes in appearances have been reported in schizophrenia[29], often precipitated by major life events[38] and sometimes achieved through plastic surgery. Cosmetic surgery for nose or breast is widespread in the general population, but actively seeking it is particularly common in those with body dysmorphic disorder[39-41], a condition that shows some overlap with schizophrenia[42-44]. While some common changes, such as hairstyles[45], are frequent and ubiquitous and harmless, the drive to change appearance can sometimes have dangerous results[46]. Major self-mutilation, defined as individuals amputating their limb or their genitals or removing an eye, has been strongly associated in the literature with the presence of psychosis[47,48].
Body modifications include taking hormones or undergoing sex-reassignment surgery. A recognizable minority of individuals with gender identity disorder are said to suffer from a psychotic illness[17-19,49-51]. Gender identity disorder patients who are psychotic are often denied gender surgery in the same way that people with psychosis were once denied bariatric surgery for morbid obesity[52,53]. Decisions on what is right under these circumstances can be very difficult for clinicians.
CONSUMMATORY BEHAVIORS
Humans use belongings and personal effects to create and recreate an identity and to show themselves to others in a selective fashion[54]. Personal identity is often expressed in what one owns, how one dresses, where one lives, and even what one eats. The decision to become a vegetarian, for example, is taken by a large percentage of the population. It is usually seen as the mark of an animal rights devotee or a fitness enthusiast, but obsessive attention to diet can, at times, represent a form of psychotic eating disorder[55-58].
Dress, a well-recognized symbol of identity[59,60], is often described as idiosyncratic in individuals with schizophrenia[61-63]. A way of dressing that strikes others as odd may be deliberate (as a form of identification with a particular subculture or a renunciation of a previous identification) or it may simply be the result of economic constraints and needing to make do with second hand clothing[64]. Dishevelment can also result from apathy and negative symptoms and cognitive deficits. In addition, problems with thermal regulation leading to redundant clothing have been postulated in schizophrenia[65]. In other words, it cannot be assumed that dressing in an “odd” way is intentional or indicative of wanting to assume an “odd man out” identity. On the other hand, the symbolic self-completion theory[66] proposes that, when people feel incomplete in an identity - persons who are newly homeless for instance - they may deliberately adorn themselves with symbols associated with that identity (rags, layers of clothes, unwashed clothes) in order to more fully embrace the new role and achieve a sense of completeness. This may apply even when the new identity is unwanted.
IDENTITY BY ANCESTRY
Many people nurture a fantasy about being adopted, about having a long lost twin, about their “true” hidden parentage; many renounce their national or ethnic identity and adopt a new one, usually for safety or economic reasons. Many do so for delusional reasons as did John Nash when he renounced his United States citizenship upon developing psychosis[67]. Motives can include a desire to individuate or a desire to assimilate. Identification with an idealized other may be responsible[68]. There is at least one report in the literature of distorted ethnic identity in the context of psychosis[69]. An attempt to change ethnicity is more dangerous than the other changes discussed in this paper because it may arouse political suspicion and potential retaliation.
RELIGIOUS IDENTITY
In the Western world, many contemporary men and women choose, at some point in their lives, to leave the religion of their parents and establish a different religious identity for themselves[70]. They do so for a number of different reasons, rational, emotional, and spiritual[71]. Conversion to a new religion is often experienced as a transformational change, and has been described with vocabulary that is similar to that used to describe an episode of psychosis. Conversion is said, for instance, to give people a new sense of life’s meaning and a new relationship to God[72-77]. Individuals with psychotic illness use very similar terms when they talk about their beliefs, making it difficult to distinguish religious conversion from delusional thinking. In fact, conversion experiences in the context of schizophrenia are not rare[13,78]; individuals with psychosis appear to be attracted, more than others are, to new religious movements[12], perhaps because such movements offer explanation of and salvation from the distress of psychotic symptoms. They have been described as capable of fulfilling emotional needs and stimulating spiritual growth[79]. New religious movements are also, as social communities, more welcoming than traditional religions to relatively isolated persons. Religious delusions have been reported to trigger conversion[80]. Interestingly, in a study of 14 forensic psychiatric patients who had changed faiths[81], one person with a diagnosis of schizophrenia gave as his reason for converting the conviction that his former religion was responsible for fueling his delusions.
LIMITATIONS OF THE REVIEW
This review of the literature skips over many difficulties (such as definitions of identity) and does not mention political, professional, and social class identities. Nor does it discuss personality and behavior changes that can seemingly transform a person, especially in the context of psychotic illness. This paper should be viewed as exploratory, with much important territory left uncovered.
DISCUSSION
The literature suggests that individuals with schizophrenia sometimes make fundamental changes to their identity and sometimes ask clinicians for assistance. It is acknowledged that change decisions can, at times, be grounded in delusional thinking, leaving clinicians in a quandary as to how to respond. Sanati et al[82] argue, however, that not taking a person’s statements at face value constitutes an act of testimonial injustice[83], an unjustified devaluation of a person’s word. Individuals with a diagnosis of psychosis are often exposed to this form of injustice because the term, schizophrenia, is linked in many people’s minds with personal attributes such as irrationality and untrustworthiness. It is well known, however, that decisions and acts can at times, in everyone, be made on irrational grounds; to discredit them a priori, based on a person’s diagnosis, is manifestly unjust. The assumption that a person’s thinking in a given circumstance is affected by having once been deluded about a different matter, may be correct, but may not be. Once a person has been diagnosed with delusions, to subsequently dismiss all their stated beliefs is an example of unfair bias[84,85].
Clinicians, of course, form their opinions about a patient’s credibility on more than the diagnosis and the psychiatric history. They have their own prior opinions about what is believable and what is not. The credibility of patients with schizophrenia who declare, “I’ve decided from now on to take my medication as prescribed” will go unquestioned. This decision will be deemed wise. “I’ve decided to become a vegetarian” may also be met with approval, given that vegetarianism is likely to lead to weight loss, often necessary in individuals with schizophrenia who have gained weight as a result of treatment. But the vegetarian decision may be appraised differently if the clinician does not believe in it[86].
Clinicians’ responses also depend on what they perceive to be the logic behind the intended change. For instance, wanting to change one’s name because the original name is hard to pronounce[87] makes sense to a clinician, but wanting to be renamed Clark Kent “Because I am able to unleash supernatural powers”, will arouse alarm. Psychiatrist and philosopher, Karl Jaspers (1883-1969) wrote, “the mentally ill person surely has as much right to be illogical as the healthy one”[88], and this is worth keeping in mind, but what is more important than logic is safety.
Most clinicians would agree that individuals with schizophrenia should be as free as anyone else to engage in acts of self-redefinition[89], but the line is drawn where safety is called into question. One important aspect of safety is reversibility. Shaving off one’s hair to look like a favorite movie actor makes for a decisive change in one’s appearance, but hair grows back. Another matter altogether is identifying with and wanting to emulate a film star who has undergone a mastectomy. Such a body modification would be, for all intents and purposes, permanent, a form of self-mutilation that leaves an irreversible mark[90].
How then, should clinicians react to requests for help in changing identity? There are no hard and fast rules; the following are suggestions based on the limited literature: (1) the clinician should not assume that the request is delusional and signals illness deterioration; (2) the clinician should not discredit or dismiss the request out of hand; (3) asking about the reasons behind the request is always in order. Staying actively interested encourages the patient to discuss motivations at length; (4) risk assessment should be carried out after considering the person’s track record, the person’s demonstrated knowledge about the choice she or he is making, and the coherence of the argument presented; (5) self-reflection is important. The clinician should try to be consciously aware of personal biases with respect to the person, to the nature of his/her illness, and to the choice being made; (6) the clinician must be able to recognize the effects of age and culture on choices and decisions. In the end, safety has to be the prime consideration; (7) safety issues need to be discussed with the patient; (8) the clinician is advised to inquire about and become familiar with published outcome studies of all proposed body modifications, and to share these results with the patient; (9) a family meeting to expand the discussion and learn about ramifications for family and for community is always useful; (10) recommendations for specialist referral are usually needed; (11) if distance travel is involved in the proposed change, travel precautions need to be ensured[91]; (12) the issue of the patient’s competence to make significant decisions must be assessed; and (13) should there be imminent danger of injury to the patient or to others, hospital treatment must be arranged, against the patient’s will if necessary.
CONCLUSION
When individuals with schizophrenia ask their care providers to assist them in changing their identity through body modification or religious conversion or name change for instance, clinicians have difficulty deciding how to react. This review suggests that whether the request is delusional or not, it should always be taken seriously and the motivation for it thoroughly investigated. There may be risks, however, when acceding to such requests. Safety considerations should always be borne in mind.
Conflict-of-interest statement: The author declares no conflict of interest.
Manuscript source: Invited manuscript
Specialty type: Psychiatry
Country of origin: Canada
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Peer-review started: October 31, 2016
First decision: December 1, 2016
Article in press: January 3, 2017
P- Reviewer: Artiles FJA, Chakrabarti S, Hosak L, Kravos M S- Editor: Qi Y L- Editor: A E- Editor: Wu HL
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World J PsychiatryWJPWorld Journal of Psychiatry2220-3206Baishideng Publishing Group Inc jWJP.v7.i1.pg1210.5498/wjp.v7.i1.12Systematic ReviewsFunctional neuroanatomy in panic disorder: Status quo of the research Sobanski Thomas Wagner Gerd Thomas Sobanski, Department of Psychiatry, Psychotherapy, and Psychosomatic Medicine, Thueringen-Kliniken GmbH, 07318 Saalfeld, GermanyGerd Wagner, Psychiatric Brain and Body Research Group Jena, Department of Psychiatry and Psychotherapy, Jena University Hospital, 07743 Jena, GermanyAuthor contributions: All authors contributed to this paper with conception and design of the study, literature review and analysis, drafting and critical revision and editing, and final approval of the final version.
Correspondence to: Thomas Sobanski, MD, Chief, Department of Psychiatry, Psychotherapy, and Psychosomatic Medicine, Thueringen-Klinken GmbH, Rainweg 68, 07318 Saalfeld, Germany. sobanskit@aol.com
Telephone: +49-3671-541750 Fax: +49-3671-541759
22 3 2017 22 3 2017 7 1 12 33 5 9 2016 16 11 2016 11 1 2017 ©The Author(s) 2016. Published by Baishideng Publishing Group Inc. All rights reserved.2016Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/AIM
To provide an overview of the current research in the functional neuroanatomy of panic disorder.
METHODS
Panic disorder (PD) is a frequent psychiatric disease. Gorman et al (1989; 2000) proposed a comprehensive neuroanatomical model of PD, which suggested that fear- and anxiety-related responses are mediated by a so-called “fear network” which is centered in the amygdala and includes the hippocampus, thalamus, hypothalamus, periaqueductal gray region, locus coeruleus and other brainstem sites. We performed a systematic search by the electronic database PubMed. Thereby, the main focus was laid on recent neurofunctional, neurostructural, and neurochemical studies (from the period between January 2012 and April 2016). Within this frame, special attention was given to the emerging field of imaging genetics.
RESULTS
We noted that many neuroimaging studies have reinforced the role of the “fear network” regions in the pathophysiology of panic disorder. However, recent functional studies suggest abnormal activation mainly in an extended fear network comprising brainstem, anterior and midcingulate cortex (ACC and MCC), insula, and lateral as well as medial parts of the prefrontal cortex. Interestingly, differences in the amygdala activation were not as consistently reported as one would predict from the hypothesis of Gorman et al (2000). Indeed, amygdala hyperactivation seems to strongly depend on stimuli and experimental paradigms, sample heterogeneity and size, as well as on limitations of neuroimaging techniques. Advanced neurochemical studies have substantiated the major role of serotonergic, noradrenergic and glutamatergic neurotransmission in the pathophysiology of PD. However, alterations of GABAergic function in PD are still a matter of debate and also their specificity remains questionable. A promising new research approach is “imaging genetics”. Imaging genetic studies are designed to evaluate the impact of genetic variations (polymorphisms) on cerebral function in regions critical for PD. Most recently, imaging genetic studies have not only confirmed the importance of serotonergic and noradrenergic transmission in the etiology of PD but also indicated the significance of neuropeptide S receptor, CRH receptor, human TransMEMbrane protein (TMEM123D), and amiloride-sensitive cation channel 2 (ACCN2) genes.
CONCLUSION
In light of these findings it is conceivable that in the near future this research will lead to the development of clinically useful tools like predictive biomarkers or novel treatment options.
Panic disorderAnterior cingulate cortexAmygdalaInsulaFunctional magnetic resonance imagingDiffusion tensor imagingVoxel-based morphometryImaging geneticsSerotoninNoradrenaline
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Core tip: This systematic review is focused on the most current research in the functional neuroanatomy of panic disorder. Recent neurofunctional studies suggest that the “fear network”, as proposed by Gorman et al, may need to be amended by additional regions (ACC, insula). Most recently, imaging genetic studies have not only confirmed the importance of serotonergic and noradrenergic transmission in the etiology of panic disorder (PD) but also indicated the significance of neuropeptide S receptor and corticotropin releasing hormone receptor gene variants. Imaging genetics studies are of major importance for the refining of the neuroanatomical model, because genetic risk variants may significantly influence fear network activity in PD.
INTRODUCTION
Panic disorder (PD) is a considerably common psychiatric disease. According to epidemiological studies, six-month prevalence rates have been estimated roughly 1%[1] while lifetime prevalence amounts to 2%-5%[2,3]. PD is characterized by the occurrence of recurrent panic attacks, which are not explained by another psychiatric or medical condition. According to the Diagnostic and Statistical Manual of Mental Disorders (5th edition) panic attacks are sudden episodes of intense fear or discomfort that may be accompanied by palpitations, accelerated heart rate, sweating, trembling, chest pain, nausea or abdominal distress, dizziness, paresthesias, derealization, depersonalization, fear of “going crazy” or even fear of dying[4]. Besides panic attacks, many patients with PD suffer from anticipatory anxiety and maladaptive changes in cognition and behavior resulting in phobic avoidance[5]. PD therefore is often accompanied by agoraphobia and other mental disorders[6].
With regard to the pathogenesis of PD, several cognitive, behavioral and neurobiological theories have been developed[7-9]. Gorman et al[10] introduced a neuroanatomical model that was aimed at integrating the different views of PD as either a biological or a psychological disease. The authors suggested experiments to test their theories. Later, they provided a revised version of their model[11]. Since its inception, this neuroanatomical model has stimulated and greatly influenced research in PD - primarily in the field of neuroimaging studies.
According to Gorman et al[10] three components of PD: (1) acute panic attacks, (2) anticipatory anxiety; and (3) phobic avoidance are located in three specific sites of the CNS: The brainstem, limbic system, and prefrontal cortex. These three neural systems were suggested to be structurally and functionally closely connected, reflecting manifold interactions of the three mentioned clinical features. Hence, according to Gorman et al[10] different treatments for PD and agoraphobia not only affect different symptoms of the illness but also different parts of the brain. Thus, according to the authors, antipanic drugs like tricyclic antidepressants (TCAs) or monoamine oxidase inhibitors (MAOIs) block brainstem-provoked panic attacks; benzodiazepines and relaxation training reduce anticipatory anxiety via the limbic system, and desensitization and cognitive therapies relieve phobic avoidance by influencing functions of the prefrontal cortex. In our opinion it is notable that both psychopharmacological and psychotherapeutic treatments are put on the same level by being conceptualized to act directly on specific neural networks. Therefore the neuroanatomical model proposed by Gorman et al[10] successfully integrates biological and psychological facets of PD.
In the revised version of their hypothesis, Gorman et al[11] suggest that the behavioral symptoms of PD are mediated by a “fear network” in the brain, which is centered in the amygdala and includes the hippocampus, thalamus, hypothalamus, the periaqueductal gray (PAG) region, locus coeruleus (LC), and other brainstem sites. This theory states that patients with PD have a decreased threshold for the activation of the fear network. Excessive activity in this network leads to autonomic and neuroendocrine activation through projections from the amygdala to the brainstem and hypothalamus, resulting in typical PD symptoms. The lateral nucleus of the amygdala receives afferents from cortical regions involved in processing and evaluating sensory information. According to Gorman et al[11] abnormal functioning in these cortical areas could potentially result in the misinterpretation of sensory information (bodily cues), leading to an inappropriate activation of the fear network via misguided excitatory input to the amygdala. The authors propose that activation of the fear network as a result of cognitive misinterpretations could lead to the release of certain neurotransmitters that can cause autonomic behavioral responses related to PD. These responses include an increase in respiratory rate, increases in blood pressure, heart rate, defensive behaviors and postural freezing. Thus, processes at the biological level can directly lead to behavioral symptoms[11]. With regards to drug therapy in PD, Gorman et al[11] not only stated that antidepressants exhibit their antipanic effects via the brainstem, as proposed in their original model[10], but also that therapy with SSRIs might act directly on the limbic system (in particular on the central and lateral nuclei of the amygdala; please see section “The role of serotonin”)[11]. In light of the above, it is intriguing that recent antidepressant medications seem to be able to enhance neuroplasticity mechanisms and adult neurogenesis in the hippocampus and even in the prefrontal cortex[12]. Therefore, due to its unique characteristics, the novel antidepressant agomelatine might also be effective in PD. Preliminary studies have provided encouraging results regarding effectiveness and tolerability of this substance, although it has to be noted that agomelatine is not yet approved for the treatment of PD[13,14].
One of the most important techniques of the neuroanatomical approach to PD is to perform neuroimaging studies on the brain regions that are supposedly active during panic attacks. Today, there are numerous neurofunctional, neurostructural, and neurochemical studies that have demonstrated the significant role of certain structures in the fear network[15-18].
A promising new research method is “imaging genetics”. In this approach genetic information and functional magnetic resonance imaging (fMRI) data are combined in the same subject to define neuro-mechanisms linked to genetic variation[19]. Imaging genetics studies are of major importance for the adjustment and refining of the neuroanatomical model, because genetic risk variants may partly drive fear network activity in PD[15]. The aim of this review is to provide a comprehensive overview of the most significant findings in the field of the functional and structural neuroanatomy of PD. Because of the wide range of this topic, we will focus on recent studies. With regards to prior studies (published before January 2012), we refer to previously published review articles, e.g.[15-18]. However, a complete and exhaustive presentation of all relevant studies is infeasible and certainly beyond the scope of this work.
MATERIALS AND METHODS
We searched the electronic database PubMed for neurostructural, neurofunctional, and neurochemical studies on PD that were published in the period between January 2012 and April 2016. The search was conducted using the following search terminology: “(Panic disorder) and [functional magnetic resonance imaging (fMRI) or diffusion tensor imaging (DTI) or positron emission tomography (PET) or single-photon emission computed tomography (SPECT) or magnetic resonance spectroscopy (MRS) or near-infrared spectroscopy (NIRS) or imaging genetics or serotonin or norepinephrine or noradrenaline or locus coeruleus or dopamine or hypothalamic-pituitary-adrenal (HPA) axis or insula]”. The total number of publications found by the PubMed research was 457 (fMRI: 94; DTI: 2; PET: 5; SPECT: 5; MRS: 11; NIRS: 2; imaging genetics: 21; serotonin: 137; norepinephrine: 19; noradrenaline: 28; locus coeruleus: 3; dopamine: 8; HPA axis: 23; insula: 99). The total number of publications after screening for topic was reduced to 281 (fMRI: 88; DTI: 2; PET: 3; SPECT: 1; MRS: 8; NIRS: 1; imaging genetics: 17; serotonin: 106; norepinephrine: 11; noradrenaline: 4; locus coeruleus: 2; dopamine: 2; HPA axis: 16; insula: 20). The remaining 281 studies were screened for duplicates and finally evaluated for eligibility. Subsequently, a secondary search was conducted that involved a broad review of potential neuroimaging studies by carefully perusing through the citation lists of the retrieved articles. Thereafter, a final screening of the retrieved articles was performed to ensure that the focus of the articles was within the scope of the present review. The literature search was conducted both jointly and independently by the authors (TS, GW). Finally, 76 studies published between January 2012 and April 2016 were included in this review.
RESULTS
Functional neuroimaging studies
Resting state studies: Only a few studies investigated neural functional connectivity pattern using resting state functional magnetic resonance imaging (rs-fMRI) in patients with PD. In one of these studies, Pannekoek et al[20] examined differences in the resting-state functional connectivity (RSFC) of the amygdala, dorsal anterior cingulate cortex (dACC) as well as posterior cingulate cortex (PCC) among 11 patients with PD and 11 healthy controls. They mainly found an increased RSFC between the amygdala and the bilateral precuneus as well as altered RSFC between dACC and frontal, parietal and occipital areas. Lai et al[21-23] reported abnormalities in 30 first-episode medication-naive patients with PD compared to 21 matched controls using different rs-fMRI parameters. They observed right-lateralized altered local fractional amplitude of low frequency fluctuations (fALFF) signal in the occipital cortex, putamen and thalamus in PD patients[21]. ALFF represents the strength or intensity of low frequency oscillations in the BOLD (i.e., blood-oxygen-level dependent) signal. The fractional ALFF represents the ratio of the amplitude in a low frequency band to the amplitude in the total frequency band. The authors also observed abnormal regional homogeneity in the occipital cortex of PD patients compared to controls[22] and decreased inter-hemispheric functional coordination (based on the voxel-mirrored homotopic connectivity) in PD patients in the PCC and precuneus.
Shin et al[24] combined rs-fMRI and magnetic resonance spectroscopy (MRS) techniques to investigate the functional connectivity of the perigenual ACC in 11 patients with PD and whether or not it is mediated by the local gamma-aminobutyric acid (GABA) concentration. Patients showed increased RSFC between ACC and precuneus. This functional connectivity negatively was correlated with the GABA concentration of the ACC.
Provocation studies: As extensively described in a recent review by Dresler et al[15], the most consistent differences between patients with PD and healthy controls yielded by provocation studies were found in the cingular, insular, frontal and brainstem areas. An electronic search of PD provocation studies between 2012 and 2016 returned only one additional investigation. Goossens et al[25] studied the effects of hypercapnia on the brainstem BOLD signal in 15 patients with PD using fMRI. Three brainstem regions were defined as regions of interest (ROI) due to their putative involvement in panic and chemosensitivity: The PAG, the raphe nuclei and the LC. The authors demonstrated increased brainstem activation, i.e., located in the rostral raphe ROI in response to hypercapnia compared to 12 healthy controls and 15 healthy divers. However, a limitation of this study is a rather low voxel resolution, which limits the ability to differentiate between closely situated brainstem nuclei.
Nevertheless, this study provides further support for the significant role of specific brainstem nuclei in triggering panic attacks.
Motor, sensory and cognitive tasks
Investigating auditory habituation by means of fMRI, Pfleiderer et al[26] reported an increased activity of superior temporal and frontopolar cortex in 20 PD patients during the third block of auditory stimulation when compared to 20 healthy controls, as well as a positive correlation of these regions with anxiety measures.
Using fMRI, Wintermann et al[27] studied a sample of 13 patients with PD both with and without agoraphobia, and 13 healthy controls while olfactorily stimulating their senses with stress-related sweat odors as well as artificial odors and non-fearful non-body odors. Although PD patients did not differ from HC regarding their olfactory identification ability, patients showed an increased activation in the superior temporal gyrus, the supramarginal gyrus, and the cingulate cortex for sweat odor caused by ergometric exercise. Presenting sweat odor from the anxiety condition, PD patients showed an increased activation in the inferior frontal gyrus (IFG), which was positively correlated with the severity of the psychopathology. By means of a pH-sensitive MRI strategy Magnotta et al[28] investigated brain pH in 13 PD patients, which has been suggested to play a critical role in PD. Greater activity-evoked (visual flashing checkerboard) T1 rho changes, indicating pH changes in the visual cortex and ACC in patients compared to 13 HC, were detected.
Emotional processing
In order to understand the neurobiological underpinnings of PD, functional neuroimaging studies have often investigated the neurobiological bases of anxiety using paradigms focusing on activation correlates of stimuli with direct diagnostic relevance to PD. For example, panic-related pictures are presented to people suffering from PD to study the neural underpinnings of threat processing in this group[29].
In the present review, studies will be presented divided in paragraphs for the modality of stimulation (i.e., pictorial stimuli, word stimuli, conditioned stimuli).
Emotional processing - pictorial stimuli
By means of fMRI, Gorka et al[30] investigated insular response to unpredictable aversiveness using negative or neutral images selected from the International Affective Picture System in 13 PD patients with comorbid major depressive disorder (MDD). Patients with PD exhibited greater bilateral insula activation to unpredictable aversiveness compared with 19 healthy controls and 9 control patients with MDD only. This study highlights the specific role of the insula in the pathophysiology of anxiety disorders. Wittman et al[31] investigated the neural correlates of the anticipation of agoraphobic situations in 72 PD patients with agoraphobia using agoraphobia-specific and neutral pictures presented with and without anticipatory stimulus. Stronger activations were observed in the bilateral ventral striatum and left insula in patients compared to 72 controls during the anticipation of agoraphobia-specific pictures.
Engel et al[32] used pictures showing characteristic panic/agoraphobia situations to investigate activation differences in 19 PD patients in the predefined ROIs, i.e., prefrontal, cingulate, and insular cortex, and the amygdalo-hippocampal complex. Greater activation in PD patients than in 21 controls was detected in the insula, left IFG, dorsomedial prefrontal cortex (DMPFC), the left hippocampal formation, and left caudatum, when panic-related and neutral scenes were compared.
In a very recent fMRI study, Feldker et al[29] presented panic-related and neutral visual scenes to 26 PD patients to study the neural underpinnings of threat processing. Similarly to the results found by Engel et al[32], patients showed hyperactivation in an extended fear network comprising the brainstem, insula, thalamus, ACC, midcingulate cortex and DMPFC for disorder-related vs neutral scenes, compared to 26 healthy controls. No significant amygdala differences between groups could be found. Subjective levels of anxiety significantly correlated with brainstem activation in PD patients.
Interestingly, Liebscher et al[33] very recently showed that successful cognitive-behavioral therapy (CBT) led to a greater decrease in anxiety symptoms and associated reduction in bilateral amygdala activation during processing of agoraphobia-related pictures compared to the patients receiving antidepressants and a wait-list control group.
Four recent studies investigated the neural activation in patients with PD during processing of emotionally neutral and disorder-specific faces. Ottaviani et al[34] studied amygdala response to masked fearful faces as well as only to faces containing low range of spatial frequencies (LSF) in PD in 13 PD patients. In contrast to 15 healthy controls, patients failed to show bilateral amygdala activation to fearful masked faces vs neutral faces. LSF faces did not elicit an amygdala response in patients or controls. Demenescu et al[35] examined amygdala fMRI activation and its connectivity with the medial prefrontal cortex during emotional face perception in 14 patients with PD and 17 patients with social phobia. Patients with PD, but not those with social phobia showed hypoactivation in the amygdala and lingual gyrus during perception of angry, fearful, happy and neutral faces, compared to 16 healthy participants. The authors also found a positive correlation between degree of anxiety symptoms and functional connectivity of the amygdala to dACC and to DMPFC during perception of fearful faces.
Petrowski et al[36] investigated the neural activation of emotionally neutral faces and places in 15 PD patients with agoraphobia. Patients showed decreased neural activation in the occipital cortex and the cerebellum, and increased activation in the precuneus compared with 15 healthy controls.
Poletti et al[37] applied in their fMRI study a face-matching paradigm to 18 outpatients with PD to study the neural correlates of implicit emotional processing of fearful or angry affective facial expressions. The authors performed a correlational analysis and showed a positive relationship between anxiety sensitivity and fMRI activation during emotional processing in the a-priori defined ROIs, i.e., the DMPFC, ACC and insula, but not in the amygdala.
Emotional processing - word stimuli
Only two recently published studies (from 2012 till 2016) used word stimuli to investigate altered functional activation in PD patients.
In an fMRI study with 20 PD patients, Dresler et al[38] applied an emotional Stroop task with panic-related and neutral words. On the behavioral level, PD patients showed a significant emotional Stroop effect (panic-related compared to neutral words), which, on the neural level, was accompanied by increased BOLD signal in the left IFG compared to 23 healthy controls. van Tol et al[39] used fMRI to examine neural activation during the performance of an emotional word encoding and recognition paradigm in 51 patients with MDD, 59 patients with comorbid MDD and anxiety, and 56 patients with PD and/or social anxiety disorder without comorbid MDD. Both groups of patients, i.e., with MDD and PD showed a common hyporesponse in the right hippocampus during positive word encoding compared with 49 control subjects. During negative encoding, altered insular, amygdala and ACC activation was observed in depressed patients only. During positive word recognition, only PD patients showed increased IFG activation.
Emotional processing - conditioned stimuli
In an fMRI study by Tuescher et al[40], 8 PD patients, 8 posttraumatic stress disorder patients and 8 healthy controls learned to associate specific neutral stimuli with either a safe or threat context indicating the possibility of an electrical shock. In comparison to the other two groups, PD patients demonstrated significantly less activation in response to the “threat” condition and increased activation in response to the “safe” condition in the subgenual cingulate cortex, ventral striatum, amygdala, and in the PAG.
Lueken et al[41] investigated neural activation patterns in 60 patients with PD and agoraphobia during a fear conditioning task. Differential conditioning was associated with enhanced activation of the bilateral IFG, whereas simple conditioning and safety signal processing were related to increased midbrain activation in patients with PD and agoraphobia vs 60 healthy controls. Anxiety sensitivity was positively associated with the magnitude of midbrain activation.
In a randomized, controlled, multicenter clinical trial Kircher et al[42] investigated the effects of cognitive behavioral therapy (CBT) and brain activation during fear conditioning in 42 medication-free patients with PD and agoraphobia. After CBT, patients revealed reduced activation for the conditioned response (CS+ > CS-) in the left IFG compared to control subjects, which was correlated with reduction in agoraphobic symptoms. Patients also demonstrated increased functional connectivity between the IFG and amygdala, insula, as well as ACC after CBT.
Emotional processing - internal triggers of fear
The hypothesis of an increased attentional focus in PD towards bodily symptoms and their neural correlates was tested in a study by Pfleiderer et al[43] in a group at risk for PD, i.e., 24 healthy female students with high levels of anxiety sensitivity. In contrast to 24 females with normal levels of anxiety sensitivity, the highly anxiety-sensitive group reported higher arousal scores and higher activation during interoception (attention on the heartbeats) in a network of cortical, i.e., frontal, motor regions and subcortical brain regions, i.e., claustrum, thalamus, amygdala, parahippocampus that overlaps with known fear circuitry structures.
Brief summary: Even if not always consistent, functional studies suggest abnormal activation mainly in an extended fear network comprising brainstem, insula, anterior and midcingulate cortex and lateral as well as medial parts of the prefrontal cortex. Interestingly, differences in amygdala activation were not as consistently reported as one would predict from the hypothesis of Gorman et al[11].
Structural neuroimaging studies
Previous structural neuroimaging data in PD using a manual tracing of ROI as well as using an automated voxel-based morphometry (VBM) technique showed changes in total and in gray matter (GM) volume in limbic structures, e.g., in the amygdala, hippocampus, in frontal, cingulate and temporal cortical areas, in the basal ganglia, and in the brainstem structures, such as midbrain and rostral pons (comprehensive review of structural findings in PD until 2012 by e.g.[15,44]). Regarding the latter finding, Fujiwara et al[45] also showed increased midbrain volume in 38 PD patients compared to the control group of 38 matched healthy subjects.
With regard to subcortical structures, Kartalci et al[46] reported that 27 patients with PD had significantly smaller pituitary volumes compared to 27 healthy subjects. In particular, patients with agoraphobia had a significantly smaller pituitary volume than patients without agoraphobia. In addition, Terlevic et al[47] observed decreased hypothalamic volumes in 12 patients with generalized anxiety disorder, but not in those with PD (11 patients) compared to 21 healthy controls.
A cortical area often studied in PD and known for its reciprocal connections with the amygdala is the orbitofrontal cortex (OFC). Atmaca et al[48] detected significantly smaller left OFC volumes in 20 PD patients compared with 20 healthy controls. Lai et al[49] showed in 30 first-episode, drug-naive and late-onset PD patients lower GM volumes in left OFC, as well as in the left IFG, left superior temporal gyrus and in the right insula compared to 21 healthy controls. Na et al[50] showed decreased GM volume in the left medial OFC in only 12 patients with both PD and agoraphobia compared to 22 healthy control subjects, but not in the 10 patients with PD and without agoraphobia nor in in the total sample.
Considering the white matter (WM) abnormalities in PD, the first study to investigate the WM integrity by applying the DTI technique revealed higher structural integrity in terms of greater fractional anisotropy (FA) values in the cingulum bundle[51]. In a recent study with 30 first-episode, medication-naive and late-onset PD patients, Lai et al[52] showed reduced integrity in WM tracts of the right inferior fronto-occipital fasciculus (IFOF), left body of corpus callosum and left superior longitudinal fasciculus (SLF) when compared to 21 controls. Kim et al[53] reported no significant difference in WM integrity between 26 PD patients and 26 healthy controls. However, the authors showed increased right-lateralized FA in posterior thalamic radiation, posterior and superior corona radiata, SLF, and sagittal stratum in catechol-O-methyltransferase (COMT) AA/AG genotype group compared to GG genotype in PD.
Kim et al[54] reported decreased FA in frontal WM and the genu of the corpus callosum in 36 short-term medicated patients with PD compared to 27 healthy controls.
Furthermore, increased structural integrity in the internal capsule, corpus callosum, superior and posterior corona radiata, thalamic radiations, sagittal stratum, and SLF were detected in 12 PD patients with a suicide attempt compared to 24 PD patients without suicidal attempt[55]. However, due the lack of a healthy control group, this result is difficult to interpret.
Very recently, Lai et al[56] compared 53 medication-naive patients with 1st-episode PD, 53 medication-naive patients with 1st-episode MDD and 54 healthy controls with regard to the WM integrity. The PD group had lower integrity in bilateral superior longitudinal fasciculi and left IFOF when compared to controls, whereas MDD patients revealed reductions in the WM integrity when compared to controls in the bilateral superior longitudinal fasciculi, inferior longitudinal fasciculi, inferior fronto-occipital fasciculi, and corpus callosum. The MDD group had lower WM integrity than the PD group in the left anterior thalamic radiation, left uncinate fasciculus, left IFOF, and bilateral corpus callosum.
Using VBM, Konishi et al[57] demonstrated in 40 PD patients significant volumetric reductions in widespread WM regions including fronto-limbic, thalamo-cortical and cerebellar pathways compared to 40 healthy controls.
One structural imaging study investigated cortical gyrification in PD and detected significant reduction in gyrification in 23 patients with PD in the lateral brain, extending from the fronto-parietal to the temporal areas compared with 33 healthy individuals[58].
Schwartz et al[59] demonstrated a significant relationship between behavioral inhibition and hippocampal structure. Behavioral inhibition in childhood predicted reduced hippocampal volumes in adolescents who were offspring of parents with PD or PD with comorbid major depression, suggesting a role of the hippocampus in anxiety disorder. Trzesniak et al[60] was one of the first to use proton magnetic resonance spectroscopy imaging [(1)H-MRSI] to examine possible neurochemical abnormalities in the hippocampus in PD. Compared with 18 controls, twenty-five PD patients demonstrated significantly lower NAA/Cr in the left hippocampus.
Interestingly, Shinoura et al[61] reported in a case report study that damages to the dorsal part of the ACC led to repeated panic attacks, indicating that this structure might play an important pathophysiologic role in PD.
Brief summary of structural findings: Previous and recent neurostructural findings indicate the presences of structural neuroanatomical alterations in PD in multiple cortical, subcortical and brainstem areas. Studies on WM also revealed significant abnormalities in the structural connectivity between these regions.
Neurochemical alterations in PD
The role of serotonin: It is well established that PD responds to drugs that increase serotonergic function, such as certain TCAs, inhibitors of monoamine oxidase (classical MAOIs), selective serotonin reuptake inhibitors (SSRIs), and serotonin-norepinephrine reuptake inhibitors SNRIs[62]. The SSRIs are now generally accepted as the first-line pharmacological treatment for PD[63]. Therefore, there is clear evidence for an important role of serotonin in the pathophysiology of PD that has led to extensive research - predominantly in neuroimaging and animal studies. According to Gorman et al[11] the anxiolytic effect of SSRIs is mediated by at least three mechanisms: (1) inhibitory serotonergic projections from the raphe nuclei downregulate the activity of noradrenergic neurons in the LC[64]. The authors concluded that SSRIs, by increasing serotonergic activity in the brain, have a secondary effect of decreasing noradrenergic activity. This would lead to an amelioration of the somatic symptoms of panic attacks; (2) the projection of the dorsal raphe (DRN) neurons to the PAG is thought to modify defense/escape behaviors. As derived from animal studies, stimulation of the DRN markedly increases serotonin release in the dorsal PAG region, resulting in diminished activity in this brain area[65] associated with reduced defense/escape responses, i.e., reduced propensity for panic-like reactions; and (3) as a third point, Gorman et al[11] state that long-term treatment with an SSRI may reduce hypothalamic release of corticotropin-releasing factor CRF[66]. CRF, which leads to adrenal cortical production of cortisol, is also a neurotransmitter in the CNS and has been shown to increase fear in preclinical models[67]. CRF enhances activity of the LC, when administered directly into the brain[68]. Furthermore, as stated by Gorman et al[11] SSRIs seem to have an effect on the central nucleus of the amygdala itself. Serotonergic neurons originating in the dorsal and medial raphe nuclei project directly to the amygdala via the medial forebrain bundle[69]. Moreover, serotonergic neurons modulate sensory input at the lateral nucleus of the amygdala, inhibiting excitatory inputs from glutamatergic thalamic and cortical pathways[70]. According to Gorman et al[11] this might be one of the major mechanisms for the anxiolytic action of the SSRIs.
Neumeister et al[71] used PET to study serotonin type 1A (5-HT1A) receptor binding in 16 patients with PD and 15 matched healthy controls. PD patients showed lower values in the anterior and posterior cingulate cortex (PCC) as well as in the raphe nuclei. For the first time, this study provided in vivo evidence for the involvement of serotonin type 1A receptors in the pathophysiology of PD. Nash et al[72] performed a 5-HT1A receptor binding study in PD patients at different stages of therapy. Nine drug-naive patients with PD, 7 patients who had recovered on SSRI medication and 19 healthy volunteers underwent a single PET scan. In untreated patients, both presynaptic and postsynaptic 5-HT1A receptor binding was reduced predominantly in the raphe nuclei, OFC, temporal cortex and amygdala. In recovered patients, presynaptic binding was also reduced, but there was no significant reduction in postsynaptic binding. Maron et al[73] investigated the binding of the serotonin transporter (SERT) in patients with PD by SPECT. The authors reported a significant decrease in SERT binding in the midbrain, in the temporal lobes and in the thalamus in 8 acute PD patients, but not in 8 remitted patients in comparison to matched controls. Regional SERT binding was negatively correlated with the severity of panic symptoms. In a further SERT binding study of PD, Maron et al[74] reported increased binding potential of the serotonin transporter in the raphe nuclei and several cortical areas. These findings were observed in male patients, but not in females. The authors concluded that distinctive functioning of the serotonin system in male and female PD patients might underlie the gender-dependent expression of the disease.
Given the fact that several neurochemical studies revealed altered 5-HT function in the raphe nuclei, it is noteworthy that structural abnormalities of this area have also been very recently reported. Šilhán et al[75] detected reduced brainstem raphe echogenicity in 26 patients with PD by transcranial sonography (TCS). TCS of the raphe nuclei indicated the diagnosis of PD with a sensitivity of 64% and a specificity of 73%. These findings are suggestive of structural disintegration of the brainstem raphe in PD, an anatomical region, that has also been assumed to be a biological focus in the pathogenesis of depression[76].
Deakin et al[77] proposed a hypothesis suggesting that different subpopulations of serotonergic neurons in the dorsal and median raphe nucleus through topographically organized projections to different brain regions are involved in the pathophysiology of anxiety and affective disorders. These different subpopulations of serotonergic neurons included: (1) serotonergic neurons within the DNR projecting to the dorsal PAG that inhibit innate panic-/escape-like physiological and behavioral responses; (2) serotonergic neurons within the dorsal raphe nucleus projecting to the amygdala, that facilitate conditioned fear and conflict anxiety-like responses; and (3) serotonergic neurons within the median raphe nucleus that increase stress resilience and mediate antidepressant-like effects. This concept partly overlaps with the model developed by Gorman et al[11]. The Deakin/Graeff hypothesis still is a cornerstone that stimulates most recent research in PD.
Spiacci et al[78] investigated whether or not the enhancement of 5-HT-mediated neurotransmission within the dorsal PAG affects panic-like defensive reactions in rats submitted to a hypoxia challenge. Intra-dorsal-PAG injection of serotonin, a 5-HT1A receptor agonist or a 5-HT2A agonist reduced the number of upward jumps during hypoxia, interpreted as escape attempts. These effects were similar to those caused by chronic, but not acute, intraperitoneal administration of the antidepressant fluoxetine, or acute systemic administration of the benzodiazepine receptor agonist alprazolam. These observations confirm that the dorsal PAG is a key region involved in panic-like defensive behaviors. In a subsequent study, the authors demonstrated that serotonergic neurons of the lateral wings of the DRN (one of the five subnuclei of the DRN) are primarily involved in the mediation of PD-associated responses[79].
While the function of the DRN in the regulation of panic-like defense behaviors is well understood, the median raphe nucleus has received less attention. Generally, evidence derived from animal studies points to a relevant role of this raphe nucleus in the regulation of anxiety, but not of panic. This can be achieved through the serotonergic pathway that rises from the MRN to the dorsal hippocampus[80]. Alternatively, the DRN seems to participate in both anxiety and panic. Interestingly, the regulation of anxiety by the dorsal and median raphe serotonergic pathway is carried out through different target structures - the amygdala, dorsal PAG and ventral hippocampus in the case of the DRN, and the dorsal hippocampus in the case of the median raphe nucleus. Because these structures have different functional profiles, it is conceivable that different aspects of anxiety are underpinned by each of them. In this regard, Gray et al[81] have argued that the amygdala may underpin the neurovegetative arousal and affective components of anxiety, whereas the dorsal hippocampus may regulate cognitive manifestations, such as worry. This suggestion is supported by the reported interaction between the dorsal hippocampus and the prefrontal cortex underpinning fear learning and memory[80,82]. According to a recent study by Ohmura et al[83] the ventral (anterior part in humans) hippocampus may be involved in inappropriate retrieval of fear memory in PD. By microinjection of a 5-HT7 receptor antagonist into a rat’s ventral hippocampus, the expression of freezing behavior - an index of fear memory retrieval - was significantly suppressed. The authors argue that the 5-HT7 receptor might be a target of drug development for the treatment of PD.
Brief summary: A major role of serotonin in the pathophysiology of PD has been deduced from the therapeutic effects of serotonergic drugs. In accordance with this hypothesis, studies on 5-HT1AR and SERT binding have revealed altered and mostly reduced serotonergic activity in the raphe nuclei, orbitofrontal cortex, temporal lobes, ACC and PCC, amygdala, and hypothalamus in patients with PD. In the course of therapy with SSRIs, postsynaptic alterations seem to decline, while the presynaptic changes persist. In addition to these functional alterations structural abnormalities, e.g., disintegration of the raphe nuclei in the brainstem have also been described. Serotonin is synthesized primarily in the dorsal and median raphe nuclei. There is evidence from preclinical studies, that efferent inputs of dorsal raphe neurons may moderate panic-like defensive behaviors by controlling the activity of the dorsal PAG.
Alterations of the noradrenergic system
Much research into the neurochemistry of PD has explored the function of the monoamine transmitter noradrenaline. The noradrenergic system plays an important role by regulating the attentional alerting system that prepares and sustains alertness to process high priority signals[84]. Noradrenergic transmission is closely linked to the serotonergic system and to the HPA axis, and therefore mediates between central arousal and the peripheral physical reactions. According to Gorman et al[11] the response to sensory input for the conditioned stimuli is carried out by amygdalar projections. Efferents of the central nucleus of the amygdala are directed to the LC, resulting in an increase in noradrenaline release and contributing to increases in blood pressure, heart rate, and the behavioral fear response[85]. Recent studies in anxiety disorders and particularly in PD revealed higher baseline noradrenaline secretion and increased reactivity to challenges of the noradrenergic system[86-88]. It has furthermore been suggested that the noradrenergically mediated attentional alerting system is particularly active in states of anxiety[89,90]. The assumption of an important role of noradrenergic transmission in the pathophysiology of PD has recently been confirmed by genetic studies that revealed an association between PD and variation in genes modulating the noradrenergic system, such as the COMT[91], the monoamine oxidase A (MAOA)[92] and the norepinephrine transporter (NET)[93-95] genes.
Brief summary: The noradrenergic system plays an important role by regulating the attentional alerting system, which exhibits increased activity during states of anxiety. Noradrenergic transmission is closely linked to the serotonergic system and to the HPA axis, and therefore mediates between central arousal and peripheral physical reactions. Neurochemical studies have revealed higher baseline noradrenaline secretion and increased reactivity to challenges of the noradrenergic system in patients suffering from PD. Recently, genetic studies have demonstrated that there is an association between PD and variations in COMT, MAOA, and NET genes, thus underlining the high importance of noradrenergic transmission in the pathophysiology of PD.
The role of GABAergic neurotransmission
Benzodiazepines are among the most potent and powerful anxiolytic agents[96]. These drugs act through an enhancement of gamma-aminobutyric acidergic (GABAergic) inhibition targeting the GABA receptor[97]. This fact, along with the results of several neurochemical studies, point towards a major role of the GABA system in the pathophysiology of PD. Thus, anticipatory anxiety and panic attacks might be triggered by a decreased GABAergic inhibition in distinct brain regions. In this light, decreased GABA receptor binding or reduced GABA activity (MRS studies) has been reported mostly in frontal, limbic, temporal and respectively insular regions. However, results are inconsistent, as some authors observed reciprocal effects like increased GABA receptor binding in patients with PD (cf. comprehensive review articles by, e.g.[15,98]). In a recent study, Long et al[99] investigated GABA levels in different cerebral regions by MRS. Eleven PD patients, including five with PD family history, six without PD family history and eight healthy controls participated in the study. The authors observed decreased GABA activity in the ACC/medial prefrontal cortex in PD patients, which tended to be more pronounced in patients with PD family history.
However, some methodological limitations of the abovementioned studies have to be taken in account. Firstly, spectroscopic studies still lack a sufficient image and spectral resolution as well as discriminatory power of ROIs. Secondly, it has not yet been proven that the results are specific for PD. In our opinion it would be advisable to include psychiatric comparison groups. Schür et al[100] pointed out that the inhibitory GABA system is thought to be involved in the etiology of several psychiatric disorders. The authors therefore performed a meta-analysis including a total of 40 MRS studies in seven different psychiatric disorders (n = 1.591). Brain GABA levels were lower in autism spectrum disorders and in depressed - but not in remitted - patients compared with healthy controls. No significant differences in GABA levels were found in PD (n = 81). In conclusion, alterations of GABAergic function in PD are still a matter of debate and also their specificity remains questionable.
Brief summary: The results of several neurochemical studies point towards an involvement of the GABAergic system in the etiology of PD. Decreased GABAergic inhibition was reported in limbic, frontal, temporal, and respectively insular regions. Unfortunately, the findings regarding the GABAergic system are partly inconsistent and may not be specific for PD.
Alterations of glutamatergic neurotransmission
There is some evidence derived from animal studies that an excitatory-inhibitory imbalance might play a role in the pathophysiology of PD[101]. Glutamate is the main excitatory neurotransmitter in the mammalian cortex while GABA is the main inhibitory neurotransmitter. Glutamate is the metabolic precursor of GABA, which can be recycled through the tricarboxylic acid cycle to synthesize glutamate[102]. As has already been stressed in the previous section, some studies point towards decreased activity of the inhibitory GABA system in patients with PD, although results of the available studies are inconclusive. Glutamate deploys its excitatory action via binding with N-methyl-D-aspartate and alpha-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid receptors, which are predominantly located in the cortical and limbic structures[103]. According to animal studies, glutamatergic neurotransmission in the lateral nucleus of the amygdala (LA) is involved in fear-conditioning and extinction[104]. Until now, only a few studies have investigated the possible role of glutamate in PD.
Zwanzger et al[101] studied the effects of cholecystokinin-tetrapeptide (CCK-4)-induced panic on brain glutamate plus glutamine (Glx) levels in eighteen healthy subjects by MRS. The authors reported an increase of Glx/creatine levels in the bilateral ACC peaking at 2-10 min after administration of a challenging task. Moreover, HPA axis stimulation was monitored while a significant increase in plasma cortisol was observed throughout the challenge. Maddock et al[105] investigated changes in glutamate plus glutamine in twenty-one PD patients (thirteen remitted, eight symptomatic) and twelve healthy control subjects. MRS was used to measure Glx changes in the visual cortex induced by visual stimulation. PD patients had smaller Glx responses than healthy control subjects, regardless of whether they were acutely ill or remitted. The authors conclude that their results contradict the assumption of a general upregulation of brain metabolic responses in PD.
Preclinical data have suggested that GABA and glutamate neurotransmission are modulated by the neuropeptide S (NPS) system. NPS receptors are widely distributed in the central nervous system with highest expressions in the cortex, thalamus, hypothalamus and the amygdala[106]. Polymorphisms of the NPS receptor gene might genetically drive altered fear circuit function and therefore increase the risk of PD in humans. Ruland et al[107] performed a study of CCK-4-induced panic on brain Glx levels and enrolled thirty-five healthy volunteers with functional neuropeptide S receptor gene (NPSR1) rs324981 A/T variants. MRS during the challenge revealed significantly lower increases of Glx/Cr levels in T risk allele carriers as compared to AA homozygotes in bilateral ACC. These results of a blunted and possibly maladaptive ACC glutamatergic reactivity in T allele carriers are in accordance with the assumption that the NPS system conceivably plays an important role in the pathophysiology of PD.
Brief summary: Glutamate is the main excitatory neurotransmitter in the mammalian cortex. Preclinical studies have suggested that an excitatory-inhibitory imbalance of the glutamatergic and GABAergic systems might play a role in the etiology of PD. Glutamatergic neurotransmission in the amygdala is thought to be involved in fear-conditioning and extinction. The results of animal studies have further suggested that glutamatergic and GABAergic transmissions are modulated by the NPS system. NPS receptors are widely distributed in the central nervous system with highest expressions in the cortex, thalamus, hypothalamus and the amygdala. In a recent imaging genetic study, blunted glutamatergic ACC response due to CCK-4-induced panic was reported in NPSR1 risk allele carriers.
Imaging genetics
During the past decade, studies on the genetic basis of PD have focused on genes related to classical neurotransmitters, mainly monoamines. More recently, other groups of molecules have been identified, including genes involved in neurodevelopment and synaptic plasticity. More than twenty different genes were reported to confer susceptibility to - or modulate the pathological mechanisms of - PD[108]. Identified genes belong to different biological pathways and implicate inter alia the serotonergic, noradrenergic, neuropeptidergic (e.g., NPS) or glucocorticoid system. Imaging genetic studies, as specified below, are designed to evaluate the impact of genetic variations (polymorphisms) on cerebral function in regions critical for PD. Most of the imaging genetic studies used functional magnetic resonance imaging. Some other studies assessed structural connectivity and structural alterations by DTI and VBM.
Genetic variations of serotonin receptor 1A, SERT, and MAOA
Evidence from preclinical and clinical research, including genetic studies, pharmacological trials and neuroimaging, reveals a substantial impact of the serotonin system and particularly the serotonin receptor 1A (5-HT1AR) on the neurobiology of PD[109,110]. Yu et al[111] performed an imaging genetic study by investigating the impact of 5-HTR1A polymorphism on WM connectivity within the cingulum bundle in PD. For this purpose, 32 patients were examined by DTI. The patients were divided into a CC genotype group and a non CC genotype group (GG/CG genotype group) with regard to the 5-HTR1A rs6295 polymorphism. Tractography revealed significantly increased FA values in the left cingulum bundle in the 5-HTR1A CC genotype group compared to the GG/CG genotype. The extent of this alteration was positively correlated with the severity of symptoms that was assessed by several rating scales. Another target of research is the serotonin transporter (SERT) gene, which is also hypothesized to be involved in the pathophysiology of PD due to its identified polymorphisms[112]. According to Bijlsma et al[113] disturbance of SERT functioning leads to fear learning deficits. In a preclinical study, the authors reported disrupted fear acquisition and a concomitant increase in contextual conditioned startle fear in SERT knockout rats. Kang et al[114] demonstrated that SERT polymorphisms can predict health-related quality of life assessments in patients with PD. They used the 36-Item Short Form Health Survey (SF-36), which is a set of generic and coherent quality of life measures. The sample consisted of 179 patients with PD and 110 healthy controls. Patients with PD showed lowered quality of life in all sub-domains of the SF-36 compared to healthy controls. SERT polymorphisms independently and additively accounted for 2.2% of variation (6.7% of inherited variance). Despite its conceivably significant role in the pathophysiology of PD, no imaging genetic study on the SERT polymorphisms in PD has yet been carried out. Reif et al[115] investigated the impact of a promoter polymorphism in the monoamine oxidase A gene (MAOA-uVNTR) on CBT response and brain activity in fear conditioning in a large controlled multicenter study on 369 patients with PD and agoraphobia. This promoter polymorphism is associated with PD and agoraphobia[116] and also has been demonstrated to influence gene expression and monoamine levels[117]. Carriers of the risk allele (causing higher activity of MAOA) had significantly worse clinical outcome. This was accompanied by elevated heart rate and increased fear during an anxiety exposition task. Moreover, risk allele carriers did not habituate due to repetitive exposure. FMRI with a classical fear conditioning paradigm revealed that the protective allele is associated with increased activation of the ACC upon presentation of the CS+ during acquisition of fear. After treatment, further differentiation between high- and low-risk subjects was observed in the inferior parietal lobes, implying differential brain activation patterns upon CBT. This complex multicenter study has demonstrated that a genetic risk factor for PD and agoraphobia may be associated with poor response to CBT and specific underlying neural mechanisms. The authors emphasize that, in the future, genetic information might help to develop individualized treatment methods.
Brief summary: According to recent studies, SERT polymorphisms are associated with fear learning deficits and lowered quality of life measures in healthy subjects. Imaging genetic studies in PD have demonstrated that there is a significant impact of genetic variations on severity of symptoms (5-HTR1A) and response to CBT (MAOA). DTI revealed higher structural integrity within the left cingulum in patients carrying the 5-HTR1A risk allele. In an fMRI study, PD patients with a MAOA risk allele (causing higher activity of MAOA) exhibited a blunted anterior cingulate response during a classical fear conditioning paradigm. After cognitive behavioral treatment, differential brain activation patterns, primarily in the inferior parietal lobes, were described in high- and low-risk subjects.
Genetic variations of COMT and NET
With regard to the noradrenergic system, the COMT and NET gene polymorphisms are hypothesized to be involved in the pathophysiology of PD. Kim et al[53] studied the effects of the COMT gene polymorphism on WM connectivity in PD by DTI. Twenty-six patients with PD and 26 matched healthy controls were enrolled and underwent genotype analysis for COMT rs4680. No differences in WM connectivity were found between patients and healthy control subjects. However, comparison of COMT AA/AG genotype and GG genotype groups in PD patients revealed increased FA in posterior thalamic radiation, posterior and superior corona radiata, superior longitudinal fasciculus (SLF), and sagittal stratum, all located in the right hemisphere. Symptom severity scores in the COMT AA/AG genotype group were positively correlated with the FA in WM tracts. Inoue et al[118] investigated possible associations of COMT, human TransMEMbrane protein 132D (TMEM132D), and GABA receptor alpha 6 subunit (GABRA6) genotypes in PD patients and healthy controls. The polymorphisms rs4680 in COMT and rs3219151 in GABRA6 showed positive associations with PD. In a second step, the authors examined neurophysiological correlates of emotional function in the following areas: ACC and frontal cortex. In PD patients, fMRI responses in the bilateral ACC were stronger in carriers of the AA genotype vs AC + CC genotype in TMEM132D, and stronger in CT + TT genotype vs CC genotype in GABRA6. A response observed in the medial OFC was stronger in carriers of the CT + TT genotype in GABRA6. These results suggest that TMEM132D, GABRA6, and COMT variants may increase vulnerability to panic. Other genetic variants that have attracted growing interest are the polymorphism of the NET gene. The NET is responsible for the reuptake of norepinephrine into presynaptic nerve terminals. Buttenschøn et al[94] studied different variants located within the NET gene with regard to possible associations with PD. The case-control sample consisted of 449 patients with PD and 279 matched controls. Genotyping revealed 29 single nucleotide polymorphisms. Seven polymorphisms were significantly associated with PD, and the NET gene showed overall evidence for association with the disease. These results indicate that NET gene polymorphisms could be involved in the pathophysiology of PD.
Brief summary: Specific polymorphisms of COMT and NET genes have been demonstrated to be associated with a diagnosis of PD. COMT risk allele carriers suffering from PD seem to exhibit increased symptom severity, accompanied by disturbed WM connectivity in wide-spread areas of the right hemisphere (e.g., posterior thalamic radiation, posterior and superior corona radiata, SLF, and sagittal stratum).
Polymorphism of neuropeptide S receptor 1 gene
As already mentioned in the paragraph “alterations of glutamatergic neurotransmission”, NPS is thought to modulate GABAergic and glutamatergic neurotransmission and therefore might be involved in the pathophysiology of PD by affecting fear circuit function. Domschke et al[119] applied a multilevel approach to explore the role of a NPS receptor (NPSR1) gene variant (A/T) in the etiology of PD. The T allele leads to a 10-fold increase in NPSR expression and NPS efficacy[120]. Domschke et al[119] reported that the T allele was associated with PD in female patients. The T risk allele was also related to elevated anxiety sensitivity, increased heart rate and higher symptom reports during a behavioral avoidance test. During an emotional activation task, T allele carriers showed decreased activity in the dorsolateral prefrontal, lateral orbitofrontal and anterior cingulate cortices. Dannlowski et al[121] studied the effects of the T risk allele on amygdala and PFC function by means of fMRI. Seventy-nine healthy subjects were enrolled and genotyped for (NPSR1) gene variants. The authors reported increased amygdala and PFC responses to anxiety related emotional stimuli in risk allele carriers. Guhn et al[122] measured neural correlates of cognitive emotion regulation in 66 volunteers genotyped for the NPSR1 A/T variant (AA homozygotes vs T allele carriers) by means of an emotional n-back task presented during functional near-infrared spectroscopy scanning. T allele carriers showed a signal increase to negative pictures in the dorsolateral and medial prefrontal cortex (DLPFC and mPFC). The authors considered this activation to be part of an adaptive mechanism to compensate for presumably increased subcortical activity driven by an overactive NPS system. Neufang et al[123] investigated the impact of NPSR1 gene variations in 47 healthy subjects on cerebral activation patterns during a task probing alerting functions (Attention Network Task) using fMRI. In the alerting condition, homozygote TT allele carriers showed higher activation in the right PFC and the LC as compared to the AA/AT group. In a recent study, Domschke et al[124] explored the influence of NPSR1 genotypes on fronto-limbic connectivity within the developing brain. Sixty healthy subjects (8-21 years) were examined by fMRI during presentation of a go/no-go task. In A allele carriers, connectivity between the right DLPFC and the right amygdala was higher in older (≥ 14 years) than in younger (< 14 years) subjects. TT homozygotes (≥ 14 years) showed a reduction of fronto-limbic connectivity between the DLPFC and both the amygdala and the insula. These results suggest a risk-increasing effect of the NPSR1T allele for possible anxiety-related traits via impaired top-down control of limbic structures during adolescence.
Brief summary: The T risk allele of the NPSR1 gene is associated with PD in female patients. This genetic variation is also related to elevated anxiety sensitivity. Moreover, fMRI studies revealed decreased activity in the dorsolateral prefrontal, lateral orbitofrontal and anterior cingulate cortices. Healthy subjects carrying the risk allele exhibit increased amygdala and PFC responses to anxiety related emotional stimuli. During a probe of alerting function, higher activations in the right PFC and the LC region have been observed in healthy risk allele carriers. The results of a very recent study suggest that the NPSR1T allele might be responsible for impaired top-down control of limbic structures during adolescence, therefore increasing the risk for possible anxiety-related traits.
Polymorphisms of corticotropin releasing hormone receptor 1 gene
Another neuropeptide that has attracted attention is the neurotransmitter corticotropin-releasing hormone (CRH), also known as corticotropin-releasing factor (CRF) or corticoliberin. CRH plays a central role in the regulation of the HPA axis. The CRH receptor 1 (CRHR1) triggers the release of the stress response regulating hormone cortisol. Preclinical and clinical studies have indicated that CRHR1 is a possible candidate gene for mood and anxiety disorders[79,125,126]. Weber et al[127] studied different variants located within the CRHR1 gene with regard to possible associations with PD. Genotyping in 531 matched case/control pairs (PD patients and healthy control subjects) revealed 9 single nucleotide polymorphisms (SNPs). Four SNPs were associated with PD. One risk allele (the minor allele of rs17689918) was found to significantly increase risk for PD in females. Subsequently, fMRI was used in 48 PD patients. The risk allele carriers showed aberrant fear conditioning predominantly in the bilateral prefrontal cortex and altered safety signal processing in the amygdala, suggesting existing fear sensitization and sustained fear. Furthermore, in this multilevel study, Weber et al[127] performed an expression analysis of CRHR1 gene. For this purpose, postmortem tissue of 76 deceased individuals obtained from the MRC Sudden Death Brain and Tissue Bank, Edinburgh, United Kingdom, was analyzed. In CRHR1 risk allele carriers, the authors found decreased CRHR1 mRNA expression in forebrains and amygdalae. These results indicate that CRHR1 polymorphisms may play a significant role in the pathophysiology of PD and elucidate the mechanisms by which genetic variation in CRHR1 is linked to this disorder. Aberrant fear conditioning due to CRHR1 variation has been investigated in an earlier study by Heitland et al[128]. One-hundred and fifty healthy volunteers were genotyped for CRHR1 gene polymorphism rs878886. Risk allele carriers showed no acquisition of fear conditioned responses (FPS) to a threat cue in the uninstructed phase. Moreover, these participants exhibited increased FPS. In a recent study, the authors were able to replicate their results in a larger sample (n = 224)[129].
Brief summary: Preclinical and clinical studies have indicated that CRHR1 is a possible candidate gene for PD. In a multi-level study, one allele was found to increase risk for PD in females. Aberrant fear conditioning due to CRHR1 variation was demonstrated in PD as well as in healthy subjects. MRI scans in PD patients revealed that risk allele carriers exhibited aberrant fear conditioning with blunted activations in the bilateral prefrontal cortex. Moreover, during processing of safety cues, patients of this group showed elevated responses in the amygdalae compared to patients without the risk allele. Behavioral and neurofunctional findings of this study indicated an increased fear sensitization and sustained fear in this group. Postmortem analyses in risk allele carriers revealed decreased CRHR1 mRNA expression in the PFC and amygdala.
Polymorphisms of human TransMEMbrane protein TMEM123D and amiloride-sensitive cation channel 2 genes
The human TransMEMbrane protein TMEM123D is expressed in neurons and colocalized with actin filaments that putatively function as a cell-surface marker for oligodendrocyte differentiation[130]. Recent case-control genome-wide association studies have linked variants of the TMEM132D gene with PD, anxiety comorbidity with depression, and anxiety symptom severity in healthy and diseased subjects[131,132]. Haaker et al[133] investigated an independent sample of 315 healthy normal subjects (99 female) of Caucasian descent, of which 132 (22 female) underwent structural MRI assessment. Carriers of a specific risk allele (rs11060369 A homozygotes) showed higher GM volumetric estimates in the left amygdala. Moreover, participants of this group had higher ratings for trait anxiety, behavioral inhibition, and negative affect. Variants of the TMEM123D gene therefore may play an important role in the etiology of PD.
Animal studies have shown that carbon dioxide-mediated fear behavior depends on chemosensing of acidosis in the amygdala through the acid-sensing ion channel[134]. In humans, the amygdala also acts as a chemosensor that detects hypercarbia and acidosis via the amiloride-sensitive cation channel 2 (ACCN2)[135]. Patients with PD exhibit a hypersensitivity to inhaled carbon dioxide, possibly reflecting a lowered threshold for sensing signals of suffocation[136]. Smoller et al[135] examined whether genetic variation of ACCN2 is associated with PD, as well as with amygdala structure and function. The authors conducted a case-control analysis (n = 414 PD cases and 846 healthy control subjects) of ACCN2 SNPs. Two SNPs at the ACCN2 locus showed evidence of association with PD (rs685012; rs10875995). The association appeared to be stronger when PD cases with early-onset (age ≤ 20 years) and with prominent respiratory symptoms were compared with controls. One of the detected PD risk alleles (rs10875995) was associated with increased amygdala volume and heightened task-evoked amygdala reactivity to fearful and angry faces as assessed by fMRI. These results suggest that altered chemosensing of acidosis in the amygdala triggered by ACCN2 gene variants may be involved in the pathophysiology of PD.
Brief summary: Recent association studies have linked variants of the TMEM132D gene with PD. Morphometric analyses in healthy volunteers revealed that carriers of a specific risk allele show increased GM volume in the left amygdala. Moreover, these subjects had higher ratings for trait anxiety, behavioral inhibition, and negative affect. Thus, the results of population genetic studies are confirmed by imaging genetic studies.
Patients with PD exhibit increased sensitivity to inhaled carbon dioxide. The amygdala acts as a chemosensor that detects hypercarbia and acidosis via the ACCN2. In a recent study, it was demonstrated that genetic variation of ACCN2 is associated with PD as well as with amygdala structure and function. Two polymorphisms of the ACCN2 gene showed association with PD. One of the detected PD risk alleles was associated with increased amygdala volume and elevated amygdala reactivity to fearful and angry faces. These results suggest that genetic variation of ACCN2 may be involved in the pathophysiology of PD.
DISCUSSION
Functional neuroimaging studies
The “fear network” proposed by Gorman et al[11] includes the amygdala, the hippocampus, thalamus, hypothalamus, the PAG region, LC, and other brainstem sites. Prior neuroimaging studies have reinforced the role of these regions in the pathophysiology of PD. Additionally, functional alterations in the ACC, orbitofrontal cortex, and insula have been reported (for comprehensive literature overviews, see e.g.[15,16,137]). Recent functional studies suggest abnormal activation mainly in an extended fear network comprising brainstem, anterior and midcingulate cortex, insula, and lateral as well as medial parts of the prefrontal cortex. Interestingly, differences in the amygdala activation were not as consistently reported as one would predict from the hypothesis of Gorman et al[11]. Feldker et al[29] stated that, given the role of the amygdala proposed for the pathophysiology of PD, it seems surprising that amygdala hyperactivation only reached marginal significance. In the same tenor, Etkin et al[138] concluded that “in PD, amygdala hyperactivity appears to be the exception, rather than the rule”. At present, it remains unclear whether aberrant amygdala activation is simply not as characteristic of PD as proposed earlier, whether it is too weak to be detected with common thresholds, or whether specific methodological limitations make it difficult to detect. Indeed, amygdala hyperactivation seems to strongly depend on stimuli and experimental paradigms, sample heterogeneity and size, as well as on limitations of neuroimaging techniques[16,139,140]. However, in our view, it is notable that the amygdala is strongly involved in salience and significance detection in the information stream[141]. Since paradigms with specific fear-evoking stimuli are more difficult to develop for PD patients in contrast to patients with specific phobias, we can speculate that the often observed lack of amygdala hyperactivation in PD might be based on such methodological issues, e.g., using appropriate stimuli and experimental paradigms.
In summary, the alterations of neural activation in patients with PD as reported in past and present studies are somewhat inconsistent. Interestingly, two very recent studies using clear panic-related pictorial stimuli and relatively large sample sizes have put strong emphasis on a specific role of the insula and dACC in the pathophysiology of PD[29,32]. There is growing evidence that the insula, the dACC as well as subcortical structures, such as the amygdala, play a crucial role in salience processing across multiple sensory and cognitive domains by integrating external sensory information with internal emotional and bodily state signals[142]. The latter can be paraphrased with the term interoception, which refers to conscious awareness, emotional processes and behavior related to physiological information arising from the body. This includes processing of proprioceptive and visceroceptive processes such as heart rate, respiration, and blood pressure. Abnormal interoception has been suggested to play a key role in the etiology and maintenance of anxiety disorders[143] in terms of oversensitive perception of somatic sensations and subsequent catastrophizing interpretations. There is evidence to assume that ascending inputs providing information about interoceptive and visceromotor signals related to the current bodily state converge in the insular cortices[144]. In close cooperation with the amygdala, insular activity seems to represent a specific subjective emotional state and the emotive value of external stimuli in terms of salience[145]. Thus, this observation may explain differences between studies on PD patients regarding the amygdala or insula activation, which might be attributed to different subjective emotive values of presented stimuli. Another source of variability that induces potentially different insula/amygdala activation in patients with PD, as well as in control subjects, is the subject-specific state of physiological arousal. Thus, simultaneous acquisition of physiological signals, e.g., heart or respiratory rate in the MR scanner, may potentially explain some part of activation variance in these brain structures.
In addition, the ACC is another brain structure considered to be a key node within the salience network[142] and which has often been observed to show abnormal functioning in PD. It is involved in automatic attentional control as well as in response selection and conflict monitoring[146], thus enabling rapid access to the motor system.
Moreover, the salience network recruits the ventral fronto-parietal network, mainly consisting of the temporo-parietal junction and inferior frontal gyrus (IFG)[147], which is typically activated by infrequent or unexpected behaviorally relevant (salient) events. This recruits additional executive resources to ensure focused attention on task-relevant goals, e.g., to cope with panic-relevant stimuli[148]. This may explain the often observed abnormal activation of the IFG in patients in PD.
In summary, besides the brainstem/midbrain, amygdala and prefrontal cortex, further brain areas such as the insula and the ACC are emerging from recent imaging studies in PD and seem to be of greater importance than originally proposed.
Interestingly, recent studies applying the DTI to investigate the WM connectivity in PD reported abnormal WM integrity in the cingulum bundle as well as in the major fiber tracts, which connect frontal with temporal, parietal and occipital brain regions: The inferior and superior longitudinal fasciculi[149]. This finding is in accordance with the observation of abnormal functional activation in regions of the salience network and of the ventral fronto-parietal network. However, to date only few studies have investigated the integrity of specific WM tracts in patients with PD. Therefore, more studies are required to elucidate the abnormal structural connectivity in PD.
Structural neuroimaging studies
With regard to structural brain imaging studies of GM, volumetric and morphometric changes in limbic structures in frontal and temporal cortical areas, in the basal ganglia, in the pituitary gland and hypothalamus as well as in the midbrain/brainstem structures were reported in recent studies. Similar findings have been described in prior neurostructural studies in PD[15,44,150-152]. The relatively large heterogeneity between studies makes it difficult to relate abnormal GM structure in a specific brain region or a network to PD. The reasons for this inconsistency are manifold. Many of the reviewed studies had the disadvantages of relatively small sample sizes and of comorbid depression or other psychiatric disorders among patients, which may also have an impact on the GM volume estimation.
Neurochemical studies
A major role of serotonin in the pathophysiology of PD has been deduced from the therapeutic effects of serotonergic drugs[62,63]. In accordance with this hypothesis, studies on 5-HT1AR and SERT binding have revealed altered and mostly reduced serotonergic activity in the raphe nuclei, orbitofrontal cortex, temporal lobes, ACC and PCC, amygdala, and hypothalamus in patients with PD[71-74]. In the course of therapy with SSRIs postsynaptic alterations seem to decline, while the presynaptic changes persist[72]. In addition to these functional alterations structural abnormalities, e.g., disintegration of the raphe nuclei in the brainstem, have also been described[75]. Ascending serotonergic projections to cortical and subcortical brain regions have their origin mainly in the dorsal and median raphe nuclei. There is evidence from current animal studies, that efferent inputs of dorsal raphe neurons may moderate panic-like defensive behaviors by controlling the activity of the dorsal PAG[78,79], thus confirming the earlier hypotheses of Deakin and Graeff[77] as well as of Gorman et al[11] on this point. Very recently, serotonergic transmission has been proposed as a possible new drug target for PD, as suggested by the results of a preclinical study, which demonstrated that a 5-HT7 receptor antagonist reduced fear memory retrieval[83].
The noradrenergic system is centrally involved in the regulation of the attentional alerting system[84], which exhibits increased activity during states of anxiety[89,90]. Noradrenergic transmission is closely linked to the serotonergic system and to the HPA axis, and therefore mediates between central arousal and peripheral physical reactions[11]. Neurochemical studies have revealed higher baseline noradrenaline secretion and increased reactivity to challenges of the noradrenergic system in patients suffering from PD[86-88]. Recently, genetic studies have demonstrated that there is an association between PD and variations in COMT[91], MAOA[92], and NET[93-95] genes, thus underlining the important role of noradrenergic transmission in the pathophysiology of PD.
Benzodiazepines are among the most potent and powerful anxiolytic agents[96]. These drugs act through an enhancement of gamma-aminobutyric acidergic (GABAergic) inhibition, targeting the GABA receptor[97]. This fact, along with the results of several neurochemical studies points towards an involvement of the GABA system in the pathophysiology of PD. Decreased GABAergic inhibition was reported in limbic, frontal, temporal, and respectively insular regions[15,98,99]. Unfortunately, the findings regarding the GABAergic system are partly inconsistent and may not be specific for PD[100].
Glutamate is the main excitatory neurotransmitter in the mammalian cortex. It is the metabolic precursor of GABA, which can be recycled through the tricarboxylic acid cycle to synthesize glutamate[102]. Preclinical studies have suggested that an excitatory-inhibitory imbalance of the glutamatergic and GABAergic systems might play a role in the etiology of PD[101]. Glutamatergic neurotransmission in the lateral nucleus of the amygdala is thought to be involved in fear-conditioning and extinction[104]. The results of animal studies have further suggested that glutamatergic and GABAergic transmissions are modulated by the NPS system. NPS receptors are widely distributed in the central nervous system with highest expressions in the cortex, thalamus, hypothalamus and the amygdala[106]. In a recent imaging genetic study, blunted glutamatergic ACC response due to CCK-4-induced panic was reported in NPSR1 risk allele carriers[107]. The results of additional imaging genetic studies on genetic NPSR1 variations will be presented below.
Imaging genetics
During the past decade, studies on the genetic basis of PD focused on genes related to classical neurotransmitters, mainly monoamines. More recently, other groups of molecules have been identified, including genes involved in neurodevelopment and synaptic plasticity. More than twenty different genes were reported to confer susceptibility to - or modulate the pathological mechanisms of - PD[108]. Identified genes belong to different biological pathways and implicate inter alia the serotonergic, noradrenergic, neuropeptidergic (e.g., NPS) or glucocorticoid system. Imaging genetic studies, as specified below, are designed to evaluate the impact of genetic variations (polymorphisms) on cerebral function in regions critical for PD. Most of the imaging genetic studies used functional magnetic resonance imaging. Some other studies assessed structural connectivity and structural alterations by DTI and VBM.
Serotonergic system: According to recent genetic studies, SERT polymorphisms are associated with fear learning deficits[113] and lowered quality of life measures[114] in healthy subjects. Imaging genetic studies in PD have demonstrated that there is a significant impact of genetic variations on severity of symptoms (5-HTR1A)[111] and response to CBT (MAOA)[115]. DTI revealed increased structural integrity within the left cingulum in patients carrying the 5-HTR1A risk allele[111]. In an fMRI study, PD patients with an MAOA risk allele (causing higher activity of MAOA) exhibited a blunted anterior cingulate response during a classical fear conditioning paradigm. After CBT treatment, differential brain activation patterns, primarily in the inferior parietal lobes, were described in high- and low-risk subjects[115].
Noradrenergic system: Specific polymorphisms of COMT[91] and NET[93-95] genes have been demonstrated to be associated with a diagnosis of PD. COMT risk allele carriers suffering from PD seem to exhibit increased symptom severity accompanied by disturbed WM connectivity in wide-spread areas of the right hemisphere[53].
Neuropeptidergic system: The T risk allele of the NPSR1 gene is associated with PD in female patients. This genetic variation is also related to elevated anxiety sensitivity. Moreover, fMRI scans revealed decreased activity in the DLPFC, lateral OFC and ACC[119]. Healthy subjects carrying the risk allele exhibit increased amygdala and PFC responses to anxiety related emotional stimuli[121]. During a probe of alerting function, higher activations in the right PFC and the LC have been observed in healthy risk allele carriers[123]. Results of a very recent study suggest that the NPSR1 T allele might be responsible for impaired top-down control of limbic structures during adolescence, therefore increasing the risk for possible anxiety-related traits[124].
CRH: Another neuropeptide that has attracted attention is the neurotransmitter CRH. CRH plays a central role in the regulation of the HPA axis. Preclinical and clinical studies have indicated that CRHR1 is a possible candidate gene for PD[125,126]. In a multi-level study by Weber et al[127], one allele was found to increase risk for PD in females. Aberrant fear conditioning due to CRHR1 variation was demonstrated in PD as well as in healthy subjects. MRI scans in PD patients revealed that risk allele carriers exhibited aberrant fear conditioning with blunted activations in the bilateral prefrontal cortex. Moreover, during processing of safety cues, patients of this group showed elevated responses in the amygdalae compared to patients without the risk allele. Behavioral and neurofunctional findings of this study indicated an increased fear sensitization and sustained fear in this group. Postmortem analyses in risk allele carriers (brain tissue was obtained from a Tissue Bank) revealed decreased CRHR1 mRNA expression in the PFC and amygdala[127].
Human TransMEMbrane protein (TMEM123D): TMEM123D is expressed in neurons and colocalized with actin filaments that putatively function as a cell-surface marker for oligodendrocyte differentiation[130]. Recent association studies have linked variants of the TMEM132D gene with PD[131,132]. Morphometric analyses in healthy volunteers revealed that carriers of a specific risk allele show increased GM volume in the left amygdala. Moreover, these subjects had higher ratings for trait anxiety, behavioral inhibition, and negative affect[133]. Thus, the results of population genetic studies were confirmed by imaging genetic studies.
Amiloride-sensitive cation channel 2: Patients with PD exhibit increased sensitivity to inhaled carbon dioxide[136]. The amygdala acts as a chemosensor that detects hypercarbia and acidosis via the ACCN2[135]. In a recent multi-level study by Smoller et al[135] it was demonstrated that genetic variation of ACCN2 is associated with PD as well as with amygdala structure and function. Two polymorphisms of the ACCN2 gene showed association with PD. One of the detected PD risk alleles was associated with increased amygdala volume and elevated amygdala reactivity to fearful and angry faces. These results suggest that genetic variation of ACCN2 may be involved in the pathophysiology of PD.
As stated above, the intention of imaging genetic studies is to evaluate the impact of genetic variation (polymorphisms) on cerebral function in regions critical for PD. Given the fact that PD is a multifaceted disease with various pathogenic pathways, the etiological effects of specific polymorphisms shall not be overestimated or generalized. Nevertheless, genetic imaging will help to understand the multitude and the interplay of pathogenic factors in PD. Moreover, future neuroimaging studies will become more sophisticated by including genetically defined patient and control samples. Regardless of the undeniable advantages of imaging genetics, some limitations of the studies presented above have to be mentioned: (1) results of studies in healthy subjects may not or only to some extent be transferable to patients suffering from PD; (2) given the wide variety of genes involved in the pathophysiology of PD, it is still difficult to define homogenous samples and to control for interfering factors; (3) general methodological limitations of neuroimaging studies (e.g., related to paradigms and assessment techniques; please see above) cannot be avoided; (4) identified genes often fail to find replication in larger cohort sets or in different populations; and (5) epigenetic factors and non-coding genomic elements may also play a role in the pathophysiology of PD[153]. Nevertheless, great progress has been made in the field of genetics of psychiatric disorders and by now there is a considerable amount of notable findings. In this light, it is conceivable that in the near future this research will lead to the development of clinically useful tools such as predictive biomarkers or novel treatment options.
Limitations and future directions
This review discusses the recently published neurofunctional, neurostructural and neurochemical alterations in PD.
However, the premise that PD is a single phenotype, might not be accurate. Studies on abnormal brain structure in PD revealed a relatively large heterogeneity of significant findings, which makes it difficult to relate specific regions or tracts with aberrant gray or WM to PD. Additionally, the application of functional MRI did not reduce the heterogeneity of reported findings, even if the brain’s salience network, mainly composed of the amygdala, insula and ACC becomes increasingly important for the understanding of panic attacks.
On the other hand, the new era of imaging genetics provided first insights into the potential etiological heterogeneity of PD. Imaging genetic studies have not only confirmed the importance of serotonergic and noradrenergic transmission in the etiology of PD, but also indicated the significance of neuropeptide S receptor and CRH receptor gene variants. These new insights reveal possible targets for the development of drugs for personalized anxiolytic treatment. Furthermore, appropriate imaging genetics studies may lead to a better understanding of non-response to psychotherapy, e.g., due to the variability of top-down control that the prefrontal/anterior cingulate cortex exerts on the amygdala/hippocampus, as well as on the brainstem in PD[154]. In the future the imaging genetics approach will be of major importance for the further development of the neuroanatomical model, because genetic risk variants may significantly influence fear network activity in PD[15]. Therefore, imaging genetic consortia are necessary to accumulate a sufficient number of functional and structural brain scans, which may allow researchers to detect genome-wide significant loci affecting brain function and structure in PD.
COMMENTS
Background
Panic disorder (PD) is a frequent psychiatric disease. Gorman et al (2000) proposed a comprehensive neuroanatomical model of PD, which suggests that fear- and anxiety-related responses are mediated by a so-called “fear network” which is centered in the amygdala and includes the hippocampus, thalamus, hypothalamus, periaqueductal gray region, locus coeruleus and other brainstem sites. It was further assumed that the serotoninergic system plays a pivotal role in the etiology of PD.
Research frontiers
The main focus of this systematic review was laid on recent neurofunctional, neurostructural, and neurochemical studies. Within this frame, special attention was given to the emerging field of imaging genetics.
Innovations and breakthroughs
Recent functional imaging studies revealed abnormal activation not only in the “fear network” proposed by Gorman et al (2000), but also in additional brain regions such as anterior and midcingulate cortex, insula, and prefrontal cortex. Thus, the so-called “salience” network of the brain becomes increasingly important for the understanding of PD. Advanced neurochemical studies have substantiated the major role not only of serotonergic, but also of noradrenergic and glutamatergic neurotransmission in the pathophysiology of PD. In addition, imaging genetic studies have confirmed the importance of serotonergic and noradrenergic transmission in the etiology of PD and, moreover, have indicated the significance of neuropeptide S receptor and CRH receptor gene variants.
Applications
Genetic imaging studies have revealed that genetic risk variants may significantly affect fear network activity in PD. Thus, the inhomogeneity of neuroimaging findings, as reported in this review, could be partly due to such influences. In future studies these effects will have to be considered carefully. Other practical applications of the genetic imaging approach could be the development of clinically useful tools such as predictive biomarkers or drugs for personalized anxiolytic treatment.
Terminology
All terms that may not be familiar to the majority of the readers are explained at the beginning of each major section.
Peer-review
This is, in summary, an interesting review manuscript aimed to provide a detailed and comprehensive overview of the current research in the functional neuroanatomy of panic disorder. The authors mainly focused on recent neurofunctional, neurostructural, and neurochemical studies about the specified topic. They concluded that it is conceivable that new research advances may lead in the near future to the development of clinically useful tools like predictive biomarkers or novel treatment options.
Conflict-of-interest statement: The authors declare no conflict of interests for this article.
Data sharing statement: As this was a systematic review of published data there were no participants to be approached for informed consent for data sharing. No additional data are available.
Manuscript source: Invited manuscript
Specialty type: Psychiatry
Country of origin: Germany
Peer-review report classification
Grade A (Excellent): A
Grade B (Very good): 0
Grade C (Good): C
Grade D (Fair): 0
Grade E (Poor): 0
First decision: October 20, 2016
Article in press: January 14, 2017
Peer-review started: September 5, 2016
P- Reviewer: Contreras CM, Serafini G S- Editor: Song XX L- Editor: A E- Editor: Wu HL
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World J PsychiatryWJPWorld Journal of Psychiatry2220-3206Baishideng Publishing Group Inc jWJP.v7.i1.pg3410.5498/wjp.v7.i1.34Systematic ReviewsNeuroimaging studies of cognitive remediation in schizophrenia: A systematic and critical review Penadés Rafael González-Rodríguez Alexandre Catalán Rosa Segura Bàrbara Bernardo Miquel Junqué Carme Rafael Penadés, Alexandre González-Rodríguez, Rosa Catalán, Miquel Bernardo, Department of Psychiatry and Psychology, Clinical Institute of Neurosciences, Hospital Clínic, 08036 Barcelona, SpainBàrbara Segura, Carme Junqué, Neuropsychology Lab, University of Barcelona, 08036 Barcelona, SpainBàrbara Segura, Carme Junqué, Institut d’Investigacions, Biomèdiques August Pi i Sunyer, 08036 Barcelona, SpainAuthor contributions: Penadés R designed the research; Gónzalez-Rodríguez A performed the bibliographic search; Penadés R, Segura B and Junqué C analysed the data; Penadés R wrote the paper; Catalán R, Bernardo M and Junqué C supervised the paper; all of the authors read and approved the final manuscript.
Correspondence to: Rafael Penadés, PhD, Department of Psychiatry and Psychology, Clinical Institute of Neurosciences, Hospital Clínic, C/ Villarroel 170, 08036 Barcelona, Spain. rpenades@clinic.ub.es
Telephone: +34-93-2275400 Fax: +34-93-4035294
22 3 2017 22 3 2017 7 1 34 43 30 8 2016 14 10 2016 13 12 2016 ©The Author(s) 2016. Published by Baishideng Publishing Group Inc. All rights reserved.2016Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/AIM
To examine the effects of cognitive remediation therapies on brain functioning through neuroimaging procedures in patients with schizophrenia.
METHODS
A systematic, computerised literature search was conducted in the PubMed/Medline and PsychInfo databases. The search was performed through February 2016 without any restrictions on language or publication date. The search was performed using the following search terms: [(“cogniti*” and “remediation” or “training” or “enhancement”) and (“fMRI” or “MRI” or “PET” or “SPECT”) and (schizophrenia or schiz*)]. The search was accompanied by a manual online search and a review of the references from each of the papers selected, and those papers fulfilling our inclusion criteria were also included.
RESULTS
A total of 101 studies were found, but only 18 of them fulfilled the inclusion criteria. These studies indicated that cognitive remediation improves brain activation in neuroimaging studies. The most commonly reported changes were those that involved the prefrontal and thalamic regions. Those findings are in agreement with the hypofrontality hypothesis, which proposes that frontal hypoactivation is the underlying mechanism of cognitive impairments in schizophrenia. Nonetheless, great heterogeneity among the studies was found. They presented different hypotheses, different results and different findings. The results of more recent studies interpreted cognitive recovery within broader frameworks, namely, as amelioration of the efficiency of different networks. Furthermore, advances in neuroimaging methodologies, such as the use of whole-brain analysis, tractography, graph analysis, and other sophisticated methodologies of data processing, might be conditioning the interpretation of results and generating new theoretical frameworks. Additionally, structural changes were described in both the grey and white matter, suggesting a neuroprotective effect of cognitive remediation. Cognitive, functional and structural improvements tended to be positively correlated.
CONCLUSION
Neuroimaging studies of cognitive remediation in patients with schizophrenia suggest a positive effect on brain functioning in terms of the functional reorganisation of neural networks.
Cognitive remediationCognitive trainingNeuroimagingCognitionPrefrontal cortexThalamusPlasticitySchizophrenia
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Core tip: Cognitive remediation therapy for schizophrenia is an evidence-based psychological treatment that aims to improve cognitive dysfunction. However, its underlying neural mechanisms have not been established. Several neuroimaging studies have shown positive effects in terms of brain activation. However, the results have been heterogeneous and difficult to integrate. The primary aim of the present review was to analyse systematically all of the published trials that used neuroimaging procedures. Additionally, we performed a more qualitative analysis examining the possible influence of neuroimaging methods and the use of different theoretical frameworks.
INTRODUCTION
Cognitive remediation therapy for schizophrenia is a psychological treatment that proposes to ameliorate cognitive dysfunction. It has been defined as a behavioural training-based intervention that aims to improve cognitive processes (attention, memory, executive function, social cognition or metacognition) with the goal of durability and generalisation[1]. Although the described effects have been modest, several trials and two meta-analyses have established its efficacy, improving not only cognition but also daily functioning[1,2]. Nonetheless, the underlying neural mechanisms of this treatment have not yet been well established.
Over the past few years, several neuroimaging studies have been conducted with the intention of identifying the different brain mechanisms underlying cognitive recovery. Some positive effects in terms of brain activation have been described, although the results have been heterogeneous[3,4]. Owing to this heterogeneity among the studies presenting different hypotheses, different results and different findings, we understand the need to review systematically all of the published works to provide new insights that would help to generate a new hypothesis in the near future. Moreover, recent revisions in the field of neuroimaging have indicated the need to explore not only the results but also the methods and theoretical frameworks[5].
The objective of the present review was to analyse neuroimaging studies that have tested the effects of cognitive remediation on brain functioning in patients with schizophrenia. To do so, we systematically reviewed published trials that used a cognitive remediation treatment and neuroimaging procedures. Additionally, we performed a more qualitative analysis examining the possible influence of neuroimaging methods and the use of different theoretical frameworks.
MATERIALS AND METHODS
Literature search
A systematic, computerised literature search was conducted in different online scientific databases: PubMed/Medline and PsychInfo. The search was performed through February 2016 without any restrictions on language or publication date. The search was performed using the following search terms: [(“cogniti*” and “remediation” or “training” or “enhancement”) and (“fMRI” or “MRI” or “PET” or “SPECT”) and (schizophrenia or schiz*)]. This search was accompanied by a manual online search and review of the references from each of the papers selected, and those papers fulfilling our inclusion criteria were also included.
The following inclusion criteria were applied. Studies in which any imaging technique was used to assess the effect of cognitive training were selected. Assessments had to be conducted both at baseline and also after therapy. We excluded those articles that did not report any results, for instance, presentations or descriptions of interventions or study designs. Regarding the intervention, we only included studies in which patients were provided with multiple sessions of cognitive training, and programmes focusing only on social cognition were excluded.
RESULTS
In total 101, studies were obtained, and 18 of them fulfilled the inclusion criteria (Figure 1). In addition to the differences in neuroimaging variables that will be analysed in subsequent paragraphs, an important heterogeneity in the characteristics of the retrieved studies was found (Table 1). Cognitive intervention approaches frequently differed among the studies, ranging from paper and pencil tasks, computerised cognitive training, training delivered in group format or individualised sessions with a therapist, simple auditory training, multimodal training and so on. The duration of the therapies ranged from less than one week to two complete years, with the mean duration of the training being 12.47 wk and 11 studies (64.7%) being between 10 and 16 wk in length. In addition, the cognitive remediation approaches focused on a single cognitive function to others focusing on all cognitive aspects possible, including social cognition. Because of the heterogeneity of the methodologies, interventions and assessments, we decided to rely on a qualitative description rather than a quantitative analysis.
Table 1 Studies included in the systematic review
Ref. Participants Treatment Treatment duration (wk) Imaging method Experimental task Neural treatment effects Direction of change
Cognitive remediation
Wykes et al[8] SCH = 2 CRT 12 SPECT Verbal fluency Bilateral frontal, temporal, parietal and occipital ↑
Penadés et al[9] SCH = 2 CRT 12 SPECT Tower of London Prefrontal activity ↑
Wexler et al[11] SCH = 8 CRT 10 fMRI Auditory verbal memory L inferior frontal ↑
Penadés et al[10] SCH = 8 CRT 12 SPECT Tower of London Prefrontal activity ↑
Wykes et al[12] SCH = 12 HC =6 CRT OC HC 12 fMRI N-back R inferior frontal gyrus and bilateral occipital activity ↑
Eack et al[20] SCH = 53 CET EST 52 MRI - Loss of GM in temporal cortex, including the L parahippocampal gyrus, L amygdala, bilateral anterior cingulate, and L hippocampus ↓
GM in L amygdala ↑
Haut et al[13] SCH = 21 HC = 9 CRT CBSST 6 fMRI N-back, lexical task L prefrontal activity Case report series
Rowland et al[15] SCH = 17 HC = 17 CRT < 1 fMRI, VBM L amygdala, bilateral inferior parietal regions ↑
Controls also exhibited activation reductions in region and spatial extent with relational learning proficiency ↓
Edwards et al[14] SCH = 22 HC = 14 CRT 22 fMRI Continuous performance task R middle frontal R superior parietal cortex R inferior frontal junction R visual cortex Cerebellum ↑↓
Bor et al[16] SCH = 20 HC = 15 CRT 8 fMRI N-back L inferior/middle frontal gyrus, cingulate gyrus and inferior parietal lobule activity ↑
Subramaniam et al[19] SCH = 31 HC = 16 AT 13 fMRI Word generation and recognition Medial PFC activity ↑
Penadés et al[21] SCH = 31 HC = 16 CRT SST 15 fMRI, DTI N-back L superior parietal lobule and bilateral middle frontal gyri activity ↑
DMN activity in L precuneus and middle frontal gyrus ↓
FA in CC and R posterior thalamic radiations ↑
Vianin et al[22] SCH = 16 CRT 8 fMRI Verbal fluency Inferior parietal lobule, precentral gyrus, Broca’s area, middle occipital cortex, middle cingulate cortex, and superior parietal lobule activity ↑
Subramaniam et al[23] HC = 15 SCH = 30 AT 15 fMRI N-back Middle frontal and inferior frontal gyri activity ↑
Social-cognitive remediation
Haut et al[13] SCH = 20 HC = 10 TAR TAU 10 fMRI Facial affect recognition L middle and superior occipital lobe, R inferior and superior parietal cortex, and L and R inferior frontal cortex activity ↑
Combination of cognitive and social-cognitive remediation
Hooker et al[17] SCH = 22 AT + SCT 11 fMRI Facial emotion recognition Postcentral gyrus activity ↑
Hooker et al[18] SCH = 22 AT + SCT 11 fMRI Facial emotion recognition L and R amygdala, R putamen and R medial prefrontal cortex ↑
SPECT: Single photon emission computed tomography; fMRI: Functional magnetic resonance imaging; GM: Grey matter; DMN: Default mode network; FA: Fractional anisotropy; CC: Corpus callosum; AT: Auditory-based cognitive training; SCT: Social cognitive training; SCH: Schizophrenia; HC: Healthy control.
Figure 1 Diagram of literature search.
First period: Improving brain activation
The first studies performed in the 1990s seemed to be inspired by the simple assumption that cognitive remediation would be able to cause some detectable effects on brain functioning. Thus, any visible changes in brain functioning would be considered a success. During that period, the use of functional neuroimaging techniques, such as positron emission tomography (PET) and single photon emission computed tomography (SPECT) procedures, were predominant. Both procedures helped to establish the hypothesis of hypofrontality. Hypofrontality was defined as a state of decreased cerebral blood flow or reduced utilisation of glucose in the prefrontal cortex of the brain[6,7]. Thus, testing cognitive remediation with PET or SPECT was the best option for researchers, more specifically in the context of the hypothesis of hypofrontality using analysis of regions of interest (ROIs), in this case, the prefrontal cortex. Thus, any detectable change in terms of brain activation indicating any sort of reduction of the hypofrontality would be proof that cognitive remediation was working well.
Thus, the first study to test the effects of cognitive remediation through SPECT procedures was performed by Wykes et al[8], who reported that two patients showed changes in frontal perfusion patterns after cognitive treatment. Penadés et al[9] found similar results, describing an increase in prefrontal blood flow during task performance following cognitive treatment in a case report study including two patients. These results were extended and confirmed in a later study with a small sample of eight patients[10]. However, two intriguing aspects from these studies raised questions that remain open. Firstly, not only increases but also decreases in the activation of some specific brain regions could be related to cognitive improvement. In the Wykes et al[8], not only increased but also decreased activity was found in the bilateral frontal, temporal, parietal and occipital regions. Secondly, another open question is the variables that could explain the intersubject variability, preventing the success of cognitive remediation in some patients. In a study by Penadés et al[9] with two patients, one had clearly improved prefrontal brain activation, while no significant changes were found in the other patient. Nonetheless, despite these and other possible open questions, this initial period offered promising results that were able to establish the idea that cognitive remediation is able to improve brain activation and eventually reduce hypofrontality. This line of thought was applied by Wexler et al[11] using a different methodology: Functional magnetic resonance imaging (fMRI). They described in a longitudinal study the progressive effects of cognitive remediation on brain functioning. In particular, they found increased task-related activation in the prefrontal cortex, which is the same brain region that was activated during memory tasks in healthy individuals. Improvement in brain activation was associated with cognitive changes, specifically verbal memory improvement.
In summary, in this initial period from 1998 to 2002, both SPECT and fMRI studies were able to detect changes in brain functioning after cognitive remediation. Data analyses were mainly based on particular regions of interest that were defined a priori and were mainly located in regions of the prefrontal cortex. Unfortunately, these studies had small samples and lacked control groups to exclude placebo effects. Nonetheless, during this period, no other treatment was able to show any changes in brain functioning related to cognitive improvement in schizophrenia.
Second period: Testing the hypofrontality hypothesis
Wykes et al[12] conducted a controlled study in which 12 patients were randomly assigned to control therapy or cognitive remediation. The effects of the intervention were tested with fMRI procedures using the n-back task during the scanning. The intervention was delivered on an individual basis and involved a therapist and paper and pencil tasks. Not surprisingly, only the group receiving cognitive remediation showed a significant increase in the activation of brain regions associated with working memory, particularly the inferior frontal gyrus. Although the sample size was still small, this study confirmed the insights from the previous period using a convincing methodology. It could be said that it was the first time that brain activation changes were clearly associated with the cognitive remediation intervention by applying a reliable and rigorous methodology. In conclusion, cognitive remediation acted as an active treatment to improve cognition, and it was also able to improve brain functioning in prefrontal regions in patients with schizophrenia. Thus, the need to replicate these results appeared to be the main target of successive studies.
Subsequent posterior studies showed similar results. Haut et al[13] conducted a quasi-randomised study involving nine patients receiving cognitive remediation, nine patients receiving a control therapy in the form of social skills training, and nine healthy control subjects. The authors showed that patients receiving cognitive remediation presented some increases in the activity of the left dorsolateral prefrontal cortex, left dorsal prefrontal cortex, anterior cingulate, right and left prefrontal cortex. The authors used fMRI procedures and visual n-back tasks containing words or pictures, as well as a lexical decision task. Patients receiving cognitive remediation improved on the word and picture 2-back tasks, showing more improvement than the control treatment group. Unfortunately, only regions of interest were examined. Edwards et al[14] used event-related fMRI to analyse brain activity associated with cognitive remediation. The sample comprised 22 patients with schizophrenia and a matched control group of 14 healthy participants. The training protocol emphasised direct encoding of contextual cues and updating of response selection goals in accordance with cue information. Following training, increased activation was observed in several areas involving anterior and posterior brain regions, such as right middle frontal, right superior parietal cortex, right inferior frontal junction, and left inferior frontal and visual cortex. These effects on brain activation seemed to be related to both clinical and cognitive improvements. Unfortunately, the analyses were also based on previously defined regions of interest.
Rowland et al[15] conducted an interesting study investigating the effects of cognitive training in the context of a relational learning task and using fMRI procedures. The sample comprised 17 patients with schizophrenia and 17 healthy control subjects. The most important innovations of this study were the use of whole-brain analysis and the fact that the healthy controls were also tested after having undergone cognitive training. Firstly, the authors found different patterns in both groups before and after treatment. The controls engaged regions including the frontal, parietal, and medial temporal lobes. After the training, the controls showed activation reductions in these regions and spatial extent in areas related to learning improvement. These findings are commonly observed phenomena in successful learning, but they were new in the context of cognitive training. Conversely, thee subjects with schizophrenia displayed bilateral inferior parietal region activation, as the authors had predicted.
Bor et al[16] conducted a study that explored the impact of cognitive remediation in a sample of 17 patients and 15 healthy volunteers. Throughout the study, all of the patients were on stable doses of atypical antipsychotics. The authors used fMRI and a visual 2-back test after 28 h of computerised cognitive remediation, comparing baseline with after treatment measurements in a randomised, controlled trial. Following treatment, patients in the group that received cognitive remediation exhibited higher levels of activation for the left inferior-middle frontal gyrus, cingulate gyrus, and inferior parietal cortex. These changes were related to improvement in measures of strategic efficiency and sustained attention. Hooker et al[17,18], in two studies with the same sample, tested the effects of a cognitive remediation programme plus a social cognitive intervention together in a sample of 22 schizophrenia patients. The authors used an fMRI task of positive and negative facial emotion recognition, showing improvements in postcentral gyrus activity, the left and right amygdala, the right putamen and the right medial prefrontal cortex. The particular choice of the fMRI task and the use of a combined treatment made it difficult to interpret whether these effects on brain functioning were the results of the cognitive treatment or the social cognitive treatment or even of the combination of both treatments.
Finally, Subramaniam et al[19] performed a controlled study with 31 schizophrenia patients and 16 healthy controls, but randomisation was not performed Almost all of the patients were taking atypical antipsychotics throughout the study. During fMRI scanning, tasks of word generation and recognition of words were used. Computerised cognitive training was used to examine its effects on regions related to reality monitoring. The authors found that patients exhibited less activation in the medial prefrontal cortex during word recognition for words at baseline. After cognitive remediation, the patients somewhat normalised their activation patterns, although they still had less activity than healthy controls. One important thing to note in this study was the use of a more complex theoretical framework of brain activation. However, owing to the use of the region of interest approach by the authors, the study precluded the detection of other possibly relevant changes in activity.
In summary, in this second period from 2002 to 2011, different studies consolidated that cognitive remediation acts by improving brain activation in the prefrontal lobes and other related regions. The use of fMRI totally replaced the use of other methods, such as SPECT or PET. Data analyses were still based mainly on predefined regions of interest, but whole-brain analysis opened a new pathway. The methodology was heterogeneous across the different studies, but some of them began to attain the highest standards. Moreover, hypofrontality is the current framework, and an increase of activity is always considered a success criterion. However, some studies have suggested going beyond the hypofrontality hypothesis because cognitive remediation may have some detectable effects in other brain areas. In addition, more brain activation does not necessarily indicate better brain functioning. At least in healthy people, a decrease in activation in some brain areas could be correlated with better cognitive performance.
Neuroprotection: Changes in brain morphology
Eack et al[20] conducted a study that was unique in many aspects, and it is probably one of the most influential works published in the field. The aim of the study was basically to test the option to detect changes in brain morphology after treatment by cognitive rehabilitation. A randomised, controlled trial was performed with a longitudinal design for 2 years, with annual assessments of cognition and structural MRI. Statistical analyses were based on a mixed effects model, while processing of the neuroimaging data was based on voxel-based morphometry methods. Volumetric analyses of regions of interest in different areas of the frontal and temporal regions were performed a posteriori. A sample of 53 patients with diagnoses of schizophrenia or schizoaffective disorder in the early course was included. They were symptomatically stable and, consequently, their doses of antipsychotics were also stable. Cognitive remediation was an integrated approach that combined cognitive computer training and group-based social cognitive exercises. A control group followed an active control based on supportive therapy to improve illness management. It provided psychoeducation and coping strategies training.
Astoundingly, patients who received cognitive remediation showed greater preservation of grey matter volume over 2 years. A main effect of time indicated loss of grey matter in some brain areas, such as the bilateral cerebellum, left medial and posterior cingulate. Additionally, an interactive effect of time and treatment suggested that patients showed less grey matter loss in the left parahippocampal and fusiform gyrus and even greater grey matter increases in the left amygdala following cognitive remediation. Interestingly, these changes were statistically related to cognition changes. The authors appealed to the possible neurobiologic protective effects of cognitive remediation, particularly in early schizophrenia. Unfortunately, this work has not yet been replicated.
Third period: Going beyond hypofrontality and testing connectivity changes
Penadés et al[21] conducted a trial using a whole-brain approach that combined fMRI and diffusion tensor imaging (DTI). They investigated the effect of cognitive remediation on brain functioning in a randomised, controlled trial with 30 schizophrenia outpatients with an experimental group and an active control group. Additionally, 15 healthy volunteers were also included as a second comparison group. Cognitive remediation consisted of an individual strategy-learning-based treatment implemented by a trained therapist, based on paper and pencil exercises. The control group used an active control with an identical duration based on an individual social skills training that provided information about illness management. Brain activation patterns were assessed during an n-back task using independent component analysis as implemented in multivariate exploratory linear decomposition into independent components. This analysis showed clear differences between schizophrenia patients and healthy participants. Despite having performed similarly on the n-back task, patients with schizophrenia showed two different networks that were overactive compared to the healthy participants: The central executive network and default mode network. After treatment, the activation pattern significantly changed only in the cognitive remediation group in the sense of normalising towards the patterns observed in healthy controls Thus, decreased activation was found in the left superior parietal lobule and bilateral middle frontal gyri. In addition, decreased activity in the default-mode network was found in the left precuneus and middle frontal gyrus, among other areas, allowing for activation of the central executive network and deactivating of the default mode network in a more proper manner, suggesting an improvement in the efficiency of both networks. Furthermore, analysis of white matter on DTI showed an increase in the fractional anisotropy index in the anterior part of the genu of the corpus callosum. Interestingly, after treatment, statistically significant correlations were found among cognitive, functional, and structural changes. Finally, the authors speculated that cognitive improvement could be based on an increase of interhemispheric information transfer between the bilateral prefrontal cortices via the corpus callosum.
Another interesting and innovative result was reported by Vianin et al[22]. The authors performed a single-blind, randomised trial with sixteen patients distributed into an experimental group of cognitive remediation and a treatment-as-usual control group. Cognitive remediation was based on executive function training lasting 14 wk. The authors tested brain activation patterns using a covert verbal fluency task during fMRI. In addition to cognitive improvements, the authors reported increased activation in many areas, such as the inferior parietal lobule, precentral gyrus, inferior frontal gyrus (Broca’s area), middle occipital cortex, middle cingulate cortex, and superior parietal lobule, in the cognitive remediation group compared to the control group after treatment. Particularly interesting was the increased activation in Broca’s area. The authors hypothesised that the use of metacognitive techniques of verbalisation might be the main factor underlying these brain changes.
Finally, Subramaniam et al[23] used n-back tasks in an fMRI study comparing computerised auditory and sociocognitive training based on a video game with an active control group and a group of healthy controls. They observed baseline hypoactivation in the middle frontal gyrus at baseline for the patient group. After treatment, the sociocognitive group showed a greater increase in activity in the middle frontal and inferior frontal gyri. One striking and interesting finding in this study was the correlation between the increase in right frontal activation on the verbal n-back task and the increase in the activation in left frontal regions. These results could suggest a process of increased connectivity after cognitive treatment.
Summarising the period since 2013 until today, the studies have definitively gone beyond the hypothesis of hypofrontality. A new and wider theoretical framework is emerging, and it includes more recent discoveries, such as the connectivity between different brain networks (Figure 2). Now, the focus is not only on task-related performance but also on rest-related brain functioning, which involves different interconnected regions that should be highly active at rest but that should be deactivated during the performance of cognitive tasks, such as the default mode network. For this reason, improvement can no longer be expressed only in terms of simple activation increases. Another feature of this period is the focus on other nonspecific prefrontal cortex areas such as the ventral regions or Broca’s area, which could be related to some aspects of the remediation process. These findings are changing the focus of neuroimaging studies and are possibly providing a more complex and accurate picture of the brain mechanisms underlying the effects of cognitive remediation.
Figure 2 Evolution of neuroimaging studies, data analysis and theoretical frameworks. PEG: Pneumoencephalagraphy; CAT: Computed axial tomography; SPECT: Single-photon emission tomography; PET: Positron emission tomography; MRI: Magnetic resonance imaging; fMRI: Functional magnetic resonance imaging; MEG: Magneto encephalography; DMN: Default mode network.
Meta-analyses
Two meta-analyses have been performed. Ramsay et al[24] conducted an Activation Likelihood Estimation (ALE) meta-analysis. After a literature search, they identified 162 articles, but only 9 of them were included in the analysis. ALE analyses showed increased activity in several brain areas, such as the lateral and medial prefrontal cortex, parietal cortex, insula, and the caudate and thalamus. Wei et al[25], with the same number of studies, found similar but not identical results: Increased brain activation occurred in thee frontal and parietal lobes, including the left medial frontal gyrus, left inferior frontal gyrus, right middle frontal gyrus, right postcentral gyrus, and inferior parietal lobule. The main results of the meta-analyses confirmed the insights of previous studies. However, secondary analyses could add even more information to the state of art. For instance, an original secondary analysis in the Ramsay et al[24] study was performed to compare the brain areas involved in cognitive remediation with areas that had been previously associated with deficits in working memory and executive control in persons with schizophrenia. Surprisingly, they found that some areas, such as the left prefrontal cortex and thalamus, overlapped, but other areas did not, suggesting both restorative and compensatory mechanisms. Another interesting secondary analysis showed that cognitive remediation resulted in similar patterns of brain activation irrespective of the different treatment approaches.
Nonetheless, the results from these two meta-analytic studies should be interpreted with great caution. The number of the included studies (n = 9) was extraordinarily small. In addition, there was a risk of bias due to the heterogeneity among these nine studies. Beyond differences in remediation approach and neuroimaging methods, the studies used different types of control groups and different methods of randomisation, and also blinding was absent in some studies but not in others. Statistical analysis was performed using different methods, making the results difficult to compare because some studies used mixed models and others used a general lineal model; some used data substitution, and others did not; some used the intention-to-treat procedure, and others did not. In terms of neuroimaging processing, different software was used; some studies reported results in terms of interaction effects between time and treatment and others in terms of differences between baseline and posttreatment, and while some studies used whole-brain analysis, others were based on analysis of ROIs. Although Wei et al[25] found similar increased activation brain areas in analysis with or without ROI studies, they found that analysis including ROI studies yielded a higher ALE value. Future studies with larger numbers of studies and more homogenised methodologies will provide us with more consistent results.
DISCUSSION
Cognitive remediation seems to improve brain activation when it is tested by means of neuroimaging techniques. Changes involving the prefrontal and thalamic regions were the most commonly reported results in the reviewed studies as in other previous systematic reviews[3,4,26]. These findings were in agreement with the hypofrontality hypothesis, proposing frontal hypoactivation as the underlying mechanism of cognitive impairments in schizophrenia. Nonetheless, advances in neuroimaging methodology, such as the use of whole-brain analysis, tractography, graph analysis, and other sophisticated methodologies of data processing, might have conditioned the interpretation of results, generating new theoretical frameworks.
In fact, more complex theoretical frameworks are currently reinterpreting hypofrontality. Current theories are focusing on other aspects, such as the connectivity between different brain networks. In addition, not only task-related but also rest-related brain functioning is being considered. Consequently, different interconnected regions should be active at rest, but they should be deactivated during cognitive tasks. Improvement can no longer be expressed exclusively in terms of activation increases. Thus, the results of more recent studies are interpreting cognitive recovery within this framework, showing improvement in the efficiency of different networks. Additionally, structural changes have been described in both the grey and white matter suggesting a neuroprotective effect of cognitive remediation. Cognitive, functional and structural improvements have tended to appear positively correlated.
Results from meta-analytic studies have confirmed the active role of cognitive remediation in brain function involving the prefrontal and thalamic areas. However, other brain changes after treatment have been described. Consequently, cognitive recovery seems to be mediated by restoration and compensation mechanisms at the same time. Moreover, neuroimaging findings are not linked to a particular remediation approach, and all of the different cognitive remediation approaches act similarly in terms of brain functioning. Despite these findings, some limitations must be considered. Firstly, the evidence is tremendously incomplete because of the small number of studies and the lack of replicative studies. Secondly, different remediation approaches and different neuroimaging methods have made the comparison and generalisation of results problematic undertakings. Finally, the lack of a validated theoretical framework for the underlying neurobiological mechanisms of cognitive recovery has rendered the data difficult to interpret.
In conclusion, neuroimaging studies of cognitive remediation in patients with schizophrenia seem to have a positive effect on brain functioning in terms of the functional reorganisation of neural networks. Currently, the most commonly reported changes involve the prefrontal and thalamic regions. Structural changes in the grey and white matter have been described, suggesting a neuroprotective effect of cognitive remediation. Cognitive, functional and structural improvements appear to be positively correlated. Further randomised, controlled studies are needed to confirm and clarify these results, possibly in the context of more complex theoretical models, including different brain networks, aspects of connectivity, whole-brain analysis and multimodal neuroimaging.
COMMENTS
Background
Neuroimaging studies have been conducted by many authors with the intention of identifying the different brain mechanisms underlying cognitive recovery. Even though some positive effects in terms of brain activation have been described, results have been heterogeneous and difficult to integrate. Some studies have described increased brain activation and others have shown decreased activation patterns. The primary aim of this review was to examine systematically all the published trials using neuroimaging procedures. Furthermore, the analysis was intended following a qualitative analysis in order to investigate the influence of neuroimaging methodology and the use of different theoretical frameworks.
Research frontiers
Nowadays, a comprehensive theoretical framework for cognitive recovery is needed. In order to integrate all the studies that have already been published and to guide future research we need to reflect on how the hypothesis and results are evolving and how neuroimaging methodology has conditioned the results of the studies.
Innovations and breakthroughs
Nearly all the recruited neuroimaging studies testing cognitive remediation in patients with schizophrenia have been based on the hypothesis of hypofrontality. In addition, they were always performed using a task-related paradigm and using the “region of interest” methodology. Nowadays, the use of different methodologies such as the brain networks framework and the whole brain analysis has brought to light some new insights reconceptualising the previous findings. Thus, improving frontal activation is now understood in a broader framework that points to an improvement of the networks efficiency.
Applications
Beyond the necessary replicative studies, future research needs to explore different hypothesis such as the putative changes in connectivity patterns of the different brain networks.
Terminology
The efficiency of a network is described in network science as a measure of how efficiently it exchanges information. Brain networks are efficient when they are able to show enough but not excessive activation during cognitive and resting states.
Peer-review
In this systematic review, the authors have presented a qualitative and critical analysis of the neuroimaging studies paying close attention to the theory of the brain networks connectivity.
Supported by a grant from the Instituto de Salud Carlos III of Fondo de Investigaciones Sanitarias FIS, No. PI 11/09158 (to Penadés R).
Conflict-of-interest statement: All the authors declare that they have no competing interests for this article.
Manuscript source: Invited manuscript
Specialty type: Psychiatry
Country of origin: Spain
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Peer-review started: September 2, 2016
First decision: September 29, 2016
Article in press: December 14, 2016
P- Reviewer: Fakra E, Kapelski P, Müller MJ S- Editor: Qiu S L- Editor: A E- Editor: Wu HL
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World J PsychiatryWJPWorld Journal of Psychiatry2220-3206Baishideng Publishing Group Inc jWJP.v7.i1.pg4410.5498/wjp.v7.i1.44Systematic ReviewsAttention-deficit/hyperactivity disorder and suicide: A systematic review Balazs Judit Kereszteny Agnes Judit Balazs, Vadaskert Child and Adolescent Psychiatry Hospital, H-1021 Budapest, HungaryJudit Balazs, Agnes Kereszteny, Institute of Psychology, Eötvös Loránd University, H-1064 Budapest, HungaryAgnes Kereszteny, School of Ph.D. Studies, Semmelweis University, H-1086 Budapest, HungaryAuthor contributions: All authors contributed to this paper.
Correspondence to: Judit Balazs, MD, PhD, Institute of Psychology, Eötvös Loránd University, Izabella u. 46, H-1064 Budapest, Hungary. balazs.judit@ppk.elte.hu
Telephone: +36-1-3921400 Fax: +36-1-3921401
22 3 2017 22 3 2017 7 1 44 59 31 10 2016 2 1 2017 16 1 2017 ©The Author(s) 2016. Published by Baishideng Publishing Group Inc. All rights reserved.2016Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/AIM
To investigate suicidality and attention-deficit/hyperactivity disorder (ADHD), this paper aims to systematically review the literature as an extension of previous reviews.
METHODS
We searched five databases (Ovid MEDLINE, Psychinfo, PubMed, Scopus, Web of Science) with two categories of search terms: (1) suicide; suicidal; suicide behavior; suicide attempt; suicidal thought; and (2) ADHD.
RESULTS
The search resulted 26 articles. There is a positive association between ADHD and suicidality in both sexes and in all age groups. Comorbid disorders mediate between suicidality and ADHD.
CONCLUSION
Recognizing ADHD, comorbid conditions and suicidality is important in prevention.
Attention-deficit/hyperactivity disorderSuicideSystematic review
==== Body
Core tip: This review of the last four years strengthens previous findings that there is a positive association between attention-deficit/hyperactivity disorder (ADHD) and suicidality in both sexes and in all age groups. Suicidality should screen in patients with ADHD. Comorbid disorders mediate between suicidality and ADHD. Recognizing ADHD and comorbid conditions can be important in suicide prevention as well.
INTRODUCTION
Suicide prevention is a public health issue all over the world[1]. Recently, several studies have focused on attention-deficit hyperactivity disorder (ADHD) as a possible psychiatric disorder that may serve as a suicide risk factor as well[2-5]. One of the theoretical backgrounds of it is the construct of impulsivity, which is a well-know personality trait. Impulsivity is a core symptom of ADHD[6,7], moreover it is known, that it correlates to suicidal behavior[8]. Another theoretical background behind the possible association between ADHD and suicide is, that two-thirds of ADHD cases have at least one comorbid psychiatric diagnosis, which most often is conduct disorder, substance use or major depressive episode[9-11]. These comorbid disorders are well-known risk factors of suicide[12-15]. As ADHD is one of the most prevalent (2%-12%) psychiatric disorders among children and adolescents and in 40%-60% of the cases, it continues into adulthood[16,17], all additional knowledge on the possible association between ADHD and suicidality has high clinical importance and can add to suicide prevention.
The growing body of publications on ADHD and suicidality has already resulted in five review or summary papers on this topic. First, James et al[18] searched two electronic databases (MEDLINE, Psychlit) for the period from 1966 to 2003. In their review, they included psychological autopsy studies of teenage and young adult suicides and long-term follow-up studies of ADHD children. They found a positive association between ADHD and completed suicides in males, concluding that ADHD could increase the risk for suicide through comorbid conditions such as conduct disorder and depression. Second, Impey et al[19] performed a search for the period up to January 2011 using three main databases (MEDLINE, EMBASE and PSYCHINFO). They concluded from their review that most suicidal study groups showed a higher rate of ADHD than the controls: At least double the rate for suicidal ideation and around 1.5-2.0 times for suicide attempts and completion. The authors emphasized that comorbidity had a large influence, especially in the cases of delinquency and substance misuse. Third, Furczyk et al[20] published a selective review on the most important currently known associations between ADHD and suicidality. They concluded, similar to the previous reviews[18,19], that there is substantial evidence supporting an association between ADHD and increased suicide risk, and that it is at least partially mediated by comorbidities. They highlight the importance of raising the awareness of health professionals of the risk of suicide in ADHD patients, but further research on the long-term outcomes of the treatment of ADHD patients with a risk of suicide is needed. The selective review paper of Nigg[21] had a wider focus: He overviewed the current knowledge on the health-related impairments of ADHD, including smoking, drug abuse, accidental injury, sleep, obesity, hypertension and diabetes, as well as suicidal behavior. On the topic of ADHD and suicide, the author concluded that ADHD is associated with an elevated risk of suicide attempts (particularly in girls) and completed suicide (particularly in boys), and this risk is mediated by comorbid disorders, which may vary with gender: They include conduct and emotional problems in males and depression in females. Finally, we have to mention Renaud et al[22] summary paper: Based on some selected important research in the field, the authors concluded that there is not a direct link between ADHD and suicide, however, ADHD’s constructs of impulsivity and aggression are related to the development of conduct and oppositional defiant disorders, which can lead to deviancy and drug abuse; all of these comorbid conditions increase the risk of suicide.
Knowing of the growing interest in this topic over the last couple of years, we found it useful to conduct an up-to-date systematic review, which can provide important extensions. The search of James et al[18] was conducted more than one decade ago, and even Impey et al[19] completed their search in January, 2011. The most recently published reviews were not systematic[20-22]. Additionally, all of the reviews have mainly been limited to males[18,19]. Moreover knowing more about the methodology of the studies can lead to a better understanding of the prevalence data. Considering all of this, the current systematic review aims to present an overview on suicidality and ADHD as an extension of the previous ones, not only in the time period of the search, but also by focusing on the following topics: (1) Is ADHD more common in people who are suicidal? (2) Is suicide more prevalent in people with ADHD? and (3) Which other identifiable risk factors can be associated with suicide in ADHD?
Additionally, to be able to compare the included studies, we investigated what kinds of assessments are used for measuring ADHD, suicidality and comorbid conditions.
MATERIALS AND METHODS
Selection of publications
A systematic literature search was conducted in the following five computerized literature databases on January 27, 2015: Ovid MEDLINE, Psychinfo, PubMed, Scopus, Web of Science from 2011 to 2015. Search terms from two categories were used: (1) suicide; suicidal; suicide behavior; suicide attempt; suicidal thought; and (2) ADHD; attention deficit hyperactivity disorder. Search terms within both categories were separated by the Boolean operator OR, and the categories were separated by the operator AND. Using prespecified inclusion and exclusion criteria, we screened the titles and/or abstracts. The relevant full texts of papers that passed the first search were read, and the ones that met the inclusion criteria were collected. The reference lists of the retrieved papers were screened, and papers that possibly met the inclusion criteria were retrieved and studied. The inclusion criteria were: Peer-reviewed journals; publications written in English or Hungarian. The exclusion criterion was the lack of any empirical data. It was not in the focus of our study to examine suicidal behavior, as a safety concern about ADHD drug treatment. We excluded those studies, which aim was to examine pharmacological treatment (e.g., atomoxetine) induced suicide in patients with ADHD, e.g., Capuano et al[23], who present a series of cases of Italian children who experienced suicidal ideation during ADHD pharmacological therapy with atomoxetine.
RESULTS
Included studies
The search strategy resulted in a total of 278 articles (excluding duplicates), of which 26 were included in the systematic review after the screening process (Figure 1, Tables 1-3).
Table 1 Included relevant articles examining attention-deficit/hyperactivity disorder and suicidality from January 2011 to January 2015: Attention-deficit/hyperactivity disorder in suicidal patients
ADHD in suicidal patients
Ref. Country Study design Sample Population at onset Population’s age at onset Measures for ADHD, comorbid conditions and suicidality Main findings
Ben-Yehuda et al[24] Israel Cross-sectional Clinical sample The survey involved all minors (age < 18) (n = 266) who were referred to a psychiatric emergency department due to a suicide attempt or suicidal ideation during a 3-yr period (2005-2007) Children: Age range: ≤ 12 yr Adolescents: Age range: > 12 yr The diagnosis was made by the examiner in the emergency department: diagnoses were coded using the ICD-10 The distribution of psychiatric diagnoses differed significantly in the two age groups ADHD was significantly more prevalent among suicidal children, while mood disorders were more prevalent among suicidal adolescents The second most prevalent diagnosis among suicidal children was ADHD (25.6%) (following adjustment disorder/38.5%/and followed by conduct disorders/23.1%) In adolescents ADHD was not among the most common diagnoses: it was found in only 5.7% in the adolescent group
Evren et al[25] Turkey Cross-sectional Community sample A representative sample of 10th grade students: n = 4938 (male ratio: 52.7%) Mean age: 15.58 yr (SD = 2.85) PSTA Those with a lifetime suicidal thoughts had a higher mean ADHD symptom score than those without. Suicidal thoughts predicted the symptoms of ADHD
Soole et al[26] Australia Cross-sectional Community sample 469 deaths by external causes were recorded in the Queensland CDR for children and adolescents aged 10-17 between 2004 and 2012 Between 2004 and 2012, 149 suicides were recorded: 34 of children aged 10-14 yr and 115 of adolescents aged 15-17 yr Causes of death were categorized using the ICD-10 Mental and behavioral disorders were observed in 50% of children and 57.3% of adolescents who died by suicide. Disorders usually diagnosed in infancy, childhood, and adolescence, such as ADHD, were significantly more frequent in children than in adolescents. Mood disorders, such as depression, were significantly more common in adolescents compared with children
CDR: Child Death Register; ADHD: Attention-deficit/hyperactivity disorder; PSTA: Psychological screening test for adolescents.
Figure 1 QUORUM flow chart detailing results of literature search. ADHD: Attention-deficit/hyperactivity disorder.
Table 2 Included relevant articles examining attention-deficit/hyperactivity disorder and suicidality from January 2011 to January 2015: Suicidality in patiens with attention-deficit/hyperactivity disorder
Suicidality in patiens with ADHD
Ref. Country Study design Sample Population at onset Population’s age at onset Measures for ADHD, comorbid conditions and suicidality Main findings
Agosti et al[27] United States Cross-sectional Clinical sample Current ADHD: 365 adults: With Suicide attempts: n = 59 No suicide attempts: n = 306 Age range: 18-66 yr CIDI, ACDS, DIS-IV Sixteen percentage of participants with current ADHD diagnosis had previous suicide attempt. While ADHD increased the risk of previous suicide attempt only 1.5 fold, having one or more comorbid disorders increased the risk of previous suicide attempt 4 to 12 fold
Balazs et al[28] Hungary Cross-sectional Clinical sample ADHD and subthreshold ADHD children: n = 220 ADHD and subthreshold ADHD adolescents: n = 198 Children: Age range: 3-11 yr Mean age: 7.67 yr (SD = 2.03) Adolescents: Age range: 12-17 yr Mean age: 14.31 yr (SD = 1.67) MINI-KID The relationship between ADHD and suicidality was fully mediated by comorbid psychiatric disorders. In children, symptoms of anxiety disorders mediated this relationship, while in the adolescent group, symptoms of major depressive episode, dysthymia, and substance abuse/dependence were found to be significant mediators
Barbaresi et al[29] United States Cross-sectional Community sample Adults with childhood ADHD: n = 232 Non-ADHD controls: n = 335 ADHD group: Mean age: 27 yr Non-ADHD group: Mean age: 28.6 yr MINI The rate of death from suicide was significantly higher among adults with childhood ADHD compared to non-ADHD adults
Cheng et al[30] Taiwan Cross-sectional Community sample 5405 University students: n = 5405 (male ratio: 64.8%) ADHD symptoms were elevated in 8.6% of the sample: (male ratio: 75.1%) University students ASRS, BSRS-5 Individuals with higher levels of ADHD symptoms were more likely to have higher suicidal ideation
Huntley et al[31] United Kingdom Cross-sectional Clinical Sample Participants from two in-patient alcohol and drug detoxification units: n = 226 (male ratio: 76.5%) Patient with alcohol/drug intoxication + ADHD: n = 11 Patient with alcohol/drug intoxication without ADHD: n = 183 Mean age: 39.0 yr (SD = 10.3) DSM-IV 18-item self-report ADHD screening questionnaires for both current and childhood behavior Impairment questions from the Barkley scales DIVA Patients with both substance use disorders and ADHD had significantly higher rates of prior suicide attempts than patients with substance use disorder without ADHD
Hurtig et al[32] Finland Longitudinal: 16 yr. First follow up: at ages 7, 8, second follow up at ages 15, 16 Community sample ADHD adolescents: n = 104 Non-ADHD adolescents: n = 169 Adolescents from the same birth cohort At 8 yr of age: Rutter B2 During the 15-16 yr follow up: SWAN, K-SADS-PL Adolescents with ADHD had more suicide ideation, acts than adolescents without ADHD. The effect of ADHD on suicidal ideation remained strong after controlling for other variables
Kavakci et al[33] Turkey Cross-sectional Community sample 980 university students (male ratio: 55.9%) ADHD: n = 48 Non-ADHD: n = 932 Age range: 17-44 yr Mean age: 21.4 yr (SD = 2.3 yr) ASRS SCID I, SCID II, Adult ADHD Module of MINI Plus Adolescents with ADHD reported significantly more lifetime suicide attempts than those without ADHD
Keresztény et al[34] Hungary Cross-sectional Clinical sample Children: n = 168 (male ratio: 87.5%) Adolescents: n = 43 (male ratio: 62.8%) Children: Age range: 3-12 yr Mean age: 8.23 yr (SD = 2.22) Adolescents: Mean age: 14.65 yr (SD = 1.6 yr) boys: 27 (62.8%) MINI-KID The most common comorbid diagnoses with ADHD were oppositional defiant disorder, conduct disorder and suicide behavior in both age-groups. The rate of suicide behavior was 17% among children and 58% among adolescents
Ljung et al[35] Sweden Cross-sectional Patient and prescribed drug registers and population-based registers ADHD: n = 51707 (male ratio: 69.8%) Control: n = 258535 Age range: 3-40 yr Discharge diagnosis of ADHD Participants with ADHD had an increased risks of both attempted and completed suicide compared with control participants. This result was the same even after adjusting for comorbid psychiatric conditions. While the highest familial risk was reported among first-degree relatives, lower risk was observed among more genetically distant relatives. The results suggests that shared genetic factors are important for this association
Mayes et al[36] United States Cross-sectional Community and clinical sample 1706 children and adolescents with psychiatric disorders and typical development: ADHD-C: n = 566 (male ratio: 74.6%) ADHD-I: n = 235 (male ratio: 57.4%) Other psychiatric disorders (autism, depression/ anxiety, eating disorder, intellectual disability): n = 719 (male ratio: 67.2%) Typical: n = 186 (male ratio: 43.5%) Age range: 6-18 yr All participants had a clinical diagnosis of ADHD made by a licensed PhD psychologist. The clinical diagnosis was based on a comprehensive psychological evaluation including diagnostic inter- views with the parent and child, parent and teacher rating scales, review of educational and medical records, extensive psychological testing PBS All psychiatric groups had far more suicide behavior than typically developed children. ADHD-C: 20.7% had suicide ideation, 6.0% attempt ADHD-I: 7.3% had suicide ideation, 2.6% attempt
Mayes et al[37] United States Cross-sectional Clinical sample Children and adolescents with ADHD: n = 925 (male ratio: 68.5%) ADHD-C: n = 666 ADHD-I: n = 259 Age range: 3-16 yr Mean age: 8.8 yr (SD = 2.6) All participants had a clinical diagnosis of ADHD made by a licensed PhD psychologist. The clinical diagnosis was based on a comprehensive psychological evaluation including diagnostic inter- views with the parent and child, parent and teacher rating scales, review of educational and medical records, extensive psychological testing PBS - suicide ideation and attempt items For the total sample with ADHD, 15.8% had suicide ideation (sometimes or more) and 5.5% had attempts Ideation and attempts were more than twice as prevalent among participants with ADHD-C than among participants with ADHD-I ADHD-C: 19% had suicide ideation, 7% attempt ADHD-I: 7% had suicide ideation, 3% attempt Those, who had ADHD alone: 6% had suicide ideation and 2% had suicide attempt. Those, who had ADHD + co-occurring sadness and ODD, 46% had ideation and 21% had attempts
Park et al[38] South Korea Cross-sectional Community sample A total of 6081 subjects: Non-ADHD symptom group: n = 6012 ADHD symptom group: n = 69 Age range: 18-59 yr K-CIDI Adult ADHD Self-Report Scale Adult ADHD symptoms are significantly associated with lifetime suicidality. However, the association disappeared after adjusting for other comorbid psychiatric disorders
Swanson et al[39] United States Longitudinal: 10 yr: First 5 yr follow up and second 10 yr follow-up Community and clinical sample ADHD girls: n = 140 Non-ADHD girls: n = 88 Age range: 6-12 yr at ascertainment Mean age at 5 yr follow-up: 14.2 yr Mean age at 10 yr follow-up: 19.6 yr (range 17-24 yr) At ascertainment: DISC-IV First follow up: SNAP-IV, Second follow up: SIQ, Barkley Suicide Questionnair, DISC-IV-YA Women with a childhood diagnosis of ADHD-C, compared with those with ADHD-I and control group, were at higher risk for suicide attempts. Furthermore, women with a persistent ADHD diagnosis were at higher risk than women with a transient diagnosis and the control group
Van Eck et al[40] United States Cross-sectional Community sample Undergraduate psychology students: n = 627 (male ratio: 40%) Mean age: 20.23 yr (SD = 1.40) CSS BSI ADHD indirectly increased suicidal ideation through depression. The moderator factors in the indirect effect of ADHD on suicidal ideation were emotion regulation deficits of accepting negative emotions, emotional awareness, and goal-oriented behavior
ADHD: Attention-deficit/hyperactivity disorder; CIDI: Composite International Diagnostic Interview; ACDS: Adult ADHD Clinical Diagnostic Scale; DIS-IV: The Diagnostic Interview Schedule for DSM-IV; MINI-KID: Mini-International Neuropsychiatric Interview for children and adolescents; PBS: Pediatric Behavior Scale; MINI: Mini-International Neuropsychiatric Interview; ASRS: Adult Self-Report Scale; BSRS-5: Brief Symptoms Rating Scale; DIVA: Diagnostic Interview for ADHD in Adults; SWAN: Strengths and Weaknesses of ADHD symptoms and Normal Behaviors; SCID-I: Structured Clinical Interview for DSM-IV Axis I Disorders; ODD: Oppositional defiant disorder; K-CIDI: Korean version of Composite International Diagnostic Interview; SNAP-IV: Swanson, Nolan, and Pelham Rating Scale; SIQ: Self-Injury Questionnaire; DISC-IV-YA: Diagnostic Interview Schedule for Children 4th ed., Young Adult version; ADHD-C: ADHD combined type; ADHD-I: ADHD inattentive type, ADHD-HKS Questionnaire.
Table 3 Included relevant articles examining attention-deficit/hyperactivity disorder and suicidality from January 2011 to January 2015: Suicidality in patients with psychiatric disorders who have attention-deficit/hyperactivity disorder comorbidity
Suicidality in patients with psychiatric disorders who have ADHD comorbidity
Ref. Country Study design Sample Population at onset Population’s age at onset Measures for ADHD, comorbid conditions and suicidality Main findings
Bácskai et al[41] Hungary Cross-sectional Clinical sample 198 patients with drug dependence (male ratio: 76%) Drug dependent patients without ADHD: n = 154 Drug dependent patients with ADHD: n = 44 Age range: 18-40 yr Mean age of the whole sample: 27 yr (SD = 6.31) ASRS, EuroADAD, BDI Drug dependent patients with ADHD showed a significantly higher proportion of suicidal ideation, suicidal attempts and self-injuries associated with suicidal attempts than drug dependent patients without ADHD
Berkol et al[42] Turkey Cross-sectional Clinical sample Patients with BD type I and II Adult BP with ADHD: n = 23 Adult BP without ADHD: n = 32 BP adults with ADHD: Mean age: 35.1 yr (SD = 10.7) BP adults without ADHD: Mean age: 41.3 yr (SD = 13.0) ADHD scale Mood disorder modul of SCID-I-CV In the BP with ADHD group, the rate of suicide attempts (47.8%) was significantly higher than in the BP without ADHD group (21.9%)
Donev et al[43] Germany Cross-sectional Clinical sample Patients with schizophrenia according to ICD-10 criteria: n = 27 (14 male) Patients with schizophrenia and no ADHD: n = 15 Patients with schizophrenia and ADHD: n = 12 Age range: 18-44 yr Mean age: 25.7 yr (SD = 7.6) ADHD-HKS Questionnaire Among patients with both schizophrenia and ADHD there were significantly higher number of suicide attempts than among those with schizophrenia without ADHD
Huntley et al[31] United Kingdom Cross-sectional Clinical sample Participants from two in-patient alcohol and drug detoxification units: n = 226 (male ratio: 76.5%) Patient with alcohol/drug intoxication + ADHD: n = 11 Patient with alcohol/drug intoxication without ADHD: n = 183 Mean age: 39.0 yr (SD = 10.3) DSM-IV 18-item self-report ADHD screening questionnaires for both current and childhood behavior Impairment questions from the Barkley scales DIVA Patients with both substance use disorders and ADHD had significantly higher rates of prior suicide attempts than patients with substance use disorder without ADHD
Patros et al[44] United States Cross-sectional Community sample College students: n = 1056 (male ratio: 38.5%) Age range: 18 yr of age or older; 96.4% aged 18-24 yr CSS, HDSQ Higher hyperactive/attention symptoms were associated with increase in suicidal thoughts, suicide attempts, and need for medical attention after suicide attempts, among participants with depressed mood
Penney et al[45] Canada Cross-sectional Clinical sample Clients who presented for treatment at an addictions facility: n = 5990 (male ratio: 63.1%) Clients who reported being hospitalized for attempting suicide in the past year: n = 76 All other clients: n = 5914 Age range: 11-86 yr Mean age: 32.60 yr (SD = 14.55) Clients reported whether or not they had been diagnosed by a mental health professional in the last 12 mo and in heir lifetime Compared to all other clients, clients who attempted suicide in the past year were significantly more likely to have ADHD (9.2% vs 2.5%)
Sáez-Francàs et al[46] Spain Cross-sectional Clinical sample Adult CFS patients: n = 158 CFS patients with adult ADHD: n = 33 (male ratio: 3.0%) CFS patients without adult ADHD (male ratio: 6.4%) CFS + ADHD: Mean age: 47.55 yr (SD = 7.99) CFS: Mean age: 48.60 yr (SD = 8.88) CAADID Suicide risk was studied with the Plutchick Risk of Suicide Scale (Plutchik et al, 1989), a 15-item self-report scale with dichotomous responses. Values above the cut-off point of 6 indicate a risk of suicide CFS patients with adult ADHD had a higher risk of suicide than CFS patients without ADHD
CFS: Chronic fatigue syndrome; ADHD: Attention-deficit/hyperactivity disorder; ASRS: Adult Self-Report Scale; EuroADAD: European Version of the Adolescent Assessment Dialogue; BDI: Beck Depression Inventory; SCID-I-CV: Structured Clinical Interview for DSM-IV Axis I Disorders, Clinician Version; DIVA: Diagnostic Interview for ADHD in Adults; CSS: Current Symptoms Scale–Self-Report Form; HDSQ: Hopelessness Depression Symptom Questionnaire-Suicidality Subscale; CAADID: Conners’Adult ADHD Diagnostic Interview for DSM-IV.
The 26 papers were written in 16 countries on four continents. Of the 26 studies, only two had a longitudinal design. Detailed information on the origin, design, sample and instruments of the studies can be found in Tables 1-3.
Is ADHD more common in people who are suicidal?
Table 1 summarizes the three studies on ADHD in suicidal patients[24-26].
Is suicide more prevalent in people with ADHD?
Table 2 includes the 14 studies, which examines suicidality in patients with ADHD[27-40].
Which other identifiable risk factors can be associated with suicide in ADHD?
Gender differences in suicidality and ADHD: Examining the gender distribution of ADHD cases among suicidal patients, only one study provided relevant data[24]: 8.6% of suicidal male adolescents had ADHD, and 4.7% of suicidal female adolescents had ADHD.
Focusing on the gender differences in suicidal cases among ADHD patients, in the above-described 12 papers, which examined the prevalence of suicidality among patients with ADHD, three studies focused on gender differences[27,35,37], and one study enrolled only girls[39].
Regarding suicidal ideation, Mayes et al[37] found no differences between boys and girls with ADHD with suicidal ideation (18% and 11%, respectively). All three studies examined the gender of those who attempted suicide among ADHD patients, and two did not find differences[28,37]. Agosti et al[27] found that 52.9% of patients with ADHD who had previous suicide attempts were male, while the rate of males was 58.3% in patients with ADHD without previous suicide attempts. Mayes et al[37] found no differences between boys and girls with ADHD and suicidal ideation (7% and 3%, respectively). Ljung et al[35] found that the risk of suicide attempts among ADHD patients differed significantly by gender (χ2 = 1271.0; P < 0.001): The adjusted estimate was 2.93 (95%CI: 2.60-3.29) for males and 5.41 (95%CI: 4.60-6.36) for females. Only one study examined gender differences in ADHD patients who completed suicide[35] and found no gender differences.
Suicidality in patients with psychiatric disorders who have ADHD comorbidity: Table 3 summarizes the seven studies among the 26, which investigated ADHD, as a comorbid condition of other psychiatric disorders, and its association with suicidality[30,41-46].
Suicidality in ADHD patients who have psychiatric comorbidity: From the 26 papers of this review, the 10 studies, which investigated comorbidity in ADHD patients with suicidality are presented in Table 4[27,28,35-39,47,48].
Table 4 Included relevant articles examining attention-deficit/hyperactivity disorder and suicidality from January 2011 to January 2015: Suicidality in attention-deficit/hyperactivity disorder patients who have psychiatric comorbidity
Suicidality in ADHD patients who have psychiatric comorbidity
Ref. Country Study design Sample Population at onset Population’s age at onset Measures for ADHD, comorbid conditions and suicidality Main findings
Agosti et al[27] United States Cross-sectional Clinical sample Current ADHD: 365 adults: With Suicide attempts: n = 59 No suicide attempts: n = 306 Age range: 18-66 yr CIDI, ACDS, DIS-IV Sixteen percentage of participants with current ADHD diagnosis had previous suicide attempt. While ADHD increased the risk of previous suicide attempt only 1.5 fold, having one or more comorbid disorders increased the risk of previous suicide attempt 4 to 12 fold
Balazs et al[28] Hungary Cross-sectional Clinical sample ADHD and subthreshold ADHD children: n = 220 ADHD and subthreshold ADHD adolescents: n = 198 Children: Age range: 3-11 yr Mean age: 7.67 yr (SD = 2.03) Adolescents: Age range: 12-17 yr Mean age: 14.31 yr (SD = 1.67) MINI-KID The relationship between ADHD and suicidality was fully mediated by comorbid psychiatric disorders. In children, symptoms of anxiety disorders mediated this relationship, while in the adolescent group, symptoms of major depressive episode, dysthymia, and substance abuse/dependence were found to be significant mediators
Daviss et al[47] Lebanon Cross-sectional Clinical sample Youth with ADHD: n = 101 (male ratio: 63.4%) Lifetime SBs n = 28 (male ratio: 42.9%) No lifetime SBs: n = 73 (male ratio: 71.2%) Age range in the whole sample: 11-18 yr Lifetime SBs: Mean age: 14.6 yr (SD = 2.1) No lifetime SBs: Mean age: 13.5 yr (SD = 1.8) K-SADS-PL ADHD Rating Scale In this ADHD sample, after controlling for the age, female sex, and comorbid disorders, lifetime SB remained significantly associated with parent-child conflict, and impairment in nonacademic domains of function and breadth of exposure to victimization events Past and current ADHD symptoms and signs were not associated with lifetime SB
Ljung et al[35] Sweden Cross-sectional Patient and prescribed drug registers and population-based registers ADHD: n = 51707 (male ratio: 69.8%) Control: n = 258535 Age range: 3-40 yr Discharge diagnosis of ADHD Participants with ADHD had an increased risks of both attempted and completed suicide compared with control participants. This result was the same even after adjusting for comorbid psychiatric conditions. While the highest familial risk was reported among first-degree relatives, lower risk was observed among more genetically distant relatives. The results suggests that shared genetic factors are important for this association
Mayes et al[36] United States Cross-sectional Community and clinical sample 1706 children and adolescents with psychiatric disorders and typical development: ADHD-C: n = 566 (male ratio: 74.6%) ADHD-I: n = 235 (male ratio: 57.4%) Other psychiatric disorders (autism, depression/ anxiety, eating disorder, intellectual disability): n = 719 (male ratio: 67.2%) Typical: n = 186 (male ratio: 43.5%) Age range: 6-18 yr All participants had a clinical diagnosis of ADHD made by a licensed PhD psychologist. The clinical diagnosis was based on a comprehensive psychological evaluation including diagnostic inter- views with the parent and child, parent and teacher rating scales, review of educational and medical records, extensive psychological testing PBS All psychiatric groups had far more suicide behavior than typically developed children. ADHD-C: 20.7% had suicide ideation, 6.0% attempt ADHD-I: 7.3% had suicide ideation, 2.6% attempt
Mayes et al[37] United States Cross-sectional Clinical sample Children and adolescents with ADHD: n = 925 (male ratio: 68.5%) ADHD-C: n = 666 ADHD-I: n = 259 Age range: 3-16 yr Mean age: 8.8 yr (SD = 2.6) All participants had a clinical diagnosis of ADHD made by a licensed PhD psychologist. The clinical diagnosis was based on a comprehensive psychological evaluation including diagnostic inter- views with the parent and child, parent and teacher rating scales, review of educational and medical records, extensive psychological testing PBS - suicide ideation and attempt items For the total sample with ADHD, 15.8% had suicide ideation (sometimes or more) and 5.5% had attempts. Ideation and attempts were more than twice as prevalent among participants with ADHD-C than among participants with ADHD-I. ADHD-C: 19% had suicide ideation, 7% attempt ADHD-I: 7% had suicide ideation, 3% attempt Those, who had ADHD alone: 6% had suicide ideation and 2% had suicide attempt
Park et al[38] South Korea Cross-sectional Community sample A total of 6081 subjects: Non-ADHD symptom group: n = 6012 ADHD symptom group: n = 69 Age range: 18-59 yr K-CIDI Adult ADHD Self-Report Scale Those, who had ADHD + co-occurring sadness and ODD, 46% had ideation and 21% had attempts Adult ADHD symptoms are significantly associated with lifetime suicidality. However, the association disappeared after adjusting for other comorbid psychiatric disorders
Swanson et al[39] United States Longitudinal: 10 yr: First 5 yr follow up and second 10 yr follow-up Community and clinical sample ADHD girls: n = 140 Non-ADHD girls: n = 88 Age range: 6-12 yr at ascertainment Mean age at 5 yr follow-up: 14.2 yr Mean age at 10 yr follow-up: 19.6 yr (range 17-24 yr) At ascertainment: DISC-IV First follow up: SNAP-IV, Second follow up: SIQ, Barkley Suicide Questionnaire, DISC-IV-YA Women with a childhood diagnosis of ADHD-C, compared with those with ADHD-I and control group, were at higher risk for suicide attempts. Furthermore, women with a persistent ADHD diagnosis were at higher risk than women with a transient diagnosis and the control group
Taylor et al[48] New Zealand Cross-sectional Community sample 66 adults (43 men, 23 women ADHD: n = 35 (male ratio: 65.7%) Non-ADHD: n = 31 (male ratio: 64.5%) Age range: 18-65 yr Mean age: 31.9 yr (SD = 1.6) CAARS DSHI SCID-I (suicidality) CAADID There was a significant associations between ADHD symptom severity and self-reported suicidal ideation and suicide attempts. These associations between suicidal behaviours and ADHD symptom severity were significantly and differentially mediated by psychosocial variables such as comorbidities (mood, anxiety, drug, and alcohol abuse disorders) and emotion-focussed coping style
SB: Suicidal behavior; ADHD: Attention-deficit/hyperactivity disorder; CIDI: Composite International Diagnostic Interview; ACDS: Adult ADHD Clinical Diagnostic Scale; DIS-IV: The Diagnostic Interview Schedule for DSM-IV; MINI-KID: Mini-International Neuropsychiatric Interview for children and adolescents; K-SADS-PL: Schedule for Affective Disorder and Schizophrenia for School-Age Children- Present and Lifetime Version; K-CIDI: Korean version of Composite International Diagnostic Interview; DISC-IV-YA: Diagnostic Interview Schedule for Children 4th ed., Young Adult version; SNAP-IV: Swanson, Nolan, and Pelham Rating Scale; SIQ: Self-Injury Questionnaire; CAADID: Conners’Adult ADHD Diagnostic Interview for DSM-IV; CAARS: Conners’ Adult ADHD Rating Scale; DSHI: Deliberate Self-Harm Inventory; ADHD-C: ADHD combined type; ADHD-I: ADHD inattentive type, ADHD-HKS Questionnaire.
Assessments for measuring ADHD, suicidality and comorbid conditions
Assessments for measuring ADHD: Table 5[49-55] summarizes assessments for measuring ADHD.
Table 5 Assessments for measuring attention-deficit/hyperactivity disorder
Ref. Scale Abbriviation
[49] Adult ADHD Clinic Diagnostic Scale ACDS
[50] Adult Self-Report Scale ASRS
[51] Adult ADHD DSM-IV-Based Diagnostic Screening and Rating Scale, ADHD-C: ADHD combined type, ADHD-I: ADHD inattentive type, ADHD-HKS Questionnaire ADHD scale
[52] Conners’ Adult ADHD Diagnostic Interview for DSM-IV CAADID
[53] Conners’ Adult ADHD Rating Scale CAARS
[54] Diagnostic Interview for ADHD in Adults DIVA
[55] Strengths and Weaknesses of ADHD symptoms and Normal Behaviors SWAN
ADHD: Attention-deficit/hyperactivity disorder; DSM-IV: Diagnostic and statistical manual of mental disorders fourth edition; ADHD-HKS: Attention deficit hyperactivity disorder - hyperkinetic syndrome.
Assessments for measuring suicidality and comorbid conditions: Table 6[56-80] summarizes assessments for measuring suicidality and comorbid conditions.
Table 6 Assessments for measuring suicidality and comorbid conditions
Ref. Scale Abbriviation
[56] Beck Depression Inventory BDI
[57] Brief Symptoms Inventory BSI
[58] Brief Symptoms Rating Scale BSRS-5
[59] Composite International Diagnostic Interview CIDI
[60,61] Current Symptoms Scale-Self-Report Form CSS
[62] Deliberate Self-Harm Inventory DSHI
[63] Diagnostic Interview Schedule for DSM-IV DIS-IV
[64] Diagnostic Interview Schedule for Children DISC-IV
[65] Diagnostic Interview Schedule for Children 4th ed., Young Adult version DISC-IV-YA
[66,67] European Version of the Adolescent Assessment Dialogue EuroADAD
[68] Hopelessness Depression Symptom Questionnaire-Suicidality Subscale HDSQ
[69] Korean version of Composite International Diagnostic Interview K-CIDI
[70] Schedule for Affective Disorder and Schizophrenia for School-Age Children- Present and Lifetime Version K-SADS-PL
[71] Psychological Screening Test for Adolescents PSTA
[72] Rutter's Behaviour Scale for Children (Teacher’s Scale) Rutter B2
[73] Mini International Neuropsychiatric Interview MINI
[73,74] Mini International Neuropsychiatric Interview Kid MINI Kid
[75] Pediatric Behavior Scale PBS
[76,77] Structured Clinical Interview for DSM-IV Axis I Disorders, Clinician Version SCID-I-CV
[78] Structured Clinical Interview for DSM-III-R Personality Disorders SCID-II
[79] Self-Injury Questionnaire SIQ
[80] Swanson, Nolan, and Pelham Rating Scale 4th ed. SNAP-IV
DISCUSSION
This review of the last four years strengthens the recent finding that ADHD is related to high suicidality in all age groups and in both girls and boys.
Although our current systematic review was conducted only for the last four years, we still found 26 papers that presented data on ADHD and suicidality. Moreover, we know that several systematic review papers and overviews had been done previously. Impey et al[19], who performed a systematic search on the same topic, covering all studies up to January 2011, the starting point of our search period, found 25 papers. All of them support the view that research on the association of ADHD and suicidality is a subject of high and growing interest, and clinicians and researchers need to have access to up-to-date knowledge in this field.
The studies of this review are culturally diverse, as they come from four continents. This shows that this topic has relevance all over the world and that the conclusions can be used in wider aspects.
Regarding the age groups investigated on the topic of ADHD and suicidality, the studies have been balanced over the last four years: Exactly half of them investigated children/adolescents, and half of them examined adults. This reflects the growing interest in ADHD in adulthood among both healthcare professionals and researchers[81]. Considering the previous studies on this topic - which were included in the review of Impey et al[19] - a majority of them involved the 12-18 age group, although there were a few studies in older and younger age groups as well. Additionally, in their review, Impey et al[19] concluded that, based on the studies included in their review paper, age differences were not clearly definable. In this way, the current review extends our knowledge with further information on all age groups with ADHD and suicidality, including children under 12 and adults, and makes it possible to compare different age groups.
Systematically searching the literature of the last four years, we found only two studies that reported the prevalence data of ADHD among patients with suicidality[24,45]; however, there were a total of six studies addressing that study question in the review of Impey et al[19]. There were five in the review of James et al[18], but four of them were included in the review of Impey et al[19] as well. In both studies in the current review, the diagnoses of ADHD and suicidality were based on a clinician’s opinion. A very important and new result shown in our review is that one-quarter of the suicidal children under 12 years old had ADHD. The prevalence rate of ADHD among suicidal adolescents was lower (5.7%) than in children, and it was lower than in previous studies[19]. One possible explanation could be that these studies did not use either diagnostic interviews or screening tools for the diagnoses of ADHD and suicidality. All of them show that there is still limited data on the prevalence of ADHD among patients with suicidality; however, all of the studies performed found a high prevalence of ADHD in this population, especially among young children. Further studies are needed, but based on the current knowledge, we suggest a routine screening for ADHD patients with suicidal thoughts and attempts, with a special focus on young children.
Almost half of the papers reported prevalence data on suicidality in ADHD patients. The results strengthen the findings of previous studies[18-21] that there is a positive association between ADHD and suicidality, including completed suicides, attempts, as well as ideation. We would like to highlight that, in adolescence, based on the studies of the last four years, more than half of the patients with ADHD had suicidal thoughts, and this prevalence rate is even higher than what has been described previously[19]. It is important to note that even in adulthood, one third of ADHD patients had suicidal ideation. Based on these results, we suggest the introduction of routine screening questions on suicidal thoughts in outpatient/inpatient ADHD clinics, both for those specializing in adults and those specializing in children/adolescents. This improvement in clinical practice can be an important step towards suicide prevention.
The rate of previous suicide attempts was the highest (16%) in the adult ADHD age group; however, adolescents need attention in this respect as well, as almost one-tenth of ADHD patients in this age group had a previous suicide attempt. As one of the strongest predictors of a completed suicide is a previous suicide attempt, close follow-up of these ADHD patients could be of core importance in suicide prevention.
When we examined, which identifiable risk factors can be associated with suicide in ADHD, first we focused on gender. There are still a limited number of studies examining gender differences within this topic. The only study[24] that reported data on the gender distribution of suicidal patients with ADHD is in agreement with the conclusion of previous reviews[18,19] that ADHD is present more often among suicidal men than suicidal women. However, when we examined the prevalence of suicidality (e.g., ideation, attempts and completed suicides) in ADHD patients, two out of three of the studies did not find a difference between men and women[27,37], and one study reported an adjusted estimate for the risk of suicide attempts in females that was almost twice as high[35]. In his selected review paper, Nigg[21] reported that girls had an elevated risk of a suicide attempt as well; however, the author stated that boys have a higher risk of completed suicide among ADHD patients. It is important to note that there are very few studies that have focused on female patients with ADHD[82]. One of them was conducted during the search period of this review[39], while in the previous review on this topic, there were several studies in which only men were enrolled, as well as those in which both females and men were included[19]. Based on the currently available results, both females and males with ADHD need a special focus to recognize their possible suicide risk; however, further studies are needed to gain a better understanding of the gender differences in all age groups.
Second, when we examined identifiable risk factors, which can be associated with suicide in ADHD, we focused on comorbidities. One of the most exciting questions, which also has been raised in all of the previous review and summary papers[18-21], is whether there is a direct association between ADHD and suicidality or if ADHD increases the risk of suicide through comorbid conditions. In the current review, we examined two aspects of this question. First, we reviewed all of the papers within the examined period that measured the prevalence of ADHD in suicidal patients with other psychiatric disorders, such as mood disorders, schizophrenia, alcohol/drug intoxication and chronic fatigue syndrome. The results of all seven studies on this topic showed that the prevalence of suicidality is higher when psychiatric disorders are comorbid with ADHD than in their absence. These findings suggest that the presence of ADHD, as a comorbid condition, conveys an increased risk of suicide for patients with other psychiatric disorders. Second, we investigated the role of comorbidity in ADHD patients with suicidality. The majority of the studies (7/9) found that comorbid disorders mediate between suicidality and ADHD[27,36,38-41,49], which is in line with the conclusion of previous review papers[18-21]. It highlights the importance of raising clinicians’ awareness of the need to screen and treat comorbidity in ADHD, which may reduce suicidality as well.
These findings are limited in that only studies published in English and in Hungarian were included. Three potentially relevant studies were excluded because they were neither in English nor in Hungarian. The vast majority of the studies included in this review have a cross-sectional design, which limits the possible conclusions. Additionally, most of the studies that were conducted before this review paper have a cross-sectional design as well[19]. This should draw the attention of the researchers that, in the future, more studies are needed with a longitudinal design. Additionally, similar to the previous review of Impey et al[19], the measurement methods for both ADHD and suicidality in the studies included in the current review are very different, i.e., diagnostic interviews, rating questionnaires and clinician-made diagnoses - which means that a comparison of the numerical results is not possible.
In conclusion, our systematic highlights that the early recognition and treatment of ADHD - either as a comorbid condition or as a main diagnosis- and the co-occurring psychiatric disorders, can play an important role in the secondary prevention of suicide. Additionally, it could be useful to incorporate routine measurements of suicidality in the daily practice of ADHD clinics.
ACKNOWLEDGMENTS
This work was supported by OTKA K108336 grant. Judit Balázs was supported by the János Bolyai Research Scholarship of the Hungarian Academy of Sciences.
COMMENTS
Background
Recently, several studies have focused on attention-deficit/hyperactivity disorder (ADHD) as a possible psychiatric disorder that may serve as a suicide risk factor as well. This paper presents a systematic review of suicidality and ADHD as an extension of previous reviews for the search period and with study questions.
Research frontiers
Suicide prevention is a public health issue all over the world. As ADHD is one of the most prevalent psychiatric disorders among children and adolescents and in 40%-60% of the cases, it continues into adulthood. All additional knowledge on the possible association between ADHD and suicidality has high clinical importance and can add to suicide prevention.
Innovations and breakthroughs
Although this systematic review was conducted only for the last four years, the authors still found 26 papers that presented data on ADHD and suicidality.
Applications
This systematic review strengthens the finding that ADHD is related to high suicidality in all age groups and in both girls and boys. It highlights that the early recognition and treatment of ADHD - either as a comorbid condition or as a main diagnosis - and the co-occurring psychiatric disorders, can play an important role in the secondary prevention of suicide.
Terminology
Attention-deficit/hyperactivity disorder: ADHD is a neurodevelopmental disorder with ongoing pattern of inattention and/or hyperactivity-impulsivity that interferes with functioning or development; Suicidality: It includes suicidal thought, suicidal plan, suicidal attempt and completed suicide; Systematic review: A systematic review is a type of literature review which aims to provide a thorough, complete, exhaustive summary of current literature relevant to a research question.
Peer-review
The authors have reviewed the evidence for an association between ADHD and suicide. This is a descriptive review that does not include meta-analysis.
Conflict-of-interest statement: Author Judit Balazs has received a speaker honorarium from E. Lilly Company and she is a member of the Advisory Board committee of E. Lilly Company. Author Agnes Kereszteny declares that she has no conflict of interest.
Data sharing statement: The current manuscript does not describe a study, it is a systematic review.
Manuscript source: Invited manuscript
Specialty type: Psychiatry
Country of origin: Hungary
Peer-review report classification
Grade A (Excellent): A
Grade B (Very good): B
Grade C (Good): 0
Grade D (Fair): D
Grade E (Poor): 0
Peer-review started: November 2, 2016
First decision: November 30, 2016
Article in press: January 18, 2017
P- Reviewer: Gazdag G, Poulton A, Pivac N S- Editor: Ji FF L- Editor: A E- Editor: Wu HL
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World J PsychiatryWJPWorld Journal of Psychiatry2220-3206Baishideng Publishing Group Inc jWJP.v7.i1.pg6010.5498/wjp.v7.i1.60Meta-AnalysisConsequences of bullying victimization in childhood and adolescence: A systematic review and meta-analysis Moore Sophie E Norman Rosana E Suetani Shuichi Thomas Hannah J Sly Peter D Scott James G Sophie E Moore, Peter D Sly, Child Health Research Centre, the University of Queensland, South Brisbane, QLD 4101, AustraliaRosana E Norman, Institute of Health and Biomedical Innovation, Queensland University of Technology, Kelvin Grove, QLD 4059, AustraliaRosana E Norman, School of Public Health and Social Work, Queensland University of Technology, Kelvin Grove, QLD 4059, AustraliaShuichi Suetani, Queensland Centre for Mental Health Research, the Park Centre for Mental Health, Wacol, QLD 4076, AustraliaShuichi Suetani, Faculty of Medicine, the University of Queensland, Herston, QLD 4029, AustraliaHannah J Thomas, James G Scott, the University of Queensland Centre for Clinical Research, the University of Queensland, Herston, QLD 4029, AustraliaJames G Scott, Metro North Mental Health, Royal Brisbane and Women’s Hospital, Herston, QLD 4029, AustraliaAuthor contributions: Norman RE and Scott JG designed the study, supervised the systematic review and meta-analysis and supervised the writing of the manuscript; Moore SE and Suetani S conducted the systematic review; Moore SE conducted the meta-analysis and wrote the first draft of the manuscript; Thomas HJ drafted sections of the manuscript related to bullying measurement and supervised the manuscript content; all authors contributed to and approved the final manuscript.
Correspondence to: James G Scott, Associate Professor, the University of Queensland Centre for Clinical Research, the University of Queensland, Bowen Bridge Rd, Herston, QLD 4029, Australia. james.scott@health.qld.gov.au
Telephone: +61-73-6368111 Fax: +61-73-6361166
22 3 2017 22 3 2017 7 1 60 76 13 9 2016 4 12 2016 27 12 2016 ©The Author(s) 2016. Published by Baishideng Publishing Group Inc. All rights reserved.2016Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/AIM
To identify health and psychosocial problems associated with bullying victimization and conduct a meta-analysis summarizing the causal evidence.
METHODS
A systematic review was conducted using PubMed, EMBASE, ERIC and PsycINFO electronic databases up to 28 February 2015. The study included published longitudinal and cross-sectional articles that examined health and psychosocial consequences of bullying victimization. All meta-analyses were based on quality-effects models. Evidence for causality was assessed using Bradford Hill criteria and the grading system developed by the World Cancer Research Fund.
RESULTS
Out of 317 articles assessed for eligibility, 165 satisfied the predetermined inclusion criteria for meta-analysis. Statistically significant associations were observed between bullying victimization and a wide range of adverse health and psychosocial problems. The evidence was strongest for causal associations between bullying victimization and mental health problems such as depression, anxiety, poor general health and suicidal ideation and behaviours. Probable causal associations existed between bullying victimization and tobacco and illicit drug use.
CONCLUSION
Strong evidence exists for a causal relationship between bullying victimization, mental health problems and substance use. Evidence also exists for associations between bullying victimization and other adverse health and psychosocial problems, however, there is insufficient evidence to conclude causality. The strong evidence that bullying victimization is causative of mental illness highlights the need for schools to implement effective interventions to address bullying behaviours.
BullyingVictimizationSystematic reviewMeta-analysisChildAdolescent
==== Body
Core tip: There is convincing evidence of a causal association between exposure to bullying victimization in children and adolescents and adverse health outcomes including anxiety, depression, poor mental health, poor general health, non-suicidal self-injury, suicidal ideation and suicide attempts. It is probable that bullying victimization also causes an increased risk of cigarette smoking and illicit drug use. This review highlights that bullying victimization is associated with a wide and diverse range of problems and reinforces the need for effective interventions to be implemented in schools to address the high prevalence of children and adolescents engaging in bullying behaviours.
INTRODUCTION
Bullying victimization among children and adolescents is a global public health issue, well-recognised as a behaviour associated with poor adjustment in youth[1]. There is evidence suggesting bullying victimization in children and adolescents has enduring effects which may persist into adulthood[2-4]. Bullying victimization is most commonly defined as exposure to negative actions repeatedly and over time from one or more people, and involves a power imbalance between the perpetrator(s) and the victim[5]. Traditional bullying includes physical contact (pushing, hitting) as well as verbal harassment (name calling, verbal taunting), rumour spreading, intentionally excluding a person from a group, and obscene gestures. In recent years cyberbullying has emerged as a significant public health problem[5-8].
The estimated prevalence of bullying victimization is wide-ranging, with 10% and 35% of adolescents experiencing recurrent bullying victimization[9-16]. While contextual and cultural differences influence prevalence estimates[17], this variation is most frequently explained by differences in measurement strategy[18-20]. As a result, researchers continue to call for greater consensus in the definition and measurement of bullying behaviours[17,21,22]. Cook et al[17] examined the variability in prevalence of bullying victimization in a meta-analysis, and more recently Modecki et al[20] synthesised studies measuring both traditional bullying and cyberbullying. Mean prevalence was 36% for traditional bullying victimization and 15% for cyberbullying victimization[20]. There was significant overlap between bullying victimization in traditional and online settings[20]. A meta-analysis by Kowalski et al[23] showed that the strongest predictor of cyber-victimization was traditional bullying victimization.
Many studies have examined adverse health and psychosocial problems associated with bullying victimization. Those most commonly reported are mental health problems, specifically depression, anxiety, self-harm, and suicidal behaviour[2,14,24-28]. Over the past two decades researchers have conducted a number of systematic reviews to examine the relationship between bullying victimization and ill mental health.
The first systematic investigation by Hawker and Boulton[1] was a meta-analysis of cross-sectional studies of peer victimization published between 1978 and 1997. The authors reported victimization was significantly associated with depression, loneliness, reduced self-esteem and self-concept, as well as anxiety. To understand the temporal sequence between peer victimization and mental health problems, Reijntjes and colleagues conducted a pair of meta-analyses of longitudinal studies to examine internalizing (depression, anxiety, withdrawal, loneliness, and somatic complaints) and externalizing behaviours (aggression and delinquency) and peer victimization[29,30]. They examined two prospective paths: (1) peer victimization at baseline and changes in internalizing and externalizing problems at a second time point; and (2) internalizing and externalizing problems at baseline and changes in peer victimization at follow-up. The two meta-analyses demonstrated internalizing and externalizing behaviours are both antecedents and consequences of bullying victimization[29,30].
Another meta-analytic review on bullying victimization and depression by Ttofi et al[31] found those children who were bullied at school were twice as likely to develop depression compared to those who had not been bullied. In addition, another meta-analytic review found those children involved in any bullying behaviour were more likely to develop psychosomatic problems[32]. Finally, three systematic reviews have shown an association between bullying victimization and increased risk of adolescent suicidal ideation and behaviours[33-35].
In contrast to mental health, there is mixed evidence for the relationship between bullying victimization and substance use. Some studies report that bullying victimization is associated with a reduced risk of engaging in harmful alcohol use in later life[16,28], whereas others suggest that being bullied may result in an increased probability of later harmful alcohol use[36,37]. Similarly, some studies have shown an association between being bullied and later illicit drug use and smoking[36-39], whereas others have found no association at all[2,14,24,40].
The association between bullying victimization and psychosocial problems, such as academic achievement and school functioning/connectedness and criminal behaviour has also been examined. A meta-analysis by Nakamoto and Schwartz[41] found a small but significant negative association between bullying victimization and academic achievement. However, Kowalski et al[23] found no significant relationship between cyberbullying victimization and academic achievement. Another study found those exposed to bullying victimization in adolescence were at increased risk of involvement in criminal behaviour such as carrying a weapon[40].
There are now a large number of studies examining associations between bullying victimization and a wide range of adverse health and psychosocial problems. However, many of these have not been systematically examined and many existing systematic reviews did not include cyberbullying. Furthermore, although associations exist, it is unclear if there is a causal relationship. It is plausible that there are common factors that predispose individuals to being bullied in childhood but independently also increase the risk of adverse health and other psychosocial problems. Rigorous appraisal is required to consider both the possibility of a causal association but also other plausible explanations for any significant associations. Given the variation between studies, this study aimed to investigate adverse outcomes of both traditional and cyber bullying victimization and conduct a meta-analysis to summarize each association. Furthermore, we critically evaluated whether sufficient evidence existed to establish a causal relationship between bullying victimization and each of the adverse health and psychosocial problems. This is the first study to complete a summary of the evidence for all adverse health and psychosocial problems that are potentially a consequence of traditional and cyber bullying victimization.
MATERIALS AND METHODS
This study followed the recommendations from the PRISMA 2009 revision[42] and the guidelines outlined by the Meta-analysis of Observational Studies in Epidemiology[43] (Supplementary material S1). Methods and inclusion and exclusion criteria were specified in advance in the review protocol (Supplementary material S2).
Inclusion and exclusion criteria
This systematic review and meta-analysis included studies meeting the following inclusion criteria: (1) reported original, empirical research published in a peer reviewed journal; (2) examined the relationship between exposure to bullying victimization as a child or adolescent and one or more consequences of the bullying exposure; and (3) is a population based study. This study did not examine a particular type of bullying victimization therefore all direct and indirect forms of bullying including cyberbullying were included. Included studies reported odds ratios (ORs) and confidence intervals (CIs) comparing those exposed to bullying victimization and those not exposed to bullying victimization or, alternatively, provided information from which effect sizes (ORs and CIs) could be calculated between those exposed to bullying victimization and an outcome.
Search strategy
Four electronic databases (PsycINFO, ERIC, EMBASE and PubMed) were used to search for literature on the adverse correlates of bullying victimization as either a child or adolescent from inception up to 28 February 2015. The search was not restricted to the English language nor by any other means. The searches of the databases were conducted using the terms: “bullying”, “bullied”, “harassment”, “intimidation”, “victimization” along with “child” and “adolescent”. As this study aimed to examine all correlates that were potentially a consequence of bullying victimization, the search terms used in conjunction with those above were broader terms such as “outcome” “harm” “consequence” and “risk”. In addition, reference lists of selected studies were screened for any other relevant study and articles in languages other than English were translated (Supplementary material S2).
Data collection and quality assessment
The full text of articles that met all inclusion criteria were retrieved and examined. Data extracted using a data extraction template included publication details, country where study was conducted, methodological characteristics such as sample size and study design, exposure and outcome measures, type of bullying and frequency (Supplementary material S2). Each study was then subjected to a quality assessment in order for the reviewers to rate the quality of each study. Two reviewers independently reviewed the included articles and completed the quality assessment and any disagreements were resolved by a third reviewer. The quality assessment tool was based on the Newcastle-Ottawa Scale for assessing the quality of observational studies[44] as used by Norman et al[45] (Supplementary material S2).
Statistical analysis
Following the method used by Norman et al[45], MetaXL version 2.1[46], an add-in for Microsoft Excel was used in this study to conduct the meta-analysis. ORs were chosen as the summary measure. Heterogeneity was assessed using the Cochran’s Q and I2 statistics[47]. This meta-analysis used a quality effects model[48], a modified version of the fixed-effects inverse variance model that additionally allows greater weight to be given to studies of higher quality vs studies of lesser quality. The quality effects model avoids the limitation in random-effects models of returning to equal weighting irrespective of sample size if heterogeneity is large[47,48]. Furthermore, in order to address the effects of important study characteristics and explore heterogeneity this study conducted subgroup analyses, dependent on data availability, for sex of participants in the sample, geographic location and income level (high income vs low-to-middle income as per the World Bank classification criteria), severity of the bullying (frequent - at least once a month, vs sometimes - less than once a month), age of bullying victimization (before 13 years of age vs after 13 years of age), and type of study (prospective vs cross-sectional).
RESULTS
A total of 8231 articles were primarily identified by the search, of which 3270 were duplicates. Titles and abstracts for the 4961 remaining unduplicated references were reviewed and 15 additional articles were found from reference lists. From reviewing the title and abstracts a further 4659 articles were excluded. This left 317 articles meeting the following criteria: (1) original research extracted from a peer reviewed journal; and (2) examined the bullying victimization as a child or adolescent and one or more outcomes. Of the 317 articles reviewed, a further 152 articles were excluded as they did not use a population based sample or did not report enough information to calculate an effect size. The remaining 165 articles provided evidence of an effect size for bullying victimization and an outcome (Figure 1) - either odds ratio with confidence intervals or provided data which enabled the calculation of effect sizes. The majority (n = 142) were from high income regions. There were far fewer studies (n = 22) from low- and middle-income countries, and only one study utilized cross-national samples from different income-level countries. Of the articles included, 57 had a prospective cohort design and the remaining 108 were cross-sectional. The majority of studies measured self-reported bullying victimization. Some were from samples collected from a state or regions where as others were nationally representative (Supplementary material S3).
Figure 1 PRISMA flow diagram showing process of study selection for inclusion in systematic review and meta-analyses.
Bullying victimization in children and adolescents and mental health
Bullying victimization in children and adolescents was associated with a wide range of adverse mental health outcomes (Table 1) including poor mental health (OR = 1.60; 95%CI: 1.42-1.81), syndromes such as depression and anxiety, and symptoms and behaviours such as psychotic symptoms, suicidal ideation and attempts. Specifically, those exposed to bullying victimization had an increased risk of depression (OR = 2.21; 95%CI: 1.34-3.65). This association remained significant for all the sub-group analyses including prospective studies, age bullying occurred, sex and severity of the bullying. A dose response existed between being “sometimes bullied” and “frequently bullied” and depression (OR = 1.78; 95%CI: 1.39-2.28 and OR = 3.26; 95%CI: 2.45-4.34 respectively). In comparing high- and low-to-middle income countries, there was no significant difference in the odds of developing depression. Those exposed to bullying victimization were significantly more likely to experience anxiety (OR = 1.77; 95%CI: 1.34-2.33) and exposure to bullying victimization was associated with a wide range of anxiety spectrum disorders such as social phobia and post-traumatic stress disorder. This association remained after conducting subgroup analyses including study type, sex and severity of the bullying; however, the association between bullying victimization and anxiety was not significant in children under 13 years (Table 1).
Table 1 Associations between bullying victimization in children and adolescents and mental health outcomes
Data points Pooled OR 95%CI lower bound 95%CI upper bound Cochran’s Q I² (%) Test for heterogeneity (P value)
Poor mental health
Pooling all 39 1.6 1.42 1.81 303.79 87.49 < 0.01
Study type
Retrospective/cross-sectional 25 1.8 1.44 2.25 211.78 88.67 < 0.01
Prospective cohort 14 1.39 1.29 1.49 22.12 41.24 0.05
Sex
Male 3 2.49 1.86 3.32 0.44 0 0.8
Female 3 2.38 1.41 4 6.95 71.22 0.03
Twins 3 1.41 1.27 1.56 2.5 20.09 0.29
Severity of bullying
Sometimes 8 1.5 1.27 1.76 47.68 85.23 < 0.01
Frequent 8 1.52 1.18 1.95 51.4 86.38 < 0.01
Anxiety
Pooling all 58 1.77 1.34 2.33 3816.23 98.51 < 0.01
Anxiety 32 1.56 1.39 1.75 434.61 92.87 < 0.01
Social phobia 8 2.48 1.59 3.86 11.01 36.41 0.14
Generalised anxiety disorder 2 2.83 1.38 5.84 0.11 0 0.74
PTSD 12 6.41 1.93 21.22 497.11 97.79 < 0.01
Specific phobia 1 2.4 1 5.6 - - -
Separation anxiety disorder 1 4.6 2 10.6 - - -
Panic disorder 1 3.1 1.5 6.5 - - -
Agoraphobia 1 4.6 1.7 12.5 - - -
Study type
Retrospective/cross-sectional 39 2.02 1.21 3.38 3697.48 98.97 < 0.01
Prospective cohort 19 1.29 1.06 1.55 84.03 78.58 < 0.01
Age of bullying
Less than 13 yr 13 1.4 0.58 3.41 123.12 90.25 < 0.01
Older than 13 yr 45 1.81 1.29 2.56 3688.82 98.81 < 0.01
Sex
Male 16 1.84 1.3 2.59 112.23 86.63 < 0.01
Female 15 2.46 1.74 3.48 124.39 88.74 < 0.01
Severity of bullying
Sometimes 7 1.46 1.06 2 43.41 86.18 < 0.01
Frequent 25 2.47 1.94 3.14 122.47 80.4 < 0.01
Geographic location and income level
Low-to-middle income 22 2.41 1.75 3.32 175.97 88.07 < 0.01
High income 36 1.67 1.24 2.25 3441.17 98.98 < 0.01
Depression
Pooling all 92 2.21 1.34 3.65 14525.32 99.37 < 0.01
Major depressive disorder 2 2.27 0.68 7.57 2.07 51.63 0.15
Study type
Retrospective/cross-sectional 63 1.95 1.24 3.07 2594.97 97.61 < 0.01
Prospective cohort 29 3.03 1.31 6.98 4583.05 99.39 < 0.01
Age of bullying
Less than 13 yr 36 2.11 1.63 2.72 544.9 93.58 < 0.01
Older than 13 yr 56 2.29 1.24 4.23 13806.72 99.6 < 0.01
Sex
Male 27 2.07 1.48 2.89 443.84 94.14 < 0.01
Female 21 2.13 1.18 3.86 313.5 93.62 < 0.01
Severity of bullying
Sometimes 15 1.78 1.39 2.28 78.61 82.19 < 0.01
Frequent 28 3.26 2.45 4.34 224.43 87.97 < 0.01
Geographic location and income level
Low-to-middle income 13 2.53 1.75 3.68 143.98 91.67 < 0.01
High income 79 2.15 1.26 3.68 14351.72 99.46 < 0.01
Psychotic symptoms
Specific psychiatric symptoms 6 2.07 1.49 2.87 20.57 75.69 < 0.01
Non-clinical psychotic experiences 9 2.68 2.03 3.54 15.1 47.03 0.06
Psychotic symptoms 5 2.73 1.97 3.77 10.86 63.16 0.03
Personality disorders
Anti-social personality disorder 2 0.58 0.15 2.28 2.53 60.48 0.11
Borderline personality disorder 3 2.2 1.4 3.46 4.8 58.31 0.09
Eating disorders
Bulimia nervosa 1 3 1.4 6.2 - - -
Anorexia nervosa 1 0.004 0 251 - - -
Non-suicidal self injury
Pooling all 30 1.75 1.4 2.19 749.02 96.13 < 0.01
Study type
Retrospective/cross-sectional 21 1.55 1.09 2.22 721.15 97.23 < 0.01
Prospective cohort 9 1.65 1.34 2.02 19.39 58.75 0.01
Sex
Male 6 4.86 3.35 7.07 13.56 63.12 0.02
Female 4 2.7 2 3.65 8.92 66.37 0.03
Twins 2 2.57 1.79 3.7 0.12 0 0.73
Severity of bullying
Sometimes 6 1.57 1.09 2.25 34.04 85.31 < 0.01
Frequent 7 2.52 1.6 3.97 54.49 88.99 < 0.01
Suicidal ideation
Pooling all 105 1.77 1.56 2.02 2093.5 95.03 < 0.01
Study type
Retrospective/cross-sectional 86 1.8 1.56 2.09 2037.46 95.83 < 0.01
Prospective cohort 19 1.68 1.38 2.05 38.98 53.82 < 0.01
Age of bullying
Less than 13 yr 22 1.85 1.48 2.3 74.4 71.77 < 0.01
Older than 13 yr 83 1.75 1.51 2.03 1984.06 95.87 < 0.01
Sex
Male 21 1.95 1.64 2.32 76.6 73.89 < 0.01
Female 18 2.15 1.84 2.52 33.15 48.72 0.01
Severity of bullying
Sometimes 16 1.53 1.28 1.82 35.19 57.38 < 0.01
Frequent 21 2.59 2.06 3.25 49.83 59.87 < 0.01
Geographic location and income level
Low-to-middle income 11 1.31 1.06 1.61 60.02 83.34 < 0.01
High income 94 1.8 1.43 2.26 1894.91 95.09 < 0.01
Suicide attempt
Pooling all 48 2.13 1.66 2.73 1110.46 95.77 < 0.01
Suicidal attempt/non-suicidal self injury 3 2.97 1.68 5.23 6.33 68.42 0.04
Study type
Retrospective/cross-sectional 40 2.03 1.46 2.84 1105.65 96.47 < 0.01
Prospective cohort 8 2.04 1.38 3.01 4.34 0 0.74
Age of bullying
Less than 13 yr 11 2.11 1.65 2.69 11.49 12.98 0.32
Older than 13 yr 37 1.52 0.82 2.83 579.75 93.79 < 0.01
Sex
Male 7 2.93 1.65 5.18 15.38 54.5 0.02
Female 7 2.89 1.52 5.49 24.23 71.11 < 0.01
Severity of bullying
Sometimes 9 2.19 1.71 2.8 7.52 0 0.48
Frequent 12 3.77 2.55 5.58 28.31 61.14 < 0.01
Geographic location and income level
Low-to-middle income 4 1.91 1.07 3.43 22.18 86.47 < 0.01
High income 44 2.17 1.69 2.8 1084.61 96.04 < 0.01
Behavioural problems
Pooling all 54 1.37 1.18 1.59 862.4 93.85 < 0.01
Study type
Retrospective/cross-sectional 29 1.18 0.99 1.41 311.21 91 < 0.01
Prospective cohort 25 1.56 0.94 2.58 413.53 94.2 < 0.01
Sex
Male 9 1.35 0.68 2.67 450.06 98.22 < 0.01
Female 7 1.99 0.97 4.1 88.07 93.19 < 0.01
Twins 2 1.19 0.94 1.5 7.31 86.31 0.01
Severity of bullying
Sometimes 8 1.95 0.92 4.1 243.71 97.13 < 0.01
Frequent 8 2.26 0.76 6.69 163.51 95.72 < 0.01
Externalising behaviours 20 1.29 1.12 1.5 157.09 87.9 < 0.01
Delinquent/deviant behaviour 24 1.99 1.24 3.2 423.78 94.57 < 0.01
Missed school 7 1.49 0.99 2.23 38.4 84.37 < 0.01
Disruptive behavioural disorders
Attention deficit hyperactivity disorder 1 2.6 0.8 8.5 - - -
Oppositional defiant disorder 1 0.8 0.3 2.5 - - -
Conduct disorder 1 2.6 0.8 8.8 - - -
Other mental health outcomes (not included above)
Nervousness 9 1.82 1.51 2.2 135.59 94.1 < 0.01
Powerlessness 2 1.06 0.95 1.18 1.64 39.18 0.2
Feeling low 7 2.26 1.66 3.08 299.47 98 < 0.01
Irritability or bad temper 7 1.82 1.51 2.2 125.07 95.2 < 0.01
Feel helpless 5 3.2 2.01 5.09 273.51 98.54 < 0.01
Feeling tense 3 3.07 2.06 4.56 3.02 33.75 0.22
Unhappy/sad 12 1.25 0.55 2.84 668.61 98.35 < 0.01
Worried 4 1.27 1.09 1.47 314.35 99.05 < 0.01
Afraid 3 2.68 1.18 6.09 9.49 78.92 0.01
Bullying victimization was also associated with non-suicidal self-injury (OR = 1.75; 95%CI: 1.40-2.19) and increased risk of suicidal ideation (OR = 1.77; 95%CI: 1.56-2.02) and the association remained significant for all subgroup analyses (Table 1). A dose response existed between being “sometimes bullied” and “frequently bullied” and suicide ideation (OR = 1.53; 95%CI: 1.28-1.82 and OR = 2.59; 95%CI: 2.06-3.25 respectively). Bullying victimization was associated with an increase in suicide attempts (OR = 2.13; 95%CI: 1.66-2.73). Subgroup analysis showed both males and females were approximately three times more likely to attempt suicide if they were bullied (OR = 2.93; 95%CI: 1.65-5.18 and OR = 2.89; 95%CI: 1.52-5.49 respectively). There was nearly a fourfold increase in suicide attempts for individuals who experienced frequent bullying victimization (OR = 3.77; 95%CI: 2.55-5.58) (Table 1). When comparing high income countries to those with low and middle income, the odds of bullying victims developing suicidal ideation or attempting suicide were similar.
Although bullying victimization in children and adolescents was associated with the pooling of all behavioural problems (OR = 1.37; 95%CI: 1.18-1.59), this association was not significant in prospective cohort studies and no dose-response was observed. Diagnoses of disruptive behavioural disorders were not associated with bullying victimization in children and adolescents (Table 1).
Bullying victimization in children and adolescents and substance use
Table 2 presents the associations between bullying victimization and substance use. When all studies were pooled together there was a significant association between bullying victimization and alcohol use (OR = 1.26; 95%CI: 1.00-1.58). A subgroup analysis showed a significant association between bullying victimization and the risk of tobacco use for prospective studies (OR = 1.62; 95%CI: 1.31-1.99). Furthermore, a dose response was present with frequent bullying victimization being associated with tobacco use (OR = 3.19; 95%CI: 1.19-8.58), whereas no significant association was found with those who were “sometimes bullied” (Table 2).
Table 2 Associations between bullying victimization in children and adolescents and substance use
Data points Pooled OR 95%CI lower bound 95%CI upper bound Cochran’s Q I² (%) Test for heterogeneity (P value)
Alcohol use
Pooling all 53 1.26 1.00 1.58 10328.18 99.5 < 0.01
Study type
Retrospective/cross-sectional 38 1.28 0.88 1.84 10256.15 99.64 < 0.01
Prospective cohort 15 1.19 0.87 1.62 67.87 79.37 < 0.01
Sex
Male 6 0.61 0.49 0.77 4.89 0.00 0.43
Female 4 0.88 0.50 1.57 6.36 52.86 0.1
Severity of bullying
Sometimes 6 1.72 0.84 3.50 86.17 94.20 < 0.01
Frequent 13 1.53 0.78 3.03 332.27 96.39 < 0.01
Frequency of alcohol consumption
Sometimes 24 1.52 1.08 2.13 8416.94 99.73 < 0.01
Frequent 29 0.99 0.86 1.14 251.81 88.88 < 0.01
Age of bullying
Less than 13 yr 16 1.23 0.93 1.63 1618.14 99.07 < 0.01
Older than 13 yr 37 1.31 0.96 1.80 6896.71 99.48 < 0.01
Geographic location and income level
Low-to-middle income 11 1.37 0.75 2.49 8328.21 99.88 < 0.01
High income 42 1.08 0.91 1.27 462.84 91.14 < 0.01
Tobacco use
Pooling all 35 1.36 0.96 1.92 418.71 91.88 < 0.01
Study type
Retrospective/cross-sectional 26 1.17 0.59 2.31 394.92 93.67 < 0.01
Prospective cohort 9 1.62 1.31 1.99 11.48 30.33 0.18
Sex
Male 3 0.97 0.59 1.58 8.23 75.7 0.02
Female 3 0.51 0.37 0.68 1.78 0 0.41
Severity of bullying
Sometimes 4 1.89 0.83 4.33 71.38 95.8 < 0.01
Frequent 4 3.19 1.19 8.58 39.85 92.47 < 0.01
Frequency of smoking
Sometimes 28 1.36 0.89 2.06 400.72 93.26 < 0.01
Frequent 7 1.35 1.00 1.84 16.28 63.16 0.01
Illicit drug use
Pooling all 34 1.41 1.10 1.81 677.62 95.13 < 0.01
Study type
Retrospective/cross-sectional 11 2.43 1.42 4.15 297.3 96.64 < 0.01
Prospective cohort 23 1.27 1.12 1.44 67.23 67.28 < 0.01
Sex
Male 7 1.04 0.81 1.33 32.84 81.73 < 0.01
Female 5 1.17 1.03 1.33 3.26 0.00 0.52
Severity of bullying
Sometimes 7 1.22 0.78 1.90 160.47 96.26 < 0.01
Frequent 8 1.14 0.43 3.00 465.43 98.50 < 0.01
Geographic location and income level
Low-to-middle income 5 4.05 2.18 7.55 98.61 95.94 < 0.01
High income 29 1.31 1.15 1.48 103.73 73.01 < 0.01
Cannabis only all 9 1.42 0.96 2.12 23.32 65.70 < 0.01
Study type
Retrospective/cross-sectional 1 2.46 1.53 3.95 - - -
Prospective cohort 8 1.36 0.90 2.05 18.14 61.41 0.01
Bullying victimization was associated with an increased risk of illicit drug use (OR = 1.41; 95%CI: 1.10-1.81). Subgroup analysis revealed that the association between bullying victimization and increased risk of using illicit drugs was significant in both cross-sectional (OR = 2.43; 95%CI: 1.42-4.15) and prospective studies (OR = 1.27; 95%CI: 1.12-1.44). A subgroup analysis also revealed bullying victims in low-to-middle income countries are at an increased risk of illicit drug use (OR = 4.05; 95%CI: 2.18-7.55) compared with bullying victims in high income countries (OR = 1.31; 95%CI: 1.15-1.48). No significant association was found in a sub group analysis examining cannabis and bullying victimization in children and adolescence (Table 2).
Bullying victimization in children and adolescents and other health outcomes
Table 3 presents the association between bullying victimization and other health outcomes. Bullying victimization was associated with increased risk of somatic symptoms, the most common being stomach ache (OR = 1.76; 95%CI: 1.53-2.03), sleeping difficulties (OR = 1.73; 95%CI: 1.46-2.05), headaches (OR = 1.64; 95%CI: 1.38-1.94), dizziness (OR = 1.64; 95%CI: 1.38-1.95), and back pain (OR = 1.67; 95%CI: 1.43-1.95). Bullying victimization was also associated with an increased risk of being overweight and obese (OR = 1.68; 95%CI: 1.21-2.33 and OR = 1.78; 95%CI: 1.42-2.21, respectively). These associations were significant for cross-sectional studies only and there was no dose response.
Table 3 Associations between bullying victimization in children and adolescents and other health outcomes
Data points Pooled OR 95%CI lower bound 95%CI upper bound Cochran’s Q I² (%) Test for heterogeneity (P value)
Somatic symptoms
Unspecified psychosomatic symptoms 25 2.00 1.54 2.60 232.02 89.66 < 0.01
Stomach ache 25 1.76 1.53 2.03 138.73 82.7 < 0.01
Sleeping difficulties 24 1.73 1.46 2.05 574.91 96 < 0.01
Headache 26 1.64 1.38 1.94 169.16 85.22 < 0.01
Bedwetting 3 2.51 1.44 4.37 4.93 59.45 0.08
Feeling tired 2 2.68 1.39 5.19 1.22 17.87 0.27
Poor appetite 2 2.23 1.60 3.12 0 0 0.95
Back pain 8 1.67 1.43 1.95 73.53 90.48 < 0.01
Skin problems 1 1.82 1.33 251 - - -
Dizziness 9 1.64 1.38 1.95 76.57 89.55 < 0.01
Eating and weight related problems
Binge eating 2 2.66 1.68 4.22 0.57 0 0.45
Non-diet soft drink consumption 1 1.21 1.04 1.41 - - -
Skips breakfast 6 1.41 1.20 1.65 11.89 57.94 0.04
Underweight
Pooling all 2 1.27 0.73 2.21 0 0 0.96
Sex
Male 1 1.28 0.69 2.37 - - -
Female 1 1.24 0.19 2.29 - - -
Overweight
Pooling all 14 1.68 1.21 2.33 82.69 84.28 < 0.01
Study type
Retrospective/cross- sectional 12 1.99 1.39 2.85 65.45 83.19 < 0.01
Prospective cohort 2 0.98 0.64 1.49 1.92 47.97 0.17
Sex
Male 7 1.22 0.99 1.49 8.04 25.4 0.23
Female 7 2.22 1.28 3.84 50.17 88.04 < 0.01
Severity of bullying
Sometimes 2 1.32 1.00 1.74 0.09 0 0.77
Frequent 6 1.14 0.88 1.47 7.37 32.2 0.19
Obese
Pooling all 13 1.78 1.42 2.21 14.68 18.28 0.26
Study type
Retrospective/cross-sectional 10 1.97 1.53 2.53 7.22 0 0.61
Prospective cohort 3 1.57 0.89 2.77 6.89 70.97 0.03
Sex
Male 6 1.94 1.45 2.60 4.88 0 0.43
Female 6 2.15 1.57 2.94 2.22 0 0.82
Severity of bullying
Sometimes 2 1.63 1.11 2.38 0.52 0 0.47
Frequent 6 2.09 1.59 2.75 5.26 4.86 0.39
Sexual behaviour problems
Teen parent 5 1.26 0.81 1.97 15.11 73.53 < 0.01
Risky sexual behaviour 4 2.28 0.95 5.48 23.43 87.2 < 0.01
Early onset of sexual activities 3 1.44 0.90 2.30 7.38 72.91 0.02
Pooling all 12 1.51 1.01 2.25 85.66 87.16 < 0.01
Study type
Retrospective/cross-sectional 3 1.77 0.42 7.52 54.97 96.36 < 0.01
Prospective cohort 9 1.34 0.98 1.84 23.88 66.51 < 0.01
Severity of bullying
Sometimes 2 0.81 0.51 1.28 2.46 59.32 0.12
Frequent 4 2.38 1.05 5.41 27.55 89.11 < 0.01
Health services utilised
Pooling all 16 1.20 0.99 1.45 34.37 56.36 < 0.01
Study type
Retrospective/cross-sectional 14 1.14 0.94 1.39 27.91 53.42 0.01
Prospective cohort 2 1.54 0.65 3.61 4.43 77.43 0.04
Sex
Male 7 1.17 0.95 1.43 3.54 0 0.74
Female 7 1.41 1.12 1.77 11.16 46.25 0.08
General medication use
Pooling all 12 1.16 0.80 1.70 117.98 90.68 < 0.01
Study type
Retrospective/cross-sectional 11 0.99 0.56 1.75 112.26 91.09 < 0.01
Prospective cohort 1 1.67 1.09 2.58 - - -
Sex
Male
Medication for headache 2 1.43 1.06 1.93 2.34 57.21 0.13
Medication for stomach-ache 2 1.09 0.72 1.65 1.9 47.5 0.17
Female
Medication for headache 2 1.19 0.98 1.45 1.33 24.79 0.25
Medication for stomach-ache 2 1.23 1.01 1.5 0.27 0 0.61
Severity of bullying
Sometimes 5 1.26 0.99 1.59 15.46 74.13 < 0.01
Frequent 5 1.72 1.11 2.67 24.9 83.93 < 0.01
Over the counter drug misuse 3 0.95 0.19 4.66 76.34 97.38 < 0.01
Psychotropic medication use
Pooling all 13 1.28 0.72 2.26 205.76 94.17 < 0.01
Study type
Retrospective/cross-sectional 11 0.95 0.32 2.8 195.34 94.88 < 0.01
Prospective cohort 2 1.31 0.66 2.6 5.61 82.18 0.02
Sex
Male
Medication for nervousness 2 1.32 0.42 4.1 14.98 93.32 < 0.01
Medication for sleeping 2 1.89 1.33 2.67 1.59 37.28 0.21
Female
Medication for nervousness 2 1.97 1.49 2.59 1.06 5.88 0.3
Medication for sleeping 2 1.83 1.42 2.36 0.27 0 0.6
Severity of bullying
Sometimes 6 1.66 1.26 2.18 18.54 73.04 < 0.01
Frequent 6 1.88 1.17 3.03 31.93 84.34 < 0.01
Prescription drug misuse 3 0.92 0.17 5.07 88.16 97.73 < 0.01
Poor general health
Pooling all 29 1.83 1.45 2.31 133.31 79 < 0.01
Study type
Retrospective/cross-sectional 22 1.71 1.21 2.42 112.06 81.26 < 0.01
Prospective cohort 7 1.56 1.07 2.28 19.72 69.57 < 0.01
Sex
Male 9 1.95 1.16 3.27 20.5 60.98 0.01
Female 9 2.36 1.11 5.04 52.78 84.84 < 0.01
Severity of bullying
Sometimes 4 2.16 1.10 4.26 9.15 67.21 0.03
Frequent 4 6.96 2.17 22.35 16.72 82.05 < 0.01
When all studies were pooled, bullying victimization in children and adolescents was associated with increased risk of sexual behaviour problems (OR = 1.51; 95%CI: 1.01-2.25) which included teenage pregnancy, early onset of sexual activities and risky sexual behaviour. Subgroup analyses were not significant with the exception of those frequently bullied. Although bullying victimization was associated with increased likelihood of poor general health (OR = 1.83; 95%CI: 1.45-2.31) and this association persisted when restricted to prospective cohort studies (OR = 1.56; 95%CI: 1.07-2.28). There was no consistent increase in utilisation of health services or medications in those exposed to bullying victimization during childhood or adolescence (Table 3).
Bullying victimization in children and adolescents and academic and social functioning
The association between bullying victimization and functioning at school was inconsistent. There was a robust association between bullying victimization in childhood or adolescence and poor academic achievement. Those who had exposure to bullying victimization were more likely to have poor academic achievement (OR = 1.33; 95%CI: 1.06-1.66), whilst those with good academic achievement were less likely to have been exposed to bullying victimization (OR = 0.71; 95%CI: 0.60-0.85); however, all studies except one were cross-sectional. Bullying victimization was not associated with later financial or occupational functioning.
Similarly, there were inconsistent associations between bullying victimization and social problems. Those exposed were approximately twice as likely to report loneliness (OR = 1.89; 95%CI: 1.39-2.57) and poor life satisfaction (OR = 2.26; 95%CI: 1.41-3.60) and were significantly less likely to have a good quality of life (OR = 0.85; 95%CI: 0.78-0.93). Bullying victimization was not consistently associated with low self-esteem, social problems, or criminal behaviours (Table 4).
Table 4 Associations between bullying victimization and academic and social functioning
Data points Pooled OR 95%CI lower bound 95%CI upper bound Cochran’s Q I² (%) Test for heterogeneity (P value)
Poor school functioning
Pooling all 6 1.10 0.87 1.38 82 93.9 < 0.01
Study type
Retrospective/cross-sectional 3 1.24 1.22 1.27 0.33 0 0.85
Prospective cohort 3 0.90 0.76 1.08 8.15 75.46 0.02
Severity of bullying
Sometimes 1 0.96 0.88 1.04 - - -
Frequent 1 0.98 0.76 1.19 - - -
Academic achievement
Poor academic achievement
Pooling all 6 1.33 1.06 1.66 11.17 55.25 0.02
Study type
Retrospective/cross-sectional 6 1.33 1.06 1.66 11.17 55.25 0.02
Good academic achievement
Pooling all 4 0.71 0.60 0.85 8.81 65.97 0.07
Study type
Retrospective/cross-sectional 3 0.86 0.8 0.92 2.89 30.69 0.58
Prospective cohort 1 0.46 0.28 0.76 - - -
Sex
Male 2 1.24 0.88 1.74 2.49 59.8 0.65
Female 2 1.32 0.99 1.75 1.4 28.7 0.84
Severity of bullying
Sometimes 1 0.88 0.83 0.93 - - -
Frequent 1 0.80 0.70 0.93 - - -
Poor financial and occupational functioning
Pooling all prospective cohort 16 1.14 0.87 1.50 92.97 83.86 < 0.01
Severity of bullying
Sometimes 3 1.00 0.9 1.11 0.04 0 0.98
Frequent 3 0.81 0.61 1.07 2.68 25.32 0.26
Social isolation
Loneliness
Pooling all 13 1.89 1.39 2.57 3120.66 99.62 < 0.01
Study type
Retrospective/cross-sectional 13 1.89 1.39 2.57 3120.66 99.62 < 0.01
Sex
Male 4 2.58 1.62 4.10 222.21 98.65 < 0.01
Female 3 3.92 1.95 7.90 19.53 89.76 < 0.01
Severity of bullying
Sometimes 2 2.09 1.98 2.20 0.39 0 0.53
Frequent 4 4.12 2.24 7.60 23.32 87.13 < 0.01
Self esteem
Pooling all 14 0.99 0.92 1.07 93.73 86.13 < 0.01
Study type
Retrospective/cross-sectional 4 1.13 0.83 1.54 76.58 96.08 < 0.01
Prospective cohort 10 0.97 0.93 1.01 12.32 26.93 0.2
Sex
Male 5 0.96 0.88 1.06 20.65 80.63 < 0.01
Female 4 0.95 0.88 1.03 5.74 47.7 0.13
Severity of bullying
Sometimes 5 0.99 0.95 1.04 1.61 0 0.81
Frequent 5 0.95 0.87 1.04 9.65 58.54 0.05
Social problems
Pooling all 22 1.02 0.74 1.42 427.13 95.08 < 0.01
Study type
Retrospective/cross-sectional 5 2.86 1.42 5.76 38.09 89.5 < 0.01
Prospective cohort 17 0.89 0.74 1.06 72.36 77.89 < 0.01
Sex
Male 1 2.89 1.45 5.73 - - -
Female 1 8.10 4.60 14.26 - - -
Severity of bullying
Sometimes 3 0.9 0.83 0.96 0.5 0 0.78
Frequent 3 0.81 0.72 0.92 3.67 45.49 0.16
Criminal behaviour
Pooling all 33 1.04 0.78 1.39 133.36 76.01 < 0.01
Carrying a weapon 8 1.59 1.27 1.98 19.16 63.47 0.01
Violent offense/behaviour 6 1.25 1.01 1.56 2.46 0 0.78
Study type
Retrospective/cross-sectional 9 1.01 0.47 2.14 106.83 92.51 < 0.01
Prospective cohort 24 1.05 0.92 1.19 25.72 10.58 0.31
Sex
Male 11 1.00 0.82 1.22 13.78 27.43 0.18
Female 4 0.70 0.46 1.04 0.38 0 0.94
Severity of bullying
Sometimes 5 0.97 0.75 1.26 7.37 45.74 0.12
Frequent 8 1.22 0.86 1.74 16.33 57.13 0.02
Other outcomes reported
Good quality of later life 6 0.85 0.78 0.93 17.42 71.29 < 0.01
Poor life satisfaction 6 2.26 1.41 3.60 3.79 0 0.58
Problematic internet usage 1 2.36 1.58 3.54 - - -
Picked on by siblings 1 1.69 1.38 2.07 - - -
DISCUSSION
This paper provides the most comprehensive critical analysis of the association between bullying victimization and a wide range of health and psychosocial problems. The primary and sub-group analyses allow for interpretation of the evidence of causality within the Bradford-Hill Framework, based on the following: Biological plausibility, the temporal relationship of the association, strength and consistency of the association, the presence of a dose-response relationship, and whether an alternate explanation for the associations is possible[49]. We used the grading system developed by the World Cancer Research Fund[50] as used in the Global Burden of Disease study as a guideline for evaluation of the level of evidence.
Temporality
In this meta-analysis, both longitudinal (n = 57) and cross-sectional (n = 108) studies showed associations between bullying victimization and many adverse health and psychosocial problems. Prospective studies provided evidence of a temporal relationship showing bullying victimization preceded the later adverse consequences.
A temporal relationship exists between bullying victimization and outcomes such as anxiety, depression, non-suicidal self-injury, suicide ideation and suicide attempts. As poor mental health is also a known risk factor for bullying victimization[51], it is with caution we say that an independent temporal relationship exists between bullying victimization and these adverse mental health outcomes. Many studies did not control for pre-existing mental health and could be reporting a continuation of pre-existing psychopathology and not a direct outcome of the bullying victimization. Nonetheless, two recent studies have found that even when controlling for pre-existing mental health, bullying victimization was strongly associated with later adverse mental health consequences such as non-suicidal self-injury and depression[27,28].
Strength of the association
Both prospective and population-based studies demonstrated significant associations between bullying victimization and adverse health and psychosocial problems. After adjusting for confounding variables, there was generally a reduction in the strength of these associations. Furthermore, the magnitude of the associations diverged depending on the sub-group analysis performed. Despite some variability, bullying victimization was found to significantly increase the likelihood of mental ill health suggesting significant and robust associations.
Consistency of the association
Consistency of the associations between bullying victimization and mental ill health was demonstrated in the estimated effect sizes across studies. It is possible that publication bias affected the results for some of the outcomes. Direction of the association (as estimated through risk estimates) was consistent across different geographic regions, samples, study designs, and income levels investigated, particularly for anxiety, depression, non-suicidal self-injury, suicide ideation and suicide attempts (Supplementary material Figures S4, S5, S7, S8, S9). Inconsistent associations were observed for certain outcomes such as behavioural problems (Supplementaty material Figure S6).
Dose-response relationship
Available evidence suggests that experiencing more severe or frequent forms of adversity in childhood increases the risk of adverse outcomes compared to a lower exposure to adversity[45,52-56], particularly for mental health problems. Similarly, this study demonstrated a dose-response relationship between bullying victimization and detrimental effects on health, in particular for mental health problems. After summarizing the evidence through a meta-analysis, dose-response relationships were observed between bullying victimization and depression, suicide ideation, cigarette smoking and loneliness[45,52-56]. An increase in the dose of bullying victimization (frequent vs sometimes) resulted in non-significantly greater point estimates for other problems such as anxiety, medication use (general and psychotropic), suicide attempts and non-suicidal self-injury.
Plausibility
Due to a lack of animal models, the majority of inferences for biological plausibility arise from observational rather than experimental data. However, one model of social defeat in rats has been used to understand bullying victimization[57,58]. Two male rats are placed into a cage together, and after fighting, one rat becomes dominant and the other subordinate. The subordinate rat experiences social defeat and after a single experience demonstrates signs of stress. One study found that the subordinate rat demonstrated behaviours representative of depression in humans when exposed to multiple social defeats over several weeks[59].
Observational data has also been used to explain the association between bullying victimization in childhood and adolescence and the later development of mental health problems. First, early adverse experiences (i.e., bullying victimization) that occur during vulnerable developmental periods can cause neurobiological[60,61] or inflammatory[62] changes expressed as illnesses in later life[61]. Moreover, those individuals exposed to frequent bullying victimization who develop mental health problems may self-medicate their distress and negative emotions with alcohol, illicit drugs, medications, tobacco or disengaging from school.
Taking into account both the limited animal studies[57-59] and observational studies[60-62], it can be understood as to why bullying victimization can affect the immediate and long-term health and non-health related outcomes of the individual.
Consideration of alternate explanations
The relationship between bullying victimization and adverse health and psychosocial problems are thought to be complex and influenced by both genetics and environmental factors; however, there are limited twin studies available to inform these associations[27,63-66]. One study[64] found that being bullied in childhood is an environmentally mediated contributing factor to poor childhood mental health. Another found victimized twins were more likely to self-harm than their non-victimized twin sibling[27]. Exposure to bullying victimization has also been found to be associated with socioeconomic status[51,67] which is also known to play a role in the development of mental health problems and other health and non-health related outcomes[68].
It is further acknowledged that the association between bullying victimization and adverse outcomes is not necessarily an independent relationship. As early emotional and behavioural problems are known risk factors for bullying victimization, without adequate statistical adjustment, some studies may risk reporting pre-existing psychopathology rather than a direct outcome of bullying. The available evidence suggests a complex relationship between genetics and environment and neither can solely explain the relationship between bullying victimization and adverse outcomes. Even though some of the effects of bullying victimization on adverse outcomes reported may be a result of confounding factors, generally the association with mental health problems was significant after controlling for potential confounding factors.
Assessment of causality
Using the grading system developed by the World Cancer Research Fund (WCRF)[50] as a guideline for evaluation of the level of evidence, we concluded that there was “convincing evidence” for a causal relationship between bullying victimization and anxiety, depression, poor general and mental health, non-suicidal self-injury, suicide attempts, and suicide ideation. This evidence was based on a substantial number of epidemiological studies identified in this systematic review including prospective observational studies of sufficient size, duration, and quality showing consistent effects. In addition, the association was considered biologically plausible. We concluded that “probable evidence” of a causal relationship existed between exposure to bullying victimization and illicit drug and tobacco use based on the epidemiological evidence. Possible causal associations existed between bullying victimization and lower academic achievement, alcohol use, loneliness, obesity, overweight and psychosomatic symptoms. This evidence was based mainly on findings from cross-sectional studies and a few prospective studies showing inconsistent associations between exposure and disease. More studies are needed to support these tentative associations, which are also considered to be biologically plausible.
All other significant associations reported in this study were classified as having insufficient evidence of a causal relationship (Table 5). This is not suggesting that there is no causal relationship. Further research is needed to better examine if any associations that exist are causal or due to other confounding factors. Furthermore, the use of WCRF grading system, although appropriate for dietary risk factors, might not be adequate for psychosocial factors particularly newly emerging risks.
Table 5 Strength of evidence for a causal relationship between bullying victimization and adverse health or psychosocial problems
Strength of evidence Adverse health or psychosocial problem
Convincing Anxiety; depression; poor mental health; poor general health; non-suicidal self-injury; suicide attempts; suicide ideation
Probable Tobacco use; illicit drug use
Possible Alcohol use; psychotic symptoms; increased use of health services in females; lower academic achievement; social isolation; loneliness; psychosomatic symptoms, overweight and obesity
Insufficient Binge eating; bulimia nervosa; borderline personality disorder; behavioural problems; carrying a weapon; general medication use; health services sought; poor financial and occupational functioning; psychotropic medication use; poor school functioning; sexual behavioural problems; poor life satisfaction
Limitations
While we followed rigorous methodological steps, some limitations are notable. As studies with non-significant findings are less likely to be published, there may be a publication bias within this meta-analysis resulting in the association between bullying victimization and some adverse outcomes being overstated[69,70]. Additionally, inconsistencies would have occurred in the analysis due to methodological differences in the way bullying victimization is defined and measured throughout the studies as there is no consensus on the best way to measure bullying victimization[18,19]. In order to address this, a quality effects model was used giving higher scores to those studies which provided respondents with a definition and utilised a validated measure of bullying. There are also methodological issues in regards to the adverse outcomes reported, as some have been self-reported, while others were reported by teachers, parents, clinicians or through objective measures. This issue was also addressed with the use of a quality effects model in which higher quality scores were given to those studies where standardised validated diagnostic instruments were used to assess the outcome relative to those where outcomes were self-reported on a non-validated scale[44]. In spite of this methodology, the assessment of exposure to bullying and the assessment of a wide range of outcomes remains a challenge. In particular, there will always be some uncertainty pertaining to the measurement of bullying, especially when retrospectively reported as a result of the respondent’s subjective perception of the actions and behaviours of others.
As a research question involving bullying victimization can only be observational and not experimental, a further limitation of this meta-analysis are those limitations that come with observational studies[71]. First, we acknowledge the issue of confounding. It is appropriate to adjust for these confounders in the statistical analyses by either stratification or multivariate analysis[71]. Although many studies controlled for socio-demographic and other variables[2,27], some reported unadjusted odds ratios between bullying victimization and adverse outcomes, or provided only basic adjustment for sex and age[72,73]. This was addressed in this meta-analysis through the use of the quality score of studies where confounding factors were not adequately adjusted and by conducting further analyses where data were available[44]. Generally, after controlling for the effects of confounding variables, the associations between bullying victimization and adverse outcomes were attenuated. The majority of studies included in this meta-analysis did not identify individuals who were both victims and perpetrators of bullying. Previous research has suggested those who are both perpetrators and victims are at even greater risk of adverse mental health outcomes[28]; however, we were unable to confirm this with the current study.
In the majority of primary analyses of the association between bullying victimization and adverse outcomes, significant heterogeneity was present. This heterogeneity remained significant in most subgroup analyses even after controlling for study quality in the quality effects models[44].
In conclusion, evidence suggests a causal relationship between bullying victimization and mental health outcomes. There were also associations between bullying victimization and other adverse health and psychosocial problems which require further research to accurately measure the negative impact of bullying victimization and the broad health and economic costs. Through the implementation of school wide interventions that involve the entire school community (i.e., staff, students, and parents) bullying behaviour is considered a modifiable risk factor[25,74]. This review highlights the increased likelihood of a wide and diverse range of problems that are experienced by those exposed to bullying victimization. These findings reinforce the need for implementation of effective interventions in schools to address the high prevalence of children and adolescents engaging in bullying behaviours.
COMMENTS
Background
Bullying victimization (including traditional and cyberbullying) among children and adolescents is a global public health issue, well-recognised as a behaviour associated with poor adjustment in youth. There is evidence suggesting bullying victimization in children and adolescents has enduring effects which may persist into adulthood.
Research frontiers
There have been many studies examining the association between bullying victimization in children and adolescents and adverse health and social problems. However, many of these have not been systematically examined and existing systematic reviews did not include cyberbullying. Furthermore, although associations exist, it is unclear if there is a causal relationship.
Innovations and breakthroughs
The authors found convincing evidence of a causal relationship between bullying victimization in children and adolescents and adverse health outcomes including anxiety, depression, poor mental health, poor general health, non-suicidal self-injury, suicidal ideation and suicide attempts. It is probable that bullying victimization also causes an increased risk of cigarette smoking and illicit drug use.
Applications
Given the convincing evidence of a causal association, there is an urgent need for effective interventions to be implemented in schools to address the high prevalence of children and adolescents engaging in bullying behaviours.
Peer-review
This is an important topic on consequences of bullying victimization in childhood and adolescence. This area for sure needs more attention. The authors have done a great job presenting a large systematic review and meta-analysis of studies correlating the history of bullying victimization with different mental health problems in childhood and adolescence.
Conflict-of-interest statement: The authors have no conflicts of interest to declare.
Data sharing statement: No additional data is available.
Manuscript source: Invited manuscript
Specialty type: Psychiatry
Country of origin: Australia
Peer-review report classification
Grade A (Excellent): 0
Grade B (Very good): B, B
Grade C (Good): 0
Grade D (Fair): 0
Grade E (Poor): 0
Peer-review started: September 14, 2016
First decision: October 21, 2016
Article in press: December 28, 2016
P- Reviewer: Alavi N, Classen CF S- Editor: Ji FF L- Editor: A E- Editor: Wu HL
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World J PsychiatryWJPWorld Journal of Psychiatry2220-3206Baishideng Publishing Group Inc jWJP.v7.i1.pg810.5498/wjp.v7.i1.8Evidence-Based MedicineDifferences between British and Japanese perspectives on forensic mental health systems: A preliminary study Shiina Akihiro Tomoto Aika Omiya Soichiro Sato Aiko Iyo Masaomi Igarashi Yoshito Akihiro Shiina, Division of Medical Treatment and Rehabilitation, Chiba University Center for Forensic Mental Health, Chiba 260-8670, JapanAika Tomoto, Yoshito Igarashi, Division of Law and Psychiatry, Chiba University Center for Forensic Mental Health, Chiba 260-8670, JapanSoichiro Omiya, Social Psychiatry and Mental Health, Faculty of Medicine, University of Tsukuba, Ibaraki 305-8577, JapanAiko Sato, Chiba University Graduate School of Medicine, Chiba 260-8670, JapanMasaomi Iyo, Chiba University Graduate School of Medicine, Chiba 260-8670, JapanAuthor contributions: All the authors contributed to the manuscript.
Correspondence to: Akihiro Shiina, MD, PhD, Division of Medical Treatment and Rehabilitation, Chiba University Center for Forensic Mental Health, Inohana 1-8-1, Chiba 260-8670, Japan. olreia@yahoo.co.jp
Telephone: +81-43-2227171
22 3 2017 22 3 2017 7 1 8 11 9 7 2016 2 10 2016 21 11 2016 ©The Author(s) 2016. Published by Baishideng Publishing Group Inc. All rights reserved.2016Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/AIM
To clarify the differences in views on forensic mental health (FMH) systems between the United Kingdom and Japan.
METHODS
We conducted a series of semi-structured interviews with six leading forensic psychiatrists. Based on a discussion by the research team, we created an interview form. After we finished conducting all the interviews, we qualitatively analyzed their content.
RESULTS
In the United Kingdom the core domain of FMH was risk assessment and management; however, in Japan, the core domain of FMH was psychiatric testimony. In the United Kingdom, forensic psychiatrists were responsible for ensuring public safety, and psychopathy was identified as a disease but deemed as not suitable for medical treatment. On the other hand, in Japan, psychopathy was not considered a mental illness.
CONCLUSION
In conclusion, there are considerable differences between the United Kingdom and Japan with regard to the concepts of FMH. Some ideas taken from both cultures for better FMH practice were suggested.
Forensic mental healthMedical treatment and supervision actPsychopathyInternational comparisonQualitative research
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Core tip: Several differences regarding the policy and perspective in forensic mental health have found between British and Japanese forensic psychiatrists; psychopathy is deemed as a mental illness in the United Kingdom, but not in Japan; British forensic psychiatrists considered to be responsible for ensuring public safety, whereas Japanese do not think so.
INTRODUCTION
Forensic psychiatry is a sub-branch of psychiatry that deals with patients and problems at the interface of the legal and psychiatric systems[1]. Therefore, it follows that forensic psychiatric practice will vary from country to country. Many countries have established how to deal with mentally disordered offenders (MDOs), and this involves different disciplines[2].
Japan established the Forensic Mental Health (FMH) scheme, which coincided with the enforcement of the Medical Treatment and Supervision Act (MTSA; the Act on Medical Care and Treatment for the Persons Who Had Caused Serious Cases under the Condition of Insanity) in 2005[3]. For the establishment of the forensic psychiatric care scheme in Japan, the government referred to their English counterpart to a considerable extent. On the other hand, there are many differences between countries with regard to the cultural background and history of FMH and with regard to the criminal justice system.
Considering these facts, it is hypothesized that there are differences between the United Kingdom and Japan in basic perspectives on and the level of awareness with regard to forensic psychiatry. The aim of the present study was to clarify these differences by conducting a series of semi-structured interviews.
MATERIALS AND METHODS
We created an interview form, using which we conducted the semi-structured interviews. The items on the interview form were formulated by means of a discussion (among the authors) that was based on a relevant literature search. The interview included questions concerning people’s opinions on various issues pertaining to the current systems of and context surrounding FMH in the United Kingdom and Japan.
The interviewees were forensic psychiatrists who were engaged in FMH practice or research in either Japan or the United Kingdom. For our preliminary study, we used convenience sampling to select three participants from each country.
All participants provided written informed consent for participation in the study. The first author conducted the semi-structured interview with each participant. Each interview lasted for approximately forty-five minutes. We digitally recorded the interviews and examined their content after they had been conducted. We transcribed and qualitatively analyzed each comment made by the participants.
The study protocol was approved as an international comparison study of forensic psychiatry by the ethics committee of the Graduate School of Medicine of Chiba University on June 19, 2015.
RESULTS
All six participants answered all the questions that they were asked during the interview, and no questions were omitted.
The participants comprised the following individuals: One British and one Japanese professor of a department of FMH, one British and one Japanese clinical psychiatrist, each of whom was working in a forensic ward, and one British and one Japanese postgraduate student who had each worked in a forensic ward. The length of time for which the participants had worked as a medical doctor (mean, 27.7 years; 12-43) and for which they had worked in the area of FMH (mean, 16.2 years; 5-40) differed.
All three British participants identified psychopathy as a mental disorder, whereas the participants from Japan were neutral to or skeptical of this view. Notwithstanding this, almost all participants were opposed to treating psychopathic patients in a psychiatric ward. The British participants emphasized that there was a lack of evidence suggesting that treatment outcomes for psychopaths were desirable.
In the United Kingdom, seclusion and restraint were rarely implemented, except in the case of psychiatric emergency wards. In Japan, inpatients in general psychiatric wards were occasionally secluded and/or restrained, whereas those in MTSA inpatient facilities were seldom secluded and/or restrained. The British participants felt that seclusion and restraint should be a last resort for managing patients’ aggressive acts. In contrast, the Japanese participants felt that secluded circumstances could be beneficial for patients, for example, those who were bothered by auditory hallucinations, as it would help them become more aware of their psychotic symptoms.
Only one Japanese participant had been involved in masked medication. The Japanese participants were rather accepting of masked medication and considered it a necessary evil, except for one participant, who was absolutely against it; furthermore, all the British participants were against masked medication.
All three British participants stated that forensic psychiatrists should be responsible not just for patients’ treatment but also for public safety to some extent, whereas only one Japanese participant supported this view.
The British participants believed that the core competencies of forensic psychiatrists should be risk assessment and the management and understanding of the psychiatric basis of violent behaviors. In contrast, the Japanese participants felt that the core specialties of forensic psychiatrists should be the understanding of criminal responsibility and psychiatric testimony skills.
In the United Kingdom, the term of hospitalization is six months to two years in medium secure units (MSU), and five to seven years in high secure units (HSU), and in Japan, the MTSA usually requires MDOs to be hospitalized for two to three years in inpatient facilities.
All participants supported the policy that forensic psychiatric care should be funded by the government. Furthermore, the British participants supported the idea that forensic psychiatric services should be covered by the private sector as well; however, the Japanese participants’ opinion regarding this matter was divided.
DISCUSSION
We conducted a series of semi-structured interviews with forensic psychiatrists from the United Kingdom and Japan. The results revealed some significant differences between the opinions of psychiatrists from the two nations.
The British specialists seemed to consider risk assessment, while focusing on MDOs’ aggressive behaviors, as the key areas that should be addressed by FMH. This would imply that psychopaths and substance abusers are at the center of forensic psychiatric treatment, because they are highly relevant to violence and crimes[4]. This view also places a sense of obligation on forensic psychiatrists to maintain public safety through the risk management of MDOs.
However, the British psychiatrists seemed to be ambivalent with regard to the paradox that psychopathy as a form of mental impairment is unsuitable for the psychiatric treatment setting. Since 2001, England has been prepared for the treatment of the so-called “dangerous and severe personality disorders”[5]. However, there continues to be considerable skepticism about the efficacy and cost-effectiveness of this treatment for such disorders[6,7].
On the contrary, the Japanese psychiatrists believed that forensic psychiatric practice should involve engaging in tasks related to people who have to give psychiatric testimony and who are involved with FMH legislation. In other words, they believed that forensic practice should involve dealing only with people whose criminal responsibility is questionable[8]. Consequently, in Japan, offenders with schizophrenia are inevitably dominant in the FMH setting[9]. Since forensic psychiatrists in Japan devote most of their expertise and energy to the treatment of schizophrenic patients, they hardly deal with psychopathic patients who may be incarcerated in prison[10]. Additionally, Japanese forensic psychiatrists do not have a very strong sense of responsibility with regard to contributing to public safety.
This, however, does not imply that risk assessment is ignored in forensic practice in Japan. Considering the fact that approximately three percent of the inpatients of general psychiatric wards are secluded or physically restrained[11], psychiatrists in Japan frequently have to evaluate the risk of violent behaviors in psychiatric patients. However, it is doubtful that these assessments are based on structured professional judgment. In addition, masked medication may still be accepted in some contexts in Japan. By and large, it appears that Japanese psychiatrists tend to behave in a paternalistic manner with psychiatric patients.
In the United Kingdom, private hospitals are rapidly growing in the FMH sector[12]. Some private facilities deal with specialized or niche needs such as developmental disorders. In contrast, in Japan, the private sector has been dominant in providing psychiatric beds[11]. At present, the MTSA inpatient facilities are limited to the public sector. Nonetheless, further discussion is required to clarify the future role of the private sector in relation to FMH.
Forensic specialists from both countries paid attention to the prolongation of the term of hospitalization of MDOs. Similar to MSUs in the United Kingdom in terms of their capacity and human resources, Japanese inpatient facilities, in accordance with the MTSA in Japan[13], have more long-stay patients. However, this fact should be interpreted cautiously because some patients discharged from an MSU are transferred to a low secure unit, HSU, or prison. In contrast, Japanese legislation has no provision for discharged patients to be recalled to prison[10]; moreover, there are no facilities equivalent to HSUs in Japan.
In conclusion, this preliminary study revealed some substantial differences between the United Kingdom and Japan with regard to FMH systems as well as significant differences between the views of British and Japanese specialists in this academic area. Therefore, great caution should be exercised when analyzing evidence in different countries.
Additionally, to improve the management of MDOs, there are points that should be taken from both Japan and the United Kingdom. In Japan, the task of making structured clinical judgments for risk assessment and management should be shared broadly among psychiatric practitioners. In the United Kingdom, a consensus needs to be reached with regard to the dispute surrounding the treatability of personality disorders and psychopathy. Furthermore, in both countries, a more detailed dialogue between general psychiatrists and forensic psychiatrists is required in order to shed light on what exactly FMH practice should entail.
COMMENTS
Background
Forensic mental health is one of the focused regions in psychiatry. Japan has established a newly forensic mental health system since a decade ago. However, there are potentially several differences in the perspective of forensic mental health among countries, considering the various histories of each country.
Research frontiers
Treatment of psychopaths is a hot topic in forensic psychiatry. In many countries, several attempts have done to reduce the future risk of recidivism of psychopathic persons. But most of them were in failure. From the medical economic point of view, some countries are going to abandon the treatment of psychopaths.
Innovations and breakthroughs
This mini-study revealed the difference of ideas and perspectives toward forensic mental health in the United Kingdom and Japan. Several international comparisons are conducted previously. But there are no other examples to investigate the basic thoughts regarding this region, such as the treatment of psychopaths, social responsibility of forensic psychiatrists, and medical economics of forensic mental health.
Applications
The reader will deeply understand the difference between two countries on forensic mental health. It will provide readers a widened view and sensibility about the interpretation of the contents when readers read papers mentioning the situation in other countries.
Terminology
The Medical Treatment and Supervision Act was a legislation established in Japan in 2003, enforced in 2005, for improved care and treatment for offenders with mental disorders.
Peer-review
This is an interesting paper, with an important contribution to understanding neurobiology.
Supported by The Ministry of Health, Labour and Welfare of Japan from a Grant-in-Aid for Scientific Research, entitled “Tagai-koui wo sita seishin-shougai-sha no shakai-fukki-katei no kokusai-hikaku to iryou-keizai-teki-bunseki (International comparison of the process of rehabilitation and medical economic analysis of mentally disordered offenders)”.
Conflict-of-interest statement: The authors declare no conflicts of interest regarding this manuscript.
Data sharing statement: There is no additional data available other than in this article.
Manuscript source: Unsolicited manuscript
Specialty type: Psychiatry
Country of origin: Japan
Peer-review report classification
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Peer-review started: July 14, 2016
First decision: September 12, 2016
Article in press: November 22, 2016
P- Reviewer: Konner M, Naumann E, Tackett JL S- Editor: Qiu S L- Editor: A E- Editor: Wu HL
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9 Shiina A Iyo M Hirata T Igarashi Y Audit study of the new hospitalization for assessment scheme for forensic mental health in Japan World J Psychiatry 2015 5 234 242 26110125
10 Fujii C Fukuda Y Ando K Kikuchi A Okada T Development of forensic mental health services in Japan: working towards the reintegration of offenders with mental disorders Int J Ment Health Syst 2014 8 21 24932212
11 Ministry of Health, Labour and Welfare The data of mental health and welfare in Japan, 2012 Available from: http//www.ncnp.go.jp/nimh/keikaku/vision/630data.html
12 Hatfield B Ryan T Simpson V Sharma I Independent sector mental health care: a 1-day census of private and voluntary sector placements in seven Strategic Health Authority areas in England Health Soc Care Community 2007 15 407 416 17685986
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JFMS Open RepJFMS Open RepJORspjorJFMS open reports2055-1169SAGE Publications Sage UK: London, England 10.1177/205511691561381610.1177_2055116915613816Case ReportGlenoidectomy for treatment of a comminuted scapular fracture in a
cat Preston Timothy J Hosgood Giselle School of Veterinary and Life Sciences, College of
Veterinary Medicine, Murdoch University, Murdoch, Western Australia,
AustraliaGiselle Hosgood BVSc (Hons), MS, PhD, School
of Veterinary and Life Sciences, College of Veterinary Medicine, Murdoch
University, 90 South Street, Murdoch, Western Australia, 6150, Australia Email:
g.hosgood@murdoch.edu.au01 12 2015 Jul-Dec 2015 1 2 205511691561381618 9 2015 © The Author(s) 20152015SAGE Publications Ltd, International Society
of Feline Medicine and American Association of Feline Practitioners, unless
otherwise noted. Manuscript content on this site is licensed under Creative
Commons Licenses.This article is distributed under the terms of the Creative Commons
Attribution-NonCommercial 3.0 License (http://www.creativecommons.org/licenses/by-nc/3.0/) which
permits non-commercial use, reproduction and distribution of the work
without further permission provided the original work is attributed as
specified on the SAGE and Open Access page (https://us.sagepub.com/en-us/nam/open-access-at-sage).Case summary
This case report describes the surgical technique used and clinical outcome
of a 15-year-old neutered female cat that had a comminuted fracture of the
right glenoid and scapular neck secondary to a gunshot injury that was
treated with glenoidectomy.
Relevance and novel information
Good clinical outcomes are possible with removal of the glenoid for treatment
of comminuted fractures of the scapulohumeral joint. Glenoidectomy is a
viable alternative to amputation in cats with normal neurovascular supply to
the affected limb. Persistent functional, pain-free lameness, muscle
hypertrophy and changes in shoulder range of motion are to be expected.
cover-dateJuly-December 2015
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Introduction
Partial and complete scapulectomy are salvage procedures described in cats and dogs
with variable clinical outcomes.1–4 The reported indications for
complete or partial excision of the scapula are fracture of the glenoid,1 chronic medial glenohumeral luxation5 or, more frequently, scapular neoplasia.2–4 This report describes a
15-year-old neutered female domestic shorthair cat with a comminuted fracture of the
right glenoid and scapular neck secondary to a gunshot injury, which was treated
with glenoidectomy with preservation of the humeral head. Lameness in the right
forelimb was 3/5, 4/5 and 1/5 preoperatively, 24 h postoperatively and 6 months
postoperatively, respectively.
Case description
A 15-year-old neutered female domestic shorthair cat was presented to the primary
care veterinarian for acute onset of right forelimb lameness. The cat had been
missing for the previous 24 h and was normally an indoor/outdoor cat with free
access to the owner’s residence. Prior to this presentation, the cat was reportedly
healthy.
On presentation to the primary care veterinarian, the cat had a toe-touching to
non-weight bearing right forelimb lameness and a scab of dried blood located cranial
to the point of the right shoulder. Manipulation of the right shoulder elicited pain
and crepitus. Neurological function of the right forelimb was considered normal. The
scabbed region over the cranial aspect of the point of the right shoulder was
clipped, and a small puncture wound approximately 5 mm in diameter was noted.
Complete blood count revealed a normocytic, normochromic, mildly regenerative
anaemia (haematocrit 11.5, reference interval [RI] 30–45%). The leukogram was
normal. Serum biochemistry abnormalities included hypoproteinaemia (51 g/l; RI 57–89
g/l), hypoalbuminaemia (17 g/l; RI 23–39 g/l), decreased alkaline phosphatase enzyme
activity (13 U/l; RI 14–111 U/l) and decreased amylase enzyme activity (440 U/l; RI
500–1500 U/l). Blood electrolyte concentrations were within the normal RIs. Given
the forelimb lameness, puncture wound and marked anaemia, hypoproteinaemia and
fracture of the forelimb, anaemia secondary to haemorrhage was considered most
likely.
The cat was sedated with butorphanol (0.2 mg/kg) and midazolam (0.2 mg/kg)
intramuscularly prior to establishing intravenous (IV) access. The cat was intubated
and general anaesthesia was maintained with isoflurane in oxygen while radiographs
were taken.
Referral radiographs revealed a severely comminuted fracture of the scapular neck and
glenoid with lateral displacement (Figure 1). No fractures of the humeral head were identified. There were
fragmented metallic opacities lodged within the fractured segments of the right
scapula, which extended medially and dorsally in a linear trajectory. The largest,
most irregular metallic fragment was observed ipsilateral and adjacent to the
twelfth and thirteenth thoracic (T12 and T13, respectively) vertebrae. There was
marked increase in soft tissue opacity within the right axilla and subscapular space
with mild subcutaneous emphysema cranial to the right shoulder. The intrathoracic
structures were normal. Radiographic changes observed supported the source of the
lameness and anaemia to a single bullet that had penetrated the skin ventral to the
right mandibular ramus, tracked through the subcutaneous tissue, fractured the
scapular neck and glenoid, and subsequently fragmented within the axilla without
penetrating the thorax.
Figure 1 (a) Right mediolateral and (b) dorsoventral referral radiographic views of
the scapula and thorax. Note the comminuted fracture of the right distal
scapula, medial displacement of the humerus, axillary subcutaneous emphysema
with associated increase in soft tissue opacification and bullet
fragmentation extending from the shoulder to just lateral to the T12–T13
intervertebral space
General physical examination performed at the time of admission was similar to that
reported by the primary care veterinarian earlier that day. The cat was ambulatory
with toe-touching to non-weight-bearing lameness in the right forelimb (see video 1 in Supple-mentary
material). Neurological examination of the right thoracic limb was normal.
Withdrawal reflexes, proprioception and pain sensation was present in all other
limbs. Cranial nerve examination was also normal.
The packed cell volume (PCV)/total protein (TP) was 18 l/l and 66 g/l, respectively,
which was improved compared with the results 8 h previously. Given the anaemia and
inadequate analgesia, further in-hospital supportive care with packed red blood cell
transfusion if the PCV continued to decline and analgesia was planned. IV
crystalloid fluids and methadone (0.3 mg/kg IM; Troy Laboratories) were given
overnight, and a transdermal fentanyl patch (12 μg/h; Janssen-Cilag) was applied.
The PCV/TP were monitored and remained stable, so transfusion was not performed. The
cat was discharged for the weekend the next day with re-presentation scheduled for
the start of the following week.
Computed tomography (CT) with and without IV contrast (450 mg/kg iohexol 300; GE
Healthcare) under general anaesthesia was performed 3 days after initial referral to
better characterise the scapular fracture, axillary vasculature and thorax. The
preanaesthetic PCV/TP was improved at 26 l/l and 78 g/l, respectively. The CT
revealed multiple metallic attenuating fragments and gas-attenuating pockets
consistent with a bullet track within the right subcutaneous tissues, muscles and
scapula on the right forelimb and thoracic wall (Figure 2). There was a severely comminuted
fracture of the right distal scapula (Figure 3), with fragmentation of the glenoid
and adjacent increased soft tissue attenuation without iohexol extravastion,
suggesting fluid accumulation consistent with prior haemorrhage. The humeral head
was luxated and displaced proximomedially relative to the glenoid. There were
multiple metal fragments lodged within the bone and adjacent tissues along the
articular processes from T11 to T13, with the largest fragment lodged at the right
of the T13 spinous process and articular facet (Figure 2). The thoracic cavity was otherwise
within normal limits. There was no evidence of thrombosis or vascular compromise to
the axillary vessels in the right brachial plexus after IV contrast
administration.
Figure 2 Preoperative dorsal three-dimensional reconstruction of the cranial half of
the cat. Light purple-coloured irregularities to the right represent bullet
fragments
Figure 3 Three-dimensional reconstruction of the right glenohumeral joint. (a)
Lateral, (b) caudocranial and (c) medial views. Note the comminuted fracture
of the distal right scapula, medial displacement of the humerus and bullet
fragmentation. The humeral head is intact. There is fracture of the scapula
spine proximal to the suprahamate process
Owing to the degree of comminution, reconstruction of the glenoid, scapular neck and
the glenohumeral joint was considered unattainable. Amputation of the limb was
considered; however, this was deemed to be an extreme option given the neurological
function of the limb was normal and the humeral head and the scapula proximal to the
neck were intact. A partial distal scapulectomy (glenoidectomy) was recommended.
The following day the cat underwent glenoidectomy. The cat was premedicated with
methadone (0.3 mg/kg IM; Troy Laboratories). General anaesthesia was induced with
diazepam (0.25 mg/kg; Ceva Pharmaceuticals) and ketamine (5 mg/kg; Troy
Laboratories). Anaesthesia was maintained using isoflurane to effect. Hypotension
(mean arterial pressure <60 mmHg) determined by oscillometric non-invasive blood
pressure was observed during patient preparation. Two initial boluses of Hartmann’s
solution (10 mg/kg) failed to improve hypotension, so fentanyl (3–10 μg/kg/h;
AstraZeneca) and ketamine (10 μg/kg/min) constant rate infusion (CRI) were initiated
and maintained throughout surgery in order to reduce the end-tidal isoflurane
concentration to 1%. Despite this, hypotension only resolved (mean arterial pressue
>60 mmHg) with administration of a dopamine CRI at 5–10 μg/kg/min. Cefazolin (22
mg/kg IV; Sandoz) was administered at induction and every 90 mins throughout
surgery. The cat was positioned in left lateral recumbency and a 15 cm lateral
incision was made over the right scapula spine and then distal over the glenohumeral
joint over the proximolateral humerus. The suprascapular and axillary nerve could
not be visualised, owing to extensive soft tissue damage around the scapular neck,
acromion and glenoid. Gelpi retractors were placed into the suprapinatus and
infraspinatus fossae to retract these muscles from the scapular spine and expose the
scapular neck. The hamate and suprahamate processes of the acromion (origins of the
deltoid muscles) were attached to the scapular spine with a fine fibrous adhesion,
but had otherwise fractured as a single piece that had not displaced. The humeral
head was displaced medially and ventrally, and was manipulated back into a normal
position with bone-holding forceps.
A longitudinal fracture of the infraspinatus fossa was observed to extend from the
scapular neck to the level of the suprahamate process. Extra-articular fragments of
the glenoid and scapular neck were removed manually. The supraglenoid tubercle with
the origin of the biceps brachii and coracobrachialis was fragmented and displaced
medial to the joint, so biceps and coracobrachialis tenotomy was performed and the
supraglenoid tubercle excised. The joint capsule was incised close to the glenoid
rim, which facilitated intra-articular removal of the fragmented glenoid. The
origins of the medial and lateral glenohumeral ligament were resected at the glenoid
to help preserve as much joint capsule as possible. A transverse ostectomy was
performed with a sagittal saw across the remaining scapula approximately 1 cm
proximal to the suprahamate process. The subscapularis, teres minor, supra and
infraspinatus tendon origins remained intact. The remaining joint capsule was
sutured over the humeral head with 2-0 polydiaxonone (PDS; Ethicon).
A 2 cm × 4 cm muscle flap was created from the caudal aspect of the supraspinatus
muscle by incising it parallel to its fibres, and then rotating the pedicle caudally
between the osteotomised surface of the scapula and the joint capsule covering the
humeral head. The muscle flap was sutured in place to the scapular head of the
deltoid, the lateral head of the triceps and the joint capsule with locking loop
sutures of 2-0 PDS. The infraspinatus fascia was apposed to the supraspinatus fascia
with 2-0 PDS. The trapezius and omotransversarius muscles were then apposed to the
scapular head of the deltoid with 3-0 PDS. The subcutaneous tissue and skin were
closed. There was a smooth range of motion palpable in the right shoulder, without
abnormal abduction, rotation or crepitus. A 2 cm incision was then made along the
epaxial longissimus thoracic muscles over right side of T13. Blunt dissection was
made through the muscle to retrieve a metallic fragment of bullet; this was
submitted for culture and sensitivity, and was negative. The wound region was
lavaged prior to closure of the muscle fascia, subcutaneous tissue and skin.
Postoperative radiographs confirmed the removal of the majority of the fragmented
glenoid and scapula (Figure
4). A single sliver of bone was observed caudolateral to the humeral head
on postoperative radiographs; however, this was appreciated to be extra-articular
and embedded in soft tissues and did not pose any obstruction to shoulder range of
motion. Metallic fragments of the bullet remained in situ. Relative dorsal
translation of the humeral head was appreciated compared to the contralateral
limb.
Figure 4 Postoperative (a,b) right mediolateral and (c) dorsoventral radiographs. Note
relative dorsal displacement of the scapula and humerus in (b) during
simulated weightbearing
The cat recovered from anaesthesia with a CRI of fentanyl (1–3 μg/kg/h) without
complication and was eating and drinking several hours after surgery. Anticipating a
12 h onset of action, a transdermal buprenorphine patch (10 μg/h; Mundipharma) was
applied. Fentanyl CRI was continued until the transdermal buprenorphine patch became
active. Non-steroidal anti-inflammatories were considered but, owing to the cat’s
anaemia and hypotension under general anaesthesia, not administered. Twelve hours
after surgery there was a persistent weight-bearing right forelimb lameness at a
walk (see video 2 in
Supplementary material); however, the cat would hold the right forelimb off the
ground when not ambulating. The day after surgery the cat was discharged with a
transdermal buprenorphine patch providing a week of analgesia.
Three weeks postoperatively, the cat was re-presented for examination. The skin
incision had healed and the skin sutures were removed. A mild persistent
weight-bearing right forelimb lameness was appreciated at a walk (see video 3 in Supplementary
material). The cat was able to jump up and down from a height of several steps.
Subjectively, the right forelimb looked shorter than the contralateral forelimb, and
the scapula was more dorsally displaced. The range of motion was considered normal
and no pain or crepitus could be elicited. The triceps, biceps and deltoid muscles
of the right forelimb appeared moderately hypertrophied compared with the
contralateral limb. At this time, the supra- and infraspinatus muscles were not
atrophied. Instructions were provided to the owner to continue to restrict the cat
to small indoor areas and to prevent it from running and jumping. At the 6 month
recheck, there was marked atrophy of the supra- and infraspinatus muscles in
contrast to the 3 week recheck, suggesting that suprascapular nerve function had
been compromised. The triceps, biceps and deltoid muscles remained moderately
hypertrophied compared with the contralateral limb. As before, no pain could be
elicited with movement of the pseudoarthrosis, and range of motion was subjectively
comparable to the contralateral shoulder. The cat’s mechanical lameness at 6 months
was observed as a very slightly shortened stance phase when walking (see video 4 in Supplementary
material). The client’s impression was that the cat’s right forelimb had returned to
normal function and the cat was capable of performing all the activities it had
previously carried out without overt pain; however, it had become reluctant to jump
down from heights. Overall, the case was considered to have an excellent functional
outcome.
Discussion
This report describes the surgical technique and clinical outcome of a cat that had a
complete glenoidectomy performed to treat a comminuted fracture secondary to a
gunshot injury of the distal scapula. This case is the first known report describing
the successful use of a complete glenoidectomy with preservation of the humeral head
for management of a comminuted distal scapular fracture. Several feline and
orthopaedic textbooks describe glenoidectomy with and without humeral head excision
as a salvage procedure for diseases of the shoulder joint in cats;6–10 however, all of these sources
reference case reports in dogs.
There are reports in toy breed dogs of glenohumeral excisional arthroplasty being
performed for treatment of chronic shoulder luxation and comminuted glenoid
fractures.5,11,12 In all of these reports where glenohumeral excisional
arthroplasty was performed, the humeral head and the glenoid were both removed. In
the cat of this case report, total glenoidectomy was performed with preservation the
humeral head. The literature suggests that expected limb use after partial
scapulectomy in cats and dogs should be good to excellent when there is preservation
of neurological function, preservation of the glenoid and the glenohumeral joint,
and reconstruction of the joint’s soft tissues in lightweight animals.1,3,12,13 Despite these suggested
restrictions to ensure a favourable outcome, good-to-excellent clinical outcomes
have been reported in cats and mid-to-large breed dogs undergoing partial and total
scapulectomy,1–4,12,13 and in dogs undergoing
glenohumeral excisional arthroplasty.5,11 These reports would support
that animal size should not preclude glenoidectomy or scapulectomy as limb salvage
procedures. Furthermore, retention of the glenoid or glenohumeral collateral
ligaments may not be essential to afford a good clinical outcome.
Passive glenohumeral joint stability is primarily provided by the joint capsule and
collateral ligaments in dogs;14–17 however, the relative
contribution of these to glenohumeral stability in the cat has not been
demonstrated. The transarticular tendons (specifically the supraspinatus,
infraspinatus, biceps brachii and subscapularis, and, less so, the coracobrachialis,
teres minor and teres major) are active stabilisers of the glenohumeral joint and
require energy to contract and relax to maintain joint conformation.16,17 As described
in this case, we were able to reconstruct or maintain some of the supporting soft
tissues of the glenohumeral joint, specifically the joint capsule, supraspinatus,
infraspinatus, teres minor and subscapularis tendons, which provided some
mediolateral stability to the scapulohumeral pseudarthrosis. Furthermore, the
moderate hypertrophy of the triceps, biceps and deltoids of the affected limb noted
on examination 3 weeks postoperatively suggests that stability to the pseudarthrosis
may be actively provided by these muscles. Examination of the cat prior to discharge
and again at the 3 week recheck revealed a palpable increase in proximodistal and
flexion/extension shoulder range of motion compared with the contralateral shoulder.
No crepitus or pain was appreciated in the right shoulder at the 3 week recheck, and
limb use was considered to be good, despite a persistent mechanical lameness, which
is likely related to the effective shortening of the limb and alteration in the
shoulder range of motion. We suspect that if part of the scapula is to be retained
after glenoidectomy, then closing the joint capsule,14–17 reconstructing or maintaining
the supraspinatus, infraspinatus and subscapularis tendons, and interposing soft
tissue between cut bone ends may be important to affording a good functional outcome
in the cat.12 While the use of a muscle sling in excisional arthroplasties remains controversial,12 in this case it was deemed necessary owing to the expected pistoning during
weight bearing between the juxtaposed cut edge of the distal scapula and the humeral
head. The technique described here may not be applicable to cases with concurrent
neurological dysfunction or fracture of the humeral head.
Conclusions
A good clinical outcome is possible with removal of the glenoid for treatment of
comminuted fractures of the scapulohumeral joint. The surgical technique of
glenoidectomy is a viable alternative to amputation in cats with normal
neurovascular supply to the affected limb. A persistent functional, pain-free
lameness, muscle hypertrophy and abnormalities in shoulder range of motion are to be
expected.
Funding: The authors received no financial support for the research, authorship, and/or
publication of this article.
Conflict of interest: The authors declared no potential conflicts of interest with respect to the
research, authorship, and/or publication of this article.
Supplementary material: The following files are available:
Video 1. Preoperative video of the cat. Note the moderate weightbearing (3/5)
lameness of the right forelimb
SAGE-Journals-Accessible-Video-Player10.1177/2055116915613816.M12055116915613816_video1
Video 2: Cat 24 h postsurgery. Note the marked weightbearing (4/5) lameness of
the right forelimb. The incision is covered by a self-adhesive
dressing
SAGE-Journals-Accessible-Video-Player10.1177/2055116915613816.M22055116915613816_video2
Video 3: Cat 3 weeks postsurgery. Sutures have been removed from the incision.
Note the mild weightbearing (2/5) lameness of the right forelimb and
relative hypertrophy of the triceps and brachial muscles
SAGE-Journals-Accessible-Video-Player10.1177/2055116915613816.M32055116915613816_video3
Video 4: Cat 6 months postsurgery. Note the excellent right forelimb use and
very mild (1/5) lameness
SAGE-Journals-Accessible-Video-Player10.1177/2055116915613816.M42055116915613816_video4
==== Refs
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==== Front
Respirol Case RepRespirol Case Rep10.1002/(ISSN)2051-3380RCR2Respirology Case Reports2051-3380John Wiley & Sons, Ltd Chichester, UK 10.1002/rcr2.228RCR2228Case ReportCase ReportsA case of lung abscess successfully treated by transbronchial drainage using a guide sheath GS drainage for lung abscessH. Izumi et al.Izumi Hiroki http://orcid.org/0000-0002-9566-4859
1
Kodani Masahiro kodani@med.tottori-u.ac.jp
1
Matsumoto Shingo
1
Kawasaki Yuji
2
Igishi Tadashi
1
Shimizu Eiji
1
1 Division of Medical Oncology and Molecular Respirology, Faculty of MedicineTottori UniversityYonagoJapan2 Division of Internal MedicineTsuyama Daiichi HospitalTsuyamaJapan* Correspondence
Masahiro Kodani, Division of Medical Oncology and Molecular Respirology, Faculty of Medicine, Tottori University, 36‐1 Nishi‐machi, Yonago 683‐8504, Japan. E‐mail: kodani@med.tottori-u.ac.jp
24 3 2017 5 2017 5 3 10.1002/rcr2.v5.3e0022814 11 2016 31 1 2017 23 2 2017 © 2017 The Authors. Respirology Case Reports published by John Wiley & Sons Australia, Ltd on behalf of The Asian Pacific Society of RespirologyThis is an open access article under the terms of the Creative Commons Attribution‐NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.A 51‐year‐old man was diagnosed with colon cancer in September 2011, and a solitary pulmonary nodule was detected by computed tomography (CT) scan. We performed a transbronchial biopsy with endobronchial ultrasonography using a guide sheath (GS) and diagnosed lung metastasis of colon cancer. The patient experienced remittent fever after the biopsy in spite of intravenous antibiotic therapies. Moreover, his CT scan showed a large lung abscess at the biopsy site. We performed transbronchial drainage using a GS as salvage therapy. The bloody pus was successfully aspirated, and chest X‐ray following the procedure showed dramatic shrinkage of the abscess.
Bronchoscopydrainageendobronchial ultrasonographyguide sheathlung abscess source-schema-version-number2.0component-idrcr2228header-idrcr2228-hdr-0001cover-dateMay 2017details-of-publishers-convertorConverter:WILEY_ML3GV2_TO_NLMPMC version:5.0.9 mode:remove_FC converted:24.03.2017
Izumi , H.
,
Kodani , M.
,
Matsumoto , S.
,
Kawasaki , Y.
,
Igishi , T.
and
Shimizu , E.
(2017 ) A case of lung abscess successfully treated by transbronchial drainage using a guide sheath . Respirology Case Reports , 5 (3 ), e00228. doi: 10.1002/rcr2.228.
Associate Editor: Semra Bilaceroglu
==== Body
Introduction
Lung abscess is a subacute infection and is defined as a localized necrosis with accumulation of pus in the pulmonary parenchyma. The most common therapeutic approach to lung abscess is the long‐term administration of systemic antibiotics, but 11–21% of patients with lung abscess require surgical lung resection or percutaneous drainage 1. However, it has been reported that endobronchial drainage may be an effective treatment option for selected patients with refractory lung abscess 2. Bronchoscopy has been used to diagnose abnormal lung lesions for the past 50 years. The development of new diagnostic tools in recent years, such as endobronchial ultrasonography (EBUS) and guide sheath (GS), has substantially improved diagnostic accuracy 3. In this report, we describe a case of lung abscess which was complicated by EBUS‐GS‐transbronchial biopsy (TBB) and was successfully treated with transbronchial drainage using the GS.
Case Report
A 51‐year‐old man with no medical history was diagnosed with colon cancer in September 2011, and a solitary pulmonary nodule (left segment 6) was detected by chest X‐ray and computed tomography (CT) scan when staging the colon cancer (Fig. 1A, B). We performed a diagnostic bronchoscopy (Olympus BF‐260) and took six specimens by EBUS‐GS‐TBB from the left bronchus 6c (B6c) (Fig. 1C) under conscious sedation using midazolam. The biopsy examination used immunohistochemistry to confirm that the lung nodule was a metastasis of colon cancer. Although the patient did not have any complication or sign of infection immediately after the bronchoscopy, he developed a high fever (above 38.0°C) and cough the night after his discharge from the hospital, and he came to our hospital 6 days after the bronchoscopy. A chest X‐ray and a CT scan showed a mass shadow with niveau formation around the known nodule on which we had performed EBUS‐GS‐TBB (Fig. 1D, E). Elevations in C‐reactive protein level and white blood cell count were observed. Therefore, we diagnosed lung abscess associated with EBUS‐GS‐TBB. We started treatment with oral sitafloxacin (100 mg once per day) and intravenous injection of ampicillin–sulbactam (3.0 g once per day) as empiric therapy without evidence from bacterial culture. In spite of combined antibiotic therapy, the patient's symptoms did not improve. The patient was admitted to our hospital 9 days after the bronchoscopy, and we performed escalation therapy with intravenous injection of doripenem (0.5 g thrice a day). Although the fever lessened slightly after treatment with doripenem, the lung abscess was greatly enlarged when viewed with chest X‐ray and CT scan on the eighth hospital day. Because of poor responsiveness to antibiotic therapy, on the 11th hospital day we performed another bronchoscopy to drain the abscess and to identify the cause of infection. Bronchoscopy showed that the mucosa of left B6c orifice was reddish and swollen, which resulted in severe bronchial stenosis (Fig. 1F). Because we could not aspirate the pus with suction directly, we attempted to perform drainage using GS, which is typically used to introduce forceps and brushes into the target bronchus. The GS (Olympus SG‐201C) was inserted into the left B6c through the channel of bronchoscope (BF‐1T260) (Fig. 2A). A total of 30 mL of bloody pus was obtained when aspirating manually with a 20‐mL syringe through the GS (Fig. 2B), and a chest X‐ray just after the procedure showed a dramatic shrinkage of the abscess (Fig. 2C). After the one‐time drainage, the patient's body temperature quickly decreased to 37°C. Because penicillin‐sensitive β‐streptococcus species was detected in the aspirate culture, the patient underwent de‐escalation from doripenem to oral amoxicillin–clavulanate potassium (250 mg thrice a day). The abscess disappeared after 4 weeks of antibiotic therapy and without any invasive procedure.
Figure 1 (A) Chest X‐ray and (B) chest computed tomography (CT) demonstrated a nodule in the left lung at first visit. (C) Transbronchial biopsy (TBB) was performed from the left bronchus 6c (B6c). (D) Chest X‐ray and (E) CT showed a nodular shadow with niveau formation around the known nodule after the transbronchial biopsy. (F) Second bronchoscopy showed that the mucosa of left B6c orifice was reddish and swelling, which resulted in severe bronchial stenosis.
Figure 2 (A) An illustration of bronchoscopic drainage using guide sheath (GS). The type of flexible bronchoscope was BF‐1T260 (Olympus, Japan), and the GS was SG‐201C (Olympus, Japan) for use in scope with 2.6‐mm working channel. One‐time drainage was performed through the GS without fluoroscopy and endobronchial ultrasonography (EBUS) guidance. (B) The bloody pus obtained by the procedure. (C) Chest X‐ray just after the bronchoscopic drainage showed dramatic shrinkage of the lung abscess.
Discussion
Bronchoscopy is a common and effective method for the diagnosis of lung lesions. The most frequent complications of bronchoscopy are haemorrhage, pneumothorax, and infection. The risk of infection includes infection with pneumonia, although incidence is less than 1% 4. There have been few reports of lung abscess arising as a complication of EBUS‐GS‐TBB 5.
In this case, antibiotic therapies, including penicillin, new quinolone, and carbapenem, were administered empirically and were unsuccessful. However, the abscess dramatically reduced upon one‐time drainage using GS. This result suggests the importance of drainage in the treatment of lung abscess. As an alternative approach to percutaneous drainage or lung resection in patients refractory to antibiotic therapy, endoscopic continuous drainage has been reported to be safe and effective if there is an airway present that leads to the abscess 2.
In this case, we selected bronchoscopic drainage as a treatment method because the abscess was associated with a bronchoscopic biopsy, and the bronchus was therefore expected to have a connection to the abscess. As a result, the bronchoscopic drainage using GS contributed to the cure of the lung abscess as well as to the identification of the causative bacteria without any complication. The one‐time drainage using GS is far less invasive than surgical resection, percutaneous drainage, or continuous endoscopic drainage. We believe that bronchoscopic drainage using GS is an effective alternative strategy for the treatment of lung abscess in patients who have an airway connection to the abscess.
In summary, we report the first successful case of transbronchial drainage using GS for lung abscess complicated by EBUS‐GS‐TBB. This transbronchial drainage procedure using GS may be an effective and safe strategy in the treatment of lung abscess with airway connection in patients who are refractory to antibiotic therapy.
Disclosure Statements
No conflict of interest declared.
Appropriate written informed consent was obtained for publication of this case report and accompanying images.
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SSM Popul HealthSSM Popul HealthSSM - Population Health2352-8273Elsevier S2352-8273(16)30065-910.1016/j.ssmph.2016.09.001ArticleNeighborhood disadvantage and preterm delivery in Urban African Americans: The moderating role of religious coping Sealy-Jefferson Shawnita ssealyjeffers@vcu.edua⁎Slaughter-Acey Jaime bCaldwell Cleopatra H. cKwarteng Jamila dMisra Dawn P. ea Virginia Commonwealth University, Department of Family Medicine and Population Health, Division of Epidemiology, United Statesb Drexel University, College of Nursing and Health Professions, United Statesc University of Michigan, School of Public Health, Department of Health Behavior and Health Education, United Statesd Medical College of Wisconsin, Department of Medicine, United Statese Wayne State University, School of Medicine, Department of Family Medicine and Public Health Sciences, United States⁎ Correspondence to: Virginia Commonwealth University, P.O. Box 980212, Richmond, VA 23298, United States.Virginia Commonwealth UniversityP.O. Box 980212RichmondVA23298United States ssealyjeffers@vcu.edu09 9 2016 12 2016 09 9 2016 2 656 661 28 4 2016 16 8 2016 6 9 2016 © 2016 The Authors2016This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).Evidence suggests that neighborhood disadvantage predicts preterm delivery (PTD). However, the design of most existing studies precludes within-group analyses, which would allow the identification segments of the population at highest risk, as well as preventive factors. African Americans (AA) are disproportionately affected by PTD, are disproportionately concentrated in disadvantaged neighborhoods, and frequently use religious coping in response to chronic stressors. Our objective was to examine the association between neighborhood disadvantage and PTD, and whether religious coping moderated the associations, among postpartum AA women. Addresses from participants of the Life Influences on Fetal Environments Study (n=1387) were geocoded and linked to data from the American Community Survey. An index of neighborhood disadvantage was derived from a principal components analysis of the following variables: % below poverty, % unemployed, % receiving public assistance income, % college educated, % AA, % female-headed households, % owner occupied homes, median income, and median home value. Three domains of religious coping were assessed: organizational (church attendance), non-organizational (praying for self and asking others for prayer), and personal or subjective (experiences, perceptions, and sentiments about religion), and all were dichotomized as frequent/infrequent or satisfied/not satisfied. Preterm delivery was defined as birth before 37 completed weeks of gestation. Prevalence ratios and 95% confidence intervals were estimated with log binomial regression models. Neighborhood disadvantage did not predict PTD rates in the overall sample. However, there was evidence of moderation by asking others for prayer (P for asking for prayer X disadvantage index interaction term: 0.01). Among women who infrequently asked others for prayer, neighborhood disadvantage was positively associated with PTD rates (adjusted Prevalence ratio: 1.28, 95% Confidence Interval: 1.01, 1.63), and a null association was found for those who frequently asked others for prayer. No evidence of moderation by the other religious coping variables was present. Non-organizational religious coping may buffer against the adverse effects of neighborhood disadvantage on PTD rates, among urban AA women. Future research should examine the mechanisms of the reported relationships.
Highlights
• We identified a novel preventive factor for preterm delivery in African Americans.
• Non-organizational religious coping may buffer against neighborhood disadvantage.
• Religiosity may provide health promoting social support for African American women.
Keywords
Neighborhood contextPreterm deliveryReligious copingAfrican American
==== Body
1 Introduction
Racial disparities in preterm delivery (PTD), or birth prior to 37 completed weeks of gestation, have existed for decades, with African American (AA) women being disproportionately impacted (Branum & Schoendorf, 2002; Costa, 2004). While the leading cause of infant mortality in the United States is PTD, the etiology of PTD remains unknown (Romero, Dey, & Fisher, 2014). Social conditions have been posited as fundamental causes of health inequalities (Phelan, Link, & Tehranifar, 2010). For instance, the quality of the residential environment (or neighborhood) is patterned by racial/ethnic status and social position, (Diez Roux & Mair, 2010) such that AAs compared to Non-Hispanic whites (NHW), are more likely to reside in disadvantaged neighborhoods, including those with inadequate municipal services and health care resources, increased crime, violence, and poor housing quality (Culhane & Elo, 2005).
Much of the literature on the relationship between neighborhood context and PTD uses vital statistics data (Miranda, Messer & Kroeger, 2012; Farley 2006; Masho, Munn & Archer, 2014; O’Campo, Burke & Culhane, 2008; Janevic et al., 2010; Vinikoor-Imler, Messer, Evenson & Laraia, 2011; Ma, Liu, Hardin, Zhao & Liese, 2015; Masi, Hawkley, Piotrowski & Pickett, 2007; Wallace et al., 2013; Messer, Kaufman, Dole, Savitz & Laraia, 2006; Ncube, Enquobahrie, Albert, Herrick & Burke, 2016). Results from a recent meta-analysis, which included three studies focused on AAs, all of which used vital statistics data, suggested modest positive associations, with a stronger relationship among Whites compared to AAs (Ncube et al., 2016). However, limitations of using vital statistics data include inaccurate reporting of clinical information including gestational age, and that the data is collected for public health surveillance, rather than to answer specific clinical or population-based research questions (Schoendorf & Branum, 2006).
Studies which use primary collected data can include a more complete assessment and control for social determinants which may confound or modify the association between neighborhood context and PTD. In the most recently published study using primary collected data, Bastek and colleagues reported no significant association between neighborhood context and PTD in a cohort of 817 mostly AA women from Philadelphia (Bastek et al., 2015). Similarly, Phillips et al. examined the association between an aggregate socioeconomic measure of neighborhood quality and spontaneous PTD, using data from the Black Women's Health Study and found no significant associations (Phillips, Wise, Rich-Edwards, Stampfer, and Rosenberg, 2013).
Social exposures have complex and dynamic relationships and interactions, (Hertzman & Boyce, 2010) but only a few studies examined whether the impact of neighborhood exposures on PTD varies by social factors. Philips et al., found no evidence that the association between neighborhood quality and spontaneous PTD varied by sociodemographic or geographic variables. On the other hand, Ahern et al., using data from a case-control study of AA and Whites, reported that among AAs, the association between neighborhood characteristics and PTD was modified by individual-level socioeconomic status (Ahern, Pickett, Selvin, & Abrams, 2003). Further, our group recently published results from a study where we found evidence of effect modification of the association between subjective reports of the residential environment and PTD, by educational attainment, among AA women (Sealy-Jefferson, Giurgescu, Helmkamp, Misra, & Osypuk, 2015).
Religiosity has been conceptualized as a social determinant of health, (Idler, 2014) and includes several domains, including organizational (formal church attendance), non-organizational (private of informal activities), and personal or subjective (experiences, perceptions, and sentiments about religion) (Pargament, 1997; Chatters, Levin & Taylor, 1992; Taylor, Mattis & Chatters, 1999). Specifically, non-organizational religiosity, including prayer, reading religious materials, and soliciting support and prayers from a religious community, is a common response to health issues, chronic poverty, racism, and adverse residential environment among AAs (Dunn and Horgas, 2000; Krause, 1998). Religious coping is also more prevalent among women, (Ellison and Taylor, 1996) and praying for oneself or asking someone to ‘pray on your behalf’ is among the most utilized forms of coping with individual problems and stress, among AAs (Taylor, Chatters, & Levin, 2004). Since neighborhood disadvantage is conceptualized as a stressor, and stress during pregnancy has been established as a risk factor for adverse birth outcomes,(Dunkel Schetter, 2011) examining the associations between neighborhood stressors, religious coping, and PTD among urban AA women could help to identify subgroups of the population which are most susceptible to the influences of adverse neighborhood conditions.
As a result, our objective was to examine the associations between a composite measure of neighborhood quality and PTD, among urban AA women, and to determine whether the associations were modified by different approaches to religious coping. We tested the following hypotheses: (1) The association between neighborhood disadvantage (composite measure) and PTD is moderated by religious coping among urban AA women, and (2) the neighborhood disadvantage -PTD association is attenuated in those who utilize religious coping more frequently. Further, in exploratory analyses, we examined the same hypotheses as above, but for each neighborhood variable which comprised the composite disadvantage index, separately.
2 Methods
2.1 Study design
Details of the study design have been previously published (Sealy-Jefferson et al., 2015). In brief, the Life Influences on Fetal Environments (LIFE) study is a retrospective cohort, with enrollment occurring from 2009 to 2011 (but the current analysis uses cross-sectional data). The primary objective of the study was to determine how racism is associated with PTD (Slaughter-Acey, Sealy-Jefferson, & Helmkamp, 2016). Self-identified African American women (≥18 years old) who delivered a singleton infant, were recruited at a hospital in Oakland County, Michigan. Women were excluded from the study if they: (1) did not speak English or (2) had intellectual disabilities, serious cognitive deficits, or significant mental illness, on the basis of history or any prior records. In-person interviews were conducted during women's postpartum hospital stay and medical history was abstracted from medical records. The final study sample included 1411 women which represented 71% of the women approached for study participation. This study was approved by institutional review boards at St. John Providence Health System, University of Michigan and Wayne State University. All study participants gave written informed consent.
2.2 Outcome ascertainment
PTD was defined as delivery prior to 37 completed weeks of gestation. Gestational age was determined using data obtained from the medical record. We employed a hierarchical algorithm, with priority given to the provider's estimate of gestational age based on early ultrasound (between 6-20 weeks gestation) as this is considered the most valid measure of gestational age (Kalish, Thaler & Chasen, 2004; Verburg, Steegers & De Ridder, 2008). Early ultrasound estimates of gestational age (n=692) were compared to other estimates including date of last menstrual period. In the case of an inconsistency, the estimate based on the early ultrasound was used, unless it was implausible (<22 weeks or >44 weeks gestation) (Talge, Mudd, Sikorskii, & Basso, 2014). When a gestational age estimate based on an early ultrasound was not available, the last menstrual period was used (n=465). In rare cases where both the early ultrasound and last menstrual period estimates of gestational age were missing or implausible, we used the late ultrasound estimate (after 20 weeks gestation) (n=169) or the provider's estimate of gestation at birth (n=62), or that from the medical record at birth, if all else was missing (n=22).
2.3 Exposure ascertainment
Current addresses were self-reported (n=1181), and if incomplete or missing (n=230), were ascertained from the medical record, and were geocoded. Twenty four addresses could not be matched, and were omitted from the analysis; the final analytic sample included 1387 women. The latitude and longitude of each matched address was spatially linked to 5-year block group estimates (2007–2011) from the American Community survey (ACS), using ArcGIS 10.2. The following 9 variables from the ACS were used to characterize the quality of the residential environment: % below poverty, % unemployed, % receiving public assistance income, % African American, % female-headed households, % college graduate, % owner-occupied homes, median income, and median home value. Principal components analysis was used to generate a summary score representing objective neighborhood disadvantage, which was a linear composite of the nine optimally weighted ACS variables (higher score=more disadvantage) (Messer et al., 2006, Messer and Kaufman, 2006). Factor loadings were highest for median income (84%), and lowest for % of owner occupied homes (42%) (data not shown).
2.4 Effect modifiers
Given that religiosity is a multidimensional construct, we tested whether various measures of religious coping modified the association between neighborhood disadvantage and PTD. Current religious coping was self-reported and categorized into organizational, non-organizational, and subjective domains (Jackson, Torres & Caldwell, 2004; Jackson, Neighbors, Nesse, Trierweiler & Torres, 2004). Religious service attendance (organizational domain) was ascertained with “How often do you attend religious services?”, answer choices were: everyday, at least once a week, a few times a month, a few times a year, less than once a year, and never. Non-organizational religious coping was assessed with two questions: (1) “How often do you pray”, and (2) “How often do you ask someone to pray for you”, with responses on a Likert scale (very often, fairly often, not too often, or never). For the subjective religiosity domain, participants were asked, “How satisfied are you with the quality of the relationships you have with the people in your church or place of worship”, and answer choices ranged from 1 (completely satisfied) to 7 (completely dissatisfied).
2.5 Statistical analysis
Cut-points for all covariates in our analysis were based on the distributions in the sample. Univariate and bivariate statistics were used to describe the data, with Wilcoxon rank sum and chi-square tests used to assess group differences for continuous and categorical variables, respectively. Pearson correlations were estimated for individual ACS neighborhood and religious coping variables. In order to interpret the results as the quality of the residential environment among women in the 75th versus the 25th percentile of the distribution of each neighborhood variable, we re-scaled the continuous neighborhood variables by their interquartile range. We considered using hierarchical models to estimate the multilevel association between neighborhood disadvantage and PTD, however there was insufficient variability in PTD rates, by block group in the sample (intra-class correlation coefficient: 0.96%). As a result, we estimated prevalence ratios (PRs) and their associated 95% confidence intervals, using log binomial regression models, to examine the relationship between PTD and each individual ACS neighborhood variable (separately) and with the neighborhood disadvantage index. Models were run unadjusted and adjusted for the following self-reported, individual-level variables, which were identified from the literature as possible confounders: age (<35, ≥35 years), income (median split: <$35,000, ≥$35,000/year), maternal relationship status (dichotomized as married or cohabitating with the father of the baby, versus not married or cohabitating with the father of the baby), and educational attainment (≤12, >12 years). Our education variable included the highest level of education and considered several sources, including number of completed years, year of high school graduation, alternative education (e.g. general equivalency, career academies, and technical training), as well as traditional brick and mortar and online college attendance, and college graduation. We categorized the education variable as ≤12 and >12 years based on the heterogeneity in type of education among those who reported >12 years. Moderation by the 3 domains of religious coping was assessed with interaction terms between individual indicators and a composite measure of neighborhood disadvantage (each modeled separately) and each religious coping variable. Non-organizational religious coping variables were categorized as frequently (very often) and infrequently (including fairly often, not too often, and never). Organizational religious coping was dichotomized at the median as frequently and infrequently. Subjective religiosity was also dichotomized at the median and categorized as satisfied versus not satisfied. We present models stratified by religious coping, if warranted. All variables were assessed for missing data, and list-wise deletion was employed. The proportion of missingness ranged from 0% to 11% (n=152 missing for income). Due to the exploratory and hypothesis generating nature of this work, we did not adjust for multiple comparisons. Two-sided p<0.05 (for interaction terms), and confidence intervals which did not overlap 1 (for log binomial models) were considered significant. Analyses were conducted with SAS, version 9.4 for Windows (SAS Institute, Inc., Cary, North Carolina).
3 Results
Table 1 displays demographic and religious coping characteristics of the study population. The mean age of the sample was 27 years, over 50% were married to or cohabitating with the father of the baby, and more than 70% had a more than 12 years of education. More than half of the women resided in their current neighborhood for ≤2 years. Roughly 50% of study participants reported frequent religious service attendance and a similar number reported satisfaction with the quality of the relationships they had with people from their church or place of worship. Approximately 37% asked others to pray for them frequently, while 68% reported praying for themselves frequently. There were weak correlations between the religious coping variables with the highest between religious service attendance and satisfaction with the quality of the relationships with people in church or place of worship (0.41). Similarly, for individual neighborhood quality indicators, weak to moderate correlations were observed, with the highest between median income and median home values (0.68) (data not shown).Table 1 Demographic characteristics of study participants and results of bivariate log-binomial models; Life Influences on Fetal Environments Study (n=1387) 2009-2011.
Table 1 Missing N (%) Term Delivery (n=1160) N (%) Preterm (n=226) N (%) PR 95% CI
Age 0 (0)
18-19 102 (8.79) 14 (6.19) 0.83 0.48, 1.45
20-24 354 (30.52) 73 (32.30) 1.18 0.85, 1.63
25-29 313 (26.98) 53 (23.45) Referent
30-34 223 (19.22) 43 (19.03) 1.12 0.77, 1.62
35+ 168 (14.48) 43 (19.03) 1.41 1.00, 2.03
Relationship status 11 (0.79)
Not married or cohabitating with FOB 543(47.18) 102(45.54) 0.94 0.74, 1.20
Married to or cohabitating with FOB 608 (52.41) 122 (53.98) Referent
Education (years) 5 (0.36)
≤12 333 (28.71) 62 (27.43) Referent
>12 827 (71.29) 164 (72.57) 1.05 0.81, 1.38
Income 152 (10.96)
Under $35,000 530 (45.69) 123(54.42) 1.29 1.00, 1.66
$35,000 or more 497 (42.84) 85 (37.61) Referent
Time in current neighborhood 22 (1.59)
≤ 24 months 641 (55.26) 123 (54.42) Referent
>24 months 501 (43.19) 99 (43.81) 1.03 0.80, 1.31
Religious service attendance 13 (0.94)
Frequently 639 (55.09) 121 (53.54) Referent
Infrequently 511 (44.05) 102 (45.13) 1.05 0.82, 1.33
⁎Satisfaction with quality of relationships with people from religious services 197 (14.20)
Satisfied 573 (49.40) 119 (52.65) Referent
Not satisfied 423 (36.47) 74 (32.74) 0.87 0.66, 1.13
Ask others to pray for you 116 (8.36)
Frequently 376 (35.44) 90 (43.06) Referent
Infrequently 685 (64.56) 119 (56.94) 1.30 1.02, 1.67
Pray for yourself 93 (0.94)
Frequently 730 (67.66) 151 (70.56) Referent
Infrequently or never 349 (32.34) 63 (29.44) 1.12 0.86, 1.47
PR: bivariate prevalence ratio; 95% CI: confidence interval; n: number; FOB: father of the baby; not married includes divorced, separated, widowed, in a relationship with the FOB and non-FOB partner; married includes women who reported being married to or cohabitating with the father of the baby; ⁎only people who reported attending religious services answered this question
Table 2 shows the mean and standard deviation of the composite neighborhood disadvantage index and the individual ACS variables, as well as results of log binomial regression analysis of PTD rates among women in the 75th versus the 25th percentiles of individual indicators of neighborhood quality, and our disadvantage index. There was evidence of moderation of the association between neighborhood disadvantage (composite and some individual measures) and PTD by both praying for oneself and asking others for prayer (Table 2). Specifically, asking others for prayer modified associations between PTD rates and the following neighborhood quality measures (p for interaction terms): % African American (p=0.02), % below poverty (p =0.02), % female- headed households (p=0.003), median income (p=0.002), % college graduate (p=0.004), median home value (p<0.001), and the index of neighborhood disadvantage (p=0.005). Evidence of moderation by praying for oneself was present for associations between PTD and % unemployed (p=0.02), % below poverty (p=0.02), median income (p=0.04), and median home value (p=0.02).Table 2 Log-binomial regression results for associations comparing the 75th versus the 25th percentiles of individual neighborhood quality indicators and an index of neighborhood disadvantage and preterm delivery, and interaction effects between religious coping and neighborhood characteristics; Life Influences on Fetal Environments Study (n=1387), 2009-2011.
Table 2Neighborhood Characteristic Mean (SD) Unadjusted Adjusted⁎ Asking others for prayer Praying for self Church attendance Satisfaction with relationships with people from church
X X X X
neighborhood characteristic neighborhood characteristic neighborhood characteristic neighborhood characteristic
PR 95%CI PR 95% CI
P value P value P value P value
Disadvantage Index 0 (1) 1.08 0.92, 1.28 1.03 0.86, 1.23 0.005 0.12 0.94 0.96
Individual Variables
% welfare 5.96 (6.74) 1.05 0.93, 1.18 1.04 0.92, 1.19 0.80 0.67 0.99 0.92
%unemployed 11.04 (7.16) 1.02 0.89, 1.17 1.00 0.87, 1.15 0.10 0.02 0.78 0.94
% African American 69.91 (32.18) 1.01 0.84, 1.21 0.97 0.80, 1.18 0.02 0.62 0.72 0.90
% below poverty 12.25 (11.20) 1.09 0.95, 1.24 1.08 0.94, 1.25 0.02 0.02 0.82 0.08
% female headed household 25.21 (13.43) 1.20 1.03, 1.39 1.15 0.98, 1.36 0.003 0.38 0.32 0.44
% owner occupied homes 58.56 (27.58) 0.99 0.83, 1.18 1.00 0.83, 1.20 0.56 0.97 0.45 0.91
median income $43,068.13 ($22,197.00) 0.98 0.81, 1.08 0.98 0.84, 1.14 0.002 0.04 0.78 0.74
% college graduate 29.66 (16.75) 1.01 0.85, 1.09 1.09 0.91, 1.31 0.004 0.11 0.95 0.66
Median home value $102,933.60 ($63,117.32) 0.99 0.88, 1.11 1.03 0.92, 1.15 <0.001 0.02 0.70 0.78
SD: standard deviation
⁎ models adjusted for age, relationship status and income; PR: prevalence ratio; 95% CI: confidence interval; p: p-value
Given the evidence of interactions between non-organizational religious coping (asking others for prayer, and praying for self) with both individual and composite neighborhood quality indicators, we present the stratified parameter estimates (Table 3, Table 4, respectively). Among women who asked for prayer infrequently, those who lived in neighborhoods with high disadvantage (composite measure) had higher PTD rates than women who lived in neighborhoods with low disadvantage (adjusted PR (aPR)): 1.28, 95% CI: 1.01, 1.62) (Table 3). When we examined associations between PTD and individual neighborhood quality measures separately, stratified by asking others for prayer, a complex set of results emerged. Among women who asked for prayer frequently, PTD rates were higher among those who lived in neighborhoods with high median income (aPR: 1.23, 95% CI: 1.01, 1.50), % college graduates (aPR: 1.37, 95% CI: 1.06, 1.77) and median home values (aPR: 1.35, 95% CI: 1.17, 1.56), compared to women who lived in neighborhoods with low median income, % college graduates and median home values. In women who asked for prayer infrequently, we observed significant adjusted associations between PTD and % below poverty, % female headed households, median income, and median home values that were in the expected direction.Table 3 Log binomial models, stratified by asking others for prayer, for associations between individual neighborhood quality indicators and an index of neighborhood disadvantage, and preterm delivery among African American women; Life Influences on Fetal Environments Study (n=1271), 2009–2011.
Table 3 Frequently (n=466) Infrequently (n=805)
Neighborhood variables Unadjusted Adjusted⁎ Unadjusted Adjusted*
PR 95% CI PR 95% CI PR 95% CI PR 95% CI
Disadvantage index 0.86 0.67, 1.12 0.79 0.60, 1.05 1.31 1.04, 1.64 1.28 1.01, 1.62
Individual ACS variables
% African American 0.84 0.65, 1.10 0.77 0.59, 1.01 1.15 0.88, 1.49 1.18 0.88, 1.57
% below poverty 0.90 0.71, 1.14 0.88 0.68, 1.13 1.21 1.03, 1.43 1.24 1.05, 1.46
% female headed households 0.95 0.74, 1.29 0.88 0.67, 1.15 1.46 1.19, 1.78 1.46 1.18, 1.80
Median income 1.21 1.00, 1.45 1.23 1.01, 1.50 0.74 0.59, 0.93 0.77 0.61, 0.98
% college graduate 1.33 1.04, 1.70 1.37 1.06, 1.77 0.80 0.63, 1.02 0.86 0.66, 1.12
Median home value 1.29 1.13, 1.47 1.35 1.17, 1.56 0.76 0.63, 0.92 0.77 0.63, 0.94
⁎ models adjusted for age, relationship status, educational attainment, and income; ACS: American community survey; PR: prevalence ratio; 95% CI: confidence interval; p: p-value
Table 4 Results of log binomial models, stratified by praying for self, for associations between individual neighborhood quality indicators and preterm delivery among African American women; Life Influences on Fetal Environments Study (n=1294), 2009–2011.
Table 4 Frequently (n=881) Infrequently (n=413)
Neighborhood variables Unadjusted Adjusted⁎ Unadjusted Adjusted*
PR 95% CI PR 95% CI PR 95% CI PR 95% CI
% Unemployed 0.97 0.82, 1.14 0.94 0.79, 1.12 1.29 1.02, 1.63 1.31 1.03, 1.68
% below poverty 0.99 0.83, 1.18 0.98 0.82, 1.18 1.30 1.06, 1.60 1.34 1.10, 1.64
Median home value 1.05 0.95, 1.16 1.08 0.98, 1.19 0.74 0.58, 0.96 0.77 0.58, 1.01
Median income 1.02 0.87, 1.19 1.05 0.88, 1.25 0.68 0.48, 0.94 0.72 0.50, 1.03
⁎ models adjusted for age, relationship status, educational attainment, and income; PR: prevalence ratio; 95% CI: confidence interval; p: p-value
The PTD rates among those women who reported praying for themselves infrequently appeared to be affected by features of neighborhood environment (Table 4). Specifically, PTD rates among women who reported praying for themselves infrequently, were positively associated with neighborhood % unemployed (aPR: 1.31, 95% CI: 1.03, 1.68) and % below poverty (aPR: 1.34, 95% CI: 1.10, 1.64).
4 Discussion
Our study is the first to examine the moderating role of religious coping on the impact of neighborhood disadvantage on PTD rates, among African American women. Our primary finding was that non-organizational forms of religious coping may interact with neighborhood disadvantage to impact PTD rates, among urban AA women. Specifically, we found evidence to support our hypothesis that religious coping may buffer AA women against the influences on PTD of living in a neighborhood with high disadvantage. We also found evidence suggesting that among women who reported frequently asking others to pray for them, several positive neighborhood characteristics were surprisingly associated with increased PTD rates.
Religious social support has been associated with several health benefits, and may provide recipients with increased self-confidence, knowledge, camaraderie, and valuable assistance, which buffers against the effects of stress (Cohen & Stress, 1985). It is unclear why we observed positive associations between neighborhood % college graduate, median income, and home values and PTD, only among women who ask for prayer frequently. It is possible that in these neighborhoods, other social factors (including police brutality, violent and property crime, etc.) were present, which could increase PTD rates by increasing levels of maternal stress, even despite increased neighborhood socioeconomic status and educational level of residents. Increased levels of maternal stress can lead to rising levels of the corticotropin-releasing hormone that triggers a sequence of events that result in PTD (Wadhwa, 2001). Further, the stressful impact of these exposures may overwhelm the potential ‘protective’ effects of these positive neighborhood features on PTD rates, and could conceivably cause residents to solicit more frequent prayers from others on their behalf. More research on this specific phenomenon is warranted, especially given the evidence that gains from educational achievement are not equally manifested in AAs and Whites. In particular, systematic social observations and/or linking crime data to resident perception and demographic data could increase our understanding of these processes.
Our study has several strengths. First, we are the first to examine and identify interactive associations between neighborhood quality and non-organizational religious coping and how they may act together to impact PTD rates, among urban AA women. This work adds to the literature on neighborhood effects, in that we examine within-group variations of the impact of neighborhood disadvantage on PTD among a high risk group. Our study population is understudied, and is at high risk for PTD, and we identify a novel preventive factor in this group. In this study, we present results from a composite measure as well as individual indicators of neighborhood disadvantage, which will be useful for future hypothesis generation, as to which specific features of the residential environment may increase risk of PTD, as well as testing potential mechanisms.
In interpreting the results from our study, the following limitations should be considered. There is a potential for measurement error and residual confounding, especially given our ascertainment of neighborhood characteristics from the ACS, data which may be unequal proxies of adverse neighborhood quality. Next, 11% of our sample had missing data on individual income, and as a result, bias in our parameter estimates cannot be ruled out. This study was cross-sectional in nature, and as such, we cannot make causal inferences, or rule out the possibility that women who had a PTD may have differentially reported their religious coping habits, compared to women who had a term delivery. Since theories suggest that religious socialization occurs across the life-course, (Wielhouwer, 2004) future longitudinal studies should examine whether change in religiosity over time moderates the associations presented here. Our study sample was recruited from one hospital in Metropolitan Detroit, Michigan. However, this site was chosen based on several reasons, including its wide catchment area, the heterogeneity of women receiving medical care (64 municipalities from 3 counties), and the large number of births per year.
In summary, neighborhood quality, as assessed by administratively defined individual and composite indicators, may not impact PTD rates equally among all women, and may be moderated by non-organizational religiosity. Future studies should examine the ways in which religious coping may be a relevant form of social support for women across the life-course, and how this support may buffer women from exposures to the complex social determinants of adverse birth outcomes.
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Vinikoor-Imler L.C. Messer L.C. Evenson K.R. Laraia B.A. Neighborhood conditions are associated with maternal health behaviors and pregnancy outcomes Social Science & Medicine 73 9 2011 1302 1311 21920650
Wadhwa P.D. Stress and preterm birth: neuroendocrine, immune/inflammatory, and vascular mechanisms Maternal and Child Health Journal 5 2 2001 119 125 11573837
Wallace M. Harville E. Theall K. Webber L. Chen W. Berenson G. Neighborhood poverty, allostatic load, and birth outcomes in African American and white women: findings from the Bogalusa Heart Study Health Place 24 2013 260 266 24184350
Wielhouwer P.W. The impact of church activities and socialization on African-American religious commitment* Social Science Quarterly 85 3 2004 767 792
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Health Serv Res Manag EpidemiolHealth Serv Res Manag EpidemiolHMEsphmeHealth services research and managerial epidemiology2333-3928SAGE Publications Sage CA: Los Angeles, CA 10.1177/233339281662960010.1177_2333392816629600Original ResearchDevelopment of an Inventory for Health-Care Office Staff to Self-Assess Their Patient-Centered Cultural Sensitivity Tucker Carolyn M. 1Wall Whitney A. 2Wippold Guillermo 1Roncoroni Julia 1Marsiske Michael M. 1Linn Gabriel S. 11 Department of Psychology, University of Florida, Gainesville, FL, USA2 Department of Psychology, Fayetteville State University, Fayetteville, NC, USAWhitney A. Wall, Fayetteville State University, 1200 Murchison Rd, Fayetteville NC, FL 28301, USA. Email: wwall1@uncfsu.edu12 2 2016 Jan-Dec 2016 3 23333928166296009 12 2015 9 12 2015 © The Author(s) 20162016SAGE PublicationsThis article is distributed under the terms of the Creative Commons Attribution-NonCommercial 3.0 License (http://www.creativecommons.org/licenses/by-nc/3.0/) which permits non-commercial use, reproduction and distribution of the work without further permission provided the original work is attributed as specified on the SAGE and Open Access page (https://us.sagepub.com/en-us/nam/open-access-at-sage).Background:
Patient-centered culturally sensitive health care (PC-CSHC) is a best practice approach for improving health-care delivery to culturally diverse populations and reducing health disparities. Despite patients’ report that cultural sensitivity by health-care office staff is an important aspect of PC-CSHC, the majority of available research on PC-CSHC focuses exclusively on health-care providers. This may be due in part to the paucity of instruments available to assess the cultural sensitivity of health-care office staff. The objective of the present study is to determine the psychometric properties of the Tucker-Culturally Sensitive Health Care Office Staff Inventory-Self-Assessment Form (T-CSHCOSI-SAF). This instrument is designed to enable health-care office staff to self-assess their level of agreement that they display behaviors and attitudes that culturally diverse patients have identified as office staff cultural sensitivity indicators.
Methods:
A sample of 510 health-care office staff were recruited at 67 health-care sites across the United States. These health-care office staff anonymously completed the T-CSHCOSI-SAF and a demographic data questionnaire.
Results and Level of Evidence:
Confirmatory factor analyses of the T-CSHCOSI-SAF revealed that this inventory has 2 factors with high internal consistency reliability (Cronbach’s αs= .916 and .912).
Conclusion and Implications:
The T-CSHCOSI-SAF is a useful inventory for health-care office staff to assess their own level of patient-centered cultural sensitivity. Such self-assessment data can be used in the development and implementation of trainings to promote patient-centered cultural sensitivity of health-care office staff and to help draw the attention of these staff to displaying patient-centered cultural sensitivity.
patient-centerednesspractice managementprimary carecost-effectivenessquality improvementcover-dateJanuary-December 2016
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Introduction
Patient-centered culturally sensitive health care (PC-CSHC) has been recognized as a best practice approach for improving health-care delivery to culturally diverse populations and reducing health disparities.1–3 The PC-CSHC has been defined by culturally diverse patients as health care that enables these patients to feel comfortable with, trusting of, and respected by their health-care providers, health-care office staff, and the health-care clinic environment and policies.4
Despite patients’ report that culturally sensitive health care is multifaceted, the majority of available research pertaining to PC-CSHC focuses exclusively on health-care providers.4–6 Additionally, despite evidence regarding patients’ perception of the important role of health-care office staff in the health-care delivery system and in patients’ experience of PC-CSHC, there is limited research on the patient-centered cultural sensitivity of health-care office staff.7–10 This may be due in part to the paucity of inventories available to measure the patient-centered cultural sensitivity of health-care office staff.3 Tucker and colleagues introduced and validated the only known inventory designed for culturally diverse patients to evaluate the patient-centered cultural sensitivity of their health-care office staff.3 This inventory is the Tucker-Culturally Sensitive Health Care Office Staff Inventory-Patient Form (T-CSHCOSI-PF).3
While the T-CSHCOSI-PF provides a means for patients to assess the cultural sensitivity of their health-care office staff, there are no known inventories designed for health-care office staff to self-assess their level of patient-centered cultural sensitivity. Self-assessment inventories are commonly used and valued in health-care research and practice and have been recommended for use as a tool to improve health-care quality and increase cultural sensitivity and competence.11,12 Self-assessment inventories also encourage self-awareness and self-reflection—hallmarks of multicultural training/competence and improved clinical care.12,13
The purpose of the present study is to develop the final version of the Tucker-Culturally Sensitive Health Care Office Staff Inventory—Self Assessment Form (T-CSHCOSI-SAF). The T-CSHCOSI-SAF is a revised version of the T-CSHCOSI-PF.3 The difference between the 2 assessment inventories is that the T-CSHCOSI-PF is used by patients to rate the level of patient-centered cultural sensitivity of their health-care office staff, whereas the T-CSHCOSI-SAF is used by health-care office staff to rate their own level of patient-centered cultural sensitivity. The items that assess various characteristics of health care on both assessment inventories are similar and were generated from focus groups with culturally diverse patients (eg, African American, Hispanic/Latino, and non-Hispanic white patients) during which these patients were asked to identify specific behaviors, attitudes, and knowledge of health-care office staff that enable patients to feel comfortable with, respected by, and trusting of their health-care office staff.9,14
The specific purpose of the present study is 2-fold. First, this study sought to establish the final version of the T-CSHCOSI-SAF through the use of factor analyses applied to the items on the pilot version of this inventory. Second, this study sought to determine the internal consistency and reliability of the resulting factors/subscales of the final version of the T-CSHCOSI-SAF.
Method
Participants and Procedure
The present study was part of a large national study investigating the characteristics of patient-centered culturally sensitive health care and included 3 steps. In step 1, the research team identified and recruited health-care sites that serve primarily ethnic/racial minorities and low-income patients. These health-care sites were located in the Midwest, Northeast, South, and West regions of the United States.
In step 2, administrators who agreed to have their health-care site participate in the study identified a staff person to be a data collection coordinator (DCC) who in turn identified 2 community members to be data collectors (DCs). The DCCs for each site then received telephonic training and recruitment and participation materials (ie, payment release forms, informed consent forms, and assessment batteries by mail).
In step 3, health-care office staff received (from the DCs) an invitation letter to participate in the study and study materials (eg, assessment battery). The health-care office staff members who chose to participate completed an informed consent form, which included their name, and the assessment battery, which was anonymous. Each participating health-care office staff then returned their signed informed consent form and their completed assessment battery to a DCC in separate sealed envelopes. The full procedures pertaining to the recruitment of health-care sites and study participants, as well as study implementation, are discussed in detail elsewhere.3 Prior to study implementation, Institutional Review Board approval was obtained from the host institution.
Data for the present study were collected from 510 health-care office staff at 67 volunteer health-care centers throughout the United States. Criteria for health-care office staff to participate in this project were as follows: (1) be at least 18 years old, (1) be employed as office staff at 1 of the 67 health-care sites participating in the project, and (3) be able to communicate either verbally or in writing in English and/or Spanish.
Of the 510 health-care office staff, 56 (11%) were males, 446 (87.5%) were females, and 8 individuals did not report their sex. This sex composition is reflective of the higher national proportion of females working in office staff positions when compared to males.15 In terms of race/ethnicity of the study participants, 40% were white, 28% were Hispanic/Latino, 19.4% were African American, 4.9% were Asian/Asian American, 0.4% were American Indian/Native American, 2.5% identified as other race/ethnicity, and 4.7% did not report their race/ethnicity. The sample’s age distribution was as follows: 18 to 24 (8.8%), 25 to 34 (30.9%), 35 to 44 (26.3%), 45 to 54 (22%), 55 to 64 (9.5%), and 65+ years (2.4%). A few (1%) participants did not report their age.
Measures
For the purpose of this study, the following 2 questionnaires were used:Demographic data questionnaire for office staff (DDQ-OS): The DDQ-OS was designed to collect demographic information on each office staff participant including gender, age, race/ethnicity, and professional title.
Pilot tucker-culturally sensitive health care office staff inventory-office staff form (T-CSHCOSI-SAF): This 62-item pilot inventory is a self-assessment instrument for use by health-care office staff to report their self-perceived level of patient-centered cultural sensitivity during their interactions with patients. This pilot inventory consists of the same items as those on the pilot version of the T-CSHCOSI-PF—an inventory used by patients to rate their perceived level of patient-centered cultural sensitivity by office staff.14 Items on the pilot T-CSHCOSI-SAF are rated on a 4-point Likert-type scale in which 1 = “strongly disagree” and 4 = “strongly agree.” Sample items include “I take time with our patients” or “I know our patients’ names.”
Results
Exploratory Factor Analysis
In order to determine the latent factor structure of the pilot T-CSHCOSI-SAF, an exploratory factor analysis (EFA) using MPLUS 7 was conducted on the 62 items constituting this pilot inventory. An oblique, promax rotation was employed, given the expected correlation between factors.16
The investigators explored a 2-factor structure using a priori knowledge based on factor analyses of variants of the pilot T-CSHCOSI-PF, which resulted in 2 factors in the final version of this inventory: Sensitivity/Interpersonal Skill and Professionalism/Punctuality/Responsiveness.3 The scree plot of eigenvalues was examined to corroborate a 2-factor model using the data from the pilot (T-CSHCOSI-SAF). A point of inflexion was observed about the third factor, suggesting a 2-factor model.17 In order to increase the interpretability of the factor solution, an iterative approach was practiced.18,19 This process resulted in the retention of 49 of the original items, which are described in Table 1.
Table 1. Standardized Factor Loadings for the 49-Item Confirmatory Factor Analysis.a
Interpersonal Skills/Professionalism Responsiveness/Sensitivity/Fairness
OS Item 25, respect 0.920
OS Item 3, polite 0.906
OS Item 1, friendly 0.885
OS Item 2, helpful 0.850
OS Item 10, pleasant in person 0.849
OS Item 26, treat like person, not number 0.842
OS Item 5, considerate 0.827
OS Item 15, professional 0.824
OS Item 22, attention 0.815
OS Item 59, communication skills 0.804
OS Item 19, show concern 0.773
OS Item 58, treat patients equally 0.756
OS Item 24, listen 0.752
OS Item 12, willing to please 0.744
OS Item 6, encouraging 0.729
OS Item 13, people skills 0.724
OS Item 62, show care 0.723
OS Item 11, pleasant on phone 0.717
OS Item 49, take time 0.676
OS Item 8, humble 0.663
OS Item 39, confidentiality 0.651
OS Item 60, offer help 0.605
OS Item 51, respond quickly to provider requests 0.462
OS Item 45, efficiency 0.454
OS Item 31, care for soon after entering 0.755
OS Item 30, admit quickly 0.748
OS Item 36, allow reschedule 0.742
OS Item 47, acknowledge arrival 0.725
OS Item 33, get provider to see patient at appointment time 0.723
OS Item 16, reminder cards 0.720
OS Item 35, inform patients of changes 0.695
OS Item 27, fair decisions 0.690
OS Item 37, focus more on patients in room vs. on calls 0.679
OS Item 34, quickly process paperwork 0.677
OS Item 17, reminder calls 0.634
OS Item 50, immediately put patients on hold 0.633
OS Item 38, close sliding door 0.629
OS Item 52, inform patients of costs 0.620
OS Item 32, threaten collection agency 0.600
OS Item 54, put patients on hold long time 0.581
OS Item 55, explain bills 0.571
OS Item 21, assist with payment 0.503
OS Item 56, follow up 0.499
OS Item 48, assume cheating behavior 0.486
OS Item 53, Send accurate bills 0.463
OS Item 29, grab patients’ children 0.455
OS Item 28, know patient names 0.449
OS Item 42, prepare patients 0.432
OS Item 57, mail forms 0.412
aAll loadings significantly greater than zero, P < .001.
The 2-factor model produced a root mean square error of approximation (RMSEA) fit index of .05 suggesting a close fit.20 The 2-factor model included factor 1 (interpersonal skills/professionalism) and factor 2 (responsiveness/sensitivity/fairness) and explained on average 53% of the variance in the set of predictors. The 2 factors produced a correlation of .367.
Internal Consistency and Reliability
Reliability and internal consistency were examined using the results produced by the 2-factor EFA. Cronbach α was calculated for each of the 2 latent factors to examine internal consistency. The 2 factors of the T-CSHCOSI-SAF, Interpersonal Skills/Professionalism (α = .916) and Responsiveness/Sensitivity/Fairness (α = .912), evidenced excellent internal consistency.21
Confirmatory Factor Analysis
A confirmatory factor analysis (CFA) was used to test the fit of the 2-factor model. The comparative fit index (CFI) and the Tucker-Lewis Fit Index (TLI) produced indices of .925 and .921 respectively, suggesting an excellent fitting model.22–24 The RMSEA value of .06 (P < .05) suggests a reasonable error of approximation.23 Factor loadings for the final 2-factor solution are provided in Table 1.
Discussion
The present study sets forth an inventory for health-care office staff to self-assess their level of patient-centered cultural sensitivity in interactions with culturally diverse patients—an inventory called the T-CSHCOSI-SAF. The T-CSHCOSI-SAF was developed through performing factor analyses on data collected using the pilot version of the T-CSHCOSI-SAF.
The evidence in this study indicating that the T-CSHCOSI-SAF may be a promising and reliable inventory for use among health-care office staff has several implications. First, the T-CSHCOSI-SAF can be completed by health-care office staff to facilitate their awareness of (1) the specific behaviors, attitudes, and knowledge that indicate patient-centered cultural sensitivity by healthcare office staff and (2) their self-ratings of their level of display of these behaviors, attitudes, and knowledge. These self-ratings of patient-centered cultural sensitivity by health-care office staff can be used to guide and tailor training of these staff. Furthermore, this training can be organized to focus on the 2 distinct subscales of the T-CSHCOSI-SAF: (1) Interpersonal Skills/Professionalism and (2) Responsiveness/Sensitivity/Fairness.
In future research, the T-CSHCOSI-PF (ie, an inventory that allows patients to rate the patient-centered cultural sensitivity of the office staff at their healthcare site) and the T-CSHCOSI-SAF could be used in tandem to identify discrepancies between patients’ ratings of the cultural sensitivity of their office staff and these same office staff’s self-assessment of their personal level of patient-centered cultural sensitivity. Discrepancies may help inform training of health-care office staff to display patient-centered cultural sensitivity in interactions with culturally diverse patients. Finally, the inventory could be used to encourage introspection, self-reflection, and increased self-awareness of patient-centered cultural sensitivity among office staff as a means to improve PC-CSHC.12
There are noteworthy study limitations that should be considered when interpreting the present study findings. First, the self-report T-CSHCOSI-SAF developed in this study may encourage socially desirable responding. However, self-report measures are commonly used in and valued in health-care research and practice.25 Additionally, some researchers recommend the use of external assessments (eg, external observation) as a more accurate way to assess cultural competence.26 Given this recommendation, it may be helpful to use external assessments such as external observations of the occurrence of health-care office staff displays of patient-centered cultural sensitivity, in addition to their self-assessments of their cultural sensitivity using the T-CSHCOSI-SAF.
Furthermore, findings from this study are based on a convenience sample of health-care office staff. In an effort to recruit culturally diverse health-care office staff from a variety of different health-care sites across the United States, health-care office staff participants were not randomly selected, which in turn limits the generalizability of the present study findings.
Future research is needed to establish the reliability of the T-CSHCOSI-SAF when it is used by randomly selected health-care office staff in diverse settings over an extended period of time. Such research will further ensure use of the T-CSHCOSI-SAF to promote patient-centered cultural sensitivity by healthcare office staff and thus foster overall patient-centered culturally sensitive health care—care that has been linked to improving health-care quality and reducing the health-care disparities that plague the United States.
Declaration of Conflicting Interests: The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding: The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: Financial support for this research was provided by the Robert Wood Johnson Foundation.
Author Biographies
Carolyn M. Tucker, PhD, is a professor in the Department of Psychology at the University of Florida in Gainesville, Florida.
Whitney A. Wall, PhD, is an assistant professor in the Department of Psychology at Fayetteville State University in Fayetteville, North Carolina.
Guillermo Wippold, MS, is a research associate and doctoral candidate in the Department of Psychology at the University of Florida in Gainesville, Florida.
Julia Roncoroni, MS, is a research associate and doctoral candidate in the Department of Psychology at the University of Florida in Gainesville, Florida.
Michael M. Marsiske, PhD, is an associate professor in the Department of Clinical and Health Psychology at the University of Florida in Gainesville, Florida.
Gabriel S. Linn, BS, is a research associate at the University of Florida in Gainesville, Florida.
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Sci AdvSci AdvSciAdvadvancesScience Advances2375-2548American Association for the Advancement of Science 28435862160186110.1126/sciadv.1601861Research ArticleResearch ArticlesSciAdv r-articlesEconomic SociologyFinancialization impedes climate change mitigation: Evidence from the early American solar industry Jerneck Max http://orcid.org/0000-0003-2402-0279Mistra Center for Sustainable Markets (Misum), Stockholm School of Economics, Stockholm, Sweden. Email: max.jerneck@hhs.se3 2017 29 3 2017 3 3 e160186109 8 2016 10 2 2017 Copyright © 2017, The Authors2017The AuthorsThis is an open-access article distributed under the terms of the Creative Commons Attribution-NonCommercial license, which permits use, distribution, and reproduction in any medium, so long as the resultant use is not for commercial advantage and provided the original work is properly cited.How financialization undermines the development of low-carbon industries, exemplified by photovoltaics in the United States.
The article investigates how financialization impedes climate change mitigation by examining its effects on the early history of one low-carbon industry, solar photovoltaics in the United States. The industry grew rapidly in the 1970s, as large financial conglomerates acquired independent firms. While providing needed financial support, conglomerates changed the focus from existing markets in consumer applications toward a future utility market that never materialized. Concentration of the industry also left it vulnerable to the corporate restructuring of the 1980s, when the conglomerates were dismantled and solar divisions were pared back or sold off to foreign firms. Both the move toward conglomeration, when corporations became managed as stock portfolios, and its subsequent reversal were the result of increased financial dominance over corporate governance. The American case is contrasted with the more successful case of Japan, where these changes to corporate governance did not occur. Insulated from shareholder pressure and financial turbulence, Japanese photovoltaics manufacturers continued to expand investment throughout the 1980s when their American rivals were cutting back. The study is informed by Joseph Schumpeter’s theory of creative destruction and Hyman Minsky’s theory of financialization, along with economic sociology. By highlighting the tenuous and conflicting relation between finance and production that shaped the early history of the photovoltaics industry, the article raises doubts about the prevailing approach to mitigate climate change through carbon pricing. Given the uncertainty of innovation and the ease of speculation, it will do little to spur low-carbon technology development without financial structures supporting patient capital.
Keywords
climate changefinancializationcarbon pricingeconomic sociologySchumpeterMinskyindustrial organizationinnovationtechnological changeCopyeditorKen Marvin Ortega
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INTRODUCTION
Reducing carbon emissions to safe levels means replacing the present industrial system. Low-carbon technologies, which are currently marginal, need to become competitive enough to mount a wave of “creative destruction,” to use Joseph Schumpeter’s (1) term, sweeping away fossil fuels. Technological revolutions normally occur when profit opportunities in established industries are exhausted, but this one would have to occur much sooner, engineered through state policy. Ultimately, however, state policy is only as effective as the innovative capacity of private firms. It is therefore concerning that this capacity appears to have been weakened by financialization (2, 3). In the past 40 to 50 years, advanced economies have become increasingly subjected to the vicissitudes of financial markets. Ever-larger amounts of credit have been created to trade existing assets such as real estate rather than productive investments. The most visible effect of this process has been a series of asset bubbles, followed by painful periods of deleveraging [(4), p. 62]. As John Maynard Keynes recognized, capitalist economies always contain the capacity for both “enterprise” and “speculation,” and if left unchecked, the latter will come to dominate over the former. Economists at the Bank for International Settlements have found that financialization harms innovative firms, which operate by creating intangible future assets that are difficult to collateralize (5). This shift has also changed corporate governance, bringing an increase of “financial controllers in the management of corporations” and of “the stock market as a market for corporate control in determining corporate strategies” (6). As a result, firms have become less oriented toward investing to improve their long-term performance and more oriented toward enriching their managers and investors in the short run (3). Reinforced by managerial incentives, increasing amounts of profits are spent on dividends and stock buybacks, leaving less for investment in long-term technological development (7). While the financial sector has grown as a share of advanced economies, nonfinancial firms have become financialized, drawing profits from financial activities and orienting their strategy toward maximizing the value of their financial assets instead of productive ones. Hyman Minsky feared that this process, already visible by the 1980s, would not only cause fragility but also would undermine “the capital development of the economy,” that is, the development of its productive capabilities (8). Instead of serving industrial development, finance had come to serve itself.
Finance is an essential component of industrial change because it allows technologies to be developed before they can generate a return. But if finance no longer serves industrial change but instead prioritizes rent-seeking (seeking to increase its share of existing wealth without creating new sources of wealth), creative destruction of the present carbon-intensive industrial system cannot occur. The aim of this article is to investigate this issue through a study of the emergence of one low-carbon industry, solar photovoltaics (PV) in the United States. The focus is on the period after the first oil shock in 1973 until the end of the 1980s. The case is contrasted with the more successful development of the industry in Japan. In the late 1970s, American firms held 90% of the global market share; by 2005, it had declined to under 10%, whereas the Japanese share had risen to almost 50% (9). Changes to corporate governance and organization brought by financialization are identified as major causes of the difference in outcome.
This study is informed by Schumpeter’s theory of creative destruction, which remains the most useful tool for understanding industrial change; it also is influenced by the financial insights of Schumpeter’s student, Hyman Minsky. Economic sociology will also be applied to analyze the central role of uncertainty in innovation and the social mechanisms to overcome uncertainty in concrete social and institutional conditions. These insights will be outlined in a rather lengthy theoretical section. The goal is to provide a coherent synthesis of three large and synergistic bodies of work, ranging from a stylized view of the microlevel interactions between entrepreneurs and financiers (and workers) up to the macrolevel of institutional arrangements of comparative capitalisms. Beyond shedding light on the emergence of the industry under study, this synthesis might be used to guide other similar studies. A more comprehensive study would include an in-depth analysis of industrial policy and the social forces behind it, but as the study will show, changes to corporate governance were major determinants of the outcome because industrial policy was dominated by large firms in both countries.
The article concludes with a discussion of implications for low-carbon industry development in the future. The study highlights the tenuous and conflicting relationship between finance and production, calling into question proposals to mitigate climate change based on the assumption of a harmonious relationship. Carbon pricing rests on the idea that, if government policy makes one industry uncompetitive, finance will automatically flow to another. This article indicates that such a result can only be expected under certain conditions, which do not appear to apply in the advanced world at the present.
Finance and innovation
Finance is an integral component of innovation because it allows technologies to be paid for before they exist. It acts as a bridge between the expectations of future profit and the ability to realize it by assembling the needed resources in the present. By creating new purchasing power in the process, finance also expands the money in circulation, thereby allowing aggregate profits to exist (10). This makes finance the defining feature of capitalism, a system that evolves through continuous forward-looking investment in new capabilities, motivated by the prospect of using them to produce output for profit. When private and public banking merged into a coherent financial system in early modern Europe, it created the “infrastructural power” needed for a transition from feudalism to capitalism (11). Pools of safe financial claims to real wealth enabled the application of long-term rational calculation to industrial production [what Weber defined as the essence of capitalism (12)], and the widespread circulation of these claims created markets where profits from this rationalized production could be realized.
Joseph Schumpeter noted that introducing a financial sphere into a static economy makes it dynamic (13). It orients the economy toward the future, changing calculations of economic value from including only existing resources to also including those resources that might be expected to exist in the future. As a result, the horizon opens up to potentially infinite possibilities for technological advances. This shift also introduces a certain fictitious quality to the economy because the future is unknowable and expectations will inevitably diverge from actual outcomes. Financial claims correspond to the value of real assets, but the correspondence is never absolute. This separation between present and future value that finance introduces is what gives capitalism its instability. Schumpeter saw that finance destabilizes the economy by enabling entrepreneurs to introduce innovations that cause creative destruction. However, it can also be destabilizing in a different way. Finance has a tendency to decouple from production and fuel asset bubbles instead of industrial change. It then becomes a tool of value extraction instead of creation, a process that we now recognize as financialization. Schumpeter had a lucid analysis of the role of finance in production, but the full implications were better explored by his student Hyman Minsky. The theories of both will be used to guide the empirical study. The future orientation of technological development also calls for an inclusion of economic sociology into the analysis to account for the formation of perceptions and social mechanisms to overcome uncertainty. Sociology is also needed to account for the fact that capitalism, as Schumpeter and Minsky insisted, is an evolutionary system that interacts with changing institutions over time. What follows is a summary of Schumpeter’s views of the role of finance in industrial development, Minsky’s additions, and a set of sociological tools to situate their universal logic in concrete social and institutional settings.
Because it takes time to assemble innovations before they can generate a return, Schumpeter argued that the process must be paid for in advance. The mechanism that makes this possible is credit. That is why Schumpeter defined capitalism as a system “in which innovations are carried out by means of borrowed money” [(14), p. 223)]. He viewed the financial system as the “headquarters of capitalism,” determining which technologies are allowed to emerge [(15), chapter 3]. Capitalist production depends upon the interaction of two roles, the financier and the entrepreneur. The financier owns monetary claims to real wealth and operates by leveraging them in pursuit of more claims. The entrepreneur operates by producing the real wealth that makes financial claims valuable in the first place. In Schumpeter’s view of capitalism, financiers create credit for entrepreneurs, who spend it into existence in the act of investment; the bank notes circulate as money throughout the economy and end up as profit on the balance sheets of the most innovative entrepreneurs, allowing them to repay the debt. If there is money left, they can plow it back into further innovation, repeating the circuit on a larger scale. An expanded market share can act as a staging ground for increasingly capital-intensive innovation, creating barriers to entry for new entrepreneurs; however, as long as these have access to credit, they can introduce innovations that make the technologies of incumbent firms obsolete. This system of decentralized credit creation for innovation and continuously reinvested profits makes for a highly dynamic economy in which the means of production are continuously revolutionized.
In Schumpeter’s view, finance is subordinated to production. He built his dynamic theory of capitalism by introducing a financial sphere into the static economy of Leon Walras and never abandoned Walras’ model of an economy in which all productive resources were fully used (16). Hyman Minsky was able to advance on this view by incorporating crucial insights from John Maynard Keynes (16). Keynes argued that the existence of money as a store of wealth allows capitalists to leave productive resources unused. The traditional economy has only one price level for consumption goods. In Schumpeter’s theory, one can also find a price level for capital goods, that is, machinery and plant, which are expected to produce the consumption (and capital) goods of the future. In Keynes’s view, a capitalist economy also has a separate price level for financial assets. The difference in price between capital and financial assets determines real investment. When the expected return on capital goods exceeds the return on financial assets (that is, when demand is strong), capitalists will choose investment. When the expected return drops below the expected return on financial assets, capitalists will hoard their cash or spend it bidding up the value of financial assets. Because investment becomes the incomes that generate demand, the process is self-reinforcing.
Keynes differentiated between “enterprise” and “speculation”; the organization of money markets determines which one will prevail. “When the capital development of a country becomes the by-product of the activities of a casino,” he argued, “the job is likely to be ill done” (17). Minsky went on to explore what happened when innovation within the financial sphere itself causes it to decouple from production, spinning off into a self-referential loop of speculation (18). Even if the financial system begins as subordinated to production, financial innovators will find easier ways to make money. If left unchecked, innovative and profit-seeking financiers will break free of constraints and turn to speculation. Thus, finance becomes an instrument of rent-seeking.
Hence, what is missing from Schumpeter’s theory is the fact that innovation is not the only use for which credit can be created: It can also be created to buy existing assets, in which case it does not fuel creative destruction but asset bubbles. There is also a limit to how much profit firms can reinvest. Production under capitalism is carried out for profit, and some point in the circuit profit will be extracted from the enterprise to be stored as liquid wealth. Only if capitalists are as austere as the monk-like toilers of Max Weber’s The Protestant Ethic and the Spirit of Capitalism, and as confident in the future as to keep no amount of their wealth in cash, would they reinvest all their profits in production. As Keynes famously recognized (19), the common practice of storing wealth in cash and existing assets leaves real resources in the economy unused. As long as hoarding and speculation are available as options to financiers, their willingness to invest in innovation is limited. It is safer to live off the income streams of past investments, as “rentiers.” A fully production-oriented economy is only possible if the financial component of capitalism is entirely subordinated to the entrepreneurial function, in which case it might no longer be recognizable as capitalism at all, but rather a centrally planned economy where decentralized financial decisions are curtailed.
Compared to the safety of lending for existing assets, innovation is an uncertain activity that prudent financiers tend to avoid. They are particularly unlikely to finance new and unproven entrepreneurs who face powerful competition from incumbent firms. Established firms can use retained earnings to innovate but tend to do so in ways that build on their existing capabilities, not in ways that make them obsolete. Innovation is rarely economically rational; as the economist and venture capitalist William Janeway puts it, it is dependent on “sources of funding that are decoupled from economic concern” (20). In the early stage, this usually means the state, which is free from financial constraints and guided by noneconomic goals such as national security (or hopefully, if under sufficient popular pressure, concern about climate change). At a later stage, financially unconcerned sources of funding may also include irrationally exuberant investors caught up in the speculative manias, which often surround new technologies. Hence, while speculation undermines creative destruction when it involves existing assets, a certain amount of it that is directed at new technologies is often necessary for it to take off. Neo-Schumpeterian economist Carlota Perez ascribes a certain temporal logic to the process: Financial capital tends to back new technology in the deployment phase, often creating a bubble that draws in sufficient resources for the technology to succeed. When profit opportunities are exhausted, it leaves to seek out new ones, which may include innovations.
In empirical studies, the universal logic of this model needs to be augmented with contextual detail. Whether financiers invest in creative destruction or not depends on the opportunities and constraints afforded them by specific institutional arrangements. Both Schumpeter and Minsky insisted that capitalism is an evolutionary system that adapts to institutional change. As Schumpeter stressed, economic sociology is therefore needed as a “bridge between theory and history” (21).
Another reason to view creative destruction through a sociological frame is the inherently uncertain nature of innovation and the centrality that perceptions of the future this entails. As game theory indicates, isolated individuals acting under uncertainty lead to suboptimal “prisoner’s dilemma”–type outcomes. Uncertainty compels actors to adopt a prosocial orientation, turning market transactions into hierarchical transactions and limiting transactions to known parties and those with a reputable standing, among others (22). Interaction is made less uncertain through “social devices” such as habits, institutions, organizational structures, and outright domination (23, 24). Because the future is unknowable, investment decisions are always made on the subjective basis of confidence in the future, what Keynes called “animal spirits.” Routine investments can be made by extrapolating past trends into the future, but investments in innovation must be based on more elaborate “fictional constructions” of future states (24). These are constructed by the various actors involved in the innovation process and must be shared by them if the innovation is to succeed.
The collective nature of innovation calls for a relational perspective, in which actors are analyzed not only on the basis of their individual characteristics but also by how they relate to each other. This applies to the various actors needed to cooperate in the innovation process, beginning with the entrepreneur and the financier. If they succeed in turning the venture into an enterprise, they must also resolve the tension between manager and employee. The tension within the capitalist class, between the entrepreneur and the financer, and between capital as a whole and labor also interact with each other in institution-specific ways.
The relational perspective is also needed to analyze competition between firms. Creative destruction is a power struggle between incumbents and challengers, which devise strategies by taking each other’s presumed actions into account. The power balance is observed by financiers, who restrict finance to what they perceive to be the winning side. As Weber argued, finance is a weapon in the struggle for economic existence (25).
As the guarantor of the financial system and arbiter of market competition, the state plays an inescapable role in creative destruction. States may keep financial flows under strict control or allow financialization to proceed unhindered. The state is also a major source of spending and often sets the direction of innovation through industrial policy. The points made above will be elaborated in a series of propositions to guide the empirical study.
Proposition 1: Innovation is uncertain
Innovation is, by definition, an uncertain activity whose outcome is unknowable. For financiers,There is uncertainty about the talent of the entrepreneur, the market need for the product, the development of a saleable product, the raising of second-round financing for working capital and expansion; the manufacturing of the product, competitors’ responses, and government policies [(26), p. 137].
Decisions to invest in innovation can therefore not be made on the basis of probabilistic calculation. As Jens Beckert argues, they must be based on fictional constructions of the future (24). These are socially constructed, if only in the sense that they must be shared to be realized. Collectively held expectations create the certitude necessary to commit resources to uncertain projects. As long as they do not stray too far from real technological constraints, they can be self-fulfilling.
New industries begin as visions in the minds of entrepreneurs. In the early stage, there are various such visions competing with each other. As the industry matures, the list of alternative designs is narrowed down, until a dominant one is arrived upon, to the exclusion of others (27). The dominant design will then be improved upon with use and made increasingly dominant through learning, economies of scale, and network effects. When studying technological trajectories, it is therefore important to examine the visions held by the involved actors, how they were formed, and how they shaped the outcome.
Proposition 2: Uncertainty is overcome through cooperation
For new entrepreneurs, there is no history of income statements for financiers to evaluate or existing assets to be pledged as collateral. There is only an intangible idea, which can only be judged on the basis of expected future profitability. Financiers who determine which projects to fund must do so, on the basis of detailed knowledge attained from, and about, the entrepreneur. This makes financing an inherently social process, “embedded in relations of a strikingly personal sort” [(28), p. 137]. Even in the most mundane forms of banking, Schumpeter [(14), pp. 116–117] noted,The banker must not only know what the transaction in which he is asked to finance and how it is likely to turn out, but he must also know the customer, his business, and even his private habits, and get, by frequently ‘talking things over him’, a clear picture of the situation. But if banks, whether technically so called or not, finance innovation, all this becomes immeasurably more important.
To overcome uncertainty, the entrepreneur and financier need to collaborate closely, sharing the entrepreneur’s knowledge of production with the financier’s knowledge of markets. Because there is no objective metric to evaluate whether an innovation will succeed and the loan will be repaid, creditworthiness is “socially constructed” in the interactions between them [(29), p. 251].
Entrepreneurs’ ability to attain finance is largely determined by their network position. Ideally, it combines close ties that transmit the trust needed to maintain a credit line with ties to more distant connections that provide access to more remote information and market opportunities (30). Venture capitalists, who specialize in early-stage funding, need to be “rich in relationships even more than cash” (31). They operate by bridging “structural holes” in networks between entrepreneurs and large institutional investors (32, 33). Entrepreneurs seeking to construct innovative enterprises do so by harnessing the power of their networks to gather resources, discover opportunities, and gain legitimacy (27).
Although Schumpeter emphasized the role of the financial system as the handmaiden of creative destruction, he probably overestimated its role in funding new enterprises, which was uncommon even in his day (34). Most new ventures are financed by the entrepreneurs themselves or by money from family and friends (35). Early-stage finance often has “affective and charitable dimensions” [(36), p. 1688]. As Janeway argues, new technologies need support of a non-economic nature (20). The importance of cooperation to reduce uncertainty makes it important to pay attention to the concrete relations between entrepreneurs and financiers when studying the emergence of new industries.
Proposition 3: Investment decisions have signaling effects
Investment decisions are observed by actors other than the directly involved parties. If one financier grants a loan to an entrepreneur, it sets off a “sociological multiplier” that signals to other financiers that the venture is a sound investment [(37), p. 55]. Conversely, if one financier rejects an investment, it signals to others that it might be wise to do the same. This effect makes it important to study how investment decisions affect other parties through signaling.
Proposition 4: Financial flows are shaped by power configurations between incumbent and challenger firms
New entrepreneurs face the entrenched power of established firms (38). Incumbents seek to stabilize their position by integrating upstream or downstream, diversifying into new lines of business, or seeking protection from the state. Challengers have to operate within the constraints set up by incumbents until they gather enough strength to dislodge them. Power asymmetries between incumbents and challengers are observed by financiers and shape their lending decisions. Market power is considered in financial evaluations of firms, allowing them to borrow on better terms than challengers (8). O’Sullivan [(39), p. 6] suggests that “we could ask whether incumbent firms dominate because they are more innovative or because entrants are too financially constrained to compete with them.” It is therefore important to examine how an industry was shaped by dynamics between incumbents and challengers.
Proposition 5: Infant industries need protection
Uncertainty and market power are hostile forces from which infant industries need protection until they mature. Schumpeter (1) argued that these could be provided by the monopoly power of large corporations, which allows them to cross-subsidize new product lines with their existing ones. Because firms rarely innovate in ways that would undermine their existing capabilities, the protected spaces for radical new low-carbon technologies would likely have to be provided by the state (40). As Kenney and Hargadon (41) demonstrate, private venture capital is not a viable model for most low-carbon technologies, which are capital-intensive and in direct competition with existing alternatives. Therefore, analyzing industry emergence makes it necessary to find out the extent to which immature technologies allowed protected spaces to mature.
Proposition 6: Finance and production have different logics, driving them apart
Fruitful cooperation between entrepreneurs and financiers is not guaranteed because they have different objectives. The goal of the entrepreneur is to expand production, and money is a mean to this end. The goal of the financier is to make money, and production is one, but not the only, mean to this end. If the financier could, he would rather skip the production phase altogether and turn money directly into more money. As Keynes observed, if there is easy money to be made by speculating on the future price of financial assets, capitalists will avoid investing in capital assets (8). Because financial firms are profit-driven actors just like all others, Minsky recognized that financial innovators will inevitably find ways of making a profit without having to engage in production. Others will follow their lead, eventually raising pressure on the state to legitimate financial innovations and give new financial instruments parity with state currency in the interest of maintaining financial stability.
The tension between the entrepreneurial and financial component of innovation can be resolved because both have a mutual interest in assuring that the loan will be repaid. However, circumstances determine whether the financier will want this to occur through the continued operations of entrepreneur’s enterprise or by having it liquidated. Following Carlota Perez, the entrepreneur can be seen as a representation of “production capital,” which is tied down in equipment, personnel, knowledge, and routines, whereas the financier represents “financial capital,” which is free to move [(42), p. 6].Production capital is the agent for the accumulation of wealth making capacity; its natural horizon is long-term and it remains tied to its expertise. Financial capital is the agent for reallocating wealth in order to constantly maximize short-term returns. Production capital is therefore path-dependent while financial capital is fundamentally footloose and flexible.
While production capital is oriented toward expanding production, financial capital is oriented toward the moment when production is concluded and output is converted into money. Financiers and entrepreneurs can thus be defined as “the embodiment of two different moments in the circuit of capital” (43).
Finance has a disciplining effect on production capital, compelling it to increase efficiency, reduce costs, and provide products that customers want. However, it may impede the ability to develop entirely new products for markets that do not exist, which is an inefficient process of trial and error. Financial capital may aid creative destruction by redeploying resources from old to new industries. However, it may lack the patient capital to sustain them. The outcome is an empirical issue that varies between times and places, making it important to be attuned to historical and institutional analysis. Just like Schumpeter, Minsky saw capitalism as a system evolving through time, taking different forms under different institutional regimes. After financial speculation caused the Great Depression, finance was reined in during the managerial era, which, in turn, was followed by the era of money manager capitalism, in which finance again was allowed to break free (16). Given the differing logics of finance and production, it is important to ask how firms maintain “financial commitment.”
Proposition 7: The balance of power between financial and production capital affects firm strategy
In small firms, strategy can be set by the founder because ownership and control are vested in the same person. As the firm grows, these issues can become contested. Founders who want to leave their creations intact when they retire can make a profitable exit by selling shares in the enterprise on the stock market and leave it in the hands of the manager. Buyers of the stock become owners of financial claims on the enterprise but do not necessarily exercise control over the enterprise. In this case, financial control over production is diminished. When firms pay down debt and rely on retained earnings, the balance of power shifts from financial to production capital. The separation of ownership and control can lead the balance of power to shift in favor of productive capital, as was the case during the managerial era (44). After the Second World War, Minsky argued, deficit spending by the American government allowed corporate profits to rise to the level where corporations did not have to rely on external finance (16). This gave them managerial autonomy, allowing them to focus on long-term technological development. Although financial evaluations are based on publically available information, investments can be made out of retained earnings on the basis of specific knowledge of the firm’s capabilities that are only available to the firm itself. Hence, by relying on retained earnings, firms can free themselves of financial control and separate innovation from the incompatible logic that animates financial markets. This dimension of strategic control is essential to innovation (45).
The development led Keynes to perceive a tendency for “the big enterprise to socialize itself” and have it run in the interest of managers and employees instead of shareholders (46). Ultimately, this would lead to the “euthanasia of the rentier.” A side effect, according to Minsky, was that corporate organization descended into bureaucratization. Although government spending supported profits, only a small part of it went to technological development; the rest was used to underwrite consumption through welfare programs and military spending. Separation of ownership and control can lead to concern about excessive autonomy of managers to pursue growth strategies that do not necessarily make economic sense or only do so on a long-time horizon (47, 48).
The function of finance, it may be argued, is to keep this from happening (43). During the 1980s “shareholder revolution,” financiers reasserted control. Thus, it ended the “independence of corporations from the money and financial markets that characterized the managerial era,” as Minsky argued (16). Instead, a new era of “money manager capitalism” came, in which the “main purpose of those who controlled corporations was no longer upon making profits from production and trade but rather to assure that the liabilities of the corporations were fully priced in the financial market, to give value to stockholders,” leaving “little in the way of internal finance left for the capital development of the economy.” Proponents of shareholder value argued that profits should not be reinvested but that managers should “disgorge the cash” so that other investors can find better use for them [(49), p. 323]. Since then, corporations have, to an increasing extent, become “managed by the markets” (50). The need to satisfy shareholders by meeting quarterly requirements for earnings per share has lead managers to engage in financial engineering, such as stock buybacks, rather than investing in long-term innovation. Companies that manage to invest heavily in long-term innovation tend to be insulated from shareholder pressure through special classes of stock that keep founders in control [(51), p. 12].
Financial control is not necessarily exerted from outside the firm but can be implemented by financially oriented managers from the inside. Neil Fligstein has documented how this process began more than a decade before the shareholder revolution, during the merger wave of the late 1960s when corporations began expanding into unrelated businesses, turning themselves into financial conglomerates and managing their divisions like financial assets in a portfolio of stocks (52). A firm dominated by the agents of production capital tends to take a technology-based, internal diversification strategy, gradually expanding into new areas bordering their existing capabilities. A firm dominated by financial capital will be governed as a portfolio of assets, buying and selling divisions like shares on the stock market. Song [(53), p. 380] distinguishes between internal and external diversifiers in the following way:Internal diversifiers generally exploit any synergies between current business lines and newly added business lines. External diversifiers decentralize operational functions to the operating divisions and concentrate mainly financial and legal control at top-level corporate headquarters.
External diversification can undermine the organizational coherence of the firm and move strategic control from actors that are knowledgeable about production to central headquarters governing through financial metrics. Innovation can be defined as an information creation process that proceeds through a process of small but cumulatively important contributions from those who are technologically knowledgeable (54). Christensen et al. (55) argue that financial control is an “innovation killer” because the richness of tacit knowledge is lost when it is transformed into simple numbers. Financial calculations are incapable of evaluating future technology and therefore invariably overestimate the life expectancy of existing technologies. The significance of power struggles between production capital and financial capital, which shape corporate governance, makes it important to focus on the issue of how actors who are knowledgeable about production processes maintain strategic control.
Proposition 8: The relation between finance and production affects the relation between management and labor
Schumpeterian theory is mainly concerned with the tension within the capitalist class between the entrepreneur and the financier. Innovation is also shaped by the tension between capital as a whole and labor. Production and finance capital both belong to the capitalist class. Their collective goal vis-à-vis workers is to extract as much effort as possible for the least cost. Conversely, workers can be viewed to have the opposite goal, to exert as little effort as possible for as much pay as possible. However, the effort-minimizing worker may predominantly apply to alienated labor. Innovation would not be possible if human beings did not have an inherent will to create, an activity that is rewarding in its own right. The task of the innovative enterprise is to harness this drive. It can be done by sharing productivity gains with workers, giving them long-term careers and the ability to advance within the corporate hierarchy. William Lazonick refers to this solution as organizational integration (45).
Most innovation is incremental, consisting of minor but cumulatively major improvements to processes and products. Workers, who have local, tacit knowledge to upgrade the work process and equipment, are potentially major contributors to the process. When they are barred from participating, or when their tasks are narrowly defined and low-skilled, their incentives and abilities to improve the work process are diminished [(56), part 1]. Production capital and labor share the same preference for stability and long-term commitment. By freeing the firm from shareholder control, it may allow to orient itself to maximize benefits for employees, depending on institutional arrangements. When studying innovation, it is therefore important to examine to what extent firms achieve organizational integration.
Proposition 9: Tensions are resolved with national institutional arrangements
Innovation depends on the fruitful integration of the three nodes of financial capital, production capital, and labor. Their interrelation is regulated by different institutional arrangements in different countries. Finance and production are not naturally connected; it takes conscious institutional bridging to achieve that, often occurring during extraordinary political events such as economic depression or war. Path dependency then tends to reinforce them.
As Roy (57) points out, finance and manufacturing in the United States had different historical origins and remained separated until they were joined together by the Civil War, laying the foundation for the corporate system of today. In Japan, the Asia-Pacific War had a similar effect, creating the close-knit nexus between industrial firms and banks of the postwar era (58). Corporate ownership was separated from control in both countries after the Great Depression, freeing the agents of productive capital from the constraints of financial capital (44). However, the tension reemerged forcefully in the United States, particularly with the “shareholder revolution” of the 1980s (59).
Labor unrest shook both countries in the wake of the Second World War but was resolved differently. In Japan, workers’ interests were aligned with management through vertical enterprise unions and lifetime employment. In the United States, horizontal labor unions remained strong enough to secure a truce with management, but blue collar workers remained segmented from management, not integrated with it, as in Japan.
Financialization is caused by nothing more than the removal of political constraints on finance. Krippner (60) documents how this process, called depoliticization, has unfolded over the past decades in the United States. Depoliticization was a solution to the political problem of overt redistribution between interest groups. By deregulating finance and letting markets decide where finance should flow, politicians freed themselves from the responsibility of choice. Decision-making was moved from the realm of politics, where policy makers bear responsibility, to the realm of impersonal decision-making, either through technocratic control or to market forces.
This kind of institutional change has a profound effect on the financial structures that determine industrial change. The comparative study must therefore be attuned to the way in which the industry’s development is shaped by national institutional arrangements in the two countries. The following section will trace the evolution of the American PV industry from 1970 to 1989, framed by a comparison with the industry in Japan.
RESULTS
After the 1973 oil crisis, American policy makers and firms made serious efforts to develop a viable solar PV industry. Despite optimistic projections and initial global dominance, the American industry did not take off. Japanese firms began making inroads in the early 1980s; by 2005, they had captured almost half of the global market, whereas the American share had decline to 9% (9). The industry’s center of gravity has since then moved toward China and Taiwan (61).
The disappointing performance of the American solar energy industry in the 1980s could be seen as the result of falling energy prices or flawed government policy, particularly the cuts under President Reagan (62). As this article emphasizes, however, the American solar strategy had underlying weaknesses to begin with. Solar cells were first given a protected space to develop in NASA’s space program, where they were used to power satellites (63). The subsequent development of the terrestrial American PV industry can be divided into three overlapping phases. First, a handful of small entrepreneurial firms pioneered the technology. Then, as the 1970s progressed, most of them were purchased by large conglomerates in the oil and electronics industries. Finally, in the 1980s, the conglomerates were broken up and their solar divisions were dismantled or sold off to foreign firms. There were large differences in how the original entrepreneurs and the large conglomerates viewed the future of the industry.
Two visions
In the early 1970s, when the American solar energy industry did not yet exist, there were two competing visions of where it should head. One camp consisted of a small number of entrepreneurs who had been involved in producing solar cells for the space program or pioneered their application on Earth. They envisioned an industry of small-scale energy production off the grid [(63), p. 57; (64)]. Solar energy was too expensive to compete with conventional sources but had the advantage of being usable in remote locations or at sea. The pioneers saw a reasonably large potential in selling solar panels for these applications as roadside emergency phones, signaling systems for train crossings, electric fences, mountain-top communication centers, African villages, navigational aids, and consumer electronics. These markets could be served by small firms, without much investment in research or large production facilities. Profits from these sales could then be plowed back into technical improvements, enabling a further and gradual expansion of the market to less-remote locations until the technology was viable for widespread use. Modest policy measures, such as mandating solar-powered lights at remote train crossings, were considered more helpful to spur the industry than lavish research grants [(63), p. 78]. The pioneers were later joined by a grassroots movement of Jeffersonian environmentalists who viewed decentralized energy as a means to escape the centralized power of large corporations and the state.
The other camp consisted of the energy policy bureaucracy and closely affiliated large manufacturing and energy corporations along with utilities (65). This camp was wedded to the idea of utility-scale PV generation, competing directly with conventional sources of energy. Official estimates held that this would become a reality sometime by the mid to late 1980s. Proponents of this view favored a massive increase in research and development to improve the efficiency of solar cells in the laboratory until they could compete with centralized energy production. A rapid move toward large-scale mass production was considered necessary to bring down costs. Both activities were capital-intensive, which meant that they needed to be conducted by large corporations. This preference had both ideal and material causes. The U.S. Energy Research and Development Agency that was responsible for developing PV was made up mostly of members from the recently disbanded U.S. Atomic Energy Commission. Their views were shaped by the experience of nuclear energy, a technology where large-scale and centralized energy production was the norm. Large manufacturing corporations also had a natural preference for large scale and centralization, and the research and production subsidies it would bring. In addition, naturally, utilities did not want decentralized energy producers as competitors.
Unsurprisingly, the large-scale vision prevailed. Apart from a brief period during the Carter administration when environmentalists were publically prominent, official policy overwhelmingly favored large corporations, granting them subsidies, tax breaks, and research assistance that helped them cement their position (66, 67). The orientation toward large corporations stood in stark contrast to state policy to promote semiconductors two decades earlier, which had a competition-enhancing orientation favoring small entrepreneurial firms (68, 69). The fact that American policy toward PV greatly favored large corporations would not necessarily have been a problem because large corporations also controlled the policy process in Japan (70). However, Japanese corporations, and hence policy makers, were oriented toward near-term markets instead of the future utility market [(71), p. 63]. As the study will emphasize, the main differences between the American and the Japanese trajectories reflected differences in industrial and corporate organization.
Phase 1: Struggling entrepreneurs
The terrestrial American solar PV industry was founded by a handful of entrepreneurs. Their main difficulty was finding willing investors who could provide financial commitment. They managed to gather enough money from family and friends and sometimes more distant investors to launch their enterprises [(64), p. 20; (72), pp. 69; (76)], but they soon found it difficult to attain the needed funds to expand.
The first American PV firm to focus on the terrestrial market was Solar Power Corporation (SPC), founded in 1973 by Elliot Berman. He originally took his idea to a number of venture capitalists, but they “weren’t very venturesome” and declined the offer [(63), p. 53]. Instead, he turned to the oil company Exxon, which made SPC a subsidiary after Berman had convinced executives that solar panels were cost-effective for offshore oil platform lighting, pipeline corrosion protection, and surveying equipment. Others took notice and the oil industry soon became one of the most important markets for solar cells [(63), p. 66]. However, the involvement of oil companies would prove a mixed blessing.
The second firm to emerge was Solarex, also founded in 1973 by Hungarian immigrants Joseph Lindmayer and Peter Varadi. They did not have any luck courting venture capitalists either, visiting 20 of them without success, and developing “allergic reactions if somebody mentioned the word ‘venture capitalist’” in the process [(64), pp. 19, 192]. Bill Yerkes, who founded the third major PV firm Solar Technology International (STI) in 1975, visited an estimated 75 venture capital firms [(73), p. 44] before selling his firm to the oil company Arco 2 years later.
These three firms—SPC, STI, and Solarex—dominated the industry, holding around 80% of the American market into the 1980s (74). If they had trouble securing venture capital, less-prominent firms had no greater luck. Robert Willis who founded Solenergy was turned down by 10 venture capitalists, reporting that they were not interested in risky ventures but in established but fast-growing concerns [(75), p. 13]. Paul Maycock, who managed the U.S. Department of Energy’s PV program, assisted several small firms in their efforts to raise venture capital but reported that he did not manage to raise “a penny.” He cited the fact that “private sector risk capital wants to have return in the next 2 to 3 years” and that “[t]hose things that are 3 or 4 years out are very difficult to get funded” [(76), pp. 5, 18].
The failure to secure venture capital backing could be attributed to the fact that the stock market was not particularly interested in funding new firms during this time. Between 1970 and 1982, it was only reasonable to open initial public offerings for new companies during “six to eight quarters out of more than fifty” [(31), pp. 437–438]. The failure could also be viewed as an example of a network failure, as what Schrank and Whitford (77) call “network stillbirth.” Venture capital firms that were oriented toward high technology invested mainly in products that they were already familiar with (26). They made up a tight-knit group that tended to co-invest, particularly when making risky investments. If one firm did not choose to invest in a company, neither would others. Being excluded from this network meant that venture capital would not be available.
Bank loans were not a viable option for most entrepreneurs either. Smaller firms, such as Solenergy, found that banks were “were completely unfamiliar with photovoltaic technology, and were unwilling to spend the time necessary to understand its production and application” [(75), p. 13]. Equity funding was out of the question for all but a few firms with established parent companies or proven success in other industries. In 1978, Solarex was the largest terrestrial PV producer in the world but could not become listed on the stock market [(64), p. 193]. Without a close working relationship with entrepreneurs, investors could not assess the technology. As one representative of the investment community noted in 1979,There is not at the present time a continuous dissemination of accurate information to bankers, underwriters, stock brokers, and insurance companies concerning the current state and expected development of photovoltaic technology, markets and industrial segment structure. If somebody in my community wants that information, they must go search it out [(78), p. 15].
Financial constraints made small firms struggle to survive even at the height of government support for the industry during the Carter years. The problem was outlined in a 1979 MIT report [(75), p. 1]:Capital availability is not a problem in a well-functioning market. However, the market for photovoltaic cells is immature; in fact, the market for grid-connected photovoltaic applications… does not yet exist. Therefore, the capital markets cannot easily evaluate the credit-worthiness, the economic attractiveness of the variety of photovoltaic production processes, research programs, or end-use applications currently being developed. Only when photovoltaic technologies converge to a roughly standardized set of mass production methods and consumer applications will private capital markets perform their job of allocating financial resources to the photovoltaic industry.
The U.S. Department of Energy appears to have been unaware of the problem. In language reminiscent of the “efficient market hypothesis,” the agency describes capital markets as “among the more ‘perfect’ markets in existence” [(78), p. 65].
Solarex was an exception. It was the only independent firm that managed to bridge the financing gap without ceding control to an oil company. It did so in several ways—first, by attracting a sympathetic angel investor who explicitly likened his investment to a “charitable donation” [(64), p. 20]. This, in turn, convinced the First American Bank of Maryland to grant the firm a credit line. Solarex also formed a joint venture with French firm France Photon, giving it access to African markets, and obtained equity funding from Holec, a Dutch electrical company, and Leroy-Somer, a French electric power–generating company. The oil company Amoco also invested in the firm, without taking control over it, which gave Solarex’s bank the confidence to expand its credit line. When the bank finally withdrew their credit line in 1983, Varadi and Lindmayer saw no other option but to cede strategic control of the firm and let it become a wholly owned subsidiary of Amoco [(72), p. 116].
Phase 2: Conglomerates take over
Beyond a lack of information, small firms had difficulties securing finance because investors knew that huge conglomerates were in competition with them [(72), p. 80]. In other words, the opportunities of challengers were heavily circumscribed by incumbents. Banks wondered “how a small business could compete with subsidiaries of Mobil, Exxon, Shell, Arco, Motorola, and Texas Instruments” [(75), p. 13]. Small firms that did acquire finance could mainly cater to small specialty markets. For example, the founder of Solec consciously avoided investing in research, expensive materials, and direct competition with oil companies [(79), p. 30]. The American PV industry became bifurcated, consisting of one segment that focused only on long-term research and another on manufacturing [(69), pp. 122–124]. Only independent firms backed by oil money could do both. The divided industry could not put up a united front in their efforts to influence energy policy. Strapped for cash, several small PV firms survived by selling their technology to Japanese competitors [(74); (76), p. 12].
Capital constraints for small firms were so great that, at the end of the 1970s, it was considered probable that “the mass-production photovoltaic industry will consist entirely of wholly-owned subsidiaries of (large) conglomerates” [(75), p. 28]. Paul Maycock, who ran the U.S. Department of Energy’s PV program, assumed in 1980 that the PV market would resemble the oligopolistic auto industry rather than the competitive electronics industry: “In the end,” he predicted, “we are going to have four companies, as in the automobile industry” (80).
The Federal Reserve appears to have exacerbated the problem with its monetarist experiment of extraordinary high interest rates in 1979 to 1982. Beyond raising the price of credit, the policy harmed the PV industry by attracting foreign capital flows that pushed up the value of the dollar, hurting exports, which accounted for 70% of PV sales at the time [(76), p. 53; (81), p. 12].
Most independent entrepreneurs were compelled to sell their firms to large conglomerates, worsening the situation for the few independents that remained. Conglomerates were reportedly “cross-subsidizing below-profit production in order to secure a market share in the longer run” [(82), p. 24]. By handing over operations to conglomerates, entrepreneurs ceded strategic control over their enterprises. Production decisions would, from then on, be made in central headquarters, far away from the shop floor, not on the basis of deep knowledge of manufacturing but on the quantitative measure of return on investment [(75), pp. 15–18].
When large corporations took over, so did the large-scale vision they favored. Elliot Berman’s small-scale vision for SPC clashed with Exxon’s, and when he left in 1975, the firm lost its leadership in building niche markets [(64), pp. 110, 129]. Solarex had catered to niche markets during the 1970s, but after it became a subsidiary of Amoco, the focus began shifting more toward the “big picture” goal of reaching “grid parity” with other forms of conventional energy production [(64), p. 187]. For oil majors to make a satisfactory return on their investment, they had to break through into the grid-connected utility electricity market. As one observer of Arco put it, “building solar-powered water pumps for Egyptian farmers was not Arco’s idea of a big market” (74).
The American PV industry was greatly affected by changes in corporate structure and strategy from the late 1960s to the 1980s. In the late 1960s, a new clique of financially oriented managers came to dominate American corporate governance (52). Their conception of control was to manage the corporation like an investment portfolio, buying and selling firms in other lines of business. As Espeland and Hirsch [(83), p. 78] describe them, “[t]hey were more financiers than managers, concerned with deal-making more than with the day-to-day operations of the companies they bought.” Most American corporations evolved into financial conglomerates, managing their subsidiaries from central headquarters with an arm’s length approach. Financial conglomerates tended to be “quite ‘thin’ at the top,” their administrative structure “fashioned simply to watch over and allocate capital among a portfolio of businesses, there being no central research and development or central staff-coordinating offices” [(84), p. 23]. Tacit information about production was transposed to formal information as decision-making moved from the shop floor to managers relying on quantitative measures such as return on investment (85). As conglomerates expanded into ever more diverse product lines, organizational integration eroded and strategic control moved out of the hands of personnel with intimate knowledge about production into the hands of financial managers in central headquarters.
Bill Yerkes of STI described his firm’s parent company Arco as a “bumbling behemoth” with no knowledge of PV or even of manufacturing in general [(72), pp. 80–84]. Against Yerkes’s protests, the company abandoned research in cadmium telluride and switched to amorphous silicon, resulting in a defective product that had to be withdrawn from the market twice. Despite its $200 million investment, Arco did not manage to turn a profit. Anticipating an expiration of tax credits, Arco rushed to construct the world’s largest PV plant without properly vetting the technology. Completed in 1985, it was never used. Similar problems plagued other conglomerates. RCA had pioneered thin-film solar technology but lacked the managerial resources to commercialize it and sold it instead to competing Japanese firms [(86), pp. 156–158]. It soon gave them their competitive edge in the market for solar calculators. Although conglomerates provided the PV industry with financial commitment through cross-subsidization, they lacked the other two social conditions of the innovative enterprise: strategic control and organizational integration. In the 1980s, financial commitment would erode as well.
Phase 3: Conglomerates are dismantled
While the American financial conglomerates of the 1970s were inept at developing PV, the situation worsened even more during the 1980s when the conglomerates were taken apart. The American corporation experienced a deep crisis in the 1970s to a large extent because of Japanese competition. In the 1980s, the strategy of unrelated diversification was delegitimized, and a new conception of control was instituted, continuing the trend toward increasing financialization. The rise of shareholder value and a concomitant restructuring of the American corporate landscape made corporations reverse their previous move toward diversification (87, 88). Cross-subsidization of diverse product lines was discontinued (89), causing a loss of financial commitment to PV technology. Deregulation and new debt instruments made it possible for corporate raiders to launch hostile takeovers or “greenmail” companies for cash. The already vulnerable PV industry became a victim of the upheaval. In the 1980s, “[s]olar companies in the United States became pawns in the market for corporate control” [(79), p. 36].
General Electric (GE) epitomized the new corporate philosophy, leading the way in shareholder value maximization under its new chief executive officer (CEO) Jack Welch. Shortly before he took over in April 1981, GE had made plans to expand its solar operation (90). The company had built one plant in 1980 and was planning to build another one in 1984. It also offered to buy the small firm Solec. When Welch took over, he trimmed the organization, refocused the firm, and launched hostile takeovers against other companies (91). He declared that GE was exiting all industries where it was not number one or number two, and solar energy was not one of them.
One of the victims of GE’s takeover bids was RCA. The company’s flawed diversification strategy in the 1970s had left it deep in debt, and the early 1980s saw the company desperately struggling to cut costs while “fending off a swarm of corporate raiders” (92). A new CEO refocused the firm on its core competency, selling off its solar division to Solarex, which subsequently became a subsidiary of Amoco (93).
The oil industry was particularly hard-hit by corporate raiders, who forced firms to restructure, shed unrelated businesses, and focus on the core competency (94, 95). Exxon had grown to immense size during the oil boom. Once oil prices declined, shareholders put pressure on the company to shed assets (96). The company sold its solar division, sending a signal to Wall Street that solar was “in the dog house” (97). Philips Petroleum had formed joint ventures with two solar firms in the early 1980s: AeroChem and Acurex. In 1985, corporate raiders set their sights on the firm, compelling it to go deep into debt to buy back stock. To repay the debt, the company sold assets, among them its solar positions. A company representative told the press that it could not afford the “luxury” of investing in alternative energy in the current environment (98).
Standard Oil of Ohio (Sohio) partnered with the innovative PV firm Energy Conversion Devices (ECD) to develop amorphous silicon technology (99). In the mid-1980s, the parent company British Petroleum grew dissatisfied with the firm, whose unprofitable exploration and diversification strategies depressed the stock price. A new CEO was sent in to restructure the firm to maximize shareholder value (100). Shortly thereafter, the firm sold off its stake in ECD, which instead partnered with Japanese firm Canon (101, 102).
The founders of Solarex also lost strategic control of their operation. The parent company Amoco had initially allowed them autonomy to continue to cater to small markets, but this changed in the mid-1980s. A new financially oriented management shifted focus and “eliminated everything that was not related to the ‘core business,’” including “the entire consumer business, catalogs, and stores” [(64), p. 187]. In the 1990s, the division survived through fraudulent tactics used by its partner firm Enron before it was merged into BP Solar (103).
Arco also experienced a shift in direction in the mid-1980s, when shareholder-oriented management was brought in to cut costs (93). Fearing a hostile takeover, the company spent billions of dollars buying back its own shares and divested from nonstrategic assets. In line with Wall Street practice, it refocused the company on its core competence, carbohydrates (104). Arco solar, which was the biggest PV firm in the world at the time, was sold to the German company Siemens. Energy analyst Philip K. Verleger Jr. at Charles River Associates explained the move by saying that American firms were “too tied up in short-term profits” to make the commitment necessary to make PV economically viable. As the New York Times summarized his argument, “[a] publically held company that invested heavily in solar technology would probably become the target of a corporate raider who would argue that shareholders’ money would get quicker profits elsewhere” (105).
Comparison with Japan
In 1978, American firms held 95% of the global market share; in 1984, it had declined to 55% [(106), p. 69]. The shift was mainly caused by Japanese competitors, who were integrating solar cells with consumer electronics such as calculators and watches. Building on these capabilities, Japanese firms later lobbied the state to provide residential subsidies, massively increasing the size of the industry (107). By the early 2000s, almost half of the world’s solar panels were manufactured by Japanese firms.
One of the most consequential developments behind the declining competitiveness of American PV took place outside the PV industry. In the 1970s, Japanese firms made inroads into industries related to PV, conquering almost half of the global semiconductor market and wiping out large parts of the American consumer electronics industry (108). These firms viewed PV as a complementary investment to their existing capabilities, where they could plow some of their retained earnings (107).
Japanese electronics firms’ main competitive advantage was financial commitment, secured through close ties with banks (109, 110). The Japanese postwar financial system was specifically designed to encourage investment in productive instead of speculative activity, partly inspired by the economic theory of Joseph Schumpeter (111). Banks provided firms with “dedicated capital” available for “long periods of time, without regard to short-term returns” [(112), p. 250]. Although Japanese banks turned highly speculative in the 1980s, corporate finance was largely insulated from these pressures by blocs of stable shareholders (113). Perhaps even more important than access to reliable credit was retained earnings and Japanese managers’ ability to exercise strategic control over them without regarding to shareholders’ interests. Managers were freed from “the restrictions of short-term perspectives” to set “long-term goals” [(114), p. 175]. Because of the institutional arrangement of cross-shareholding, in which firms held each other’s shares for the long term, Japan did not experience a “shareholder revolution” as the United States. Instead of managers being compelled to act like shareholders, institutional arrangements in Japan compelled shareholders to act like managers [(115), p. 227]. Crucially, Japanese PV producers were not subject to the “market for corporate control.” Beyond protecting against hostile takeovers, cross-shareholding meant that Japanese managers were “under less compulsion to sustain high quarterly profits than their U.S. counterparts, and therefore freer to focus on long-term expansion of market share” [(116), p. 44].
Last, and partly related to these events, a key strength of Japanese firms was the organizational integration of workers in the innovation process. American firms were segmented between white collar and blue collar workers [(56), part 1]. In Japan, (male) blue collar workers were integrated into the innovation process. Iwata (114) argues that the elimination of shareholder control after the Asia-Pacific War turned the Japanese enterprise into a “unified body of employees.” Lifetime employment turned the worker from “an external seller of his labor” to a “corporatist who shares the responsibilities of management” [(114), p. 176]. At Kyocera, one of the top Japanese PV producers, workers were organized in self-managing teams known as “amoebas.” According to Florida and Kenney [(117), pp. 158–159], this organization was a mechanism for “generating internal, self-imposed discipline, devolving manager responsibility to the shop floor, and motivating workers to work harder,” thereby “harnessing workers’ knowledge and collective problem-solving capabilities for the enterprise.”
In summary, Japanese institutional arrangements—bank financing, cross-shareholding, enterprise unions, and lifetime employment—aligned the interests of financial capital, production capital, and labor in a manner that allowed them to maintain the social conditions of innovation. Consequently, Japanese firms drove American competitors out of the electronics and PV markets. They also avoided the corporate upheaval that afflicted their American rivals—a restructuring that, to a large extent, was caused by Japanese competition in the first place.
DISCUSSION
This case study has revealed how the tension between productive and financial capital obstructed the development of the American PV industry. The American industry was greatly affected by changes to corporate governance brought by the trend toward increased financial dominance in the 1970s and 1980s: first, through conglomeration, in which corporations became governed as a diversified portfolios of assets to be bought and sold like stocks, and second, through its subsequent reversal in the 1980s, when financial deregulation allowed corporate raiders to break up the conglomerates, changing corporate governance in the process. The initial involvement of large financial conglomerates was ambiguous because they provided needed financial support but steered the industry away from existing markets toward a large-scale utility market that never emerged. By focusing almost exclusively on creating a future market for centralized energy generation, American firms missed the opportunity to develop the small off-grid and consumer electronics markets that were already available. There was an alternative path that was not taken toward decentralized solar energy, which would not have to compete with conventional sources. We know this because that is how the industry developed in Japan, where solar cells were applied mainly for off-grid use and consumer electronics, allowing the technology to mature gradually without much reliance on subsidies or record-level energy prices. This article demonstrates that the main reason this path was not taken in the United States was a disconnect between industry and finance.
The entrepreneurs who had the deepest knowledge of the technology and the markets where it would be cost-effective lacked connections to the financial sphere. Consequently, most of them succumbed to large financial conglomerates, which were inefficiently governed by arm’s length relations from central headquarters at first and by even more distant financial markets later. This made entry possible for Japanese firms, whose institutional and financial arrangements insulated them from financial constraints and destructive conflicts between shareholders and managers. The absence of financial control also allowed greater integration of workers in the innovation process.
The agents of productive and financial capital cooperated fruitfully in the Japanese PV industry but failed to do so in the United States. The failure represents an expression of an inherent tension between the entrepreneurial and financial components of innovation. Recognizing this tension is crucial to understand the challenge of industrial transformation required to avoid catastrophic climate change. It cannot be assumed that, by correcting market failure by putting a price on carbon, the financial system will adjust passively. Although a carbon tax would make low-carbon technology in general more competitive, there is no way of knowing which specific future technologies will succeed. The only sure thing is that most new technologies will fail. Innovation is always uncertain and wise to avoid if there are easier ways to make money off of speculation. Keynes noted that the ever-present tendency toward financialization calls for a substantial share of public investment. This is particularly true of extra-market goals, such as the mitigation of climate. Because, in Keynes’ theory, resources are almost never fully used, public investment does not compete with private investment. The importance of specific knowledge in financing decisions means that these public entities should have very specialized domains of operation. Perhaps, the recently expanded role of central banks in economic governance could play a role in developing low-carbon technology, a topic worthy of future investigation.
Industrial policy is necessary to guide the transition to a postcarbon future, but it works best when it allows decentralized credit creation for technological development by private entrepreneurs and financiers. This requires a financial system that promotes credit creation for productive rather than speculative activity. A political strategy to bring productive and financial capital together is needed. It is necessary to close off easy ways of making money off money, such as speculation and stock buybacks. This article has examined ways in which financialization impedes the development of low-carbon industries. It has not examined ways in which financialization may aid it. This interesting issue needs to be addressed in further studies.
MATERIALS AND METHODS
This project used a historical-comparative case study approach, which allowed causation to be studied in historical time (118, 119). It focused on the relationship between entrepreneurs and financiers in small and large American solar firms between 1970 and 1989, contrasting the American solar industry with the situation in Japan. Japan was chosen as a reference because it has an economy of roughly half the size of the United States while managing to foster a PV industry with a global market share many times the American share (9). The method required a broad overview of developments in the wider institutional context surrounding the firms under study. Because accounts differ, as they always do in social science, extensive referencing of second-hand sources was necessary.
The study of the PV industry deliberately utilized a variety of bibliographic sources, including business press articles, governmental reports, congressional hearings, academic articles and books, and biographical accounts by involved entrepreneurs. Searches for newspaper articles referencing solar energy or PV cells, as well as the names of the firms involved in the industry, were made in databases ProQuest and LexisNexis between the years 1970 and 1990, along with analysis of annual reports of the large corporations involved.
Acknowledgments
I would like to thank my colleagues at the Swedish Foundation for Strategic Environmental Research (MISTRA) Center for Sustainable Markets (MISUM) at the Stockholm School of Economics for commenting on the article. In particular, I would like to thank Ö. Sjöberg for guidance and the patience to read and comment on multiple drafts. I would also like to thank B. Callegari for providing detailed and insightful comments. Funding: Finance has been provided by MISTRA. Competing interests: The author declares that he has no competing interests. Data and materials availability: All data needed to evaluate the conclusions in the paper are present in the paper. Additional data related to this paper may be requested from the author.
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Sci AdvSci AdvSciAdvadvancesScience Advances2375-2548American Association for the Advancement of Science 160076210.1126/sciadv.1600762Research ArticleResearch ArticlesSciAdv r-articlesEnvironmental StudiesDominant 100,000-year precipitation cyclicity in a late Miocene lake from northeast Tibet Nie Junsheng http://orcid.org/0000-0002-0350-200112*Garzione Carmala http://orcid.org/0000-0002-0350-20012Su Qingda 1Liu Qingsong http://orcid.org/0000-0001-9472-490434Zhang Rui 1Heslop David 5Necula Cristian 6Zhang Shihong 7Song Yougui 8Luo Zeng http://orcid.org/0000-0001-9982-926211 Key Laboratory of Western China’s Environmental System (Ministry of Education), College of Earth and Environmental Sciences, Lanzhou University, Lanzhou, Gansu 730000, China.2 Department of Earth and Environmental Sciences, University of Rochester, Rochester, NY 14627, USA.3 Department of Marine Science and Technology, South University of Science and Technology of China, Shenzhen 518055, China.4 Laboratory for Marine Geology, National Oceanography Laboratory, Qingdao 266061, China.5 Research School of Earth Sciences, Australian National University, Canberra, Australian Capital Territory 0200, Australia.6 Faculty of Physics, Paleomagnetic Laboratory, University of Bucharest, Nicolae Balcescu, Sector 1, 010041 Bucharest, Romania.7 State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Beijing 100083, China.8 State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, P.O. Box 17, Xi’an 710075, China.* Corresponding author. Email: jnie@lzu.edu.cn3 2017 29 3 2017 3 3 e160076210 4 2016 10 2 2017 Copyright © 2017, The Authors2017The AuthorsThis is an open-access article distributed under the terms of the Creative Commons Attribution-NonCommercial license, which permits use, distribution, and reproduction in any medium, so long as the resultant use is not for commercial advantage and provided the original work is properly cited.Paleoclimatic records reveal >6–million year earlier onset of dominant 100–thousand year eccentricity cycles.
East Asian summer monsoon (EASM) precipitation received by northern China over the past 800 thousand years (ky) is characterized by dominant 100-ky periodicity, mainly attributed to CO2 and Northern Hemisphere insolation–driven ice sheet forcing. We established an EASM record in the Late Miocene from lacustrine sediments in the Qaidam Basin, northern China, which appears to exhibit a dominant 100-ky periodicity similar to the EASM records during the Late Quaternary. Because evidence suggests that partial or ephemeral ice existed in the Northern Hemisphere during the Late Miocene, we attribute the 100-ky cycles to CO2 and Southern Hemisphere insolation–driven Antarctic ice sheet forcing. This indicates a >6–million year earlier onset of the dominant 100-ky Asian monsoon and, likely, glacial and CO2 cycles and may indicate dominant forcing of Northern Hemisphere climate by CO2 and Southern Hemisphere ice sheets in a warm world.
Keywords
East Asian monsoonTibetan Plateauice sheetseccentricityorbital forcingAntarcticahttp://dx.doi.org/10.13039/501100002855Ministry of Science and Technology of the People’s Republic of ChinaID0EY2CI126042013CB956400Nie Junsheng http://dx.doi.org/10.13039/100000001National Science FoundationID0EZADI126051545859Garzione Carmala CopyeditorFlorcloven Cruz
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INTRODUCTION
The tenet of the Milankovitch theory is that Northern Hemisphere summer insolation, controlled by Earth’s orbital parameters {precession [~23 thousand years (ky)], obliquity (~41 ky), and eccentricity (~100 and ~400 ky)}, drives ice sheet size variations (1). However, the observed dominant 100-ky ice age cycles in paleoclimate records during the Late Quaternary challenge this theory because the insolation variations associated with Earth’s orbital eccentricity are much weaker than those associated with precession and obliquity (2–6). The paleoclimate community has coined the term “the glacial 100-ky problem” to describe the perplexing dominant 100-ky climatic periodicity during the past 800 ky. Although glacial cycles during the Pliocene and the Early Quaternary do not show dominant 100-ky cycles, but instead show dominant 41-ky cycles, it is unknown whether dominant 100-ky ice sheet cycles existed during the Late Miocene when Earth was characterized by marked Antarctic ice sheet variations (7, 8). This lack of knowledge of the tempo of glaciations in deep time is caused by a lack of Late Miocene ice volume records that are not conflated with deep-ocean water temperature bias (9).
Terrestrial ice volume variation and atmospheric CO2 concentration covary, and they are two dominant factors controlling the East Asian summer monsoon (EASM) precipitation in northern China during the Late Quaternary (10–12). Therefore, EASM variations at orbital time scales could be potentially used to determine fluctuating patterns of the ice sheets and CO2 during the Late Miocene. Because available Late Miocene atmospheric CO2 records cannot yet resolve orbital time scale CO2 variations (13–15) and the benthic oxygen isotope records include a mixed signal of ice volume and deep-ocean water temperature, often decoupled from each other (9), independent constraints from the Late Miocene EASM record could be crucial for determining the nature of the dominant 100-ky ice age cycles.
The northwestern limit of the modern EASM precipitation is close to the southeast margin of the Qaidam Basin (Fig. 1), and previous research has suggested that EASM precipitation likely penetrated further inland during the mid-Holocene (12). The Late Miocene was characterized by even warmer climate (7, 16, 17). Therefore, the Qaidam Basin is a good place to record EASM variability, in particular the migration of northwestern margin of influence of EASM precipitation, and shed new light on CO2 and Antarctica ice sheet variations during the Late Miocene. Following the recommendation by Wang et al. (18), a stronger EASM at orbital and tectonic time scales is defined here as increased monsoon precipitation in northern China, associated with a northwestward shift of the East Asian subtropical frontal system (also called Meiyu front).
Fig. 1 Map of the study sites and atmospheric circulation pattern.
Black dashed line depicts the Asian summer monsoon fringes at present (84). The white dashed circle represents the Siberian High in January. HTTL, Huaitoutala; LX, Linxia; JY, Jingyuan; QA, Qinan; Q, Qaidam Basin; CLP, Chinese Loess Plateau.
RESULTS
In the eastern part of the Qaidam Basin, Late Miocene open lacustrine sediments are exposed near the Huaitoutala (HTTL) village (19). The lack of positive correlation between oxygen and carbon isotopic compositions of bulk carbonate supports the sedimentary interpretation of an open lacustrine depositional environment for these strata (fig. S1). We performed paleomagnetic sampling of this section to establish a high-resolution age model (Fig. 2) and then reconstructed variability of the EASM during this time interval on the basis of a recently developed magnetic monsoon proxy (20) that is sensitive to monsoon precipitation, but not to temperature (Fig. 3).
Fig. 2 Age model and lithology (19) of Late Miocene HTTL section in the Qaidam Basin.
C3Br.1n and the reversed interval between C3Br.2n and C4n.1n are each constrained by a single data point. The bottom boundary of C4r.1n in the observed polarity has multiple possibilities. Therefore, these five reversal ages (which correspond to the dashed lines) are not used to establish the age model. VGP, virtual geomagnetic polarity (22); m, mudstone; f, fine sandstone.
Fig. 3 χfd/HIRM versus annual mean precipitation and temperature for surface soil samples across the CLP.
The annual mean temperature (AMT) and the annual mean precipitation (AMP) data are from meteorological stations on the CLP. The sample sites are the same as those in the study by Nie et al. (85).
Age model
A preliminary age model of the section that is based on 2- to 5-m resolution magnetostratigraphy and multiple fauna layers was established by Fang et al. (21). Our higher-resolution paleomagnetic resampling and analysis (0.5 to 1 m) of the middle portion of the section allowed us to find all reversed polarities within the previous age model framework, improving the robustness of the age model (Fig. 2). For example, C3Bn, C3Br.1n, C4Ar.2n, and C5n.1n were not recognized in the age model of Fang et al. (21) (Fig. 2). In addition, the age model by Fang et al. (21) only recognized a portion of C3Br.2n and C4n.1n, resulting in a longer C3Br.2n than C4n.1n, opposite to the pattern in the geomagnetic polarity time scale (GPTS). All of these deficiencies are now fixed in our higher-resolution results. This greater age model precision is essential for spectral analysis. We found 12 normal polarities (N1 to N12), which we correlate to the 12 normal polarities between 10 and 6 Ma (million years ago) in the GPTS (22). We established the age model by piecewise linear interpolation using the reversal ages (table S1).
The northern China precipitation record
The new magnetic monsoon proxy χfd/HIRM (frequency-dependent magnetic susceptibility/hard isothermal remanent magnetization) reflects the ratio of fine nanometer-scale ferrimagnets (magnetite and maghemite; measured by χfd) over hematite (measured by HIRM) (see Materials and Methods). Magnetic remanence unmixing analysis reveals the common existence of two types of magnetic minerals with coercivity peaks of 26 and 330 mT, which we infer correspond to fine magnetite/maghemite and hematite, respectively (fig. S2). These fine magnetic minerals are produced during weathering processes, but production of hematite requires less precipitation in comparison with fine ferrimagnetic grains (23, 24). Thus, high χfd/HIRM indicates strong EASM precipitation and more intense diagenetic weathering.
The χfd/HIRM record suggests intensified EASM precipitation during ~8.5 to 7 Ma (Fig. 4D and data set S1). This can be further verified by both the chlorite/(goethite + hematite) ratio and the halite content data from the same section (see Materials and Methods and fig. S3). Chlorite is a product of physical erosion, whereas goethite and hematite are largely produced by chemical weathering (25). Thus, their ratio can reflect weathering intensity (25). Halite represents later-stage evaporation of a lake (26); thus, here, higher halite content is interpreted to indicate a drier climate. These proxy records are all consistent with a phase of wet climate during 8.5 to 7 Ma (Fig. 4, E and F, and data set S1).
Fig. 4 Paleoenvironmental records during the Late Miocene.
(A) Ocean Drilling Program (ODP) site 722 n-alkane C31 carbon isotope record (48). (B) Qinan loess magnetic susceptibility (χ) record (86). (C) Linxia lacustrine sediment oxygen isotope record (27). (D to G) Qaidam Basin HTTL section χfd/HIRM, halite content, chlorite/(hematite + goethite) [C/(H+G)] ratio, and mean grain size record. (H) Benthic oxygen isotope record from ODP Site 982, North Atlantic Ocean (50). We did not include several negative χfd/HIRM and unrealistically high χfd/HIRM and C/(H+G) values from the Qaidam records. To promote readability, wetting corresponds to the right-hand direction for the Asian monsoon records. The blue bar in (G) shows the interval that has relatively constant grain size without flooding events for over 400 ky after 8.5 Ma.
Other East Asia archives also record this phase of wetting. In Linxia (27), the oxygen isotope values of lacustrine sediments decreased after ~8.5 Ma, interpreted as wetter climate (Fig. 4C). On the western Chinese Loess Plateau (CLP) (28), Qinan magnetic susceptibility (χ) increased during ~8.5 to 7.2 My (Fig. 4B), indicating wetter climate. Thus, there is consistency between independent methods and locations in East Asia for greater precipitation approximately coeval with the Qaidam record.
DISCUSSION
Million-year time scale variations of EASM
EASM precipitation pattern in China is determined mainly by the jet stream’s interaction with the Tibetan Plateau (mechanical role) (29) and by heating of the plateau (thermal role) (30, 31). The Tibetan Plateau interacts with the jet stream to steer the subtropical frontal system east of the Tibetan Plateau, promoting precipitation in China (29). Intensified heating associated with a high plateau can amplify the low-pressure system on the Tibetan Plateau, amplifying sea-land pressure contrast and causing additional precipitation in China (30, 31). When the (northern) Tibetan Plateau is low, these effects are weakened, resulting in decreased EASM precipitation (31, 32). Therefore, upward and/or outward growth of the marginal portions of the Tibetan Plateau will result in penetration further inland of the EASM precipitation, as was recently demonstrated in model simulations (33). Sedimentological and thermochronology evidence reveals that the northeastern Tibetan Plateau experienced a phase of upward and/or outward growth during the Late Miocene (34, 35). For example, low-temperature thermochronology data reveal that rapid exhumation occurred in the Liupan Shan (36) and the north Qilian Shan (37) areas, and sedimentary accumulation rates (38) and provenance data (39) in the Guide Basin reveal rapid exhumation of the Laji Shan during the Late Miocene. Therefore, we predict a coeval increase in inland Asia precipitation if the northern margin of the northeastern Tibetan Plateau rapidly propagated into inland Asia in the Late Miocene. However, this inference is in contradiction with the widely held idea of Late Miocene Asian drying, which is based on increased dust accumulation in the North Pacific Ocean (40) and the onset of loess accumulation on the central CLP around 8 Ma (41, 42). Recent studies reveal that CLP dust does not necessarily come from deserts and that increased dust accumulation does not necessarily indicate inland Asian aridification (43–46). This is because tectonic deformation can produce dust for wind to entrain and transport downwind (44, 47). Specifically, the older loess (~8 Ma) on the central CLP has a relatively large zircon grain size compared to the typical loess, which has been attributed to tectonic deformation–produced dust associated with growth of the Liupan Mountains and wind erosion in the Qaidam Basin (44, 46). Furthermore, dry riverbeds have recently been recognized as important dust sources for the CLP and, by inference, for the downwind North Pacific Ocean (43, 45, 46).
The records we compile and present here demonstrate that, contrary to common thinking, northern China has become wetter since ~8.5 Ma. The South Asian records also reveal a phase of wetting during ~8.5 to 7 Ma. The C4 plant expansion trend, initiating from at least 10 Ma, shows a reversal pattern (Fig. 4A) as recorded by leaf wax carbon isotope in the Indian Ocean sediments (48); higher plant leaf waxes mainly came from regions around Pakistan, Iran, Afghanistan, and the Arabian Peninsula. Together, the approximate synchroneity in both the East Asian and the South Asian records suggests that the growth of northeastern Tibet during the Late Miocene might have had significant effects on climate both north and south of the Tibetan Plateau (Fig. 1). On the other hand, if the entire plateau or additional margins of the Tibetan Plateau experienced a phase of rapid outward and upward growth at ~8.5 Ma, as proposed by some researchers (49), this may explain the synchronous climatic wetting both north and south of the Tibetan Plateau. Regardless of the scale of the growth of the Tibetan Plateau (northeastern growth versus upward growth), it is noteworthy that oxygen isotopic compositions of benthic foraminifera at Ocean Drilling Program (ODP) site 982 (50) reveal a phase of climatic cooling/ice sheet growth at ~8.5 Ma (Fig. 4H), suggesting that atmospheric CO2 concentrations also declined. It is plausible that Late Miocene expansion of the Tibetan Plateau has played a role in global climate cooling, perhaps through silicate weathering (51) and increased carbon burial (52).
Ice-rafted debris started to reach ODP site 918, North Atlantic Ocean, starting from ~7 Ma (53), indicating that ice sheets in Greenland had expanded to the sea by then. We attribute weakening of the EASM after 7 Ma to the initiation of Northern Hemisphere glaciations (7) and decreased Northern Hemisphere sea surface temperature (17, 48, 54), which caused a southward shift of the dry limb of the Hadley circulation.
Although we outline a plausible mechanism for million-year time scale EASM precipitation variations during the Late Miocene, other possibilities exist. For example, some studies (55–58) suggest Eocene establishing of the northern Tibetan Plateau. If this is the case, the reason for the observed million-year time scale EASM variations needs further research. Furthermore, some evidence suggests that Northern Hemisphere land has at least ephemeral ice sheets before 7 Ma (59, 60). However, the sensitivity of the EASM to small-scale Northern Hemisphere ice sheet size variation is unknown, stimulating further research.
Orbital time scale variations of monsoon and ice volume
The χfd/HIRM record shows cyclicity, especially between 8.5 and 7 Ma when the record shows higher values than before and after. Spectral analysis of the environmental magnetic data reveals that 100-ky eccentricity cycles have the strongest signal (Figs. 4 and 5). Model simulation suggests that Tibetan uplift can amplify the EASM’s sensitivity to insolation forcing because of its thermal role on precipitation (31, 32). Several lines of geological evidence (36–39) suggest a phase of northeastward or upward growth of the Tibetan Plateau during the Late Miocene, which can explain the enlarged climatic fluctuation amplitude observed here (Fig. 4). The HTTL grain size record (Fig. 4G) shows that during ~8.18 to 7.78 Ma, there is a 400-ky-long interval where the sediment grain size is relatively uniform, indicating non–flood-transported coarse grains, but in the other intervals after 8.5 Ma, grain size pulses are associated with periodic flooding. Therefore, we compared the χfd/HIRM record during 8.18 to 7.78 Ma with the loess χ record on the northwestern CLP during the past ~400 ky (10). The two records show marked similarities in both time and frequency domains, with the 100-ky cycle as the dominant period (Fig. 6). Similar to the Late Quaternary, the Late Miocene 100-ky cycles also consist of bundling of several precession and/or obliquity cycles (6, 61, 62), suggesting similar forcing mechanisms.
Fig. 5 The wavelet transform (87) (left) and the power spectrum (right) of the χfd/HIRM record from the Qaidam Basin.
The color scale indicates power, which is scaled to percent total power, and the hatched areas illustrate the cone of influence and, hence, the edge effects of the transform. We note that warm color indicates larger power. The 400-, 100-, 40-, and 20-ky periodicities are labeled and indicated by the straight black lines. The black contour is the 20% significance level, using a red noise background spectrum.
Fig. 6 A comparison of the EASM variations during the Late Miocene and the Late Quaternary for a time period of ~400 ky.
(A) The χfd/HIRM record from the Qaidam Basin during 8.18 to 7.78 Ma. (B) The χ record from Jingyuan in the northwestern CLP during the past ~400 ky (10). (C) The normalized χ record from the central CLP during the past ~400 ky (63). (D to F) The power spectrum of (A) to (C) (solid lines) and the lower limit of their 80% significance interval (dashed lines). The power spectrum was generated using the AnalySeries 2.0.4 software (88). For comparison, the eccentricity data (pink curves; higher value is upward) (89) during 8.18 to 7.78 Ma and 0.4 to 0 Ma are also shown in (A) and (B), respectively
These precession and obliquity signals are not as clear in the central CLP record (63) as those in the northwestern CLP record (Fig. 6, C and F). We attribute this to low sediment accumulation rate and precipitation-driven postdepositional alteration of loess deposited in situ and the underlying loess on the central CLP, which caused signal smearing (64). This explanation is supported by sedimentological observation. For example, paleosol S1 (with a depositional age of ~0.1 Ma; Fig. 6) consists of three distinct dark-colored subpaleosol units interlayered with two light-colored subloess units for the northwestern CLP, but for the central CLP site, S1 is a dark layer without subloess layers (65). Thus, to accurately record variations of the EASM, sites with high sedimentation rates and little postdepositional alteration are preferred. The HTTL section, which is next to the northeastern edge of the EASM (Fig. 1), with about four times higher sedimentation rate during 10 to 6 Ma than the Quaternary loess from the central CLP, should provide a more reliable EASM intensity signal during the Late Miocene.
In theory, the 100-ky cycles would be intensified if the climatic record shows a muted response to the cold phase of insolation forcing; however, such a response will still show dominant variability at the 23-ky band (fig. S4). Our sampling resolution is ~3.6 ky for the interval from 8.5 to 7 Ma, which is high enough to resolve the 23-ky signal. The observation that the 23-ky signal is much weaker than the 100-ky signal suggests that the EASM’s muted response to the cold phase of insolation forcing is not the main reason for the observed dominant 100-ky cycles.
Because ephemeral ice existed in the Northern Hemisphere before 7 Ma, as is suggested by the ice rafting record of southeast Greenland (53), the dominant 100-ky cycles in our monsoon record could be attributed to Southern Hemisphere insolation–driven Antarctic ice sheet forcing. There are several ways that Antarctica ice sheet size variations could affect the monsoon. First, sea level variations associated with Antarctica ice sheet size variations during the Late Miocene would have caused periodic advance and retreat of the EASM northeastern edge, as observed in the Late Quaternary (10, 12). Second, tropical Pacific Ocean water evaporation will decrease during lower sea surface temperatures associated with colder glacial climate, which would cause additional retreat of the extent of EASM precipitation. On the basis of estimates from the South China Sea, moisture evaporation associated with surface seawater cooling decreased by 1/8 to 1/4 during the last glacial maximum in comparison with current China annual precipitation (66), which can cause a significant decrease of the EASM precipitation, especially near its northwestern extent. Third, research suggests that Antarctica ice sheet size variation was an important driving force affecting the orbital time scale Asian summer monsoon intensity via changing cross-equatorial pressure gradient and amount of latent heat release during the Pleistocene (67, 68).
During 7 to 1 Ma, ice sheet expansion and shrinking occurred in both hemispheres forced by local insolation, resulting in strengthened 41-ky obliquity cycles (69). In the Late Quaternary after ~1 Ma, the Antarctic ice sheets grew to be marine-based, and from then on, the Antarctic ice sheets ceased being controlled by local insolation but was instead controlled by eustatic sea level (69). When the Northern Hemisphere has larger ice sheets and sea level is low, Antarctic ice sheets also expanded over continental shelf area exposed by sea level fall; when sea level is high during interglacials, Antarctic ice sheets lose ice by rafting and calving of the margins of the ice sheets. Thus, global ice volume variations are mainly caused by ice sheet expansion and shrinking in the Northern Hemisphere after ~1 Ma (69), resulting in the reappearance of the dominant 100-ky cycles.
The published benthic oxygen isotope records during the Oligocene and the Early Miocene (7, 70) show strong 100-ky cycles, supporting the inference that the Antarctica ice sheet was fluctuating at a dominant 100-ky periodicity before the formation of Northern Hemisphere ice sheets after 7 Ma. Furthermore, a recent study (71) separated Antarctica ice volume variations from the Late Oligocene–Early Miocene benthic oxygen isotope record on the basis of inverse modeling, and the results show that the Antarctica ice sheets were dominated by 100-ky pacing, particularly during the termination phases of the major Antarctic glaciations, further supporting our inference.
Although this mechanism is plausible, we cannot exclude the fact that CO2 is an important forcing mechanism of EASM variability at orbital time scales. It could well be that CO2 covaried with Antarctica ice sheet fluctuation at orbital time scales, similar to the condition for the past 800 ky between CO2 and Northern Hemisphere ice sheets. Unfortunately, available CO2 records (13, 72) do not yet have the resolution to resolve orbital time scale variability.
In summary, we reveal that the northern China precipitation was fluctuating at a dominant 100-ky pace during the Late Miocene. Therefore, although the dominant 100-ky cycles during the Late Quaternary are considered anomalous by the paleoclimate community (2, 3), they appear to have been the dominant cycle at least 6 to 7 My earlier in the EASM and, likely, ice sheet records. Considering the recent discovery of the Eocene onset of the EASM (73–75) and strong pre-Miocene 100-ky cycles in the Antarctica ice sheet (7, 70) and Asian aridification records (76), it is likely that the dominant 100-ky eccentricity cycles exist in the pre-Miocene EASM records when data with enough resolution are available for this older interval.
If our model is correct, under future warming scenarios where the Greenland Ice Sheet markedly shrinks and the Antarctica ice sheet is land-based again, the 100-ky ice age and EASM cycles experienced during the past 800 ky will continue because of ice sheet expansion and shrinking in Antarctica caused by Southern Hemisphere summer insolation variations, which is opposite to Northern Hemisphere summer insolation variations.
MATERIALS AND METHODS
Paleomagnetism dating
Oriented cylindrical paleomagnetic samples were taken at intervals of 1 m from the middle portion of the HTTL section in August 2011 using a portable gasoline-powered drill, and loose samples were also taken from the same stratigraphic level for paleoenvironmental reconstruction purpose. This portion corresponds to the upper Shang Youshanshan and lower Shizigou formations, deposited in an open lacustrine environment (fig. S1) (19). The oriented samples were cut into a height of ~2 cm in the laboratory and thermally demagnetized and analyzed in the Paleomagnetism Laboratory in the Institute of Geology and Geophysics, Chinese Academy of Sciences, and in the Ministry of Education Key Laboratory of Western China’s Environmental Systems, Lanzhou University, China. Pilot samples and previous studies (21) show that viscous remanence is removed before 350°C and that hematite is an important remanence carrier. Therefore, we performed thermal demagnetization at temperatures 350°, 450°, 500°, 550°, 570°, 580°, 610°, 630°, 650°, and 670°C for the rest of the samples.
Environmental magnetism
Loose samples were crushed and packed in a box of 2 × 2 × 2 cm, and magnetic susceptibility (χ) was measured at 976 and 15,616 Hz, respectively, with Multi-Function Kappabridge in the Paleomagnetism Laboratory of the China University of Geosciences, Beijing, China. χfd is calculated as the χ difference measured at 976 and 15,616 Hz. Isothermal remanent magnetism (IRM) was imparted first at 1 T and then at −0.1 and −0.3 T. The HIRM (or hard IRM) is calculated as the sum of IRM1T and IRM−0.3T divided by 2. The L ratio is calculated as HIRM/[0.5 × (IRM1T + IRM−0.1T)] (77). If HIRM and L ratio are not correlated with each other, HIRM can be considered as a valid proxy for hematite content (77). Figure S5 shows that HIRM and L ratio are not correlated, supporting that HIRM can be used to indicate hematite content in this case.
Samples (104) were ground into powder before backfield measurements were performed on a PMC vibrating sample magnetometer (MicroMag 3900) at the Paleomagnetic Laboratory, University of Bucharest, Romania. Samples were first saturated at 1 T, and then the field was reversed and nonlinearly incremented until −1 T in 30 steps. To interpret backfield demagnetization curves, we used here the unmixing algorithm of Heslop and Dillon (78), as in the loess–red clay samples in the CLP (79). This method does not require prior knowledge of different components, but instead isolate different components based on an assemblage of measured samples. The estimation of the number of end members to be included in the unmixing model is based on the calculation of the coefficient of determination, R2, versus the number of end members through the principal component analysis.
X-ray diffraction patterns
The analyses were carried out on crushed samples using a Rigaku D/Max-2400 diffractometer with a Cu Kα (λ = 1.54056 Å) radiation operating at 40-kV voltage and 60-mA current in the School of Physical Science and Technology, Lanzhou University. The x-ray diffraction patterns were obtained at a scanning rate of 15°/min, with a step width in the 2θ scan of 0.02° in the range 3° to 80°. The intensity of each mineral was estimated from peak height.
Diffuse reflectance spectroscopy
Diffuse reflectance spectroscopy across the entire wavelength spectrum of visible light (400 to 700 nm) in a 0.5-nm step was performed using a Peking PUXI TU-1901 spectrophotometer equipped with a BaSO4-coated integrating sphere that is 58 mm in diameter (IS19-1, Purkinje General). Samples were previously powdered and pressed by hand into the circular holes of sample holders (thickness, 2.5 mm) at a pressure >500 kPa. The resulting mounts were self-supporting, thus allowing the holders to be vertically placed without the powder falling into the sphere. Following the measurements, the signals were unmixed using the nonnegative matrix factorization method (80). A three-component unmixing is the simplest model that provides a high-quality fit to the measured data and separates the unweathered mineral chlorite from the weathered minerals hematite and goethite (fig. S3). Then, a revised RCAT parameter (25) was calculated as chlorite/(hematite + goethite).
Grain size
The grain size of the powered samples was analyzed using a Malvern Mastersizer 2000 particle size analyzer, within the range of 2000 to 0.01 μm. Before analysis, samples were pretreated with hot hydrogen peroxide to remove organic matter and with hydrochloric acid to remove carbonate, following the standard procedure at the Lanzhou University.
Monsoon proxy explanation
The new magnetic monsoon proxy reflects the ratio of fine (nanometer-scale) ferrimagnetic (measured by frequency-dependant susceptibility, χfd) over hematite (measured by HIRM) grains produced during sediment erosion from source regions and transport until they were deposited within the lake. This process is rapid in the northeastern Qaidam basin and was caused by the active tectonics of the northeastern Tibetan Plateau during the Late Miocene. Provenance analysis (81) demonstrates that the sediment source for the studied section had always been the Qilian Shan and Nanshan Mountains to the northeast since the Early Miocene, which is within some tens of kilometers. Therefore, parent materials are relatively uniform. Previous works (20, 23, 82) reveal that diagenetic modification to rocks will produce nanometer-scale ferrimagnetic (maghemite and magnetite) and antiferrimagnetic (hematite and goethite) minerals, and production of ferrimagnetic materials requires more precipitation than hematite. A previous research (20) and our own calibration (Fig. 3) using surface soils on the CLP also reveal that their ratio is not sensitive to temperature variations. By assuming that there was no dissolution for magnetic materials after they were deposited in lake, their ratio can be used as a proxy for EASM intensity. Dissolution of magnetic minerals usually occurs under reduced conditions where oxygen is limited. However, open lacustrine settings (as suggested by scattered stable oxygen and carbon correlation plot; fig. S1) indicate that oxygen was not likely limited. The IRM unmixing result (fig. S2) provides direct support to this inference. The ubiquitous existence of the 26- and 330-mT component indicates that fine maghemite/magnetite and hematite grains did not dissolve (83). The 88-mT component corresponds to partially oxidized coarse magnetite grains (79), again indicating a generally oxidizing depositional environment. The consistency between the magnetic precipitation record with the evaporite mineralogy and chloride/(goethite + hematite) records (Fig. 4) further demonstrates that the magnetic precipitation record in the Qaidam Basin reliably records erosion and runoff, which we interpret as an EASM intensity signal during the Late Miocene.
Acknowledgments
Constructive comments by the associate editor K. Whipple and three reviewers significantly improved the manuscript. We thank L. Gong and M. Li for laboratory assistance and Q. Meng, Y. Miao, S. Ji, W. Peng, and K. He for field assistance. Funding: This work was funded by the national key research and development program of China (2016YFE0109500), the (973) National Basic Research Program of China (grant no. 2013CB956400), the Strategic Priority Research Program of the Chinese Academy of Sciences (grant no. XDB03020400), the National Natural Science Foundation of China (grant nos. 41422204, 41172329, and 41290253), and the U.S. NSF (grant no. 1545859). Author contributions: J.N. and Q.L. designed the experiments. Q.S., R.Z., C.N., and Z.L. performed the experiments. All authors analyzed the data. J.N. wrote the manuscript with help from the other authors. Competing interests: The authors declare that they have no competing interests. Data and materials availability: All data needed to evaluate the conclusions in the paper are present in the paper and/or the Supplementary Materials. Additional data related to this paper may be requested from the authors.
SUPPLEMENTARY MATERIALS
Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/3/3/e1600762/DC1
fig. S1. A comparison of oxygen and carbon isotope data of the HTTL section.
fig. S2. Unmixing of backfield IRM curves of the HTTL samples.
fig. S3. The smoothed end-member reflectance spectra (left) and its first derivative spectra (right) for the HTTL samples.
fig. S4. A comparison of power spectrum of full (lower) and truncated (upper) insolation for July at 35°N (73).
fig. S5. A comparison of HIRM and L ratio for the HTTL samples.
table S1. Age tie points used to establish the age model for the HTTL section.
data set S1. HTTL section paleoclimatic data in Fig. 4.
==== Refs
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Sci AdvSci AdvSciAdvadvancesScience Advances2375-2548American Association for the Advancement of Science 28435859160119110.1126/sciadv.1601191Research ArticleResearch ArticlesSciAdv r-articlesEarth SciencesThe frequency and extent of sub-ice phytoplankton blooms in the Arctic Ocean Horvat Christopher http://orcid.org/0000-0001-6512-03351*Jones David Rees http://orcid.org/0000-0001-8698-401X23Iams Sarah http://orcid.org/0000-0001-6255-50771Schroeder David http://orcid.org/0000-0002-7490-768X4Flocco Daniela http://orcid.org/0000-0002-0025-53594Feltham Daniel 41 Department of Applied Mathematics, School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA.2 Atmospheric, Oceanic and Planetary Physics, Department of Physics, Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU, U.K.3 Department of Earth Sciences, University of Oxford, South Parks Road, Oxford OX1 3AN, U.K.4 Centre for Polar Observation and Modelling, Department of Meteorology, University of Reading, Reading, U.K.* Corresponding author. Email: horvat@fas.harvard.edu3 2017 29 3 2017 3 3 e160119126 5 2016 10 2 2017 Copyright © 2017, The Authors2017The AuthorsThis is an open-access article distributed under the terms of the Creative Commons Attribution-NonCommercial license, which permits use, distribution, and reproduction in any medium, so long as the resultant use is not for commercial advantage and provided the original work is properly cited.Recent thinning and ponding of Arctic sea ice may have led to frequent, extensive phytoplankton blooms under sea ice.
In July 2011, the observation of a massive phytoplankton bloom underneath a sea ice–covered region of the Chukchi Sea shifted the scientific consensus that regions of the Arctic Ocean covered by sea ice were inhospitable to photosynthetic life. Although the impact of widespread phytoplankton blooms under sea ice on Arctic Ocean ecology and carbon fixation is potentially marked, the prevalence of these events in the modern Arctic and in the recent past is, to date, unknown. We investigate the timing, frequency, and evolution of these events over the past 30 years. Although sea ice strongly attenuates solar radiation, it has thinned significantly over the past 30 years. The thinner summertime Arctic sea ice is increasingly covered in melt ponds, which permit more light penetration than bare or snow-covered ice. Our model results indicate that the recent thinning of Arctic sea ice is the main cause of a marked increase in the prevalence of light conditions conducive to sub-ice blooms. We find that as little as 20 years ago, the conditions required for sub-ice blooms may have been uncommon, but their frequency has increased to the point that nearly 30% of the ice-covered Arctic Ocean in July permits sub-ice blooms. Recent climate change may have markedly altered the ecology of the Arctic Ocean.
Keywords
sea icephytoplankton bloomsmelt pondsclimate changesub ice phytoplankton bloomscryosphereAmerican Society for Engineering Education (US)ID0E4BAK15658NDSEGHorvat Christopher http://dx.doi.org/10.13039/100000001National Science FoundationID0EYHAK156591321794Horvat Christopher National Science Foundation (US)ID0EVNAK156601321794Jones David Rees National Science Foundation (US)ID0EETAK156611321794Iams Sarah CopyeditorJustin Noriel
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INTRODUCTION
Phytoplankton are a fundamental component of Earth’s oceanic ecosystem and carbon cycle. These photosynthetic organisms inhabit the upper layers of the sunlit ocean, converting carbon dioxide into the organic compounds that sustain oceanic life. Through their growth and decay, they form the foundation of the oceanic food web and constitute a major sink for atmospheric CO2 (1). Phytoplankton populations undergo periods of rapid growth, known as “blooms,” which occur annually and semiannually in many of the world’s ice-free oceans (2). In the Arctic, blooms are traditionally assumed to occur annually at the retreating sea ice edge (3). Because sea ice is optically thick, with a high albedo, regions underneath a full sea ice cover have been considered incapable of supporting photosynthetic life. This paradigm was overthrown in July 2011 by the observation of a “massive” phytoplankton bloom underneath a region of the Arctic fully covered by sea ice (4), with concentrations of particulate organic carbon among the highest ever recorded in the world’s oceans. During the period in which the bloom was observed, the sea ice was heavily covered by melt ponds, which form on the sea ice surface from melting snow and ice in the spring and summer. Because they have a lower albedo than bare ice, it has been hypothesized that melt ponds can transmit sufficient light through the thinner Arctic ice cover and sustain primary production, even when the ocean is fully ice-covered (5).
There has been recent speculation about the extent and frequency of phytoplankton blooms under Arctic sea ice (6). If sub-ice blooms are common, then the annual amount of primary production and carbon fixation occurring beneath the sea ice in the Arctic Ocean may have been underestimated by an order of magnitude (4, 7). Therefore, the focus of this study is to investigate the potential occurrence of these blooms in the modern Arctic and examine the changing potential for these blooms over the past 30 years, leveraging recent developments in the modeling of melt pond formation on sea ice (8, 9). To do so, we develop a critical-depth model for regions of the ice-covered Arctic Ocean, incorporating the light-transmitting properties of melt ponds. A recent study [(10), hereafter J16] compared three ice-ocean ecosystem models to evaluate trends in under-ice and Arctic primary production over the past 30 years and found a small overall reduction in sub-ice primary production over this period. However, none of the models contributing to the J16 intercomparison consider melt ponds, which play a role in the development of sub-ice blooms, as discussed below.
On the basis of our modeling study, we find that events like the Chukchi bloom may be routine in the modern Arctic: Over the past decade, the light conditions necessary to permit sub-ice blooms may have existed over nearly 30% of the Arctic region in July. We find these conditions only in the past two decades, driven by a thinning Arctic sea ice cover. The modern Arctic is undergoing a major ecological shift because of climate change: Projections of a thinner Arctic sea ice cover mean that the likelihood and extent of sub-ice phytoplankton blooms may further increase in the future.
MODEL
The most widely used model for describing the timing and initiation of light-limited phytoplankton blooms is the Sverdrup critical depth hypothesis (11). The critical depth hypothesis has been examined, updated, and expanded in many oceanographic settings (12, 13), although it offers a simplistic treatment of biology and ocean mixing (14, 15). It asserts that phytoplankton populations are continuously mixed vertically within the ocean mixed layer, growing in proportion to the availability of light and dying at a uniform rate. We consider a region of bare sea ice of thickness h, of which a fraction φ is covered by melt ponds, and model the mean specific growth and death rates of a population of phytoplankton in a mixed layer of depth D. We also assume that ocean velocities are comparable to ice drift velocities, appropriate in the high ice concentration regions considered here, and therefore, as phytoplankton populations grow, they do not advect into regions of different ice cover. Further discussion of this model, which outlines the model equations in more detail, is provided in Materials and Methods. The mean specific loss rate (per plankter) over the mixed layer is constant L(D)=Γ(1)
The mean specific growth rate, G(D), is proportional to the availability of photosynthetically available radiation (PAR; solar radiation ranging from 400 to 700 nm) G(D)=μI0κwD(1−e−κwD)[(1−ap)φ+(1−ai)(1−φ)]e−κih(2)
Equation 2 is the product of three terms: the first describes the mean growth rate of the phytoplankton population in a region with a mixed layer of depth D that is ice-free, where κw = 0.12 m−1 (16) is a bulk irradiance extinction coefficient of PAR in clear water, following Beer’s law. The coefficient μ, which relates the growth rate of phytoplankton to the availability of PAR, is derived from the factor Γ/μ, termed the “compensation irradiance,” which is estimated as 4.5 W m−2, based on observations in the North Water Polynya and North Atlantic (see Materials and Methods) (13, 17). I0 is the PAR incident on the ice or pond surface (in unit W m−2). The second term in Eq. 2 describes the reflection and backscatter of PAR at the ice or pond surface. The disposition of incoming PAR in the ice and to the ocean below is determined by assuming that a shallow scattering layer exists at the ice surface that is included in the parameterization of albedo, where αp
= 0.2 and αi = 0.76 are the spectral albedoes of PAR for melt ponds and bare sea ice, respectively (18–23). The focus of this study is on months in which melt ponds have formed, and therefore, the presence of snow on ice is not a focus here. To avoid unrealistic amounts of solar radiation beneath sea ice in the months before the snow cover melts, we set the ice albedo to that of snow-covered ice, αi = 0.98 (18, 22, 24), until melt ponds begin to form each year. The third term in Eq. 2 describes how PAR is extinguished within the ice layer. Radiation penetrating the ice is attenuated following Beer’s law, with κi = 1.6 m−1, a bulk irradiance extinction coefficient of PAR in sea ice (19–21). We tested the sensitivity of our results to κi (see the Supplementary Materials, text S1, and fig. S1). Although the magnitude of the extent and frequency of sub-ice blooms depends on the choice of κi, there are large increasing trends in the extent and frequency of sub-ice blooms across the range of κi.
We now seek criteria that determine when a light-limited bloom is permitted. One such criterion occurs when the mixed layer depth shoals above the point where cumulative population growth and decay rates are balanced, at which point the mean specific growth rate exceeds the mean specific death rate and the population grows exponentially. This is a variant of the critical depth hypothesis (11) discussed above, including the effects of a ponded sea ice cover. Nondimensionalizing Eqs. 1 and 2 with x ≡ κwD, β≡Γ−1μI0(1−αp)e−κih , and α*≡1−αi1−αp, this condition occurs when xc=β(1−e−xc)[φ+(1−φ)α*](3) which defines a nondimensional critical depth, xc. The original Sverdrup model may be obtained from Eq. 3 by setting h = 0 (when computing β) and φ = 1 and replacing the melt pond albedo αp with the open-ocean albedo αw = 0.06. We can also give a different interpretation of the critical condition: A bloom occurs when the melt pond fraction increases to permit more light to the ocean below. The critical melt pond fraction φc is found by rearranging Eq. 3 φc=11−a*(xβ(1−e−x)−a*)(4)
When the melt pond fraction exceeds this critical value, a light-limited bloom is permitted. Therefore, the critical pond hypothesis states that light-limited phytoplankton blooms are triggered annually by a sustained increase in melt pond fraction above φc.
RESULTS
The Chukchi bloom in climatological context
We first examine the likelihood for blooms during a single summer season, using values representative of those observed during the 2011 cruise. Figure 1 (A to D) shows seasonal cycles of the parameters used in the study. Mixed layer depth data are from a combination of observational sources from the Chukchi Sea (Fig. 1A) (25). The ice thickness data used are a representative Arctic Basin seasonal cycle over the period 2000–2012 (Fig. 1B) (26). Solar irradiance data are from the National Centers for Environmental Prediction (NCEP-2) reanalysis climatology at 72.5°N 170°W (Fig. 1C) (27). An example seasonal cycle of melt pond fraction is taken as the 2012 Arctic-wide mean seasonal cycle from a stand-alone simulation of CICE (Los Alamos sea ice model) (22) that includes a model for the evolution of melt ponds (Fig. 1D) (9, 28). For these values, a light-limited bloom is possible during the period of June to August (green line segments in Fig. 1, A to D), corresponding to the period of maximum solar insolation, maximum melt pond fraction, and minimum mixed layer depth. For many regions of the Arctic with a seasonal ice cover, this may be before the sea ice has melted away. Parameter values observed during the Chukchi bloom are displayed as green circles in Fig. 1 (A to D), with hashed boxes indicating ranges of mixed layer depth (20 to 30 m), ice thickness (0.8 to 1.2 m), and melt pond fraction (30 to 40%) observed during the cruise (7). Crucially, this parameter range permits the formation of a light-limited bloom during the observed period in 2011, beginning as early as mid-June. Therefore, it is possible that the Chukchi bloom may have been diagnosed using the critical depth model outlined here.
Fig. 1 Example seasonal cycles of climate variables, timing of sub-ice blooms, and model sensitivity.
(A to D) Example time series of ocean mixed layer depth (A), sea ice thickness (B), surface downwelling solar irradiance (C), and melt pond fraction (D). Blue and red curves in (A) are deviations of ±8 m from the reference mixed layer depth curve. Blue and red curves in (B) are deviations in ice thickness of ±40 cm from the reference ice thickness curve. Green shaded line segments of the black curves in (A) to (D) indicate a sub-ice bloom is permitted. Green dots and gray boxes correspond to the average observed values and reported ranges observed during the 2011 bloom (4). (E and F) Sensitivity of bloom timing to perturbations in the reference seasonal cycle shown in (A) to (D). (E) The critical melt pond fraction φc calculated using the seasonal cycles of ocean mixed layer depth displayed in (A) (black solid, red dash-dot, and dashed blue curves). Gray curve is the seasonal cycle of melt pond fraction shown in (D). When curves of φc are lower than the dashed curves, a light-limited bloom would be permitted in that region. (F) Same as (E) but for the ice thickness seasonal cycles shown in (B).
We examine the model sensitivity to mixed layer depth by offsetting the reference seasonal cycle of mixed layer depth (Fig. 1A, black line) by ±8 m (Fig. 1A, blue dashed and red dash-dot lines). These perturbations are significant relative to the baseline seasonal cycle, which shoals to below 13 m in July, and significantly larger than uncertainty estimates for mixed layer depth in the Chukchi Sea of ±3.3 m from a recent mixed layer depth climatology (25). Therefore, this perturbation bounds the sensitivity of this model to uncertainty in mixed layer depth data retrieval and climatology. For each perturbed seasonal cycle, we compute the critical melt pond fraction φc using Eq. 4 and plot it in Fig. 1E. Each critical melt pond fraction curve corresponds to one of the mixed layer depth curves plotted in Fig. 1A, which is either the reference seasonal cycle (solid black line), a shallower mixed layer (dash-dot red line), or a deeper mixed layer (dashed blue line). The gray line in Fig. 1E is the seasonal cycle of melt pond fraction φ, shown in Fig. 1D. When the seasonal melt pond fraction intersects with a critical melt pond fraction curve, the criterion expressed in Eq. 4 is satisfied, and a light-limited bloom is permitted. Phytoplankton populations in shallow mixed layers spend a relatively larger proportion of time in well-illuminated regions, and hence, a reduction in the mixed layer depth leads to an earlier bloom onset, with differences in the timing of a bloom of several weeks. Despite the large offset in the seasonal cycle, blooms are permitted even in the case of the deepest mixed layer.
The timing of sub-ice blooms is strongly sensitive to variations in sea ice thickness. Figure 1F again plots curves of φc, now corresponding to offsetting the ice thickness seasonal cycle (Fig. 1B, black line) by ± 40 cm (Fig. 1B, dashed blue and dash-dot red lines). This perturbation is roughly 25% of the reference sea ice thickness in June and is a variation in ice thickness smaller than the observed changes in Arctic sea ice thickness over the past 50 years (29). Therefore, the offset in ice thickness considered in Fig. 1 (B and F) may be considered small relative to the offset examined previously in mixed layer depth (Fig. 1, A and E). Thinner ice attenuates less light and permits blooms as early as mid-May, just as melt ponds begin to form. By contrast, thicker ice attenuates more light and permits no blooms, even when the melt pond fraction is at its maximum. Note that no bloom was observed until 2011 and that the ice in the Chukchi Sea used to be much thicker, a pair of observations that are consistent with our model. This contrasts with the models considered within the J16 intercomparison, which all predict a summer bloom in the Chukchi Sea in every year since 1978. We next consider the issue of Arctic change in more detail.
Sub-ice blooms in a changing Arctic
Arctic sea ice has changed markedly over the past three decades. The large-scale thinning of sea ice observed in the submarine and satellite record (29) as well as the increase in melt pond fraction seen in satellite observations and model simulations (28, 30) suggest that the potential for sub-ice blooms has also evolved. We examine a combination of model and reanalysis data over the period 1986–2015 to investigate the potential for a trend of sub-ice phytoplankton blooms in the Arctic.
Daily sea ice thickness, ice concentration, and melt pond fraction are from a stand-alone simulation of the sea ice model CICE (22), including a prognostic model for the evolution of melt ponds (see the Supplementary Materials, text S2, and fig. S2 for maps and time series of these data) (9, 28). The melt pond distributions of the CICE simulation are consistent with in situ observations and pond statistics for the period 2002–2011 based on MODIS satellite data (30–32). Although these existing data are too limited to fully validate the simulated melt pond distribution, the general pattern and evolution of time are within the range of field observations and detailed process studies, which were verified with observations (33, 34).
In recent years, the advent of ice-capable Argo floats (35) that can sample ocean properties in seasonal ice zones, ice-tethered profilers anchored to perennial sea ice (36), and historical hydrographic data bring the possibility of an Arctic mixed layer depth climatology within reach (25). However, data coverage is still neither spatially uniform nor seasonally consistent, and observational gaps exist, particularly in the shallow continental shelves. Therefore, our data on ocean mixed layer depths are taken from the Monthly Isopycnal and Mixed-layer Ocean Climatology (MIMOC), which combines Argo float, ship-board, and ice-tethered profiler data (37). Because of the sparsity of data, we use the same annual cycle of mixed layer depth for each year. As previously discussed, the model is insensitive to perturbations in mixed layer depth. Surface shortwave irradiance data are from the NCEP-2 reanalysis (27). All data are interpolated to a 0.5° by 0.5° grid for latitudes greater than 60°N and a temporal resolution of 1 per day.
At each ocean grid point, we calculate whether conditions can lead to phytoplankton population growth using the critical pond criterion, Eq. 4. To restrict our interest to only Arctic sub-ice blooms, we excluded grid cells with less than 80% ice concentration, typically defined as the “marginal ice zone,” from the calculation (in contrast to J16, which included these regions when computing under ice primary production). As mentioned above, the marginal ice zone was previously considered the only site where sub-ice phytoplankton blooms were possible (38, 39), but the focus of this study is on blooms underneath sea ice, where open-ocean or marginal ice zone processes, like wind-driven vertical mixing, are less important. We additionally exclude Baffin Bay from the study region to focus on the Arctic Basin alone. The binary data on whether conditions support a bloom are then binned into the calendar months May, June, and July and averaged over each of the time periods 1986–1995, 1996–2005, and 2006–2015. Figure 2 shows the average number of days in each month and each decade that sufficient solar radiation reaches the ocean to satisfy the critical pond hypothesis (because any area with greater than 80% ice concentration at least once during each period is included in the analysis, some regions with an average ice concentration of less than 80% during a given decade are shown as ice-covered in Fig. 2). Estimated sensitivity ranges are provided in the Supplementary Materials and tables S1 and S2.
Fig. 2 Spatial map of the average number of days of sufficient light for sub-ice phytoplankton blooms over time.
(A to C) Shading indicates the number of days in May, from 1986 to 1995 (A), 1996 to 2005 (B), and 2006 to 2015 (C), where a sub-ice bloom is permitted. (D to F) Same as (A) to (C) but for June. (G to I) Same as (A) to (C) but for July. Red boxes in (D) to (F) indicate the region of the 2011 cruise. Baffin Bay and regions with an ice concentration less than 80% at every point during each time period are colored blue. Continents are colored gray.
May sea ice conditions generally do not support sub-ice blooms in all three decades (Fig. 2, A to C), apart from the lower latitudes of the European Arctic and Kara Sea near the marginal ice zone, where the sea ice is thin. In these locations, sufficient PAR for a phytoplankton bloom penetrates through the ice once per month at most, on average. Conditions leading to a sub-ice bloom are generally not found in the Chukchi Sea at any point in May over any of the analyzed time periods.
The calculated prevalence of sub-ice bloom-permitting conditions during June has increased markedly (Fig. 2, D to F). Over the period 1986–1995, small regions of the European and Russian Arctic near the ice edge and off the coast of Greenland have sufficient light penetration to permit a bloom, up to twice a month on average. From 1996 to 2005, these regions expand, with regions of the European Arctic and Kara Sea having bloom-permitting conditions up to eight times per month (Fig. 2E). In the decade 2006–2015, in the month of June (Fig. 2F), a wide swath of the Russian Arctic has sufficient light conditions to permit a sub-ice bloom at least 5 days per month, with frequencies reaching over 10 days per month in the East Siberian Sea and Kara Sea. Conditions supportive of the massive sub-ice bloom observed in the Chukchi Sea in 2011 (4) are found over the most recent two decades and are much more prevalent from 2006 to 2015. The region in which it was observed (Fig. 2, D to F, red box) experiences a large increase in bloom likelihood over the study period. From 1986 to 1995 (Fig. 2D), the light conditions necessary to support sub-ice blooms occurred with a frequency of less than 1 day per month. Over the period 1996–2005 (Fig. 2E), there was sufficient under-ice light for a bloom to occur roughly 1 day per month in June. From 2006 to 2015 (Fig. 2F), these conditions arose on average 5 days per month. Light conditions that may lead to the initiation of a sub-ice bloom also occur increasingly throughout the Arctic in July (Fig. 2, G to I), reaching to the interior of the Arctic. From 2006 to 2015, the bloom-permitting conditions arose more than 7 days per month across the Russian and European Arctic and up to 5 days per month in the Chukchi Sea.
To quantify whether a region in the Arctic Ocean (which we again define as all ocean points north of 70°N, excluding Baffin Bay) may have had a sub-ice bloom, a region is defined to be bloom-permitting in each month that it absorbs sufficient light for growth for three consecutive days. Phytoplankton growth rates observed in the 2011 Chukchi bloom exceeded 1 per day; therefore, these bloom-permitting areas permit sufficient light for at least three doublings of the phytoplankton population. Figure 3 (A to C) shows a time series of the fraction of the Arctic Ocean meeting this criterion in each calendar month. The results support the hypothesis that large-scale changes to the sea ice cover have triggered a new ecological paradigm: In June, the fraction of the Arctic supporting sub-ice blooms in each year increases by 5% per decade, from less than 3.0% in 1986 to an average of 13.1% over the period of 2006–2015, with a maximum yearly percentage of 23% in 2007. In July, the effect is similarly significant, increasing by 7% per decade from less than 5% in 1986 to an average of 21.3% over the period 2006–2015, with a maximum of 28% in 2013. Each time series has a significant amount of year-to-year variability in bloom-permitting fraction due to the changing regional ice, ocean, and atmospheric conditions. This level of year-to-year variability in blooming is not demonstrated in the J16 intercomparison.
Fig. 3 Evolution and variability of the pan-Arctic likelihood of sub-ice blooms over time.
(A to C) Percentage by area of the Arctic Ocean that has greater than 80% ice concentration and permits growth for at least three consecutive days in May (A), June (B), and July (C). Red dashed lines are linear fits to the data.
To attribute these changes to trends in sea ice thickness and melt pond fraction, we perform a set of attribution studies, with results shown in Table 1. In each case, we fix one or more fields (ice concentration c, melt pond fraction φ, or ice thickness h) at average values from 1986 to 1995 in each month (May, June, and July). We then compute the percentage of the Arctic that is bloom-permitting from 2006 to 2015, allowing the other variables to vary in time. By comparing the model output when all fields vary together to the output when each trend is suppressed in turn, we can infer which fields have had the most significant limiting effect on the increasing trend demonstrated in Fig. 3. In interpreting the results of Table 1, note that when a field is “fixed,” this removes the effects of the trend in this field (increasing melt pond fraction, decreasing ice thickness, and decreasing total ice concentration).
Table 1 Analysis of the causes of changes in sub-ice blooms in the Arctic Ocean.
The average fraction of the Arctic Ocean that permits a light-limited sub-ice bloom from 2006 to 2015 when labeled external fields are held constant at their mean 1986–1995 values. The Arctic is defined as the region with latitudes greater than 70°N, excluding Baffin Bay. Percentage by area refers to the average area of the Arctic with an ice concentration greater than 80%, in which at least three consecutive days permit enough light for a light-limited bloom to occur, averaged over the time period 2006–2015. The notation “x fixed” refers to output when the variable x is fixed at its mean 1986–1996 values. Variables that may be fixed are the ice thickness h, melt pond fraction φ, and ice concentration c. The final row is the average fraction of the Arctic Ocean that permits a light-limited sub-ice bloom from 2006 to 2015 when the melt pond fraction φ is is always equal to zero.
May % area June % area July % area
None fixed 1.1% 13.1% 21.4%
h fixed 0.3% 1.5% 2.2%
φ fixed 3.5% 7.9% 16.2%
c fixed 2.1% 16.0 % 31.1%
h, c fixed 0.3% 1.1% 2.0%
φ, c fixed 5.5% 11.6% 29.5%
φ, h fixed 0.9% 1.4 % 1.6%
φ = 0 0.8% 4.4% 6.1%
When the trend in melt pond fraction is suppressed, φ is fixed at its mean 1986–1995 values, and sea ice thickness and concentration vary. In this case, 7.9% of the Arctic Ocean permits blooms in June and 16.2% in July over 2006–2015. When the trend in sea ice thickness is suppressed instead and φ varies in time, the fraction of the Arctic Ocean that supports sub-ice blooms over 2006–2015 is 1.5% in June and 2.2% in July. From this, we infer that the thinning of sea ice has had a more significant direct effect on the increasing spatial coverage of bloom-permitting regions in June and July than has the increasing trend in melt pond fraction.
Over the period 1986–2015, the area covered by sea ice in the Arctic has decreased significantly (see the Supplementary Materials and fig S2). The percentages reported above are computed as fractions of the Arctic Ocean, not of the ice-covered regions. Any increase in bloom-permitting fraction occurs despite the declining ice-covered area, which has reduced the available percentage of the Arctic Ocean that could permit sub-ice blooms from May to July. We can evaluate the significance of the declining sea ice area coverage by fixing the sea ice concentration field at its 1986–1995 average values. In this case, the fraction of the Arctic that has sufficient light to permit sub-ice blooms is 2.1% in May, 16.0 % in June, and 31.1% in July on average over the period 2006–2015, indicating that the decrease in sea ice area coverage has decreased the extent of the Arctic that may experience sub-ice blooms. Regions that were ice-covered from 1986 to 1995, but not from 2006 to 2015, may still experience phytoplankton blooms tied to the retreating ice edge, as discussed in the study of Perrette et al. (3).
To consider whether trends in bloom-permitting fraction may be suppressed by the declining sea ice area over the period 1986–2015, we consider the bloom-permitting fraction over 2006–2015 when the ice concentration field is fixed at its 1986–1995 average. When the ice thickness trend is also held at its 1986–1995 average, a smaller proportion of the Arctic is found to be bloom-permitting than when the melt pond fraction is also held at its 1986–1995 average (1.1% versus 11.6% in June and 2.0% versus 29.5% in July).
Both Pan-Arctic average sea ice thickness and melt pond fraction have significant trends over the study period (see the Supplementary Materials and fig S2). From these attribution studies, we conclude that the direct cause of the increase in Pan-Arctic bloom potential is a declining sea ice thickness field, with the increasing trend in melt pond fraction having a comparatively insignificant effect. This does not account for the relationship between pond fraction and sea ice thickness. Melt ponds are significant for sub-ice blooms in two ways. First, sea ice thinning is enhanced by increasing melt pond fraction. Because of the reduced surface albedo of ponded ice, melt ponds increase the absorption of solar radiation within the sea ice itself, thereby boosting its melting and thinning it (20, 21). CICE simulations that include the prognostic evolution of melt ponds have thinner ice than those that do not (9). Over the period 2006–2015, ice thickness is reduced in simulations with melt pond evolution by 3.8 cm in May, 4.5 cm in June, and 25.2 cm in July in the ice-covered regions considered by our analysis. Second, melt ponds are needed for there to be a significant overall potential for sub-ice blooming. When the melt pond fraction is set to be zero in all ice-covered regions, the percentage of the Arctic that is bloom-permitting from 2006 to 2015 is less than 1% in May, 4.4% in June, and 6.1% in July (Table 1, final row).
DISCUSSION
The observation of a phytoplankton bloom underneath sea ice in July 2011 represented a major change in the scientific understanding of the Arctic Ocean and its ecology. We find that this may be a consequence of the thinning of the Arctic sea ice cover observed over the satellite era. Sea ice conditions permitting sufficient PAR for sub-ice blooms have become common in the present-day Arctic, having been rare 30 years ago. In our analysis, we find that these conditions may have existed over 30% of the Arctic in recent years, in the months of June and July, with changes driven primarily by declining sea ice thickness. This indicates that climate change has markedly altered the ecological underpinnings of the Arctic Ocean and its carbon cycle (40). The greater-than-expected net primary productivity under sea ice has been discussed in the context of the Chukchi bloom (4, 7). Therefore, those authors’ extrapolations of the impacts of these blooms on the Arctic carbon cycle based on the Chukchi bloom are supported by our modeling study.
The model described above is based on the long-standing paradigm that blooms in the Arctic Ocean are light-limited, as evidenced by the fact that they are tied to the seasonal retreat of the ice edge (3). This is only a necessary condition for sub-ice blooms. The presence or lack of nutrients may also limit the genesis of blooms. Therefore, predictions of sub-ice blooms in the modern Arctic will require modeling of the under-ice nutrient distribution alongside the light distribution to support and confirm contemporaneous observations. Observing these blooms remains a challenge because satellites do not observe chlorophyll through sea ice and ship-based measurements are expensive and localized. Therefore, the results of this study should prove useful for planning future expeditions aimed at observing these blooms. We would suggest the use of moorings in the high–bloom likelihood regions seen in Fig. 2, in the Chukchi Sea or Russian Arctic, to validate the results presented above and observe the Pan-Arctic frequency of sub-ice blooms. In the future, because the Arctic sea ice continues to thin, the frequency and extent of June and July blooms may increase even further. The specific consequences of this marked shift in the Arctic marine ecosystem and carbon budget are an important area for future inquiry.
MATERIALS AND METHODS
Sub-ice critical depth model
The time evolution of the cumulative population of phytoplankton 𝒫(D), over a mixed layer of depth D, is described by the equation ∂𝒫(D)∂t=(G(D)−L(D))𝒫(D)(5) where G(D) (in unit s−1) is the mean specific (per plankter) growth rate up to a depth D and L(D) (in unit s−1) is similarly the mean specific population loss rate up to a depth D. Equation 5 implies that the phytoplankton population grows exponentially when growth exceeds loss [G(D) − L(D) > 0).].
The mean growth rate G(D) of phytoplankton populations depends on converting solar radiation ranging from 400 to 700 nm, known as PAR, into energy. In a region covered by sea ice of thickness h, we modeled the PAR at a depth z below the ice according to previous studies (18, 19) Ii(z)=I0(1−ai)e−κiheκwz where I0 is the PAR incident on the ice surface (in unit W m−2), αi = 0.76 is the albedo of bare ice assuming a shallow scattering layer at the ice surface, κw = 0.12 m−1 is the coefficient of extinction of PAR in clear water, κi ≈ 1.6 (in unit m−1) is the extinction coefficient of PAR in sea ice, both following Beer’s law, and z is negative downward. Ponded ice has a surface albedo αp = 0.2 that accounts for scattering within the pond layer; therefore, the radiation penetrating the pond to the ice below is (1 − αp)I0. The PAR, Im(z), under a melt pond at a depth z for ice of thickness h is Im(z)=I0e(−κih)(1−ap)eκwz
We assumed that phytoplankton populations are well mixed laterally on scales larger than the typical spacing of melt ponds and respond to a weighted average of the PAR by melt pond area fraction. The total PAR, I(z), underneath a region of ponded ice of thickness h and melt pond area fraction φ is I(z)=φIm(z)+(1−φ)Ii(z),=I0e−κih[(1−ap)φ+(1−φ)(1−ai)]eκwz(6)
Phytoplankton growth at depth z was assumed to be linearly related to the light intensity I(z) with a proportionality coefficient μ (in unit m J−1) (11). Phytoplankton decay was assumed uniform, independent of z, at a rate Γ (in unit m−1 s−1). The mean growth rate was then determined by integrating Eq. 6 G(D)=μD∫−D0I(z)dz=μI0κwD(1−e−κwD)×[(1−ap)φ+(1−φ)(1−ai)]×e−κih
The mean death rate L(D) is simply L(D)=1D∫−D0Γdz=Γ
Parameters used to evaluate sub-ice blooms
The compensation irradiance, Γ/μ was estimated using data from the North Water Polynya (17), with units of mol quanta m−2 d−1 (where d = day) and a range of 1.9 ± 0.3 mol quanta m−2 d−1. Γ/μ was measured in the North Atlantic via satellite (13), with values in a similar range (1.3 ± 0.3), although to the authors’ knowledge, no similar measurements exist in the high Arctic. On the basis of this similarity, we assumed that the magnitude of this factor is relatively spatially uniform and in this range in the Arctic. The conversion factor from these units to W m−2 was approximately 2.5 W mol−1 quanta d−1 for PAR from sunlight; thus, we approximated Γ/μ = 4.5 W m−2 as a representative value. The clear-water attenuation coefficient ranged from 0.09 to 0.16 m−1 for wavelengths in the range (412,555) (16). We chose 0.12 m−1 as a representative value.
Supplementary Material
http://advances.sciencemag.org/cgi/content/full/3/3/e1601191/DC1
Acknowledgments
We thank A. Wells and M. Miller for their most helpful comments on an earlier version of this manuscript. C.H., S.I., D.R.J., and D. Flocco attended a Mathematical Research Community supported by this grant on “Differential Equations, Probability, and Sea Ice,” and acknowledge helpful and illuminating discussions with many of the participants, particularly K. Golden and C. Barry. Funding: This work was supported by the NSF under grant no. 1321794. D.R.J. acknowledges support from the John Fell Oxford University Press Research Fund. C.H. was supported by the Department of Defense through the National Defense Science and Engineering Graduate Fellowship Program. Author contributions: C.H. conceived the model. C.H., S.I., and D.R.J. developed the model equations, performed the analysis of the model equations, and jointly wrote and edited the manuscript. D. Flocco also discussed the model development at the outset of the project. C.H., S.I., D.R.J., and D.S. subsequently designed the Arctic change and sensitivity analyses, which C.H. performed. D.S., D. Flocco, and D. Feltham provided model data and analysis for the Arctic change section. All authors jointly discussed and analyzed the data, results, conclusions, and implications. Competing interests: The authors declare that they have no competing interests. Data and materials availability: All data needed to evaluate the conclusions in the paper are present in the paper and/or the Supplementary Materials. Additional data related to this paper may be requested from the authors.
SUPPLEMENTARY MATERIALS
Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/3/3/e1601191/DC1
text S1. Sensitivity to extinction coefficient in ice.
text S2. Evolution of fields over time.
text S3. Sensitivity analysis: Bounds on the area that permits sub-ice blooms.
fig. S1. Sensitivity of bloom-permitting area to ice extinction coefficient.
fig. S2. Evolution of ice concentration, melt pond fraction, and ice thickness over time.
table S1. Ranges of the percentage of the Arctic Ocean (>70°N, excluding Baffin Bay) in which sub-ice blooms can occur, when sea ice thickness data are increased or decreased by 1 SD (for details on how this is computed, see text S2).
table S2. Ranges of the percentage of the Arctic Ocean (>70°N, excluding Baffin Bay) in which sub-ice blooms can occur, when the melt pond coverage data are increased or decreased by 1 SD (for details on how this is computed, see text S2).
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Sci AdvSci AdvSciAdvadvancesScience Advances2375-2548American Association for the Advancement of Science 28435856160051310.1126/sciadv.1600513Research ArticleResearch ArticlesSciAdv r-articlesEvolutionary BiologyDynamic microbiome evolution in social bees Kwong Waldan K. http://orcid.org/0000-0001-7999-321712*Medina Luis A. http://orcid.org/0000-0001-8660-20422Koch Hauke 2†Sing Kong-Wah 3‡Soh Eunice Jia Yu 4Ascher John S. 4Jaffé Rodolfo http://orcid.org/0000-0002-2101-528256Moran Nancy A. http://orcid.org/0000-0003-2983-97692*1 Department of Ecology and Evolutionary Biology, Yale University, New Haven, CT 06511, USA.2 Department of Integrative Biology, University of Texas, Austin, Austin, TX 78712, USA.3 Institute of Biological Sciences, Faculty of Science, University of Malaya, 50603 Kuala Lumpur, Malaysia.4 Department of Biological Sciences, National University of Singapore, Singapore 117543, Singapore.5 Vale Institute of Technology, Sustainable Development, 66055-090 Belém PA, Brazil.6 Department of Ecology, Universidade de São Paulo, Rua do Matão 321, 05508-090 São Paulo SP, Brazil.* Corresponding author. Email: waldan.kwong@yale.edu (W.K.K.); nancy.moran@austin.utexas.edu (N.A.M.)† Present address: Royal Botanic Gardens, Kew, Richmond, Surrey TW9 3AB, U.K.
‡ Present address: State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, People’s Republic of China.
3 2017 29 3 2017 3 3 e160051310 3 2016 10 2 2017 Copyright © 2017, The Authors2017The AuthorsThis is an open-access article distributed under the terms of the Creative Commons Attribution-NonCommercial license, which permits use, distribution, and reproduction in any medium, so long as the resultant use is not for commercial advantage and provided the original work is properly cited.Honey bees, bumble bees, and stingless bees have related gut microbial communities that are shaped by host evolutionary history.
The highly social (eusocial) corbiculate bees, comprising the honey bees, bumble bees, and stingless bees, are ubiquitous insect pollinators that fulfill critical roles in ecosystem services and human agriculture. Here, we conduct wide sampling across the phylogeny of these corbiculate bees and reveal a dynamic evolutionary history behind their microbiota, marked by multiple gains and losses of gut associates, the presence of generalist as well as host-specific strains, and patterns of diversification driven, in part, by host ecology (for example, colony size). Across four continents, we found that different host species have distinct gut communities, largely independent of geography or sympatry. Nonetheless, their microbiota has a shared heritage: The emergence of the eusocial corbiculate bees from solitary ancestors appears to coincide with the acquisition of five core gut bacterial lineages, supporting the hypothesis that host sociality facilitates the development and maintenance of specialized microbiomes.
Keywords
gut microbiotahoney beesbumble beesstingless beesMicrobial ecologyspecies-area relationshiphttp://dx.doi.org/10.13039/501100002790Canadian Network for Research and Innovation in Machining Technology, Natural Sciences and Engineering Research Council of CanadaID0EEQDI15286Kwong Waldan K. http://dx.doi.org/10.13039/501100001711Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen ForschungID0EUVDI15287147881Koch Hauke http://dx.doi.org/10.13039/501100001807Fundação de Amparo à Pesquisa do Estado de São PauloID0EG2DI152882012/13200-5Jaffé Rodolfo http://dx.doi.org/10.13039/501100001807Fundação de Amparo à Pesquisa do Estado de São PauloID0ETBAK152892013/23661-2Jaffé Rodolfo http://dx.doi.org/10.13039/501100001711Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen ForschungID0E6HAK15290140157Koch Hauke http://dx.doi.org/10.13039/100000001National Science FoundationID0ERNAK152911046153Moran Nancy A. http://dx.doi.org/10.13039/100000001National Science FoundationID0ESSAK152921415604Moran Nancy A. CopyeditorMikee Bernabe
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INTRODUCTION
Social behavior is one of the great evolutionary innovations of life, permitting its adopters to realize novel organizational complexities and providing competitive advantages and fitness benefits to groups working together; these interactions have been fundamental to the origins of multicellularity (1), developmental specialization (2), and culture and technology (3). Sociality affects all aspects of an organism’s biology, and there is accumulating evidence that this includes host-associated gut microbial communities as well. The reliability of transmission brought about by social contact potentially allows for stable, long-term microbial assemblages to establish and for host-adapted symbiont lineages to arise (4–10). Nonetheless, how gut microbiomes evolve—through changes in community composition, diversity, and functional capabilities—is not well understood, and the forces guiding these evolutionary trajectories remain unclear.
The eusocial Western honey bee (Apis mellifera) harbors a distinctive gut microbiota, composed of <10 bacterial phylotypes that are transmitted through contact between nestmates (11–13). These bacteria are extremely specialized, usually found in bee guts or the hive environment but not elsewhere (14, 15). However, A. mellifera is but one of more than 775 species of social corbiculate bees—a clade dating to about 80 million years and containing other ecologically important pollinators such as the Eastern honey bee (Apis cerana), bumble bees (tribe Bombini, all in genus Bombus), and stingless bees (tribe Meliponini) (16). Previous studies found that diverse bumble bee species harbor gut associates related to those of A. mellifera (14, 17–21), suggesting that an evolutionarily ancient microbiota is conserved among the eusocial corbiculates.
Here, we compare the gut microbiomes of honey bees (tribe Apini, all in genus Apis), bumble bees, and stingless bees—the three major groups of eusocial corbiculates—using samples collected from multiple locations on four continents (Fig. 1). This approach enables us to (i) define the normal gut microbiota of corbiculate bees, (ii) determine whether gut community structure is influenced by phylogenetic relatedness and geographic co-occurrence, (iii) infer shifts in the microbiota over host evolutionary history, and (iv) evaluate how host ecology shapes microbiome composition and diversity. We also use in vivo experiments with cultured bacterial strains to evaluate potential barriers to cross-host gut symbiont exchange. Our results show that, as with humans and several other social animals, the eusocial corbiculate bees have highly characteristic gut communities whose origins and maintenance may be facilitated by their social nature.
Fig. 1 Distribution of the eusocial corbiculate bees and sample collection sites.
The honey bees (Apis spp.) are largely restricted to South and East Asia, with the exception of A. mellifera and an introduced population of A. cerana in Australia. Stingless bees (pictured; H. itama) are found in tropical and subtropical regions, including Africa. Bumble bees (pictured; B. impatiens) in this study were collected from several sites in the United States. Biogeographical data are from previous studies (34, 60, 120, 121).
Photo credits: W. K. Kwong and J. S. Ascher/www.discoverlife.orgRESULTS
We examined the gut microbiota of 472 individual adult bees representing 25 species of corbiculates and two outgroup bee species (data file S1). The V4 region of the bacterial 16S rRNA gene was amplified and sequenced on the Illumina MiSeq platform, generating, on average, 26,672 reads per sample (range, 2313 to 80,286).
Corbiculate bees harbor a small, recurring set of bacterial phylotypes
Gut communities were profiled at a depth of 1900 reads per sample. Despite the antiquity of this clade and the span of geographic regions, habitats, and nesting behaviors represented, the eusocial corbiculate bees have markedly low gut community diversity at 97% operational taxonomic unit clustering (OTU97), with only 199 OTUs in total. Individual specimens have from 1 to 22 OTUs97 [comparatively, humans have 500 to 1000 OTUs97 (22) and termites have ~102 to >103, depending on species (7)]. The same phylotypes [phylogenetically related OTUs, according to Martinson et al. (14)] are found across diverse corbiculate species: For instance, OTUs corresponding to the genus Snodgrassella were detected in all Apis and Bombus species surveyed, as well as in 9 of 13 stingless bee species. Similarly, Gilliamella, Bifidobacterium, Lactobacillus Firm-4, and Lactobacillus Firm-5 are prevalent across the three major corbiculate clades, suggesting that these taxa comprise the core of the corbiculate gut microbiome (Fig. 2 and data file S2). Some phylotypes appear lineage-specific: Bartonella apis (23) and Frischella (24) in honey bees, Bombiscardovia (25) and Schmidhempelia (26) in bumble bees, and an Acetobacter-like OTU in the stingless bees. These bacteria are largely absent in our outgroups, the solitary Centris atripes (an oil-collecting bee in a tribe that is sister to the corbiculates) and the miner bee Anthophora abrupta, and were also not found in other noncorbiculate bees and wasps (14).
Fig. 2 Gut microbial community profiles of sampled bee species.
Bacterial taxa were categorized on the basis of the OTU97 taxonomic assignments (see data file S2). Relative abundances, as averaged over all samples for each host species, are given as percentages. Prevalence heat map indicates the proportion of samples per host species carrying a bacterial taxon in >0.5% abundance. Absolute abundances of 16S rRNA gene copies represent means of quantitative polymerase chain reaction (qPCR) measures (see data file S1 and fig. S1). n = number of individuals per bee species sampled. Bombus data are from this study and the work of Powell et al. (93). *, species identified on the basis of the closest mitochondrial DNA match but unverified by morphology.
Gut communities differ among host species
Although low diversity and the presence of recurring phylotypes appear to be common characteristics uniting corbiculate gut communities, the microbiome of each host species remains distinctive when compared against that of other species. Principal coordinates analysis (PCoA) and nonmetric multidimensional scaling (NMDS) analysis of dissimilarities (Fig. 3A and figs. S2A and S3) and unweighted pair-group method with arithmetic mean clustering (UPGMA) (fig. S4) show clear separation between the three eusocial corbiculate tribes, with the greatest compositional variation within the Meliponini (PERMDISP, P < 0.001). Gut communities assorted according to host, rather than geography. For example, community makeup was not significantly different in A. cerana sampled across five countries (Fig. 3B). Sympatric bee species maintain distinct gut communities (Fig. 3C and fig. S2B), despite having ample opportunities to swap microbes at shared floral resources, during hive robbing, or in construction of interspecific colonies (27–29). Linear modeling corroborates the greater weight of host identity over sampling location in predicting gut community composition (fig. S5; likelihood ratio test, P < 1 × 10−15). These results do not rule out the existence of geographic factors but suggest that host identity is a much more important determinant of microbiome composition.
Fig. 3 Gut community similarities, compared using PCoA.
(A) All corbiculate bee samples, compared at a depth of 1900 reads per sample [see fig. S2A for plot excluding Powell et al.’s set (93)]. (B) A. cerana samples from different geographic locations, compared at a depth of 4500 reads. (C) Comparison of gut communities in sympatric bees, at a depth of 2900 (Austin, USA) or 4500 reads. See figs. S2 and S3 for additional PCoA and NMDS plots. All plots are derived from binary Sørensen-Dice dissimilarities of samples at OTU97 clustering. Analysis of similarities (ANOSIM) and permutational multivariate analysis of variance (PERMANOVA) were used for statistical testing of group similarities. The proportion of variation explained for each axis is given in parentheses. Tick marks, 0.2.
In East Asia, A. cerana has historically been the most economically important bee species, but introductions of A. mellifera, which produces greater honey yields, have recently become common (30–32). These introductions, combined with the close genetic relationship and lifestyle of the two species, have facilitated a disastrous transmission of pathogenic microbes in both directions, with various mites, viruses, and microsporidian parasites devastating naïve hosts (33). In 2007, A. cerana was inadvertently introduced to Australia at Cairns, Queensland, sparking concern for the existing apicultural industry based around A. mellifera (34). Whether the normal gut microbiotas of the two species have also become homogenized was unknown. We analyzed samples of co-occurring A. mellifera and A. cerana in four countries in 2014, as well as of historical A. cerana samples from Cairns, and found the gut communities of A. mellifera and A. cerana to be clearly distinguishable (Fig. 3C and fig. S2). This held true across different locations, implying the existence of persistent barriers to gut symbiont exchange between these closely related species.
Gut community evolution is dynamic
In terms of both phylotype prevalence and relative abundance, there is considerable variation in gut communities among bee species (Fig. 2). To understand why different bees harbor different microbiomes, we examined how gut community composition varies with degree of host relatedness. A strong correlation between pairwise community dissimilarities and host divergence was found, with closely related species having more similar microbiomes (Fig. 4A; Mantel test, r = 0.782, P < 0.0001). This correlation persisted when controlling for geography (partial Mantel test, r = 0.753, P < 0.0001), whereas the effect of geography when controlling for host relatedness was minimal (partial Mantel test, r = 0.046, P = 0.0079).
Fig. 4 Gut microbiome evolution.
(A) Microbiome dissimilarity as a function of host divergence, showing that closely related bee species have more similar gut communities. (B) Phylogenetic relationships of sampled bee species, with parsimony-inferred shifts in the microbiota over corbiculate evolution. Only gains and losses of the corbiculate core and corbiculate-specific lineages are plotted. Taxa with <1% abundance and <20% prevalence are considered losses. See Materials and Methods for details on tree inference and microbiome reconstruction.
These results suggest that host phylogeny is key to explaining gut community composition and that social corbiculate microbiomes reflect descent with modification rather than arbitrary assembly within each host. That no single bacterial phylotype is present across all bee species (Fig. 2) is indicative of bacterial lineage gain/loss being a major mechanism by which the bee microbiome evolves. Assuming that gut communities are highly heritable, shifts in the gut microbiome during the evolution of their hosts can be estimated by mapping the community compositions of extant bees onto a corbiculate phylogeny (Fig. 4B and fig. S6). This parsimony-based inference shows that the five core phylotypes were likely present at the base of the corbiculates. Every sampled corbiculate species, save Austroplebeia australis, harbors at least one of the core bacteria at >1% abundance, and each core phylotype is found within members of Apis, Bombus, and the Meliponini (Fig. 2).
In addition to the core members, other bacteria are often found in the corbiculate gut community. Some of these may be environmental in origin, acquired during foraging or from hive materials. However, others appear to be distinctively associated with particular hosts. One of the main differentiators between the A. mellifera and A. cerana microbiomes is the consistent presence of Apibacter in A. cerana (in 84.3% of individuals, compared to 4.8% in A. mellifera). Apibacter is also characteristic of the Apis dorsata microbiome (85.2% prevalence), albeit with a different strain from that found in A. cerana (data file S3) (35).
Gains of microbiota lineages are also reflected in broader host clades. For instance, we detected B. apis in all sampled Apis species, but not in Bombus or the Meliponini, suggesting that B. apis is more host-restricted than Apibacter, which is found in bees across all three clades. The gains of new microbial lineages have been tempered by apparent losses. Of the 25 sampled corbiculate species, 13 lacked detectable levels of at least one core phylotype. The extremely low abundance of Snodgrassella in A. dorsata (0.3%) may be an example of a loss in progress, whereby a previously abundant gut symbiont is gradually eliminated. It is also possible that OTU prevalence fluctuates with host age or season (36), for which further sampling is needed to ascertain.
Strain-level diversity is largely host-specific
Clustering highly conserved, slow-evolving genes such as 16S rRNA at 97% identity obscures strain-level variation. Strain-level variants can be a source of functional diversity (37, 38) and can represent specialists adapted to particular hosts or environments. For example, even though Snodgrassella strains occur in both Apis and Bombus, and are >98% similar in their 16S rRNA sequences, strains in one host are divergent from those in another and contain different genomic repertoires (39).
Clustering at 99.5% identity (OTU99.5) resolves a number of distinct strains within each phylotype, mainly assorting with host species (Fig. 5 and data file S3). The presence of host-specific strains supports the hypothesis of a coevolved, vertically transmitted gut microbiota (18) and weighs against the idea that the microbiota passes freely between bee species.
Fig. 5 Strain-level diversity in the bee gut microbiota is largely host-specific.
Relative abundances of all reads per bee species (rows) corresponding to particular OTUs99.5 (columns) are shown for selected bacterial taxa. See data file S3 for OTU99.5 diversity summaries of other taxa. For Lactobacillus Firm-5, the conserved, single-copy tuf gene was cloned and sequenced from representative samples to visualize Firm-5 diversification and relationship with host taxa. Dashed lines and coloring indicate host origins. Clades containing previously cultured members are denoted by “*” [Lactobacillus apis (40)] and “†” (41, 42). Bayesian posterior probabilities and maximum likelihood bootstrap supports, in that order, are shown at select nodes as percentage values. Displayed tree is based on Bayesian inference; bar represents nucleotide substitutions per site. See figs. S7 and S8 for uncondensed trees. Tip taxa in host phylogeny are in the same order as in Fig. 4. Cophylogenetic analysis of hosts and Firm-5 is shown in fig. S10.
The diversity of Lactobacillus Firm-5, one of the most ubiquitous and abundant members of the corbiculate microbiota, was examined at greater resolution by phylogenetic analysis of the protein-coding genes rpoA and tuf, cloned from individual bees (Fig. 5 and figs. S7 to S9). We found that the diversity represented by previously characterized Firm-5 from A. mellifera (40–43) encompasses but a small portion of this bacterial clade (Fig. 5) and that different host species tend to carry unique Firm-5 lineages. Closely related hosts generally harbor closely related strains, suggesting that some degree of host-microbe codiversification helps drive strain-level evolution (fig. S10). Firm-5 strains also resolve into clusters that reflect higher host-level taxonomies (for example, strains from bumble bees, honey bees, and the Old World and New World stingless bees group separately), albeit with lower support at deeper nodes.
In A. mellifera and A. cerana, cloned Firm-5 sequences from a single sample fall across a range of phylogenetic positions, indicating cohabitation of multiple Firm-5 strains within individual bees (fig. S9). This was true even in A. cerana from Cairns, Australia, a highly inbred population founded by a single colony (34). There was also no clustering discernible along intraspecies morphoclusters, which potentially represent different host genetic backgrounds (for example, A. cerana in Cairns versus that in Seoul) (44). Hence, the entire diversity of a host-specific phylotype might be largely represented within a single bee colony regardless of geography, at least for A. mellifera and A. cerana.
Despite the high degree of observed host specificity, the phylogenetic association between Firm-5 and host bees is not perfectly congruent (Fig. 5 and fig. S10), ruling out strict host-microbe codivergence. Gut microbiome evolution is complex and dynamic: Entire phylotypes can be gained and lost from host lineages, and it is likely that host switching of strains occurs at an appreciable frequency.
Generalist strains can colonize multiple hosts
Although host specificity appears to be prevalent, generalist strains can also be found in the corbiculate microbiota. A tuf gene phylogeny of Snodgrassella reveals clades in which closely related strains associate with multiple host species (Fig. 6A). For example, similar strains are shared between the Asian honey bees A. cerana, Apis andreniformis, and Apis florea. Other recurring, related strains are found across some bumble bee clades (18). These apparent generalists are useful for probing the barriers to gut microbe exchange and the phenomenon of host specialization.
Fig. 6 Diversity of Snodgrassella alvi and its impact on host switching.
(A) Bayesian phylogeny of S. alvi clones and cultured isolates is shown, with the strains used for colonization assays indicated by colored symbols. Bayesian posterior probabilities and maximum likelihood bootstrap supports, in that order, are shown at select nodes as percentages. Bar represents nucleotide substitutions per site. (B) Monoinoculations demonstrate that S. alvi strains from other Apis spp. are able to colonize A. mellifera [bars, mean; detection limit, 5 × 105 colony-forming units (CFUs)]. (C) Co-inoculations suggest variability in competitiveness and that A. mellifera-derived strains are not always dominant (error bars, SEM).
A. mellifera does not naturally harbor Snodgrassella strains from A. cerana, A. andreniformis, or A. florea (Fig. 5). To determine whether this segregation among hosts reflects the inability of strains to colonize other host species, we performed experiments using monoinoculations with cultured strains in germ-free workers of A. mellifera. The results show that cross-host microbe transfer is possible between Apis spp. (Fig. 6B). In contrast, there was strict host fidelity in transfers between Apis and Bombus (Fig. 6B), as previously observed (39). Hence, the barrier to host switching is not due to direct physiological incompatibility, at least between closely related hosts.
Despite the innate colonization potential of “foreign” strains, their absence in field-collected A. mellifera could also be explained if “native” strains are consistently superior competitors. We examined this hypothesis with co-inoculation trials (Fig. 6C). Surprisingly, all three foreign strains we tested were able to simultaneously colonize A. mellifera together with a native strain, albeit with different efficacies. Typically, only one strain became dominant in any single gut, but the native A. mellifera–derived strain was not always the most competitive. Varying the inoculation ratios by 10-fold produced shifts in final ratios of only ~20% (Fig. 6C), suggesting that competitiveness is a robust trait not easily perturbed.
The apparent credibility of generalist lifestyles complicates our understanding of how bee species maintain distinctive gut communities. Other barriers may be important in enforcing host fidelity. Possibly, for instance, foreign strains may have greater difficulty invading the more complex, heterogeneous gut communities found under natural conditions. The absence of generalist strains colonizing distantly related hosts could also be due to differences in host physiologies that are too great to be bridged. Additionally, host behaviors or biogeographic distribution likely helps circumscribe the microbiota exchange opportunities between bee species.
Host ecology drives microbiota diversity
Causal factors behind large-scale trends in community diversity are often difficult to pinpoint. Our results suggest that the corbiculate gut provides a superb habitat for a distinctive set of bacterial colonists, yet there is substantial variation in gut community composition between bee species and between individuals within species. For instance, we find that gut communities in bumble bees are, on average, less diverse than those in honey bees (Fig. 7A, nested ANOVA OTUs97, P = 0.0420; fig. S11, Shannon’s H OTU99.5, P = 0.0045). Bumble bee gut communities are also more erratic than those of honey bees (Fig. 7B), with individuals harboring communities ranging from having relatively even abundances to being dominated by a few phylotypes. For the stingless bees, there was significant variation between species in both diversity and evenness.
Fig. 7 Relationship between host identity, bacterial load, and microbiota diversity.
(A) Number of OTUs at 97% clustering for each bee species. The Bombus microbiota is, on average, less diverse than that of Apis, whereas there is substantial variation in the Meliponini (nested ANOVA). (B) Gut community evenness as measured by Shannon’s E on OTUs97 for each bee species. The Bombus microbiota is more erratic than that of Apis, with more variation in evenness (Levene’s test). n.s., not significant. (C) Mean bacterial abundance versus average worker size for each bee species. Larger bees harbor more bacteria (F test, excluding noncorbiculates). Dashed lines, 95% confidence interval. (D) Gut microbial diversity, as measured by Shannon’s H on OTUs99.5, versus mean bacterial abundance for each bee species. There is a weak positive correlation between diversity and community size when each corbiculate tribe is considered separately [ordinary least squares (OLS) F test, colored lines] but not together (OLS F test, black line). Correcting for phylogeny improves fit [phylogenetic generalized least squares (PGLS)]. Host taxa in (A) and (B) are in the same order as Fig. 2 and fig. S1; boxes and whiskers represent 25th to 75th and 5th to 95th percentiles, respectively, of individual samples within each bee species; bar indicates median. See fig. S11 and S12 for additional plots.
The species-area relationship (45) postulates that larger habitats harbor greater diversity. We examined total community size (absolute bacterial abundance) as a function of host size (length of average worker bee) and uncover a positive log-linear relationship in the corbiculates, whereby larger bees host more bacteria (Fig. 7C). Bacterial diversity itself does not correlate with either community size or bee size when comparing across all corbiculates (Fig. 7D and fig. S12; F test, P > 0.05). However, weak positive correlations are found when the corbiculate clades are considered separately (Fig. 7D and fig. S12; OLS) and when corrected for phylogeny (Fig. 7D and fig. S12; PGLS).
The peculiarities of host ecology may help explain these diversity patterns. Unlike honey bees and stingless bees, which grow by colony fission (46, 47), bumble bee colonies are founded by single queens (48), imposing potential bottlenecks on microbiota diversity. For yet unknown reasons, the Bombus gut microbiota also appears more prone to perturbation and displacement by environmental bacteria (19, 20, 49), and despite their larger body size, bumble bees often form colonies that are orders of magnitude smaller than those of Apis or the Meliponini (101 to 102 versus 103 to 104 individuals). Hence, the effective “habitat size” for Bombus-associated microbes may be considerably smaller than that for Apis or the Meliponini, leading to lower overall gut community diversity (Fig. 7A and fig. S11).
To test this hypothesis, consider that an analog to habitat size in such interconnected social systems may not simply be an individual bee but also the colony or the local host population among which microbes are shared among conspecific individuals. If this is true, bee species with larger colony sizes would be expected to have greater gut microbial diversity. In agreement, we find a strong correlation with gut community diversity when host bacterial load is adjusted by colony size (Fig. 8, A and B). Linear models suggest that both gut community size (or, collinearly, bee size) and colony size are significant predictors of gut microbiome diversity in the eusocial corbiculates (Fig. 8C and fig. S13).
Fig. 8 Large bee colony size is associated with higher microbiome diversity.
(A) Plot of microbiome diversity (number of OTUs at OTU97 clustering) against gut community size (16S rRNA gene copies) × bee colony size. (B) Plot of microbiome diversity (Shannon’s H at OTU99.5 clustering) against gut community size (16S rRNA gene copies) × bee colony size. Large dots, species averages; small dots, individual samples. Best-fit lines for different regression analyses are shown. (C) Linear modeling of the effects of gut community size (16S rRNA gene copies), host phylogenetic affiliation (tribe), and bee colony size on microbiome diversity (Shannon’s H at OTU99.5 clustering). Models that include an interaction of gut community size and bee colony size have the greatest relative likelihood. Goodness of fit between models was compared with likelihood ratio tests. See fig. S13 for linear model details.
DISCUSSION
Recent years have seen a proliferation of studies on gut communities in efforts to understand the microbiota’s role in the health and development of their animal hosts. However, scant attention has been paid to how the microbiota itself arises and evolves (50–53). The evolutionary context of a microbiome may reveal crucial insights not evident when focusing on a single host, but the complexity of most gut communities has thus far hindered this type of investigation. Here, we show that the corbiculate bees are a tractable system for studying changes in gut microbiota composition across a clade’s evolutionary history.
We find that the emergence of the eusocial corbiculate bees likely coincided with their acquisition of five core gut bacterial lineages, Snodgrassella, Gilliamella, Lactobacillus Firm-4, Lactobacillus Firm-5, and Bifidobacterium (Fig. 4B). This is supported by their widespread incidence in all three corbiculate groups examined (Fig. 2), as well as by deeply branching divergences marking host-specific clades in some of these bacteria, notwithstanding occasional host switching (Figs. 5 and 6A and figs. S8 and S10). These bacteria are largely absent in our outgroup bees, although the presence of trace levels of Snodgrassella and Gilliamella (Fig. 2) could represent occasional horizontal acquisition from corbiculate bees or environmental pools of related strains [for example, Gilliamella-related Orbaceae strains are found in other insects (54, 55)]. Gains of other bacterial lineages, as well as losses of existing ones, appear to happen with frequency. For instance, we identify a recurring Acetobacter-like OTU associated with many, but not all, Meliponini bees. This OTU also matches sequences recovered from African stingless bees (18), suggesting that this uncharacterized bacterium is affiliated with a breadth of stingless bee diversity but has been lost in some host lineages.
When explaining microbiota composition in extant corbiculate species, a variety of potential mechanisms should be considered. Although conspecific transmission of gut symbionts has been experimentally demonstrated in honey bees and bumble bees (12, 18), strict host-microbe codiversification is unlikely the norm. The gain of a gut symbiont in a host clade may have occurred more recently than in the last common ancestor, with the observed distribution resulting from promiscuous cross-host transfers rather than codivergence. Greater phylogenetic scrutiny at the strain level will help decipher the signatures of host switching, coevolution, and independent introductions, and their roles in shaping the dynamic corbiculate microbiome.
Regardless of the mechanistic details of these processes, the outcomes are divergent microbial communities most strongly distinguishable by host of origin (Fig. 3). Similar observations have been made in mammals and other social insects, where vertical inheritance is thought to play a large role in gut community assembly (8, 50, 52, 56, 57). It is also probable that, through both neutral and adaptive mechanisms, the microbiota differs between allopatric bee populations (11). However, given our sample sizes and level of phylogenetic resolution, we did not detect a strong effect of geographic location on microbiota composition or strain diversity (Fig. 3 and figs. S2, S3, S5, and S9B). An analysis of Snodgrassella and Gilliamella 16S rRNA gene sequences across Bombus and Apis hosts by Koch et al. (18) also found poor correlation with geography, with a small significant effect present only in Gilliamella.
Within host species, there are instances of variable prevalence of the core microbiota members, suggesting that particular hosts may be more prone to compositional shifts influenced by geography, colony of origin, food resources, or physiological status. This intraspecific variation seems to be more pronounced in bumble bees and in some species of stingless bees. For instance, Gilliamella was prevalent in Bombus bifarius from Utah, but not that from Colorado (Fig. 2), and there was differential presence of Snodgrassella and Parasaccharibacter in Tetragonula carbonaria between two collection sites (data file S2). Similarly, a previous survey of Australian stingless bees found that microbiomes differed between colonies (58).
Compared to Apis and Bombus, the stingless bee microbiome appears to span a much greater range of possible states, being highly variable in composition, richness, and evenness (Figs. 2, 3A, and 7, and figs. S1 and S2). Perhaps not coincidentally, the Meliponini are also the most diverse of the corbiculate groups, comprising ~500 species in ~50 genera (59, 60) compared to ~9 in Apis and ~250 in Bombus (48). The variability found in the Meliponini microbiota may be an evolutionary hallmark of their hosts’ correspondingly diverse life histories, morphologies, and behaviors (60). A fourth corbiculate tribe, the Euglossini (orchid bees), contains species with differing degrees of social organization, from solitary to communal (61), but their microbiomes remain uncharacterized.
Host sociality facilitates the development of heritable microbial communities by providing a semiclosed system with reliable transmission routes between host “islands” of similar environments. There is evidence for this in some clades of primates, rodents, and ants (8–10, 62), but asocial hosts, such as Drosophila (55, 63), generally lack characteristic gut microbiotas unless particular adaptations are adopted (for example, maternal transmission and environmental filtering) (64, 65). Long-term, transgenerational habitat stability becomes a suitable backdrop against which microbial specialists can evolve to best exploit emergent niches. For example, the transition to sociality in the wood roaches/termites enabled the development of a nutritionally specialized gut microbiota and a shift from an omnivorous to a wood-based diet (7, 66, 67). The corbiculate bee microbiota also appears to be metabolically optimized toward its host’s diet, with symbiont lineages such as Gilliamella, Lactobacillus, and Bifidobacterium able to enzymatically break down and ferment the sugars found in pollen, honey, and nectar (37, 39, 43, 68, 69). Other gut bacteria have specialized to particular physical locations, including Snodgrassella, which occupies the gut wall of the ileum (70); Frischella, which colonizes a small section of the pylorus (71); and Parasaccharibacter, which is found in relative abundance in larval food and worker hypopharyngeal glands (72).
In addition to opening up new niches for novel bacterial lineages, a stable gut habitat may promote strain-level diversification within existing community members by fostering large bacterial population sizes through which diversity can be maintained (73). The degree to which this diversity is functional or neutral is unknown (37, 74), but strain-level variants are common features of gut communities (38, 75). In animals and plants, taxon richness is often a function of habitat size, as modeled by the species-area relationship S = c × Az or S = log(c × Az), where S is a measure of diversity (for example, species or OTU richness), c is a constant particular to the system in question, A is the habitat size, and z is the correspondence between S and A (slope in log space) (45).
This relationship has been observed in some free-living microbial systems (76–78) but has been largely ignored for gut microbiomes, partly due to the lack of a direct analog to the habitat size metrics (for example, area) used for macroorganisms. Gut volume has been considered (79), as has body weight, as in a previous study that found no relation between microbiota diversity and weight of host individuals within a single bumble bee species (80). Here, we compare across corbiculate bee species and find a weak correlation with microbiota diversity by using absolute community size or bee size as proxies for habitat size (Fig. 7D and fig. S12). However, these proxies are incomplete: In social organisms, individuals are constantly exchanging microbes such that, if we wish to compare between host species, a meaningful habitat scale is likely larger than the gut of any individual. A more accurate measure would take into account host characteristics (for example, colony size, migration, degree of social interactions, and bottlenecking effects) so that the time-averaged suitable habitat for a microbial community to evolve within is approximated—a “nominal habitat size.”
We find support for this idea by showing that the inclusion of bee colony size as an explanatory factor greatly improves the correlation with microbiome diversity (Fig. 8 and fig. S13). Hence, we propose that a species-area relationship for host-associated microbiomes may be expressed as S = c × Hz, where nominal habitat size (H) is proportional not only to the metrics of individual hosts (for example, body size) but also to the particular characteristics of the host species. If such a relationship holds, then a better understanding of host biology, including life history and population structure, will be a key component toward explaining ecological patterns in gut microbial communities. Larger H may increase microbial population sizes, decreasing extinction and maintaining neutral variation, or give rise to allopatric diversification due to incomplete mixing and emergence of novel niches (81). However, we note that habitat size itself may only be one of many forces that influence the observed trends and may not be the factor that is most directly responsible. Further work will be needed to uncover the underlying mechanisms that drive microbial species-area relations and to help unite a long-standing macroecological concept with microbiome biology.
Although not examined in this study, the social nature of the corbiculates also presents opportunities to investigate the effect of caste (82, 83) and differing social organizations (84) on microbiome composition. Sociality alone is not enough for the establishment of host-specific microbiotas, as exemplified by the lack of consistent microbiomes in some clades of ants and bees (8, 84, 85). Measuring the contributions of additional factors, such as behavior and diet, will be necessary to better understand the evolution of persistent host-microbe associations.
Other fundamental yet understudied aspects of microbial ecology and evolution (51, 53, 86) await examination from the perspective of gut communities. For example, it is unclear what barriers prevent the spread of generalist strains into bees that have more specialized microbiomes (Fig. 6). Interaction between the microbiota and foreign invaders, such as parasites, and disease states is another area that remains poorly understood (87, 88). A major advantage of the corbiculate bee microbiome is its amenability to experimental hypothesis testing using cultivated strains and microbiota transplants. Together with a relatively low complexity compared to mammalian systems (22, 89), this makes the study of microbiome evolution in bees a feasible endeavor, with the potential to provide novel insights into the symbiotic gut communities of social animals.
CONCLUSION
We collected bees at multiple sites across four continents. A small, recurring set of bacteria was found across the eusocial corbiculates, including within the previously sparsely sampled stingless bees. Microbiome composition strongly aligned with host identity, more so than with geographic origin, and closely related hosts had more similar microbiomes. We show that bee microbiome evolution is dynamic, with multiple gains and losses of bacterial lineages; nonetheless, a core corbiculate community exists, the acquisition of which coincides with the origin of eusociality. Within bacterial lineages, strain-level diversity is common and mostly host-specific. How this host specificity is maintained is unclear, but we are able to test hypotheses, such as host incompatibility and interbacterial competition, using in vivo microbiota transplant experiments.
There are large-scale patterns in bee gut community diversity. For instance, we discovered that bumble bee microbiomes are less diverse and more erratic in composition than those of honey bees. Microbiome diversity was weakly correlated with gut community size and bee size and more strongly associated with bee colony size. These findings indicate that host ecology drives large-scale trends in microbiome diversity and that a form of species-area relationship may be applicable to gut communities.
Overall, this study offers evidence that vertical inheritance, through social contact, is a major force that shapes the corbiculate bee microbiome over the clade’s evolutionary history. Our results support the emerging hypothesis that host sociality facilitates the development and maintenance of specialized microbiomes by providing favorable ecological conditions and reliable transmission mechanisms.
MATERIALS AND METHODS
Specimen collection and identification
Adult worker bees were obtained from sites across seven countries (Australia, Malaysia, Singapore, Hong Kong, South Korea, United States, and Brazil), mostly between May 2013 and October 2014 (data file S1). Specimens were kept in 100% ethanol or frozen at −80°C for DNA preservation. For a subset of samples, the guts were removed, homogenized, and then frozen in 19% glycerol, allowing for preservation of live bacteria from which strains were later isolated.
Of the approximately nine recognized Apis species, the five most common species were collected. Both the Neotropical and Indo-Malay/Australasia clades of the diverse stingless bees (90) were sampled, including species used in commercial meliponiculture such as Heterotrigona itama, Geniotrigona thoracica, and T. carbonaria (91, 92). Bumble bees were collected from sites in the United States (Colorado, New Jersey, Texas, and Utah) and included new samples and samples from the study of Powell et al. (93). As outgroups for comparative analyses, we obtained specimens of C. atripes [tribe Centridini, a close relative of the corbiculates (94)] and A. abrupta [tribe Anthophorini, which is a more distant outgroup but still belongs to the “Apine line” of subfamily Apinae (95)]. Where available, sympatric bees were collected at the same time and location.
Bee species were identified by morphology. For most stingless bee samples, the mitochondrial 16S rRNA gene was also sequenced, following Rasmussen and Cameron (90). For C. atripes and A. abrupta, the 28S rRNA gene was sequenced, following Martins et al. (94). Sequences were classified on the basis of the closest BLAST hits in the GenBank nonredundant (nr) database (data file S1). To verify that samples classified as the same species were related, phylogenies based on their sequences were built and inspected in Geneious R9 (Biomatters Ltd.).
DNA extraction
DNA was extracted with a protocol adapted from Powell et al. (12). Entire guts were removed from bee abdomens and crushed in 100 μl of CTAB buffer [0.1 M tris-HCl (pH 8.0), 1.4 M NaCl, 20 mM EDTA, and cetrimonium bromide (20 mg/ml)], resuspended in a total of 728 μl of CTAB buffer and 20 μl of proteinase K [20 mM tris-HCl, 1 mM CaCl2, 50% glycerol, and proteinase K (20 mg/ml)], and transferred to a capped vial containing 500 μl of 0.1-mm Zirconia beads (BioSpec Products Inc.). 2-Mercaptoethanol (2 μl) and 2 μl of RNase A cocktail (Invitrogen Corp.) were added, and samples were bead-beated for 3 × 2 min. Samples were digested overnight at 50°C before the addition of 750 μl of phenol/chloroform/isoamyl (25:24:1, pH 8.0). Samples were mixed and centrifuged for 15 min at 4°C and 20,000g. The aqueous layer was removed, and the DNA was precipitated at −20°C for 0.5 hours with 700 μl of isopropanol and 70 μl of sodium acetate (pH 5.3). Precipitated samples were spun at 4°C at 20,000g for 30 min, and the supernatant was decanted. DNA pellets were washed with −20°C ethanol and spun for an additional 5 min at 4°C. The ethanol wash was removed by pipetting, and the DNA pellets were dried at 50°C and then resuspended in 50 μl of water. Final DNA samples were stored at −20°C.
16S rRNA gene amplification and sequencing
Extracted DNA samples were quantified fluorometrically (Qubit, Thermo Fisher Scientific Inc.) and then diluted to 10 ng/μl for use as PCR template. For all Bombus samples and samples prefixed with “WKsample” (data file S1), Illumina barcoded primers, designed according to Caporaso et al. (96), were used to amplify a 291–base pair (bp) fragment encompassing the V4 region of bacterial 16S rRNA. Triplicate 25-μl reactions were run for 25 to 30 cycles of amplification at an annealing temperature of 65°C, using 1 μl of DNA template and the NEBNext DNA Library Prep Master Mix according to the manufacturer’s protocols. The PCR products were cleaned using AxyPrep Mag PCR Cleanup (Axygen Scientific Inc.) with 0.8× volume of beads to remove primer dimers. Samples were pooled to equimolar concentration and sequenced on the Illumina MiSeq 2 × 250 bp platform with primers Read1F (5′-TATGGTAATTGTGTGCCAGCMGCCGCGGTAA), Read2R (5′-AGTCAGTCAGCCGGACTACHVGGGTWTCTAAT), and Index (5′-ATTAGAWACCCBDGTAGTCCGGCTGACTGACT).
For samples prefixed with “A” (data file S1), the Illumina Nextera kit was used for library preparation of V4 region amplicons generated with the adapter-primer pairs Hyb515F_rRNA (5′-TCGTCGGCAGCGTCAGATGTGTATAAGAGACAGGTGYCAGCMGCCGCGGTA) and Hyb806R_rRNA (5′-GTCTCGTGGGCTCGGAGATGTGTATAAGAGACAGGGACTACHVGGGTWTCTAAT), using the above amplification protocol; these were then sequenced on the Illumina MiSeq 2 × 250 bp platform. The two primer sets are designed to amplify 251 and 252 bp (excluding primer sequence), corresponding to the V4 region of Escherichia coli 16S rRNA, which completely overlap save for 1 bp at the 5′ end. All sequencing was performed at the University of Texas Genomic Sequencing and Analysis Facility.
Reads were demultiplexed on the basis of the barcode sequences, allowing for one mismatch. Control samples using purified DNA from E. coli K12 or a synthetic bee gut community, composed of G. apicola wkB1, S. alvi wkB2, and Lactobacillus Firm-5 wkB8, were included in each sequencing run. Between 2313 and 80,286 reads were acquired for each sample.
16S rRNA–based gut community analysis
Demultiplexed reads were processed on the QIIME 1.9.1 pipeline (97). The following scripts were run sequentially: join_paired_ends.py with the SeqPrep option to join forward and reverse reads; split_libraries_fastq.py for quality filtering set at phred q ≥ 30, maximum N = 0, and read length fraction minimum of 0.8; and read_length_filter.py to retain only reads between 230 and 270 bp (expected read length of ~250 bp after primer trimming).
For 97% OTU clustering (OTU97), pick_de_novo_otus.py was used with default settings (uclust algorithm) and taxonomy assignment based on the Silva119 reference database (98). Sequences were then checked for chimeras with ChimeraSlayer in QIIME 1.9.1. Each sample was further filtered to remove OTUs that comprise ≤0.5% of reads (due to potential misassigment of barcodes between samples during multiplexed sequencing). Each sequence comprising this final set of representative OTU97 sequences was then manually checked by BLAST against the GenBank nr database to refine taxonomic assignment (data file S2).
For 99.5% OTU clustering (OTU99.5), de novo OTU picking was done with pick_otus.py and pick_rep_set.py using default settings (uclust algorithm). Singleton OTUs were filtered out, as were samples with read depths of less than 5000. Remaining samples were then rarefied to 5000 reads. OTU99.5 taxonomy was assigned with parallel_assign_taxonomy_blast.py using the manually refined taxonomy from OTU97 as reference. Representative sequences from OTU97 16S rRNA clustering were deposited in GenBank (data file S4), and representative sequences from OTU97 and OTU99.5 clustering are presented in data file S5.
To determine relative abundance and prevalence of bacterial taxa in Fig. 2, nonbacterial OTUs were removed from the OTU97 table, and remaining OTUs were removed from the OTU97 table, and remaining OTUs were subsumed into broader categories based on phylogenetic relatedness (see data file S2). In Fig. 3 and fig. S2, PCoA ordinations on binary Sørensen-Dice dissimilarities of samples at the OTU97 clustering were determined in QIIME 1.9.1. To test for group similarities, ANOSIM using 999 permutations was performed in QIIME 1.9.1. The ANOSIM test statistic R indicates group similarity, where 0 = indistinguishable and 1 = dissimilar. NMDS ordinations on the Sørensen-Dice dissimilarity matrices were generated with the metaMDS function in the “vegan” package for R v.3.2.2 (99, 100).
Diversity metrics (number of unique OTUs, Shannon’s H, and Shannon’s E) were calculated in QIIME 1.9.1 (Fig. 7 and figs. S11 and S12). At OTU99.5 clustering, Shannon’s H is superior to OTU counts as a measure of diversity because clustering at this level results in OTU count inflation from sequencing errors; Shannon’s H places less weight on low-abundance (potentially erroneous) OTUs. To test for diversity differences between groups (Fig. 7A and fig. S11), nested ANOVA was conducted in R v.3.2.2, with species as subgroups. To test for differences in group variation (Fig. 7B), Levene’s test in the “car” package for R v.3.2.2 was used (101). Worker size (length in millimeters) and bee colony size represent mean of size ranges reported in the literature (table S1).
Absolute bacterial quantification
A subset of samples (data file S1) was selected for quantification of 16S rRNA gene copy number, as a proxy for the number of bacteria present per bee gut. qPCR using universal bacterial 16S rRNA gene primers was performed as in the work of Cariveau et al. (19). Standards were cloned into pGEM-T Easy vector (Promega Corp.), linearized with Apa I, and fluorometrically quantified before generation of standard curves.
Ancestral microbiome reconstruction
To estimate the changes in microbiome composition over corbiculate bee evolution (Fig. 4B), a presence/absence matrix of Snodgrassella, Gilliamella, Lactobacillus Firm-4, Lactobacillus Firm-5, Bifidobacterium, B. apis, Frischella, Bombiscardovia, Schmidhempelia, and the Acetobacter-like OTU was mapped against the host phylogeny (cladogram). Taxa with <1% abundance and <20% prevalence (Fig. 2) were considered absent. Gains and losses across host lineages were determined by asymmetrical Wagner parsimony in Count v.10.04 (102) with gain and loss penalties of 1.5 and 1, respectively.
The true phylogeny of the corbiculate bees and related taxa is not well resolved. Although the species relationships within Apis and Bombus and the reciprocal monophyly of Bombini and Meliponini are generally accepted, the relationships within the Meliponini, as well as the placement of the Euglossini with respect to the other three corbiculate tribes, are contentious (103). The host taxa relationships presented here (Figs. 4 and 5) were obtained by joining the results of multigene phylogenies within Apis (104), Bombus (105, 106), and the Meliponini (90), together in a supertree based on their most highly supported relations with each other and with the outgroups (94, 103, 107). For bee species that were not included in these previous studies, placement was based on that of their respective genera. Because these data sources are not directly comparable, phylogenetic distances were omitted from these analyses.
Microbiome dissimilarity and host relatedness
The impact of host phylogeny on microbial community dissimilarity was investigated using a Mantel test of correlation between matrices of pairwise Sørensen-Dice dissimilarities and host divergences in the “vegan” package in R v.3.2.2 with 104 permutations (99). Because phylogenetic distances or divergence times were not available for our sampled bee species, a nodal distance approach based on the work of Webb (108) was used, whereby the number of nodes separating bee species on our tree (Fig. 4B) was counted as a proxy for host divergence. Although this method only gives a relative measure of divergence and is subject to sampling bias effects (108), it enables analysis with a tree topology that is consistent with that of published reports.
We performed partial Mantel tests to determine the correlation between microbiome dissimilarity and host phylogeny while controlling for geography and the correlation between microbiome dissimilarity and geography while controlling for host phylogeny. A geographic distance matrix generated from sample collection locations was used; 104 permutations were run for each analysis.
Linear models testing
To further examine the contributions of geography and host identity on microbiome composition (fig. S5), linear mixed-effects models were generated with the lmer function in the “lme4” package for R v.3.2.2 (109). The NMDS coordinates of each sample (fig. S3A) were used as proxies for microbiome composition. “Locations” were designated as collection sites within approximately 15-km-radius regions. To test for the contributions of host identity, host body size, bee colony size, and microbiota community size on microbiome diversity (fig. S13), linear models were generated with the lm function in R v.3.2.2. Bee body sizes and colony sizes were obtained from literature sources (table S1). Samples where diversity values (number of OTUs97, Shannon’s H) or bee colony size information were not available were excluded from the analysis. Optimal model selection using Akaike’s Information Criterion was performed with the model.sel function in the “MuMIn” package for R v.3.2.2 (110). The goodness of fit between alternative models was tested with the ANOVA likelihood ratio test in R v.3.2.2.
To account for the effects of phylogenetic nonindependence in comparisons of species-level covariates (Figs. 7, C and D, and 8 and fig. S12), PGLS analyses were conducted in addition to OLS tests. The bee phylogeny was obtained as described above, with all internal and terminal branches set at equal lengths. The packages “ape” (111), “geiger” (112), “nlme” (113), and “phytools” (114) for R v.3.2.2 were used to construct and test PGLS models with the gls function under a Brownian motion model of evolution (λ = 1).
Phylogenetic analysis of Lactobacillus Firm-5 and Snodgrassella alvi
To obtain greater phylogenetic resolution of the Lactobacillus Firm-5 group, two conserved single-copy genes were cloned and sequenced. The gene encoding ribosomal polymerase α subunit, rpoA, was amplified with primers wk121 (5′-GAATTTGAAAAACCAAATATTACCG) and wk122 (5′-CGTACACGCATCATATCTGC), whereas the gene encoding translation elongation factor Tu, tuf, was amplified with wk123 (5′-GAACAAAGCCACACGTAAAC) and wk124 (5′-GACCAGCACCAACAGTACGA). These produced products of 815 and 1103 bp, respectively. Primers were designed to be specific for Firm-5 sequences, on the basis of existing genomes for this clade (42, 43), and for other Lactobacillus species (115).
For S. alvi, tuf was amplified with primers wk135 (5′-TGGCTAAAGAAAAATTCGAGCGG) and wk136 (5′-AAGCGATAACTTTAGCAACCACAC), producing a 1141-bp amplicon. There are two tuf copies in S. alvi genomes.
PCRs were carried out using Phusion polymerase (New England Biolabs Inc.) and the following cycling conditions: initial denaturing at 98°C for 30 s; 30 cycles at 98°C for 10 s, at 60°C for 20 s, and at 72°C for 30 s; and a final extension at 72°C for 2 min. PCR products were cleaned using AxyPrep Mag PCR Cleanup (Axygen Scientific Inc.), A-tailed with Taq polymerase (New England Biolabs Inc.), and cloned into pGEM-T Easy vector (Promega Corp.). The resulting plasmids were electroporated into E. coli DH5α, and colonies carrying inserts were identified by blue-white screening. Cloned inserts were sequenced by the Sanger method using vector-specific primers T7 and SP6.
Forward and reverse sequences were assembled, and ambiguities were manually corrected in Geneious R9 (Biomatters Ltd.). A total of 184 and 55 MUSCLE-aligned tuf sequences were used for Firm-5 and S. alvi phylogenetic analysis, respectively (figs. S7 and S8). Appropriate models of evolution were determined using jModelTest2 (116). Phylogenies based on Bayesian inference were produced with MrBayes 3.2 (117) using GTR+gamma+inv for each codon position, a run-time of 2 × 107 generations with tree sampling every 1000 generations, and a burn-in of 0.25. Convergence of Bayesian Markov chain Monte Carlo runs was assessed with AWTY (118). For maximum likelihood analyses, the GTR+gamma+inv model was used for each codon position in RAxML v8 (119) with 1000 bootstrap replicates. For Lactobacillus Firm-5 rpoA (fig. S9A), a total of 46 MUSCLE-aligned sequences were used to build phylogenies as above, except a 2 × 106 generation run-time with tree sampling every 500 generations was used in the Bayesian analysis.
Isolation of gut symbiont strains
Frozen glycerol stocks of homogenized guts were plated out on heart infusion agar or Columbia agar supplemented with 5% sheep’s blood (Hardy Diagnostics) and incubated at 35°C and 5% CO2 for 3 to 7 days. Colonies were screened by colony PCR to identify S. alvi, using primers described in previous studies (14, 18). Follow-up sequencing of 16S rRNA genes using the universal primers 27F and 1492R was used to confirm the identity of isolates (54).
Colonization and competition assays
S. alvi strains isolated from A. mellifera (wkB2, wkB332), A. cerana (wkB298), A. florea (wkB273), A. andreniformis (wkB237), and Bombus bimaculatus (wkB12) were used to colonize laboratory-reared A. mellifera. Approximately 102 cells were fed to germ-free, newly emerged workers; after 5 days, CFUs were counted, as in Kwong et al. (39).
For competition assays, germ-free, newly emerged A. mellifera workers were co-inoculated with two strains of S. alvi, as described by Kwong et al. (39). Bees were fed ~106 cells in 1:1 ratios of strains derived from A. mellifera (wkB2 or wkB332) and those from other Apis species. To determine the effect of the initial dosage on strain competitiveness, ratios of 1:10 and 10:1 were also used in a subsequent assay between wkB2 and wkB298/wkB273. Strains were differentiated by transferring colonies onto blood heart infusion agar plates with tetracycline (25 μg/ml). Strains wkB2 and wkB332 are tetracycline-resistant, whereas the other strains are susceptible. Count data are presented in table S2.
Supplementary Material
http://advances.sciencemag.org/cgi/content/full/3/3/e1600513/DC1
Acknowledgments
We thank D. Cariveau (Rutgers University), J. P. Strange (United States Department of Agriculture, Logan, Utah), L. Lach (James Cook University), R. Gloag (University of Sydney), T. Heard (Commonwealth Scientific and Industrial Research Organisation, Australia), J. J. Wilson (University of Malaya), J. X. Q. Lee (Singapore), the Po Sang Yuen Bee Farm (Hong Kong), and A. Kwong (Hong Kong) for providing samples, reagents, and/or advice for this project. In addition, we thank E. Frederick for technical assistance and J. E. Powell and N. Ratnayeke for Bombus data. Funding: This work was supported by Yale University, the Yale University Department of Ecology and Evolutionary Biology Chair’s Fund, the Sigma Xi Grants-in-Aid of Research, and the Canadian Natural Sciences and Engineering Research Council Postgraduate Scholarship (to W.K.K.); the Swiss National Science Foundation Postdoctoral Fellowship (140157 and 147881 to H.K.); Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP 2012/13200-5 and 2013/23661-2 to R.J.); and the U.S. National Science Foundation Dimensions of Biodiversity (awards 1046153 and 1415604 to N.A.M.). Author contributions: W.K.K. conceived the study, designed sampling and experiments, conducted sampling, performed experiments, analyzed data, and wrote the paper. L.A.M. isolated bacterial strains and performed experiments and qPCR. H.K., K.-W.S., E.J.Y.S., J.S.A, and R.J. designed and conducted sampling. N.A.M. advised on study design, provided samples and reagents, and wrote the paper. All authors participated in manuscript revisions. Competing interests: The authors declare that they have no competing interests. Data and materials availability: Sequences from bee identification, phylogenetic analysis of rpoA and tuf genes, and OTU97 16S rRNA clustering are deposited under GenBank accession numbers KU571725 to KU572279 (data file S4). Raw 16S rRNA gene amplicon reads are deposited in the National Center for Biotechnology Information Sequence Read Archive under accession SRP071118. All other data needed to evaluate the conclusions in the paper are present in the paper and/or the Supplementary Materials. Additional data related to this paper may be requested from the authors.
SUPPLEMENTARY MATERIALS
Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/3/3/e1600513/DC1
fig. S1. Absolute bacterial abundance per bee gut, as measured by 16S rRNA gene copies.
fig. S2. Gut community similarities, compared using PCoA of binary Sørensen-Dice dissimilarities at OTU97 clustering.
fig. S3. NMDS plots of gut community Sørensen-Dice dissimilarities at OTU97 clustering.
fig. S4. UPGMA clustering of communities based on Sørensen-Dice and unweighted UniFrac distances.
fig. S5. Linear mixed models testing of the effects of sampling location and host identity on microbiome composition.
fig. S6. Ancestral microbiome reconstructions using parsimony for the major corbiculate bacterial phylotypes.
fig. S7. Bayesian phylogeny of Lactobacillus Firm-5 based on the tuf gene.
fig. S8. Maximum likelihood phylogeny of Lactobacillus Firm-5 based on the tuf gene.
fig. S9. Phylogeny of Lactobacillus Firm-5 based on rpoA, and geographic associations of strains.
fig. S10. Tanglegram of host bee and Lactobacillus Firm-5 phylogenetic topologies.
fig. S11. Gut microbial diversity, as measured by Shannon’s H on OTUs clustered at 99.5% similarity.
fig. S12. Relationships between bee body size, gut community size (16S copies), and microbiome diversity.
fig. S13. Linear models testing of the effects of bee body size, gut community size (16S copies), host phylogenetic affiliation (tribe), and bee colony size on microbiome diversity.
table S1. Bee size and colony size estimation and literature sources.
table S2. Snodgrassella co-inoculation trials count data.
data file S1. List of samples and associated metadata used in this study.
data file S2. OTU97 tables and curated taxonomic assignments.
data file S3. OTU99.5 tables summarized by bacterial taxa, from samples rarefied to 5000 reads.
data file S4. List of sequences deposited in GenBank.
data file S5. Representative sequences from OTU97 and OTU99.5 clustering.
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Sci AdvSci AdvSciAdvadvancesScience Advances2375-2548American Association for the Advancement of Science 28435858160095510.1126/sciadv.1600955Research ArticleResearch ArticlesSciAdv r-articlesBioengineeringFlexible and stretchable nanowire-coated fibers for optoelectronic probing of spinal cord circuits Lu Chi 12*Park Seongjun 23*Richner Thomas J. http://orcid.org/0000-0001-6230-14644Derry Alexander http://orcid.org/0000-0003-2076-11841Brown Imogen 5Hou Chong http://orcid.org/0000-0002-1975-074712Rao Siyuan http://orcid.org/0000-0002-1555-487X2Kang Jeewoo http://orcid.org/0000-0002-1439-26026Moritz Chet T. 4Fink Yoel 127Anikeeva Polina 12†1 Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.2 Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.3 Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.4 Departments of Rehabilitation Medicine and Physiology and Biophysics, Center for Sensorimotor Neural Engineering, UW Institute for Neuroengineering, University of Washington, Seattle, WA 98195, USA.5 Department of Materials, University of Oxford, Oxford OX1 3PH, UK.6 Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.7 Advanced Functional Fabrics of America Inc., 500 Technology Square, NE47-525, Cambridge, MA 02139, USA.* These authors contributed equally to this work.
† Corresponding author. Email: anikeeva@mit.edu3 2017 29 3 2017 3 3 e160095501 5 2016 10 2 2017 Copyright © 2017, The Authors2017The AuthorsThis is an open-access article distributed under the terms of the Creative Commons Attribution-NonCommercial license, which permits use, distribution, and reproduction in any medium, so long as the resultant use is not for commercial advantage and provided the original work is properly cited.Stretchable optoelectronic fibers interrogate spinal cord circuits during free behavior.
Studies of neural pathways that contribute to loss and recovery of function following paralyzing spinal cord injury require devices for modulating and recording electrophysiological activity in specific neurons. These devices must be sufficiently flexible to match the low elastic modulus of neural tissue and to withstand repeated strains experienced by the spinal cord during normal movement. We report flexible, stretchable probes consisting of thermally drawn polymer fibers coated with micrometer-thick conductive meshes of silver nanowires. These hybrid probes maintain low optical transmission losses in the visible range and impedance suitable for extracellular recording under strains exceeding those occurring in mammalian spinal cords. Evaluation in freely moving mice confirms the ability of these probes to record endogenous electrophysiological activity in the spinal cord. Simultaneous stimulation and recording is demonstrated in transgenic mice expressing channelrhodopsin 2, where optical excitation evokes electromyographic activity and hindlimb movement correlated to local field potentials measured in the spinal cord.
Keywords
spinal cordneural probesfibersflexible optoelectronicsnanowiresoptogeneticshttp://dx.doi.org/10.13039/100000084Directorate for EngineeringID0EH3EK15763EEC-1028725Anikeeva Polina http://dx.doi.org/10.13039/100000146Division of Chemical, Bioengineering, Environmental, and Transport SystemsID0EXEFK15764CBET-1253890Anikeeva Polina http://dx.doi.org/10.13039/100000078Division of Materials ResearchID0EHNFK15765DMR-1419807Anikeeva Polina http://dx.doi.org/10.13039/100006955Office of Extramural Research, National Institutes of HealthID0EXVFK157665R01NS086804Anikeeva Polina http://dx.doi.org/10.13039/100006754U.S. Army Research LaboratoryID0EH5FK15767W911NF-13-D-0001Fink Yoel http://dx.doi.org/10.13039/100004358SamsungID0EZCGK15768FellowshipPark Seongjun http://dx.doi.org/10.13039/100000084Directorate for EngineeringID0EHJGK15769EEC-1028725Moritz Chet T Washington Research Foundation InnovationID0EFNGK15770Postdoctoral fellowshipRichner Tom http://dx.doi.org/10.13039/100000078Division of Materials ResearchID0E24GK15771DMR-1419807Fink Yoel CopyeditorEarl Rosopa
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INTRODUCTION
Traumatic injuries to the spinal cord are frequently associated with loss of organ function or loss of voluntary limb control. Our understanding of and ability to treat these symptoms is currently limited by the tools available for monitoring and manipulating neural dynamics within the spinal cord. Because of the relative ease of genetic manipulation, rodent models have become indispensible discovery tools for basic neuroscience. Optogenetic modulation of genetically identifiable neuronal populations in rodent spinal cords may enable discovery of the neural pathways crucial for recovery following injury. However, the spinal cord’s viscoelastic modulus of 0.25 to 0.3 MPa (1) poses engineering challenges to the design of optoelectrophysiological probes. Furthermore, repeated spinal cord deformations during normal movement demand resilience of the implantable devices to bending and extension fatigue.
Inspired by preclinical (2) and early clinical (3, 4) studies indicating the promise of spinal stimulation to facilitate rehabilitation following paralyzing injury, recent work has focused on flexible and stretchable probes for optical and electrical stimulation on the surface of rodent spinal cords (5, 6). The ability to perform neural recording during stimulation may similarly be essential to elucidate the electrophysiological origins of functional recovery. Furthermore, devices suitable for implantation deep within the spinal cord may permit interrogation of specific interneurons, isolating their functional contributions to loss and recovery of connections following injury. Here, we report flexible and stretchable probes that combine optical stimulation with electrophysiological recording that can be implanted into the mouse spinal cord. We adopt a thermal drawing process to produce polymer fibers, and then coat these devices with micrometer-thick meshes of conductive silver nanowires (AgNWs). We characterize electrical impedance and optical transmission of these probes during deformations commonly occurring in rodent spinal cords, thereby illustrating the resilience of the polymer fiber cores and concentric mesh electrodes to strain. Electrophysiological recording of spontaneous, sensory-evoked, and optically evoked neural activity in the spinal cords of mice expressing channelrhodopsin 2 (ChR2) further illustrates the promise of these hybrid fiber probes for studies of spinal cord circuits. Recording of endogenous activity in freely moving mice chronically implanted with fiber probes in their spinal cords, combined with analysis of the surrounding tissue, suggests minimal disruption to local neural networks.
RESULTS
Design and fabrication of the nanowire-coated fiber probes
To fabricate probes suitable for electrophysiological recording and optical neuromodulation in rodent spinal cords, we combined two techniques. First, we used thermal drawing to produce a flexible optical fiber that also served as a structural core for the probe (Fig. 1A). Being versatile and scalable, thermal drawing can be applied to macroscale templates (preforms) composed of multiple materials. It also allows us to reduce final device dimensions by up to 200 times (fig. S1) while producing hundreds of meters of fiber in a single draw (Fig. 1B) (7, 8). By tuning the stress during the drawing process, a range of feature dimensions can be achieved without compromising the cross-sectional geometry defined within the preform (fig. S1).
Fig. 1 Fabrication of flexible neural probes.
(A) Illustration of the fiber probe fabrication. (B) Spool of a fiber with PC core and COC cladding. (C) Transmission electron microscopy (TEM) image of the AgNWs. (D) Cross-sectional image of the fiber probe. (E) Scanning electron microscopy image shows a portion of the ring AgNW electrode cross section. (F) Scanning electron microscopy image of the AgNW mesh on top of the fiber surface.
On the basis of previous work applying multimaterial fibers to optical neuromodulation (9, 10), polycarbonate (PC; refractive index n = 1.58; glass transition temperature Tg = 145°C; Young’s modulus E = 2.38 GPa) and cyclic olefin copolymer (COC; n = 1.52, Tg = 158°C, E = 3.0 GPa) were selected as the respective core and cladding of the optical fiber (11–13). To enable neural recording while minimizing the device footprint, we deposited uniform 1-μm-thick conductive layers of AgNWs (diameter d = 70 nm; length L = 40 μm) (Fig. 1, A and C) over the COC cladding via dip coating from isopropanol (IPA) solutions with different concentrations (Fig. 1, A, D to F). Because the hydrophobicity of COC limited the adhesion and deposition of AgNWs from IPA (14), oxygen plasma treatment of the fibers was essential to enhance the uniformity of AgNW mesh layers (14, 15). An AgNW coating was chosen as the electrode material because of its high conductivity and compatibility with facile solution-based processing (16). It was hypothesized that the mesh formed by AgNWs would be more resilient with respect to bending and stretching deformation (17, 18) than a continuous metallic film of comparable thickness, because the latter is anticipated to develop cracks under strains commonly experienced in spinal cords (19). The entire structure was then encapsulated within a layer of polydimethylsiloxane (PDMS; n = ~1.41 to 1.47; thickness, 5 μm) (20) to minimize direct contact of AgNW with tissue and prevent surface oxidation and mechanical degradation (Fig. 1, A and D). The final device diameter ranged from 105 to 135 μm and was constrained by the dimensions of the structural fiber core (100 to 130 μm).
Optical and electrical properties of the nanowire-coated fiber probes
To match the mechanical properties of neural tissues, flexible polymer-based optical waveguides have been recently introduced to replace conventional rigid silica fibers (21–27). Waveguides composed of SU-8 and poly(methyl methacrylate) (PMMA) fabricated via a lithographic process have been used in the context of optogenetic neuromodulation (23), whereas PDMS and hydrogel-based devices have been applied to fluorescence measurements and optical control of gene expression (20, 26, 27). In addition to their transparency across the visible spectrum (fig. S2), the polymers PC and COC are compatible with the thermal drawing process. Consequently, the geometry of the device can be easily altered to fit the application (28). The difference between the refractive indices of PC and PDMS is 0.18. Although this should, in principle, be sufficient to sustain multimode transmission through the fiber even in the absence of COC cladding (fig. S2), direct coating of AgNWs onto the PC surface resulted in significant losses due to scattering and evanescent coupling of light into the plasmon modes of these nanomaterials (Fig. 2A) (29). Addition of the COC cladding reduced the losses from 2.5 to 1.9 dB/cm (Fig. 2A). Because of their flexibility, these probes were able to maintain transmission under extreme deformations (Fig. 2B), including their use as sutures (Fig. 2C).
Fig. 2 Optical characterization of flexible neural probes.
(A) Normalized transmission at a wavelength λ = 473 nm as a function of length for fiber probes with and without COC cladding to separate AgNW mesh from the PC optical core with a diameter of 120 μm. (B) Transmission at λ = 473 nm for PC/COC/AgNW/PDMS fiber probes (core diameter, 120 μm) bent at 90° or 180° as radii of curvature (0.5 to 10 mm) displayed relative to straight probes. All scale bars and shaded areas represent SEM. n = 5 samples for each data point. (C) Image of a PC/COC/AgNW/PDMS fiber probe connected to a laser source, threaded through a needle, and used to create several stitches on fabric.
Electrophysiological recording during optogenetic neuromodulation is commonly accomplished by integrating conductive electrodes within the probes (23, 30–34). Conductive polymer composites exhibit high flexibility and biocompatibility (35), but are limited by high impedances on the order of megohms (9, 10, 36). Metallic electrodes deposited on polymer substrates have low impedance but are subject to cracking (19). Fractal and serpentine metallic electrodes defined via contact printing address the flexibility challenge but offer limited spatial resolution (5, 6, 37–39). AgNW meshes were previously used as stretchable interconnects in flexible electronic applications (16), and their composites have been recently applied to monitoring of cardiac function (35). We found that to reproducibly achieve meshes with low resistivity, the concentration of AgNWs in a dip-coating solution needed to exceed 4 mg/ml. At concentrations >6 mg/ml, the resistivity of the AgNW mesh was proportional to the concentration of the dip-coating solution (Fig. 3A). To account for anticipated changes in mesh morphology during deformation, we chose the lowest resistance mesh (9.37 × 10−4 ohm∙cm) for our probes. PDMS was selected as a protective coating for the conductive layer because of its low modulus (tens of kPa for 30:1 polymer to curing agent by weight) and low refractive index, ensuring confinement of light to the PC/COC core (40). Following dip coating with PDMS, the probe tips were cut orthogonally to the fiber axis, exposing thin conductive AgNW ring electrodes. Similar to solid metallic electrodes, the impedance of the probes at 1 kHz had a significant dependence on the contact area but less on the length. Mesh electrodes within 1- and 10-cm fiber probes exhibited impedance values of similar orders of magnitude (|ZPC/COC, 1 cm| = 50 ± 26 kΩ, |ZPC/COC, 10 cm| = 58 ± 21 kΩ; mean ± SEM), which indicated that, following evaluation in small rodents, this fabrication approach may, in principle, be scaled to applications in larger animals (Fig. 3B).
Fig. 3 Electrical characterization of flexible neural probes.
(A) Resistivity of the mesh as a function of AgNW solution concentration. Inset: TEM images of the AgNW meshes deposited from solutions with 2, 6, and 10 mg/ml concentrations. AgNW mesh deposited from the 10 mg/ml solution was used for further characterization and in vivo evaluation. (B) Impedance spectra of the AgNW mesh electrodes deposited on 1-, 5-, and 10-cm-long fibers with 120-μm PC/COC cores. All scale bars and shaded regions represent SEM. n = 5 samples for each data point.
In addition to bending, AgNW mesh concentric electrodes were also resilient to stretching deformation. Using a fabrication process identical to the one outlined for PC/COC fibers, we thermally drew stretchable fibers composed of COC elastomer (COCE; n = 1.51; melting temperature Tm = 84°C; E = 34 MPa). We chose COCE because of its low modulus and compatibility with a range of drawing parameters. To establish stable processing conditions, we introduced sacrificial PMMA cladding into the preform and then removed it with acetone following drawing (Fig. 4). The resulting pillow-shaped COCE fibers (cross-section width × height in the range from 125 μm × 100 μm2 to 250 μm × 200 μm2) were similarly treated with oxygen plasma, dip-coated with AgNWs, and encapsulated with PDMS. Consistent with lower optical transmission of COCE as compared to PC and COC, higher optical losses of 3.98 dB/cm were measured for AgNW-coated COCE core fibers (fig. S3).
Fig. 4 Mechanical and electrical characterization of stretchable neural probes.
(A) Tensile tests performed for a thermally drawn COCE fiber and a COCE fiber probe coated with three layers of AgNW mesh and a protective PDMS cladding (COCE/AgNW/PDMS) (n = 5 devices). (B) Impedance spectra of the AgNW mesh electrodes deposited onto 200 × 200 μm2 COCE core fiber with lengths of 1, 5, and 10 cm. (C) Impedance of a three-layer AgNW mesh within COCE/AgNW/PDMS probes with core dimensions of 200 × 200 μm2 as a function of tensile strain. (D) Scanning electron microscopy images of the three-layer AgNW mesh deposited onto COCE fiber at 0, 10, and 20% strain. (E) Impedance of fiber probes characterized in (C) measured over five extension and release cycles. All scale bars represent SEM. n = 5 samples for each data point.
Because COCE is a rubbery material, these fibers could sustain up to 230% strain, which was reduced to 200% following the coating with AgNWs and PDMS (Fig. 4A). AgNW mesh electrodes coated onto 1- and 10-cm COCE fibers exhibited somewhat greater difference in impedance (|ZCOCE, 1 cm| = 34 ± 17 kΩ, |ZCOCE, 10 cm| = 162 ± 50 kΩ; mean ± SEM; Fig. 4B), as compared to their PC/COC analogs. However, the absolute values of impedance were still well within the range suitable for extracellular recordings even for 10-cm-long fibers.
We found that a single-layer AgNW mesh coating could only withstand strains of ~30% before losing conductivity due to the disruption of the conductive network (fig. S4). In contrast, electrodes composed of a three-layer AgNW mesh maintained low impedance at strains up to ~100% (Fig. 4C). This is consistent with scanning electron microscopy images that do not reveal any structural differences between the AgNW mesh–coated fibers subjected to 0, 10, and 20% strain (Fig. 4D). Repeated extension of the COCE/AgNW/PDMS fibers resulted in negligible hysteresis of the electrode impedance, indicating resilience of these devices to deformation (Fig. 4E). Because the spinal cord and peripheral nerves only experience strains up to ~12% (41), the low-impedance AgNW mesh–coated fibers provide arbitrarily scalable and stretchable alternatives to polymer composite and metallic electrodes.
In vivo electrophysiological recording and optical stimulation with nanowire-coated fibers
We evaluated the ability of the AgNW-coated fibers to record and optically stimulate neural activity in the mouse spinal cord (Fig. 5, A and B). Optoelectronic fibers with PC/COC and COCE optical cores were implanted into the lumbar region (L1) of the spinal cord of WT and Thy1-ChR2-YFP transgenic mice that broadly express light-sensitive cation channel ChR2 (42). Acute experiments in anesthetized mice indicated the ability of both PC/COC and COCE fiber probes with AgNW electrodes to record spontaneous neural activity (Fig. 5, C to F, and fig. S5). Single-neuron signals were isolated (Fig. 5, D and F) and assessed by principal components analysis (fig. S5, A and C) and interspike interval (ISI) histograms (fig. S5, B and D).
Fig. 5 Probing spinal cord electrophysiology with flexible and stretchable neural probes.
(A) Schematic depicting optical stimulation and electrophysiological recording with a fiber probe in a mouse spinal cord. (B) Image of mouse implanted with a flexible neural probe between L1 and L2 exploring its environment. (C) Spontaneous activity recorded in acute conditions with AgNW concentric mesh electrodes deposited onto PC/COC core fibers in spinal cord of wild-type (WT) mice. (D) Action potentials isolated from the recording in (C). (E) Spontaneous activity recorded in acute conditions with AgNW concentric mesh electrodes deposited onto COCE core fibers. (F) Action potentials isolated from the recording in (E). (G) Sensory-evoked potentials recorded acutely from the dorsal column with AgNW mesh electrodes within PC/COC-based probes at different input currents (1 to 8 mA; 125 μs per phase biphasic). Sensory potentials are preceded by the electrical stimulus artifact. (H) Sensory-evoked potential (SEP) recruitment curve relating the area under the first positive peak to the stimulus amplitude. (I) Neural activity in a spinal cord of a Thy1-ChR2-YFP mouse evoked by optical stimulation (wavelength λ = 473 nm, 168 mW/mm2, 5-ms pulse width, 10 Hz) delivered through the PC/COC fiber and recorded with the concentric AgNW mesh electrodes. (J) Neural activity in spinal cord of a Thy1-ChR2-YFP mouse evoked by optical stimulation (wavelength λ = 473 nm, 125 mW/mm2, 5-ms pulse width, 10 Hz) delivered through the COCE fiber and recorded with the concentric AgNW mesh electrodes. (K) EMG evoked by the optical stimulation in (J). (L) Optically evoked local field potentials recorded with AgNW mesh electrodes within COCE fiber. (M) An expanded view of the averaged EMG signal from (K).
Electrophysiological activity was also recorded with AgNW electrodes within PC/COC- and COCE-based fiber probes in tethered, freely moving WT mice up to 1 week following the implantation surgery (fig. S6). Recordings from freely moving mice contained a combination of multiunit activity and movement artifacts and were confounded by greater noise levels than those performed under anesthesia. However, the noise level remained stable over these week-long studies. In addition to spontaneous activity, we recorded robust sensory-evoked potentials from the dorsal columns that scaled with current applied to the ipsilateral hind foot (Fig. 5, G and H, and fig. S7, A and B).
In Thy1-ChR2-YFP mice, illuminating the lumbar region of the spinal cord with laser light (125 to 168 mW/mm2) with a wavelength λ = 473 nm (activation peak of ChR2), coupled into fiber cores through ferrules, consistently evoked neural activity that was correlated with the 5-ms optical pulses at 10 Hz (latency, 10.6 ± 0.5 ms) (Fig. 5, I and J). Stimulation at a higher frequency of 100 Hz similarly evoked neural activity (fig. S8). However, in this case, the observed multineuron potentials did not follow each laser pulse, consistent with ChR2 kinetics (43). Neural activity in the lumbar spinal cord induced by optical pulses delivered through the fiber probes was sufficient to produce muscle contractions in the ipsilateral hindlimb (Fig. 5, K and M, fig. S9, and video S1). The electromyographic (EMG) activity recorded in a gastrocnemius muscle (Fig. 5M) was correlated with the optically evoked local field potentials recorded with the AgNW mesh–coated COCE fibers in the lumbar spinal cord (Fig. 5L).
Immunohistochemical analysis of the spinal cord tissue surrounding the fiber probes indicated modest astrocytic presence, as indicated by staining with antibodies against glial fibrillary acidic protein (GFAP), for the devices positioned on the surfaces and within the tissue 2 weeks after the implantation surgeries (fig. S10). Furthermore, the depth probes reaching into the gray matter did not appear to interfere with the viability of the surrounding neuronal populations (fig. S10, D and E).
DISCUSSION
By combining thermally drawn polymer fibers with solution-deposited nanowires, we developed flexible and stretchable concentric probes suitable for optical and electrophysiological interrogation of spinal cord circuits in the mouse model. Our devices maintained optical and electrical properties under bending and stretching deformations, exceeding those experienced by the mouse spinal cord during normal motion. The mechanical, optical, and electrical characteristics of the probes enabled acute recordings of spontaneous neural activity, sensory-evoked potentials, and the simultaneous recording of optically evoked spinal potentials and optical control of hindlimb muscles. These findings suggest that the fiber platform may, in the future, permit monitoring and controlling of neural activity to promote recovery following spinal cord injury. Isolating single-neuron action potentials from the mouse spinal cord during free behavior remains a goal because such recordings are exceedingly difficult, having been rarely reported in rodents (44). Even in acute studies, the flexibility of our probes may provide a solution to the challenges associated with the recording of neural activity in the spinal cord posed by the respiration and heartbeat, which often necessitate a transection of nerves leading to the diaphragm (45).
Our conceptual experiments conducted with AgNW meshes as electrodes within fiber probes do not reveal tissue erosion or cytotoxic effects in the vicinity of the implants (fig. S9). These nanomaterials were chosen as an affordable alternative to gold NWs. Going forward, any metallic NWs can be similarly deposited onto polymer fiber surfaces, further enhancing long-term biocompatibility and tunability of charge-carrying capacity (46). Additional chemical stability can be achieved through covalent cross-linking of the mesh (47), and the surface of the exposed NW ring can be passivated through electrodeposition of gold or iridium oxide layers via established protocols routinely applied to nickel-chromium (Ni/Cr) tetrodes (48).
AgNW mesh electrodes enabled straightforward integration of electrophysiological recording capability into polymer optical fibers without significant increase in overall device dimensions. In the future, the number of channels can be expanded by integrating multiple concentric NW rings separated by thin elastomer coatings and by patterning the mesh electrode surfaces, for example, through the use of photosensitive PDMS (49, 50). The high surface area of exposed NWs, as compared to monolithic electrodes of similar cross section, may permit maintaining impedance values in the range applicable for extracellular recordings, even following patterning of the meshes. The probes demonstrated here relied solely on scalable fiber drawing and solution-based fabrication methods that do not pose constraints on device dimensions or geometry. Acting as flexible and stretchable optical canvases for electrophysiological probes, these fibers may, in the future, be tailored to address fundamental questions in spinal cord or visceral organ neurophysiology.
MATERIALS AND METHODS
Fiber probe fabrication
PC/COC waveguide
To fabricate a preform, we wrapped a PC cylinder (diameter, 9 mm; McMaster-Carr) in COC sheets (thickness, 0.05 mm; TOPAS Advanced Polymers, 6015S) to the total preform diameter of 12.5 mm. The entire structure was then consolidated at 190°C for 12 min in vacuum. The fiber was drawn at 280°C, and the drawing speed was varied from 1 to 7 m/min to achieve draw-down ratios in the range of 30 to 140.
COCE rubbery fiber
To fabricate the preform, we first cast-molded pellets of COCE (TOPAS Elastomer E-140) into rectangular strips (L = 100 mm, W = 6 mm, H = 6 mm) at 180°C in vacuum. PMMA (thickness, 12.7 mm; McMaster-Carr) plates were machined into two 25.4 mm-wide strips, followed by machining grooves in the center of each strip and filling those with molded COCE. The preform was then consolidated under pressure (50 psi at 125°C) for 14 hours and cooled to room temperature while concomitantly reducing the applied stress. The preform was drawn at 240°C, and the resulting fiber dimensions were reduced 40 to 80 times.
The fiber probes were connected to zirconia ferrules (Thorlabs, CF128) using optical epoxy (Thorlabs, F112). The ferrule ends of the fibers were then polished with silicon-carbide sandpaper.
Electrode fabrication and connection
The surface of the fiber probe was treated with oxygen plasma, dipped into IPA solution of AgNWs (10 mg/ml, Novarials NovaWire-Ag-A70-IPA), and dried in the air for at least 3 hours. Copper wire (AWG-38) was placed on the fiber surface, attached with a conductive silver paint (SPI Supplies, 04998AB), and then dried in the air for 2 hours. The AgNW-coated fibers were dipped into PDMS (Sylgard 184, Dow Corning; 30:1 polymer to curing agent by weight) and cured at 70°C for 1 hour. The joint between the fiber probe and the copper wire was sealed with epoxy (Devcon, 5 Minute Epoxy) to enforce the connection. The copper electrode lead was then connected to a four-pin connector (Digi-Key ED90528-ND) for electrophysiological data acquisition. Before implantation, the fiber probes were coated with molten poly(ethylene glycol) (molecular weight, 1000) to temporarily stiffen them for implantation.
Fiber probe characterization
Optical loss coefficients (in dB/cm) were measured by connecting fiber probes of different lengths to a fiber-coupled 473-nm blue laser (Laserglow Technologies) via ferrule-to-ferrule connection with zirconia sleeves (Thorlabs, ADAF1) and by collecting the power output with a calibrated silicon photodiode (Thorlabs, S121C and PM100D).
Tip impedances of AgNW electrodes were measured in saline solution (0.9 wt %) with an LCR meter (Agilent 4284A) (10 mV) in a frequency range of 0.1 to 1000 kHz. Tensile tests were performed using a nano tensile tester (MTS Nano Instrument UTM390).
Structural and surface analysis with microscopy
Scanning electron microscopy images were collected using a Zeiss Ultra-55 microscope (4 kV). TEM was performed on a FEI Tecnai G2 Spirit TWIN (120 kV). Optical images were obtained using Zeiss Axioskop 2 MAT microscope with ×10 magnification.
In vivo studies
All procedures involving vertebrate animals were approved by the Massachusetts Institute of Technology (MIT) Committee on Animal Care. No additional ethical guidelines were considered. Fiber probes were evaluated in male Thy1-ChR2-YFP transgenic (donated by G. Feng) and WT (BL6/57, The Jackson Laboratory) mice housed at the MIT central animal facility (12-hour light/dark cycle at 22°C with food and water ad libitum).
Fiber implantation
The AgNW- and PDMS-coated PC/COC and COCE fiber probes were acutely and chronically implanted into the lumbar region of the spinal cord of Thy1-ChR2-YFP and WT mice. The mice were anesthetized using isoflurane (5% induction followed by 1.75 to 2.0% in oxygen). Supplemental heat was provided during the surgery. The fur was removed over the dorsum, and the skin was cleaned with alcohol and povidone iodine. One midline incision was made over vertebral segments T13, L1, and L2. The paraspinal muscles were removed to expose the vertebrae. Lateral spinal clamps were used to hold L1 in a stereotaxic frame (Kopf, model 980). The spinal cord was exposed between L1 and L2 by further dissection. The neural probe was placed on the surface of the dorsal side of spinal cord and then lowered by 300 μm into the spinal cord. For chronic implantation, the three segments were fused with dental cement (Metabond, Parkell). This step was omitted during acute experiments. The probes were connected to the neural recording headstage and the optical patch cord (details below) and then lowered into the spinal cord using a stereotaxic manipulator. A low-impedance ground/reference wire (stainless steel) was coiled and placed next to the vertebral column. For chronic implantation, gelfoam was deposited around the probe tips, and the probes were secured with dental cement to the three fused vertebral segments. The mice were dosed with slow-release buprenorphine analgesia and recovered on a warm pad.
Optical stimulation
Laser pulses were applied through the COCE and PC/COC fiber cores to the spinal cord. A blue laser (diode-pumped solid-state; 473 nm, 100 mW; Laserglow) was coupled to a fiber patch cord [diameter, 50 μm; numerical aperture (NA), 0.22; silica; Thorlabs] with a custom two-mirror setup on an optical breadboard. The patch fiber was coupled to a fiber probe using a ferrule-to-ferrule ceramic sleeve. The laser was controlled by the neural recording setup (Tucker-Davis Technologies, RZ5D) to produce pulse trains of 1-s duration with 5-ms pulses applied at 10 or 100 Hz. Optical power of 2.5 mW was measured at the probe tip, leading to a power density of 125 to 168 mW/mm2 at the surface of the spinal cord.
Electrophysiological recordings in the spinal cord
Spontaneous and stimulus-evoked potentials were recorded using AgNW mesh electrodes within the PC/COC- and COCE-based probes. The mesh electrodes were connected to a high-impedance headstage (Tucker-Davis Technologies, ZIF-Clip 32) through a custom PCB adapter board. The signals were sampled at 48 kHz (PZ2, Tucker Davis Technologies) and filtered (0.3 to 10 kHz; third-order infinite impulse response) in Matlab (MathWorks). Single-neuron action potentials (spikes) were isolated by detecting threshold crossings at 2 SDs from the noise level, projecting the spikes onto the first two principal components, and then clustering with k-means. ISI histograms were calculated from the sorted units.
Electromyography
EMG signals were recorded from the gastrocnemius muscle with two polytetrafluoroethylene-coated stainless steel wires [A-M Systems; diameter, 50 μm/115 μm (bare/coated)]. The 1-mm tips of the wires were exposed using a scalpel to reduce impedance before insertion into the muscle belly with a 25-gauge needle. The EMG signals were amplified by the high-impedance headstage and sampled at 48 kHz. Single-ended recordings relative to a low-impedance distant reference and ground were collected from each electrode. These recordings were low pass–filtered (25th-order finite impulse response; 5-kHz corner frequency) and subtracted in Matlab to produce a differential recording.
Sensory-evoked potentials
Sensory-evoked potentials were recorded from the dorsal columns of anesthetized WT mice using AgNW mesh electrodes on PC/COC cores. Electrical stimuli were applied peripherally to the ipsilateral hindlimb. Two stainless steel wires, identical to those described in the EMG section above, were inserted subcutaneously near the ankle. One wire was placed medial to the ankle, and one wire was placed lateral. Biphasic current pulses (125 μs per phase, 1 to 8 mA) were delivered every 2 s. The resulting volley of activity was recorded at the dorsal columns with the AgNW electrodes. The experiment was repeated after flipping the polarity of the biphasic pulse as a control. An adaptive filter was applied to remove power-line noise without introducing impulse response artifacts near the stimulus. The area under the first positive peak was integrated at each stimulus level to create a recruitment curve. The curve was fit to a sigmoid using a weighted least-squares regression on a positive range (Matlab).
Immunohistochemistry
Long-term tissue responses to the fiber probes implanted over and within the spinal cords were investigated by immunohistochemistry. Two weeks after implantation with PC/COC/AgNW/PDMS or COCE/AgNW/PDMS probes, WT mice (n = 3 per device) were anesthetized via intraperitoneal injection of Fatal-Plus solution (100 mg/kg in saline) and perfused with 4% paraformaldehyde (PFA) in phosphate-buffered saline (PBS). Spinal cords were extracted and fixed in 4% PFA overnight, and then sliced into 50-μm coronal sections using a vibrating blade microtome (Leica VT1000S). Sections were permeabilized and blocked in 0.3% (v/v) Triton X-100 and 3% (v/v) donkey serum in PBS for 30 min. This was followed by overnight incubation at 4°C in a solution of primary antibodies (goat anti-GFAP, 1:1000; rabbit anti-NeuN, 1:500; Fisher Scientific) and 3% donkey serum in PBS. Following incubation, the sections were washed three times for 30 min each with PBS. The slices were then incubated with secondary antibodies (Alexa Fluor 488 donkey anti-goat, 1:1000; Alexa Fluor 633 donkey anti-rabbit, 1:1000; Life Technologies) for 1 hour at room temperature. Following three more washes with PBS, slices were mounted using PVA-DABCO (Sigma-Aldrich) onto glass microscope slides. A laser-scanning confocal microscope (FluoView FV1000, Olympus) with 10× (air, NA = 0.16) objective was used for image acquisition.
Supplementary Material
http://advances.sciencemag.org/cgi/content/full/3/3/e1600955/DC1
Acknowledgments
C.L. is grateful to M. J. Tarkanian and I. Feitler for their assistance with machining. Funding: This work was supported by the Center for Sensorimotor Neural Engineering, an NSF Engineering Research Center (EEC-1028725), NSF CAREER award to P.A. (CBET-1253890), NSF Center for Materials Science and Engineering (DMR-1419807, IRG-I), the National Institute of Neurological Disorders and Stroke (5R01NS086804), the U.S. Army Research Laboratory, and the U.S. Army Research Office through the Institute for Soldier Nanotechnologies (W911NF-13-D-0001). This work made use of facilities at the Center for Nanoscale Systems at Harvard University, which is a member of the NSF National Nanotechnology Infrastructure Network (ECS-0335765). S.P. is a recipient of Samsung Scholarship, and T.J.R. is a Washington Research Foundation Innovation Postdoctoral Fellow with the UW Institute of Neuroengineering. Author contributions: C.L. and P.A. designed the experiments. C.L., A.D., I.B., C.H., and S.R. fabricated and characterized fiber probes. C.L. performed mouse surgeries. C.L., S.P., T.J.R., and P.A. performed electrophysiological experiments and analyzed the data. C.L., S.P., J.K., and P.A. performed immunohistochemistry and analyzed the data. C.T.M. facilitated with the design of in vivo evaluation experiments. Y.F. aided with the design of fiber-based probes. All authors took part in the preparation of the manuscript. Competing interests: The authors declare that they have no competing interests. Data and materials availability: All data needed to evaluate the conclusions in the paper are present in the paper and/or the Supplementary Materials. Additional data may be requested from the authors. Physical samples of the fiber probes are available upon request.
SUPPLEMENTARY MATERIALS
Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/3/3/e1600955/DC1
fig. S1. Controlled parameters during the drawing of the PC/COC fiber.
fig. S2. Optical transmission spectra of PC/COC fibers at visible wavelengths.
fig. S3. Transmission at a wavelength λ = 473 nm for COCE fiber.
fig. S4. Impedance of COCE fibers coated with a single layer of AgNW mesh and measured at 0, 10, and 20% extension strain.
fig. S5. Spontaneous single units isolated during acute anesthetized recordings (see Fig. 5, C to F).
fig. S6. Electrophysiological recording collected from the freely moving mice implanted with fiber probes.
fig. S7. Additional in vivo sensory and electromyographic recordings.
fig. S8. Electrophysiological recordings of optically stimulated activity.
fig. S9. In vivo EMG recordings.
fig. S10. Immunohistochemical analysis of the dorsal horn 2 weeks after device implantation surgeries.
video S1. Optical spinal control of muscle activity.
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Sci AdvSci AdvSciAdvadvancesScience Advances2375-2548American Association for the Advancement of Science 28435868160304410.1126/sciadv.1603044Research ArticleResearch ArticlesSciAdv r-articlesBiophysicsLabel-free optical detection of single enzyme-reactant reactions and associated conformational changes Kim Eugene *†Baaske Martin D. *†Schuldes Isabel †‡Wilsch Peter S. http://orcid.org/0000-0002-4395-8919†Vollmer Frank *§Max Planck Institute for the Science of Light, Staudtstrasse 2, 91058 Erlangen, Germany.* Corresponding author. Email: eugene.kim@mpl.mpg.de (E.K.); martin.baaske@mpl.mpg.de (M.D.B.); f.vollmer@exeter.ac.uk (F.V.)† These authors contributed equally to this work.
‡ Present address: Chair for Crystallography and Structural Physics, University of Erlangen-Nuremberg, Staudtstrasse 3, Erlangen, Germany.
§ Present address: Living Systems Institute, School of Physics, University of Exeter, Exeter EX4 4QD, U.K.
3 2017 29 3 2017 3 3 e160304405 12 2016 09 3 2017 Copyright © 2017, The Authors2017The AuthorsThis is an open-access article distributed under the terms of the Creative Commons Attribution-NonCommercial license, which permits use, distribution, and reproduction in any medium, so long as the resultant use is not for commercial advantage and provided the original work is properly cited.Single-molecule enzyme-reactant interactions and the linked conformational changes are monitored via an optical microcavity sensor.
Monitoring the kinetics and conformational dynamics of single enzymes is crucial to better understand their biological functions because these motions and structural dynamics are usually unsynchronized among the molecules. However, detecting the enzyme-reactant interactions and associated conformational changes of the enzyme on a single-molecule basis remains as a challenge to established optical techniques because of the commonly required labeling of the reactants or the enzyme itself. The labeling process is usually nontrivial, and the labels themselves might skew the physical properties of the enzyme. We demonstrate an optical, label-free method capable of observing enzymatic interactions and associated conformational changes on a single-molecule level. We monitor polymerase/DNA interactions via the strong near-field enhancement provided by plasmonic nanorods resonantly coupled to whispering gallery modes in microcavities. Specifically, we use two different recognition schemes: one in which the kinetics of polymerase/DNA interactions are probed in the vicinity of DNA-functionalized nanorods, and the other in which these interactions are probed via the magnitude of conformational changes in the polymerase molecules immobilized on nanorods. In both approaches, we find that low and high polymerase activities can be clearly discerned through their characteristic signal amplitude and signal length distributions. Furthermore, the thermodynamic study of the monitored interactions suggests the occurrence of DNA polymerization. This work constitutes a proof-of-concept study of enzymatic activities using plasmonically enhanced microcavities and establishes an alternative and label-free method capable of investigating structural changes in single molecules.
Keywords
single enzyme dynamicssingle molecule reactionconformational changepolymeraseprotein-DNA interactionsoptical microcavitywhispering Gallery modehttp://dx.doi.org/10.13039/501100004189Max-Planck-GesellschaftID0EWGBG17316MPRG VollmerVollmer Frank CopyeditorNova Morabe
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INTRODUCTION
Enzymes fulfill a plethora of metabolic functions in all living organisms. In many cases, enzymatic activity is closely connected to changes in the enzymes’ conformation often involving the transition through multiple substates. One of the most important and, perhaps, most studied enzymes is DNA polymerase, which is present in all cells and responsible for replicating genetic information. Outside of the actual metabolisms, it is used for important biological applications, such as polymerase chain reaction (PCR) and DNA sequencing. The enzymatic activity of DNA polymerase involves multiple steps, such as the binding of primer-hybridized template DNA, insertion of a deoxynucleoside triphosphate (dNTP), and incorporation of dNTP, thereby extending the strand by 1 nucleotide (nt). Each step of such a catalytic process is accompanied by conformational changes of the DNA polymerase. These transitions, together with the corresponding reaction pathways, have an intrinsically transient nature and have been vastly studied via single molecule–based techniques. The most widely used method is perhaps single-molecule Förster resonance energy transfer (FRET), which resolves the dynamics of DNA/polymerase interactions and the associated structural changes by measuring distances between labels attached to specific polymerase domains or DNA strands (1–5). Despite its great contribution to the extension of knowledge on the reaction mechanisms of DNA polymerase, this method intrinsically requires chemical modification of the enzyme to attach labels; hence, it can cause the studied enzyme to deviate from its natural kinetics. Inherent physical processes, such as photobleaching and large background signals, also limit the applicability of FRET (6). As a result, there is a great demand for label-free methodologies that can potentially broaden the scope of single-enzyme studies and complement the information obtained using label-based methods.
Here, we establish a label-free optical sensor platform capable of monitoring the kinetics and conformational dynamics of single enzymes, thus extending our previous bulk-sensing approach (7). We show that the kinetics of single-molecule DNA/polymerase (sm-DNA/Pol) interactions and the related conformational transitions of the polymerase can be studied using plasmonically enhanced whispering gallery mode (WGM) microcavity sensors (8–15). Our sensor recognizes conformational changes and the motion of single enzymes as shifts of the cavity’s optical resonance wavelength induced by the perturbation of the highly localized electric field at the tips of nanorods (NRs). The magnitude and sign of these shifts are proportional to the change in the electric field intensity integrated over the volume of the molecule. For an increasing (decreasing) integrated intensity, the induced resonance shift is toward longer (shorter) wavelengths. This can be applied for the study of molecular kinetics as follows. When a molecule enters the enhanced electric near field in the vicinity of the NRs, it causes a spectral red shift with an increasing magnitude as it moves toward the field’s intensity maximum. This is followed by a blue shift with the same magnitude when the molecule moves away from the NRs and leaves the near field completely. This concept also holds true when a molecule that is immobilized on the NRs changes its shape (that is, conformational state) in such a manner that the change in the volume-integrated field intensity is sufficient to cause recognizable spectral shifts of the WGM’s position in either direction. Here, we use these mechanisms to probe sm-DNA/Pol interactions with two different approaches: immobilization of DNA on the NRs for the study of sm-DNA/Pol interaction kinetics and immobilization of polymerase on the NRs for the observation of specific conformational transitions accompanied by its interaction with DNA molecules. In both cases, the statistical analysis of our sensor’s signals allows us to discern the different activity levels of three polymerase species: the Klenow fragment of Escherichia
coli DNA polymerase I (KF) and DNA polymerases from Thermus aquaticus (Taq) and Pyrococcus furiosus (Pfu). We also study the sm-DNA/Pol interaction kinetics and associated conformational changes with respect to the type of DNA [primer/template DNA (ptDNA) and single-stranded DNA (ssDNA)], temperature, and the presence of dNTPs.
Results and Discussion
Method for monitoring single-molecule DNA/polymerase interactions
The experimental setup used for monitoring interaction kinetics between polymerase and DNA is depicted in Fig. 1A. A fused silica microsphere with a diameter of ~80 to 100 μm serves as a WGM resonator and is placed inside a liquid sample cell made of polydimethylsiloxane. A Peltier element, which is attached to the wall of the sample cell, allows for temperature regulation of the liquid. WGMs are excited via frustrated total internal reflection of a wavelength-tunable laser beam (λc ≈ 642 and 780 nm) focused on the surface of a prism. The resonance wavelengths of WGMs are then determined from the transmission spectra obtained by sweeping the laser wavelength with a frequency of 50 Hz using a modified centroid method (14).
Fig. 1 Methods for the detection of sm-DNA/Pol interactions.
(A) Schematic of the prism-based microcavity sensor setup. The inset shows an image of NR scatterers bound to the equatorial plane of a microsphere. (B) Typical transmission spectra showing a WGM (Lorentzian dip) before (blue) and during (red) a DNA/polymerase interaction. (C) Conceptual representation of the two different approaches used for monitoring DNA/polymerase interactions (immo-DNA and immo-Pol scheme) and (D) the corresponding resonance traces, exhibiting spike signals caused by the respective DNA/polymerase interactions.
Single-molecule sensitivity can then be achieved by using the plasmonic near-field enhancement provided by gold NRs, whose longitudinal surface plasmon resonances match the laser’s wavelength (12–17). For this, the NRs are immobilized on the resonator (see Methods for the chemical protocols) in a directly monitored process, allowing one not only to count the number of deposited NRs but also to determine if their long axes are aligned reasonably parallel to the polarization of the electric field via the binding-induced linewidth broadening and wavelength shifts of the monitored WGM (section S1). The local perturbations of the electric field near the NRs, as induced by sm-DNA/Pol interactions, can then be recognized as shifts Δλ in the spectral position of WGMs (Fig. 1B). As aforementioned, the magnitude and sign of these shifts are proportional to the changes in the electric field intensity integrated over the volume occupied by the molecule vm(t) at the times t1 and t2 = t1 + Δt (where Δt = 20 ms is the time between two laser sweeps) and to the molecule’s polarizability in excess to the medium αe (assuming a constant and isotropic molecular polarizability) (9, 10, 18) Δλ∝αe(∫vm(t2)|E(r)|2dV−∫vm(t1)|E(r)|2dV)=αe(I(t2)−I(t1))=αeΔI(1) where E(r) denotes the unperturbed electric field in the absence of the polymerase. However, this does not consider that the process of sweeping the laser over the spectral range occupied by the resonant mode (indicated as λm in Fig. 1B) itself requires a certain time τm. Consequently, each experimentally measured volume-integrated intensity Iexp,k for the kth sweep of the laser originates from an averaging process Iexp,k=I¯k=(τm)−1∫t0t0+τmI(t)dt(2) where t0 is the time in which the excitation of the mode begins. As a result, the experimentally obtained shifts are Δλk∝αe(I¯k−I¯k−1)=αeΔI¯k(3)
Therefore, our sensor can only recognize molecular interactions that keep the analyte molecules confined temporally on the order of τm ≈ 200 μs and spatially within the plasmonic hotspots (that is, near the NR tips). Molecular processes shorter than τm but occurring repeatedly during τm can also be recognized but with reduced magnitudes, whereas one-time events shorter than τm (for example, freely diffusing analyte molecules near the hotspots) are unlikely to be recognized as their Īk is significantly lower (section S9) (14). To study the sm-DNA/Pol interactions, we take two approaches: The first approach (Fig. 1C, top) is based on the polymerase interacting with DNA strands immobilized on the NRs (henceforth referred to as the immo-DNA scheme). In this case, the shifts occur because of the changes in Ī as polymerase molecules are attached and detached from the DNA strands, consequently moving in and out of the areas with high field intensities (Fig. 2, A and D). For the second approach (Fig. 1C, bottom), the polymerase molecules are immobilized on the NRs (henceforth referred to as the immo-Pol scheme), and the observed shifts are caused by changes in Ī due to the polymerase changing its conformational states accompanied by its interaction with DNA strands (Fig. 2, B, C, and E). Using both approaches, we obtain similar transient signal patterns (so-called “spikes”) arising from the sm-DNA/Pol interactions (Fig. 1D). These are composed of an initial red shift of the resonance position as a molecular interaction starts and a consequent return to the unperturbed mode position (blue shift) as the interaction ceases. Each individual spike exceeding the wavelength noise σ by at least three times is found and extracted using a spike detection algorithm (14). This algorithm also removes background drifts and returns the average and maximum shifts (Δλ¯ and Δλmax, respectively) and the spike duration (Δτ). In line with the proofs of the single analyte nature demonstrated in our previous studies (13–15), we have found that the detected spikes from the sm-DNA/Pol interactions originate from a Poisson process, and their detection rates scale linearly with the analyte concentrations (section S2). However, we would like to note that the presented single-molecule proofs do not indicate that only one receptor molecule (the immobilized reactant) was monitored overall because the spikes can originate from an ensemble of receptor molecules immobilized on the NRs. Nonetheless, the statistical proof confirms that each individual spike originates from a single receptor interacting with a single analyte molecule, whereas previous or later spikes may originate from a different receptor.
Fig. 2 Near field–based transduction mechanism.
(A to C) Spatial distributions of the near field’s intensity and the parameters associated with the respective movement of the polymerase volume. (A) Distance between the NR and the polymerase. (B) Changing angle between both arms with fixed base. (C) Changing angle between both arms with fixed left arm. a.u., arbitrary units. (D and E) Dependence of the volume-integrated intensity I, normalized to Vm, on the parameters associated with (A) to (C).
To further elaborate on the sensor’s response, we have performed finite element simulations to obtain the near-field intensity I of the electric field in the proximity of NRs. For this, we used simplified geometry for the polymerase consisting of two moving arms and a stationary bottom with the size parameters obtained via x-ray crystallography (19). Specifically, we compare the changes in I that are associated with the movement of the polymerase (Fig. 2, A and D) as a correspondence to the immo-DNA scheme. For the immo-Pol scheme, the changes in I depending on the variations of angular spread between the thumb and the finger domain of the polymerase were compared at two different immobilization positions (Fig. 2, B, C, and E). The near-field intensity exhibits a highly inhomogeneous distribution within the volume of the polymerase and rapidly decays with increasing distance from the NR’s tip. Consequently, I decreases significantly as the gap Δd between the NR and the polymerase increases on the scale of a few nanometers (Fig. 2D). Furthermore, I generally increases as the angle θ between the two arms of the polymerase increases, whereas its absolute value and θ dependency largely vary for different immobilization locations (Fig. 2E). In addition, we observed that for a different bound position of the polymerase, an increment of the angle θ could also lead to a decrease in I. This indicates that the WGM shift induced by the same conformational change of the polymerase (that is, the same θ) can exhibit a different magnitude and a different sign of the shift. However, in the experiments, only the spikes toward longer wavelengths were observed (Fig. 1D).
Interaction kinetics of different DNA polymerase species
By using the immo-DNA approach (Fig. 1C, top), we experimentally inspect the interaction kinetics of two different polymerase species, Taq and KF, at a temperature (T) of ≈293 K. Both Taq and KF are expected to show apparent differences in their kinetic behavior because their enzymatic activity is optimal at distinctively different temperatures (Topt) of 348 to 353 K and 310 K, respectively. Representative resonance wavelength traces for both species are shown in Fig. 3A.
Fig. 3 sm-DNA/Pol interaction signals using immo-DNA scheme.
(A) Example resonance traces exhibiting spike patterns caused by Taq (top; blue) and KF (bottom; maroon) polymerase/DNA interactions and the different noise levels found for ptDNA-functionalized NRs (maroon), unfunctionalized NRs (green), and in the absence of KF (light blue). (B) Distributions of the average spike amplitudes Δλ¯ and (C) durations Δτ obtained for Taq (blue) and KF (red) interacting with ptDNA in the presence of dNTP. The concentrations of Taq, KF, and dNTP were kept to ≈200 nM, 200 nM, and 50 μM, respectively.
In the case of Taq, we do not observe any change in noise level associated with either the presence or the absence of Taq and ptDNA. However, as for KF, the noise level rises once KF is added and increases even further after DNA is immobilized on the NRs. The former noise increase may be attributed to the unspecific short and reversible attachment of KF to the NRs, whereas the latter might originate from KF interacting with ptDNA molecules bound to locations on the NRs with low field intensities. Distinct spikes are observed only if ptDNA is immobilized on the NRs and if Taq or KF is present in solution, thus confirming the specificity of the monitored sm-DNA/Pol interactions (section S3). Furthermore, the expected difference in the kinetic behavior of Taq and KF is directly evident by comparing the spike magnitude and duration distributions obtained for both species (Fig. 3, B and C). The spike amplitudes found for Taq/ptDNA/dNTP interactions exhibit an exponentially decaying distribution (Fig. 3B, top), with 53% of the events populating the first bin above the 3σ limit. In contrast, the spike amplitudes obtained for KF/ptDNA/dNTP interactions have a significantly broader distribution exhibiting a clear peak at Δλ¯c well in excess of 3σ (Fig. 3B, bottom). This stark difference in the distributions is, at first, surprising because one would expect higher spike amplitudes for Taq polymerase because of its larger molecular mass (98 kDa) compared to KF (68 kDa). However, the spike magnitude is the result of a temporal averaging process (Eqs. 2 and 3) and, therefore, should be seen in conjunction with the spike duration because events shorter than τm are recognized with a reduced shift magnitude. We find the spike durations Δτ associated with Taq/ptDNA interactions (Fig. 3C, left) to be significantly shorter than those originating from KF/ptDNA interactions (Fig. 3C, right). Correspondingly, both species also yield distinctively different off-rates (koff) of 47 and 23 s−1 [extracted via fitting of N(Δτ)~e−koffΔτ to the respective distributions]. The fact that the experiments were performed at 293 K, a temperature rather close to the optimal temperature for KF but well below that for Taq, indicates that there is a correlation between our sensor’s signal and the activity of the monitored enzyme. However, it is worthwhile to note that the off-rates, which are extracted from the Δτ distributions, require careful interpretation because they are not necessarily equivalent to the dissociation rates between ptDNA and the polymerase. They rather reflect how long the polymerase resides within the plasmonic hotspots (that is, a period for which the value of Ī is high enough to be recognized) while it interacts with a DNA strand. This means that Ī can drop below the recognition threshold before the actual DNA/Pol interaction has ended because the polymerase moves along the overhanging template strand and away from the NR’s surface. In addition, the polymerase will start its activity at the end of the primer strand, which is ≈8 nm away from the NR’s surface, thus not reaching the maximum possible field overlap (compare Fig. 2D). Consequently, our values for koff exceed the dissociation rates reported in other studies (2, 20, 21) by at least one order of magnitude because we recognize only a small fraction of the actual reaction process along the entire template strand. Thus, it is evident that by using the immo-DNA approach, the amount of information that is directly obtainable is limited, although it still allowed us to recognize differences in the interaction kinetics of KF associated with ssDNA and ptDNA/dNTP interactions (section S5). Hence, we use the approach of immobilizing the polymerase on the NRs (the immo-Pol scheme) in the following studies of sm-DNA/Pol interactions.
Conformational transitions of Pfu polymerase at various temperatures
The above results suggest a possible correlation between our sensor signal (namely, the spike amplitudes and durations) and the activity of the monitored enzymes. Nonetheless, it is challenging to precisely determine the physical process associated with the signals because conformational changes and the motion of the whole enzyme cannot be directly separated from the immo-DNA scheme. To exclude the polymerase motion’s contribution to the signals, we have performed experiments with polymerase immobilized on the NRs (immo-Pol scheme as shown in Fig. 2B). For this, we selectively use Pfu polymerase because it maintains its enzymatic activity even when immobilized on the NR surface. Experimental data confirming its activity and successful immobilization on the NRs are provided in sections S4 and S6.
While monitoring the sm-DNA/Pol interactions in this scheme, we recognize spike events similar to the ones observed using the previously discussed immo-DNA scheme. Furthermore, the rates at which these spikes occur exhibit a linear dependence on the ptDNA’s concentration (fig. S2A), whereas no spikes were recognized in the absence of ptDNA (fig. S3A, bottom) and when the NRs were not modified with Pfu polymerase, thus confirming that the spikes originate from individual ptDNA/Pol interactions.
To further elaborate on the mechanism behind these spikes, we also monitored DNA/Pol interactions for ptDNA strands with different lengths (section S7), which yielded no significant difference in the observed spike amplitudes despite a 3.3-fold increase in the ptDNA’s molecular mass. On the basis of this finding and together with the fact that the immobilized polymerase has a significantly larger volume (as compared to the ptDNA) and, in turn, occupies a larger fraction of the sensing volume (Fig. 2), we believe that the spike signals cannot solely originate from ptDNA molecules directly perturbing the field close to the NRs but may rather be induced by conformational changes of the ptDNA/Pfu complex accompanied by the initial incorporation of ptDNA. However, we would like to note that relating the patterns of individual spikes with transitions between specific conformational states is difficult because, in the current sensing scheme, even a single point inside one spike is the result of an averaging process over a period τm (Eq. 2), which may include multiple transitions between conformational substates.
The relation between the recognized spikes and the conformational changes of the Pfu polymerase is further supported by their temperature dependence. The conformational changes of the thermophilic Pfu polymerase are closely linked to its enzymatic activity, which, in turn, is dependent on the ambient temperature and reaches its maximum in the 345 to 348 K range. Thus, we study how the durations and magnitudes of the ptDNA triggered spike signals change as we stepwise increase the ambient temperature toward this range while dNTPs are present in solution (Fig. 4). With respect to the spike amplitude distributions, we find that with increasing temperature, the center of the peak position Δλ¯c shifts toward higher amplitudes while their broadness also increases (Fig. 4A). On the one hand, this result is in line with our previous finding from the comparison of KF and Taq polymerase (Fig. 3) that the more active polymerase induces higher spike amplitudes (Fig. 4B). On the other hand, it further supports the premise that the recognized signals are not influenced by the ptDNA strands in terms of the direct addition of molecular mass to the Pfu molecules through binding. Furthermore, the fact that the peak center consistently shifts toward higher amplitudes as the temperature is adjusted toward values that favor the polymerase’s activity strongly suggests a relation between the spike amplitudes and conformational changes associated with the ptDNA/Pol interactions. These results specifically indicate that upon the incorporation of ptDNA, the ptDNA/Pfu complex additionally undergoes a conformational change in such a manner that its time-averaged field overlap integral Ī increases as compared to the moment of the initial ptDNA/Pfu interaction. Toward higher temperatures (where the enzyme has higher activity), this conformational transition that the ptDNA/Pfu complex undergoes evolves in such a way that the ΔI¯ increases, which can be interpreted as an increase in the (time-averaged) magnitude of the conformational change.
Fig. 4 sm-DNA/Pol interaction signals using the immo-Pol scheme.
(A) Average spike amplitude Δλ¯ distributions obtained for Pfu/ptDNA/dNTP interactions showing the evolution of overall signal amplitude with increasing temperature and enzyme activity. Peak center positions Δλ¯c extracted via lognormal fits (solid lines) are indicated by dashed lines. (B) Δλ¯c for different DNA polymerase species (Taq, KF, and Pfu) and temperatures. (C) Distributions of spike durations Δτ obtained for Pfu/ptDNA/dNTP interactions at two different temperatures. The concentrations of ptDNA and dNTPs in the solution were kept to 1 and 50 μM, respectively.
Furthermore, the spike durations observed for the Pfu/ptDNA/dNTP interactions also become shorter as the temperature and, thus, the expected activity of the polymerase increase (Fig. 4C). This is in line with the expectation that the polymerase processes the ptDNA faster and consequently releases it earlier under more favorable ambient conditions.
We next compare the temperature-dependent Pfu/DNA interactions in the absence and presence of dNTPs (see Fig. 5). Independent of the presence of dNTPs, the peak centers of the spike amplitude distributions shift again toward higher amplitudes with increasing temperature, whereas the shifts are larger if dNTPs are present (Fig. 5A). Furthermore, we find that Δλ¯c∝eAT (Fig. 4B), where the values for A as determined from the corresponding Arrhenius plots (Fig. 5B) yield −6.5 × 103 ± 0.9 × 103 K (−1.7 × 103 ± 0.7 × 103 K) in the presence (absence) of dNTPs. The precise numerical values for Δλ¯c are listed in table S1. Here, the overall higher spike amplitudes that were found in the presence of dNTPs might be associated with the polymerase undergoing changes between additional conformational substates accompanying the extension of the primer strand by possibly multiple dNTPs (the sensor’s time resolution is too low to resolve the incorporation of single dNTPs), yielding an increased ΔI¯. The temperature dependence of the koff values as extracted from spike duration (Δτ) distributions, however, displays a significant difference with respect to the presence of dNTPs. Although we find that koff∝eBT for both cases, the sign of the values for B as extracted from the corresponding Arrhenius plots (Fig. 5D) is different and B values yield −3.8 × 103 ± 0.6 × 103 K (2 × 103 ± 1 × 103 K) in the presence (absence) of dNTPs. The result obtained in the presence of dNTPs is in line with what we had found before, namely, the increasing speed of the enzymatic process. However, in the absence of dNTPs, the spike durations increase with increasing temperature (Fig. 5C). This indicates that after the ptDNA/Pfu complex is formed, it remains in a certain conformation for a duration that increases as the temperature increases, until the ptDNA is eventually released again. This, in turn, implies that the ptDNA/Pfu complex is more stable at higher temperatures. From an enzymatic point of view, such a property is certainly desirable because, in this state, the polymerase is waiting for the arrival of dNTPs and a premature release of the ptDNA would be a waste of energy. These results, especially the distinctively different temporal behavior in the presence and absence of dNTPs, provide strong evidence that the monitored conformational changes accompanied by the Pfu/DNA complex formation involved the incorporation of nucleotides.
Fig. 5 Different conformational transitions in the presence and absence of dNTPs.
(A) Comparison between average spike amplitude Δλ¯ distributions obtained for Pfu/DNA interactions in the absence (top) and presence (bottom) of dNTPs (50 μM) at 296 and 315 K. Arrhenius plots displaying the temperature dependence of (B) Δλ¯c and off-rates koff (D) found for Pfu in the presence and absence of dNTPs. (C) Change of the spike duration distributions at two different temperatures in the absence of dNTPs. (A) and (C) were obtained with the same Pfu/NR-modified microsphere, whereas (B) and (D) show data obtained with six different sensors.
CONCLUSIONS
We have demonstrated our sensor’s capability to detect polymerase/DNA interactions linked to enzymatic activity on a single-molecule level by monitoring the kinetics and conformational transitions of DNA polymerases. Our results exhibit a clear correlation between our sensor’s signal and the enzymatic activity of three different types of polymerases at various ambient temperatures. Moreover, we have shown that the magnitude and duration of the conformational changes of the polymerase associated with DNA interactions vary with respect to the presence and absence of dNTPs. In this context, we have found a distinct difference in the temperature dependence of the enzymes’ kinetic behavior, providing strong evidence for the correlation of our sensor’s signal with enzymatic activity in the form of nucleotide incorporation.
Our results are potentially significant because monitoring enzymatic activity in a multiplexed and high-throughput fashion is a crucial requirement for next-generation sequencing. The fact that our approach is label-free and the sensor’s signals can be monitored in real time opens a new and direct way to determine conformational substates of various proteins without the necessity to mitigate label-associated background fluctuations. However, our sensor is intrinsically limited by our signal amplification method because the plasmonically enhanced near field may only probe a fraction of the enzyme’s volume. This limitation might become an advantage because it may, in turn, allow for the selective probing of certain protein subdomains. Furthermore, enzymatic kinetics can be easily tested with respect to diverse medium conditions, such as molecule concentrations, ionic strength, pH, and temperature. In this context, combining our method with label-based techniques would be promising when linked to the extensive knowledge already established via label-based methods, thus diversifying quantitative analysis. For example, in combination with FRET, our sensor would allow for probing of conformational changes beyond FRET’s spatial limitations yet take advantage of its selectivity. Moreover, the temperature dependence of polymerase/DNA interactions can be further investigated by optically driven local heating of the NRs, which may allow for fast switching of the enzymes’ activity and the corresponding interaction kinetics.
METHODS
All solutions without NRs were filtered with 0.1-μm syringe filters (Merck Millipore) before usage. The power that was coupled to microspheres was <0.1 mW overall, accounting for an average total energy of <20 nJ being coupled to the resonators per wavelength sweep.
The immo-DNA recognition scheme
Sensor assembly was conducted by adopting a modified version of the three-step wet-chemical procedure used in the study by Baaske et al. (13). First, cetyltrimethylammonium bromide–stabilized gold NRs with diameters of 10 nm and lengths of 35 nm (Nanopartz) were immobilized on the microresonator surface. For this, the NRs were injected into a sample cell holding about 0.5 ml of 100 mM NaCl solution at pH ≈ 1.6. This process was directly monitored, and individual NR binding events were classified as discrete steps in the resonance position and linewidth traces. Second, thiol-modified ssDNA ([ThiC6]-5′-TTTTCTCGTTGGGGTCTTTGCTC, Eurofins) were conjugated to the adsorbed NRs. To cleave any disulfide bonds, we treated the thiolated DNA with 100 mM dithiothreitol and 100 mM NaCl for 30 min at room temperature before measurement (22). The NR-modified sphere was then immersed in a solution with 500 mM NaCl, 0.02% (w/w) SDS at pH ≈ 3, and 1 μM DNA (13, 23). The time spans required to produce a surface coverage that was sufficient to monitor sm-DNA/Pol interactions were in the range of 10 to 30 min, although longer reaction times may result in undesirably high DNA surface densities and hinder protein-DNA interactions. Last, in NEBuffer 2 (New England BioLabs Inc.), the initial pH of the solution was reduced to 6.7 by adding 2 mM HCl to maintain stable NR adsorption. If required, ssDNA was hybridized to ptDNA by injection of the template strand DNA (60 nt, CCGACAACCACTACACCGGTCTGAGCACCCAGTCCGCCCTGAGCAAAGACCCCAACGAGA), followed by the introduction of the desired amount of polymerase (that is, Taq and KF; New England BioLabs Inc.).
The immo-Pol recognition scheme
Sensor assembly was performed according to the following steps. First, polymerase-gold NR conjugates were prepared by mixing 2 μl of Pfu DNA polymerase (BioVision) from a stock solution (2.5 U/μl) with 5 μl of a solution containing citrate gold NRs (diameter, 25 nm; length, 49 nm; Nanopartz) at a concentration of 5.7 × 1011 nanoparticles/μl. Second, the surface of the freshly fabricated microsphere was functionalized with aminopropyltriethoxysilane (C9H23NO3Si; APTES) by immersing the microsphere in a 100-μl droplet of 2.5% (v/v) APTES for about 1 to 2 min. The binding of Pfu-NR conjugates to the microsphere was then performed in a sample chamber filled with PCR buffer. The PCR buffer contained 10 mM tris-HCl, 50 mM KCl, 1.5 mM MgCl2, and 0.001% (w/v) gelatin (Sigma-Aldrich). Last, the ptDNA used for the measurements was prepared by mixing the template and primer strands (1:1 molar ratio) in a solution containing 50 mM NaCl. This mixture was heated to 94°C in an Eppendorf incubator and cooled down to room temperature before use. The observation of ptDNA and immobilized Pfu polymerase was then undertaken in the PCR buffer.
Numerical analysis
Numerical simulations were performed using COMSOL Multiphysics (frequency-domain module). The polymerase was modeled as three rectangular parallelepipeds (6 nm × 4 nm × 5 nm for the moving arms and 2 nm × 5 nm × 5 nm for the stationary bottom) that are conjugated with two cylinders (2 nm × 5 nm) to maintain a constant volume while increasing the angle between the two arms. It was initially attached to the center of the gold NR’s tip, and this gold NR was modeled as a prolate circular cylinder with hemispherical end caps with dimensions of 25 nm × 49 nm. The refractive index of the surrounding medium (water) used for the simulation was 1.332, and the frequency-dependent refractive index values of gold were taken from the study by Johnson and Christy (24). The simulation domain was surrounded by a perfectly matched layer (PML) to absorb the outward-propagating radiation. To calculate the local field enhancement, we illuminated the entire domain with a plane wave at a pump wavelength of 642 nm. The polarization state of the incoming field was parallel to the long axis of the NR. With regard to meshing, a swept mesh was used to discretize the external and PML domain. Note that the NR and polymerase domains were meshed using free tetrahedral discretization, whereas the finer meshes were used in the NR and polymerase domains.
Supplementary Material
http://advances.sciencemag.org/cgi/content/full/3/3/e1603044/DC1
Acknowledgments
We thank C. Koch from the Biochemistry chair of Friedrich-Alexander University Erlangen-Nürnberg for providing access to the PCR instrument. E.K. and M.D.B. thank S. Vincent for his feedback on the manuscript. Funding: We acknowledge financial support from the Max Planck Society. Author contributions: E.K. and M.D.B. wrote the manuscript and performed the simulation and developed the experimental setup. M.D.B. developed data analysis tools and supervised the experiment. P.S.W., I.S., and E.K. performed the experiment. F.V. supervised the entire project. All authors commented on the manuscript. Competing interests: The authors declare that they have no competing interests. Data and materials availability: All data needed to evaluate the conclusions in the paper are present in the paper and/or the Supplementary Materials. Additional data related to this paper may be requested from the authors.
SUPPLEMENTARY MATERIALS
Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/3/3/e1603044/DC1
section S1. Real-time monitoring of the NR immobilization procedure
section S2. Single-molecule analysis
section S3. Control experiments
section S4. PCR experiments
section S5. KF interactions with ssDNA and ptDNA/dNTP
section S6. Signal comparisons between Pfu-immobilized NRS and bare NRS interacting with a WGM cavity
section S7. Pfu polymerase interactions with two different lengths of ptDNA
section S8. Additional information
section S9. Discussion on the detection of freely diffusing polymerase molecules
fig. S1. Time-traced WGM resonance positions (Δ) and linewidth broadening (ΔΓ) with step-like changes induced by binding of individual NRs (dimensions, 25 nm × 49 nm; λlaser = 642 nm).
fig. S2. Single-molecule statistics.
fig. S3. Control experiments.
fig. S4. Gel of the PCR with citrate NRs and Taq/Pfu polymerase.
fig. S5. Comparison of KF interactions associated with ssDNA and ptDNA/dNTP.
fig. S6. Comparison of transient changes in WGM response position and WGM linewidth as induced by NRs (before and after Pfu-surface functionalization) entering the WGM’s evanescent field.
fig. S7. Pfu-polymerase interactions with two different lengths of ptDNA strands.
fig. S8. Sketch of the model used to perform Monte Carlo simulations.
fig. S9. Probabilities of a polymerase molecule to be still located inside the detection volume after a certain duration of time as obtained from Monte Carlo simulations using different initial molecule positions.
fig. S10. Probabilities of detecting resonance shifts with amplitudes of 15 (black) and 30 (red) fm of perturbations with a certain duration as shifts above 3σ (solid lines) or σ (dashed lines) during one wavelength sweep of the laser (20 ms).
fig. S11. Zoom in showing probabilities Pdet and Ploc plotted on the interval and for the cases where they overlap with nonzero values.
fig. S12. Zoom in showing Pres.
table S1. Numerical values used in the fitting process of PPoisson to Pmeas in fig. S2, alongside the respective coefficients of determination R2.
table S2. Numerical values of the results shown in the Arrhenius plots of Fig. 5.
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Medicine (Baltimore)Medicine (Baltimore)MEDIMedicine0025-79741536-5964Wolters Kluwer Health 28328798MD-D-15-0581510.1097/MD.0000000000005290052906600Research ArticleSystematic Review and Meta-AnalysisBody mass index and the risk of low bone mass–related fractures in women compared with men A PRISMA-compliant meta-analysis of prospective cohort studiesXiang Bing-Yan PhDaHuang Wei PhDa∗Zhou Guo-Qi PhDbHu Ning PhDaChen Hong PhDaChen Cheng MDaIriti. Marcello a Department of Orthopaedic Surgery, The First Affiliated Hospital of Chongqing Medical University, Chongqingb Department of Respiratory Medicine, Three Affiliated Hospital of Zunyi Medical College, Guizhou, China.∗ Correspondence: Wei Huang, Department of Orthopaedic Surgery, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, China (e-mail: huangweichongqing@163.com).3 2017 24 3 2017 96 12 e529023 12 2015 5 7 2016 30 9 2016 Copyright © 2017 the Author(s). Published by Wolters Kluwer Health, Inc.2017This is an open access article distributed under the terms of the Creative Commons Attribution-Non Commercial-No Derivatives License 4.0 (CCBY-NC-ND), where it is permissible to download and share the work provided it is properly cited. The work cannot be changed in any way or used commercially without permission from the journal. http://creativecommons.org/licenses/by-nc-nd/4.0Abstract
Background:
Body mass index (BMI) is inconsistently associated with the progression of low bone mass–related fractures. We conducted a systematic review and meta-analysis to summarize the evidence regarding the relationship between BMI and the risk of fracture in men and women separately. Furthermore, we analyzed the association between BMI and fracture risk in women compared with men.
Methods:
PubMed, EmBase, and the Cochrane Library were searched up to November 2015 to identify prospective cohort studies of low bone mass–related fractures. Prospective cohort studies that reported effect estimates of fracture risk for different BMI categories compared to normal weight were included. Relative risk (RR) and the ratio of relative risk (RRR) were calculated using a random-effect model to measure the relationship between BMI and fracture risk.
Results:
We analyzed 37 cohorts (32 articles), which included a total of 506,004 women and 118,372 men; overall, 38,200 incident cases were reported. Overall, a lower BMI was not associated with fracture risk in men (RR: 1.50, 95% confidence interval [CI]: 1.00–2.26; P = 0.051) or women (RR: 1.25, 95% CI: 0.97–1.62; P = 0.083). Although a higher BMI might play a beneficial impact in men (RR: 0.80, 95% CI: 0.69–0.93; P = 0.003), it has little effect in women (RR: 0.91, 95% CI: 0.74–1.11; P = 0.343). In addition, an increase in BMI by 5 kg/m2 decreased the risk of fractures in men (RR: 0.90, 95% CI: 0.83–0.98; P = 0.017) and women (RR: 0.85, 95% CI: 0.81–0.89; P < 0.001). Finally, there was no evidence of a sex difference in the RR for fractures between participants with different BMI categories compared with those with normal BMI. Finally, gender did not affect the risk of fracture for any category of BMI values.
Conclusion:
Higher BMI may affect the risk of fractures regardless of the sex. This association may be due to the interaction between the participants’ BMI and their bone mass density.
Keywords
body mass indexfracturegendermeta-analysisOPEN-ACCESSTRUE
==== Body
1 Introduction
The World Health Organization defines obesity as a body mass index (BMI) ≥30 kg/m2, overweight as a BMI = 25 to 29.9 kg/m2, and underweight as a BMI < 18.5 kg/m2.[1] Guh et al[2] identified a number of comorbidities relating to obesity including osteoarthritis, diabetes, coronary heart disease, and some forms of cancer. The prevalence of overweight and obesity is increasing in the United States.[3] Similarly, the majority of elderly people in European countries and Australia are overweight or obese.[4,5] Although the prevalence of obesity in Asian populations is lower, it is increasing rapidly.[6]
Low BMI increases fracture risk, possibly because low BMI is associated with low bone mineral density (BMD), less soft tissue, and muscle weakness[7]; however, the relationship between high BMI and fracture risk is complex. Therefore, interest in studying the influence of obesity and overweight on the risk of fracture has recently increased. As an independent risk factor, obesity may increase the risk of all osteoporotic and hip fractures.[8,9]
According to a previous meta-analysis,[10] higher BMIs lower the fracture risk in women but not in men. This suggests that BMI affects fracture risk differently in men and women; however, the study was limited by a small sample size. Furthermore, a case–control study suggested that BMI had no effect on hip fracture risk due to a linear associations between body size and adiposity variables.[11] Nevertheless, another meta-analysis evaluated an important nonlinear relationship between BMI and the risk of fracture[9]; however, the meta-analyses[9,10] did not assess and explore the association between BMI and the risk of fracture among the genders in detail. The sex-specific differences in fracture risk associated with BMI are uncertain and need to be evaluated.
As the sex-specific effect of BMI on the rapidly increasing prevalence of obesity[12–14] is unclear,[7] we aim to investigate the association between BMI and fracture risk in men and women separately.
2 Methods
2.1 Data sources, search strategy, and selection criteria
PubMed, EMBASE, and the Cochrane Library databases were searched for articles published since the beginning of studying the relationships between BMI and fractures up to November 2015. The following keywords were used: [“obesity” OR “weight” OR “body weight” OR “body mass” OR “body mass index” OR “anthropometric” OR “anthropometry”] AND [“low bone mass-related fractures” OR “low bone mass” OR “bone fracture” OR “skeletal fracture” OR “osteoporotic fractures” OR “osteoporotic” OR “Osteoporosis” OR “broken bone” OR “low bone density-related fractures”] AND “men” AND “women” AND (“cohort” OR “cohort studies”). The search was limited to articles published in English. Abstracts and virtual meeting presentations from the EMBASE were searched to identify relevant, unpublished clinical trials. We also conducted manual searches of reference lists from all the relevant original and review articles to identify additional eligible studies. The medical subject heading, methods, participant population, design, exposure, and outcome variables of these articles were used to identify the relevant studies. The literature retrieval was performed in duplicate by 2 independent reviewers. This review was conducted and reported according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis Statement issued in 2009 (Checklist S1).[15] Ethics approval was not necessary for this study, as only deidentified pooled data from individual studies were analyzed.
Two authors conducted independent literature searches using a standardized approach, and any inconsistencies were settled by group consensus. Studies were deemed eligible for inclusion if they met the following criteria: they used a prospective cohort design; they evaluated the relationships between BMI and low bone-related fracture risk neglected of sites; they provided the relative risk (RR), hazard ratio (HR), or odds ratio (OR), and their 95% confidence intervals (CIs), of different BMI categories compared with the normal weight category, or per 5 kg/m2 increment of BMI. For studies without adequate data, we contacted the authors or abstracted data from other relevant articles; if the author or the relevant articles could not provide the necessary data, the study was excluded. In addition, case–control studies or retrospective cohort studies were excluded because various confounding factors could bias the results.
2.2 Data collection and quality assessment
Two authors independently conducted data extraction and assessment. Publication information (B-YX), characteristics of participants (country, gender, assessment of exposure, sample size, age at baseline, and duration of follow-up), and outcomes (fracture incident and effect estimate for the relationship between BMI and fracture) were extracted. Disagreement was resolved by consensus with a third reviewer. Two reviewers independently evaluated the quality of the studies using the Newcastle–Ottawa Scale (NOS).[16] The NOS assesses the selection (4 items), comparability (1 item), and outcome (3 items) of observational studies. The NOS is an 8-point questionnaire that produces a total score ranging from 0 (the worst) to 9 (the best). Disagreements between reviewers were resolved by consensus.
2.3 Statistical analysis
We examined the relationship between BMI and fracture risk by reviewing the effect estimate (RR, HR, or OR) and its 95% CI for each study. We used a random-effects model to calculate summary RRs and 95% CIs for the underweight (<18.5 kg/m2) category and overweight (>25.0 kg/m2) category compared to the normal weight (18.5–24.9 kg/m2) category.[17,18] Furthermore, we combined the RRs for each 5 kg/m2 increase in BMI by using a random-effect meta-analysis.[17,18] Finally, a random-effect model was used to evaluate the ratio of relative risk (RRR) of different BMI categories (compared to the normal weight category) in women compared with men.[17–19] Heterogeneity between studies was investigated by using the Q statistic, and we considered P values <0.10 to be indicative of significant heterogeneity.[20] Subgroup analyses were conducted of adjusted and raw BMD values. We performed a sensitivity analysis by removing each individual study from the meta-analysis.[21] The Egger and Davey Smith[22] and Begg and Mazumdar tests[23] were used to statistically assess publication bias. All reported P values are 2-sided, and P values <0.05 were considered statistically significant. Statistical analyses were performed using STATA software (version 12.0; Stata Corporation; College Station, TX).
3 Results
3.1 Literature search and study characteristics
The primary search produced 2842 records. After scanning titles and abstracts, we excluded 2763 irrelevant articles. The remaining 79 full-text articles were reviewed, and 37 prospective cohorts (32 articles)[10,24–54] were selected for this meta-analysis, with a total of 506,004 women and 118,372 men (Fig. 1). A manual search of the studies’ reference lists did not yield any new eligible studies. The general characteristics of the included studies are presented in Table 1. The follow-up period for participants in the included studies ranged from 2.8 to 30.0 years, and the number of participants in each study ranged from 400 to 180,093. Study quality was assessed using the NOS scale (Table 1), and we considered a high-quality study to have an NOS score ≥7. Overall, 2 cohorts[26,46] had a score of 9, 8 cohorts[25,32,41,44,45,51,53] had a score of 8, 18 cohorts had a score of 7,[10,24,27,30,33,34,37–39,42,43,47,49,50,54] 7 cohorts[28,29,36,40,48,52] had a score of 6, and the remaining 2 cohorts[31,35] had a score of 5.
Figure 1 Flow diagram of the literature search and trials selection process.
Table 1 Baseline characteristic of studies included in the systematic review and meta-analysis.
3.2 Underweight versus normal weight
The summary RR showed that being underweight was not associated with fracture risk in men (RR: 1.50, 95% CI: 1.00–2.26; P = 0.051) or women (RR: 1.25, 95% CI: 0.97–1.62; P = 0.083), and evidence of significant heterogeneity was seen (Table 2). Furthermore, the RRR (female-to-male) was reduced by 17% (RRR: 0.83, 95% CI: 0.51–1.35; P = 0.458) for underweight participants compared to normal-weight participants, but this reduction was not statistically significant. Finally, the subgroup analysis showed that being underweight had no significant effect on the risk of fractures in men (RR: 0.89, 95% CI: 0.53–1.49; P = 0.658) and women (RR: 0.98, 95% CI: 0.79–1.20; P = 0.816) in BMD-adjusted studies. However, when results were not adjusted for BMD, being underweight increased the risk of fracture in men (RR: 1.89, 95% CI: 1.18–3.15; P = 0.009) and women (RR: 1.51, 95% CI: 1.35–1.68; P < 0.001). Furthermore, although the RRR (female-to-male) increased or decreased, there was no statistical significance for sex-difference in studies adjusted for BMD (RRR: 1.10, 95% CI: 0.63–1.92; P = 0.735) or not (RRR: 0.80; 95% CI: 0.49–1.30; P = 0.367).
Table 2 Summarized results of meta-analyses of relationships between BMI and the risk of fractures.
3.3 Overweight versus normal weight
The pooled analysis results suggested that overweight is associated with lower fracture risk in men (RR: 0.80, 95% CI: 0.69–0.93; P = 0.003), whereas overweight has no significant impact on fracture risk in women (RR: 0.91, 95% CI: 0.74–1.11; P = 0.343). There was no evidence of heterogeneity for men but substantial heterogeneity for women (Table 2). Furthermore, the RRR (female-to-male) increased by 14% for overweight participants compared to normal-weight participants (RRR: 1.14, 95% CI: 0.88–1.46; P = 0.316); however, this increment was not statistically significant.
The subgroups of adjusted BMD values and raw BMD values were analyzed. The summary RR for BMD-adjusted studies suggested that being overweight had no effect on fracture risk in men (RR: 0.74, 95% CI: 0.42–1.30; P = 0.297) or women (RR: 1.05, 95% CI: 0.84–1.30; P = 0.685). Although the RRR (female-to-male) increased by 42% for BMD-adjusted studies, there was no significant gender difference (RRR: 1.42, 95% CI: 0.77–2.60; P = 0.258). In addition, the pooled RR, unadjusted for BMD, indicated that overweight was associated with lower risk of fractures in men (RR: 0.81, 95% CI: 0.69–0.94; P = 0.005) and women (RR: 0.83, 95% CI: 0.74–0.94; P = 0.003). There was no significant difference in the effect of being overweight on the fracture risk between women and men (RRR: 1.02, 95% CI: 0.84–1.25; P = 0.807).
3.4 Per 5 kg/m2 increment in BMI
Data showing the effect of a 5 kg/m2 increment in BMI on the risk of fractures were reported in 3 studies for men and 2 studies for women. All of these studies did not adjust BMD, and the pooled results indicated that increasing BMI in 5 kg/m2 increments decreased fracture risk for men (RR: 0.90, 95% CI: 0.83–0.98; P = 0.017) and women (RR: 0.85, 95% CI: 0.81–0.89; P < 0.001). Furthermore, the RRR (female-to-male) was 0.94, but this reduction was not statistically significant (RRR: 0.94, 95% CI: 0.86–1.04; P = 0.241; Table 2).
3.5 Publication bias
The Egger and Davey Smith[22] and Begg and Mazumdar[23] test results showed no evidence of publication bias for men (underweight vs normal weight [Egger: 0.732, Begg: 0.462] and overweight vs normal weight [Egger: 0.503, Begg: 0.452]) and women (underweight vs normal weight [Egger: 0.112, Begg: 0.462]). Although the Begg test showed no evidence of publication bias for women (overweight vs normal weight [P = 0.806]), the Egger test showed potential evidence of publication bias (P = 0.081). Adjustment for publication bias, performed using the trim and fill method, did not change our conclusions.[55]
4 Discussion
This analysis of prospective studies explored the effect of BMI values on the risk of low bone mass–related fractures. This large quantitative study included 506,004 women and 118,372 men from 37 prospective cohorts with a broad range of study populations. The findings from our meta-analysis suggest that being underweight has no effect on the incidence of fractures in men and women. However, being underweight significantly increased fracture risk in men and women when results were unadjusted for BMD. Furthermore, being overweight decreased fracture risk in men but did not affect fracture risk in women. In addition, the findings of the pooled analysis indicated that as BMI increased by 5 kg/m2, the risk of fracture decreased in men and in women. Finally, the RRR (female-to-male) indicated that there was no significant association between BMI and fracture risk.
A previous meta-analysis[38] of women suggested that being underweight increases the risk of hip and osteoporotic fractures, but may decrease the risk of leg fracture. Furthermore, being overweight may increase the risk of upper arm fracture. The relationship between BMI and low bone mass–related fractures in women might vary after BMD adjustment. Another important meta-analysis[56] of observational studies suggested that lower BMI is associated with higher risk of fractures in men (RR: 1.12, 95% CI: 1.04–1.20). Furthermore, fracture risk increased with every 5 kg/m2 decrease in BMI (RR: 1.30, 95% CI: 1.15–1.47). However, there are some possible limitations of these meta-analyses. First, the studies only evaluated either men or women; consequently, the gender difference was not established. Furthermore, retrospective observational studies were included, which might bias the results. Finally, the interaction between BMI and BMD may modify the relationship between BMI and fracture risk. Therefore, we performed a comprehensive meta-analysis of prospective cohort studies to evaluate any potential correlation between BMI and fractures and included an assessment of the related gender differences.
Most of our findings were in agreement with a previous cohort study conducted in California[49] that included 8600 women and 5049 men. The study found that a high BMI was associated with a strong reduction in hip fracture risk for women, whereas has slight impact for men. Meyer et al[48] suggested that a high BMI is not associated with fracture risk in women, but is strongly associated with a reduced risk of fracture in men. Søgaard et al[51] indicated that being underweight increases the risk of fractures for both men and women. They found that women with a higher BMI had a lower risk of fracture, whereas have a slight impact in men. Our meta-analysis suggests that a low BMI has no effect on fracture risk, whereas overweight men may have a lower risk of fracture. The possible reason for this could be that participants with different BMI levels might play an important role on BMD, which are important interaction confounders for the relationship between BMI and fractures. Furthermore, the waist/hip ratio may be affected by the BMI and also impacts the risk of fracture. Finally, participants with a low BMI are usually tall and underweight. When tall people fall over, they fall from a greater height; consequently, their velocity at impact with the surface may be greater. Moreover, individuals with a different padding effect of the soft tissues may produce diverse energy dissipation after trauma.[57]
There was no significant difference between participants who were underweight and of a normal weight on the risk of low bone mass–related fractures for men and women. However, several studies, including our own, reported inconsistent results. The Leisure World Study[49] suggested that being underweight increases the risk of fracture by 79% in women. Furthermore, the study conducted by Søgaard et al[51] reported similar results in women and men. Finally, Meyer et al[48] suggested that participants with a lower BMI have an increased risk of fracture. The possible reasons for these could be that these studies with longer duration of follow-up periods, and event rates were greater than expected, which always acquired narrow CIs, that is, with statistical significance. In addition, the pooled effect estimate, of nearly 0.05, suggests that being underweight could affect the fracture risk. The reason this association was not significant was perhaps that most trials in our study were designed with other indexes, not for fracture as a primary end point, and their sample sizes were too small to detect potential relationships.
In our study, lower BMI values were associated with a higher fracture risk, and higher BMI values were associated with a lower fracture risk when the results were not adjusted for BMD. These findings were inconsistent with BMD-adjusted studies. This could be because BMD may affect the relationship between BMI and fractures in men and women. Another study concluded that lower BMIs are an important risk factor for low bone mass and increased bone loss in postmenopausal women. The study found that low bone mass and an increased rate of bone loss were associated with an increased risk of postmenopausal osteoporosis.[58] However, as our study included smaller patient cohorts, we are unable to draw such conclusions. Therefore, we gave a relative result and provided a synthetic and comprehensive review.
Three strengths of our study should be highlighted. First, as only prospective studies were included, this should eliminate selection and recall bias, which are possible concerns in retrospective case–control studies. Second, the large sample size allowed us to quantitatively assess the association of BMI with the risk of low bone mass–related fractures, and thus our findings are potentially more robust than the findings of any individual study. Finally, gender difference analyses were conducted to evaluate the relationship between BMI and fracture risk.
Our study had several limitations. First, as the results of the majority of the included studies were only adjusted for age and were not adjusted for any other potential confounders, the fracture risk may have been affected. Second, stratified effect estimates on the basis of mean age, the duration of the follow-up periods, and sites of fracture were not available in individual study, so we could not perform the association between BMI and fractures in specific subsets, and not differentiate this relationship by sites of fracture. Third, in a meta-analysis of published studies, publication bias is an inevitable problem. Finally, our analysis used pooled data (as individual data were not available), which restricted us from performing a more detailed, relevant analysis to obtain results that were more comprehensive.
The results of this study suggest that higher BMI values affect the risk of fracture, but lower BMI values do not affect the risk of fracture. According to our sex difference analysis, there was no evidence of a sex difference in the RR for fractures among underweight or overweight participants.
Abbreviations: BMD = bone mineral density, BMI = body mass index, CI = confidence interval, HR = hazard ratio, NOS = Newcastle–Ottawa Scale, OR = odds ratio, RR = relative risk, RRR = ratio of relative risk.
Funding/support: The study was conducted under a grant from Special Fund for Scientific and Technological Cooperation of Zunyi, Guizhou (2015-41). The funders had no role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript.
The authors have no conflicts of interest to disclose.
==== Refs
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Medicine (Baltimore)Medicine (Baltimore)MEDIMedicine0025-79741536-5964Wolters Kluwer Health 28328799MD-D-16-0354010.1097/MD.0000000000005821058214850Research ArticleObservational StudyOral microbiome in HIV-associated periodontitis Noguera-Julian Marc PhDabc∗Guillén Yolanda PhDabPeterson Jessica BsCdReznik David DDSdeHarris Erica V. BsCfJoseph Sandeep J. PhDdRivera Javier MsCacKannanganat Sunil PhDdgAmara Rama PhDdgNguyen Minh Ly MDdMutembo Simon MDhParedes Roger MD, PhDabciRead Timothy D. PhDdMarconi Vincent C. MDdg∗Leeansyah. Edwin a IrsiCaixa AIDS Research Institute, Badalonab University Autònoma de Barcelona, Bellaterrac University de Vic-University Central de Catalunya, Vic, Catalonia, Spaind Division of Infectious Diseases, Emory University School of Medicinee Infectious Diseases Program, Grady Health Systemf Department of Biology, Emory University, O. Wayne Rollins Research Centerg Department of Global Health, Emory University Rollins School of Public Health, Atlanta, GAh Ministry of Health, Zambiai Unitat VIH, Hosp. University Germans Trias i Pujol, Badalona, Catalonia, Spain.∗ Correspondence: Marc Noguera-Julian, Institut de Recerca de la SIDA IrsiCaixa-HIVACAT, Hospital Universitari Germans Trias i Pujol. Ctra de Canyet s/n., Badalona, Catalonia, Spain (e-mail: mnoguera@irsicaixa.es); Vincent C. Marconi, Division of Infectious Diseases, Emory University School of Medicine, Atlanta, GA (e-mail: vcmarco@emory.edu).3 2017 24 3 2017 96 12 e582119 5 2016 12 12 2016 13 12 2016 Copyright © 2017 the Author(s). Published by Wolters Kluwer Health, Inc.2017This is an open access article distributed under the terms of the Creative Commons Attribution-Non Commercial License 4.0 (CCBY-NC), where it is permissible to download, share, remix, transform, and buildup the work provided it is properly cited. The work cannot be used commercially without permission from the journal. http://creativecommons.org/licenses/by-nc/4.0Supplemental Digital Content is available in the text
Abstract
HIV-associated periodontal diseases (PD) could serve as a source of chronic inflammation. Here, we sought to characterize the oral microbial signatures of HIV+ and HIV– individuals at different levels of PD severity.
This cross-sectional study included both HIV+ and HIV– patients with varying degrees of PD. Two tooth, 2 cheek, and 1 saliva samples were obtained for microbiome analysis. Mothur/SILVADB were used to classify sequences. R/Bioconductor (Vegan, PhyloSeq, and DESeq2) was employed to assess overall microbiome structure differences and differential abundance of bacterial genera between groups. Polychromatic flow cytometry was used to assess immune activation in CD4 and CD8 cell populations.
Around 250 cheek, tooth, and saliva samples from 50 participants (40 HIV+ and 10 HIV–) were included. Severity of PD was classified clinically as None/Mild (N), Moderate (M), and Severe (S) with 18 (36%), 16 (32%), and 16 (32%) participants in each category, respectively. Globally, ordination analysis demonstrated clustering by anatomic site (R2 = 0.25, P < 0.001). HIV status and PD severity showed a statistically significant impact on microbiome composition but only accounted for a combined 2% of variation. HIV+ samples were enriched in genera Abiotrophia, Neisseria, Kingella, and unclassified Neisseriaceae and depleted in Leptotrichia and Selenomonas. The Neisseria genus was consistently enriched in HIV+ participants regardless of sampling site and PD level. Immune markers were altered in HIV+ participants but did not show association with the oral microbiome.
HIV-associated changes in oral microbiome result in subtle microbial signatures along different stages of PD that are common in independent oral anatomic sites.
Keywords
HIVNeisseriaoral microbiomeperiodontal diseaseOPEN-ACCESSTRUE
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1 Introduction
Periodontal disease (PD) includes a number of inflammatory-based conditions such as gingivitis and periodontitis, which are the most common infectious diseases affecting tooth-supporting bone structures. Untreated periodontitis affects more than 700 million people worldwide,[1] can lead to tooth loss, and has been linked to conditions such as cardiovascular disease, diabetes mellitus, or obesity.[1]
Over the last 30 years, severe PD has been associated with HIV infection.[2] Although antiretroviral therapy (ART) preserves and restores immune function and prevents the development of opportunistic infections, individuals with sustained virological suppression continue to experience an increased incidence of age-related comorbidities (including PD) with synergistic effects on survival and quality of life. The determinants, course, and impact on other comorbid conditions of severe PD in the setting of ART remain a matter of controversy.[3,4]
In classical microbiology descriptions, increases in Porphyormonas gingivalis, Treponema denticola, and Tannerella forsythia, the so-called red complex, were strongly associated with destructive PD, whereas predominance of other bacterial complexes was associated to less severe PD.[5–8] The formation of plaque in mature teeth with an enriched proportion of Gram-negative anaerobic bacteria activates pro-inflammatory pathways and promotes the formation of periodontal pockets. These pockets allow for the local accumulation of anaerobic bacteria, against which the host response is inefficient and even counter-productive. With the arrival of new sequencing technologies, periodontitis has been linked to a broader disbyosis in the oral microbiome, initiated by changes in key pathogenic species with a context of accessory pathogens and their expression profiles. These changes promote a proinflammatory community and can trigger tissue destruction augmented by the host immune response.[9–16]
To date, research on the interplay between HIV infection, the oral microbiome, and PD has produced inconclusive results. A small study in children with only 5 HIV-negative controls found no evident differences in the oral microbiome composition between well-controlled HIV-positive and HIV-negative children.[17] In comparison, 15 subjects with AIDS attending HIV clinics in China showed significant increases in several bacteria, and a distinct salivary bacterial profile between necrotic and chronic PD.[18] Using a microbial microarray, there were significant differences in the salivary bacterial composition between HIV-positive subjects before and after ART initiation and between them and HIV-negative adults.[19] Moreover, an independent study revealed increased diversity in subgingival biofilms of HIV+ individuals within a Brazilian cohort of 32 subjects with PD.[20]
Here, we sought to characterize how HIV infection and other related factors modulate oral microbiome communities in different PD states using high throughput technologies and also identify specific oral microbiome markers of HIV infection.
2 Methods
2.1 Study design
This was a cross-sectional study including both HIV+ and HIV– participants with varying degrees of PD. HIV+ patients were recruited in the Oral Health Center of Infectious Disease Program at Grady Memorial Hospital located in Atlanta, GA. HIV-1 infection was documented by ELISA and confirmed by Western blot at any time prior to study entry. HIV– control samples were obtained from clinical and research staff at the same institution. HIV– participants were required to demonstrate HIV seronegativity in the prior 30 days before inclusion in the study by HIV free testing at the Infectious Disease Program Ponce Clinic.
PD was assessed by the oral exam using the Centers for Disease Control/merican Academy of Periodontology (CDC/AAP) criteria based on the tooth clinical attachment level (CAL) and the probing pocket depth (PPD):[21](1) Severe PD (S-PD): both >2 interproximal sites with CAL >6 mm and >1 interproximal site with PPD >5 mm.
(2) Moderate PD (M-PD): either >2 interproximal sites with CAL >4 mm or >2 interproximal site with PPD >5 mm.
(3) Mild/none PD (N-PD): neither S-PD nor M-PD.
Exclusion criteria included: (A) fewer than 20 teeth in the oral cavity, (b) need for antibiotic prophylaxis for more than 12 hours prior to dental care as per the current American Dental Association guidelines or use of an antibiotic in the 14 days prior to the study visit, (c) use of an antimicrobial mouth rinse (0.12% chlorhexidine gluconate) 30 days prior to the study visit, (d) use of teeth whitening in the 30 days prior to the study visit, and (e) treatment of periodontal disease in the 30 days prior to the study visit. HIV+ patients were stratified by PD severity, whereas HIV– patients were only stratified at the analysis stage due to the limited number of controls available.
2.2 Sample collection
Each participant had data abstracted from the medical record at the time of enrolment which included demographics, date of HIV diagnosis, opportunistic infections, laboratory values including CD4 counts and HIV viral load levels, serologic status, major clinical events including hospitalizations and surgeries, antiretroviral history including adverse events to medications and other co-morbidities, lipids, hemoglobin A1C, HIV-associated conditions (infections, neoplasms, etc), other medical conditions (diabetes, hyperlipidemia), and recent antimicrobial use. In addition, whole blood was obtained from half of the participant for immune activation analysis.
Saliva, cheek mucosa, and teeth specimens were obtained from all participants and stored at –80°C. DNA was extracted within a week and stored at –20°C prior to 16 seconds gene amplification. A curette was used to obtain dental plaque samples from whole teeth, 1 posterior molar, and 1 anterior incisor, in all participants. In participants with PD, samples were taken from the deepest periodontal pocket of teeth that was representative of the participant PD severity. Finally, 2 cheek samples were obtained from each participant. One sample was obtained from the right cheek, and 1 sample was obtained from the left cheek.
Participants were also administered a semistructured questionnaire which assessed demographic data, HIV serostatus, antiretroviral use, oral health behaviors (brushing, flossing), tobacco/illicit drug/alcohol use, diet, use of antimicrobial mouth rinses, dental prosthetic devices or teeth whitening, prior oral/dental history, and utilization of dental care services (number of visits). A dental exam was performed on each participant to assess the missing, decayed, filled (MDF) index, CAL and PPD measurements and to identify other oral cavity conditions or diseases. Finally, a measure of xerostomia was performed involving pH and salivary flow rate measurements.
2.3 DNA extraction, 16 s rRNA gene amplification, and sequencing
Genomic DNA from all samples was extracted utilizing the MoBio PowerSoil DNA Isolation Kit (Cat # 12888–50) and quantified via Quant-iT PicoGreen dsDNA Assay (Cat # P11496). The 16 s V4 region was amplified through 30 cycles PCR with an F515 locus-specific primer (5′-TCGTCGGCAGCGTCAGATGTGTATAAGAGACAG-3′) and an 806R-locus specific primer (5′-GTCTCGTGGGCTCGGAGATGTGTATAAGAGACAG-3′) both with compatible overhang regions for index attachment.[22] PCR cleanup was performed using Agencourt AmpureXP magnetic beads (Cat # A63880). V4 fragments for all samples were indexed utilizing a second PCR reaction with Illumina Nextera Index XT Kit (Cat # FC-121–1012) and index-adhering primers (1.1: 5′-AATGATACGGCGACCACCGAGAT-3′; 2.1: 5′-CAAGCAGAAGACGGCATACGA-3′). Indexed fragments were purified with Ampure XP beads, quantified with dsDNA Picogreen, and pooled with respect to achieving equal molecular concentrations for all samples in the final library. About 250 paired-end sequencing was performed on the MiSeq platform using an Illumina MiSeq Version 2 500-cycle Kit (Cat # MS-102–2003) at a loading concentration of 10 picomolar. An Illumina PhiX control (Cat # FC-110–3001) was utilized in all MiSeq runs as recommended in the MiSeq System User Guide for metagenomic samples.
2.4 Data analysis
Sequence data were quality filtered with trimmomatic.[23] Eight out of 250 (3%) samples (that were represented by less than 1000 sequence counts) were discarded. Mothur phylotype pipeline[24] and SILVADB[25] /GreenGenes[26] databases were used to classify sequences at the genus level. Alpha diversity and richness multiple group comparisons were performed using rank based Mann Whitney or Kruskal–Wallis test combined with post-hoc Nemenyi test implemented in PMCMR R[27] packages. For taxonomical analysis, R/Bioconductor (Vegan,[28] PhyloSeq,[29] and DESeq2)[30] software packages were used. Richness and diversity were estimated using Chao1 and Shannon estimators respectively as implemented in the Vegan package. Principal Coordinates Analysis (PCoA) and weighted Unifrac distances were used for unconstrained ordination on genus proportions. Adonis was used to assess overall microbiome structure differences between defined groups. A negative binomial fit and Wald test were run on every genus to assess differential abundance. P-values were adjusted using the Benjamini–Hochberg correction.[31]
To predict the functional composition of the oral microbiome from 16S data, we used PICRUSt.[32] First, the phylotype table obtained by Mothur/GreenGenesDB was normalized by dividing the abundance of each organism by its predicted 16S copy number (script normalize_by_copy_number.py). To infer the gene content (script predict_metagenomes.py), the normalized phylotype abundances were multiplied by the respective set of gene abundances (represented by KEGG identifiers) estimated for each taxon. The gene content table obtained was used to analyze the metabolic pathways represented at different KEGG level categories structured in 3 hierarchical levels, using HUMAnN.[33] Finally, we identified putative biologically relevant pathways that characterized the different sites, HIV status and PD states by applying the LEfSe algorithm.[34]
2.5 Polychromatic flow cytometry
Flow cytometry and Boolean analysis were performed as previously described[35,36] with a few modifications. Briefly, 2 million peripheral blood mononuclear cells were re-suspended in 100 μL of RPMI plus 10% fetal bovine serum (FBS) in a 5 mL polypropylene tube. Cells were washed once with cold phosphate-buffered saline (PBS) containing 2% FBS, surface stained at room temperature for 30 minutes with antibodies specific to human CD4, CD3, CD8, HLA-DR, and CD38 each conjugated to a different fluorophore. Cells were fixed with cytofix/cytoperm (BD Pharmingen) and permeabilized with 1X permwash (BD Pharmingen). Cells were then incubated with antihuman Ki-67 antibody conjugated to a different fluorochrome for 30 minutes at 4°C. Cells were washed twice with 1 X Permwash, once with 2% Fetal bovine serum(FBS) in phosphate buffered saline (PBS and re-suspended in 1% formalin in PBS. Cells were acquired on the LSRII (BD Immunocytometry systems) and analyzed using the FlowJo software (Treestar, Inc., San Carlos, CA). Lymphocytes were identified based on their scatter pattern, and CD3+, CD8-, CD4+ cells were considered as CD4 T cells, whereas CD3+, CD8+, CD4- cells were considered as CD8 T cells. CD38+, HLA-DR+ or Ki-67+ T cells were further defined on total CD4 or CD8 T cells. Using the CD38, Ki-67 and HLA-DR gates, a Boolean analysis was performed to calculate the frequencies of the 7 different combinations of subsets using the Flowjo software.
Correlation between every bacterial genus/PCoA axis and immune markers was performed through the fit of a linear model for each combination of immune marker. The Benjamini–Hochberg[31] method was used for adjustment of multiple comparisons error.
2.6 Ethics approval and consent to participate
The study was approved by the Emory University IRB under the title “The Oral Metagenomics Study” (IRB00048095). All participants provided informed consent.
3 Results
This was a cross-sectional study including 50 participants. Participant population characteristics and dental exam information are shown in Table S1a, S1b, and S1c, respectively. Each participant contributed saliva, tooth samples from 2 teeth, and 2 cheek mucosa samples. Of these participants, 40 (80%) were HIV+. Only one of these participants was ART naive. Only 8 of the total participants had a detectable viral load, and 3 of these 8 had a viral load that was less than 1000 copies per mL. Although HIV+ participants tended to be homosexual older men compared to the HIV– participants, the study population was well balanced with regard to PD status. A total of 18 (36%), 16, and 16 (32%) of the participants presented none/mild (N-PD), moderate (M-PD), and severe (S-PD) PD, respectively. There were no significant differences in the salivary flow rate, MDF (missing, decayed, filled teeth), or salivary buffering capacity between N and M/S-PD participants. 242 of the samples provided more than 1000 sequences and were used for downstream analyses. Of these, 94/100, 49/50, and 99/100 were cheek, saliva, and teeth samples, respectively. A total of 148/408 (36.3%) different bacterial genera provided more than 100 counts and were kept for further analyses.
3.1 Microbiome analysis
When all sample sites were analyzed together, bacterial diversity but not richness was consistently higher in tooth samples than in both cheek and saliva samples through all PD stages and in both HIV-positive and -negative participants (P < 0.001 for all comparisons, Fig. 1 and Fig. S1). Importantly, greater similarity was found in the same participant teeth and cheek samples (Fig. S6) than between participants. Alpha diversity measures regarding HIV infection were less consistent. HIV– samples showed higher richness measures only in the M-PD group (P < 0.05), whereas this tendency was reversed in diversity for the S-PD group (P < 0.01). Additionally, S-PD was associated with higher richness and diversity measures, but only in cheek samples.
Figure 1 Richness (observed species, Chao1 indices) and diversity (Shannon and Simpson indices) for different sampling sites by HIV infection status (A), HIV infection status by sampling site (B), and by PD and HIV infection status (C). HIV = human immunodeficiency virus, PD = periodontal disease.
PCoA ordination analyses showed a clear differentiation of microbial structure among body sites sampled (adonis test P value = 0.001, R2 = 0.20, Fig. 2), whereas HIV status and PD severity showed a statistically significant but marginal contribution to microbial structure differentiation (HIV: adonis P value = 0.008, R2 = 0.01, PD: adonis P value = 0.092, R2 = 0.01, Fig. S2), which was of similar magnitude to that of ethnicity (EthnicGroup adonis P value = < 0.005, R2 = 0.03) and sexual behaviour (SexBeh, adonis P value = <0.05, R2 = 0.02). According to stratified analysis these factors lost statistical significance on saliva, but not for cheek and teeth samples, whereas habits such as tobacco (adonis P value = <0.05, R2 = 0.05) and soda drink (adonis P value = <0.05, R2 = 0.06) consumption became statistically relevant. Ethnicity had the largest effect on teeth (adonis P value< = 0.01, R2 = 0.07) and cheek (adonis P value< = 0.001, R2 = 0.17) samples. Importantly, PD effects on oral microbiome were only significant for cheek (adonis P value< = 0.01, R2 = 0.06) but not for teeth or saliva samples, whereas HIV infection exerted a similar effect on cheek (adonis P value = 0.05, R2 = 0.02) and teeth samples (adonis P value<0.01, R2 = 0.03) but had no significant impact in saliva samples.
Figure 2 PCoA ordination analysis. Axes 1 and 2 capture 58% of the variance observed in the microbiome structure of all oral samples. According to PERMANOVA analysis, sampling site explained 20% of the oral microbiome structure (adonis test P value = 0.001, R2 = 0.20). 10% was evenly explained by other factors such as HIV infection (adonis test P value = 0.001, R2 = 0.01), ethnicity (adonis test P value = 0.001, R2 = 0.03), sexual behaviour (adonis test P value = 0.006, R2 = 0.02) and periodontal disease severity (adonis test P value = 0.003, R2 = 0.02). HIV = human immunodeficiency virus, PCoA = principal coordinates analysis.
Firmicutes was the most abundant phylum in all sampling sites followed by Actinobacteria, Bacteroidetes, Fusobacteria, and Proteobacteria, whose relative abundance order changed depending on sampling site (Fig. S3). Differences linked to HIV infection affected the Proteobacteria phylum, which was overabundant in HIV+ cheek (log 2 Fold-Change (log 2 FC)):1.08, Padj<0.0051) and teeth samples (log2FC:1.23, Padj<0.005),(Table S2) although there was no correlation of Proteobacteria abundance with viral load (VL) or CD4+ counts within the HIV-positive group (data not shown). Changes in phylum abundance with PD severity were more frequent. Synergistetes and Spirochaetae, both low abundant phyla, were consistently found to be more abundant in teeth, cheek, and saliva samples from the S-PD group versus N-PD, whereas Proteobacteria and Firmicutes phyla had a 2-fold reduction in cheek and saliva, but not in teeth S-PD affected samples.
HIV infection status was also associated with relative abundance changes of different bacterial genera. In particular, Neisseria and genera of the unclassified Neisseriaceae family were 4-fold more abundant in samples from HIV+ participants (log 2 FC = 1.84, Padj < 0.001, Table 1 and Fig. 3). Interestingly, this change in abundance was consistent through the different anatomical sites, although with different levels of significance as well as in the age and sexual behavior adjusted model (Table S5). Importantly, the Neisseria genus was also more abundant in samples from HIV+ participants through varying severity of PD, with similar fold-change values (log 2 FC) with respect to HIV– samples (see Table S3 & S4). Interestingly, Aggregatibacter genus abundance was higher in HIV+ N-PD samples (log 2 FC = 2.02, Padj < 0.005), but not in more advanced PD stages. Furthermore, 3 different genera (Abiotrophia, Rothia and unclassified Pasteurellaceae) that were uniquely enriched in cheek HIV+ N-PD samples, were otherwise overabundant in M-PD and S-PD teeth, but not saliva samples, suggesting a tissue shift of these genera along PD severity (Table S4). Other genera were found to be differentially abundant in either HIV+ teeth, saliva or cheek samples, but not generally, in such a way that HIV associated changed in microbial genera were found to be localized to single site/PD severity combinations.
Table 1 Genus level significant changes in abundance associated with HIV infection (HIV+) stratified by severity of PD.
Figure 3 Classified differential abundant genera between HIV+ and HIV– samples. Log 2 Fold Change is plotted on the X-axis. Phyla is indicated using color codes. Point size indicates the mean count for a particular genus on the whole sample set. HIV = human immunodeficiency virus.
Of the bacterial genera that are traditionally linked to PD[6] only Treponema genus was found to be overabundant in S-PD when compared to N-PD, when HIV infection was not considered, in both cheek (log 2 FC = 1.83, Padj < 0.005) and saliva (log 2 FC = 2.6, Padj < 0.001) samples, albeit in very low abundance (Table 1). These were accompanied by other genera, underlining the complex multicomponent nature of microbiome disbyosis with PD. Cheek samples showed the greatest number of differentially abundant bacterial genera along PD severity. Severe PD was associated, with a 2-fold reduction in highly abundant Streptococcus, Veillonella genera, and unclassified Pasteurellaceae family, whereas the 2 latter also showed similar under-abundance in saliva samples. Interestingly, the Neisseria genus was not found to be over- or under-represented in different PD stages.
3.2 Immune activation
Immune activation markers were available for a subset of 24 participants (8 N-PD, 8 M-PD, and 8 S-PD), whereas CD4 counts were only available for the subset of HIV-positive participants. Despite the fact most HIV-positive participants were receiving ART (see Table S1c), there was a strong association between HIV infection and immune activation, proliferation, and translocation markers (Fig. 4). This association was also found for CD4+ T cell counts and PD severity, showing a higher CD4+ count in N-PD participants, indicating a deterioration of the immune system both with moderate or severe PD. Interestingly, immune markers for proliferation were found to be higher both for the CD8 and CD4 T-cell subset in moderate M-PD than in both N-PD and S-PD, whereas markers for cell activation were not significantly differently across PD severity.
Figure 4 Immune activation, proliferation, and bacterial translocation markers according to the HIV infection and the PD stage. Y-axis values for immune markers represent proportion of CD4/CD8 population resulting of the gate strategy described in the plot title. CD4+ T-cell counts were unavailable for HIV– subjects. HIV = human immunodeficiency virus, PD = periodontal disease.
Immune activation markers were correlated with both genus abundance and projection of each of the samples against each of the first 3 ordination PCoA axes from the analysis segregated by sampling. A strong and significant correlation was found between HLA-DR+/Ki67+/CD38- cell subset and increasing abundance of Streptococcus genus (R2 = 0.61, Padj (FDR)<0.001, Fig. S4), only in saliva samples. In addition, none of the immune activation markers nor CD4+ T cell counts showed a significant correlation with any of the PCoA axes (data not shown) in any sampling site type. Interestingly, a 4-fold depletion of the Streptococcus genus was associated with HIV+ status in cheek S-PD samples. Although this depletion in cheek samples was not accompanied by significant changes in teeth or saliva S-PD samples, there was a general and significant trend towards Streptococcus depletion globally in S-PD HIV+ participants, whereas this genus was enriched in N-PD HIV+ participants.
3.3 Functional analysis
Functional analysis using the PiCRUSt inferred gene content also revealed major differences among sampling sites (Fig. S5). Teeth samples were enriched in cell motility pathways including chemotaxis and flagellar assembly, probably reflecting tooth biofilm formation. Genes within carbohydrate, vitamins, and lipid metabolism pathways were enriched in cheek samples. No significant differences in the functional gene content could be consistently linked to HIV infection in any PD severity or anatomic site. In combination with taxonomical analysis and the lack of correlation between HIV-linked bacterial genera and inflammation, this underlines the nonpathogenic character of the increased abundance of Neisseria genus and suggests the pathobiont nature of this genus in the context of HIV-associated PD.[37]
4 Discussion
This study adds important information to the paucity of publications examining the effect of HIV status on the human oral microbiome. As reported in other studies, major differences in microbiome structure and composition were associated with the anatomic sampling site of patients, underscoring the great diversity and biogeography within the oral microbiome.
Globally, PD severity was associated with a broader change within the oral microbiome than HIV infection. PD affected a high number of bacterial genera, and these changes were of greater magnitude due to the mean abundance of affected genera and showed specificity for the sampling site. For instance, Veillonella and Streptococcus, both dominant genera in cheek mucosa and saliva, had a 2-fold reduction, thus contributing to alpha-diversity increases detected in these 2 sampling sites with PD severity. In addition, low-abundant members of the Treponema genus belonging to the PD-associated red complex were also enriched in severe PD samples. Conversely, differences in Tannerella and Porphyromonas genera along PD were not observed in this dataset. In our study, these genera were found at very low abundances (0.2% and 2.3%, mean abundances, respectively) in teeth and not differentially abundant along PD severity. Interestingly, Hong et al described 2 types of microbial communities in a PD-affected general population. Only one of them was enriched in Tannerella and Porphyromonas and associated to PD severity.[38] Our results may indicate that HIV infection may result in a bias in the dysbiotic pathway toward PD.
HIV infection solely affected a few low-abundance bacterial genera, including Neisseria, which was 4-fold enriched in 3 independent oral sampling sites. The Neisseria genus has been previously found to be depleted in the subgingival plaque of smokers,[39] whereas other sampling sites have not been explored to this respect. In our dataset, smoking also had a depleting effect in the 3 different sampling sites. Although it cannot be absolutely ruled out that other confounding factors may be affecting our results, our study design was well-balanced and no significant interaction between smoker status and HIV infection was detected. Furthermore, the Neisseria genus enrichment was still associated with HIV infection in the nonsmoker subset (log 2 FC = 1.48, Padj<0.05), although statistical significance was marginally lost for the smoker smaller subset (log 2 FC = 1.1, Padj = 0.15). Also, sexual behavior has been linked to changes in the gut microbiome.[40] Although, in our dataset, HIV infection was enriched in men who had sex with men, this factor alone had a small effect on the oral microbiome structure (adonis test R2 = 0.02, Pr (>F) = 0.032) and the age and sexual behavior adjusted model provided a similar picture in bacterial differential abundance than the unadjusted one. Several species that belong to the Neisseria genus such as N bacilliformis and N elongata, considered as nonpathogenic[41,42] or related to PD,[16] have been associated with respiratory and oral cavity infections.[43] The role of oral Neisseria genus in HIV infection has attracted limited attention; the few published studies using distinct sampling techniques had contradictory results. Recently, N. elongata was found to be enriched in the salivary microbiome of AIDS patients,[18] but minor nonsignificant changes in this genera were found between HIV-positive participants before and after commencing ART and when compared to seronegative participants in another study.[19] In addition, colonization of N flavescens was lower in the lingual microbiome of HIV-positive patients receiving ART than in HIV-negative controls.
Of note, no relation between Neisseria and Neisseriaceae family abundance and immune activation markers could be detected. This could be explained both by the commensal nonpathogenic nature of Neisseria genus and by a potential competitive advantage in HIV+ participants that affected all sampling sites, even under ART.
5 Conclusions
PD and HIV infection were associated with significant microbiome changes within anatomic sampling sites. Three major findings were uncovered in this analysis: (1) Neisseria spp. appeared to be enriched in HIV-positive participants compared to HIV-negative participants across all sampling sites, (2) among HIV+ participants Abiotrophia, Rothia, and unclassified Pasteurellaceae were enriched in M-PD and S-PD compared to N-PD, and (3) Treponema spp. were enriched in S-PD compared to N-PD for all participants. PD moderate severity was associated with higher CD4 and CD8 proliferation; however, associations with other inflammatory parameters relevant for HIV pathogenicity were not found.
Although Neisseria genus was found to be enriched in the oral microbiome of HIV-positive participants, it showed no linkage to either inflammation, immune parameters, or functional gene content. Relative abundance increase was consistently found in teeth, cheek mucosa, and saliva samples and in samples from participants with mild or no PD, but also moderate and severe PD. Changes in other bacterial genera related to HIV infection were scarce and had a very limited effect on bacterial diversity.
Acknowledgments
The authors would like to express our deepest admiration and appreciation for the patients who participated in the study and the work of the Ponce Clinic at Grady Memorial Hospital for their commitment to improve patient care and support research. The tremendous contributions on the part of the Oral Health Center staff have been essential to the success of this study. The authors acknowledge the contribution study coordinators, Lebo Tsotetsi, and Ulochi Nwagwu as well as the dental staff, Anthony Rozier and Spencer Waddell. They thank the IGTP Bioinformatics core facility staff for their contribution to this publication.
This work was presented in part at 2015 International Human Microbiome Conference (IHMC 2015), March 31st–April 2nd, Luxembourg, Poster #292.
Supplementary Material
Supplemental Digital Content
Supplementary Material
Supplemental Digital Content
Abbreviations: HIV = human immunodeficiency virus, CDC/AAP = Centers for Disease Control/American Academy of Periodontology, KEGG = Kyoto Encyclopedia of Genes and Genomes, LEFSE = LDA effect size, PCoA = principal coordinates analysis, PICRUSt = Phylogenetic Investigation of Communities by Reconstruction of Unobserved States, PD = periodontal disease, HAART = highly active antiretroviral therapy, VL = viral load.
TDR and VCM contributed equally.
Data availability: Metagenomics raw sequencing data along with sample level metadata have been deposited using the NCBI/SRA Web service and compliance to MIMARKS standard. Data can be accessed using SRA accession SRP079702.
Funding: This work was supported by the Emory University Center for AIDS Research (CFAR) (V.C.M., P30AI050409). TR acknowledges funding from Emory University Development Funds. M.N-J, J.R, Y.G. and R.P acknowledge funds from the Gala contra la SIDA 2013 and 2014 editions, the Nit per la Recerca a la Catalunya Central 2015 edition and the Red de investigación en SIDA, RD12/0017/0002 as part of the Plan Nacional R + D + I and cofinanced by the Instituto de Salud Carlos III (ISCIII)-Subdirección General de Evaluación y el Fondo Europeo de Desarrollo Regional (FEDER). J.R. is supported through a grant for pre-doctoral studies from Noel Alimentaria to the University of Vic (UVic-UCC).
Authorship: VCM and TDR conceived and designed the study. DR recruited the study participants, performed their clinical evaluations and collected samples. VCM, DR, MLN, and SM collected and organized data. DR and JMP processed samples, prepared DNA libraries, and performed sequencing. SK performed the inflammation analysis. MN-J, YG, EVH, and SJJ performed bioinformatics sequence analysis. JR performed statistical analysis (JR under the supervision of MN-J and RP). YG ran functional inference analysis under the supervision of MN-J, RP, VCM, and TDR interpreted results. MN-J, RP, TDR, and VCM wrote manuscript, which was reviewed, edited, and approved by all authors.
The authors have no conflicts of interest to disclose.
Supplemental Digital Content is available for this article.
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Medicine (Baltimore)Medicine (Baltimore)MEDIMedicine0025-79741536-5964Wolters Kluwer Health 28328801MD-D-16-0593310.1097/MD.0000000000006127061274500Research ArticleObservational StudyInfluence of polymorphisms in the Wnt/β-catenin pathway genes on hepatocellular carcinoma risk in a Chinese Han population Li Qing-Min MMaZhang Feng-Qin MMbLi Ya-Feng MMc∗Xian Qing-Jie MMaZhang Yan-Qiang MMaLi Peng MMaFan. Huitao a Department of Clinical Laboratory, Liaocheng People's Hospital and Liaocheng Clinical School of Taishan Medical Universityb Department of Infusion and Injuction Room, Liaocheng People's Hospital and Liaocheng Clinical School of Taishan Medical Universityc Department of Gastroenterology, Liaocheng People's Hospital and Liaocheng Clinical School of Taishan Medical University, Liaocheng, Shandong Province, China.∗ Correspondence: Ya-Feng Li, Department of Gastroenterology, Liaocheng People's Hospital and Liaocheng Clinical School of Taishan Medical University, 67 Dongchang Road, Liaocheng, Shandong Province 252000, China (e-mail: yafengli9980@163.com)3 2017 24 3 2017 96 12 e61273 10 2016 27 12 2016 17 1 2017 Copyright © 2017 the Author(s). Published by Wolters Kluwer Health, Inc.2017This is an open access article distributed under the terms of the Creative Commons Attribution-Non Commercial License 4.0 (CCBY-NC), where it is permissible to download, share, remix, transform, and buildup the work provided it is properly cited. The work cannot be used commercially without permission from the journal. http://creativecommons.org/licenses/by-nc/4.0Abstract
The Wnt/β-catenin pathway plays a vital role in initiating and sustaining hepatocellular carcinoma (HCC). However, few studies have investigated polymorphisms in the Wnt/β-catenin signaling pathway genes in the Chinese Han population. The aim of the present retrospective study was to investigate the correlations between polymorphisms of the Wnt/β-catenin signaling pathway genes (CTNNB1 and WNT2) and HCC susceptibility, development, and progression.
Twenty tagging single nucleotide polymorphisms were chosen from HapMap data and genotyped in 320 patients with HCC, 320 chronic hepatitis B virus (HBV)-infected patients without HCC (N-HCC, including 95 liver cirrhosis, 164 chronic hepatitis B, and 61 asymptomatic HBV carriers), and 320 healthy controls. Associations between polymorphisms in the 2 Wnt/β-catenin signaling pathway genes (CTNNB1 and WNT2) and HCC susceptibility, development, and progression were investigated.
Genotype AA (P = 0.002, odds ratio [OR] = 2.524) and allele A (P = 0.0003, OR = 1.613) of the WNT2 rs4730775 polymorphism were associated with HCC susceptibility compared with healthy controls. Genotype GA (P = 0.001, OR = 0.567) and allele A (P = 0.002, OR = 0.652) of rs3864004, and genotype AG (P = 0.0004, OR = 0.495) and allele G (P = 0.001, OR = 0.596) of rs11564475 in the CTNNB1 gene were correlated with HCC compared with N-HCC patients. These findings were consistent in dominant and recessive models. Multidimensionality reduction analysis revealed that interactions among rs3864004, rs11564475, and rs4730775 were significantly associated with HCC compared with N-HCC patients. The polymorphism rs4135385 of CTNNB1 genotype GA was associated with a higher risk for Stage III + IV HCC (modified Union for International Cancer Control) (P = 0.001, OR = 2.238).
Genetic polymorphisms in the WNT2 and CTNNB1 genes were closely associated with HCC risk and progression in a Chinese Han population.
Keywords
CTNNB1genetic polymorphismhepatocellular carcinomaWNT2OPEN-ACCESSTRUE
==== Body
1 Introduction
Hepatocellular carcinoma (HCC) is the third most common cause of cancer-related deaths worldwide, accounting for 70% to 85% of all liver cancers. About 75% to 80% of HCC cases are caused by chronic hepatitis B virus (HBV) or hepatitis C virus infection.[1] China is an endemic region for chronic HBV infection with 94 million patients, and approximately half of the global HCC patients are in China.[2,3] Overall, 2% to 3% of chronic HBV-infected patients develop HCC.[4] Male sex,[5,6] old age, inflammation,[7] and cirrhosis are known risk factors for HCC.[5,8,9] Moreover, single nucleotide polymorphisms (SNPs) of host genes have been found to be correlated with the development and progression of HCC.[10–12]
The Wnt/β-catenin pathway plays a vital role in initiating and sustaining HCC. It plays an important role in embryogenesis and in adult tissue homeostasis.[13] The CTNNB1 gene encodes β-catenin protein, which plays an important role in tissue regeneration, proliferation, differentiation, and development.[14,15] Wnt2 is a member of the Wnt/β-catenin pathway, and has been reported to be associated with multiple cancers.[16–19] Although the Wnt/β-catenin signaling pathway is important for HCC, few studies have investigated polymorphisms in the Wnt/β-catenin signaling pathway genes in the Chinese Han population.
The aim of the current retrospective study was to investigate the correlations between variants in 2 Wnt/β-catenin signaling pathway genes (CTNNB1 and WNT2) and HCC susceptibility and progression. SNP–SNP interactions were analyzed by multidimensionality reduction (MDR).
2 Methods
2.1 Patients
In the present study, we obtained blood samples from unrelated Chinese Han patients at the Liaocheng People's Hospital, Liaocheng, Shandong Province, China between January 2012 and December 2015. A total of 960 individuals were selected for the study, including 320 chronic HBV-infected patients with HCC, 320 chronic HBV-infected patients without HCC (N-HCC, including 95 liver cirrhosis, 164 chronic hepatitis B [CHB], and 61 asymptomatic HBV carriers), and 320 healthy controls (HC). All the HCC and N-HCC cases showed more than 6 months of sero-positivitiy for hepatitis B surface antigen. We diagnosed HCC and liver cirrhosis patients according to clinical and biological criteria, which were confirmed by iconography examination (magnetic resonance imaging or computed tomography). Asymptomatic HBV carriers were defined as patients with chronic HBV infection and persistently normal liver biochemical parameters. CHB patients were defined as chronic HBV-infected patients with abnormal liver biochemical parameters (intermittent or persistent elevations of bilirubin or aminotransferases), and no evidence of HCC or liver cirrhosis. The HC group was defined as individuals with negative HBV sero-markers, no history of hepatitis, normal liver function, and no cancers or other disorders.
Each HC individual was matched with an HCC patient and an N-HCC patient by sex. The study protocol was approved by the ethics committee of Liaocheng People's Hospital. Written informed consent was obtained from all subjects.
2.2 Tagging SNP selection
Twenty tagging SNPs (tgSNPs) were chose from the CTNNB1 and WNT2 genes among data in the International HapMap Project, release27 (http://hapmap.ncbi.nlm.nih.gov) for the CHB population. The exclusion criteria were an r2 value < 0.8 and a minimum allele frequency <0.05. Nonsynonymous SNPs or functional SNPs in the literature or in the National Center for Biotechnology Information database were selected initially. The F-SNP program was used to determine the functional SNPs (http://compbio.cs.queensu.ca/F-SNP/).
2.3 DNA purification and SNP analysis
Wizard Genomic DNA Purification Kit (Promega; Madison, WI, USA) was used to obtain genomic DNA samples from peripheral blood leukocytes, according to the manufacturer's instructions. A NanoDrop spectrophotometer was used to measure the DNA concentration. DNA samples were diluted to 50 ng/μL and stored at −80°C for genotyping analysis. We used IplexGOLD chemistry on a SEQUENOM mass spectrometer (Sequenom Inc, San Diego, CA) to genotype the selected 20 tgSNPs. A negative control and duplicate samples were set in every 96-well plate for quality control.
2.4 SNP–SNP interaction analysis
Potential interactions among SNPs were tested by MDR (version 3.0.2), which is a nonparametric program. The program contains permutation testing and cross-validation. MDRpt (version 1.0_beta_2) was used for permutation testing to determine statistical significance. Significant interactions were defined according to P < 0.05. The best model is one that shows a cross-validation consistency (CVC) ≥ 9 and the largest testing balance accuracy (TBA). The MDRpt and MDR programs are freely available from http://www.epistasis.org.
2.5 Statistical analysis
HCC risk was investigated according to the genotypes and alleles of CTNNB1 and WNT2 in comparison to the control groups. We tested for Hardy–Weinberg equilibrium in the HC group with IHG program (http://ihg.gsf.de/cgi-bin/hw/hwa1.pl). The Mann–Whitney U test or χ2 test was used to test differences in age, sex, or clinical characteristics between groups. We used recessive or dominant genetic models to evaluate the associations of each genotype with HCC. The relative risks of SNPs for HCC were investigated with binary logistic regression. Haploview software (v4.2) was used to identify haplotype frequencies. Bonferroni correction was used to correct P values for multiple testing (0.05/20 = 0.0025). Statistical calculations were carried out by SPSS 21.0 (Chicago, IL), and P < 0.0025 was considered to indicate statistical significance.
3 Results
Two SNPs (rs2293302 from CTNNB1 and rs733153 from WNT2) were excluded from the analysis owing to genotyping success rates <92%. The other 18 SNPs selected were all in accordance with Hardy–Weinberg equilibrium in the HC group.
3.1 Characteristics of the study population
Characteristics of the study population among the HCC, N-HCC, and HC groups are shown in Table 1. Sex and age did not differ significantly among the 3 groups (P > 0.05). The HCC group had significantly higher levels of HBV DNA, total bilirubin (TBIL), aspartate aminotransferase (AST), and alanine aminotransferase (ALT) compared with the HC group. However, the levels of HBV DNA, TBIL, AST, and ALT did not differ significantly between the N-HCC and HCC groups.
Table 1 Demographic and clinical characteristics of the study population.
3.2 Correlations of SNPs with HCC
Compared with the HC group, the rs4730775 genotype AA (P = 0.002, odds ratio [OR] = 2.524) and allele A (P = 0.0003, OR = 1.613) from the WNT2 gene showed significant differences in the HCC group. Significant associations of this SNP with HCC susceptibility were also detected in the dominant and recessive genetic models (P = 0.005, OR = 1.576; P = 0.005, OR = 2.272) (Table 2).
Table 2 Association of WNT2 (rs4730775) in HCC risk.
Compared with the N-HCC group, the rs3864004 genotype GA (P = 0.001, OR = 0.567) and allele A (P = 0.002, OR = 0.652) and the rs11564475 genotype AG (P = 0.0004, OR = 0.495) and allele G (P = 0.001, OR = 0.596) of the CTNNB1 gene showed significant differences in the HCC group. Significant associations of these SNPs with HCC were also detected in the dominant and recessive genetic models (P = 0.001, OR = 0.574; P = 0.0005, OR = 0.524) (Table 3).
Table 3 Association of CTNNB1 (rs3864004 and rs11564475) in HCC risk.
3.3 Correlations of SNPs with HCC tumor stage
Genotype GA of the rs4135385 polymorphism of CTNNB1 was associated with a higher risk for Stage III + IV HCC (modified Union for International Cancer Control) (P = 0.001, OR = 2.238). This finding was confirmed in the dominant model (P = 0.001, OR = 2.207). We did not find any other SNPs associated with HCC tumor stage (Table 4).
Table 4 Association of CTNNB1 rs4135385 in HCC tumor stage.
3.4 MDR for SNP–SNP interactions
MDR was performed to analyze the SNP–SNP interactions. Since rs4730775, rs3864004, and rs11564475 were associated with HCC, we carried out MDR for these 3 SNPs with HCC as the case group and HC or N-HCC as the control group. In this analysis, we found 1-way (rs3864004), 2-way (rs11564475 and rs4730775), and 3-way (rs3864004, rs11564475, and rs4730775) interactions in the HCC versus N-HCC comparison (Table 5). The best model was that for the 3-way interaction among rs3864004, rs11564475, and rs4730775 (TBA of 0.5938 and CVC 10/10; P < 0.001) (Fig. 1).
Table 5 MDR interaction analysis between SNPs in N-HCC versus HCC.
Figure 1 Interactions among SNPs in relation to HCC development. Interactions among SNPs in HCC versus N-HCC. Values in nodes represent the main effect. Values between nodes represent the interaction effect. HCC = hepatocellular carcinoma, N-HCC = chronic HBV-infected patients without HCC, SNP = single nucleotide polymorphism.
4 Discussion
In the present study, 20 tgSNPs from the WNT2 and CTNNB1 genes were genotyped in a Chinese Han population. One SNP of the WNT2 gene (rs4730775) and 2 SNPs of the CTNNB1 gene (rs11564475 and rs3864004) were found to be correlated with HCC. Moreover, rs4135385 of the CTNNB1 gene was associated with HCC tumor stage. Interactions among the 3 SNPs (rs3864004, rs11564475, and rs4730775) showed an association with HCC risk.
Accumulating evidence has revealed that Wnt/β-catenin signaling plays an important role in hepatic carcinogenesis.[20] Polymorphisms of CTNNB1 were reported to be associated with prostate cancer,[21] breast cancer,[22] colorectal cancer,[23] and gastric cancer.[24] In a Korean population, CTNNB1 polymorphisms were suggested to be involved in tumor development and survival of HBV-associated HCC patients.[25] However, there are no previous studies related to polymorphisms in CTNNB1 with HBV-related HCC patients in the Chinese Han population. In the present study, we found that genetic polymorphisms of CTNNB1 (rs11564475 and rs3864004) were associated with HCC development. rs11564475 is located in the intron region (http://www.ncbi.nlm.nih.gov/projects/SNP/snp_ref.cgi?rs=11564475) and rs3864004 is located in the promoter region (http://www.ncbi.nlm.nih.gov/projects/SNP/snp_ ref.cgi?rs=3864004) of CTNNB1. The functional prediction scores (F-SNP) for the 2 SNPs were 0.268 (rs11564475) and 0.065 (rs3864004). rs3864004 was reported to affect CTNNB1 expression levels in Korean asthma patients.[26] We speculate that both rs11564475 and rs386400 have functional effects and could influence the CTNNB1 expression level. However, direct experiments are needed to validate the functional consequences of these SNPs.
Although WNT2 is reported to be associated with multiple cancers, few studies have investigated polymorphisms of WNT2 with HBV-related HCC. In the present study, a polymorphism of WNT2 (rs4730775) was found to be correlated with HCC susceptibility. This is the first study to reveal that rs4730775 is associated with HBV-related HCC. rs4730775 is located in the 3′-untranslated region (http://www.ncbi.nlm.nih.gov/projects/SNP/snp_ref.cgi?rs=4730775) of WNT2. The functional prediction score (F-SNP) for rs4730775 was 0.5. We speculate that rs4730775 might have functional consequences and could affect the WNT2 expression level. However, direct experiments are needed to validate its function.
MDR analysis revealed that rs3864004 (CTNNB1), rs11564475 (CTNNB1), and rs4730775 (WNT2) might interact in HBV-related HCC development. Both gene products (CTNNB1 and WNT2) are involved in the Wnt/β-catenin signaling pathway. Therefore, all 3 SNPs might affect the expression of CTNNB1 and WNT2, resulting in HBV-related HCC development.
A previous study showed that mutation in the CTNNB1 gene could affect ß-catenin activity, which is correlated with liver tumor progression.[27] This is consistent with our finding that rs4135385 of the CTNNB1 gene was associated with HCC tumor stage. rs4135385 is located in the intron of CTNNB1 (http://www.ncbi.nlm.nih.gov/proje cts/SNP/snp_ref.cgi?rs=4135385), and the functional prediction score (F-SNP) for rs4135385 was 0.242. Introns play a vital role in the regulation of transcription or post-transcription processes to affect gene expression.[28,29] Therefore, SNPs in the intron region could affect this regulation. We speculate that rs4135385 might be a functional SNP to affect the expression of CTNNB1.
4.1 Limitations
There are 3 limitations of this study that should be taken into consideration. First, all included individuals (HC, N-HCC, and HCC patients) were recruited from only 1 hospital, which might result in selection bias. However, the distributions of all genotypes were in accordance with Hardy–Weinberg equilibrium in the HC group, except for 2 SNPs (rs2293302 from CTNNB1 and rs733153 from WNT2), which revealed that our subjects might be a good representation of the general population. Second, our study had a relatively small sample size, which might reduce the ability to find differences among groups in statistical analysis. Third, our study was a retrospective study, which had a less power to assess the risk of HCC development than a prospective study, in particular in cirrhotic HBV-infected patients (at high risk for liver cancer).
5 Conclusion
In conclusion, we found that polymorphisms in the Wnt/β-catenin signaling pathway genes (CTNNB1 and WNT2) are associated with HCC susceptibility and progression. In the future, more studies (especially prospective study) in multiple centers with larger sample sizes are needed to validate our findings that genetic polymorphisms in WNT2 and CTNNB1 are closely associated with HCC risk.
Abbreviations: ALT = alanine aminotransferase, AST = aspartate aminotransferase, CHB = chronic hepatitis B, CVC = cross-validation consistency, HBV = hepatitis B virus, HC = healthy controls, HCC = hepatocellular carcinoma, MDR = multidimensionality reduction, N-HCC = chronic HBV-infected patients without HCC, OR = odds ratio, SNP = single nucleotide polymorphism, TBA = Testing balance accuracy, TBIL = total bilirubin, TgSNP = tagging SNP.
The authors have no funding and conflicts of interest to disclose.
==== Refs
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Medicine (Baltimore)Medicine (Baltimore)MEDIMedicine0025-79741536-5964Wolters Kluwer Health 28328802MD-D-16-0462910.1097/MD.0000000000006160061607300Research ArticleObservational StudyCurative effect of neutral macroporous resin hemoperfusion on treating hemodialysis patients with refractory uremic pruritus Li Wen-Hong MDYin Yu-Min MDChen Hao MDWang Xiao-Dan MDYun He MDLi Hui MDLuo Jie MDWang Jin-Wen MD∗Tripathi. Durga Department of Kidney Disease, Yan’an Hospital Affiliated to Kunming Medical University, Nephrology, Kunming, China.∗ Correspondence: Jin-Wen Wang, Department of Kidney Disease, Yan’an Hospital Affiliated to Kunming Medical University, Nephrology, No. 245 people's east road, Kunming 650051, China (e-mail: drwang_16@163.com).3 2017 24 3 2017 96 12 e61607 7 2016 3 1 2017 26 1 2017 Copyright © 2017 the Author(s). Published by Wolters Kluwer Health, Inc.2017This is an open access article distributed under the terms of the Creative Commons Attribution-Non Commercial-No Derivatives License 4.0 (CCBY-NC-ND), where it is permissible to download and share the work provided it is properly cited. The work cannot be changed in any way or used commercially without permission from the journal. http://creativecommons.org/licenses/by-nc-nd/4.0Abstract
This study aims to investigate the efficacy and safety of neutral macroporous resin hemoperfusion in treating maintenance hemodialysis (MHD) patients with refractory uremic pruritus (RUP).
Ninety patients were enrolled and were randomly divided into 3 groups: control group, experiment 1 group, and experiment 2 group. Clinical symptom scores of skin itching were recorded before and at 4 and 8 weeks after the treatment. In addition, serum parathyroid hormone (PTH), calcium (Ca2+), phosphorus (P3+), and C-reactive protein (CRP) were detected; and the calcium–phosphorus product ([Ca] × [P]) was calculated to compare the curative effect.
VSA score, modified Duo pruritus score, and CRP: these indices decreased to some extent at 4 and 8 weeks after treatment in the 2 experiment groups, compared with pretreatment (P < 0.05); and differences among these 3 groups were statistically significant (P < 0.05). PTH, P3+, and [Ca] × [P]: these indices decreased to some extent at 4 and 8 weeks after treatment in the 2 experiment groups, compared with pretreatment (P < 0.05); and differences between the control and experiment 1 groups, as well as between the control and experiment 2 groups, were statistically significant (P < 0.05). However, the difference between the experiment 1 and experiment 2 groups were not statistically significant (P < 0.05).
The effects of HA330 and HA130 resin hemoperfusion apparatus on secondary hyperparathyroidism and the disorder of calcium and phosphorus metabolism are similar. The mechanism may be related to its strong adsorption effect, and its capacity to widely remove inflammatory mediators, immune mediators, and endotoxins.
Keywords
HA330 type resin hemoperfusionhemoperfusionintractable pruritus uremicmaintain the blood purificationOPEN-ACCESSTRUE
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1 Introduction
Uremic pruritus (UP) is a common complication in maintenance hemodialysis (MHD) patients, which seriously affects the quality of life of patients and reduces survival rate.[1,2] A study suggested that the degree of UP was not correlated with the length of dialysis, the number of weekly dialysis, primary renal diseases, gender, and age.[3] Most scholars considered that UP was mainly associated with the increase in parathyroid hormone (PTH) and β2-microglobulin (β2-MG).[4] At present, the application of a variety of blood purification methods (such as hemodiafiltration [HDF], hemoperfusion [HP], and HFHD) to improve the symptoms of UP in patients with MHD has achieved certain effects.[5–9] Different blood purification methods are commonly used in clinical practice.[10,11] The order of scavenging the efficiency of moderate- and macromolecular weight uremic toxins is HD + HP > HP > HDF > HF > HD (hemodialysis [HD]).[5] In recent years, HP technology has been widely used in many fields of clinical practice.[12] A number of studies have confirmed that HP can effectively remove PTH, β2-MG, and other moderate- and macromolecular weight uremic toxins,[5] and this technology has achieved good curative effects in improving refractory hypertension, refractory pruritus, and renal osteodystrophy. A study in China[13] revealed that a resin HP apparatus (RHA) can effectively remove iPTH and serum retinol-binding protein, and markedly improve skin itching. HDF can remove moderate-molecular-weight substances in plasma to a certain extent, such as iPTH, but its scavenging effect on the high-molecular complexes formed by retinol-binding protein, retinol, and prealbumin (in blood, retinol-binding protein binds with retinol and prealbumin at a ratio of 1:1:1 in a complex form) is not significant. Hence, it has a certain effect on skin itching. HD has no scavenging effect on serum iPTH and retinol-binding protein. At present, the most widely used RHA in China has the following characteristics:(1) All of these use neutral macroporous adsorption resin, the specific surface areas of the resin are all >1000 m2/g, the adsorption resin pore size is within 0 to 200 nm, some pore structures are over 10 nm, and there are obvious distribution peaks in the scope >50 nm. Due to the interaction between toxins and the hydrophobic groups, as well as the physical adsorption of the 3-dimensional mesh structures of the resin molecules, these apparatuses have an adsorption specificity that can effectively eliminate pathological molecules in blood, especially moderate- and macromolecular weight molecules.
(2) High mechanical strength, no particles falling off, safe, and reliable.
(3) High adsorption strength and large capacity.
(4) Different types of these apparatuses have relative adsorption specificity and high selectivity to the removal of substances.
(5) Good blood compatibility, few side effects, only a minority of patients had mild allergic reactions, hypotension, chills, shiver, and fever, and decreased white blood cells and platelets.
According to the characteristics of the pathogenic substances they can eliminate, these apparatuses can be divided into 5 models: HA130, HA230, HA280, HA330, and HA330-II. These apparatuses can be used in various clinical fields. HA130-RHA is used for the treatment of complications in MHD patients, especially for intractable itching and refractory hypertension.[12]
In the past 10 years, blood purification technology has made great progress and development, and various blood purification methods have been widely used in the treatment of UP. However, the incidence of UP remains very high. The epidemiology of UP has some statistical differences due to the sources of data. But its overall incidence is not optimistic. Narita et al[14] reported that, 50% to 90% of MHD patients had UP at varying degrees. The Japanese Dialysis Outcomes and Practice Patterns Study (JDOPPS) reveals that: the incidence of UP in patients undergoing MHD is 22% to 86% in Japan, among these patients 44% had moderate or severe itching.[2] Data from Israel reveal that, the incidence of UP in HD patients in the area is 66.0% to 74.3%, approximately 3/4 of patients have mild itching, and approximately 2/3 of patients have extensive skin itching.[15,16] The DOPPS I and DOPPS II reveal that, in MHD patients with UP, 42% to 45% patients have moderate to severe itching.[17] Data from Pakistan reveal that, 8% of MHD patients with UP have refractory itching in the area.[18] Risk of death was 17% higher in dialysis patients with pruritus than in other dialysis patients.[17] Despite the full dialysis and various treatment methods of choice, some patients continued to achieve unsatisfactory curative effects.[19] For the mechanism of UP, in recent years, people have considered that itching is not only a local skin disease, but a systemic inflammatory disease; and that this was closely related to the microinflammatory state in uremia patients.[20,14] A study[21] confirmed that itching did not alleviate even when PTH level decreased, and PTH level and mastocyte number did not significantly correlate with the presence of itching and itching degree. Furthermore, the level of serum inflammatory substances such as CXC chemokine receptor 3, CRP, IL-6, TNF-α, and gamma interferon are higher in UP patients than in non-UP patients.[19] In the clinical practice of using HP for the treatment of critically ill patients, the authors found that HA330-RHA can significantly improve the itching symptom in patients. This suggests that the active inflammatory state may play an important role in the pathogenesis of pruritus. By comparing the structural and functional characteristics between HA130-RHA and HA330-RHA, it was found that the former has structural characteristics mainly for the relative specific absorption of moderate- and macromolecular weight toxins produced in uremia, and that the removal of PTH and β2-MG was the most prominent. Furthermore, blood chamber volume was 110 ± 5 mL, and resin adsorption reached a saturation state when the treatment lasted for 2 hours. For the latter, resin gap size and the characteristics of the coating have been improved, its ability to selectively adsorb inflammatory mediators was enhanced, and the efficiency and specificity of removing macromolecular inflammatory mediators and endotoxins were high.[22] Furthermore, blood chamber volume was 185 ± 5 mL, and resin adsorption reached saturation state when the treatment lasted for 2.5 hours. A study has confirmed that this kind of macroporous neutral resin has a definite effect on the removal of inflammatory mediators such as TNF-α, IL-1, IL-6, IL8, and so on.[23] In this study, HA330-RHA was used. For RUP patients who achieved unsatisfactory curative effect after receiving a full HD and a variety of blood purification treatments, the combined treatment of HD and HA330-RHA was performed once every 2 weeks, in order to investigate its therapeutic effect. The authors consider that this is of important clinical significance.
2 Materials and methods
This study was conducted with approval from the Ethics Committee of Yanan Hospital Affiliated to Kunming Medical University in January 2009. Written informed consent was obtained from all participants.
2.1 Inclusion criteria of cases
From January 2009 to January 2016, 90 patients who were treated with MHD for more than 3 months at the blood purification center of Yan’an Hospital Affiliated to Kunming Medical University were included into this study. Inclusion criteria: patients diagnosed with UP;[24,25] patients who have received a variety of blood purification treatments for more than 1 month (including HDF, HFHD, and HA130-HP), and had small improvements on skin itching symptoms or frequent attacks. Exclusion criteria: patients with systemic diseases (the liver, gallbladder disease, allergies, asthma, and tumors), skin diseases (psoriasis and skin tinea diseases), and metabolic diseases experienced itchy skin. Patients who had contraindications to HP.
2.2 Experiment grouping
Ninety patients were randomly divided into 3 groups by sealed letters: control group (regular hemodialysis [RHD]), experiment 1 group (RHD + HA130-HP), and experiment 2 group (RHD + HA330-HP). The specific method was as follows: the words “control group” were written on 30 cards; in the same way, “experiment group 1” and “experiment group 2” were written on 30 cards, respectively; and all the cards were placed into 90 envelopes. Patients who met the inclusion criteria and were willing to attend the trial chose and opened 1 envelope. The patient was assigned into 1 group, according to the card in the envelope. If patients withdrew from the trial (lost rate of follow-up was controlled within 10%), the corresponding number of patients were added into the corresponding group, until 30 patients completed the trial in each group. In the control group, no patient withdrew from the experiment. In experimental group 1, 1 patient withdrew from the experiment (the patient began treatment on May 3, 2009 and withdrew on April 8, 2009); and in experimental group 2, 2 patients withdrew from the experiment (1 patient began treatment on October 7, 2011 and withdrew on October 27, 2011; another patient began treatment on June 25, 2013 and withdrew on July 17, 2013).
2.3 Therapeutic methods
All selected patients provided a signed informed consent on blood purification prior to treatment. Three groups of patients underwent MHD using a German BRAUN Dialog HD machine, a LOPS15 polysulfone membrane low-flux dialyzer (membrane area: 1.5 m2, ultrafiltration coefficient: 9.8 mL/hour mm Hg, Germany BRAUN), bicarbonate dialysate, and ultrapure dialysis water (double reverse osmosis). The frequency of dialysis was 3 times per week, and duration was 4 hours per time. Blood flow volume was 250 to 300 mL/min, and dialysate flow volume was 500 mL/min. Anticoagulation was conducted using low-molecular-weight heparin. Control group: RHD, dialysis frequencies 3 times per week, 4 hours per time, blood flow volume 250 to 300 mL/min, dialysate flow 500 mL/min. Experiment 1 group: on the basis of RHD, patients received HP once every 2 weeks (HP was performed during the last HD in even weeks). The HP apparatus used was the HA130-RHA (Zhuhai Jafron Biotechnology Inc.). The HP apparatus was set before the dialyzer in series, and blood flow volume was set at 180 to 200 mL/min. The RHA was removed after 2 hours of treatment (when resin adsorption reaches a saturation state), and HD was continued for 4 hours. Experiment 2 group: on the basis of RHD, patients received HP once every 2 weeks (HP was performed during the last HD in even weeks). The HP apparatus used was the HA330-RHA (Zhuhai Jafron Biotechnology Inc.). The HP apparatus was set before the dialyzer in series, and blood flow volume was set at 180 to 200 mL/min. The RHA was removed after 2.5 hours of treatment (when resin adsorption reached a saturation state), and HD continued for 4 hours. The experiment foundation treatment for patients in the 3 groups before and after the trial was relatively fixed: PTH >300 pg/L, and oral calcitriol soft capsules 0.25 g at approximately 0.5 g/time, once daily. Pulse therapy: PTH >500 pg/L, and oral calcitriol at 2.0 to 2.5 g/day, twice a week. During the trial, insulin, erythropoietin, calcium supplement, and antihypertensive drug treatments were adjusted according to the condition of the disease and its detection.
2.4 Observation indexes
Before and 4 and 8 weeks after treatment, itching was evaluated by visual analogue scale (VAS)[26] and modified Duo pruritus scores.[27] The specific method was as follows: for VAS scores, a vernier of approximately 10 cm in length was used, on which 1 side was marked with 10 scales, and the 2 ends were “0” and “10” ends, respectively. The “0” points represented no itching, and the “10” points represented unbearable itching. Patients faced the side with the scales, and marked their own degrees of itching between 0 and 10 points, according to their own judgement. Scores between 0 and 2 points were excellent, scores between 3 and 5 points were good, scores between 6 and 8 points were medium, and scores >8 were poor (Fig. 1). Modified Duo pruritus scores: doctors evaluated the degree of itching according to the extent of scratching, distribution range, frequency of attacks, and sleep disturbances (Table 1). At the same time, exsanguinate assay for PTH, Ca2+, P3+, and CRP levels was conducted; and [Ca] × [P] was calculated.
Figure 1 Visual analogue scale.
Table 1 Modified Duo pruritus score system (0–40 score).
2.5 Statistical methods
Statistics analysis was performed using SPSS 20.0 software. The basic description of data was conducted using mean ± standard deviation, rate, and a correlation graph. Hypothesis testing was performed using 2 independent samples t-test, X2 test, and repeated measures analysis of variance (ANOVA). P < 0.05 was considered statistically significant.
3 Results
3.1 Comparison of the general information of subjects
The comparison was conducted using the variance test of a complete and randomly designed data. Differences in age, urea nitrogen, creatinine, and dialysis age among the 3 groups of patients were not statistically significant (P > 0.05) (Table 2).
Table 2 Comparison of the basic condition of patients in 3 groups.
3.2 Comparison of clinical test indices among the 3 groups before and 4 and 8 weeks after treatment
Repeated measures ANOVA:(1) Ca2+, test of within-subject effect: F = 2.625, P = 0.101; test of intersubject effect: F = 0.647, P = 0.424. These results revealed that: with the extension of treatment, the differences between pre- and posttreatment among the 3 groups were not statistically significant (P > 0.05). Hence, it can be considered that differences in the effects of the treatments in the 3 groups on Ca2+ metabolism were not statistically significant.
(2) PTH, P3+, and [Ca] × [P], test of within-subject effect: P < 0.05; test of intersubject effect, P < 0.05. These results revealed that: with the extension of treatment, PTH, P3+, and [Ca] × [P] decreased to a certain extent in these 2 experimental groups; pairwise comparison using LSD t test revealed that these decreases were significantly prominent in the 2 experimental groups than in the control group (P < 0.05), and the difference between these 2 experimental groups was not statistically significant (P > 0.05). It can be considered that the removal of PTH and P3+ and the improvement of [Ca] × [P] were better in these 2 experimental group than in the control group, and the effects between these 2 experimental groups were not different.
(3) CRP, test of within-subject effect: F = 53.840, P < 0.001; test of intersubject effect: F = 1211.319, P < 0.001. These results revealed that: with the extension of the treatment, CRP decreased to a certain extent in these 2 experimental groups; pairwise comparison using LSD t test revealed that the differences among these 3 groups were statistically significant (P < 0.05), and the decreases were significantly prominent in the 2 experimental groups than in the control group (P < 0.01).
After 8 weeks of treatment, the decrease was significantly prominent in experimental group 2 than in experimental group 1 (P < 0.05). It can be considered that CRP could be effectively reduced in these 2 experimental groups, and this effect was better in experimental group 2 (Table 3).
Table 3 ANOVA of repeated data of clinical indicators changes before and after treatment with patients in 3 groups.
3.3 Pruritus score comparison among the 3 groups before and 4 and 8 weeks after treatment
3.3.1 Comparison of VSA scores
Repeated measures ANOVA: test of within-subject effect: F = 393.645, P < 0.001; test of intersubject effect: F = 17.528, P < 0.001. These results revealed that: with the extension of the treatment, VSA scores decreased to a certain extent in these 2 experimental groups. Pairwise comparison using LSD t test revealed that the differences among these 3 groups were statistically significant (P < 0.05), and these decreases were significantly prominent in these 2 experimental groups than in the control group (P < 0.05, P < 0.01). After 8 weeks of treatment, these decreases were significantly prominent in experimental group 2 than in experimental group 1 (P < 0.05). It can be considered that these itching symptoms could be effectively improved in these 2 experimental groups, and this effect was best in experimental group 2 (Fig. 2).
Figure 2 Visual analogue scale (VAS) score before treatment, 4 and 8 weeks of 3 groups (score). Application of duplicate variance analysis: test of within-subject effect, F = 393.645, P < 0.001; test of intersubject effect, F = 17.528, P < 0.001; comparison of each 2 groups, they all have difference (P < 0.05).
3.3.2 Comparison of modified Duo pruritus scores
Repeated measures ANOVA: test of within-subject effect: F = 320.873, P < 0.001; test of intersubject effect: F = 25.395, P < 0.001. These results revealed that: with the extension of the treatment, modified Duo pruritus scores decreased to a certain extent in these 2 experimental groups. Pairwise comparison using LSD t test revealed that the differences among the 3 groups were statistically significant (P < 0.05), and these decreases were significantly prominent in these 2 experimental groups than in the control group (P < 0.05, P < 0.01). After 8 weeks of treatment, these decreases were significantly prominent in experimental group 2 than in experimental group 1 (P < 0.05). It can be considered that these itching symptoms could be effectively improved in the 2 experimental groups, and this effect was best in experimental group 2 (Fig. 3).
4 Discussion
UP is one of the most common and uncomfortable symptoms in MHD patients.[28] The current situations of research and treatment in MHD patients with UP have been introduced in the introduction section. The combined treatment of HP and HD is the best blood purification method to remove moderate- and macromolecular weight toxins. The Chinese authoritative guide recommends the combined treatment of HD and HP (HA130-RHA) as a relatively ideal blood purification method to treat UP.[12] Despite all the above, the incidence of UP remains high; and no ideal treatment method is currently available. Curative effect and inflammatory response state between the 2 HP apparatuses (HA330-RHA and HA130-RHA) with different design and absorption characteristics on MHD patients with RUP were compared. These results revealed that in these 2 groups of patients who underwent HP treatment, VAS scores, modified Duo scores, PTH, P3+, [Ca] × [P], and CRP decreased to varying degrees with the extension of treatment. These indexes were better compared with before treatment and the control group (RHD group) (P < 0.05, P < 0.01). After 8 weeks of treatment, VAS scores, modified Duo scores, and CRP were significantly lower in experimental group 2 (HA330-RHA group) than in experimental group 1 (HA130-RHA group, P < 0.05). These revealed that HA330-RHA could safely and effectively improve refractory itching symptoms and the inflammation state in MHD patients. With the extension of treatment, its curative effect became better than that of HA130-RHA. The curative effects on secondary hyperparathyroidism and on calcium and phosphorus metabolism disturbance are similar to these. It is known that HA330-RHA can strongly adsorb inflammatory mediators and endotoxins.[22] Compared with HA130-RHA, its better curative effect may be related to its relative specificity; and it is highly active in the removal of macromolecular-weight inflammation mediators and endotoxins. There are many reports on the application of HA130-RHA in MHD patients with UP.[5,13] The application of HA330-RHA was mainly found in critical patients.[22] There was no report on its application in MHD patients with UP. Although a number of studies have revealed a variety of factors related to the occurrence of UP, no specific pathogeny has been found. It is possible that there may be more complex factors participating in the pathogenesis of RUP. Recent studies[29–33] have revealed that a variety of inflammation factors participate in the pathogenesis of UP. A study[34] has revealed that the complex microenvironment network formed by inflammatory factors and the persistent inflammation state play important roles in the pathogenesis of the repeat attacks of pruritus. A study[35] has suggested that in UP patients, stem cell factors were significantly increased, and the elevation of stem cell factors could recruit chemokines and stimulate mastocyte proliferation and activation. These would induce the release of a variety of inflammatory mediators including histamine, and aggravate skin itching. Some foreign scholars have achieved remarkable curative effects in treating recurrent pruritus using molecular adsorbent recirculating system.[36] This suggested that macromolecular-weight inflammatory mediators may be the key factor of RUP. We consider that there are obviously individual differences in the severity of UP, and current various blood purification methods can alleviate these itching symptoms in some patients. However, its curative effect is limited in some patients. This may be related to the limitations of the scope, efficiency, and amount of the itch causing substances that these blood purification methods can remove. This suggests that UP may be caused by a variety of factors. Its refractory feature may be related to the amount and accumulation of macromolecular-weight inflammatory mediators, and the duration and intensity of the inflammatory state. This study did not further explore the relationship between the scavenging effect of macromolecular-weight inflammatory mediators and its curative effect, which requires further exploration.
Abbreviations: ANOVA = analysis of variance, CRP = C-reactive protein, HD = hemodialysis, HDF = hemodiafiltration, HP = hemoperfusion, β2-MG = β2-microglobulin, MHD = maintenance hemodialysis, PTH = parathyroid hormone, RHA = resin HP apparatus, RHD = regular hemodialysis, RUP = refractory uremic pruritus, UP = uremic pruritus.
Ethic statement: complied ethical standards.
Funding/support: This work was supported by Yanan Hospital Affiliated to Kunming Medical University (yyky014–013).
The authors have no conflicts of interest to disclose.
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PMC005xxxxxx/PMC5371441.txt |
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Medicine (Baltimore)Medicine (Baltimore)MEDIMedicine0025-79741536-5964Wolters Kluwer Health 28328804MD-D-16-0386310.1097/MD.0000000000006180061804500Research ArticleObservational StudyLiver function in alpha-1-antitrypsin deficient individuals at 37 to 40 years of age Mostafavi Behrouz MDaDiaz Sandra MD, PhDbTanash Hanan A. MD, PhDaPiitulainen Eeva MD, PhDa∗Tarantino. Giovanni a Department of Respiratory Medicine and Allergology Malmöb Department of Clinical Radiology Malmö, Skåne University Hospital, Lund University, Sweden.∗ Correspondence: Eeva Piitulainen, Department of Respiratory Medicine and Allergology, Skåne University Hospital, Lund University, Jan Waldenströms gata 24, plan 4, S-205 02 Malmö, Sweden (e-mail: eeva.piitulainen@med.lu.se).3 2017 24 3 2017 96 12 e618031 5 2016 31 1 2017 1 2 2017 Copyright © 2017 the Author(s). Published by Wolters Kluwer Health, Inc.2017This is an open access article distributed under the terms of the Creative Commons Attribution-Non Commercial-No Derivatives License 4.0 (CCBY-NC-ND), where it is permissible to download and share the work provided it is properly cited. The work cannot be changed in any way or used commercially without permission from the journal. http://creativecommons.org/licenses/by-nc-nd/4.0Abstract
Severe alpha-1-antitrypsin (AAT) deficiency (PiZZ) is a risk factor for liver disease, but the prevalence of liver cirrhosis and hepatocellular cancer in PiZZ adults is unknown. The risk of liver disease in adults with moderate AAT deficiency (PiSZ) is also unknown. A cohort of 127 PiZZ, 2 PiZnull, 54 PiSZ, and 1 PiSnull individuals were identified by the Swedish national neonatal AAT screening program between 1972 and 1974, when all 200,000 newborn infants in Sweden were screened for AAT deficiency. The cohort has been followed up since birth. Our aim was to study liver function and signs of liver disease in this cohort at 37 to 40 years of age in comparison with a matched, random sample of control subjects identified from the population registry.
Eighty seven PiZZ, 32 PiSZ, and 92 control subjects (PiMM) answered a questionnaire on medication and alcohol consumption and provided blood samples. Liver stiffness was assessed by Acoustic Radiation Force Impulse (ARFI) elastography in 32 PiZZ, 15 PiSZ, and 51 PiMM subjects.
The median of liver function tests and procollagen-III-peptide were within the normal range in all Pi subgroups. However, the PiZZ men had significantly higher plasma bilirubin than the PiMM men (P = 0.018). Plasma ɣ-glutamyl transferase (GGT) was significantly higher in the PiZZ men (P = 0.009) and the PiSZ men (P = 0.021) compared with the PiMM men. The median of liver stiffness was significantly higher in the PiZZ men (P = 0.037) and the PiSZ men (P = 0.032) compared with the PiMM men. The PiZZ women taking medication influencing liver enzymes had significantly higher GGT than the PiMM women on the corresponding treatment (P = 0.023).
These AAT-deficient individuals identified by neonatal screening have normal plasma levels of liver function tests, and no clinical signs indicating liver disease at the age of 37 to 40 years. However, bilirubin, GGT, and liver stiffness are significantly higher in PiZZ men than PiMM men.
Keywords
alpha-1-antitrypsin deficiencyelastographyliver diseaseliver functionscreeningOPEN-ACCESSTRUE
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1 Introduction
Severe alpha-1-antitrypsin (AAT) deficiency (PiZZ) is a known risk factor for developing liver disease.[1,2] AAT is a 52-kDa protein, a member of the serpin family that inactivates serine proteases such as neutrophil elastase. AAT deficiency is an autosomal codominant hereditary disorder. A mutation in the AAT gene (SERPINA1) leads to the synthesis of defective Z protein with Glu342Lys substitution, which in turn leads to polymerization, accumulation in the endoplasmic reticulum of hepatocytes, impaired secretion, and decreased serum levels.[3–5] The homozygote ZZ genotype may lead to liver cirrhosis and hepatocellular cancer.[6] The defective S protein is not associated with intracellular accumulation of the protein and normally inhibits elastase. The SZ mutation has not been shown to be a risk factor for liver disease in children and the previously published studies in adults are sparse.[6,7] Our gathered knowledge about liver function in AAT deficiency is mostly based on symptoms and disease progression in patients who were first diagnosed with liver affection before they were diagnosed as AAT-deficient. The natural course, early signs, and factors influencing the disease onset are still not clearly understood.
The Swedish national neonatal AAT screening program was carried out between 1972 and 1974, when all 200,000 newborn children were screened for AAT deficiency.[8] The original cohort included 127 PiZZ, 2 PiZnull, 54 PiSZ children, and 1 PiSnull child. The cohort has been followed up regularly.[9–13] Eighteen PiZZ children, but none of the PiSZ children, suffered from liver disease early in life. Five PiZZ children and 1 PiSZ child died before the age of 8 years. On the other hand, 5 new PiZZ individuals born abroad during the screening period have been identified and added to the cohort.
The aim of this study was to investigate liver function and early signs of liver disease at the age of approximately 38 years in this cohort of PiZZ and PiSZ individuals, in comparison with a matched control group randomly selected from the population registry.
2 Methods
2.1 Study population
One PiZZ and 3 PiSZ subjects had died after the previous check-up at the age of 34 years.
All remaining living subjects, 126 PiZZ, 2 PiZnull, 50 PiSZ, and 1 PiSnull individuals, were invited to participate in this follow-up study. A random sample of 300 matched individuals, living in the southern part of Sweden, was identified from the Swedish population registry, and invited to participate as a control group. The control group was the same as that invited at the 2 previous check-ups at 30 and 34 years of age.[12,13]
The study was conducted in accordance with the Helsinki declaration and approved by the Regional Ethical Review Board of Lund, Sweden. All study participants gave their signed, informed consent.
2.2 Questionnaires
A questionnaire was sent to all study participants. It included questions about occupation and occupational exposure, smoking habits, physical activity, general health, symptoms, and medication specified as prescribed by the medical profession, contraceptive medication, over-the-counter medication, and nutritional supplements.
All prescribed medication and contraceptives were checked against information available in Pharmaceutical Specialties in Sweden (www.fass.se). Over-the-counter medication and nutrition supplements were examined on the basis of information available in PUB-Med and internet searches for known liver affection.
To assess alcohol consumption, the study participants answered the Alcohol Use Disorders Identification Test (AUDIT) questionnaire. It consists of 10 questions designed to measure 3 domains: consumption (AUDIT-C, 3 questions on quantity and frequency), dependency (3 questions), and alcohol-related injuries (4 questions about problems or damage caused by alcohol consumption). Each question has a score ranging from 0 to 4. Thus, the maximum score is 40 points. Results above a cut-off of 6 points for women and 8 points for men are indicative of harmful drinking and a score over 20 points strongly indicates dependency. In the AUDIT-C, risk consumption is defined as a score of ≥3 points for women and a score of ≥4 points for men.[14,15]
2.3 Physical examination and blood samples
AAT-deficient individuals visited either their local hospitals or the Department of Respiratory Medicine, Malmö, Sweden. At this consultation, blood samples were analyzed at the local hospitals. The result of the physical examination, diagnoses, medication, and laboratory tests were reported as a study protocol. All control subjects visited the Department of Respiratory Medicine, Malmö.
The following laboratory analyses were performed: plasma aspartate aminotransferase with reference interval for women 0.25 to 0.60 μkat/L and for men 0.25 to 0.75 μkat/L; plasma alanine aminotransferase with reference interval for women 0.15 to 0.75 μkat/lit and for men 0.15 to 1.1 μkat/L; bilirubin with reference interval 5 to 25 μmol/L; plasma alkaline phosphatase (ALP) with reference interval 0.6 to 1.8 μkat/L; plasma gamma glutamyl transpeptidase (GGT) with reference interval for women 0.15 to 0.75 μkat/L and for men 0.15 to 1.9 μkat/L; plasma prothrombin complex (international normalized ratio [INR]) with reference value <1.2; plasma albumin with reference 36 to 48 g/L; platelet count with reference interval for women 165 to 387 × 109/L and for men 145 to 348 × 109/L; and serum procollagen-III-peptide (PIII-NP) with reference interval 0.3 to 0.8 kU/L.[16,17]
2.4 Ultrasound imaging and acoustic radiation force impulse ARFI imaging elastography
ARFI imaging was used to evaluate the mechanical stiffness of liver parenchyma.[18–24] ARFI elastography was performed with a SIEMENS Acuson S2000 ultrasound system (Siemens AG, Erlangen, Germany) with a 4C1 MHz curved array probe. The study subjects had been fasting for at least 3 hours. The examination was performed in the right liver lobe, through the intercostal space. The ARFI measurements were obtained by measuring a numerical value of shear wave velocity (SWV) implemented by Virtual Touch tissue quantification.[23,24] The results are expressed in meters per second (m/s).
2.5 Statistical analysis
Statistical analyses were performed with the Statistical Package for the Social Sciences (SPSS 22.0) software. Because of skewed distribution, the continuous variables were analyzed with nonparametric tests (the Kruskal–Wallis tests and the Mann–Whitney U test). Categorical values were analyzed by the χ2 test. The correlations were examined by Pearson r and in some cases Spearman rho. A P-value < 0.05 was considered significant.
3 Results
3.1 Study participants
Figure 1 shows a schematic representation of the number of individuals in the various investigations. Table 1 presents demographic data of the study participants. The proportion of women was higher in the control group than in the cohort due to a higher participation rate among the female control subjects than among the female AAT-deficient subjects. The median body mass index (BMI) was somewhat higher in the PiSZ group than in the PiZZ and control group (PiMM) but the differences were not statistically significant (Table 1).
Figure 1 Schematic diagram of the participants in the various investigations in the study. The PiZZ group includes 2 PiZnull subjects and the PiSZ group includes 1 PiSnull subject.
Table 1 Demographic data of the study participants and their intake of medication with possible effect on liver function.
3.2 Liver function tests
Due to different reference intervals for men and women regarding some of the liver function tests, the results of the liver function tests were analyzed separately in the male and female Pi subgroups. The results are shown in Table 2 for men and in Table 3 for women. A PiSZ man with a known, advanced stage of alcohol abuse had the highest plasma levels of alanine aminotransferase, aspartate aminotransferase, GGT, and bilirubin (Table 2). When the liver function tests with common reference intervals for both genders were analyzed in men and women together, the median bilirubin level was significantly higher in the PiZZ subjects than in the PiMM subjects (9 μmol/L [range 3–23] vs 7 μmol/L [range 4–33]), P = 0.048. Fifteen (17%) of the PiZZ, 6 (19%) of the PiSZ, and 7 (8%) of the PiMM individuals had at least 1 elevated liver enzyme (P = 0.055).
Table 2 BMI, liver function tests, PIII-NP, and median of stiffness in the right liver lobe measured by AFRI elastography in PiZZ, PiSZ, and PiMM men.
Table 3 BMI, liver function tests, PIII-NP, and median of stiffness in the right liver lobe measured by AFRI elastography in PiZZ, PiSZ, and PiMM women.
3.3 Medication, contraceptives, nutrition supplements, and diagnoses
Seven women were under treatment with levothyroxine substitution (2 PiSZ and 5 PiMM), 5 individuals were under treatment with immunosuppressive treatment (1 PiZZ woman for pelvospondylitis, 1 PiZZ man for ulcerative colitis, 1 PiMM man for rheumatoid arthritis, 1 PiMM man for Mb Crohn, and 1 PiSZ man for juvenile rheumatoid arthritis). Seventy one individuals (24 PiZZ, 38 PiMM, and 9 PiSZ) were being treated with over-the-counter medication, prescribed medication or contraceptives that may affect liver transaminases. In the PiZZ women on medication which potentially affects liver transaminases, the median GGT was 0.52 μkat/L (range 0.3–1.3) as compared to 0.44 μkat/L (range 0.23–1.1) in the PiMM women on the corresponding treatment (P = 0.023). When only contraceptive treatment was included in the analysis, the difference was still significant (P = 0.047).
3.4 Liver stiffness measured by acoustic radiation force impulse (ARFI) elastography
The results of the ARFI elastography in the male and female subgroups are shown in Tables 2 and 3, respectively. The median stiffness in the right liver lobe was significantly higher in the PiZZ men than in the PiSZ men (P = 0.032) and PiMM men (P = 0.037) (Table 2). When the individuals with BMI ≥30 were excluded from the statistical analysis, the difference was significant only between the PiZZ and PiMM men (P = 0.046, see Table 2).
No significant differences in liver stiffness were found between the female Pi subgroups (Table 3).
The results of liver stiffness were stratified into liver disease stages according to the previously published SWV cut-offs, that is, 1.30 m/s for liver fibrosis and 1.80 m/s for liver cirrhosis, see Table 4.[24] No significant differences were found in the proportion of subjects with values indicating liver fibrosis or liver cirrhosis between the Pi subgroups as a whole, nor in the female or male subgroups, see Table 4.
Table 4 Liver stiffness stratified into liver disease stages according to the SWV cut-offs of 1.30 m/s for liver fibrosis and 1.80 m/s for liver cirrhosis in the Pi subgroups.
No significant differences were found in the median values of liver function tests or the use of medication influencing liver function between the subjects with SWV above and those with SWV below the cut-offs for liver fibrosis/cirrhosis. None of the study participants had clinical signs of liver fibrosis or cirrhosis by visual assessment of the liver using ultrasound. Three PiZZ (9%), 3 PiSZ (21%), and 3 PiMM subjects (6%) had increased echogenicity indicating liver steatosis as judged by visual assessment of the liver (ns). There was no relationship between liver steatosis and increased values of SWV. The PiSZ man with known alcohol abuse did not participate in the AFRI elastography examination.
There was a significant correlation between liver stiffness and BMI (P < 0.001) and between liver stiffness and ALP (P < 0.001), see Fig. 2. No significant correlations were found between liver stiffness and the other liver enzymes.
Figure 2 Correlations between liver stiffness and body mass index (BMI) (A), liver stiffness and alkaline phosphatase (B) in 32 PiZZ, 15 PiSZ, and 51 control subjects (PiMM).
3.5 AUDIT questionnaire
The results of the AUDIT scores are shown in Table 5. Because the risk consumption of alcohol differs between men and women, the results of the AUDIT were analyzed separately. The proportion of subjects with risk consumption was higher among the PiZZ men than among the PiMM men. In contrast, the proportion of PiMM women with risk consumption was higher than that of PiZZ women. However, the differences were not statistically significant. No significant correlations were found between alcohol consumption, liver function tests, BMI, or liver stiffness.
Table 5 Results of alcohol consumption (AUDIT-C score) and dependency (AUDIT total score) in men and women divided according to the Pi subgroups.
3.6 Results for PiZZ subjects with neonatal liver disease
Ten of the 18 PiZZ individuals with neonatal liver disease participated in the present follow-up. Five individuals had an AUDIT-score indicating risk consumption; 6 individuals had a BMI indicating slight overweight. All of them had essentially normal liver function test results, see Table 6. Because only 2 women with neonatal liver disease participated in the study, the results are presented for men and women together. No significant differences were found in comparison with PiZZ subjects without neonatal liver disease. None of them had any current diagnosis of liver disease.
Table 6 BMI, liver function tests, and SWV in PiZZ subjects with neonatal liver disease.
3.7 Causes of death in the deceased AAT-deficient subjects
One PiZZ woman died due to acute bacterial meningitis at the age of 36 years. One PiSZ man with known drug and alcohol abuse died at the age of 37 years after a drug overdose. The autopsy in both of these cases revealed a normal liver configuration. Of the other 2 PiSZ cases, 1 woman suffered from liver cirrhosis due to alcohol overconsumption and died secondary to acute hepato-renal syndrome at the age of 37, and 1 woman died at the age of 38 due to acute myocardial inflammation and the autopsy showed an enlarged liver (3050 gr).
4 Discussion
Our results show that at the age of 37 to 40 years, the PiZZ men have significantly higher levels of GGT and bilirubin, and higher liver stiffness assessed by ARFI elastography than the PiMM men. No significant differences in liver function test results and ARFI were found between PiZZ and PiMM women.
GGT is considered to be a sensitive marker for detecting and monitoring liver affection.[25] Contraceptives, some of the prescribed medications, some of the over-the-counter medications, and dietary supplements may cause atoxic elevation of liver transaminases. In the present study, the PiZZ women who were being treated with medication influencing liver enzymes, including oral contraceptives, had higher plasma GGT than the PiMM women with corresponding treatment. Similar results were found at the age of 30, but not at the age of 34.[12,13] However, until the age of 37 to 40, none of the PiZZ women has shown any clinical signs of liver affection. Furthermore, no differences were found in other liver function tests or in ARFI elastography. It remains unclear whether these differences predict future liver disease.
At the 30-year follow-up, significantly higher levels of AST were found in both PiZZ and PiSZ subjects in comparison with the control group.[12] At the 34-year follow-up, the PiZZ individuals had significantly higher mean GGT and albumin than the control group.[13] In both of these previous check-ups, the results of liver function tests were analyzed in men and women together. In the present study, we analyzed the results separately in men and women because of the different reference intervals, and because the gender proportion was not the same among the AAT-deficient and control groups.
PIII-NP is a marker of collagen turnover, and its serum level is considered to be a reliable indicator of hepatic fibrosis in both alcohol and drug-induced liver damage.[26] We did not find any significant differences in PIII-NP between the Pi subgroups (see Tables 2 and 3). Boffa et al[27] have repeated measurements of PIII-NP in patients with psoriasis who were being treated with Methotrexate. They found that a single PIII-NP test could not be considered as a predictor of the development of abnormal histopathology of the liver, but repeated normal levels indicated a low risk of significant liver damage.
In this cohort, PIII-NP has previously only been analyzed at the age of 8, 12, and 16 years. At the age of 12, both PiZZ and PiSZ children had significantly higher PIII-NP than the age matched controls, but at the age of 16, no significant differences were found.[9,10] In adulthood, PIII-NP has not been analyzed in this cohort, and therefore no conclusions can be drawn from our results with normal levels at the present follow-up. It is important to repeat the analysis of PIII-NP at the future follow-ups of the cohort.
ARFI elastography is a new, noninvasive method for detecting and monitoring fibrosis and cirrhosis of the liver.[18,19] We found increased liver stiffness in the PiZZ men in comparison with PiMM men, but no significant differences were found in the female subgroups. Unexpectedly, a high proportion of the study subjects had elevated values of SWV that may indicate liver fibrosis and cirrhosis according to the previously published cut-offs (Table 4).[23] However, the possible presence of liver fibrosis and cirrhosis was similar in all Pi subgroups, both among the men and the women. These results were an isolated finding, because no other clinical or laboratory parameters differed significantly between the subjects with elevated SWV and those with SWV below the cut-off for liver fibrosis/cirrhosis. Furthermore, visual assessment of the liver parenchyma by ultrasound did not reveal any liver disease, and none of the subjects with elevated SWV values shown any signs of liver steatosis. It remains unclear, why we found elevated values of liver stiffness in these asymptomatic, AAT-deficient and healthy control subjects.
Previously published studies have shown good correlations between the result of ARFI measurements and stages of fibrosis determined by biopsy,[21] which is considered to be the most reliable method for assessing hepatic fibrosis and cirrhosis. However, liver biopsy is an invasive procedure with potentially serious complications. In these asymptomatic, AAT-deficient subjects, we did not find that liver biopsy would be ethically justified. This decision was made before the study start, that is, before we had knowledge of the results of elevated liver stiffness in a high proportion of both AAT-deficient and control subjects.
The ARFI result showed a strong correlation with BMI and was also correlated with ALP, but not with other liver function parameters (Fig. 2A, B). To our knowledge, this is the first study in which this method is used to assess liver stiffness in asymptomatic, AAT-deficient individuals.
The PiSZ phenotype is not considered to be a risk factor for liver disease, and none of the PiSZ children in this cohort had clinical signs of liver disease early in life.[8] However, 2 of the 3 PiSZ individuals who had died before the age of 38 years had pathological changes in the liver as seen in the autopsy. They had known alcohol abuse and both had liver cirrhosis, and 1 was on the waiting list for liver transplantation. Whether the liver pathology was caused only by alcohol or whether these individuals are more vulnerable to alcohol than the general population remains unclear. At the present check-up, 1 PiSZ man had an advanced stage of alcohol abuse. He also had elevated liver function tests. Nevertheless, except for a significantly higher GGT in PiSZ men compared with the PiMM men, no other significant differences were found in liver function tests or AFRI elastography between the PiSZ and PiMM subjects.
Only 1 PiZZ woman has died after the age of 8 years. She was 36 years of age, and the cause of death was acute meningitis. All remaining PiZZ individuals are alive, and none of those participating in the present follow-up suffered from liver disease. Their liver function tests were essentially within the normal range (Tables 2 and 3). Also the PiZZ subjects who suffered from liver disease early in life had normal liver function test results (Table 6). Thus, our results show that the prognosis of liver function in the PiZZ individuals identified by neonatal screening seems to be good up to 37 to 40 years of age.
There are some limitations in our study. Due to long distances or their social situation, not all AAT-deficient subjects were able to visit Malmö. A common reason for not participating was well-being. Despite the fact that many of them visited their local hospitals where the liver function tests were analyzed, the participation rate was relatively low, which may have influenced the results. The ARFI elastography was performed in the afternoon, and thus the subjects were not in correct fasting condition, only having fasted for a minimum of 3 hours. The diagnoses were self-reported, and therefore we cannot exclude that some subjects had undiagnosed liver disease.
In conclusion, at the age of 37 to 40 years the PiZZ and PiSZ individuals identified by neonatal screening have normal plasma levels of liver function tests and PIII-NP. However, bilirubin, GGT, and liver stiffness, as assessed by AFRI elastography, differ significantly between the PiZZ and the PiMM men.
Acknowledgments
The authors thank Ewa Ringdal Szemberg, Isabella Björk and Helene Johansson Kvist for technical and secretarial support. The authors also thank all Swedish colleges for reporting data; and Tomas Sveger and Olle Ekberg for their contribution and constructive criticism.
Abbreviations: AAT = alpha-1-antitrypsin, ALP = alkaline phosphatase, ARFI = acoustic radiation force impulse, AUDIT = Alcohol Use Disorders Identification Test, BMI = body mass index, GGT = gamma glutamyl transferase, Pi = protease inhibitor, PIII-NP = procollagen-III-peptide, SWV = shear wave velocity.
Funding/support: This study was supported by Swedish Heart-Lung Foundation, Skåne University Hospital Grant.
The authors have no conflicts of interest to disclose.
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Medicine (Baltimore)Medicine (Baltimore)MEDIMedicine0025-79741536-5964Wolters Kluwer Health 28328805MD-D-16-0448310.1097/MD.0000000000006189061894400Research ArticleDiagnostic Accuracy StudyIdentifying multiple myeloma patients using data from the French health insurance databases Validation using a cancer registryPalmaro Aurore PhDabc∗Gauthier Martin MScdConte Cécile MScabGrosclaude Pascale MD, PhDbefDespas Fabien PharmD, PhDabcLapeyre-Mestre Maryse MD, PhDabcHsu. Ching-Sheng a Medical and Clinical Pharmacology Unit, Toulouse University Hospitalb INSERM 1027, University of Toulousec CIC 1436, Toulouse University Hospitald Department of Hematology, Toulouse University Hospitale Tarn Cancer Registry, Albif French Network of Cancer Registries (FRANCIM), France.∗ Correspondence: Aurore Palmaro, Medical and Clinical Pharmacology Unit, Toulouse University Hospital, Pharmacoepidemiology Research Unit, INSERM 1027, University of Toulouse, 37, allées Jules Guesde, 31000 Toulouse, France (e-mail: aurore.palmaro@univ-tlse3.fr).3 2017 24 3 2017 96 12 e61894 7 2016 16 12 2016 3 2 2017 Copyright © 2017 the Author(s). Published by Wolters Kluwer Health, Inc.2017This is an open access article distributed under the terms of the Creative Commons Attribution-Non Commercial License 4.0 (CCBY-NC), where it is permissible to download, share, remix, transform, and buildup the work provided it is properly cited. The work cannot be used commercially without permission from the journal. http://creativecommons.org/licenses/by-nc/4.0Supplemental Digital Content is available in the text
Abstract
This study aimed to assess the performance of several algorithms based on hospital diagnoses and the long-term diseases scheme to identify multiple myeloma patients.
Potential multiple myeloma patients in 2010 to 2013 were identified using the presence of hospital records with at least 1 main diagnosis code for multiple myeloma (ICD-10 “C90”). Alternative algorithms also considered related and associated diagnoses, combination with long-term conditions, or at least 2 diagnoses. Incident patients were those with no previous “C90” codes in the past 24 or 12 months. The sensitivity, specificity, and positive and negative predictive values (PPVs and NPVs) were computed, using a French cancer registry for the corresponding area and period as the criterion standard.
Long-term conditions data extracted concerned 11,559 patients (21,846 for hospital data). The registry contained 125 cases of multiple myeloma. Sensitivity was 70% when using only main hospital diagnoses (specificity 100%, PPV 79%), 76% when also considering related diagnoses (specificity 100%, PPV 74%), and 90% with associated diagnoses included (100% specificity, 64% PPV).
In relation with their good performance, selected algorithms can be used to study the benefit and risk of drugs in treated multiple myeloma patients.
Keywords
algorithmscancer registryelectronic health recordsmultiple myelomapharmacoepidemiologysensitivity and specificityOPEN-ACCESSTRUE
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1 Introduction
Multiple myeloma (MM) is the second most common hematological malignancy in France. [1,2] In the last 2 decades, transplantation approaches and new drug regimens based on immunomodulatory drugs or proteasome inhibitors have considerably improved the survival of these patients.[3] These patients are now essentially treated as outpatients. Hospital-based observational studies are then no more sufficient to study real-life practices and patients’ outcomes (adherence, among others.).
In parallel, researchers have access to the large French health insurance databases, covering >98% of the French population. French health insurance databases are potentially a valuable source for studying multiple myeloma epidemiology, healthcare use, and clinical outcomes, as it is among the rare automated databases in which certain hospital-administered medications are identifiable on an individual level. Indeed, the SNIIRAM (“Système national d’information inter-régime de l’assurance maladie”) gathers ambulatory and hospital data. Its potential for research is also in relation with its national coverage and the availability of details on long-term conditions.
To implement epidemiological or pharmacoepidemiological studies on these patients, the validity of the coding is of primary importance.[4–6] As algorithms’ performance could be in many ways database-specific, there was a need to implement this validation study in French health insurance databases. A lot of previous validations were made with the ICD-9 in databases in the United States and validation studies are lacking for European and Nordic databases, in which ICD-10 is more frequent.[6] Although several studies have measured the validity of cancer cases ascertainment in France,[7–9] none focused on hematological diseases. Then, the validity of identification of multiple myeloma cases through these databases has not been previously established. This study aimed to assess the performance of several algorithms based on hospital diagnoses (PMSI, “Programme de médicalisation des systèmes d’ information”) and diagnoses from the long-term diseases (LTDs) scheme.
2 Material and methods
2.1 Setting and design
We conducted a population-based and retrospective validation study of MM case ascertainment through health insurance records, using the Tarn cancer registry as the reference standard. For the Tarn Cancer registry, the period of interest was 2010 to 2013 (all incident cases diagnosed during 2010–2013). In health insurance records, date of diagnosis is not available, and an “observation period” (12 or 24 months here) without any diagnosis of interest is required to discriminate incident (“new”) from prevalent patients. When no diagnosis of interest is recorded for up to 12 or 24 months, and then a first diagnosis occurs after this period, the patient is considered as incident. Then, for hospital diagnoses and long-term conditions, a longer extraction period has to be used (2008–2013) to enable at least 24 months (2008–2010) or 12 months (2009–2010) of observation (and use of the first occurrence of MM diagnosis after this period as a proxy of diagnosis date).
2.2 The Tarn Cancer registry
The Tarn Cancer Registry collects cancer data related to inhabitants of the Tarn area (about 400,000), an administrative area located in the southwest of France. Case ascertainment in the registry is based on systematic data collection from different sources: long-term diseases according to the health insurance schemes, hospital data for all residents of the Tarn area (all hospital data for the Tarn, plus data from hospital and reference centers in surrounding regions outside Tarn area), oncology regional network, pathology laboratories, hematology and cytology laboratories, all relevant hospital departments in public hospital or private clinics, radiotherapy centers, office from specialized physicians, and electoral registers.[10] Diagnoses are coded according to the International Classification of Diseases for Oncology, 3rd Edition (ICD-O-3).[11] The registry contains demographic details and some clinical or testing results. It also includes date of diagnosis attributed according international guidelines.[12]
Data from the registry were obtained for patients with hematological malignancies (ICD-O-3 topography code C42). Confirmed cases of multiple myeloma were patients diagnosed in 2010 to 2013 with ICD-O code “9732/3” for multiple myeloma, “9731/3” (for plasmacytoma), and “9734/3” (extramedullary plasmacytoma) in the registry. Clinical data were extracted for descriptive purposes.
2.3 Data from hospitalization stays PMSI
Data from hospitalization stays (PMSI) for the corresponding area and period (2010–2013 plus 2008–2009 or 2009 only for the observation period) were also obtained. Hospital data are managed within a single case-mix database of the activity-based payment system, (“tarification à l’activité,” T2A). Data provided came from medical, surgical, and obstetrics care (PMSI MCO). PMSI provides data on all claims paid by the national health insurance system (covering >98% of the French population[13]) to public and private hospitals. Main, related, and associated diagnosis codes are coded according to the 10th version of the international classification of the diseases (ICD-10).[13] The data extraction was realized for hospital episodes involving a main diagnosis for cancer (ICD-10 “C” or “D”) or chemotherapy (“Z51”).
2.4 Diagnoses from “long-term conditions” scheme
Data from long-term conditions (LTDs) (affections de longue durée - ALD) for all patients with cancer (ICD-10 “C” or “D”) were extracted for the period 2008 to 2013, to enable at least 24 months (2008–2010) or 12 months (2009–2010) for the observation period. LTD provision is dedicated to patients suffering from a chronic condition which requires long-term treatment or expensive drugs. Healthcare expenses in relation to these conditions are fully covered. The list is established by decree (30 conditions), and include for instance malignant tumors, diabetes, or long-term psychiatric conditions. Diseases are coded according to ICD-10.[13] Entry in the LTD is obtained following a request by a physician (often the general practitioner) and is not systematically requested, in particular when the patient is already in the scheme for another disease. However, it is a common practice for researchers working on French healthcare databases to use LTD in combination with hospital diagnoses to improve sensitivity of disease identification or to measure comorbidities (Charlson score, among others).[13]
2.5 Data collected
Data from both data sources were obtained as nonanonymized data. Linkage between both sources was done on the basis of combinations of 5 potential matching variables: family name, birth name, first name, date of birth, sex, place of birth (“commune,” lowest administrative area in France). Twenty-four possible combinations were tested. Unmatched patients were considered as having no hospital or LTD records during the period.
Nonanonymized hospital and LTD data have the same origin and structure as those contained in the national and anonymized health insurance database widely used for research (SNIIRAM). Combining hospital and LTD data at the local level is intended to simulate the performance of further algorithms that would be based on the SNIIRAM only.
2.6 Confidentiality and ethics
Data from hospitalization stays and long-term conditions were only those previously extracted for internal use of the Tarn Cancer Registry. All data were treated confidentially. The Tarn Cancer Registry is registered at the CNIL, French national data privacy institute (99 80 15 [12/1998], 99 80 15 version 2 [10/2003]).
2.7 Statistical analyses
Descriptive statistics were used to characterize the study population. Potential multiple myeloma patients in 2010 to 2013 were identified in the French health insurance databases using hospital records (PMSI) or LTD data. Indeed, the algorithm should use hospital data, but diagnoses are organized into 3 categories of diagnosis, and impacted by coding practices (main and related diagnoses are diagnoses of the current hospitalization, whereas associated diagnosis could be related to older episodes). When designing an algorithm, we have to include either main, main + related, or all types of diagnosis. As we did not have strong a priori on how these combinations will perform, we decided to test it systematically, for the 2 observation periods and with and without LTD to identify the combination providing the best performance. The algorithms tested began with a very straightforward approach (at least 1 main diagnosis), and then tested additional combinations and then cumulative diagnosis. Owing to the organization of the LTD scheme (long periods of coverage with start and end date), searching cumulative records was not relevant for this source.
In total, 13 algorithms corresponding to 3 strategies were tested with 2 different durations for defining incident patients (option A: 24-month observation period; option B: 12 months): Strategy 1, algorithms based on hospital data only (either main, main + related, or main + related + associated diagnoses), Strategy 2, algorithms based on hospital data or long-term condition (at least 1 long-term condition or either main, main + related, or main + related + associated diagnoses); and Strategy 3, cumulative diagnosis conditions for hospital data only (a 2nd MM main, main + related, or main + related + associated diagnosis, ≥30 days after the 1st). This cumulative condition was introduced with a temporal condition, as diagnoses belonging to the same episode (including transfers) are likely to be affected by the same potential coding error. True-positive patients were those ascertained as multiple myeloma cases in the registry (ICD-O code “9732/3,” “9731/3,” or “9734/3” in 2010–2013), and correctly identified as MM cases when applying the algorithm to health insurance data. True negative were those with no ICD-O code for MM in the registry, and not identified as MM cases according to the algorithm. False-positives were those not registered as MM cases in the registry (no corresponding ICD-O codes), but incorrectly identified as MM cases when using the algorithm based on health insurance data. False-negative were those ascertained as MM cases in the registry, but not identified as MM cases according to the algorithm. The sensitivity, specificity, positive predictive values (PPVs), and negative predictive values (PPVs) of the algorithms were then computed, using the cancer registry as the criterion standard. Exact binomial 95% confidence intervals were computed for each parameter. Youden index (sensitivity + specificity − 1) was computed as an indicator of model performance. Receiver-operating characteristic curves are provided as supplementary content. Considering further use in pharmacoepidemiological research, specificity was prioritized over sensitivity to reduce the potential impact of misclassification on risk estimates.[14] Statistical analyses were performed using SAS 9.4 (SAS Institute Inc, Cary, NC). Method of validation was reported in accordance with the modified Standards for Reporting of Diagnostic Accuracy criteria.[15,16] Concordance between date of diagnosis in the registry and first “C90”multiple myeloma code in LTD or hospital database was assessed using median time between date of diagnosis in the registry and first multiple myeloma “C90” code in number of days.
3 Results
3.1 Patients
For the period 2010 to 2013, the registry contained 125 incident cases of multiple myeloma (including 7 cases coded as plasmacytoma). According to the characteristics presented Table 1, median age was 74 (interquartile range, 63–81) and 57% were male (n = 71). Half of the patients were classified as stage III or IIIa according to the Durie-Salmon system.
Table 1 Characteristics of multiple myeloma patients in the Tarn cancer registry (N = 125).
Long-term conditions data recorded for the corresponding area concerned 11,559 patients for the period 2008 to 2013. Hospital data were available for 21,846 inhabitants of the Tarn area (2008–2013). Data from the registry were obtained for 1069 patients. Computations were then made on the joint population of both data sources, (i.e., 22,083), as 1 patient could be in >1 data source). Among the 125 MM patients in the registry, 115 (92%) had at least 1 matching record in hospital data, and 68 (54%) had at least one match with LTD records.
Sensitivity, specificity, and predictive values are reported in Table 2 (option A: 24-month observation period without diagnosis to select incident patients) and Table 3 (option B: 12-month observation).
Table 2 Algorithms performance when using hospitalization or long-term conditions (option A: 24-month observation period∗).
Table 3 Algorithms performance when using hospitalization or long-term conditions (option B: 12-month observation period∗).
3.2 Algorithms performance using both data sources separately (strategy 1)
From 2010 to 2013, 112 patients were identified as incident cases using main diagnoses from PMSI data (128 when using main and related diagnoses, and 177 with associated diagnoses) when using a 24-month observation period (option A, Table 2). Sensitivity was 70.4% (62.4%–78.4%) when using only main hospital diagnoses (specificity 99.9%, PPV 78.6%), 76.0% (68.5%–83.5%) when considering also related diagnoses (specificity 99.9%, PPV 74.2%), and 90.4% (85.2%–95.6%) with associated diagnoses included (99.7% specificity, 63.8% PPV).
Using a 12-month observation period (option B, Table 3) gave very close results, with similar sensitivity (90.4%) and slight differences visible for the PPV (59.5% vs. 63.8%), but with overlapping confidence intervals.
3.3 Impact of long-term conditions (strategy 2)
LTD alone exhibited very poor performance, with sensitivity around 55% whatever the period of observation used. In the algorithm considering a 24-month period to define incident cases (option A, Table 2), sensitivity was increased by up to 10% when incorporating long-term conditions to main hospital diagnoses. However, the interest of long-term conditions was attenuated after integrating associated diagnoses (+6%), and disappeared in all algorithms integrating associated diagnoses (same value for sensitivity for algorithm with main, related or associated code [90%], with or without LTD, 12 or 24 months’ period).
Using a 12-month observation period did not impact the performance of the algorithm (option B, Table 3).
3.4 Impact of the number of diagnoses required (strategy 3)
When a second diagnosis was required >30 days after a first diagnosis (24-month observation period; option A, Table 2), sensitivity dropped dramatically to very low values (19%). Impact of specificity was not observable as it was already maximal (99%) for the algorithm with only one diagnosis required. Among the 88 true-positive patients identified using the first algorithm (at least 1 main hospital diagnosis, 24-month period), 62% (55/88) have only 1 hospital diagnosis and 38% (33/88) ≥1 main hospital diagnoses.
The performance of this strategy for a 12-month observation period (option B, Table 3) was similar.
3.5 Impact of period of observation (24 vs. 12-month observation period)
There was no decrease in sensitivity and very slight reductions in PPV (<3%) as the observation window increased from 12 to 24 months (Table 3 vs. Table 2). Varying the window between MM codes and exclusion criteria did not improve algorithm performance. The algorithm using a 12-month observation period (option B) and “at least 1 main, OR related, OR associated hospital MM code” (strategy 1) exhibited the same highest performance (Youden's index: 90.1) as compared to the same algorithm with a 24-month period (Tables 2 and 3).
3.6 Exploration of diagnoses in false incidents
Using the first algorithm (at least 1 main diagnosis, option A: 24 months), 24 patients were classified as false-positive cases (patients misclassified as having MM). Among these false-positives, 2 were identified in the registry, with ICD-O-3 diagnoses of plasmablastic lymphoma (“9735/3”) and refractory thrombocytopenia (“9992/3”). All other false-positive patients were patients with hospital data, but not retrieved in the registry. When looking at their other hospital diagnoses, no other code for distinct hematological malignancies was retrieved. Two patients had diagnoses for bone metastasis (ICD-10 “C79”).
For the false-negative patients for algorithms using only main diagnoses (respectively, main or related), all appeared to be incident MM cases that would be selected when using either or related or associated hospital code (respectively, associated codes). Finally, almost all false-negatives had no available hospital records, and only 1 ascertained MM case had another hospital diagnosis (D46.2: refractory anemia with excess of blasts).
3.7 Exploration of delays between first hospital record and date of diagnosis in the registry
When considering time between diagnosis in the registry and date of first MM diagnosis in hospital data (Table 4), correspondence was high, with a median time of 0 days (interquartile range -2; 21 for main, related or associated diagnoses and a 24-month period), and 94% (83/88) of patients with a main diagnosis between 30 days before and within 1 year after registry documented MM diagnosis (72% between 30 days before and 30 days after, 63/88).
Table 4 Concordance between date of diagnosis in the registry and first multiple myeloma “C90” code in healthcare database.
4 Discussion
4.1 Main findings
Algorithms tested exhibited very different performances, ranging from poor performance when using only main hospital diagnoses to very acceptable parameters when hospital data are used in combination with long-term conditions diagnoses. The optimal algorithm to identify MM patients (maximizing both Youden index and specificity) was “at least 1 main, OR related, OR associated hospital MM code,” with a 12-month observation period, which had a sensitivity of 90%, a specificity of 100%, and a PPV of 60%. The same algorithm with a 24-month observation period demonstrated similar performance, but the algorithm with the shorter period of observation should be preferred. In the same way, one of the algorithms for strategy 2 performed equally well (“at least 1 MM main, related or associated hospital MM code) OR at least 1 LTD MM code”), but would require to have LTD data available. Faced to these 2 algorithms with equal performances, we choose the one requiring the minimum data (i.e., with no participation of data from the LTD scheme).
Indeed, the study design simulated the performance of algorithms that would be based on the large French health insurance databases (SNIIRAM) in further research. Using an algorithm with a restricted period of observation (12 months as compared to 24 months) has potentially a great interest for increasing sample size and length of possible follow-up in the context of limited longitudinal data availability (data are available since 2006 in the SNIIRAM).
4.2 Strengths and limitations
Some limitations must be acknowledged. First, this study was conducted in a single area and may not perfectly reflect the performance of hospital and LTD codes at the national level. However, coding is quite similar in all private and public hospitals. However, several data suggest that clinical and coding practices in Tarn region are very close to that of the whole nation. According to national estimations, 51% of newly diagnosed MM (or proliferative disorders) were male, with 70% aged >65 years. [1] In our study, 58% were male and 67% were older than 65 years. Sex and gender characteristics are then quite close to the national reference. Clinical features of the patients are not expected to be different in France, but might be acknowledged at the larger scale (i.e., at the European level) owing to different delay to diagnosis. As we only used specific MM codes and not symptoms, the performance of our algorithm is not likely to be affected by the clinical aspect. Concerning coding practices for health insurance data, there are national standards of coding PMSI data, for the choice of the principal diagnosis for instance. Of course, we could not rule out various coding habits between hospitals or regions because of different interpretation of coding rules. This study is then conducted with the assumption of similar coding practices in all hospitals. However, in practice, quality of coding is regularly audited in public and private hospitals for reimbursement purposes.
Another potential limitation is related to the assumption that all patients with available data from the registry corresponding area and period should be considered as potential cases. In other words, failure of linkage with administrative data meant that the patient had no LTD or hospital record for the period of interest. However, even if there is systematic attempt to obtain cancer hospital data from all inhabitants of the covered area (Tarn), including hospitals outside the area of the residence, there is a possibility that hospital episodes were not complete, leading to underestimate the performance of the algorithm (increase in false-negative). Differences were observed when matching records from the cancer registry and the 2 data sources (21,846 for hospital data vs. 11,559 for LTD). These variations were expected. Indeed, although coding of hospital episodes will be always performed, LTD status is not automatically assigned to a patient and has to be requested by a physician. Then, the greater number of hospital records compared to LTD records should not be interpreted as missing information, but simply reflect the organization of the healthcare system.
In addition, the relative lack of sensitivity of the algorithm was expected owing to the particular natural history of multiple myeloma. Indeed, patients are not systematically managed in hospital, nor treated after diagnosis, because of possible asymptomatic or smoldering disease. Those patients are less likely to go to hospital or to enter in a long-term condition scheme. Lack of sensitivity for identifying these patients could be problematic for epidemiological purposes, but is acceptable for healthcare use or pharmacoepidemiological research, as these patients are not healthcare users.
In this study, we focused on the need to accurately identify myeloma patients (specificity), which would undergo additional selection criteria to be included in pharmacoepidemiological study for instance. Algorithms integrating treated patients would certainly have been more sensitive[17], but we did not have sufficient information in the registry to ascertain this. Finally, lack of sensitivity is likely to be controlled in additional selection process, and the high specificity of the algorithm is an important strength here.
The false-positives for non-MM patients having at least 1 MM diagnosis code may be related to testing for disease rather than confirmed disease or to coding errors, or perhaps may be because of the evolution of diagnoses over time. There would be a potential interest to require not only one but several diagnosis codes (“cumulative diagnoses” strategy) to overcome this issue. Then, as expected, the increase in the number of diagnosis codes further improved specificity, but sensitivity reached unacceptable levels (<60%). In practice, MM patients may not be hospitalized several times after initial diagnosis (62% of confirmed MM cases has only 1 hospital diagnosis in our study), thus limiting the relevance of algorithms requiring multiple diagnosis codes.
Another consideration in relation to hematological malignancies is the possibility of lack of recording in the registry, as shown for myeloid malignancy in the United States.[18,19]
4.3 Other French experiences
Data from the French health insurance database have already been used for epidemiological identification of cancer,[20] including for instance breast,[21] colorectal,[9] prostate,[22] thyroid,[7] or central nervous system malignancies.[8] A work has also been implemented in French hospital data to select cancer related hospitalization, and myeloma was listed among the diseases of interest.[23]
4.4 International experiences
Validation of case identification algorithms represents an important issue, as demonstrated by recent calls,[6] and also by several initiatives from Mini Sentinel and OMOP (Observational Medical Outcomes Partnership) in United States or EU-ADR in Europe.[24] An important series of systematic review on methods for validating a wide range of disease, including lymphoma for instance,[25] has been published since 2012.[26–32] Lessons learned and proposal for improvement have been formulated during these validation studies.[33] However, literature concerning multiple myeloma is very poor, and only one resource could be identified.[34] According to this study, on MarketScan databases linked to Medicare claims databases, at least 2 diagnoses provided a sensitivity of 95%, a specificity of 73%, and a positive predictive value (PPV) of 76%.
5 Conclusions
This study revealed that including simultaneously main, related, and associated hospital diagnoses increased the sensitivity of the algorithm without generating excess false positives. The optimal algorithm to identify MM patients was “at least 1 main, OR related, OR associated hospital MM code,” with a 12-month observation period, which had a sensitivity of 90%, a specificity of 100%, and a PPV of 60%. This algorithm can be used in further pharmacoepidemiological studies for investigating the benefits and risks of drugs used by multiple myeloma patients.
Supplementary Material
Supplemental Digital Content
Abbreviations: CI = confidence interval, dx = diagnosis, ICD-9/10 = International Classification of Diseases, 9th/10th version, ICD-O-3 = International Classification of Diseases for Oncology, 3rd Edition, IQR = interquartile range, LTD = long-term condition scheme, MM = multiple myeloma, OMOP = observational medical outcomes partnership, PMSI = Programme de médicalisation des systèmes d’ information (Program for the Medicalization of Information Systems), NPV = negative predictive value, PPV = positive predictive value, SNIIRAM = Système national d’information inter-régime de l’assurance maladie (National inter-scheme information system on health insurance), T2A = tarification à l’activité (activity-based diagnosis Related Groups payment system).
This work has been supported by the National Research Agency (ANR: Agence Nationale de la Recherche) for the “investissement d’avenir” (ANR-11-PHUC-001, CAPTOR project) and by “La ligue contre le Cancer.”
The authors declare no conflict of interest.
Supplemental Digital Content is available for this article.
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Medicine (Baltimore)Medicine (Baltimore)MEDIMedicine0025-79741536-5964Wolters Kluwer Health 28328808MD-D-16-0567810.1097/MD.0000000000006297062976800Research ArticleDiagnostic Accuracy StudyVertebrobasilar system computed tomographic angiography in central vertigo Paşaoğlu Lale MD, Radiologyst∗Tusconi. Massimo Ankara Numune Training and Research Hospital, Altindag, Ankara, Turkey.∗ Correspondence: Lale Paşaoğlu, Ankara Numune Training and Research Hospital, Hacettepe Mahallesi Talatpasa Bulvari, No. 44, Altindag, Ankara, Turkey (e-mail: ldamgaci@hotmail.com).3 2017 24 3 2017 96 12 e629715 9 2016 2 2 2017 14 2 2017 Copyright © 2017 the Author(s). Published by Wolters Kluwer Health, Inc.2017This is an open access article distributed under the terms of the Creative Commons Attribution-Non Commercial License 4.0 (CCBY-NC), where it is permissible to download, share, remix, transform, and buildup the work provided it is properly cited. The work cannot be used commercially without permission from the journal. http://creativecommons.org/licenses/by-nc/4.0Abstract
The incidence of vertigo in the population is 20% to 30% and one-fourth of the cases are related to central causes. The aim of this study was to evaluate computed tomography angiography (CTA) findings of the vertebrobasilar system in central vertigo without stroke.
CTA and magnetic resonance images of patients with vertigo were retrospectively evaluated. One hundred twenty-nine patients suspected of having central vertigo according to history, physical examination, and otological and neurological tests without signs of infarction on diffusion-weighted magnetic resonance imaging were included in the study. The control group included 120 patients with similar vascular disease risk factors but without vertigo. Vertebral and basilar artery diameters, hypoplasias, exit-site variations of vertebral artery, vertebrobasilar tortuosity, and stenosis of ≥50% detected on CTA were recorded for all patients. Independent-samples t test was used in variables with normal distribution, and Mann–Whitney U test in non-normal distribution. The difference of categorical variable distribution according to groups was analyzed with χ2 and/or Fisher exact test.
Vertebral artery hypoplasia and ≥50% stenosis were seen more often in the vertigo group (P = 0.000, <0.001). Overall 78 (60.5%) vertigo patients had ≥50% stenosis, 54 (69.2%) had stenosis at V1 segment, 9 (11.5%) at V2 segment, 2 (2.5%) at V3 segment, and 13 (16.6%) at V4 segment. Both vertigo and control groups had similar basilar artery hypoplasia and ≥50% stenosis rates (P = 0.800, >0.05).
CTA may be helpful to clarify the association between abnormal CTA findings of vertebral arteries and central vertigo.
This article reveals the opportunity to diagnose posterior circulation abnormalities causing central vertigo with a feasible method such as CTA.
Keywords
basilar arteryCTAvertebral arteryvertigoOPEN-ACCESSTRUE
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1 Introduction
The incidence of vertigo in the population is 20% to 30%.[1] While otological, central, somatosensorial, and visual factors may cause vertigo, central causes are responsible in one-quarter of the cases.[2] Semicircular canals, saccule, utricle, and the vestibular nerve create the peripheral vestibular system. Vestibular nucleus, cerebellum, cerebral peduncle, the spinal cord, and vestibular cortex create the central vestibular system.[3] Central vertigo may be accompanied by neurological symptoms such as ataxia, dysarthria, diplopia, and visual disturbance or weakness.[4] Central vertigo can be distinguished from peripheral vertigo through history, neurological examination, and imaging findings.[3] Most common causes of central vertigo are vertebrobasilar insufficiency, stroke, transient ischemic attack (TIA), migraine, multiple sclerosis, posterior fossa tumors, neurodegenerative disorders, some drugs, and psychiatric conditions.[3,4]
Central vertigo related to cerebellar and cerebral peduncle strokes was presented in many studies with magnetic resonance imaging (MRI).[5–9] However, there are no computed tomography angiography (CTA) studies investigating vertebrobasilar artery changes in central vertigo patients without stroke. Both CTA and contrast-enhanced magnetic resonance angiography (MRA) have high sensitivity and specificity for detecting ≥50% stenosis of vertebral artery.[10–13]
The aim of this study was to investigate the vertebrobasilar system CTA findings of central vertigo without stroke.
2 Methods
Local ethics committee approval was obtained (approval number: 2014/906).
2.1 Patient selection
Between January 2010 and January 2014 patients who had undergone CTA and MRI were retrospectively evaluated on picture archiving and communication system (PACS). Clinical data, vascular risk factors, physical examination findings, and radiological images were evaluated. The duration, intensity, and frequency of vertigo and accompanying symptoms were asked. According to the neurological examinations, horizontal, vertical, or rotational nystagmus did not decrease when the patients with abnormal skew tests focused their gaze and these patients were considered to have central vertigo. One hundred sixty-three patients with abnormal skew tests were considered to have central vertigo and included in the study.
CTA images of all patients were evaluated on PACS by an experienced radiologist. Of these 163 cases, 25 patients with central vertigo were excluded from the study because of lacking diffusion-weighted MRI (DWI). Nine patients with cerebellar or cerebral peduncle infarction detected on DWI were also excluded from the study. DWI was evaluated on PACS by the same radiologist. A total of 129 (51.8%) patients with central vertigo and 120 (48.2%) controls with similar age and vascular risk factors (diabetes, hypertension, and dyslipidemia) were included in the study. Control patients selected from the PACS had CTA examinations done for headache and evaluation of carotid and vertebral artery stenosis without vertigo.
2.2 Computed tomography angiography
CTA scans were performed with a 64-detector (Aquilion 64, Toshiba Medical Systems, Tochigi, Japan, 2011) or a 16-detector (Aquilion 16, Toshiba Medical Systems, 2005) computed tomography (CT) device. Scanning parameters of the 64-detector CT were as follows: collimation 64 × 0.5, gantry rotation time 0.5 second, slice thickness 0.5 mm, step value 0.64, 120 kV, and 450 mA. Scanning parameters of the 16-detector CT were as follows: collimation 16 × 1.0, gantry rotation time 0.75 second, slice thickness 1 mm, step value 0.75, 120 kV, and 300 mA.
Patients were placed in supine position and their heads immobilized with cranial coil and immobilization devices. Caudocranial scans were performed after the localization was determined on lateral topogram; the patients were told not to swallow and to breathe shallowly.
Nonionic, high-iodine concentrated, 100-mL, intravenous (350–400 mg/mL iodine concentration) contrast material was delivered from the antecubital region via 18- to 20-gauge cannula with an automated pump at 4 mL/s (Ulrich Medizin version, 2004, Germany). After the contrast material, 40 cm3 of normal saline was administered.
CTA imaging was performed with bolus tracking method, and the scanning started after the density of the aortic arch reached 120 to 130 Hounsfield units. The total duration of scanning with the 64-detector CT was 8.6 seconds, and with the 16-detector CT 9.7 seconds.
2.3 CTA assessment
The images obtained on CTA were evaluated using Vitrea (4.14.4, 2008, Vital Images Inc, Minnetonka, MN) or Aquarius (iNtuition edition version 4.4.11.82.6784, TeraRecon Inc, Foster, CA) software in axial, sagittal, coronal, or oblique planes, and using multiplanar reconstruction, volume rendered, and maximum-intensity projection images. HP ZR2440W (24 in., 1920 × 1200 at 60 Hz) and ASUS PB278Q (27 in., 2560 × 1440 at 60 Hz) monitors were used in the evaluation of the images.
The origins of the vertebral arteries were evaluated and the vertebral and basilar arteries were inspected along their trace on the axial images. Vertebral artery diameters on the V2 segment at the C4 vertebrae levels were measured with 200% magnification between outer contours on coronal reformatted images. In patients with atheromatous plaques the vessel diameter was measured distally from the plaque on places without plaque. Vertebral arteries were classified as normal, hypoplastic, and ≥50 stenotic (Fig. 1). Diameters <2 mm and the posterior inferior cerebellar artery ending termination of the vertebral arteries were accepted as hypoplastic (Fig. 2). Vertebral artery segments were classified as follows: V1, from origin to the transverse foramina of C5 or C6 vertebrae; V2, from the transverse foramina of C5 or C6 to the transverse foramina to C2; V3, from the C2 transverse foramina to dura; and V4, from dura to the confluence of 2 vertebral arteries to form the basilar artery (Fig. 3A and B). Basilar artery diameter was measured from coronal reformatted images at midline pontine level with 200% magnification between outer contours. Basilar artery was classified as normal, hypoplastic, and ≥50% stenotic. Diameters <2 mm were accepted as hypoplastic (Fig. 4A and B). Curving, angulation/kinking, looping, and spiral twisting vertebral arteries were regarded tortuous (Fig. 5). If the basilar artery, throughout its course, lay lateral to the margin of the clivus or dorsum sellae or if the artery bifurcates above the plane of the suprasellar cistern, it was regarded as tortuous.
Figure 1 A 72-year-old-man with vertigo. A 50% stenosis is seen due to a noncalcified plaque on the origin of right vertebral artery on the curved multiplane reconstructed computed tomographic angiography.
Figure 2 A 68-year-old-woman with vertigo. Right vertebral artery hypoplasia is seen on the 3D volume rendered computed tomographic angiography.
Figure 3 Vertebral artery segments are shown on the 3D volume rendered coronal and sagittal CTA images. CTA = computed tomography angiography.
Figure 4 A 65-year-old-man with vertigo. Basilar artery hypoplasia is seen on the sagittal (A) and coronal (B) maximum-intensity projection multiplane reconstructed computed tomographic angiography images.
Figure 5 Sagittal oblique maximum-intensity projection (MIP) image shows the kinking and tortuosity of the V1 segment of left vertebral artery.
In patients with atheromas, stenosis measurements were made by applying North American Symptomatic Carotid Endarterectomy Trial–style ratio calculations to the vertebral and basilar arteries.[14]
On a curved multiplanar reconstructed image the smallest diameter of the atheromatous vessel was compared to the normal vessel diameter at the distal part of this segment; thus, the percentage of stenosis and the open segment was calculated.
2.4 Magnetic resonance imaging
The study was performed with 1.5-T MRI (Optima 450W, General Electric Medical Systems, Milwaukee, WI). Head coil and immobilization devices were used. The b value was 1000 s/mm2 on diffusion-weighted imaging. Image analysis was performed on a workstation (GE Advantage Workstation AW4.2_08) using functool 2 image analysis software (GE Medical Systems).
2.5 Statistical analysis
The coherence between normal distribution with the data of the patient and the control groups was analyzed. Independent-samples t test was used in variables with normal distribution, and Mann–Whitney U test in non-normal distribution.
The difference of categorical variable distribution according to groups was analyzed with χ2 and/or Fisher exact test.
Descriptive statistics were average ± standard deviation, median, minimum–maximum, and percentage.
Analysis was evaluated with SPSS 11.5 package program (SPSS Inc, Chicago, IL). Margin of error was considered to be 0.05.
3 Results
A total of 249 patients, of whom 129 (51.8%) had central vertigo and 120 (48.2%) were controls, were included in the study. The control group's ages were between 36 and 85 years with an average of 59.8; the vertigo group's ages were between 31 and 81 years with an average of 62.2.
Of the cases in the vertigo group, 57 (44.2%) were female and 72 (55.8%) were male. In the control group, 54 (45%) were female and 66 (55%) were male. There was no statistically significant difference in terms of age and gender between the vertigo group and the control group (P > 0.05).
The mean diameters of right vertebral arteries in vertigo and control groups were found to be 3.72 ± 1.15 and 3.94 ± 0.9 mm, respectively; the mean diameters of left vertebral arteries were found to be 3.97 ± 1.1 and 4.18 ± 0.8 mm, respectively; and the mean diameters of basilar arteries were found to be 3.33 ± 0.6 and 3.44 ± 0.7 mm, respectively. Although mean diameters of the right and left vertebral arteries and basilar arteries were less in vertigo patients, they were not statistically significant (P > 0.05) (Table 1).
Table 1 Vertebral and basilar artery diameter distribution.
As seen in Table 2, vertebral artery hypoplasia and ≥50% stenosis was more common in vertigo cases (P = 0.000, <0.001). Of the total 78 vertigo cases with ≥50% stenosis, the stenotic segment in 54 (69.2%) patients was in V1 segment, in 9 (11.5%) patients in V2 segment, in 2 (2.5%) patients in V3 segment, and in 13 (16.6%) patients in V4 segment.
Table 2 Distribution of artery vertebral artery hypoplasia and stenosis within the groups.
Dissecting aneurysm and fibromuscular hyperplasia were not detected in vertigo and control groups. In the vertigo group, 8 (6.2%) patients had vertebral artery hypoplasia associated with ≥50% stenosis of contralateral vertebral artery (Fig. 6A–C). Five of 8 patients were treated with percutaneous transluminal angioplasty and stenting. Three patients did not accept endovascular treatment. In the control group hypoplastic vertebral artery with contralateral vertebral artery stenosis and bilateral vertebral artery stenosis was not detected.
Figure 6 3D volume rendered coronal (A) and curved multiplanar reconstruction coronal (B and C) images show right vertebral artery stenosis associated with left vertebral artery hypoplasia.
One patient with vertigo had bilateral vertebral artery hypoplasia (Fig. 7A and B); 2 patients had basilar artery hypoplasia accompanied with right vertebral artery hypoplasia.
Figure 7 (A and B) Curved multiplanar reconstructed coronal CT images show bilateral hypoplastic vertebral arteries of a vertigo patient. CT = computed tomography.
Five of 78 (6.4%) patients with vertigo had bilateral vertebral artery stenosis and 2 of them were treated with stenting. Surgical treatment was not performed in both groups. Antiplatelet and anticoagulant therapies were given to the 61 (78.2%) vertigo cases with ≥50% stenosis.
Left vertebral artery originated from the aortic arch between the main carotid artery and the left subclavian artery orifice in 12 (9.3%) of the vertigo patients and in 9 (7.5%) of the controls. There was no significant difference between the groups (P > 0.05).
Of the vertigo cases, 9 (6.9%) had vertebral artery V1 segment tortuosity, and 17 (13.1%) had basilar artery tortuosity. Of the control group, 8 (6.6%) had vertebral artery V1 segment tortuosity, and 13 (10.8%) had basilar artery tortuosity. There was no significant difference between the 2 groups (P > 0.05).
Both vertigo and control groups had similar basilar artery hypoplasia and ≥50% stenosis rates (P = 0.800, >0.05) (Table 3).
Table 3 Distribution of basilar artery hypoplasia and stenosis within the groups.
4 Discussion
Atherosclerosis is the most common cause of vertebrobasilar disorders. Stenosis of vertebral and basilar arteries secondary to atherosclerosis leads to vertebrobasilar insufficiency and poor posterior circulation. Vertigo, ataxia, dysarthria, diplopia, visual disturbances, and weakness may be seen in vertebrobasilar insufficiency and ischemia.[4,5] In the presented study, vertebral artery hypoplasia and ≥50% stenosis were more common in central vertigo cases without stroke compared to in the control group. In patients without stroke signs on DWI, the cause of central vertigo was believed to be TIA or vertebrobasilar insufficiency. A single vertebral artery with normal calibration may sufficiently supply the basilar artery. However, if severe bilateral vertebral artery stenosis or occlusion is present, treatment is indicated.[12,13] Treatment options may be medical, endovascular, or surgical. Medical treatment includes antiplatelet and anticoagulant therapy.
Surgery is not considered in most centers because of the technical difficulties. It can be performed when medical treatment fails or the anatomy is unfavorable for endovascular treatment.[12–15] Medical and endovascular treatments were implemented in the patients in our study. In central vertigo cases, CTA may help reveal vertebrobasilar stenosis, anatomic variations, and tortuosity. Being aware of anatomic variations and tortuosity is important before endovascular treatment and surgery because severe tortuosity can preclude safe stent placement.[12–15]
Atherosclerotic stenosis of the posterior circulation is most often seen at vertebral artery origin. At the intracranial segment of the vertebral artery, stenosis is most commonly seen at vertebrobasilar junction level. Another common location is right before branching to posterior inferior cerebellar artery, distal from the dural penetration.[16,17] In the presented study, the most common place of stenosis was at the origin of the vertebral artery. Patients with stenosis of vertebral artery origin were found to have a high risk for vertebrobasilar circulation ischemia.
TIA and stroke can be seen and the risk of recurrent stroke after TIA and minor stroke was found to be as high as that of carotid stroke in vertebrobasilar stenotic disease.[1] A prospective study revealed that the patients who have vertebral stenosis with vertebrobasilar TIA and minor stroke have a 30% risk of recurrent stroke in the first month.[18] These patients may benefit from medical or endovascular treatment. Therefore, it is important to show stenosis of vertebral artery for starting the therapy.[17,18]
In this study, vertebral artery hypoplasia was more commonly seen in vertigo cases than in the control group. However, in the literature, a relationship between vertebrobasilar artery hypoplasia and posterior circulatory strokes has been reported.[19,20] It is important that in the presented study vertebral artery hypoplasia was seen more frequently in vertigo cases without stroke compared to in the control group. Hypoplasia of the vertebral arteries may cause vertigo by decrease of blood supply to the cerebellum and cerebral peduncle. It has been reported that vertebral artery hypoplasia may be commonly accompanied by basilar artery hypoplasia, thus causing posterior circulatory ischemia. Bilateral vertebral artery hypoplasia may present with episodic vertigo attacks.[21] A single vertebral artery with normal calibration may sufficiently supply the basilar artery. However, bilateral vertebral artery hypoplasia or unilateral vertebral artery hypoplasia associated with contralateral vertebral artery stenosis may impair the sufficient blood flow through the posterior circulation.[22]
There are studies reporting that vertigo may also be seen in basilar artery stenosis and the vertigo attacks may improve after stenting of the stenotic arteries.[23] However, no relationship was detected between basilar artery hypoplasia or stenosis and vertigo in our study. The small number of participants with basilar artery hypoplasia and stenosis in both vertigo and control group may have led to this result in the presented study.
In recent years, studies of vertigo related to vertebral and basilar artery tortuosity have been presented. Vertebral artery tortuosity is thought to be caused by mechanical pressure on the artery due to head position resulting in ischemia. It has been reported that basilar artery tortuosity may lead to occlusion and atherosclerosis, thus decreasing the distal blood flow in tortuous vessels.[24,25] In the presented study there was no significant difference between vertebral and basilar artery tortuosity in the vertigo group compared to in the control group.
Vertigo patients and control participants were in the elderly group, and the presence of similar risk factors may have created this consequence.
Diagnostic approach for vertigo patients is complex. Detailed patient history, physical examination, neuro-otological tests, and imaging finding are used.[3–26] It has been shown that MRI is useful in the detection of serious acute vertigo cases related to small posterior fossa infarctions and in the differentiation from vestibular neuritis.[27] Contrast-enhanced MRA has frequently shown pseudostenosis of vertebral artery origin because of weak spatial resolution, intravoxel dephasing, and motion artifact caused by cardiac pulsation and respiration.[28] Khan et al[11] performed a systematic literature review to evaluate the accuracy of duplex ultrasound, contrast-enhanced MRA, and CTA in detecting severe vertebral artery stenosis. The sensitivity and specificity of CTA (100% and 93.9%, respectively) were higher versus those of contrast-enhanced MRA (95.2% and 94.8%, respectively) in detecting severe vertebral artery stenosis. In a recent study comparing contrast-enhanced MRA, CTA, and duplex sonography in detecting ≥50% stenosis of vertebral artery, contrast-enhanced MRA had the highest sensitivity and specificity (83% and 91%, respectively). CTA had good sensitivity (68%) and excellent specificity (92%).[13] On the other hand, CTA had better accessibility, high spatial resolution, and short scanning time than MRA. CTA has better temporal resolution and therefore is less affected by the motion of cardiac pulsation and respiration. It is cheaper and suitable for patients with contraindications to MRI. However, CTA has problems involving radiation, and a potentially nephrotoxic contrast agent as well as inaccuracy for heavily calcified stenosis.[28] Because CTA has higher temporal and spatial resolution than MRA and is less affected by motion artifact and pseudostenosis, we recommend evaluating patients with central vertigo with CTA after brain MRI.
Some limitations exist in the presented study. Vascular risk factors such as ischemic heart diseases and smoking were not included. The patients included in the study were elderly and with higher ischemic heart disease risks. Further limitations were small number of patients with >50% basilar artery stenosis and basilar artery hypoplasia of the controls and vertigo patients.
This study showed that CTA may be helpful to clarify the association between abnormal CTA findings of vertebral arteries and central vertigo. It is believed that CTA may be useful in the arrangement of clinical management.
Abbreviations: CTA = computed tomography angiography, DWI = diffusion-weighted imaging, MRA = magnetic resonance angiography, MRI = magnetic resonance imaging, PACS = picture archiving and communication system, TIA = transient ischemic attack.
The authors have no funding and conflicts of interest to disclose.
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Medicine (Baltimore)Medicine (Baltimore)MEDIMedicine0025-79741536-5964Wolters Kluwer Health 28328810MD-D-17-0067210.1097/MD.0000000000006319063193300Research ArticleObservational StudyPrediction of the mid-tracheal level using surface anatomical landmarks in adults Clinical implication of endotracheal tube insertion depthJang Young-Eun MDKim Eun-Hee MDSong In-Kyung MDLee Ji-Hyun MDRyu Ho-Geoul MD, PhDKim Hee-Soo MD, PhDKim Jin-Tae MD, PhD∗Hanaoka. Kazuo Department of Anesthesiology and Pain Medicine, Seoul National University Hospital, Seoul National University College of Medicine, Seoul, Republic of Korea.∗ Correspondence: Jin-Tae Kim, Department of Anesthesiology and Pain Medicine, Seoul National University Hospital, Seoul National University College of Medicine, 101 Daehakno, Jongnogu, Seoul 110-744, Republic of Korea (e-mail: jintae73@gmail.com).3 2017 24 3 2017 96 12 e63193 2 2017 9 2 2017 13 2 2017 Copyright © 2017 the Author(s). Published by Wolters Kluwer Health, Inc.2017This is an open access article distributed under the terms of the Creative Commons Attribution-Non Commercial License 4.0 (CCBY-NC), where it is permissible to download, share, remix, transform, and buildup the work provided it is properly cited. The work cannot be used commercially without permission from the journal. http://creativecommons.org/licenses/by-nc/4.0Abstract
Endotracheal tube (ETT) should be placed at the optimal level to avoid single lung ventilation or accidental extubation. This study was performed to estimate the mid-tracheal level by using surface anatomical landmarks in adult patients.
Neck computed tomography images of 329 adult patients between the ages of 16 and 79 years were reviewed. In the midline sagittal plane, the levels corresponding to the vocal cords, cricoid cartilage, suprasternal notch, manubriosternal junction, and carina were identified. The surface distances from the cricoid cartilage to the suprasternal notch (extCC-SSN) and that from the suprasternal notch to the manubriosternal junction (extSSN-MSJ) were measured. The relationship between mid-tracheal level and the surface distances was analyzed using Bland–Altman plot.
The difference between the extCC-SSN and the mid-tracheal level was −6.6 (12.5) mm, and the difference between the extSSN-MSJ and the mid-tracheal level was −19.2 (6.1) mm. The difference between the extCC-SSN and the mid-tracheal level was smaller in females compared with males [−1.7 (11.7) mm vs −12.8 (10.7) mm; P < 0.001].
The mid-tracheal level, which is helpful in planning the insertion depth of an ETT, can be predicted by the surface distance between the cricoid cartilage and suprasternal notch in adults, especially in females.
Keywords
depth of intubationintratrachealintubationsurface anatomical landmarksOPEN-ACCESSTRUE
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1 Introduction
The endotracheal tube (ETT) should be placed at the optimal level to avoid inadvertent complication. If the ETT is too deep, it increases the risk of unintended single lung ventilation. On the other hand, if the ETT is too shallow, it may cause vocal cord injury by the ETT balloon or accidental extubation.
There are many methods for determining the appropriate depth of ETT in adults; fixed insertion depth according to sex (23 and 21 cm from the upper incisors in adult males and females, respectively), the use of depth marks on the ETT, suprasternal palpation of the ETT tip or cuff, and bilateral auscultation.[1–5] Although chest radiography and bronchoscopy are considered an accurate method, they are not always feasible and the costs are considerable. Considering the individual variation in the length of the trachea, using fixed depths or marks on the ETT may result in inadequate placement of the ETT.
To reduce the risk of single lung ventilation or vocal cord injury, the segment between the proximal edge of the cuff and the ETT tip should be placed at the mid-trachea level. If the length of the trachea can be predicted at bedside before intubation, the ETT can be placed at a safe depth for each patient.
The purpose of this study was to determine whether surface anatomical landmarks can be used to predict the mid-tracheal level in adult patients.
2 Methods
Neck computed tomography (CT) images of adults obtained between 2009 and 2014 were reviewed by a single reviewer after obtaining approval form Seoul National University Hospital Institutional Review Board (July 17, 2015/No. 1507-050-687). Patients’ informed consents were waived. Patients with laryngeal, tracheal, or thoracic abnormalities, tracheostomy or significant tracheal deviation caused by mass lesions were excluded. In addition, poor CT image quality, absent sagittal CT images, CT images that did not cover the entire trachea, or CT images taken in neck hyperextension (Boidin angle >130° on scout view) or hyperflexion (Boidin angle < 110° on scout view) position were also excluded.[6,7]
3 Analysis of CT images
All measurements were made in the midline sagittal plane. Levels of subglottic and tracheal airway segments that include the vocal cords (VC), the cricoid cartilage (CC), and the carina were identified using the method described by Sirisopana et al.[8] The vocal cords were identified as the most cranial level of the upper airway, with a teardrop shape below the laryngeal ventricle. Anatomic level of suprasternal notch (SSN) was identified as the most superior level of the manubrium. The level of manubriosternal junction (MSJ) was defined as the middle level between the manubrium and the body of the sternum where the second rib attaches to the sternum.[9] The level of carina was defined as the bifurcation of right and left main bronchus and identified by the figure 8 shaped lumen.
The external locations of the CC, SSN, and MSJ were defined on the skin surface. The distances between the external points of the CC and the SSN (extCC-SSN), and those of the SSN and the MSJ (extSSN-MSJ) were measured.
The distances between the subglottic structures at the levels of the VC, the CC, SSN, and carina were measured. Tracheal length was calculated as the summation of the distances measured from the VC to the carina. All measurements are shown in Fig. 1. The mid-trachea level was calculated from tracheal length and the ideal position of ETT is shown in Fig. 2.
Figure 1 Identification of subglottic segments on axial view (right), and defining the distances between subglottic segments on sagittal view (left) in a 45-year-old male patient. CC = cricoid cartilage, extCC-SSN = the surface distances from the cricoid cartilage to the suprasternal notch, extSSN-MSJ = the surface distances from the suprasternal notch to the manubriosternal junction, MSJ = manubriosternal juction, SSN = suprasternal notch, VC = vocal cord, Tracheal length = a + b + c + d.
Figure 2 The ideal position of endotracheal tube (ETT) to minimize the risk of endobronchial intubation and vocal cord injury. The mid-point between the proximal edge of the cuff and the ETT tip was matched to the level of the middle of the trachea (MTL), which was calculated from the tracheal length. CC = cricoid cartilage, ETT = endotracheal tube, MSJ = manubriosternal juction, MTL = the level of the middle of the trachea, SSN = suprasternal notch, VC = vocal cord.
4 Statistical analysis
The correlations between age, height, weight, and tracheal length were analyzed using linear regression. The relationships between surface measurements and the mid-tracheal level were analyzed with Bland–Altman plot. An unpaired t test was used to compare the difference between male and female. A P value <0.05 was considered statistically significant. Values are presented as mean value ± standard deviation (SD).
5 Results
A total of 329 adult patients (16–79 years) were reviewed. Table 1 shows the demographic data of the patients and measured distances. The distance between the CC and the SSN was longer in females (P < 0.001), whereas distances between the VC and the CC, the SSN and the carina, and the tracheal length were longer in males (P < 0.001). The extCC-SSN was longer in females (P < 0.001), whereas extSSN-MSJ was longer in males (P < 0.001).
Table 1 Demographic data and measured distances between subglottic structures of trachea, external landmarks, and calculated tracheal length.
The calculated tracheal length was 131.9 (10.3) mm and ranged from 106.0 to 169.8 mm. Tracheal length showed weak correlation with height (r2 = 0.2188) and weaker correlation with age (r2 = 0.0004) and weight (r2 = 0.0466) (Fig. 3).
Figure 3 Relationship between age, height, weight, and tracheal length.
The calculated mid-tracheal level was 66.0 ± 5.1 mm from the VC. Bland–Altman plots showing the difference between the mid-tracheal level and the surface measurements are shown in Fig. 4. The bias was calculated by subtracting the mid-tracheal level from the surface measurements. The difference between the extCC-SSN and the mid-tracheal level was −6.6 (12.5) mm, and the difference between the extSSN-MSJ and the mid-tracheal level was −19.2 (6.1) mm.
Figure 4 Bland–Altman plots showing the agreement between the mid-tracheal level (MTL) and the surface measurements of surface anatomical landmarks. (Left) The bias (subtraction of the mid-tracheal level from the surface distance from the cricoid cartilage to the suprasternal notch) and 95% limit of agreement as the mean difference were −6.6 [−31.1 to 17.9] (mm). (Right) The bias (subtraction of the mid-tracheal level from the surface distance from the suprasternal notch to the manubriosternal junction) and 95% limit of agreement as the mean difference were −19.2 [−31.1 to −7.2] (mm). extCC-SSN = the surface distances from the cricoid cartilage to the suprasternal notch, extSSN-MSJ = the surface distances from the suprasternal notch to the manubriosternal junction, MTL = the level of the middle of the trachea.
Figure 5 shows the Bland–Altman plots of the difference between the extCC-SSN and the mid-tracheal level in female and male patients. The calculated mid-tracheal level was 64.5 (4.6) mm in females and 67.9 (5.0) mm in males. The difference between the extCC-SSN and the mid-tracheal level was −1.7 (11.7) mm in females and −12.8 (10.7) mm in males (P < 0.001).
Figure 5 Bland–Altman plots of female (left) and male (right) patients showing the agreement between the mid-tracheal level (MTL) and the surface the surface distance from the cricoid cartilage from the suprasternal notch. (Left) The bias (subtraction of the mid-tracheal level from the surface distance from the cricoid cartilage to the suprasternal notch) and 95% limit of agreement as the mean difference were −1.7 [−24.6 to 21.2] (mm) in females. (Right) The bias (subtraction of the mid-tracheal level from the surface distance from the cricoid cartilage to the suprasternal notch) and 95% limit of agreement as the mean difference were −12.8 [−33.8 to 8.2] (mm) in males. extCC-SSN = the surface distances from the cricoid cartilage to the suprasternal notch, MTL = the level of the middle of the trachea.
6 Discussion
This study showed that mid-tracheal level could be estimated by the surface distance between the CC and the SSN (extCC-SSN). Compared with males, extCC-SSN more accurately predicts the mid-tracheal level in females. In clinical practice, physicians can use extCC-SSN to determine the depth of ETT so that the segment between the proximal edge of the cuff and the ETT tip lies at the mid-tracheal level.
There are several studies that used the distance between the surface anatomical landmarks to estimate the airway length and the optimal insertion depth of endotracheal tube.[10,11] Lee et al[10] showed that the distance between the upper incisor and the manubriosternal angle in the neck extension position correlates with the distance between the upper incisor and the carina in the neutral neck position. Evron et al[11] used the sum of the 2 distances from the mouth angle to the jaw angle and from the jaw angle to the sternal manubrium to determine the depth of ETT. However, these methods are complicated than single measurement of extCC-SSN due to the difficulty in locating the sternal manubrium, more than 1 measurement, and the need for full neck extension.
The physicians can easily apply our method with a simple measurement of the extCC-SSN to estimate the mid-tracheal level, and apply this depth during endotracheal intubation. However, according to previous studies in adults, flexion and extension of the neck from neutral position are associated with the inward and outward movements of the ETT.[7,12] Conrardy et al[12] showed that the orally intubated ETT can move 1.5 (range 0.5–2.0) cm toward the carina during flexion and 2.4 (range 1.3–4.3) cm away from the carina during extension. Kim et al[7] showed that the ETT can migrate 1.3 (SD 0.6; range 0.5–2.5) cm toward the carina during flexion and 1.7 (SD 0.8; range 0.4–3.1) cm during extension. Therefore, the position of the neck should be considered when determining the optimal depth of the ETT.
There are several limitations in the present study. First, this study was a retrospective analysis of CT images and the distances were measured in the neutral position. Second, since the VC is used as a baseline of the depth of intubation in our method, it can be difficult to apply our method to patients with high Cormack grades. Lastly, the efficacy of this method is yet to be demonstrated in clinical practice.
In conclusion, the mid-tracheal level, which is considered the optimal depth of ETT, can be predicted by the surface distance between the CC and SSN in adults, especially in females.
Abbreviations: CC = cricoid cartilage, CT = computed tomography, ETT = endotracheal tube, extCC-SSN = the surface distances from the cricoid cartilage to the suprasternal notch, extSSN-MSJ = the surface from the suprasternal notch to the manubriosternal junction, MSJ = manubriosternal junction, SSN = suprasternal notch, VC = vocal cords.
The authors have no conflicts of interest to disclose.
==== Refs
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Endobronchial intubation: a preventable complication . Anesthesiology
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[2] Brunel W Coleman DL Schwartz DE
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Intubation guide marks for correct tube placement. A clinical study . Anaesthesia
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[4] McKay WP Klonarakis J Pelivanov V
Tracheal palpation to assess endotracheal tube depth: an exploratory study . Can J Anaesth
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[5] Sugiyama K Yokoyama K
Reliability of auscultation of bilateral breath sounds in confirming endotracheal tube position . Anesthesiology
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[7] Kim JT Kim HJ Ahn W
Head rotation, flexion, and extension alter endotracheal tube position in adults and children . Can J Anaesth
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[8] Sirisopana M Saint-Martin C Wang NN
Novel measurements of the length of the subglottic airway in infants and young children . Anesth Analg
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[9] Chukwuemeka A Currie L Ellis H
CT anatomy of the mediastinal structures at the level of the manubriosternal angle . Clin Anat
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[10] Lee BJ Yi JW Chung JY
Bedside prediction of airway length in adults and children . Anesthesiology
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[11] Evron S Weisenberg M Harow E
Proper insertion depth of endotracheal tubes in adults by topographic landmarks measurements . J Clin Anesth
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[12] Conrardy PA Goodman LR Lainge F
Alteration of endotracheal tube position. Flexion and extension of the neck . Crit Care Med
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PMC005xxxxxx/PMC5371448.txt |
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Medicine (Baltimore)Medicine (Baltimore)MEDIMedicine0025-79741536-5964Wolters Kluwer Health 28328811MD-D-17-0072110.1097/MD.0000000000006325063253300Research ArticleClinical Case ReportTreatment of great auricular neuralgia with real-time ultrasound-guided great auricular nerve block A case report and review of the literatureJeon Younghoon MD, PhDaKim Saeyoung MD, PhDb∗Hanaoka. Kazuo a Department of Anesthesiology and Pain Medicine, School of Dentistry, Kyungpook National Universityb Department of Anesthesiology and Pain Medicine, Kyungpook National University Hospital, Daegu, Korea.∗ Correspondence: Saeyoung Kim, Department of Anesthesiology and Pain Medicine, School of Medicine, Kyungpook National University, 130, Dongdeok-ro, Jung-gu, Daegu 41944, Korea (e-mail: saeyoung@knu.ac.kr).3 2017 24 3 2017 96 12 e63255 2 2017 14 2 2017 15 2 2017 Copyright © 2017 the Author(s). Published by Wolters Kluwer Health, Inc.2017This is an open access article distributed under the terms of the Creative Commons Attribution-Non Commercial-No Derivatives License 4.0 (CCBY-NC-ND), where it is permissible to download and share the work provided it is properly cited. The work cannot be changed in any way or used commercially without permission from the journal. http://creativecommons.org/licenses/by-nc-nd/4.0Abstract
Rationale:
The great auricular nerve can be damaged by the neck surgery, tumor, and long-time pressure on the neck. But, great auricular neuralgia is very rare condition. It was managed by several medication and landmark-based great auricular nerve block with poor prognosis.
Patient concerns:
A 25-year-old man presented with a pain in the left lateral neck and auricle.
Diagnosis:
He was diagnosed with great auricular neuralgia.
Interventions:
His pain was not reduced by medication. Therefore, the great auricular nerve block with local anesthetics and steroid was performed under ultrasound guidance.
Outcomes:
Ultrasound guided great auricular nerve block alleviated great auricular neuralgia.
Lessons:
This medication-resistant great auricular neuralgia was treated by the ultrasound guided great auricular nerve block with local anesthetic agent and steroid. Therefore, great auricular nerve block can be a good treatment option of medication resistant great auricular neuralgia.
Keywords
cervical plexusgreat auricular nervenerve blockneuralgiaultrasonographyOPEN-ACCESSTRUE
==== Body
1 Introduction
The great auricular nerve is the largest sensory branch of superficial branches of the cervical plexus, arising from C2 and C3 spinal roots. It passes vertically upward over the sternocleidomastoid muscle (SCM) providing sensory innervations for the skin of auricle, lower face, and upper neck.[1] It can be damaged by the neck surgery,[2–4] tumor,[5] and prolonged pressure on the neck.[6,7] But, great auricular neuralgia rarely occurs.
We report the first description of great auricular neuralgia, which was treated successfully with the ultrasound guided great auricular nerve block using local anesthetic agent and steroid. A signed written consent was obtained from the patient for this case report.
2 Case report
A 25-year-old man was referred to our clinic with a 10-day history of pain in the left lateral neck and auricle. Ten days before his presentation, his pain suddenly developed after sleeping with the left side of his head against desk. His pain was characterized by constant burning or aching pain and intermittent sharp, lancinating pain over the left auricle and lateral neck area. His pain was rated at an intensity of 7 on the point numeric rating scale (NRS) from 0 (no pain) to 10 (worst pain imaginable). The pain was often provoked by rotation of his head to the right side and no trigger zone was found. General neurological and otorhinological examination showed no abnormal findings. In addition, there were no abnormalities in the magnetic resonance imaging of the neck and brain. His clinical diagnosis of great auricular neuralgia was made from the pain characteristics and painful region and he was treated with oral pregabalin (150 mg twice a day), amitriptyline (10 mg once a day), and tramadol (50 mg twice a day) for 9 days. But, despite this medication his pain did not reduce. Therefore, we decided to perform the great auricular nerve block. The great auricular nerve was identified at the level of the fourth cervical spine in the axial sonographic view using high-frequency linear array transducer (Fig. 1). The great auricular nerve was located at dorsal border of SCM. We inserted a 25-gauge block needle using in-plane approach and performed great auricular nerve block with 1% lidocaine 0.5 mL and triamcinolone 10 mg. One hour later, his pain was rated 2 on the NRS. Five days after the great auricular nerve block, his pain had completely disappeared and stopped taking pain medication. At 6 months follow-up after the great auricular nerve block, he remained symptom free.
Figure 1 The axial sonographic view of the great auricular nerve (arrow) above the sternocleidomastoid muscle (SCM).
3 Discussion
The great auricular neuralgia is a very rare disorder. The pathogenesis of great auricular neuralgia remained unknown clearly. It may be idiopathic or secondary to surgery or trauma of head and neck or prolonged pressure on the neck. Diagnosis of great auricular neuralgia is based primarily on the history and physical findings—specifically, the specific pain characters including intermittent, electric shock-like, and distressing nature and well-localized cutaneous region of the pain.[8] Rotation of head to the opposite side often provokes the pain over the dermatome of great auricular nerve, which sometimes can radiate to upper neck, temporal, and occipital area.[9] In the present cases, definite causative factors of great auricular neuralgia were not identified but the great auricular neuralgia is presumed to be caused by compression of head and neck during sleep.
Numerous analgesics including anticonvulsants, antidepressants, and opioids are currently used for the treatment of neuropathic pain. However, neuropathic pain disorders including trigeminal neuralgia, glossopharyngeal neuralgia, postherpetic neuralgia, and occipital neuralgia are often difficult to treat with such drugs. It was reported that administration of gabapentin 1200 mg daily was effective to reduce great auricular neuralgia.[8] However, in the present case, treatment with pregabalin 300 mg, amitriptyline 10 mg, and tramadol 100 mg did not reduce the neuralgic pain. Nerve block is useful in the diagnosis and treatment of painful conditions. In the preclinical and clinical studies, it was shown that early application of nerve block can prevent or reduce neuropathic pain.[10,11] Therefore, we decided to turn our therapeutic focus toward nerve block.
Great auricular nerve block was achieved via superficial cervical plexus block using large volumes of local anesthetics. However, ultrasound visual guidance technique can identify target nerve, which allows highly selective block of the nerve with smaller volume of local anesthetics, leading to better efficacy for performing regional and peripheral nerve block.[12] In the present case, great auricular nerve block was performed with 1% lidocaine 0.5 mL and triamcinolone 10 mg. A combination of local anesthetics and steroid was found to be more effective than local anesthetics alone in the treatment of neuropathic symptoms and signs following nerve injury.[13] Administration of steroid around injured nerve may alleviate edema and provide analgesia through its anti-inflammatory and membrane stabilising actions, lead to hastening recovery of the damaged nerves.[14,15]
In conclusion, the great auricular neuralgia is a very rare disorder. In the present case, great auricular neuralgia was resistant to medications but was successfully treated by a real-time ultrasound-guided great auricular nerve block using local anesthetic agent and steroid. Therefore, great auricular nerve block can be a good treatment option of medication resistant great auricular neuralgia.
Abbreviations: NRS = numeric rating scale, SCM = sternocleidomastoid muscle.
The authors have no conflicts of interest to disclose.
==== Refs
References
[1] Peuker ET Filler TJ
The nerve supply of the human auricle . Clin Anat
2002 ;15 :35 –7 .11835542
[2] Lefkowitz T Hazani R Chowdhry S
Anatomical landmarks to avoid injury to the great auricular nerve during rhytidectomy . Aesthet Surg J
2013 ;33 :19 –23 .23277616
[3] Moss CE Johnston CJ Whear NM
Amputation neuroma of the great auricular nerve after operations on the parotid gland . Br J Oral Maxillofac Surg
2000 ;38 :537 –8 .11010790
[4] Matarasso A Elkwood A Rankin M
National plastic surgery survey: face lift techniques and complications . Plast Reconstr Surg
2000 ;106 :1185 –95 .11039390
[5] Ginsberg LE Eicher SA
Great auricular nerve: anatomy and imaging in a case of perineural tumor spread . AJNR Am J Neuroradiol
2000 ;21 :568 –71 .10730653
[6] Arias M Arias-Rivas S Perez M
Numb ears in resurrection: great auricular nerve injury in hanging attempt . Neurology
2005 ;64 :2153 –4 .15985597
[7] LaPrade CM Foad A
Greater auricular nerve palsy after arthroscopic anterior-inferior and posterior-inferior labral tear repair using beach-chair positioning and a standard universal headrest . Am J Orthop (Belle Mead NJ)
2015 ;44 :188 –91 .25844590
[8] Maimone-Baronello M Piccoli F La Bella V
Great auricular neuralgia: a case report . Headache
2003 ;43 :1005 –6 .14511279
[9] Robertson CE Garza I
Great auricular neuralgia: case series . J Headache Pain
2013 ;14 suppl 1 :161 –161 .
[10] Xie W Strong JA Zhang JM
Early blockade of injured primary sensory afferents reduces glial cell activation in two rat neuropathic pain models . Neuroscience
2009 ;160 :847 –57 .19303429
[11] Yoo HS Nahm FS Lee PB
Early thoracic sympathetic block improves the treatment effect for upper extremity neuropathic pain . Anesth Analg
2011 ;113 :605 –9 .21778335
[12] Jeon YH
Easier and safer regional anesthesia and peripheral nerve block under ultrasound guidance . Korean J Pain
2016 ;29 :1 –2 .26839663
[13] Eker HE Cok OY Aribogan A
Management of neuropathic pain with methylprednisolone at the site of nerve injury . Pain Med
2012 ;13 :443 –51 .22313580
[14] Johansson A Sjolund B
Nerve blocks with local anesthetics and corticosteroids in chronic pain: a clinical follow-up study . J Pain Symptom Manage
1996 ;11 :181 –7 .8851376
[15] Kim SY Kim DG Park YM
Psoas compartment block for treatment of motor weakness and pain following herpes zoster . Korean J Pain
2017 ;30 :62 –5 .28119773
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PMC005xxxxxx/PMC5371453.txt |
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Medicine (Baltimore)Medicine (Baltimore)MEDIMedicine0025-79741536-5964Wolters Kluwer Health 28328816MD-D-16-0686810.1097/MD.0000000000006348063484200Research ArticleClinical Case ReportA case report: Liraglutide as a novel treatment option in late dumping syndrome Chiappetta Sonja MD∗Stier Christine MD, PhDVanar. Vishwas Department of Obesity and Metabolic Surgery, Sana Klinikum Offenbach, Offenbach am Main, Germany.∗ Correspondence: Sonja Chiappetta, Department of Obesity and Metabolic Surgery, Sana Klinikum Offenbach, Starkenburgring 66, 63069 Offenbach am Main, Germany (e-mail: sonja1002@gmx.de).3 2017 24 3 2017 96 12 e634814 11 2016 14 2 2017 18 2 2017 Copyright © 2017 the Author(s). Published by Wolters Kluwer Health, Inc.2017This is an open access article distributed under the terms of the Creative Commons Attribution-Non Commercial-No Derivatives License 4.0 (CCBY-NC-ND), where it is permissible to download and share the work provided it is properly cited. The work cannot be changed in any way or used commercially without permission from the journal. http://creativecommons.org/licenses/by-nc-nd/4.0Abstract
Rationale:
Postprandial hyperinsulinemic hypoglycemia, known as late dumping syndrome, is a rare but often misdiagnosed complication after gastric surgery. The pathophysiological mechanisms are poorly understood and the treatment of this syndrome is challenging.
Patient concerns:
New-onset postsurgical late dumping syndrome after Toupet fundoplication.
Diagnoses:
Sigstad Score, OGTT, CGM.
Interventions:
Daily subcutaneous injection of liraglutide (0.6 mg and 1.2 mg).
Outcomes:
Reduction in fasting and postprandial peak insulin level with improvement in symptomatic hypoglycemic events.
Lessons:
Liraglutide may be a novel treatment option for postprandial hyperinsulinemic hypoglycemia after gastric surgery.
Keywords
gastric surgeryGLP-1hyperinsulinemic hypoglycemialate dumping syndromeliraglutideOPEN-ACCESSTRUE
==== Body
1 Introduction
Gastroesophageal reflux disease (GERD) is the most common upper gastrointestinal condition in Western countries, and its incidence is increasing worldwide because of the obesity epidemic. Laparoscopic posterior fundoplication is the standard surgical treatment for GERD, and the Nissen and Toupet fundoplications have low morbidity and excellent long-term functional outcomes.[1] Moreover Roux-en-Y gastric bypass is getting the new surgical treatment of choice in obese patients with GERD,[2] while gastric bypass surgery shows efficacy similar to that of traditional laparoscopic antireflux surgery in the control of GERD.[3] However, some of the anatomic and functional changes associated with these procedures can cause postoperative complications such as dysphagia, flatulence, distention, and gas-bloat syndrome. Postoperative postprandial hypoglycemia is another complication often reported after fundoplication in children,[4] and a few cases have been reported in adults.[5–9] The apparently high incidence in the pediatric literature suggests that it is an underdiagnosed complication in adults.[5]
Late dumping syndrome is a well-known side effect after gastric surgery and an often-described complication after obesity surgery. It is distinguished from early dumping, which occurs because of the rapid hyperosmolar influx of chyme into the small intestine, and leads to a volume overload and consequent release of gastrointestinal hormones and symptomatic circulatory disturbances. In late dumping syndrome, hyperinsulinemia leads to a hypoglycemic episode 2 to 3 hours after a meal.
The underlying cause of late dumping syndrome is thought to be either that the postoperatively elevated gastric inhibitory polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) levels lead to pancreatic beta cell hypertrophy,[10,11] which increases insulin output and hypoglycemic symptoms, or that changes in the distribution of carbohydrate receptors and transporters in the small intestine contribute to the pathophysiology.[12] These theories are supported by the observation that hyperinsulinemic hypoglycemia most frequently affects patients who have undergone resection of parts of the stomach, in which the gastrojejunostomy bypasses the pylorus. However, none of these theories is proven and none can explain the considerable time delay from surgery to the appearance of symptoms.
Treatment options for late dumping syndrome include dietary changes and medical treatment with glucosidase inhibitors such as acarbose[13] or somatostatin analogs.[14] In cases of treatment failure, partial or even total pancreatectomy is described as the surgical ultima ratio.[15] To address this treatment failure and the side effects of the drugs used currently, Abrahamsson et al[16] described a novel treatment option for postprandial hypoglycemia following gastric bypass surgery with GLP-1 analogs and reported a protective effect of GLP-1 analogs on pronounced symptoms of postprandial hypoglycemic episodes in 5 patients. Prospective randomized trials to define further the role of GLP-1 analogs in treating postprandial hypoglycemia are lacking but are urgently needed.
In this clinical case, we describe the successful use of a GLP-1 analog in treating refractory late dumping syndrome after fundoplication and a possible pathophysiological explanation for the resolution of symptoms.
2 Case presentation and management
A 52-year-old woman who was moderately overweight (BMI 29 kg/m2) and had severe reflux disease underwent a laparoscopic Toupet fundoplication. Twelve months after surgery, she developed episodes of severe symptomatic late dumping syndrome with the full spectrum of hypoglycemic symptoms. About 150 minutes after a meal, she felt palpitations, nausea, sweating, and weakness, which led to collapse. She had no history of diabetes or hypoglycemic symptoms before the operation.
Clinical evaluation included blood tests, functional X-ray examination, upper endoscopy, and magnetic resonance imaging of the upper abdomen. Diagnosis of symptomatic hyperinsulinemic hypoglycemia was made using the Sigstad score questionnaire,[17] an oral glucose tolerance test (OGTT) (Accu-Chek Dextro OGT Roche, Switzerland), and a continuous glucose measurement (CGM) (Dexcom G4 Nintamed, San Diego, California). During the OGTT, the serum insulin level in μU/mL, was quantified at the same time as each glucose measurement.
Treatment of late dumping syndrome included dietary changes and administration of acarbose. Dietary changes escalated the meal frequency to 5 to 6 per day, and the meal composition was shifted toward more protein and fiber, and less carbohydrates. Pharmaceutical treatment included administration of acarbose. Acarbose is an oral antidiabetic agent that inhibits the enzyme alpha-glucosidase and reduces the rate of digestion of carbohydrates. Fifty milligrams of acarbose were given before each meal, 3 times a day.
Due to treatment failure the decision to give liraglutide (Victoza, Novo Nordisk Pharma, Clayton, Carolina del Nord) as an off-label drug[16] was established and discussed with the patient, who agreed and signed an informed consent form for the off-label use of liraglutide and data sharing. Liraglutide is a GLP-1 analog that was approved by the European Commission in 2009 for the treatment of type 2 diabetes mellitus in adults and was approved by the US Food and Drug Administration in 2014 as a treatment option for chronic weight management when used with a reduced-calorie diet and physical activity. Liraglutide is known to increase pancreatic insulin production. The drug decelerates stomach emptying, which initiates the central inhibition of hunger feelings.[18] Liraglutide dosage was applied as recommended in the drug information from Liraglutide (Victoza, Novo Nordisk Pharma, USA) in the treatment of type 2 diabetes mellitus: Liraglutide was applied initially as a daily subcutaneous injection at a low dose of 0.6 mg per day, which was increased to 1.2 mg per day after 3 weeks. OGTT and CGM were performed without treatment, with a treatment of 0.6 mg liraglutide per day (at week 2) and with a treatment of 1.2 mg liraglutide per day (at week 4).
All clinical examinations showed normal postoperative findings 1 year after the fundoplication. There was no evidence of a neuroendocrine tumor. Sigstad score was positive for dumping syndrome with a score of 15. Dietary changes provided no improvement of the postprandial hypoglycemic episodes and intensification of treatment by administration of acarbose produced an insufficient therapeutic effect.
The CGM showed that 59% of all glucose values were in the hypoglycemic range. The Homeostatic Model Assessment of Insulin Resistance (HOMA-Index) was 6.6. The HbA1c level was 4.5% (25.7 mmol/mol).
The first baseline OGTT showed a fasting glucose level of 93 mg/dL and a fasting insulin level of 29 μU/mL. After oral carbohydrate stress during the OGTT, the glucose level increased to a maximum of 206 mg/dL at 30 minutes, after which the glucose level declined slowly to 180 mg/dL at 60 minutes and 146 mg/dL at 90 minutes. The insulin peak of 717 μU/mL was observed at 90 minutes. At that time, the blood glucose level had already started decreasing and was 146 mg/dL. This conjunction of an exaggerated, hyperinsulinemic insulin peak of 717 μU/mL with decreasing serum glucose level caused a rebound of considerable symptomatic hypoglycemia with a glucose level of 35 mg/dL at 150 minutes (Fig. 1).
Figure 1 The dynamics of insulin release during OGTT without liraglutide treatment. Note the lack of synchronization of the peak of insulin release to that of serum glucose level.
After 2 weeks of treatment with 0.6 mg liraglutide per day, another OGTT and CGM were performed. The patient showed a marginal improvement in the subjective hypoglycemic symptoms. The OGTT showed a different dynamic to the previous investigation, and the insulin levels were markedly lower than without treatment. The fasting glucose level was 88 mg/dL, which is in the normal range. The fasting insulin level of 19.3 μU/mL was two-thirds of the value without treatment. The peak insulin level was 311 μU/mL and appeared 30 minutes earlier, at 60 minutes. The peak glucose level occurred 30 minutes after the OGTT and was 155 mg/dL, which was 25% lower than without liraglutide treatment. There was only a 30 minutes time difference between the 2 peaks. A hypoglycemic glucose level was still observed, but this time it occurred after 180 minutes, which was 30 minutes later than without treatment. At 120 minutes, the glucose level was 76 mg/dL and the insulin level was 109 μU/mL. This resulted in hypoglycemia and a glucose concentration of 48 mg/dL 60 minutes later at 180 minutes. The patient still had symptoms, but they were considerably milder.
This was considered to be an insufficient treatment response, and the liraglutide dosage was boosted to 1.2 mg/day. The OGTT and CGM were repeated after 2 weeks of treatment. A further decrease in fasting insulin levels was observed to 10.7 μU/mL, which was one-third of the baseline fasting insulin value of 29 μU/mL. The fasting glucose level was considered normoglycemic at 83 mg/dL. The corresponding OGTT showed a peak in the insulin level of 413 μU/mL at 60 minutes.
The changes in the insulin and glucose courses were remarkable (Fig. 2). The corresponding CGM showed that the glucose level remained above 66 mg/dL and that 84% of all evaluated glucose values reached the target normoglycemia level. With continuing liraglutide treatment, the patient remains free of symptoms.
Figure 2 Relationship between the dynamics of insulin release during the OGTT with 1.2 mg liraglutide treatment. Note the optimal synchronization of the peaking of both serum glucose and insulin levels. The rapid decline in insulin output led to a rapid stabilization of serum glucose level and resolution of late dumping symptoms.
All procedures performed in this study involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards. Informed consent was obtained from the patient included in the study.
3 Discussion
Late dumping syndrome is a well-known side effect after gastric surgery, and treatment of this phenomenon is challenging. In our clinical case, late dumping syndrome developed after a Toupet fundoplication, a nonresecting gastric surgery procedure. Hyperinsulinemic hypoglycemia is an often-described postsurgical complication after fundoplication in children,[4] but only a few cases have been described in adults.[5–9]
In up to 40% of patients with GERD, delayed gastric emptying has been described preoperatively and is an independent risk factor for poor outcome after fundoplication in terms of both reflux and symptom control.[19] Fundoplication significantly accelerates gastric emptying.[20] Accelerated gastric emptying may give rise to a larger and earlier increase in plasma glucose, GLP-1, and GIP concentrations, and thus to reactive hypoglycemia.[10] Similar effects have been described after obesity surgery[21,22]; for example, there is a prevalence of up to 50% of postprandial hyperinsulinemic hypoglycemia after Roux-en-Y gastric bypass.[23] The key component is the rapid transit and appearance of nutrients in the small intestine, which causes marked increases in glucose and insulin levels and the GLP-1 peak.[12] Indeed the overshooting and delayed insulin output does not match the time course of the change in serum glucose level. Thus, the insulin level is decoupled and dyssynchronous from the glucose level.
In our patient, late dumping syndrome triggered by hyperinsulinemia was associated with overshooting of insulin output, which was delayed and did not match the time course of the change in serum glucose level. Thus, the insulin level was decoupled and dyssynchronous from the glucose level without treatment. After treatment with liraglutide, the patient's fasting insulin level decreased markedly.
We suggest that this glucose–insulin mismatch triggered by accelerated gastric emptying and larger and earlier increases in plasma glucose, GLP-1, and GIP concentrations is the cause of reactive hypoglycemia.[10] Abrahamsson et al[16] proposed a glucose-stabilizing mechanism to explain the positive effect of GLP-1 analogs. The outcome of the case study presented here is consistent with this proposal and suggests that the GLP-1 analog liraglutide used to treat this patient may have provided a stable concentration of GLP-1 and thus resolution of the mismatch. Abrahamsson et al also proposed that endogenous GLP-1 has a short window of activity, whereas exogenous GLP-1 analogs promote persistent GLP-1 receptor activation. This could explain the lower total insulin level after treatment with liraglutide and the resolution of symptoms.
Laferrère et al[21] studied the incretin effect after Roux-en-Y gastric bypass and reported decreases in fasting glucose levels from 7.95 ± 1.74 before gastric bypass to 6.42 ± 0.80 mmol/L after gastric bypass (P = 0.957), in peak glucose levels from 14.24 ± 3.23 before gastric bypass to 12.02 ± 1.39 mmol/L after gastric bypass (P = 0.514), and fasting insulin levels from 172 ± 69 before gastric bypass to 127 ± 51 pmol/L after gastric bypass (P = 0.195), but an increase in peak insulin levels from 492 ± 288 before gastric bypass to 769 ± 335 pmol/L after gastric bypass (P = 0.286).
The higher and mismatched peak insulin level may be one reason for postprandial hyperinsulinemic hypoglycemia. Treatment with liraglutide reduced the peak insulin level, which may explain the improvement in the symptoms of dumping syndrome experienced by our patient.
Finally, in our case report liraglutide had a dose-dependent effect on the insulin course. After liraglutide treatment, the insulin peak during the OGTT was lower, occurred sooner, and was matched more closely to the change in glucose level. This change in insulin release was probably directly related to the resolution of the patient's symptoms. Thus, exogenous GLP-1 analogs seem to synchronize the pancreatic insulin output and blood glucose level, and may even decrease insulin output.
In this patient, liraglutide was effective in treating hyperinsulinemic hypoglycemia associated with late dumping syndrome. The OGTT and CGM showed considerable effects of the drug on serum insulin level and on the glucose–insulin mismatches, which were probably triggered by accelerated gastric emptying and a larger and earlier increase in plasma glucose, GLP-1, and GIP concentrations. Daily use of the GLP-1 analog liraglutide caused this mismatch to disappear, and the matching effect occurred through the rapid decrease in the insulin level.
4 Conclusion
The analysis of our case study suggests a novel treatment approach to treat patients with late dumping syndrome that fail standard medical treatment. Additional studies are warranted to address the overall effect size and safety of GLP-1 analogs in treatment of late dumping syndrome.
Abbreviations: CGM = continuous glucose measurement, GERD = gastroesophageal reflux disease, GIP = gastric inhibitory polypeptide, GLP-1 = glucagon-like peptide-1, OGTT = oral glucose tolerance test.
Authors’ contribution: All authors performed substantial contributions to conception and design of the article and to acquisition, analysis and interpretation of data. All authors reviewed the manuscript for important intellectual content and approved the final version for publication.
Informed consent: Informed consent was obtained from the patient included in the study.
Ethical approval: All procedures performed in this study involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards.
The authors have no conflicts of interest to disclose.
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PMC005xxxxxx/PMC5371454.txt |
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Medicine (Baltimore)Medicine (Baltimore)MEDIMedicine0025-79741536-5964Wolters Kluwer Health 28328817MD-D-16-0659910.1097/MD.0000000000006349063494300Research ArticleObservational StudyRetrospective analysis of the overt proteinuria diabetic kidney disease in the treatment of modified Shenzhuo formula for 2 years Chen Hongdong MDaGuo Jing MDbZhao Xuemin MDcHe Xinhui MDcHe Zhongchen MDaZhao Linhua PhDd∗Tong Xiaolin PhDb∗Shao. Jiaqing a Department of Endocrinology, Guang’anmen Hospital of China, Academy of Chinese Medical Sciencesb Department of Endocrinology, Beijing Hepingli Hospitalc Graduate School, Beijing University of Chinese Medicined Molecular Biology Laboratory, Guang’anmen Hospital of China, Academy of Chinese Medical Sciences, Beijing, China.∗ Correspondence: Linhua Zhao, Molecular Biology Laboratory, Guang’anmen Hospital of China, Academy of Chinese Medical Sciences, Beijing, China; Xiaolin Tong, Department of Endocrinology, Guang’anmen Hospital of China, Academy of Chinese Medical Sciences, Beijing 100054, China (e-mails: melonzhao@163.com; xiaolintong_66@126.com).3 2017 24 3 2017 96 12 e63491 11 2016 12 2 2017 20 2 2017 Copyright © 2017 the Author(s). Published by Wolters Kluwer Health, Inc.2017This is an open access article distributed under the terms of the Creative Commons Attribution-Non Commercial-No Derivatives License 4.0 (CCBY-NC-ND), where it is permissible to download and share the work provided it is properly cited. The work cannot be changed in any way or used commercially without permission from the journal. http://creativecommons.org/licenses/by-nc-nd/4.0Abstract
The objective of the present study was to evaluate the 2-year effectiveness of modified Shenzhuo formula in the treatment of overt proteinuria diabetic kidney disease (DKD).
Patients diagnosed with type 2 DKD in the clinical research database of Prof Xiaolin Tong (>20,000 data points) with >1-year follow-up were screened for this study. Patients’ demographic data, chief complaint, present illness, past history, allergic history, personal history, family history, test results, tongue images, pulse information, and prescription information at 1, 1.5, and 2 years of follow-up were analyzed. EpiData3.1 was used to establish the electronic database of this research and SPSS v20.0 (SPSS Inc, Chicago, IL) was used for performing statistical analyses.
The patients’ common main symptoms of overt proteinuria DKD were weak breath and fatigue, numbness of limbs, insomnia, blurred vision, nocturia, edema, low backache, constipation, itchy skin ulcer, and chills. The average 24-hour urinary protein of patients treated with modified Shenzhuo formula was statistically significantly lower than baseline values at 1, 1.5, and 2 years (0.66 g, 95% confidence interval [CI] [−0.95, −0.41]; 1.00 g, 95% CI [−1.67, 0.38]; 1.11 g, 95% CI [−1.79, −0.57]). There are no statistically significant differences between the glomerular filtration rate at the baseline and that after modified Shenzhuo formula intervention. Statistically significant reductions in serum triglyceride and glycosylated hemoglobin values and systolic blood pressure also were recorded. Other indexes, including serum creatinine, blood urea nitrogen, diastolic blood pressure, cholesterol, high-density lipoprotein, and low-density lipoproteins, did not differ between baseline and post-treatment time points.
Modified Shenzhuo formula could reduce 24-hour urinary protein excretion in patients with DKD. The formula maybe had the potential advantages on glomerular filtration rate, creatinine reciprocal, blood lipid levels, etc.
Keywords
diabetic kidney diseasemodified Shenzhuo formulaovert proteinuriaretrospective analysisOPEN-ACCESSTRUE
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1 Introduction
Diabetic kidney disease (DKD) is a common chronic complication of diabetes. It usually is progressive, leading to end-stage renal disease, and ultimately to death. According to US Renal Data System, the end-stage renal disease caused by DKD accounts for about 44% of the total in the United States.[1] In Asian countries, the corresponding is about 40% of the total in Japan,[2] 48% in Korea,[3] and 19% in China, and the incidence of DKD in hospitalized diabetic patients has reached 34.7% in China.[4] Chronic, progressive DKD has become a serious threat to people's life and health.
At present, the prevention and treatment of DKD consists of 3 stages. The first is prevention. In persons with abnormal glucose tolerance, lifestyle modification is used to control blood sugar and prevent the development of diabetes and DKD. This measure includes diet, exercise, limited alcohol intake, smoking cessation, and weight control. The second is early treatment. Early treatment of DKD aims at reducing the frequency or delaying the occurrence of macroalbuminuria in patients who have microalbuminuria. Third, prevention or delay of progressive renal dysfunction, with renal transplant therapy, should be considered for the patients with renal failure.[5] However, the effectiveness of the treatment is less than satisfactory in clinic. It is very important to find an effective treatment to reduce the proteinuria for the patients with DKD.
It is reported that the emergency of overt proteinuria predicts the accelerating progression of DKD, so controlling and minimizing proteinuria has been the key point to delay the progression of DKD. Research conducted in recent years has shown advantages that treatment with Chinese medicines can reduce proteinuria and block the progress of DKD.[6–11] There are few high-quality randomized controlled trials conducted in recent years about overt proteinuria DKD treated by traditional Chinese medicine (TCM). It is difficult to conduct randomized controlled trials about overt proteinuria DKD for its clinical features. Li et al[12] achieved 1, and so did Jia et al.[13] But the observation period of most of these researches is ≤1 year. Thus, it was very difficult to evaluate whether a long-term intervention with TCM could have more benefits for the patients with overt proteinuria DKD.
By applying modified Shenzhuo formula for the treatment of overt proteinuria of DKD in the long-time clinical work according to the syndrome differentiation in the theory of the TCM combined with the pathological characteristics, Professor Xiaolin Tong has achieved an ideal curative effect.
This research aims to evaluate the long-term intervention effectiveness of modified Shenzhuo formula by analyzing the electronic records of DKD patients with overt proteinuria and to make our experience with the formula widely known to clinicians.
2 Methods
2.1 General data
This research is based on the “Xiaolin Tong Clinical Research Database,” which has been established for clinical studies in our institution and includes all of Professor Tong's medical records since 2009. The database is updated after every visit and managed by hospital data manager. The standardized data include demographic data, chief complaint, history of present illness, history of past illness, allergic history, personal history, family history, test indices, tongue images, pulse information, and prescriptions.
2.2 Inclusion and exclusion criteria
Inclusion criteria are as follows: the diagnosis of type 2 diabetes mellitus (T2DM), the diagnosis of overt proteinuria of DKD, and the follow-up period of >1 year with interval between visits ≤3 months and >4 visit times per year.
2.3 Exclusion criterion
Exclusion criterion is the following: qualitative measurement of urinary protein but not quantitative measurement.
2.4 Intervention
DKD patients’ levels of blood glucose, lipid, and blood pressure (BP) were stabilized by oral medications or insulin injections. All patients were administered a modified Shenzhuo formula (200 mL, bid). The medicines were provided by the Department of Pharmacy, Guang’anmen Hospital. Modified Shenzhuo formula was taken 30 minutes before or after breakfast and supper. Treatment lasted ≥1 year. Shenzhuo formula is an empirical compound TCM decoction of Prof Tong. It is composed of Huang Qi, Da Huang, Shui Zhi, Huang Lian, Zhi Mu, etc. There were associated herbs for the treatment of associated diseases, such as Huang Lian and Zhi Mu for high blood glucose; Gegen, Dilong, Yi Mu Cao, Gou Teng, and Tianma for hypertension; Hong Qu, Shan Zha, and Heye for hyperlipidemia; and Wei Ling Xian, Qinpi, and Bixie for hyperuricemia.
2.5 Measurements
The primary laboratory outcome measurement was 24-hour urinary protein excretion; the secondary outcome measurement was glomerular filtration rate (GFR); the observation measurements were 3 items of renal function (serum creatinine [SCR], blood urea nitrogen, and uric acid [UA]), blood lipids (cholesterol, triglyceride [TG], high-density lipoproteins, and low-density lipoproteins [LDLs]), BP, and glycosylated hemoglobin (HbA1c). These measurements were carried out in a central laboratory in Guang’anmen Hospital. The frequency of each symptom was calculated according to the inquiry information from the 69 visits, summing up the number of times each symptom appears in the 69 visits. Measurements for each patient were recorded at the first visit and 1, 1.5, and 2 years after the first visit. Expected glomerular filtration rate (eGFR) was calculated by Modification of Diet in Renal Disease formula. Adverse events were assessed using vital signs, clinical signs, and symptoms.
2.6 Data extraction and analysis
1. The first 24-hour urinary protein quantitation was taken at the baseline; 2 researchers separately extracted the 0-, 1-, 1.5-, and 2-year records information and filled in the case report forms. The records information included the demographic data, duration of disease, combined diseases, tongue, pulse, the main symptoms of interrogation, change of the main symptoms, test index, formula, dose, etc.
2. Using EpiData3.1 to establish the electronic database of this research, 2 researchers separately recorded data. The third researcher completed the double entry and validation. When the data were not consistent, the case report forms were assessed and errors corrected.
3. Statistical analyses were processed with SPSS v20.0 (SPSS Inc, Chicago, IL). Measurement data were the mean ± standard deviation ( ). The 95% confidence interval of mean value difference was used to compare baseline and after intervention change in the abovementioned characteristics. Fitting curve analysis was used to present and predict disease trends.
2.7 Study design figure
The study design figure is shown as Fig. 1.
Figure 1 Study design.
2.8 Ethical approval
The present study was a retrospective and small sample study based on the real-world clinical recorded data. It was not a prospective study, and the patients’ verbal consent was taken for providing their medical records for analysis and the results of the study. In this study, we have reported only the medical records and statistical results, not including the patients’ privacy information, so we think it did not touch on benefits and harms of patients and ethical approval and written patient consent was not necessary.
3 Results
3.1 General information
3.1.1 Demographic and disease duration characteristics
A total of 21 patients with 69 visits with overt proteinuria DKD were included between June 2009 and December 2015 from the Xiaolin Tong Clinical Research Database. All the 21 patients had been followed for >1 year, 13 for >1.5 years, and 11 for >2 years. The average age was 54.3 ± 12.8 years. The maximum age was 79 years and the minimum age was 34 years. The average duration of T2DM was 12 ± 5.5 years, the maximum duration was 22 years, and the minimum duration was 5 years. The average duration of DKD was 2.0 ± 1.5 years. The longest duration was 6 years and the shortest duration was 1 year.
3.2 Associated diseases
Diseases associated with DKD are listed in Table 1. As might be expected, the most common diseases were hypertension and hyperlipidemia.
Table 1 Associated diseases.
3.3 Main symptoms
3.3.1 Frequency of common symptoms
The patients’ 10 most common symptoms are listed in Table 2. The frequency of each symptom was calculated according to the inquiry information from the 69 visits, summing up the number of times each symptom appears in the 69 visits. Data of the top 10 symptoms were extracted and analyzed.
Table 2 Frequency of main symptoms.
3.4 Effectiveness of top 10 main symptoms
The judgment of effectiveness was based on the baseline. Compared to the baseline, it was recorded as “disappearance” if the symptom disappeared, “better” if there was relief, “no change” if the symptom was at the baseline or not changed significantly, and “worsen” if aggravated. The cure rate was calculated as disappearance frequency/total changed frequency; relief rate was calculated as better frequency/total changed frequency; no change rate was calculated as no changed frequency/total changed frequency; aggravated rate was calculated as worsened frequency/total changed frequency. Improvement rate was calculated as cure rate + relief rate. The results are recorded in Table 3.
Table 3 Effectiveness of main symptoms.
3.5 Test indices
The primary laboratory outcome was 24-hour urinary protein excretion. As illustrated in Table 4 and Fig. 2, protein excretion declined significantly from baseline to that at 1-, 1.5-, and 2-year time points. The secondary outcome was GFR. The data in Table 5 and Fig. 3 illustrate that the eGFR did not change significantly over the 2 years of follow-up.
Table 4 Twenty-four-hour urinary protein excretion quantitation.
Figure 2 Fit plot of 24-hour urinary protein quantitation. The figure includes data of 9 cases who were screened from the 21 cases whose 24-hour urinary protein quantitation value was fully recorded at baseline, 1, 1.5, and 2 years. GFR = glomerular filtration rate.
Table 5 eGFR.
Figure 3 Fit plot of eGFR. The figure includes data of 6 cases who were screened from the 21 cases whose eGFR value was fully recorded at baseline, 1, 1.5, and 2 years. eGFR = expected glomerular filtration rate.
The observation outcomes were 3 items of renal function (SCR, blood urea nitrogen, UA), 4 items of blood lipid (cholesterol, TG, high-density lipoprotein, LDL), BP, and HbA1c. The data are recorded in Table 6.
Table 6 Observed outcome measures.
3.6 Survival analysis—creatinine reciprocal curve (1/SCR)
The creatinine reciprocal curve was used to predict the prognosis trend of patients. As illustrated in Table 7 and Fig. 4, the slope of creatinine reciprocal curve increases with increased intervention time.
Table 7 Creatinine reciprocal.
Figure 4 Fit plot of creatinine reciprocal. SCR = serum creatinine.
3.7 Safety
The liver function and routine blood test of all the participants indicated no significant changes after intervention compared with baseline. No discomforts or severe adverse events were reported.
4 Discussion
The major finding of this study was that the 24-hour urinary protein excretion of patients with overt DKD proteinuria was significantly less after the intervention of modified Shenzhuo formula. Moreover, this salutary effect on protein excretion was achieved while a normal GFR was maintained. The study also found that after treatment with modified Shenzhuo formula, many of the patients’ main symptoms improved.
The key point in treating overt proteinuria in DKD is reducing the loss of urinary protein, which is still a medical problem. Studies have shown that urinary albumin to creatinine ratio of overt proteinuria of DKD increases 133% in 4 years[14]; thus, urinary protein excretion increases together with the progression of the disease.[15] Effective treatment for the proteinuria of DKD has not been developed. Thus, our finding that Shenzhuo formula seems to decrease the progression DKD, as measured with protein excretion, is a promising development.
The National Kidney Foundation Kidney Disease Outcomes Quality Initiative has divided chronic kidney disease into 5 stages based on GFR: stage 1, eGFR ≥90 mL/(min 1.73 m2); stage 2, eGFR 60 to 89 mL/(min 1.73 m2); stage 3, eGFR 30 to 59 mL/(min 1.73 m2), stage 4, eGFR 15 to 29 mL/(min 1.73 m2); and stage 5, eGFR <15 mL/(min 1.73 m2).[14] Once overt proteinuria is present, there is a progressive reduction in GFR, rate varying widely from patient to patient, with an average decline of approximately 10 mL/(min 1.73 m2) per year in untreated subjects,[16] and depending on control of promotors of progression such as hypertension and degree of albuminuria and on individual response to treatment, this period is characterized by gradual deterioration of GFR in a linear fashion at a variable rate (average 4.5 mL/[min 1.73 m2] per year).[17] Our finding that, after the intervention with modified Shenzhuo formula, the GFR did not decline significantly from baseline values may be evidence that this TCM maybe could slow the progressive decline in eGFR and the associated deterioration of renal function.
In this study, the main symptoms of DKD with overt proteinuria were shortness of breath and fatigue, numbness of limbs, insomnia, blurred vision, nocturia, edema, low back pain, constipation, itch or ulcer of skin, and chills. Shortness of breath and fatigue, edema, nocturia, and constipation were well improved. However, not all symptoms improved: blurred vision improved in 66% of patients but worsened in 33%, so was the numbness of limbs; this incomplete response may reflect the reality that diabetic retinopathy often is progressive and has no effective drug treatment. Professor Xiaolin Tong proposes that the core pathogenesis for the symptoms of DKD patients is deficiency of kidney qi and blood stasis of kidney collaterals. The consequences of deficiency of kidney qi are shortness of breath, lack of desire to speak, and fatigue, with shortness of breath and fatigue being the most common. DKD patients with overt proteinuria always have diabetic retinopathy. Since both DKD and diabetic retinopathy are microvascular diseases, they often coexist and are parallel in development; thus, DKD patients often report that they have blurred vision.[18–20] Numbness of the limbs also is a common symptom of long-standing diabetes because of impaired peripheral nerve function. Constipation, loose stools, or alternating constipation and loose stools is a common complaint among diabetics, which is ascribed to impaired gastrointestinal autonomic nerve function.[21,22] The symptom of nocturia is common when long-standing disease leads to impaired kidney collateral and renal tubular dysfunction. Long-standing disease also leads to more deficiency of qi and dysfunction of qi in San Jiao, with accumulation of fluid, or edema.
In this study, the average duration of T2DM was 12.5 years after DKD was recognized. Studies have reported that about 73% of patients with >10 years of T2DM have kidney disease.[23] Thus, these patients must be observed for the possibility of developing DKD. According to Kidney Disease Outcomes Quality Initiative, patients with T2DM should be screened for urinary protein in order to permit early diagnosis and treatment of DKD.[14] This study found that hypertension, hyperlipidemia, fatty liver, hyperuricemia, and coronary artery disease were commonly associated with DKD. Thus, these metabolic disorders are risk factors for DKD,[24–27] and should be comprehensively monitored and treated. The results of the current study show that the modified Shenzhuo formula can lower BP and blood UA, glucose, and lipid concentrations, which may delay the development of DKD.
The various components of modified Shenzhuo formula have various biological effects. Sheng Huang Qi (raw astragalus) can boost qi to secure and strict, disinhibit water, and disperse swelling. Da Huang (rhubarb) has the effect of expelling stasis to free the channels, free the bowels, and discharge turbidity. Shui Zhi (leech) is usually used to supply vacuity and strong body having an advantage that it dispels static blood but does not affect new blood. Dan Shen (Salvia) supplies blood and quickens the blood. A combination of the 4 herbs boosts qi and quickens the blood. Studies have reported that total flavonoids of Astragalus, total polysaccharides of Astragalus, and total saponins of Astragalus from Sheng Huang Qi (raw astragalus) can improve the clearance of antigen and promote the repair of glomerular basement membrane. Selenium element in Sheng Huang Qi (raw astragalus) can protect the charge barrier and mechanical barrier of the basement membrane, thus reducing the permeability of urine protein.[28,29]Da Huang (rhubarb) can clean the bowel and relieve the body, which leads to a part of nonprotein nitrogen discharged from intestine; it also restrains the hyperplasia of mesangial cells and renal tubular epithelial cells, thus reducing the compensatory hypertrophy. At the same time, the high coagulation rate and the precarious state of renal failure patients can be improved, with increasing renal blood flow, protecting residual renal function, reducing the occurrence of proteinuria, and delaying the progression of DKD.[30]Shui Zhi (leech) contains 17 kinds of amino acids, including 8 kinds of essential amino acids and 14 kinds of elements such as Zn, Mn, Fe, Co, Cr, Se, Mo, and Ni.[31] Gu et al[32] reported that Shui Zhi (leech) can ameliorate early kidney hyperdynamic abnormality and protect the kidney of DKD rats by a mechanism that may be associated partly with a downregulation of levels and expression of endothelin-1. Dan Shen (Salvia) contains danshensu, labiatenic acid, tanshinone IIa, salvianolic acid A, and other ingredients.[31] Studies have found that Dan Shen (Salvia) can lower blood lipids, reduce blood viscosity, dilate blood vessels, inhibit platelet aggregation and nuclear release, have an antithrombotic effect, improve microcirculation, and repair injured vascular endothelial cells. These effects can improve kidney blood flow, protect kidney function, and promote the recovery of kidney function.[32]
Effects on blood lipid, BP, blood sugar, and serum UA can reflect the advantage of individualized treatment and comprehensive regulation TCMs offer. Blood lipid, BP, blood sugar, and serum UA are risk factors for the occurrence and development of DKD. Hypertension can accelerate the progression of the proteinuria of DKD patients and the deterioration of renal function.[33,34] Blood lipid disorders can accelerate blood vessel damage and the procession of DKD. High blood sugar, making the proteins of glomerular basement membrane structural nonenzymatic glycation, will cause the basement membrane barrier defects, resulting in urinary protein to renal damage. According to the Diabetic Nephropathy Prevention Expert Consensus of 2014, the BP target of patients with DKD is 130/80 mm Hg, LDL levels <2.6 mmol/L (<1.86 mmol/L if combined with coronary heart disease), TG <1.5 mmol/L, and Hb A1c value ≤7%. For elderly patients, HbA1c value of 7% to 9% may be allowed.[5] Thus, the key to delay the progression of DKD lies in the comprehensive strict regulation and control. According to individual disease differences, the Shenzhuo formula can be modified to provide accurate treatment for various combined diseases. Huang Lian (Coptis chinensis), Zhi Mu (Anemarrhenae), etc., are associated with Shenzhuo formula for the treatment of high blood glucose; Gegen (Pueraria), Dilong (Pberetima), Yi Mu Cao (motherwort), Gou Teng (rhynchophylla), Tianma (Rhizoma gastrodiae), etc., for hypertension; Hong Qu (red rice) for hyperlipidemia; and Wei Ling Xian (Radix clematidis), Qinpi (fraxini), and Bixie (Rhizoma Dioscoreae hypoglaucae) for hyperuricemia. The addition and subtraction of medications is based not only on the syndrome differentiation theory but also on the >30-year clinic experience of Professor Xiaolin Tong.
5 Limitations
Our study was just a retrospective, small-sample, single-center trial, and has many limitations: first, it is a retrospective study based on real-world data, with the inherent potential for bias and omission of important data. Second, the study is not strictly controlled for therapeutic measures or lifestyle modification that, in addition to modified Shenzhuo formula, might have affected patients’ clinical course. Third, the study is not controlled for comparison of patients who received the modified Shenzhuo formula with those who did not. These limitations highlight the need for rigorously controlled, prospective studies of the effects of the modified Shenzhuo formula in the management of DKD. In fact, we are conducting a double-blind, double-simulation, randomized control trial of Shenzhuo formula in the overt proteinuria stage of DKD. The research, which has been registered in the Chinese Clinical Trial Registry, will test the validity and feasibility of using a TCM as an alternative in the treatment of DKD.
Modern medicine advocates the following 5 kinds of preventive and therapeutic measures for DKD: lifestyle modification, control of blood glucose, control of BP, correction of disorders of lipid metabolism, and renal replacement therapy. High-quality studies have shown that strict control of blood glucose, BP, and blood lipids can prevent the emergence of microproteinuria and delay the deterioration of renal function,[35–41] but there is no conclusive evidence that any of these measures significantly reduces the amount of proteinuria in patients with DKD. In the quest for new preventive and treatment measures for DKD, we feel that traditional Chinese medications should be considered. The traditional medications have a rich, 1000-year history in the treatment of diabetes mellitus and DKD and therefore form the basis for future research. The results of this study suggest that Shenzhuo formula, through its effects on blood sugar, BP, and serum lipids, can reduce 24-hour urinary protein excretion, delay the deterioration of renal function, and improve the main symptoms of patients over a long time period. TCM has the potential advantage of targeting multiple facets of the disease and comprehensively improving patients’ symptoms and quality of life.[42–46]
6 Conclusions
Modified Shenzhuo formula could reduce 24-hour urinary protein excretion in patients with DKD. The formula maybe had the potential advantages on GFR, creatinine reciprocal, blood lipid levels, etc.
Abbreviations: BP = blood pressure, DKD = diabetic kidney disease, GFR = glomerular filtration rate, HbA1c = glycosylated hemoglobin, LDL = low-density lipoprotein, SCR = serum creatinine, TCM = traditional Chinese medicine, TG = triglyceride, UA = uric acid.
HC and JG contributed equally to this study as first authors.
LZ and XT proposed the paper topic; HC and JG finished the study and wrote the paper; XZ, XH, and ZH helped to extract and manage the data; and LZ revised the paper.
This study is supported by the Fundamental Research Funds for the Central Public Welfare Research Institutes (no. zz0808004), the Traditional Chinese Medicine Science and Technology Research Projects of State Administration of Traditional Chinese Medicine (2016ZX03), and the Major Program of the National Natural Science Foundation of China (grant no. 81430097).
The authors have no conflicts of interest to disclose.
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Medicine (Baltimore)Medicine (Baltimore)MEDIMedicine0025-79741536-5964Wolters Kluwer Health 28328818MD-D-16-0540510.1097/MD.0000000000006350063504500Research ArticleQuality Improvement StudyThe distal classification and management of choledochal cyst in adults Based on the relation between cyst and pancreatic ductLiu Yanfeng MD, PhDaSun Jingxian MDbGuo Sen MDaLiu Zengli MDaZhu Min MD, PhDa∗Zhang Zong-li MD, PhDa∗Merrett. Neil a Department of Hepatobiliary Surgery, Qilu Hospital of Shandong Universityb Department of Surgery, Affiliated Hospital of Shandong University of Traditional Chinese Medicine, Jinan, Shandong, China.∗ Correspondence: Zong-li Zhang, Department of Hepatobiliary Surgery, Qilu Hospital of Shandong University, 107 Wenhua Xi Road, Jinan 250012, Shandong, China (e-mail: zhang_zongli@126.com); Min Zhu, Department of Hepatobiliary Surgery, Qilu Hospital of Shandong University, 107 Wenhua Xi Road, Jinan 250012, Shandong, China (e-mail: zhu__min@126.com).3 2017 24 3 2017 96 12 e635025 8 2016 18 2 2017 20 2 2017 Copyright © 2017 the Author(s). Published by Wolters Kluwer Health, Inc.2017This is an open access article distributed under the terms of the Creative Commons Attribution-Non Commercial License 4.0 (CCBY-NC), where it is permissible to download, share, remix, transform, and buildup the work provided it is properly cited. The work cannot be used commercially without permission from the journal. http://creativecommons.org/licenses/by-nc/4.0Abstract
Todani classification is extensively used to guide the surgical strategy of choledochal cysts, but no systematic investigations on the distal management of intrapancreatic choledochal cysts have been conducted. This study reports the distal classification and management of choledochal cysts in adults based on the relation between the cyst and pancreatic duct. Patients with choledochal cyst who underwent operation, including distal management, in our department from January 2009 to December 2014 were retrospectively reviewed. Patients presenting symptoms, coexisting diseases, surgical treatment, perioperative complications, and long-term follow-up according to the distal classification of choledochal cyst were analyzed. A total of 54 patients with choledochal cyst were included in the present retrospective study. Based on the distal classification of choledochal cyst, 39 patients (72.22%) were type 1, 13 patients (24.07%) were type 2, and 2 patients (3.70%) were type 3. Thirty-nine type 1 patients and 10 type 2 patients underwent excision of intrapancreatic choledochal cyst or bile duct. Three type 2 patients received excision of distal cylindrical cyst and papilla, followed by pancreatic duct plasty with duodenum mucosa. One type 3 patient underwent endoscopic sphincteroplasty, and another type 3 patient underwent transduodenal sphincteroplasty. After the operation, 11 patients (20.37%, 11/54) had short-term perioperative complications. The long-term follow-up results showed that the satisfactory rate (excellent and good outcomes) was 95.83%. Current distal classification of choledochal cysts could provide a more targeted strategy for complete excision to eliminate potential dead space within the pancreas, protect the pancreatic duct, and prevent reoperation.
Keywords
choledochal cystdistal classificationpancreatic ductsurgical managementOPEN-ACCESSTRUE
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1 Introduction
Choledochal cysts are characterized by varying degrees of congenital dilatation of the biliary system including the intrahepatic and extrahepatic duct, with an incidence of 1 in 100,000 to 150,000 individuals in Western populations and approximately 1 in 13,000 individuals in Asian populations.[1] Presence of an anomalous junction of the pancreaticobiliary duct that allows pancreatic secretions to reflux into the biliary tree is the generally accepted etiopathogenic theory of these cysts.[2,3] Nearly 20% of choledochal cysts are present in adults, and malignant transformation is the most feared complication.[4] A 6% to 30% risk of developing malignancy is estimated in patients with choledochal cysts; the risk is low in childhood (<1%) but increases to about 30% to 40% with age greater than 50 years.[5,6]
Currently, to avoid complications from remnant cyst excision and reoperation, the best surgical strategy is to excise the cyst areas completely (including gallbladder) with hepaticojejunostomy. Surgical treatment depends on the anatomic findings and extent of biliary involvement according to the widely used Todani classification.[7] Complete cyst excision includes proximal and distal excision. Complete cyst excision to the normal proximal bile duct is the standard procedure, which is accompanied with additional hepatectomy if necessary. As the cyst extends into the pancreas, its management is also crucial and sometimes difficult. Injury to the pancreatic duct and surrounding tissues may cause serious complications, such as recurrent pancreatitis, bleeding, stone formation, and carcinoma.[8] Furthermore, remnant intrapancreatic choledochal cysts may give rise to subsequent malignant transformation with an estimated risk of 0.7% to 6%.[9]
To date, no systematic investigations have been conducted on the distal management of intrapancreatic choledochal cysts. Based on the above situation and our surgical experience, we propose the following classification concerning the distal management of choledochal cysts (Fig. 1): type 1, no relation between choledochal cyst and pancreatic duct; type 2, close relation between the twos; and type 3, accordance with type III of Todani classification. Thus, this study aimed to report our experience with the distal management of choledochal cysts using our classification.
Figure 1 The current distal classification of choledochal cysts: type 1, no relation between choledochal cyst and pancreatic duct; type 2, close relation between the above twos; type 2 special subtype, the pancreatic duct converges with the cylindrical cyst; type 3, accordance with type III of Todani classification.
2 Materials and methods
2.1 Patients
From January 2009 to December 2014, the medical records of adult patients (aged ≥16 years) with choledochal cysts at the Department of Hepatobiliary Surgery, Qilu Hospital of Shandong University, were reviewed retrospectively. Clinical characteristics assessed included patient demographic information, presenting symptoms, surgical treatments, pathological results, perioperative complications, and long-term outcomes. The choledochal cyst was diagnosed by radiologic imaging including computed tomography, magnetic resonance cholangiopancreatography, and ultrasonography. Diagnosis without malignant transformation was confirmed by histopathologic findings. Todani types II and V were not included in our study profile because the present study only focused on the distal management of choledochal cysts. The patients were classified into 3 types according to the current distal classification. The study protocol was approved by the Ethics Committee of Qilu Hospital of Shandong University.
2.2 Surgical management
Given that incomplete cyst excision can lead to recurrent symptoms and malignant transformation within the remnant cyst, current surgery includes the excision of the entire cyst (including gallbladder) and restoration of biliary-enteric continuity.[10] The proximal extent should be identified and evaluated before resection. For Todani type IVa with extrahepatic and intrahepatic cysts, the extrahepatic cyst should be firmly excised; if the intrahepatic cyst is limited, partial hepatectomy with biliary-enteric reconstruction can be performed.
The distal management of choledochal cysts was performed according to our distal classification. For type 1 with no relation between choledochal cyst and pancreatic duct based on preoperative imaging, the distal cyst or seemingly normal bile duct was excised to about 5 mm from the convergence with the pancreatic duct and the stump was sutured.[11] For type 2, the same management principle as type 1 was adopted. Occasionally, a special subtype of type 2 with cylindrical cyst and insufficiency of Vater papilla can occur. The distal end of the choledochal cyst directly enters the duodenum with insufficiency of Vater papilla, and the pancreatic duct looks like an attachment that converges with the large cyst. In this situation, the distal cylindrical cyst and papilla are excised, followed by pancreatic duct plasty with duodenum mucosa, which is modified from local resection of benign neoplasm and early noninvasive adenocarcinoma in papilla.[12,13] In consideration of the low malignant rate in type 3 cysts, unroofing (endoscopic or transduodenal sphincteroplasty) or transduodenal excision (larger cysts) is optimal for choledochoceles.[1,14]
2.3 Assessment of postoperative complications and surgical outcomes
The Clavien–Dindo classification is applied to evaluate postoperative complications and consists of 7 grades (I, II, IIIa, IIIb, IVa, IVb, and V); this classification is valid and applicable worldwide in many fields of surgery.[15] In general, each complication has a corresponding grade, and the final grade of complications is adopted the highest. The patient's surgical outcome was assessed subjectively as excellent (no symptoms, attributable to the biliary tract injury or reconstruction), good (mild symptoms, not requiring invasive investigation or treatment), or failure (ongoing symptoms or stricture recurrence, requiring an invasive investigational or therapeutic procedure). Patients classified as either excellent or good were considered successful treatment.[16]
3 Results
A total of 54 patients with choledochal cyst were included in the present retrospective study. The mean patient age at diagnosis was 36.46 ± 12.44 years (range, 16–71 years). Thirty-two (59.26%) patients were in the range of aged 30 to 49 years. The presenting symptoms and coexisting diseases were shown in Table 1.
Table 1 The characteristics of patients with choledochal cysts in present study.
3.1 Classification based on the Todani and distal classification of choledochal cyst
According to the Todani classification of choledochal cyst, 37 patients (68.52%) were type I, 2 patients (3.70%) were type III, and 15 patients (27.78%) were type IVa. Meanwhile, based on the distal classification of choledochal cyst, 39 patients (72.22%) were type 1, 13 patients (24.07%) were type 2, and 2 patients (3.70%) were type 3. Among the Todani type I patients, 29 patients were type 1 and 8 were type 2 (Table 2).
Table 2 The patient classification based on the Todani and distal classification of choledochal cyst.
3.2 Surgical treatments
All the patients underwent surgical procedures with cyst excision and bilioenteric anastomosis. Among them, 43 patients (79.63%) underwent extrahepatic cyst excision (including cholecystectomy) and hepaticojejunostomy, 9 patients (16.67%) received extrahepatic cyst excision (including cholecystectomy), partial hepatectomy, and hepaticojejunostomy (Fig. 2D and E). Two Todani type III or type 3 patients underwent endoscopic and transduodenal sphincteroplasty (Fig. 2F–H).
Figure 2 The typical cases in present study. Case 1: (A) shows intrapancreatic choledochal cyst with infection and stone formation in it. Case 2: a special type 2 cyst with cylindrical cyst in operation (B) and papilla insufficiency of Vater demonstrated by intraoperative choledochoscope (C). Case 3: a patient with type IV a choledochal cyst with left hepatatrophy, choledocholithiasis (D) and intrahepatic biliary stone and dilatation (E). Case 4: a patient with type 3 (choledochocele) cyst (F) was performed with transduodenal sphincteroplasty. A metal probe was used to explore the cyst through duodenal papilla (G) and a temporary urinary catheter was applied as a support for sphincteroplasty (H).
For distal management, 39 type 1 patients and 10 type 2 patients underwent excision of the distal cyst or seemingly normal bile duct to about 5 mm from the convergence with the pancreatic duct, that is, the intrapancreatic cyst or bile duct (Fig. 2A). Three patients received excision of both distal cylindrical cyst and papilla, followed by pancreatic duct plasty with duodenum mucosa (Fig. 2B and C).
3.3 Perioperative complications and long-term follow-up
After operation, 11 patients (20.37%, 11/54) had short-term perioperative complications. Followed by the Clavien–Dindo classification, 6 patients presented with grade I complications (3 patients with pancreatic leak, 2 with abdominal infection, and 1 with delayed wound healing) and 5 patients exhibited grade II complications (2 patients with pancreatic leak, 2 with intestinal obstruction, and 1 with delayed wound healing). The last follow-up time was July 31, 2016, and the complete follow-up rate was 88.89% (48/54) with a mean follow-up of 49.69 months (range, 19–90 months). Using the surgical outcome criteria, 31 patients (31/48, 64.58%) were excellent, 15 patients (15/48, 31.25%) were good, and 2 patients (2/54, 4.17%) were fair outcomes. The satisfactory rate (excellent and good outcomes) was 95.83%. No patients were found with malignant transformation during the follow-up period.
4 Discussion
The concept of complete cyst excision is accepted by surgeons. Proximal cyst excision is a relative programatic procedure with caution to protect the portal vein and hepatic artery. For distal management, the cyst extends into the pancreas, and excision may be difficult because of surrounding adhesion to pancreatic tissue and portal vein during recurrent episodes of cholangitis. Based on these, surgeons may not perform complete excision in certain circumstances because of the risk of postoperative pancreatic leakage, bleeding, and peritoneal infection.[17–19] However, the unresected intrapancreatic choledochal cyst will result in the formation of a dead space within the pancreas. Pancreatic secretions will be forced into this space due to the presence of the anomalous pancreatobiliary junction.[2] Backflow of intestinal secretions results in the activation of pancreatic enzymes in the remnant cyst, which may lead to infection, stone formation, and an increased risk of malignancy.[20] A previous study demonstrated that no patients developed cholangiocarcinoma after complete cyst excision.[5] Thus, complete excision distal of the intrapancreatic cyst is suitable for eliminating dead space and subsequent complications, but the pancreatic duct must be treated with great care.
In this study, the distal management of intrapancreatic choledochal cysts is expounded in detail given that no systematic investigations have been reported. The Todani classification system, modified from the Alonso–Lej classification, is now widely adopted for choledochal cysts, and the clinical treatment strategies are also determined according to this classification system.[7,21] Five types are included in its classification: type I, a solitary extrahepatic cyst; type II, an extrahepatic supraduodenal diverticulum; type III (choledochocele), an intraduodenal cyst; type IV, extrahepatic and/or intrahepatic cysts; and type V (Caroli disease), multiple intrahepatic cysts. Although the 5 types summarize the possible morphologies with important instruction for surgical approach, the distal situation of choledochal cysts still needs to be elucidated. Concerning this situation, the classification only aimed at the correlation between intrapancreatic bile and pancreatic duct. In this classification, since irrelevant with pancreatic duct, Todani types II and V are excluded from the present study and classification.
To eliminate potential dead space within the pancreas, protect the pancreatic duct, and maintain unobstructed flow of pancreatic fluid, the current classification of distal intrapancreatic choledochal cysts can function as a highly targeted strategy for the following surgical approach with different types. Given the presence of the anomalous pancreatobiliary junction, the reflux of duodenal juice, and the erosion of activated pancreatic enzymes, cholangitis is common in patients with remnant cysts and may develop in the progression of choledochal cyst.[11] Recurrent episodes of infection may cause further damage to the dysfunction and stenosis of duodenal papilla, resulting in recurrent pancreatitis and cholangitis.[17,20] Thus, in type 1 classification, which has no obvious relation to pancreatic duct, the intrapancreatic cyst or the seemingly normal bile duct is excised and the stump is sutured. The pathological changes in choledochal cysts from inflammatory bile duct are difficult to differentiate, and the excision range of distal cysts mainly depends on radiology and intraoperative finding. To prevent cyst recurrence, cancer of postoperative residual bile duct, and reoperation occurrence, the excision range is rational and appropriate but slightly radical. In the present study, 39 type 1 patients and 10 type 2 patients underwent such kind of surgery with careful operation to prevent the bleeding of pancreatic tissues and protect pancreatic duct. All the patients unevenly passed through the perioperative period, and the long-term effects were satisfactory, except for 2 patients with recurrent cholangitis.
For type 2 classification, the same management principal with type 1 is adopted since eliminating the dead space and keeping the pancreatic fluids flowing into the duodenum. Nevertheless, the surgical management of special subtypes of type 2 with cylindrical cyst and papilla insufficiency of Vater differs. In this retrospective study, only 3 patients received this surgical procedure with the excision of cyst and papilla, followed by pancreatic duct plasty with duodenum mucosa. The long-term follow-up results showed that pancreatic exocrine function did not result in injury. Even so, more cases and experience need to be accumulated in the following study. Type 3 choledochal cysts (choledochoceles) can be treated by endoscopic sphincterotomy, sphincteroplasty alone, sphincteroplasty with cyst excision, or pancreaticoduodenectomy. Considering the low malignant rate in type 3 cysts, unroofing (endoscopic or transduodenal sphincteroplasty) or transduodenal excision (larger cysts) is optimal for choledochoceles.[1,14] In the study, 1 patient received endoscopic sphincteroplasty, and another received transduodenal sphincteroplasty. This finding showed that the endoscopic approach may be a better choice with minimal trauma. In the near future, more patients with choledochal cyst should be enrolled to strengthen our present study.
This study had several limitations. Owing to a respective study, selection and information bias exist, and this may lead to less-strong evidence. In addition, the study sample size is relatively small, and the operations were performed in 1 center. Further cases and collaboration with other centers are necessary for further studies.
In conclusion, the current classification of distal intrapancreatic choledochal cysts could provide a more targeted strategy for complete excision to eliminate potential dead space within the pancreas, protect the pancreatic duct, ensure unobstructed flow of pancreatic fluid, and prevent reoperation.
Abbreviations: CT = computed tomography, MRCP = magnetic resonance cholangiopancreatography.
Funding/support: The research was supported by Shandong Provincial Natural Science Foundation of China (no. 2015ZRE2760).
The authors have no conflicts of interest to disclose.
==== Refs
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Medicine (Baltimore)Medicine (Baltimore)MEDIMedicine0025-79741536-5964Wolters Kluwer Health 28328820MD-D-16-0132510.1097/MD.0000000000006362063627100Research ArticleObservational StudyLong-term outcomes of surgery alone versus surgery following preoperative chemoradiotherapy for early T3 rectal cancer A propensity score analysisCho Seung Hyun MD, PhDaChoi Gyu-Seog MD, PhDb∗Kim Gab Chul MD, PhDaSeo An Na MD, PhDcKim Hye Jung MD, PhDaKim Won Hwa MD, PhDaShin Kyung-Min MDaLee So Mi MDaRyeom Hunkyu MD, PhDaKim See Hyung MD, PhDdKantarçeken. Bülent a Department of Radiologyb Colorectal Cancer Centerc Department of Pathology, Kyungpook National University Medical Center, School of Medicine, Kyungpook National Universityd Department of Radiology, Dongsan Hospital, College of Medicine, Keimyung University, Daegu, Republic of Korea.∗ Correspondence: Gyu-Seog Choi, Colorectal Cancer Center, Kyungpook National University Medical Center, 807 Hoguk-ro, Buk-gu, Daegu 41404, Republic of Korea (e-mail: kyuschoi@mail.knu.ac.kr).3 2017 24 3 2017 96 12 e636225 2 2016 9 10 2016 17 2 2017 Copyright © 2017 the Author(s). Published by Wolters Kluwer Health, Inc.2017This is an open access article distributed under the terms of the Creative Commons Attribution-Non Commercial License 4.0 (CCBY-NC), where it is permissible to download, share, remix, transform, and buildup the work provided it is properly cited. The work cannot be used commercially without permission from the journal. http://creativecommons.org/licenses/by-nc/4.0Supplemental Digital Content is available in the text
Abstract
Recently, a few studies have raised the question of whether preoperative chemoradiotherapy (PCRT) is essential for all T3 rectal cancers. This case-matched study aimed to compare the long-term outcomes of surgery alone with those of PCRT + surgery for magnetic resonance imaging (MRI)-assessed T3ab (extramural depth of invasion ≤5 mm) and absent mesorectal fascia invasion (clear MRF) in mid/lower rectal cancer patients.
From January 2006 to November 2012, 203 patients who underwent curative surgery alone (n = 118) or PCRT + surgery (n = 85) were enrolled in this retrospective study. A 1:1 propensity score-matched analysis was performed to eliminate the inherent bias. Case-matching covariates included age, sex, body mass index, histologic grade, carcinoembryonic antigen, operation method, follow-up period, tumor height, and status of lymph node metastasis. The end-points were the 5-year local recurrence (LR) rate and disease-free-survival (DFS).
After propensity score matching, 140 patients in 70 pairs were included. Neither the 5-year LR rate nor the DFS was significantly different between the 2 groups (the 5-year LR rate, P = 0.93; the 5-year DFS, P = 0.94). The 5-year LR rate of the surgery alone was 2% (95% confidence interval [CI] 0.2%–10.9%) versus 2% (95% CI 0.2%–10.1%) in the PCRT + surgery group. The 5-year DFS of the surgery alone was 87% (95% CI 74.6%–93.7%) versus 88% (95% CI 77.8%–93.9%) in the PCRT + surgery group.
In patients with MRI-assessed T3ab and clear MRF mid/lower rectal cancer, the long-term outcomes of surgery alone were comparable with those of the PCRT + surgery. The suggested MRI-assessed T3ab and clear MRF can be used as a highly selective indication of surgery alone in mid/lower T3 rectal cancer. Additionally, in those patients, surgery alone can be tailored to the clinical situation.
Keywords
chemoradiotherapyMRIprognosisrectal cancerrectumOPEN-ACCESSTRUE
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1 Introduction
Preoperative chemoradiotherapy (PCRT) and subsequent surgery have been recommended for locally advanced rectal cancer (LARC) because of difficult surgical techniques and the anatomical position of the rectum in the narrow pelvic cavity. Although indications and methods for PCRT differ by country, the most widely accepted indication, which is the National Comprehensive Cancer Network (NCCN) guideline, is stage II or III rectal cancer.[1–5] However, this indication has become an issue in terms of the broad range of prognoses for T3 cancer.[6–13] Some of the latest studies have demonstrated that surgery alone achieved local recurrence (LR) rates ≤3% in highly selected T3 patients.[14,15] These findings have raised the question of whether PCRT is essential for all T3 cancers and whether the T3 subgroup can be treated by primarily surgery.
Recently, a few studies have tried to define a favorable T3 cancer for the potential indication of surgery alone. A few researchers have suggested that as a clear circumferential resection margin (CRM), N0/N1 or T3N0 according to the concordance of the histopathologic findings.[11,15] However, given that MRI is currently playing an important role in determining therapeutic planning, MRI-based indication of surgery alone in T3 rectal cancer will be better at defining T3 cancers that may respond to surgery alone.[6] Our hypothesis is that a combination of MRI-assessed T3ab with extramural depth of invasion ≤5 mm and absent mesorectal fascia invasion (clear MRF) can be used as a highly selective indication of surgery alone in mid/lower T3 rectal cancer.[16] To the best of our knowledge, there was no available research comparing oncologic outcomes between the 2 treatment arms based on this hypothesis. Therefore, the purpose of our study was to compare the long-term outcomes of surgery alone with those of surgery following PCRT (PCRT + surgery) for MRI-assessed T3ab and clear MRF in mid/lower rectal cancer patients.
2 Methods
This retrospective, single-institution study was approved by the local institutional review board, which waived informed consent.
2.1 Study Cohort
We searched our institutional database to identify patients who underwent rectal MRI between January 2006 and November 2012. A total of 1168 consecutive patients were found in the picture archiving and communication system database. We included 213 patients who satisfied the following criteria: had undergone pretherapeutic rectal MRI for adenocarcinoma staging; had tumors in the mid/lower rectum (≤10 cm from the anal verge); had staged MRI-assessed T3ab and clear MRF (in lower third cancer, a tumor >1 mm away from the levator ani muscle or no invasion into the intersphincteric plane was considered a clear MRF);[17] and had undergone curative surgery alone or PCRT + surgery at our institution. Among these patients, 10 patients were excluded for the following reasons: undergone transanal local excision (n = 3); diagnosed with synchronous or metachronous cancers (n = 3); determined to have stage IV cancer at initial staging (n = 3); and diagnosed with familial adenomatous polyposis (n = 1). Finally, 203 patients who met the eligibility criteria were enrolled as the study cohort (Fig. 1).
Figure 1 Flow diagram of the study cohort enrollment. AV = anal verge, BMI = body mass index, CEA = carcinoembryonic antigen, F/U = follow-up, LN = lymph node, MRF = mesorectal fascia, OP = operation, PCRT = preoperative chemoradiotherapy, Tx = treatment.
2.2 Treatment
All surgeries were performed or supervised by 3 experienced colorectal surgeons in the Division of Colorectal Cancer Center, Kyungpook National University Hospital. PCRT consisted of radiation therapy (RT) (4500–5000 cGy/25 fractions) concurrent with the “Mayo Regimen” chemotherapy.[18] Surgery with curative intent was performed 6 to 8 weeks (mean day, 60.4 ± 9.9 days; range 38–80 days) after the completion of PCRT. In our institution, during the late period of the study, PCRT was a routine treatment strategy for LARC; however, in some patients, our institution preferred primary surgery alone for early stage T3 cancer. Selective PCRT was provided for advanced or lower rectal cancer that was lymph node-positive (LN+). In histopathologic stage II or III patients who underwent surgery alone, adjuvant chemotherapy was selectively given with oral 5-fluorouracil (5-FU) and LF (leucovorin and 5-FU), respectively. According to the “Mayo Regimen,” LF-based adjuvant chemotherapy was also provided in patients who underwent PCRT + surgery. Since 2011, a multidisciplinary team approach has been established in our institution.
2.3 Outcome Variables
Histopathologic outcomes were recorded, which included the longitudinal tumor size, length of proximal resection margin (PRM), distal resection margin (DRM), the presence or absence of CRM invasion, lymphovascular invasion (LVI), perineural invasion (PNI), number of retrieved LN, LN stage, and the tumor stage according to the American Joint Committee on Cancer 7th edition.[19] All histopathologic outcomes were evaluated according to the guideline of the College of American Pathologists. The histopathologic tumor regression grade (TRG) was also recorded on the basis of that by Dworak et al.[20] The histopathologic TRG was graded as follows: grade 0 indicates the presence of viable tumor without any regressed change; grade 1, the presence of dominant tumor with apparent fibrosis and/or vasculopathy; grade 2, the presence of dominant fibrosis with scattered tumor cells; grade 3, the presence of only scattered tumor cells in the space of fibrosis with/without acellular mucin; and grade 4, the absence of viable cancer cells.[21,22] Perioperative outcomes were also collected and included skin-to-skin operation time, estimated blood loss during surgery, duration of hospital stay, status of temporary protective ileostomy, and postoperative morbidity.
After recovering from surgery, the patients were clinically observed in an outpatient clinic every 3 months for the first 2 years and every 6 months for the subsequent 3 years. Follow-up abdomen and chest CTs were obtained every 6 or 12 months. The main endpoint of this study was the 5-year LR rate, which was defined as tumor recurrence within the pelvic cavity. The secondary endpoint was the 5-year disease-free-survival (DFS). DFS was defined as the time from curative surgery to distant metastasis or LR. LR and DFS were confirmed by a combination of clinical, radiologic, histopathologic, and surgical findings.
2.4 Statistical Analysis
Statistical analyses were performed using statistical software packages (SPSS, version 22, SPSS, Chicago, IL; MedCalc, version 16.2.0, MedCalc Software bvba, Ostend, Belgium). All continuous variables are expressed as the mean ± standard deviation. Given small number of study cohort, all percentages were rounded to integers. To compare categorical variables between the 2 groups, which were treated differently with surgery alone or PCRT + surgery, we used a χ2 or a Fisher exact test as appropriate. In the case of continuous variables, an independent t test or Mann-Whitney U test was performed. To eliminate the inherent bias in study cohort, a 1:1 propensity score-matched analysis was used. Propensity scores were calculated by using a logistic regression model with the dependent variable defined as the odds of undergoing a surgery alone and the independent variables as age, sex, body mass index, histologic grade, carcinoembryonic antigen, operation method, follow-up period, MRI-assessed tumor height, and presence or absence of MRI-assessed LN metastasis. The Kaplan-Meier method with a log-rank test was used to compare the survival difference between the groups. A P value <0.05 indicated a statistically significant difference.
3 Results
3.1 Demographics of the study cohort
Of the 203 patients enrolled, 140 patients in 70 pairs were finally assigned to each differently treated group, either surgery alone versus PCRT + surgery, after propensity score-matching (Table 1). No covariates exhibited a large imbalance such that a standardized mean difference was >0.25 between the 2 groups. The mean follow-up period of the 140 matched patients was 45.7 ± 19.8 months. Fifteen (11%) patients developed postoperative distant metastases and/or LR. Of these, 13 (9%) patients had distant metastases alone, and 1 (1%) had LR alone. One (1%) patient had both distant metastases and LR. The recurrent sites are summarized in Table 2. The overall 5-year LR rates and DFS were 2% (95% confidence interval [CI] 0.4%–6.1%) and 88% (95% CI% 80.6–92.5%), respectively.
Table 1 Baseline characteristics of the study cohort.
Table 2 Recurrent sites in the matched study cohort.
3.2 Comparison of histopathologic and perioperative outcomes
Histopathologic and perioperative outcomes are summarized in Tables 3 and 4, respectively. In the PCRT + surgery group, histopathologic TRG 0 was observed in 1 (1%) patient, TRG 1 in 13 (19%) patients, TRG 2 in 19 (27%) patients, TRG 3 in 25 (36%) patients, and TRG 4 in 12 (17%) patients. The longitudinal tumor size, mean length of PRM, PNI status, median number of retrieved LNs, and the tumor stage were significantly different between the 2 groups. Owing to the therapeutic effect of the PCRT, the histopathologic outcomes in terms of those variables were better in the PCRT + surgery group than in the surgery-alone group. Specifically, the PNI rate was lower in the PCRT + surgery group than in the surgery-alone group (17% vs. 4%, P = 0.03). The final histopathologic tumor stage was also significantly lower in the PCRT + surgery group (P = 0.009). However, other histopathologic outcomes, including the mean length of the DRM, CRM, LVI, and LN stage, were not significantly different between the groups.
Table 3 Histopathologic outcomes in the matched study cohort.
Table 4 Perioperative outcomes in the matched study cohort.
In terms of the perioperative outcomes, the mean operation time and protective ileostomy rate were significantly different between the 2 groups. The mean operation time was significantly shorter in the surgery-alone group than in the PCRT + surgery group (178.8 ± 69.8 vs. 206.1 ± 76.9 minutes; P = 0.03). The protective ileostomy rate was also lower in the surgery-alone group (11% vs. 47%; P < 0.001). However, other perioperative outcomes, including estimated blood loss, mean duration of hospital stay, and postoperative morbidity rate, did not reach statistical significance. In terms of the postoperative morbidity rate, 13 patients (19%) in the surgery-alone group and 11 patients (16%) in the PCRT + surgery group had postoperative complications. In both groups, the main complication was anastomosis leakage.
3.3 Comparison of oncologic outcomes
The oncologic outcomes are provided in Table 5, and the Kaplan-Meier survival curves are illustrated in Figure 2. In the unmatched study cohort (n = 203), neither the 5-year LR rate nor the DFS was significantly different between the groups (the 5-year LR rate, P = 0.40; the 5-year DFS, P = 0.23). The 5-year LR rate of the surgery-alone group was 1% (95% CI 0.1%–6.3%) versus 3% (95% CI 0.6%–9.7%) in the PCRT + surgery group. The 5-year DFS of the surgery-alone group was 92% (95% CI 84.5%–95.9%) versus 88% (95% CI 78.0%–93.1%) in the PCRT + surgery group.
Table 5 Local recurrence and disease-free survival in the study cohort.
Figure 2 Kaplan–Meier survival curves of the 5-year LR rate and DFS in the unmatched and matched study cohort. (A, B) unmatched cohort (n = 203). Neither the 5-year LR rate nor the DFS was significantly different between the 2 groups (the 5-year LR rate, P = 0.40; the 5-year DFS, P = 0.23). (C, D) matched cohort (n = 140). Neither the 5-year LR rate nor the DFS was significantly different between the groups (the 5-year LR rate, P = 0.93; the 5-year DFS, P = 0.94). DFS = disease-free survival, LR = local recurrence, PCRT = preoperative chemoradiotherapy.
In the matched study cohort (n = 140), neither the 5-year LR rate nor the DFS was significantly different between 2 groups (the 5-year LR rate, P = 0.93; the 5-year DFS, P = 0.94). The 5-year LR rate of the surgery-alone group was 2% (95% CI 0.2%–10.9%) versus 2% (95% CI 0.2%–10.1%) in the PCRT + surgery group. The 5-year DFS of the surgery alone group was 87% (95% CI 74.6%–93.7%) versus 88% (95% CI 77.8%–93.9%) in the PCRT + surgery group.
3.4 Subgroup analysis for LN stage
The correlation between MRI and pathology-based LN staging was provided in supplement Table 1. The 5-year LR rate and DFS according to histopathologic LN status were summarized in Table 6. In patients with histopathologic LN−, neither the 5-year LR rate nor the DFS was significantly different between the surgery alone (n = 49) or the PCRT + surgery (n = 60) groups (the 5-year LR rate, P = 0.81; the 5-year DFS, P = 0.52). Furthermore, in patients with histopathologic LN+, neither the 5-year LR rate nor the DFS was significantly different between the surgery-alone (n = 21) or the PCRT + surgery (n = 10) groups (the 5-year LR rate, P > 0.99; the 5-year DFS, P = 0.18).
Table 6 5-Year local recurrence and disease-free survival of matched cohort according to histopathologic LN status.
In both groups, the surgery-alone versus the PCRT + surgery group, the 5-year LR rate was not significantly different between histopathologic LN+ and LN− patients (the surgery-alone group, P = 0.49; the PCRT + surgery group, P = 0.68). In the surgery-alone group, the 5-year LR rate of LN− patients (n = 49) was 2% (95% CI 0.1%–15.8%) versus 0% in LN+ patients (n = 21). In the PCRT + surgery group, the 5-year LR rate of LN− patients (n = 60) was 2% (95% CI 0.1%–11.8%) versus 0% in LN+ patients (n = 10).
4 Discussion
We hypothesized that a combination of MRI-assessed T3ab and clear MRF could be used as a highly selective indication of surgery alone in mid/lower T3 rectal cancer. This suggestion is similar to that of the Magnetic Resonance Imaging and Rectal Cancer European Equivalence (MERCURY) group.[14] The MERCURY group suggested that T3ab, clear MRF, and absent extramural venous invasion (EMVI) could be used as a potential indication of surgery alone in T3 rectal cancer. In the present study, we did not include EMVI status. This is because the prevalence rate of EMVI in patients with T3ab and clear MRF is very low at approximately only 5% in our experience and because in those patients, most EMVI is detected in only small venules perforating the normal outer rectal wall. Sohn et al[23] reported that MRI-detected EMVI involving a large vessel (≥3 mm) was a strong risk factor for a poor prognosis, whereas EMVI involving a small vessel was not. Talbot et al[24] also demonstrated that patients with pathology-detected EMVI on thick-walled vessels had a poorer prognosis than EMVI on thin-walled vessels. Although the prognostic value of MRI-detected EMVI on small perforating venules has not been well established, our suggestion based on the above-mentioned studies deserves careful consideration. In our hypothesis, the LN and Pelvic LN status was also excluded as a potential indication of surgery alone in T3 rectal cancer. Given that the current NCCN guideline recommends PCRT for all patients with LN metastasis, interpretation of this should be very cautious.[1] This is because there is a possibility that the LN status might not affect the LR in cases of qualified surgery.[25] A randomized controlled trial (RCT) by Quirke et al[26] showed that there was no difference in the LR rate between LN+ and LN− patients (6% vs. 5%). The result from the subgroup analysis of our study was also similar. In both groups, the 5-year LR rate was not significantly different between histopathologic LN+ and LN− patients. Moreover, MRI has a relatively lower diagnostic accuracy for the prediction of LN metastasis.[27,28] Our study demonstrated that the diagnostic accuracy of MRI for the prediction of LN metastasis was also approximately 60% in the surgery alone group. Accordingly, the paradigm shifts of current treatment planning based on MRI-predicted LN may be necessary.
In our study, the histopathologic outcomes, such as the PNI status and the tumor stage, were better in the PCRT + surgery group than in surgery-alone group. This was attributed to the therapeutic effect of the PCRT. However, the mean length of the DRM, CRM, and LVI status, which has relatively more important implications in terms of the LR, was not significantly different. Specifically, it is notable that the proportion of patients with a positive CRM, which is the strongest risk factor for LR, was not different between the groups.[17] In terms of the perioperative outcomes, surgery alone might be equivalent to or better than PCRT + surgery. In our study, the mean operation time in the surgery-alone group was approximately 30 minutes shorter than in the PCRT + surgery group. Additionally, the temporary protective ileostomy rate was also approximately 35% lower in surgery-alone than in PCRT + surgery group. Even given the cost-effectiveness and the adverse effects of irradiation as delayed wound healing, small bowel obstruction, diarrhea, anastomosis stricture, among others, surgery alone might be better than PCRT + surgery in patients with MRI-assessed T3ab and clear MRF mid/lower rectal cancer.[29]
In the present study, we demonstrated that in patients with MRI-assessed T3ab and clear MRF mid/lower rectal cancer, the long-term outcomes of surgery alone were comparable with PCRT + surgery. Surgery alone achieved a 5-year LR rate of approximately 2% and a 5-year DFS of 90%. The oncologic outcomes of those patients were similar to those of stage I patients.[30] Given this result, surgery alone in mid/lower rectal cancer patients with MRI-assessed T3ab and clear MRF can be acceptable in terms of oncologic outcomes. Previous studies also support this. Merkel et al[8] reported that the 5-year survival rate of pT3ab cancer that was treated by radical surgery alone was similar to pT2 cancer regardless of LN status. Strassburg et al[31] suggested that the assessment of MRF status based on preoperative MRI could be used as an individualized indication of PCRT. Baek et al[32] demonstrated that the oncologic outcome of T3 rectal cancer without PCRT could be acceptable in terms of LR. Although our study is not a RCT, it can be suggested that surgery alone is feasible in MRI-defined favorable T3 mid/lower rectal cancer patients with T3ab and clear MRF. A further RCT is necessary to confirm these findings.
Our study had several limitations. First, the study cohort was small, and the design was a case-matched retrospective analysis. Additional case-matching covariates could not be applied because of small numbers in the study cohort. Although adjuvant therapy may have an effect on the prognosis, the present study did not consider it as a case-matching covariate.[33] It would be noteworthy if a RCT with large study cohort was conducted. Furthermore, we did not calculate the sample size to enhance the statistical power. Third, although we tried to eliminate the inherent bias using the propensity score-matched analysis, a few more patients with lower rectal cancer were assigned to the PCRT + surgery group. The possibility cannot be completely excluded that this influenced the study result.
In conclusion, although it had several limitations, our study demonstrated that, in patients with MRI-assessed T3ab and clear MRF mid/lower rectal cancer, the long-term outcomes of surgery alone were comparable with those of PCRT + surgery. The suggested MRI-assessed T3ab and clear MRF can be used as a highly selective indication of surgery alone in mid/lower T3 rectal cancer. Additionally, in those patients, surgery alone can be tailored to the clinical situation. Further validation studies with prospective design are required.
Supplementary Material
Supplemental Digital Content
Abbreviations: 5-FU = 5-fluorouracil, CI = confidence interval, CRM = circumferential resection margin, DFS = disease-free-survival, DRM = distal resection margin, EMVI = extramural venous invasion, LARC = locally advanced rectal cancer, LF = leucovorin and 5-fluorouracil, LN = lymph node, LR = local recurrence, LVI = lymphovascular invasion, MERCURY = Magnetic Resonance Imaging and Rectal Cancer European Equivalence, MRF = mesorectal fascia, NCCN = National Comprehensive Cancer Network, PCRT = preoperative chemoradiotherapy, PNI = perineural invasion, PRM = proximal resection margin, RCT = randomized controlled trial, RT = radiation therapy, TRG = tumor regression grade.
The authors report no conflicts of interest.
Supplemental Digital Content is available for this article.
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Medicine (Baltimore)Medicine (Baltimore)MEDIMedicine0025-79741536-5964Wolters Kluwer Health 28328821MD-D-16-0130210.1097/MD.0000000000006363063635300Research ArticleObservational StudyIs carotid sonography a useful tool for predicting functional capabilities in ischemic stroke patients following carotid artery stenting? Lin Chih-Ming MD MPHabSu Jian-Chi MScChang Yu-Jun PhDdLiu Chi-Kuang MDeLu Henry Horng-Shing PhDcf∗Jong Yuh-Jyh MD DMScibghi∗Rosca. Elena Cecilia a Department of Neurology, Changhua Christian Hospital, Changhuab Department and Institute of Biological Science and Technology, College of Biological Science and Technologyc Institute of Statistics, College of Science, National Chiao Tung University, Hsinchud Epidemiology and Biostatistics Centere Department of Medical Imaging, Changhua Christian Hospital, Changhuaf Big Data Research Centerg Institute of Molecular Medicine and Bioengineering, College of Biological Science and Technology, National Chiao Tung University, Hsinchuh Graduate Institute of Clinical Medicine, College of Medicinei Departments of Pediatrics and Laboratory Medicine, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung, Taiwan.∗ Correspondence: Henry Horng-Shing Lu, Institute of Statistics and Big Data Research Center, National Chiao Tung University, 1001 Ta Hsueh Road, Hsinchu 30010, Taiwan (e-mails: hslu@stat.nctu.edu.tw); Yuh-Jyh Jong, Department and Institute of Biological Science and Technology, College of Biological Science and Technology, National Chio Tung University, 1001 Ta Hsueh Road, Hsinchu 30010, Taiwan (e-mail: yjjongnctu@gmail, yjjong@gap.kmu.edu.tw).3 2017 24 3 2017 96 12 e636324 2 2016 12 2 2017 16 2 2017 Copyright © 2017 the Author(s). Published by Wolters Kluwer Health, Inc.2017This is an open access article distributed under the terms of the Creative Commons Attribution-Non Commercial License 4.0 (CCBY-NC), where it is permissible to download, share, remix, transform, and buildup the work provided it is properly cited. The work cannot be used commercially without permission from the journal. http://creativecommons.org/licenses/by-nc/4.0Supplemental Digital Content is available in the text
Abstract
Carotid stenosis is a major cause of stroke and timely intervention with stenting manipulation can significantly reduce the risk of secondary stroke. The impact of stenting procedures on patient functional capabilities has not yet been explored. The primary aim of this study was to examine associations between periprocedural carotid sonography parameters and post-treatment functional capabilities in stroke patients.
Sixty-seven patients who received carotid stenting at 1 angiography laboratory were included. Prestenting and poststenting carotid duplex data were recorded and resistance index (RI) differences at various carotid system locations were compared. The modified Rankin Scale (mRS) was used to assess functional capability. All of the studied parameters were analyzed by SPSS (version 16.0, SPSS Inc, Chicago, IL).
Following stenting, mRS scores improved (n = 44) or remained stationary (n = 23). Net contralateral internal carotid artery (ICA) RI for patients with improved mRS was lower compared to that for patients with stationary mRS (median = 0.040 vs 0.11; P = 0.003). The contralateral common carotid artery RI before and after stenting differed significantly (P < 0.050) in both. The ipsilateral ICA RI differed (P < 0.050) only in patients with improved mRS. The difference in mean transit time, Barthel index, net ipsilateral ICA RI, net contralateral external carotid artery RI, postipsilateral common carotid artery RI, and postipsilateral ICA RI differed significantly between different baseline stroke severity groups (P < 0.050).
Carotid artery stenting improved physical function in a proportion of ischemic stroke patients with carotid stenosis. Carotid ultrasound is a useful assessment tool to predict likely functional outcomes following carotid artery stenting.
Keywords
carotid artery stentingcarotid stenosisischemic strokemodified Rankin Scaleresistance indexOPEN-ACCESSTRUE
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1 Introduction
Stroke is one of the leading causes of death worldwide. Carotid stenosis is the most well-known risk factor for stroke,[1] in part due to its association with recurrent stroke and lumen reduction of >50% increases the risk of stroke or recurrent stroke by 2- to 3-fold.[2] It is well recognized that prompt management of carotid artery stenosis with stenting can prevent stroke or recurrent stroke.[3,4] However, associations between periprocedural carotid ultrasound parameters, baseline characteristics, and post-treatment functional capabilities in first-time stroke patients have not been investigated.
Extracranial carotid ultrasound[5] is noninvasive and mobile, and requires no contrast medium, making it a useful assessment tool in carotid stenosis stroke patients.[6] However, the role of carotid ultrasound in evaluating the blood flow between the prestenting and poststenting phases has, to the best of our knowledge, not been reported or validated in stroke patients with carotid stenosis.
According to TOAST criteria[7–9] 30% to 35% of all acute ischemic stroke cases can be attributed to vascular atherosclerotic changes. There is an increased risk of recurrent stroke in this group of patients due to the high prevalence of moderate to severe stenosis with >50% lumen reduction. Carotid artery stenting can effectively prevent secondary stroke in addition to securing the main blood supply to the brain parenchyma[10–12] and the current guidelines[13–15] recommend carotid artery stenting when the diameter of the lumen is reduced by >70%, if assessed by noninvasive imaging, or >50%, if assessed by catheter-based imaging. Despite the efficacy of carotid artery stenting being well established in ischemic stroke patients with stenosis, the documented outcomes for these patients are heterogeneous, and the procedure may be associated with significant morbidity.[16,17]
The primary aim of this study was therefore to investigate whether the functional outcomes following carotid artery stenting in first-time stroke patients with carotid stenosis were associated with baseline characteristics and/or parameters measured by ultrasound. Changes in the resistance index (RI) values at various locations on the ipsilateral and contralateral carotid systems were investigated to determine whether the RI plays a role in the early prediction of outcomes.
2 Materials and methods
A total of 67 ischemic stroke patients, experiencing their first stroke, who had received carotid artery stenting at the angiography laboratory of the Department of Medical Imaging of Changhua Christian Hospital, Changhua, Taiwan, were enrolled in this study. Patients were transferred from an outpatient clinic, an emergency department, or a branch hospital and were subsequently admitted to Changhua Christian hospital for examination and treatment. Inclusion criteria were the following: a history of an initial, first-time, ischemic stroke, with the cause of stroke confirmed as due to carotid stenosis, age >20 years, carotid stenosis >50% lumen reduction by angiography, no documentation of recurrent stroke during the study period, and follow-up available for at least 12 months following the stenting procedure. All patients had ischemic infarctions in the middle cerebral artery (MCA) territory verified by imaging. Patients were excluded if they had cerebral hemorrhage, cerebral arteriovenous malformations and aneurysms, or bilateral moderate to severe carotid stenosis. Patients who were lost to follow-up and those who were followed up for <12 months after stenting were also excluded.
All included patients were stented 1 month after the index stroke event by the same neuroradiologist (Dr Chi-Kuang Liu). Carotid ultrasound was conducted before stenting and 4 weeks after the procedure. Follow-up was for an average of 1 year allowing for assessment of midterm functional outcomes. All patients had a detailed history of baseline (Table 1) and biochemical characteristics and had undergone neuroimaging examinations (digital subtraction angiography [DSA], computed tomography angiography and perfusion [CTA/P], and magnetic resonance imaging and angiography [MRI/A]) before stenting. The study was approved by the Institutional Review Board of Changhua Christian Hospital. The study was retrospective and the informed consent was not required by the Institutional Review Board of Changhua Christian Hospital (see appendix IRB approval).
Table 1 Baseline patient clinical characteristics.
2.1 Baseline patient clinical characteristics
Patient demographics and pertinent risk factors (gender, age, diabetes mellitus, hypertension, dyslipidemia, Barthel index, atrial fibrillation, chronic heart failure, gouty arthritis, chronic kidney disease, body mass index, weight, height, systolic blood pressure, diastolic blood pressure, and admission score of National Institute of Health Stroke Scale) along with biochemical parameters (creatinine, low-density lipoprotein, uric acid, fasting blood sugar, and glycated hemoglobin levels) were abstracted from patient medical records to a standardized form. The modified Rankin Scale (mRS) was used to evaluate patient functional capacity. Each patient was evaluated at least twice using the mRS, before stenting and after the stenting procedure, in an outpatients’ clinic, with a minimum of 12 months between the 2 assessments. An mRS score of 0 to 1 generally indicates neurological stability, although mild neurological symptoms may be noticed; a score of 2 to 3 denotes moderately affected daily life activity; and a score of ≥4 indicates that intensive care is required and there is a high risk of death. The Barthel index was recorded before stenting and patients were classified into 2 comparison groups (Barthel index 0–60 vs 61–100).[18,19]
2.2 Cervical carotid ultrasound examination
Cervical carotid artery ultrasound examination was performed at our ultrasonography laboratory (Philips iE33 7-MHz linear transducer). Cross-sectional B-mode scanning was performed to check for intraluminal plaque and the longitudinal screening method was adopted to confirm the presence of plaque. The classification of plaques into subtypes 1, 2, 3, or 4 according to the International Classification System[20] was assessed by consensus of 2 physicians. In case of a disagreement between the physicians, a third physician assessed the classification. The intima–media thickness of the midportion of the common carotid artery (CCA) was measured on the ipsilateral side of the index stroke event. Peak systolic velocity, end-diastolic velocity, and the RI of the CCA, internal carotid artery (ICA), external carotid artery (ECA), and ophthalmic artery (OA) were measured bilaterally; reversal of blood flow in the OA was also measured. Forward flow was defined as blood flow detected away from the stenotic ipsilateral carotid artery, whereas reverse flow was defined as blood flow into the carotid artery. The degree of carotid stenosis and parameter classification was calculated according to the European Carotid Surgery Trial method.[21] The calculated ICA/CCA ratio[22,23] was defined as the ratio of the peak systolic velocity of the ICA to that of the CCA for each patient.
The RI data from prestenting and poststenting phases were integrated. RI parameters regarding the bilateral carotid systems of the patients are defined as follows, and each set of RI parameters was tested to determine the statistical significance:1. Net RI: The absolute prestenting and poststenting RI values of each location in the carotid examination
2. Ratio RI: The prestenting and poststenting RI values of each location in the carotid examination
3. Pre-RI: The RI value of each location before stenting in the carotid examination
4. Post-RI: The RI value of each location after stenting in the carotid examination
2.3 Neuroradiological examinations
2.3.1 Magnetic resonance imaging and angiography
Structural and functional magnetic resonance imaging (MRI) and angiographic examinations were performed using a standard stroke evaluation protocol using a 3-T MRI scanner (MAGNETOM Verio, Siemens Healthcare, Malvern, PA) or 1.5-T MRI scanner (MAGNETOM Aera, Siemens Healthcare) with a cervical coil. The entire imaging time was approximately 7 minutes. The following 3 parameters were derived from MRI/A:1. Ipsilateral MCA stenosis or occlusion represented whether the patients had concomitant MCA focal stenosis or occlusion on magnetic resonance angiography (MRA), which was confirmed through DSA.
2. Intracranial posterior circulation stenosis or occlusion represented whether the patients had incidental (either intracranial vertebral or basilar artery) focal stenosis or occlusion on MRA, which was confirmed through DSA.
3. Stroke location was categorized into cortical, subcortical, and cortical and subcortical regions.
2.3.2 DSA and stenting
The stenting procedure is illustrated in Fig. 1. Biplanar intra-arterial DSA was performed using a biplanar flap panel rotational angiography unit (Axiom Artis Zee, Siemens Healthcare). A self-expanding Carotid Wallstent (7 × 30 mm) was used. The stent was delivered coaxially through the guiding catheter into the stenotic area.
Figure 1 An example of left-sided severe internal carotid artery stenosis undergoing carotid stenting treatment. A 67-year-old male patient manifested with right-sided hemiparesis and dysarthria, 24 hours before admission to our neurology ward. (A) Reconstruction imaging of digital subtraction angiography showed a short segmental high-grade stenosis (>70%) involving the proximal part of left internal carotid artery. (B) The insertion of E-Z wire to prevent distal emboli migration. After the stent was placed, a 6 × 20 mm balloon catheter was used for postdilation purpose. (C) The computed tomographic angiography (CTA) showed evidence of segmental stenosis at left cervical internal carotid artery, severe degree (64% based on area measurement). (D) B-mode imaging of cervical color-coded carotid duplex showed 60.8% stenosis detected by the cross-sectional maneuver.
2.3.3 CTA/P imaging
Computed tomography angiography examinations were performed using a second-generation dual-source computed tomography scanner (SOMATOM Definition Flash, Siemens Healthcare, Forchheim, Germany). Perfusion data sets were postprocessed on a Siemens Multimodality Workplace Workstation (Siemens Medical, Erlangen, Germany), yielding mean transit time (MTT), cerebral blood volume (CBV), cerebral blood flow (CBF), and time to peak (TTP) maps. Other CTP parameters[24–27] were evaluated and defined as follows to test for association with the mRS score:1. Difference of mean transit time (dMTT): (Absolute value of the ipsilateral MTT) − (contralateral MTT of each patient)
2. rCBV: CBV ratio ([ipsilateral CBV]/[contralateral CBV])
3. CBV index: ([Ipsilateral CBV] − [contralateral CBV])/(contralateral CBV)
4. rCBF: CBF ratio ([ipsilateral CBF]/[contralateral CBF])
5. CBF index: ([Ipsilateral CBF] − [contralateral CBF])/(contralateral CBF)
6. TTP index: ([Ipsilateral TTP] − [contralateral TTP])/(contralateral TTP)
7. rMTT: MTT ratio ([ipsilateral MTT]/[contralateral MTT])
2.4 Statistical analyses
All statistical analyses were performed using the statistical package SPSS for Windows (version 16.0, SPSS Inc, Chicago, IL).
Prestenting and poststenting mRS scores were compared to determine patient outcomes and classified as improved, stationary, or deteriorated. Statistical comparisons were conducted using Pearson χ2 test.
Following classification, comparison of groups according to poststenting mRS score was conducted using all available recorded variables. The Mann–Whitney U test was used to determine differences in the means of continuous variables between the 2 groups. Categorical variables were compared using the χ2 test, or Fisher exact test, where appropriate. Univariate or multivariate logistic regression was employed to assess the significance of risk factors and to obtain odds ratios. A P value <0.050 was considered statistically significant. To further differentiate the 2 groups, the Wilcoxon signed-rank test was used to evaluate differences between the prestenting and poststenting RI values at each location in the bilateral carotid systems (CCA, ICA, ECA, and OA).
Further subgroup analysis was conducted in those patients showing improvement following stenting. Groups were differentiated on the basis of stroke severity as determined by mRS score; patients were categorized into 3 groups as follows: mild (mRS score improvement from 1 to 0 following stenting; n = 13), moderate (mRS score change from 2 to 1; n = 18), and severe (mRS score change from 4 to 3; n = 10). The Kruskal–Wallis test was used to determine whether any variable exhibited a significant difference among the 3 groups and the Jonckheere–Terpstra test was utilized to test for significance of trends.[28,29]
3 Results
Baseline characteristics are given in Table 1. Improved mRS score following stenting was observed in 44/67 (65.7%) ischemic stroke patients. In total, 42 patients improved by 1 point on the mRS scale and 2 patients improved by 2 points. The condition remained unchanged (stationary) in the remaining 23/67 (34.3%) patients after stenting (see Fig. 2; appendix supplementary table).
Figure 2 mRS score in ischemic stroke patients before and after carotid artery stenting. mRS = modified Rankin Scale.
When patients with an improved mRS score were compared to those with a stationary mRS score, no statistically significant differences were observed for any of the clinical parameters investigated, apart from net contralateral ICA RI. Net contralateral ICA RI was significantly lower following stenting in those patients exhibiting improved functioning, with a median ICA RI of 0.04 for patients with improved mRS compared to 0.11 for those with stationary mRS (P = 0.003; univariate analysis: odds ratio 5.279; 95% confidence interval 2.123, 12.342; P = 0.005).
In further analysis of the 2 groups, each RI location was compared for the prestenting and poststenting phases at various sites of the carotid systems (Table 2). The contralateral CCA RI for the stationary and improvement mRS groups differed significantly (0.76 vs 0.80; Wilcoxon signed-rank test, P = 0.008 and 0.009, respectively), whereas for the improved mRS group the ipsilateral ICA RI differed significantly following stenting (0.62 vs 0.71, respectively; P = 0.002).
Table 2 Periprocedural changes of the RI in the ipsilateral and contralateral carotid systems.
In a subgroup analysis, patients showing improved mRS after stenting were divided into 3 groups (mild, moderate, and severe) based on their mRS score. There were no statistically significant differences between the 3 groups with respect to clinical parameters, apart from the Barthel index at admission (Barthel index 0–60 vs 61–100; P < 0.050) (Table 3), dMTT, net ipsilateral ICA RI, net contralateral ECA RI, postipsilateral CCA RI, and postipsilateral ICA RI (P = 0.019, 0.045, 0.020, 0.025, and 0.032, respectively) (Table 4).
Table 3 Correlation between the Barthel index and 3 baseline mRS groups for patients with improved function after stenting.
Table 4 Critical clinical parameters in the 3 different baseline mRS groups.
In addition, as baseline mRS scores increased from mild to severe, the median values of the dMTT, postipsilateral CCA RI, and postipsilateral ICA RI also had a tendency to increase (Jonckheere–Terpstra test; P < 0.050).
4 Discussion
In the present study, no patients exhibited deterioration in mRS score following stenting and over half of the patients (65.7%) had improved mRS score, with the remainder having stationary or stable scores. This provides an indication that, in this patient series, carotid artery stenting was associated with improved outcomes in a substantial proportion of patients.
Carotid endarterectomy is an effective prophylactic procedure against stroke for patients with carotid stenosis discovered as an incidental finding,[30–32] although carotid stenting is a less invasive treatment and has been shown to be as beneficial as endarterectomy in patients with angiographic evidence of >60% stenosis or ultrasonographic evidence of 70% stenosis in primary prevention.[33] Treatment of patients with ischemic stroke and concomitant carotid stenosis is more complex. In patients of advanced age, carotid endarterectomy is preferred over carotid stenting because it has been shown to be associated with better outcome. All of the patients in this study underwent carotid stenting, even though most were of advanced age (median age 71 years), as there was no facility for carotid endarterectomy services at the institute where the study was conducted.
Computed tomography perfusion scanning is the standard tool for assessing cerebral perfusion in patients who undergo stenting[34–36] but requires the use of contrast medium that can result in significant morbidity, particularly in patients with impaired renal function. Extracranial carotid ultrasound has several advantages as it is noninvasive, mobile, and inexpensive and requires no contrast medium. The use of carotid ultrasound for assessing patients in this study and measurement of carotid duplex data at follow-up 4 weeks after stenting allows relatively immediate assessment of the effect of stenting. Combining carotid duplex data, parameters measured using carotid ultrasound, and patient condition at baseline and 12 months after stenting allows for the examination of any association between these variables and outcomes. To date no studies have examined the role of carotid artery RI in evaluating cerebral perfusion status after carotid stenting in first-time ischemic stroke patients, although RI has been widely used in nephrology.[37] Derchi et al measured RI in patients with renal dysfunction and reported that the risk of renal impairment increased 2-fold when renal RI was >0.63.[37] In addition, RI is effective in predicting kidney transplant outcomes.[37–42] The RI represents the general downstream blood vascular bed resistance level.[43] RI >0.75 denotes increased resistance of the downstream vascular bed, which can arise as a result of various factors including obstructions. Because CCA and ICA supply the majority of blood to the intracranial hemispheres, their RI values are lower than that of ECA under normal circumstances (CCA and ICA <0.75, ECA >0.75).
In the first-time ischemic stroke patients investigated in the present study net contralateral ICA RI was the most useful measurement for differentiating between patients whose mRS score remained stationary and those whose mRS score improved. The median net contralateral ICA RI value in the stationary group was >2-fold higher than that of the improved group (P = 0.005). This indicates that lower net contralateral ICA values measured in the peristenting period may be predictive of positive outcomes at 12-month follow-up, whereas higher values are less likely to be associated with improvement in mRS score at 12 months.
In the series of first-time ischemic stroke patients studied, following carotid artery stenting the ipsilateral CCA RI values tended to decrease, whereas those at other locations of the bilateral carotid systems mostly increased (Table 2). The CCA RI predicts the downstream vascular resistance bed, particularly in the ICA region. After stenting, the resistance is alleviated. The downstream vascular bed of the distal ICA, which can be revealed by the proximal ICA RI value, subsequently constricts the downstream vascular bed resulting in a relatively high resistance value; in other words, it may cancel out any increase in blood flow.[44,45]
In a subgroup analysis, patients were divided into 3 different baseline severity groups and it was found that, regardless of baseline mRS score, the improvement was uniform across all groups with an average 1-point decrease in score for each group, regardless of baseline severity. This is consistent with existing studies that have classified patients according to mRS score.[46–48] Furthermore, it was identified that of the 6 significant parameters, 4 were related to the RI, highlighting the importance of carotid ultrasound as an assessment tool.
Reversal of ophthalmic artery flow (ROAF) may result from intracranial hemodynamic compromise. Patients with unilateral high-grade cervical carotid stenosis in combination with intracranial stenosis appear to be at significantly increased risk for poor functional outcome and increased incidence of both intracranial stenosis[49] and ROAF.[50] Intracranial stenosis is a major stroke risk indicator as well as a predictor for worse stroke outcomes, and ROAF may provide partial compensation for improving stroke outcomes.[49]
Strengths of this study include that there was sufficient difference in time, of at least 12 months, between administering the first mRS test and the follow-up mRS. Furthermore, follow-up mRS was performed at an outpatient clinic that facilitated reproducibility of results and enabled patients’ neurological condition to stabilize following the stenting procedure.
Limitations of this study include that it was conducted at a single medical center with only 67 patients, and, hence, the sample size was small. The study results must be interpreted cautiously, and additional studies on larger samples sizes are required to confirm these findings. In addition, a control group for comparison with the experimental group was not included and all participants in this study were Asian and, therefore, the results may be relevant only to an Asian population. Poststenting neuroimaging such as brain MRI/A or CTA/P was not routinely arranged but would have added to this study. It is also possible that some subclinical stroke events following stenting may have been missed in this patient population, and this may have resulted in misinterpretation of the data. Finally, the patients were treated with dual antiplatelet therapy for at least 6 months after stenting. Stroke patients who had concomitant morbidities such as diabetes mellitus were also treated with appropriate drug therapy. The poststenting drug therapy might potentially confound the subsequent mRS value and therefore alter the functionality correlation.
Nevertheless, we have shown that carotid artery stenting has the capacity to improve mRS score in a proportion of ischemic stroke patients with carotid artery stenosis. Measurements of RI assessed by carotid ultrasound at 4 weeks poststenting correlate with midterm functional outcomes and may assist physicians in predicting the likely mRS score at 12 months following carotid artery stenting.
Supplementary Material
Supplemental Digital Content
Acknowledgments
With special thanks to Mu-Chien Sun, MD, MS of Stroke Center, Changhua Christian Hospital for his great support, and Ping-Yi Lin, PhD of Changhua Christian Hospital for her constructive comments.
Abbreviations: CBF = cerebral blood flow, CBV = cerebral blood volume, CCA = common carotid artery, CTA/P = computed tomography angiography and perfusion, DSA = digital subtraction angiography, ECA = external carotid artery, ICA = internal carotid artery, MRI/A = magnetic resonance imaging and angiography, mRS = modified Rankin Scale, MTT = mean transit time, OA = ophthalmic artery, RI = resistance index, TTP = time to peak.
Authorship: C-ML and Y-JJ performed study design and manuscript writing; J-CS performed data analysis and manuscript writing; Y-JC performed data analysis; C-KL collected data; HH-SL analyzed data and was instructor of study design.
Funding: This project is partially supported by Ministry of Science and Technology and Big Data Research Center of National Chiao Tung University, Taiwan.
The authors have no conflicts of interest to disclose.
Supplemental Digital Content is available for this article.
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Medicine (Baltimore)Medicine (Baltimore)MEDIMedicine0025-79741536-5964Wolters Kluwer Health 28328822MD-D-16-0419710.1097/MD.0000000000006365063657100Research ArticleObservational StudyDoes the longus colli have an effect on cervical vertigo? A retrospective study of 116 patientsLiu Xiao-Ming MDPan Fu-Min MDYong Zhi-Yao MDBa Zhao-yu MDWang Shan-Jin MD PhDLiu Zheng RNZhao Wei-dong MDWu De-Sheng MD, PhD∗Lin. Yung-Song Department of Spinal Surgery, Shanghai East Hospital, Tongji University School of Medicine, Shanghai, China.∗ Correspondence: De-Sheng Wu, Department of Spinal Surgery, Shanghai East Hospital, Tongji University School of Medicine, Shanghai, China (e-mail: eastspinewds@163.com).3 2017 24 3 2017 96 12 e636512 6 2016 14 2 2017 15 2 2017 Copyright © 2017 the Author(s). Published by Wolters Kluwer Health, Inc.2017This is an open access article distributed under the terms of the Creative Commons Attribution-Non Commercial-No Derivatives License 4.0 (CCBY-NC-ND), where it is permissible to download and share the work provided it is properly cited. The work cannot be changed in any way or used commercially without permission from the journal. http://creativecommons.org/licenses/by-nc-nd/4.0Abstract
The aim of the study was to evaluate the role of the longus colli muscles in cervical vertigo.
We retrospectively analyzed 116 adult patients who underwent anterior cervical discectomy and fusion (ACDF) during 2014 in our department. Patients were assigned to the vertigo group or the nonvertigo group. Demographic data were recorded. Inner distance and cross-sectional area (CSA) of longus colli were measured using coronal magnetic resonance imaging (MRI).
The vertigo group (n = 44) and the nonvertigo group (n = 72) were similar in demographic data. Mean preoperative Japanese Orthopaedic Association (JOA) score was higher in the vertigo group than in the nonvertigo group (P = 0.037), but no difference postoperatively. Mean JOA scores increased significantly postoperatively in both groups (P = 0.002 and P = 0.001). The mean vertigo score decreased significantly from pre- to postoperatively in the vertigo group (P = 0.023). The mean preoperative Cobb angle was significantly smaller in the vertigo group than in the nonvertigo group (P <0.001), but no significant difference postoperatively. After ACDF, the mean Cobb angle increased significantly in the vertigo group (P <0.001). The instability rates of C3/4 and C4/5 were significantly higher in the vertigo group (P <0.001 and P <0.001). The inner distance of longus colli was significantly shorter (P = 0.032 and P = 0.026) and CSA significantly smaller (P = 0.041 and P = 0.035), at C3/4 and C4/5 in the vertigo group than in the nonvertigo group. Mean Miyazaki scores were significantly higher in the vertigo group at C3/4 and C4/5 (P = 0.044 and P = 0.037). Moreover, a shorter inner distance and smaller CSA were related to a higher Miyazaki score.
Inner distance and cross-sectional area (CSA) of longus colli are associated closely with cervical vertigo. Shorter inner distance and smaller CSA of the longus colli muscles might be risk factors for cervical vertigo. ACDF provided a good resolution of cervical vertigo.
Keywords
ACDFcervical vertigodisc degenerationlongus colliMRIOPEN-ACCESSTRUE
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1 Introduction
Vertigo is 1 of the 20 most common causes of medical consultation in adult patients; in 80% cases, the symptoms are so severe that medical intervention is required.[1] One form of vertigo, cervical vertigo, is caused by neck disorders and is the most controversial.[2] Several hypotheses about cervical vertigo have been put forward,[3,4] but no study has investigated the relationship between the longus colli muscle and cervical vertigo. Previous studies have focused mainly on how the deep cervical flexor (DCF) muscles affect chronic neck pain.[5,6]
The longus colli are deep prevertebral muscles consisting of 3 parts. They originate on the anterior aspects of the vertebral bodies from C5 to T3, the anterior tubercle of the transverse processes of C3 to C5, and the sides of the T1 to T3 vertebral bodies bilaterally.[7,8] One study reported that longus colli muscles diverge laterally and have a close relationship with the sympathetic trunk.[9] We have observed clinically that the distance between the inner edges of the longus colli appear related to the type of cervical spondylosis, that is, the shorter the distance, the more likely that the patient will develop cervical vertigo. However, there is a lack of evidence of this relationship in the literature. Therefore, the aims of this study were (1) to determine whether the longus colli muscles are associated with cervical vertigo, (2) to determine the relationship between the longus colli and cervical stability, and (3) to determine whether anterior cervical discectomy and fusion (ACDF) can lead to a good prognosis for cervical vertigo.
2 Materials and methods
2.1 Ethics statements
Given the retrospective nature of the study, written consent was not obtained. However, we got the oral consent from all participants in the study by telephone contact, and patient records were anonymized and deidentified prior to analysis. Then, related data were extracted from hospital's electronic and written medical records. The study was reviewed and obtained the approval from Institutional Review Board of East Hospital, Tongji University.
2.2 Study population
We retrospectively identified 146 adult patients who underwent ACDF in our department during 2014. Patients diagnosed with cervical injury, tumor, infection, or hematoma, or who had previous cervical spine surgery were excluded. Cervical vertigo was diagnosed as follows: (1) obvious sympathetic symptoms such as vertigo, headache, tinnitus and palpitation, and so on; (2) careful diagnosis of cervical spondylosis with disc degeneration or definite spinal cord compression on MRI or cervical instability on x-ray; and (3) patients who suffered from neurological diseases, cardiovascular diseases, Ménière's disease, menopausal syndrome and neurosis, and so on, are excluded after consulting the otolaryngology and neurology departments. All the included patients were not alleviated of their symptoms after 3 months’ strict conservative therapy including cervical immobilization, traction, physiotherapy, and medication. All together, 116 patients were included in this study. Forty-six patients were set in the vertigo group and 72 patients with cervical radiculopathy, myelopathy, or radiculomyelopathy were in the nonvertigo group. Sex, age, body mass index (BMI), and presence of hypertension or diabetic mellitus (DM) were recorded.
2.3 X-ray assessment
Preoperative and postoperative sagittal cervical Cobb angles were measured and recorded in degrees. The global cervical Cobb angle was measured by first drawing 2 lines, 1 parallel to the inferior endplate of the C2 vertebra, and the other parallel to the superior endplate of the C7 vertebra [10] (Figs. 1B and 2B).
Figure 1 A 56-year-old female, complaint of walking clumsy and vertigo for 2 and half years, underwent ACDF after distinguishing from BPPV, vascular vertigo, neurological diseases, and so on, and failure of 3 months’ conservative treatment. Severity of vertigo was reduced from 4 to 1 after surgery and JOA score increased from 9 to 15 half year after surgery. Preoperative x-ray: (A) A-P view; (B) neutral lateral view; (C) extension lateral view; (D) flexion lateral view. Preoperative MRI: (E) sagittal MRI indicated disc degeneration and herniation of C4/5 and C5/6; (F) coronary MRI at C4/5 indicated CSA was 37.0 mm2 and inner distance of longus colli was 9.4 mm. 1 year's postoperative x-ray: (G) A-P view; (H) lateral view. ACDF = anterior cervical discectomy and fusion, BPPV = Benign Paroxysmal Positional Vertigo, CSA = cross-sectional area, JOA = Japanese Orthopaedic Association, MRI = magnetic resonance imaging.
Figure 2 A 58-year-old female, complaint of walking clumsy and radiation pain for both upper extremities for more than 2 years, JOA score was 6 pre-surgery, underwent ACDF after distinguishing from neurological diseases, and so on, and the failure of 3 months’ conservative treatment. Half year after surgery, the JOA score significantly increased from 6 to 15. Preoperative x-ray: (A) A-P view; (B) neutral lateral view; (C) extension lateral view; (D) flexion lateral view. Preoperative MRI: (E) Sagittal MRI indicated disc degeneration and herniation of C4/5 and C5/6; (F) Coronary MRI at C4/5 indicated CSA was 83.3 mm2 and inner distance of longus colli was 12.6 mm. 1 year's postoperative x-ray: (G) A-P view; (H) lateral view. ACDF = anterior cervical discectomy and fusion, CSA = cross-sectional area, JOA = Japanese Orthopaedic Association, MRI = magnetic resonance imaging.
Cervical instability was diagnosed using White's criteria: (a) more than 3.5 mm of horizontal displacement of 1 vertebra in relation to an adjacent vertebra measured on lateral roentgenograms (resting or flexion-extension), and (b) a difference of >11 degrees of rotation compared with that of either adjacent vertebra measured on a resting lateral or flexion-extension roentgenogram.[11] Preoperative resting anteroposterior and lateral radiographs are shown in Figs. 1A and B and 2A and B. Preoperative lateral flexion-extension radiographs are shown in Figs. 1C and D and 2C and D.
2.4 MRI protocol and data analysis
Prior to the study, we obtained cervical magnetic resonance imaging (MRI) for each subject. The MRI scans were obtained using a 3.0-tesla unit and phased-array spine coil with sagittal T1-weighted turbo spin echo, sagittal T2-weighted turbo spin echo, and axial T2-weighted turbo spin echo imaging protocol for the entire cervical spine. The subjects were placed in a comfortable and relaxed supine position with their hips flexed to 45 degrees and their legs supported by foam wedges. The head was positioned in a neutral position with the longus colli muscles relaxed. The distances between inner edges of the longus colli muscles were measured at each level from C2/3 to C6/7 (Figs. 1F and 2F). The cross-sectional areas (CSAs) were measured bilaterally at each disc level, and a mean value was calculated for each level (Figs. 1F and 2F). The severity of cervical disc degeneration was graded according to the 5-level system of Miyazaki et al,[12] with a higher grade indicating more severe degeneration. All data were collected by 1 experienced surgeon who was blinded to patients’ identities to diminish the measurement error.
2.5 Japanese orthopedic association scores and severity of cervical vertigo
Neurological function was assessed using the 17-item Japanese Orthopedic Association (JOA) score,[13] with higher scores representing better neurological function. Severity of cervical vertigo was assessed according to the standard of the American Academy of Otolaryngology-Head and Neck Surgery Committee on Hearing and Equilibrium.[14]
2.6 Surgical procedure
All patients underwent standard ACDF by the same surgeon. Using the method described by Smith and Robinson [15] and Cloward,[16] a right anterolateral approach to the anterior cervical disc via a 3-cm transverse skin incision was used. During the operation, a Caspar screw distracter was used to distract the involved disc space. A small Kerrison punch and curettes were used to remove anterior and posterior hypertrophic osteophytes, which were later used as bone graft material, and to perform cervical discectomy. The upper and lower endplates were prepared by removing the cartilage. Following this, with slight distraction of the disc space with the Caspar screw distracter, trialing was performed and a polyetheretherketone (PEEK) cage of appropriate size was selected. The inner cavity of the PEEK cage was then packed with the local bone chips obtained from removal of the anterior hypertrophic osteophytes. Anterior cervical plates were used in all patients. Surgical levels were decided by definite MRI finding of disc degeneration, spinal cord compression, or cervical instability on x-ray. Postoperative images are shown in Figs. 1G and H and 2G and H.
2.7 Statistical analysis
Data are presented as mean ± standard deviation. Age, BMI, JOA score, vertigo score, Cobb angle, CSA, inner distance, and Miyazaki score were compared using unpaired t tests. Sex and incidences of hypertension, DM, and instability were compared using the chi-square test. Differences with a P value < 0.05 or 0.01 were considered statistically significant. Pearson correlation analysis was adopted to identify the relationship between inner distance or CSA of longus colli and severity of disc degeneration. All statistical analyses were performed using the IBM SPSS Statistics software (SPSS) for Windows, Version 19.0 (IBM Corp., Armonk, NY).
3 Results
The vertigo group (n = 44; 18 males; mean age 53.81 ± 9.55 years) and the nonvertigo group (n = 72; 30 males; mean age 58.29 ± 9.86 years) show no intergroup differences in sex, age, BMI, and presence of hypertension and diabetes mellitus (Table 1). Table 2 presents pre- and postoperative results of JOA scores, vertigo scores, and Cobb angles. The mean preoperative JOA score was higher in the vertigo group than in the nonvertigo group (P = 0.037), but no difference in the mean JOA score was seen between groups postoperatively. Mean JOA scores increased significantly postoperatively in both the vertigo and nonvertigo group (P = 0.002 and P = 0.001, respectively). The mean vertigo score decreased significantly from pre- to postoperatively in the vertigo group (P = 0.023). The mean preoperative Cobb angle was significantly smaller in the vertigo group than in the nonvertigo group (P <0.001), but there was no significant difference between groups postoperatively. After ACDF, the mean Cobb angle increased significantly in the vertigo group compared with preoperatively (P <0.001) (Table 2).
Table 1 Demographic data of the 2 groups.
Table 2 Surgical results of the 2 groups.
The rates of instability of C3/4 and C4 /5 were significantly higher in the vertigo group (P <0.001 and P <0.001, respectively), but no significant intergroup differences were seen in instability of C2/3, C5 /6, and C6/7. The inner distance of longus colli was significantly shorter (P = 0.032 and P = 0.026, respectively), and CSA significantly smaller (P = 0.041 and P = 0.035, respectively), at C3/4 and C4/5 in the vertigo group than in the nonvertigo group, but the differences were not significant at C2/3, C5/6, and C6/7. Mean Miyazaki scores were significantly higher in the vertigo group at C3/4 and C4/5 (P = 0.044 and P = 0.037, respectively), but the differences were not significant at C2/3, C5/6, and C6/7 (Table 3). Moreover, a shorter inner distance was related to a higher Miyazaki score (r = –0.38, P = 0.026 of C3/4; r = –0.41, P = 0.019 of C4/5) and a smaller CSA of longus colli did as well (r = –0.26, P = 0.017 of C3/4; r = –0.33, P = 0.012 of C4/5).
Table 3 Comparison of radiography characteristics between the 2 groups in different disc levels.
4 Discussion
Colledge et al[17] suggested that cervical spondylosis is the second most frequent cause of vertigo in the elderly. However, because of the lack of a specific diagnostic test, cervical vertigo is a controversial entity.[4] According to our experience, a strict diagnose of cervical vertigo should be based on patients’ episode of sympathetic cervical spondylosis with other vertigo-inducing causes excluded. Several hypotheses regarding the etiology of cervical vertigo, such as neurovascular, somatosensory input, vascular and cervical instability, have been put forward.[4] In the present study, we used MRI to investigate the relationship between the longus colli muscles and cervical vertigo.
In recent years, researchers have focused on identifying and quantifying deficits in the DCF muscles in patients with neck pain.[18–21] Deficits in strength and endurance of the DCF muscles have been demonstrated in patients with chronic neck pain,[20] and some authors have observed that the CSA of the longus colli was smaller in patients with ossification of the posterior longitudinal ligament than in healthy control subjects.[18]
In the present study, shorter inner distance and smaller CSA of the longus colli at C3/4 and C4/5 were observed in the vertigo group. The rates of instability of C3/4 and C4 /5 were significantly higher, and the cervical spine significantly straighter, in the vertigo group than in the nonvertigo group preoperatively. Low activation of the DCF muscles has been shown to be associated with smaller muscle size, and a smaller muscle CSA is considered synonymous with atrophy and impairment; therefore, the size of the DCF muscles can be a good indicator of the significant stabilizing function of these muscles.[20–22] For this reason, we suspected that a shorter inner distance and smaller CSA would represent weaker longus colli muscles, which could lead to cervical spine instability and cause vertigo symptoms. Furthermore, in our study, we observed that a shorter inner distance and smaller CSA of longus colli were related to more severe disc degeneration, which also indicates that the weaker DCF is related to cervical dysfunction.
According to Falla et al[23] many proprioceptors are distributed over the longus colli and longus capitis muscles. Because these proprioceptors provide postural information as quickly as possible with early contraction during movements of the head or upper limbs, they facilitate suitable movements depending on the stability and posture of the neck region. However, atrophy of the longus colli muscles in patients with chronic neck pain can restrict neck stabilization during head or upper limb movements, resulting in unnatural and nonfunctional mobility of the neck, thus leading to cervical instability and cervical vertigo.
Researchers have also reported on the proximity of the longus colli muscles to the sympathetic trunk and the close relationship between these structures.[24,25] The sympathetic trunk would receive more stimulation from an unstable cervical spine, which could cause the sensation of vertigo; an unstable cervical spine would also cause friction on the cervical discs, which would exacerbate disc degeneration process. Future studies that attempt to analyze muscle the strength and the relationship between the sympathetic trunk and longus colli muscles are warranted.
In terms of treatment of cervical vertigo, all patients in the present study had a good prognosis from cervical vertigo after ACDF, and the mean Cobb angles increased significantly in the vertigo group. This could have resulted from postoperative stability of the cervical spine. Indeed, some studies have suggested that, because vertigo symptoms probably originate from irritation of the sympathetic trunk, nerve blockade and surgical denervation are 2 effective treatments.[26–28] It has also been suggested that routine ACDF with resection of the posterior longitudinal ligament could provide relief of sympathetic symptoms [29,30].
A number of interventions have focused on strengthening and re-training the longus colli muscles to improve function.[31] One neck-stabilization exercise attempts to flatten the curvature of the cervical spine without head movement by having patients lie in a supine position and perform chin nodding directed into the occiput, which selectively contracts the longus colli and longus capitis muscles.[32] Moon et al[31] also reported that co-contraction of the masticatory muscles during neck stabilization exercise can help to increase the thickness of the longus colli muscle. Falla et al[19] confirmed that reduced performance of the craniocervical flexion test was associated with dysfunction of the DCF muscles and suggested that this was a valid test for patients with neck pain. Gong[33] reported that massage of the longus colli muscles can be performed on inpatients who cannot perform neck-stabilizing exercises, or before performing other neck-stabilizing exercises. Physical therapy may therefore be a good choice for patients with longus colli muscle dysfunction.
Our study had some shortcomings in addition to its small sample size. First, we investigated only the longus colli, but stability of the cervical spine is maintained by a number of cervical muscles. Second, we did not use electromyography to confirm our suspici on that with a larger CSA and longer inner distance was associated with greater muscle strength. Third, the mechanism of cervical vertigo and disc degeneration with respect to the longus colli muscles was not thoroughly investigated and should be studied in the future.
5 Conclusion
MRI evaluation of 116 patients who underwent standard ACDF revealed that patients with shorter inner distance and smaller CSA of the longus colli muscles might have a greater tendency to develop cervical instability, and they were more likely to suffer from cervical vertigo and disc degeneration. ACDF was a suitable choice for patients with cervical vertigo.
Abbreviations: ACDF = anterior cervical discectomy and fusion, BMI = body mass index, CSA = cross-sectional area, DCF = deep cervical flexor, DM = diabetic mellitus, JOA = Japanese Orthopaedic Association, MRI = magnetic resonance imaging, PEEK = polyetheretherketone.
X-ML and F-MP contributed equally to this study.
Disclosure of interest: No benefits in any form have been or will be received from a commercial party related directly or indirectly to the subject of this manuscript.
Authorship: WDS and WSJ designed the study. LZ and BZY collected the data. LXM, PFM, YZY performed the statistics and drafted and revised the manuscript. WSJ, ZWD, WDS revised the manuscript. All authors read and approved the final manuscript.
Funding: Funded by the National Natural Science Foundation of China (81201418, 81572181), Key Discipline Construction Project of Pudong Health Bureau of Shanghai (PWZx2014–02), and China Scholarship Council (CSC NO. 201606260106).
The authors have no conflicts of interest to disclose.
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Medicine (Baltimore)Medicine (Baltimore)MEDIMedicine0025-79741536-5964Wolters Kluwer Health 28328823MD-D-16-0500810.1097/MD.0000000000006367063673500Research ArticleClinical Case ReportA case report of pycnodysostosis with atypical femur fracture diagnosed by next-generation sequencing of candidate genes Song Hyung Keun MDaSohn Young Bae MD, PhDb∗Choi Yong Jun MD, MScChung Yoon-Sok MD, PhDcJang Ja-Hyun MD, PhDdLiu. Miao a Department of Orthopedic Surgeryb Department of Medical Geneticsc Department of Endocrinology and Metabolism, Ajou University Hospital, Ajou University School of Medicine, Suwond Green Cross Genome, Yongin, Republic of Korea.∗ Correspondence: Young Bae Sohn, Department of Medical Genetics, Ajou University Hospital, Ajou University School of Medicine, 164 Worldcup-ro, Yeongtong-gu, Suwon 16499, Republic of Korea (e-mail: ybsohn@ajou.ac.kr).3 2017 24 3 2017 96 12 e63672 8 2016 14 2 2017 15 2 2017 Copyright © 2017 the Author(s). Published by Wolters Kluwer Health, Inc.2017This is an open access article distributed under the terms of the Creative Commons Attribution-Non Commercial-No Derivatives License 4.0 (CCBY-NC-ND), where it is permissible to download and share the work provided it is properly cited. The work cannot be changed in any way or used commercially without permission from the journal. http://creativecommons.org/licenses/by-nc-nd/4.0Abstract
Rationale:
Pycnodysostosis is a rare autosomal recessive skeletal dysplasia characterized by short stature, craniofacial dysmorphism, acro-osteolysis, osteosclerosis, and brittle bone with poor healing. Pycnodysostosis results from the deficient activity of cathepsin K, a lysosomal cysteine protease that is encoded by CTSK.
Patient concerns:
We report a Korean adult patient with pycnodysostosis and atypical femur fracture whose diagnosis was confirmed by next-generation sequencing (NGS) of candidate genes. A 41-year-old female patient was presented with a left femur fracture after falling down. Underlying sclerotic bone disease was suspected as a radiographic skeletal survey showed thickened cortical bones, and the total body bone density was increased (T score was 5.3, and Z score was 4.9).
Diagnoses:
We performed candidate gene sequencing of various sclerotic bone diseases for the differential molecular diagnosis of underlying sclerosing bone disease. Two heterozygous variants of CTSK were detected. One was a frameshift variant in exon 5, c.426delT (p.Phe142Leufs∗19), which was previously reported, and the other was a novel missense variant in exon 6, c.755G>A (p.Ser252Asn). Sanger sequencing of CTSK confirmed the 2 heterozygous variants and thus the patient was diagnosed with pycnodysostosis.
Interventions:
The patient had emergency surgery for subtrochantic femoral fracture.
Outcomes:
After 4 months of surgery, the patient had almost a full range of hip and knee movements and radiographs show the substantial bridging callus across the fracture.
Lessons:
Candidate gene sequencing could be a useful diagnostic tool for the genetically heterogeneous skeletal dysplasia group, especially in cases with a mild or atypical clinical phenotype.
Keywords
atypical femur fracturecandidate gene sequencingcathepsin KCTSKpycnodysostosisOPEN-ACCESSTRUE
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1 Introduction
Pycnodysostosis (OMIM 265800) is a rare autosomal recessive skeletal dysplasia with an estimated prevalence of 1 to 1.7 per million,[1] first described in 1962 by Maroteaux and Lamy.[2] Pycnodysostosis is presented with distinct clinical features including short stature, craniofacial dysmorphism, acroosteolysis of the terminal phalanges, osteosclerosis, and unusually brittle bone with poor healing. Craniofacial dysmorphism includes frontal bossing, opened fontanels, delayed closure of the cranial sutures, and an obtuse mandible angle. The abnormal skeletal morphology and bone composition in pycnodysostosis result from loss of cathepsin K activity, a lysosomal cysteine protease that is highly expressed in osteoclasts.[3] Cathepsin K is encoded by the CTSK gene located at chromosome 1q21.[4–6]
The phenotypes of pycnodysostosis are highly variable and overlap among various groups of skeletal dysplasia.[7,8] A specific diagnosis based on clinical manifestation is challenging in cases with atypical or mild clinical presentations. Molecular diagnostic approaches can be a useful diagnostic tool in these cases.
Here, we described the case of a Korean adult female patient with pycnodysostosis who sustained an atypical subtrochanteric femoral fracture with an impending subtrochanteric fracture in the contralateral femur. Because of her atypical presentation, a genetic diagnosis was carried out by next-generation sequencing (NGS) of candidate genes and later confirmed performing by Sanger sequencing. To the best of our knowledge, this is the first genetically documented case of pycnodysostosis in Korea.
2 Case report
A 41-year-old female patient fell from a chair and had sustained pain in her left thigh. Plain radiographs revealed a displaced left subtrochanteric transverse fracture with lateral beaking and thickened cortices as well as higher bone density in general. The contralateral femur also showed signs of cortical thickening and lateral beaking, raising concern for an impending fracture (Fig. 1A and B). She had previous traumatic fractures of the left tibia after a car accident 9 years ago and of the right clavicle 2 years ago that were completely healed. She was born from nonconsanguineous Korean parents. There was no family history of bone diseases. Her height was 160 cm and weight was 59 kg. A prominent forehead with frontal bossing and bitemporal narrowing were observed. However, her anterior fontanel was closed, mandibular angles appeared normal, and her fingers were not stubby. Serum laboratory tests revealed low osteocalcin and relatively low alkaline phosphatase considering concurrent bone fracture: calcium 8.7 mg/dL (normal range 8.6–10.2), phosphorus 3.1 mg/dL (2.5–4.5), PTH 52 pg/mL (11–62), 25(OH)D 13.2 ng/mL (9.0–37.6), alkaline phosphatase 43 U/L (35–104), and osteocalcin 6.1 ng/mL (8.0–36.0). The 24-hour urine calcium level was 40 mg (100–300), with inorganic phosphorus at 970 mg (400–1300) and creatinine at 1200 mg (740–1570).
Figure 1 Atypical femur fracture of the patient. (A) Preoperative radiographs of the patient with pycnodysostosis. (B) Intraoperative C-arm image shows a long osteotome used to open and widen the intramedullary canal. (C) Four months postoperatively, radiographs show that the left femur exhibited substantial bridging callus across the fracture, and the right femur was healed. (D) Scanogram shows good alignment with an incomplete union of the fracture.
On the day of her arrival at the emergency room, she underwent closed reduction and internal fixation with an antegrade femoral nail on the affected side and prophylactic internal fixation with the same implant on the contralateral side of the femur. The patient was placed supine on a fracture table under general anesthesia. The trochanter was inserted with a guide wire and opening reamer. It was impossible to pass the ball-tip guide wire into the intramedullary canal because the patient had extremely sclerotic bone and a narrow canal. Both cannulated powered and hand reamers did not work. The canal was opened with a long curved osteotome that was inserted into the intramedullary canal through a previously opened entry portal, and the ball-tip guide wire was positioned. The canal was then enlarged with flexible power reamers to a final diameter of 10.5 mm. A 9.3 mm ×380 mm lateral-entry nail (Zimmer Natural Nail, Zimmer, Warsaw, IN) was placed over the guide wire and locked using 2 proximal screws and 2 distal screws. Prophylactic fixation was performed on the contralateral side of the femur (Fig. 1C). Rehabilitation started on the first postoperative day with sitting and continuous passive motion of the knee and hip joints. Standing and ambulation using walking aids with tolerable weight bearing were allowed after 3 days following surgery.
After her general condition had recovered, a radiological skeletal survey was performed and generalized increased density of the bones in the entire skeleton was observed (Fig. 2A–D). A thickened base of the skull and mild scoliosis and spondylolysis of the L5 vertebrae were observed in whole spine radiography. X-ray assessment of the hand was relatively normal. Abnormal increased uptakes in both distal femurs, both tibiae, and both humeri were observed from a Tc-99m whole body bone scan (Fig. 2E). Total body bone densitometry using dual-energy X-ray absorptiometry (DEXA) showed an abnormal elevation of her bone density (T score was 5.3, and Z score was 4.9). Based on the clinical phenotype, adult-type osteopetrosis was initially suspected.
Figure 2 Skeletal survey of the patient. (A) Acroosteolysis of the distal phalanges was not observed in the hand radiograph. (B) Lateral cranial film shows thickening at the base of the skull and frontal bossing. (C) Mild scoliosis was observed on the whole spine posteroanterior (PA) radiograph. (D) Spondylolysis of the L5 vertebrae was observed on the lateral lumbar spine radiograph. (E) Multiple hot uptake was observed on the whole body bone scan.
For the differential molecular diagnosis of underlying sclerosing bone disease, we performed NGS of candidate genes for sclerotic bone diseases including various types of osteopetrosis (CLCN7, LRP5, CA2, TCIRG1, TNFSF11, PLEKHM1, and SNX10), pycnodysostosis (CTSK), craniometaphyseal dysplasia (ANKH), and craniodiaphyseal dysplasia (SOST). Briefly, genomic DNA was extracted from the peripheral blood. Library was prepared using the TruSight One Sequencing Panel (Illumina, Inc., San Diego, CA), which enriched a 12-Mb region spanning candidate genes with clinical relevance. Massively parallel sequencing was performed on the Illumina NextSeq platform. Average coverage of depth of the entire panel was 77×, and 97% of targeted bases were covered by 10× sequence reads. Coverage of the genes of interest is shown in Table 1. Sequence reads were aligned to hg19 with Burrow-Wheeler Aligner (version 0.7.12, MEM algorithm). Duplicate reads were removed by using Picard-tools1.96. Local realignment and base quality recalibration was done by The Genome Analysis Toolkit (GATK version 3.5). Variant calling was performed by GATK HaplotypeCaller. Variants were annotated by Variant Effect Predictor and dbNSFP. Candidate gene sequencing revealed 2 heterozygous variants in the CTSK gene that were confirmed by Sanger sequencing; 1 was a frameshift variant in exon 5, c.426delT (p.Phe142Leufs∗19), which was previously reported in patients with pycnodysostosis,[9] and the other was a novel missense variant in exon 6, c.755G>A (p.Ser252Asn) (reference sequence: NM_000396.3) (Fig. 3). The novel variant was not found in population databases such as 1000 Genomes, ESP6500, and ExAC. In silico analysis of p.Ser252Asn revealed a contradictory prediction result: damaging effect by SIFT and MutationTaster and tolerable effect by PolyPhen-2 HumVar. Codon 252 is highly conserved among species. Through targeted Sanger sequencing analysis of the patient's family members, it is likely that 2 different mutations are located on 2 different alleles because the daughter of the patient was a heterozygous carrier of the c.755G>A variant, and the son of the patient was a heterozygous carrier of the c.426delT mutation (Fig. 4). Unaffected family members had none of the 2 variants or only 1 heterozygous variant (Fig. 4). According to the American College of Medicine and Genetics guidelines for the interpretation of sequence variation,[10] the p.Ser252Asn variant could be classified as a likely pathogenic variant based on the following evidences absence from control population (PM2), trans-configuration with a pathogenic variant in autosomal recessive disorders (PM3), in silico prediction, and patient's phenotype. There was no pathogenic variant in the remaining 9 genes. Therefore, the patient was diagnosed with pycnodysostosis, and genetic counseling was performed.
Table 1 Depth of coverage of genes with interest.
Figure 3 CTSK variants detected by massively parallel sequencing and Sanger sequencing. Two heterozygous variants of CTSK were detected by next-generation sequencing of candidate genes and confirmed by Sanger sequencing. One was a frameshift variant in exon 5, c.426delT (p.Phe142Leufs∗19), and the other was a novel missense variant in exon 6, c.755G>A (p.Ser252Asn).
Figure 4 Pedigree of the patient and mutation analysis of the patient's family. Mutation analysis of the patient's family revealed that the daughter of the patient was a heterozygous carrier of the c.755G>A variant, and the son of the patient was a heterozygous carrier of the c.426delT mutation. Her mother was a heterozygous carrier of the c.755G>A variant. Her 2 unaffected brothers were heterozygous carriers, and 1 sister had none of the 2 variants.
One month postoperatively, the patient was able to bear full weight, and implants in both femurs were properly positioned with some sign of callus in the left femur. At the follow-up visit after 4 months, the patient was pain-free and had almost a full range of hip and knee movements, and radiographs show that the left femur exhibited substantial bridging callus across the fracture (Fig. 1D).
3 Discussion
Atypical subtrochanteric femoral fractures, as observed in our case, have been previously described in patients with pycnodysostosis.[11–14] Atypical femoral fractures are associated with high complication rates with operative fixation using conventional open reduction and internal fixation technique.[15] Several authors[16] have recommended the use of intramedullary nail systems for the management of atypical femoral fractures. However, intramedullary nailing in pycnodysostosis sometimes requires a high degree of skill because of the difficulties in reaming sclerotic bone.[11] In our case, a great deal of labor was required to accomplish intramedullary nailing. We used a long curved osteotome to widen the medullary canal, and it was effective. Poor healing of the bone structure is also an important clinical feature of pycnodysostosis.[17] This patient also suffered from an incomplete union of the femur fracture after 4 months of surgery. Bone fracture healing requires not only active bone formation to produce osteotylus but also degradation of excess bone matrix to restore the structure of the bone.[17] Cathepsin K plays a key role in osteoclast-mediated bone resorption during the healing process of bone fracture.[18,19]
A large number and overlapping phenotypes of various groups of skeletal dysplasia often result in challenges in performing a specific molecular diagnosis.[7,8] The role of NGS in the diagnosis of genetically heterogeneous disorders is well described.[20,21] Furthermore, NGS can be a useful diagnostic tool when clinical manifestations are atypical or mild. Therefore, we performed NGS of candidate genes for the differential diagnosis of this patient's underlying skeletal dysplasia. A precise molecular diagnosis of skeletal dysplasia is crucial for providing a prognosis of the patient and genetic counseling for the family.
Xue et al[1] reported that the most common phenotype of pycnodysostosis was short stature, which was presented in 95.9% of the 97 previously reported cases, followed by increased bone density, presented in 88.7% cases. However, pycnodysostosis exhibits similar clinical manifestations as adult-type osteopetrosis, including increased bone density, low bone turnover markers, and fragility fractures. Indeed, Pangrazio et al[20] reported that exome sequencing revealed 6 patients with pycnodysostosis among 27 patients who were clinically diagnosed with mild osteopetrosis. The typical phenotypes of pycnodysostosis include short stature, a peculiar facial appearance with frontal bossing and bitemporal narrowing, hypoplasia of the maxilla, absence of the mandibular angle, and stubby hands and feet with acroosteolysis.[1,22] Nevertheless, Pangrazio et al[20] reported that the obtuse mandibular angle and obvious acroosteolysis were not present in some genetically confirmed pycnodysostosis patients. We also initially suspected osteopetrosis based on the increased bone density of this patient. The phenotypic evidence for a diagnosis of pycnodysostosis seemed insufficient for this patient as her height was in a normal range and she only experienced 2 fractures until her forties. Radiological evaluation did not indicate obvious acroosteolysis on the distal phalanges or obtuse mandibular angle. However, candidate gene sequencing and Sanger sequencing revealed 2 heterozygous variants of CTSK. It is likely the 2 different mutations are located on the 2 different alleles because targeted Sanger sequencing analysis of the patient's family members showed a trans-configuration of the 2 variants (Fig. 4), which led to a diagnosis of pycnodysostosis. The mild phenotype of this patient could be possibly resulted from presence of other genes compensating the mutate CTSK gene, or uncertain compensatory regulation of other genes, which may inspire genomic investigation and developing treatment in the future.
4 Conclusions
In conclusion, we report a Korean adult patient with pycnodysostosis and atypical femur fracture whose diagnosis was confirmed by molecular genetic analysis. We suggest that NGS of candidate genes could be a useful diagnostic tool for the genetically heterogeneous skeletal dysplasia group, especially in cases with a mild or atypical clinical phenotype.
Abbreviations: DEXA = dual-energy X-ray absorptiometry, NGS = next-generation sequencing.
Funding: This study was supported by the new faculty research fund of Ajou University School of Medicine.
Ethical approval and patient's consent: Since this is a case report, institutional review board approval is not sought. However, written informed consent was obtained from patient for the publication.
The authors have no conflicts of interest to disclose.
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References
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[5] Polymeropoulos MH Ortiz De Luna RI Ide SE
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[6] Gelb BD Shi GP Chapman HA
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[9] Fujita Y Nakata K Yasui N
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[10] Richards S Aziz N Bale S
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[11] Kundu ZS Marya KM Devgan A
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[12] Nakase T Yasui N Hiroshima K
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[13] Hashem J Krochak R Culbertson MD
Atypical femur fractures in a patient with pycnodysostosis: a case report . Osteoporos Int
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[14] Yates CJ Bartlett MJ Ebeling PR
An atypical subtrochanteric femoral fracture from pycnodysostosis: a lesson from nature . J Bone Miner Res
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[15] Prasarn ML Ahn J Helfet DL
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[16] Shane E Burr D Ebeling PR
Atypical subtrochanteric and diaphyseal femoral fractures: report of a task force of the American Society for Bone and Mineral Research . J Bone Miner Res
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[17] Huang X Qi X Li M
A mutation in CTSK gene in an autosomal recessive pycnodysostosis family of Chinese origin . Calcif Tissue Int
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[18] Fratzl-Zelman N Valenta A Roschger P
Decreased bone turnover and deterioration of bone structure in two cases of pycnodysostosis . J Clin Endocrinol Metab
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[19] Novinec M Lenarcic B Cathepsin K
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Medicine (Baltimore)Medicine (Baltimore)MEDIMedicine0025-79741536-5964Wolters Kluwer Health 28328824MD-D-16-0722710.1097/MD.0000000000006371063716700Research ArticleObservational StudyEarly use of noninvasive techniques for clearing respiratory secretions during noninvasive positive-pressure ventilation in patients with acute exacerbation of chronic obstructive pulmonary disease and hypercapnic encephalopathy A prospective cohort studyWang Jinrong MDabCui Zhaobo MSb∗Liu Shuhong MSbGao Xiuling MScGao Pan BSbShi Yi MDad∗Guo Shufen MSbLi Peipei MScSchildgen. Oliver a Southern Medical University, Guangzhou, Guangdongb Department of Critical Care Medicinec Department of Respiratory and Critical Care Medicine, Harrison International Peace Hospital, Hengshui, Hebeid Department of Respiratory and Critical Care Medicine, Nanjing General Hospital of Nanjing Military Command, Nanjing, Jiangsu, China.∗ Correspondence: Yi Shi, Southern Medical University, Guangzhou, Guangdong, China (e-mail: iamwjr306@163.com); Department of Respiratory and Critical Care Medicine, Nanjing General Hospital of Nanjing Military Command, Nanjing, Jiangsu, China; Zhaobo Cui, Department of Critical Care Medicine, Harrison International Peace Hospital, Hengshui, Hebei, China (e-mail: zhaobocui2014@sina.com).3 2017 24 3 2017 96 12 e63712 12 2016 17 2 2017 17 2 2017 Copyright © 2017 the Author(s). Published by Wolters Kluwer Health, Inc.2017This is an open access article distributed under the terms of the Creative Commons Attribution-Non Commercial-No Derivatives License 4.0 (CCBY-NC-ND), where it is permissible to download and share the work provided it is properly cited. The work cannot be changed in any way or used commercially without permission from the journal. http://creativecommons.org/licenses/by-nc-nd/4.0Abstract
Noninvasive positive-pressure ventilation (NPPV) might be superior to conventional mechanical ventilation (CMV) in patients with acute exacerbations of chronic obstructive pulmonary disease (AECOPDs). Inefficient clearance of respiratory secretions provokes NPPV failure in patients with hypercapnic encephalopathy (HE). This study compared CMV and NPPV combined with a noninvasive strategy for clearing secretions in HE and AECOPD patients.
The present study is a prospective cohort study of AECOPD and HE patients enrolled between October 2013 and August 2015 in a critical care unit of a major university teaching hospital in China.
A total of 74 patients received NPPV and 90 patients received CMV. Inclusion criteria included the following: physician-diagnosed AECOPD, spontaneous airway clearance of excessive secretions, arterial blood gas analysis requiring intensive care, moderate-to-severe dyspnea, and a Kelly–Matthay scale score of 3 to 5. Exclusion criteria included the following: preexisting psychiatric/neurological disorders unrelated to HE, upper gastrointestinal bleeding, upper airway obstruction, acute coronary syndromes, preadmission tracheostomy or endotracheal intubation, and urgent endotracheal intubation for cardiovascular, psychomotor agitation, or severe hemodynamic conditions.
Intensive care unit participants were managed by NPPV. Participants received standard treatment consisting of controlled oxygen therapy during NPPV-free periods; antibiotics, intravenous doxofylline, corticosteroids (e.g., salbutamol and ambroxol), and subcutaneous low-molecular-weight heparin; and therapy for comorbidities if necessary. Nasogastric tubes were inserted only in participants who developed gastric distension. No pharmacological sedation was administered.
The primary and secondary outcome measures included comparative complication rates, durations of ventilation and hospitalization, number of invasive devices/patient, and in-hospital and 1-year mortality rates.
Arterial blood gases and sensorium levels improved significantly within 2 hours in the NPPV group with lower hospital mortality, fewer complications and invasive devices/patient, and superior weaning off mechanical ventilation. Mechanical ventilation duration, hospital stay, or 1-year mortality was similar between groups.
NPPV combined with a noninvasive strategy to clear secretions during the first 2 hours may offer advantages over CMV in treating AECOPD patients complicated by HE.
Keywords
chronic obstructive pulmonary diseasehospital outcomehypercapnic encephalopathynoninvasive positive-pressure ventilationrespiratory secretionssensorium levelOPEN-ACCESSTRUE
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1 Introduction
Chronic obstructive pulmonary disease (COPD) is a serious lung condition with a high incidence and mortality.[1,2] An acute exacerbation of COPD (AECOPD) can lead to life-threatening hypercapnic encephalopathy (HE) that requires emergency intervention with mechanical ventilation. Conventional mechanical ventilation (CMV) is currently recommended as the gold-standard technique for the treatment of patients with AECOPD and HE. CMV is an invasive form of ventilation that utilizes positive pressure to deliver an air/oxygen mixture to the airways via an endotracheal or tracheostomy tube. It can be delivered through one of several modes, including assist-control ventilation, synchronized intermittent mandatory ventilation, and pressure support (PS) ventilation.[3] Despite the undoubted benefits of CMV in some patients with acute respiratory failure, the mortality can be as high as 40%, and a proportion of these deaths may be attributed to complications associated with CMV and its need for an artificial airway, including excessive cuff pressure requirements, self-extubation, stomal infection and hemorrhage, tracheal stenosis, laryngotracheal injury, and ventilation-associated pneumonia.[4–7]
Noninvasive ventilatory support is an alternative approach to CMV that does not require endotracheal intubation (ETI) or the placement of a tracheostomy tube. There is now good evidence from numerous studies that noninvasive positive-pressure ventilation (NPPV) is an effective intervention in patients with acute respiratory failure, including those with COPD and HE, and has advantages over CMV that include no requirement for ETI, fewer complications such as ventilator-associated pneumonia, pneumothorax, and delirium, shorter hospital stay, and reduced mortality.[8–12] NPPV utilizes positive pressure to deliver air/oxygen to the airways via an interface such as a face mask, nasal mask/plugs, or helmet. Various modalities of NPPV exist, including the application of continuous positive airway pressure throughout the respiratory cycle, or the delivery of bilevel positive airway pressure (BiPAP), that is, 2 different pressure levels according to the respiratory cycle.
However, patients with HE and a depressed cough reflex are unable to efficiently clear copious secretions from their airways, and this can cause failure of NPPV.[10,11] A small number of studies have reported that some noninvasive physiotherapeutic techniques can improve mucus clearance in patients with AECOPD managed with NPPV.[11,13–15] Unfortunately, there are currently no data on the use of these techniques in patients with HE and abundant secretions.[16] One recent study demonstrated the safety and effectiveness of early therapeutic fiberoptic bronchoscopy (FBO) during NPPV,[12] raising the possibility that this strategy might be a viable alternative to CMV in the management of selected patients with COPD within expert units. However, the authors acknowledged several limitations of their study (including the invasive nature of the technique and the applicability of the data only to units with a large expertise in NPPV and FBO).[12] Thus, the development of a simpler approach to clearing airway secretions during NPPV is strongly needed to overcome the obstacles of using NPPV in patients with copious respiratory secretions.
An oropharyngeal airway (OPA) helps to establish a patent airway by preventing the tongue from covering the epiglottis.[17] It is used frequently in emergency care for short-term airway management in unconscious subjects with spontaneous respiration,[18] and to facilitate manual ventilation with a face mask.[19] Importantly, the use of an OPA is not only simple but also allows vacuum aspiration of sputum using a noninvasive and established technique.
We hypothesized that a combination of noninvasive techniques, including repeated suctioning of secretions from an OPA, appropriate patient posture, nebulized inhalation of salbutamol and ambroxol, and close monitoring, could be used within an intensive care unit (ICU) to maintain a clear airway during the first 2 hours of NPPV. The aim of this pilot study was to examine the safety and effectiveness of this treatment strategy in the clearing of airways during NPPV. An additional aim was to determine the outcomes of this strategy when administered (within an ICU) to patients with AECOPD and HE who would not typically be considered appropriate candidates for NPPV because of their inability to remove copious secretions.
2 Materials and methods
2.1 Study design
This prospective cohort study was performed between October 2013 and August 2015 in 2 departments: a 6-bed respiratory ICU (RICU) in the Respiratory Division of the Harrison International Peace Hospital, Hengshui, Hebei, China; and a 25-bed general ICU at the same hospital. The study protocol was approved by the ethics committee of Harrison International Peace Hospital, and informed written consent was obtained from the proxy due to the depressed mental status of the study participants. All included participants in the RICU were treated with CMV, while those in the ICU were treated with early 2-hour NPPV combined with noninvasive techniques to clear mucous secretions.
2.2 Patients
The participants were enrolled consecutively using the following inclusion criteria: a diagnosis of AECOPD was made based exclusively on the clinical presentation of the participant, who complained of an acute change in dyspnea, cough, and/or sputum production that was beyond normal day-to-day variation; assessment of the symptoms was based on the subject's medical history, clinical signs of severity, and laboratory tests[20]; the participant was unable to spontaneously clear his/her airways of excessive secretions (highest score of an arbitrary cough efficiency scale)[21]; arterial blood gas (ABG) analysis (PaCO2 >6.0 kPa [45 mm Hg] and/or pH <7.35) pointed toward a life-threatening episode that needed close monitoring or intensive care[20]; the participant had moderate-to-severe dyspnea with use of accessory muscles and paradoxical abdominal motion[20]; and the Kelly–Matthay scale (KMS) score for encephalopathy was between 3 and 5 (3 = lethargic, but rousable and follows simple commands; 4 = stuporous, i.e., only intermittently follows simple commands even with vigorous attempts to rouse the subject; 5 = comatose, brain stem intact).[22]
The exclusion criteria were as follows: preexisting psychiatric and/or neurological disorders unrelated to HE; upper gastrointestinal bleeding; upper airway obstruction; acute coronary syndromes; tracheostomy or ETI before admission; and need for urgent ETI due to cardiac or respiratory arrest, psychomotor agitation, or severe hemodynamic instability.
2.3 NPPV with early 2-hour strategy to clear secretions
Participants in the ICU were managed using NPPV, with airway management and clearance of secretions performed in the initial 2 hours of NPPV.
NPPV (Flexo ST30 ventilator, Curative Medical Inc, Santa Clara, CA) was delivered in spontaneous/timed mode with positive end-expiratory pressure (PEEP) via a well-fitting oronasal mask (ZS-MZ-A, Zhongshan, Shanghai, China) with the addition of a single-use heated humidifier (G-314001-0, Vadi Medical Technology Co Ltd, Taiwan, China). PS was initially set at 8 to 10 cm H2O and then titrated to achieve an expiratory tidal volume of 6 to 8 mL/kg up to a maximum of 25 cm H2O, depending on the clinical ABG response and the participant's tolerance. PEEP was always set at 3 to 5 cm H2O. Backup respiratory rate (RR) was set at 14 to 18 breaths/min, lower than the participant's spontaneous RR. The fraction of inspired oxygen (FiO2) was adjusted to keep pulse blood oxygen saturation (SpO2) at about 90% to 94%.[10] As far as possible, the participant was treated in a semirecumbent or sitting position (45°C–90°C) during NPPV in order to minimize the possibility of aspiration.
An OPA (GuedelFix airway, VBM Medizintechnik GmbH, Sulz am Neckar, Germany) of appropriate size was selected so that, from an external viewpoint, it extended from the lower tip of the ear to the corner of the closed mouth (Figs. 1 and 2); choosing the correct size was important to ensure that the tongue was held in place without trauma to the pharynx or airway obstruction. To open the participant's mouth, the thumb and the index finger (crossed-finger method) were pushed against the upper and lower teeth near a corner of the mouth. The tip of the OPA was introduced into the participant's mouth (Fig. 3) with the tube lying on the tongue and the airway tip pointing toward the roof of the mouth (to help to keep the tongue from being pushed toward the back of the throat as the airway was inserted). The airway was advanced, and when its tip reached the back of the tongue (past the soft palate), it was rotated 180° so that the tip pointed down toward the throat. If the airway was difficult to insert or rotate, the participant's tongue was gently pulled forward with the fingertips of the hand not holding the airway. The airway was advanced until the flange rested against the lips, and the tongue was held in place so that it did not slide toward the back of the throat.
Figure 1 Oropharyngeal airway.
Figure 2 Selecting an oropharyngeal airway of appropriate size.
Figure 3 Inserting the oropharyngeal airway.
Respiratory secretions were aspirated every 20 to 30 minutes during the initial 2 hours using a suction catheter inserted as deeply as possible into the trachea via the OPA; the participant's back was slapped before aspiration to facilitate the removal of secretions. Preoxygenation was considered if the participant had a clinically important reduction in oxygen saturation with suctioning; subsequently, the FiO2 was decreased in order to maintain the SpO2 at 90% to 94%.
Salbutamol 5 mg (Salamol, GlaxoSmithKline, Brentford, UK) and ambroxol 15 mg (Mucosolvan, Boehringer Ingelheim, Barcelona, Spain) in 2.5 mL normal saline were administered as a nebulized inhalation for 5 minutes (LCV nebulizer, Pari GmbH, Starnberg, Germany) at an oxygen flow rate of 7 L/min.[23] The nebulizer was placed between the leak port and the connection to the participant, and the nebulizer was maintained in a horizontal position during NPPV (Figs. 4 and 5).
Figure 4 Placement of the nebulizer between the leak port and the subject connection.
Figure 5 The nebulizer was maintained in a horizontal position during noninvasive positive-pressure ventilation (NPPV).
All participants received standard medical therapy consisting of controlled oxygen therapy during NPPV-free periods; antibiotics, intravenous doxofylline, corticosteroids, and subcutaneous low-molecular-weight heparin; and therapy for comorbidities if necessary. Nasogastric tubes were inserted only in participants who developed gastric distension. No pharmacological sedation was administered.
The 2-hour strategy of NPPV with aspiration of secretions was considered successful if the KMS had declined by at least 1 point and the pH had increased by at least 0.05 to 0.10 by the end of the initial 2-hour period, as compared to baseline. During the following 12 to 24 hours, continuous NPPV was provided with the participant maintained in a semirecumbent position, secretions aspirated hourly via the OPA, and nebulized inhalation of salbutamol/ambroxol administered every 6 hours. The removal of secretions via the OPA was stopped if the participant was able to clear the secretions spontaneously.
NPPV was administered intermittently once the clinical status, KMS score, and ABGs had improved substantially. PS was reduced progressively until a level of ≤8 to 10 cm H2O was reached. NPPV weaning was considered successful when all the following criteria had been met for longer than 24 hours while breathing with oxygen (FiO2 0.28): pH >7.35, SpO2 >90%, RR <30 breaths/min, KMS score 1, and stable hemodynamic status.[24] Noninvasive home mechanical ventilation (HMV) via a facial or nasal mask was considered if the subject remained partially dependent on NPPV (≥8 hours/d) after 10 days.[10]
NPPV was considered to have failed if at least 1 of the following criteria was met and ETI was promptly available: cardiac arrest or severe hemodynamic instability, respiratory arrest or gasping, mask intolerance, difficulty in clearing bronchial secretions, and worsening of ABGs or sensorium level during NPPV.[25]
2.4 Conventional mechanical ventilation
Participants who received CMV were enrolled using the same inclusion criteria as those for patients administered NPPV. Intubation was carried out after admission to the RICU without NPPV being first attempted.
The standard therapeutic protocol was the same as that for the NPPV group except that the participants were sedated at the time of intubation with daily interruption of sedation (2 mg/kg propofol intravenously followed by a continuous infusion at 0.5–3 mg/kg/h, usually for 24–36 hours).[10] CMV was delivered via a ventilator (Puritan Bennett 840, Covidien, Dublin, Ireland) in synchronized intermittent mandatory ventilation + PS mode (target tidal volume 6–8 mL/kg; backup RR 10–15 breaths/min; FiO2 0.30–0.45; PEEP 3–5 cm H2O; PS 8–14 cm H2O, or platform pressure <30 cm H2O).[26]
Extubation was performed if the subject met the same criteria as those used for the NPPV group. If the subject was still intubated and ventilated after 12 days, tracheostomy was performed according to the judgment of the physician in charge. If the subject and/or proxy refused tracheostomy, CMV was considered to have failed. HMV via tracheostomy was considered if the subject was still ventilator-dependent after 30 days.[27]
2.5 Data collection
In addition to KMS score and ABG analysis, the following additional data were collected: age, gender, lung function in the stable phase within the previous 6 months, body mass index, Acute Physiology and Chronic Health Evaluation II score, hospital stay before mechanical ventilation, number of invasive devices, PS, need for de novo long-term oxygen therapy, and HMV.
The primary end points were as follows: the safety (need for urgent ETI) and effectiveness (changes in ABGs and KMS) of the secretion clearing strategy within the first 2 hours of NPPV, and the rate of major complications,[27] especially septic complications and nosocomial pneumonia (including pulmonary aspiration) that were diagnosed using strict criteria.[28,29] The secondary end points were as follows: in-hospital mortality, 1-year mortality, tracheostomy, duration of mechanical ventilation, and length of hospital stay.
2.6 Statistical analysis
The Shapiro–Wilk test was used to verify whether all recorded variables were normally distributed (P > 0.05). Continuous data are expressed as the mean ± standard deviation if distributed normally or as median (interquartile range) if not. Continuous variables were compared with the 2-tailed unpaired Student t test (parametric data) or the Mann–Whitney U test (nonparametric data). Categorical data were compared using the χ2 or, when appropriate, Fisher exact test. The mean ABG data at different time points were compared with repeated measures analysis of variance. The sensorium level between baseline and 2 hours in the NPPV group was compared using the paired Student t test. A P value <0.05 was considered statistically significant. Differences in the probability of remaining on mechanical ventilation over 30 days between the 2 groups were investigated by means of Kaplan–Meier curves.
3 Results
3.1 Baseline characteristics
Of 186 patients with AECOPD screened for inclusion in the study, 164 were included in the analysis (90 in the CMV group and 74 in the NPPV group). There were no significant differences between the 2 groups in any of the baseline characteristics (Table 1).
Table 1 Characteristics of the NPPV and CMV groups.
3.2 ABGs, sensorium level, and other indexes during the first 2 hours of mechanical ventilation
Compared to baseline, the ABGs improved significantly in both groups after 2 hours of mechanical ventilation, but no significant differences were observed in pH, PaO2/FiO2, and PaCO2 between the NPPV and CMV groups within the initial 2-hour period (P = 0.124, 0.095, and 0.740, respectively; Fig. 6). The sensorium level significantly improved within 2 hours in the NPPV group (P < 0.001; Fig. 7), but was not evaluated in the CMV group due to the use of sedation.
Figure 6 Comparisons of the pH, PaO2/FiO2, and PaCO2 values between the noninvasive positive-pressure ventilation (NPPV) and conventional mechanical ventilation (CMV) groups within the initial 2 hours of ventilation (P = 0.124, 0.095, and 0.740, respectively; repeated measures analysis). Values are expressed as the mean ± SD. FiO2 = fraction of inspired oxygen, PaCO2 = partial pressure of arterial carbon dioxide, PaO2 = partial pressure of arterial oxygen; SD = standard deviation.
Figure 7 Kelly–Matthay scale (KMS) score at baseline, and 1 and 2 hours in the noninvasive positive-pressure ventilation (NPPV) group. Values are expressed as the mean ± SD. Value at 2 hours versus that at baseline, P < 0.01. MV = mechanical ventilation, SD = standard deviation.
3.3 Adverse reactions and complications
Subjects receiving CMV had a higher complication rate than those receiving NPPV due to a greater occurrence of nosocomial infections and use of more invasive devices.
3.4 Outcome measures
Hospital mortality was lower in the NPPV group than in the CMV group, but 1-year mortality rate, de novo initiations of long-term oxygen therapy, and HMV rate were similar between the 2 groups (Table 2).
Table 2 Prognostic indicators in NPPV and CMV groups.
NPPV failed in 12 of 74 (16%) participants after a total of 13.5 ± 5.9 days of ventilation due to worsening of ABGs (n = 5), retention of secretions (n = 3), mask intolerance (n = 2), or worsening level of consciousness (n = 2). Nasogastric tubes were used in 33 participants for gastric distension that proved to be fully reversible. Mild facial skin erythema occurred in 22 participants. Four participants were not intubated after NPPV failure because ETI was refused, and these participants died from septic shock (n = 2) and cardiac arrest (n = 2). The causes of in-hospital death in the CMV group were septic shock (n = 8), cardiovascular complications (n = 6), and acute kidney injury (n = 2). Three subjects unweaned from CMV received tracheostomy and HMV treatment.
There were no differences between the 2 groups in the overall duration of mechanical ventilation and the length of hospital stay (Table 2). However, Kaplan–Meier analysis showed that the percentage of subjects not weaned from mechanical ventilation within 30 days was significantly lower in the NPPV group than in the CMV group (log rank 9.635, P = 0.002; Fig. 8).
Figure 8 Kaplan–Meier curves showing that the percentage of participants unweaned from mechanical ventilation (MV) at 30 days was significantly lower in noninvasive positive-pressure ventilation (NPPV) group than in the conventional mechanical ventilation (CMV) group (log rank 9.635, P = 0.002). Participants who died or refused further treatment during MV were considered unweaned from the ventilator.
4 Discussion
The main finding of the present study was that noninvasive techniques to clear respiratory secretions during the first 2 hours of NPPV were safe and effective in patients with AECOPD and HE. Indeed, 2 hours of NPPV with clearance of secretions significantly improved KMS score and ABGs with no complications. Although the improvements in pH, PaO2/FiO2, and PaCO2, and the duration of hospitalization, were similar in the NPPV and CMV groups, the period required to wean from mechanical ventilation was significantly shorter in the NPPV group. Moreover, the NPPV group had a lower rate of nosocomial infection complications and lower hospital mortality than the CMV group. We conclude that NPPV in combination with a noninvasive strategy to clear respiratory secretions during the first 2 hours may be superior to CMV in the treatment of patients with AECOPD complicated by HE.
Although the potential advantages of NPPV over CMV are well documented,[8–12] noninvasive ventilation has generally not been recommended for patients with altered consciousness syndrome due to poor patient compliance, the accumulation of secretions secondary to a depressed cough reflex, and the risk of aspiration pneumonia if the airways are not protected.[30] Indeed, early failure of NPPV is most often attributed to a weak cough reflex, excessive secretions, HE, intolerance, agitation, and patient–ventilator asynchrony.[31] For these reasons, only a small number of clinical studies have assessed the use of NPPV in patients with AECOPD and HE. Duenas-Pareja et al reported that 78% of patients treated with BiPAP–NPPV showed a reversal of coma and an improvement in pH within 48 hours, and that 69% survived.[9] Zhu et al found that NPPV was successful in 72% of their patients with AECOPD and HE, with a survival rate of 86%; the main cause of failure was excessive airway secretions.[32] Briones Claudett et al have also observed that BiPAP–NPPV has utility in patients with AECOPD and HE.[33] Very few studies have directly compared NPPV with CMV in patients with AECOPD and HE. Scala et al determined that NPPV (without specific interventions to clear respiratory secretions) was associated with a lower rate of complications (mainly due to fewer cases of nosocomial infection or sepsis) and a shorter ventilation time than CMV, although the 2 approaches did not differ in terms of ABGs, in-hospital mortality, 1-year mortality, and tracheostomy rates.[10] Moreover, a recent meta-analysis found that, compared with CMV, noninvasive ventilation significantly reduced the mortality rate, intubation rate, rate of ventilation-related complications, and duration of ventilation.[34] Although these data already support the use of NPPV in patients with HE due to AECOPD, the ability to clear respiratory secretions during NPPV in a noninvasive manner would likely make this an even more attractive option in this clinical setting.
As described earlier, a weak cough reflex leading to inefficient clearance of excessive airway secretions is a common cause of immediate NPPV failure,[35,36] and is considered a relative contraindication for NPPV, especially in patients with impaired consciousness and depressed cough.[37,38] NPPV does not allow direct access to the airways, which is a disadvantage in terms of the removal of secretions, although some investigations have indicated that specific “manual” or “mechanical” physiotherapeutic techniques may improve mucociliary clearance during NPPV and that NPPV can still be used in these circumstances.[13,14] Interestingly, a study by Scala et al reported the successful use of FBO to aspirate airway secretions during NPPV in patients with AECOPD and HE.[12] In their study, 2 hours of NPPV with FBO significantly improved ABGs, KMS score, and cough efficiency score without FBO-related complications, avoiding the need for intubation in 80% of patients. Furthermore, NPPV with FBO was associated with lower rates of overall and septic complications than CMV, and there were no differences between groups in ABG improvement, hospital mortality, length of hospital stay, and duration of ventilation. Nonetheless, FBO is an invasive technique, and the authors acknowledged that the combination of NPPV with FBO would be limited to units with expertise in these techniques. This highlights the need for a noninvasive method of clearing respiratory secretions during NPPV.
A novel aspect of the present study is that it used an OPA to facilitate the clearance of secretions during NPPV. The OPA helped in the establishment of a patent airway by preventing the tongue from covering the epiglottis, and facilitated manual ventilation using a face mask. In our study, the early use of an OPA permitted the effective clearance of mucus and induced a cough reflex. Therefore, this may represent a useful clearance technique in subjects with copious secretions and a depressed cough reflex.[19,39] We used a combination of techniques to maximize the clearance of secretions during NPPV. First, the patient was maintained in an appropriate body position to allow the removal of secretions and avoid aspiration. Studies using radioactive-labeled enteral feeding have shown that cumulative endotracheal counts were higher for participants in the completely supine position (0°C) than in those in the semirecumbent position (45°C), suggesting that aspiration might be decreased by semirecumbent positioning.[40] Second, we administered nebulized salbutamol and ambroxol. Patients with acute or acute-on-chronic respiratory failure who receive NPPV often require inhaled bronchodilators for relief of airway obstruction. Several investigations have employed in vitro models to determine the optimal techniques for aerosol delivery in subjects receiving NPPV, and have observed significant bronchodilator responses after albuterol administration with a jet nebulizer or pressurized metered-dose inhaler in stable subjects during NPPV with a mask.[41–44] Furthermore, aerosol delivery was highest when the nebulizer was close to the subject (between the leak port and the subject connection).[42,45] In our clinical experience, patients receiving inhaled therapy during NPPV show a greater improvement in oxygen saturation and breathlessness than those receiving nebulized drug alone.
There are several aspects of our strategy that need to be considered when our results are applied to clinical practice. First, unlike FBO, the use of an OPA to facilitate the clearance of secretions is a noninvasive, simple technique that would be straightforward to implement in other hospitals. Second, it was notable that our study showed a higher success rate than other recent reports.[10,12] This may have been because our participants were patients with severe AECOPD in an ICU, where they are likely to receive more intensive care and closer observation, and where the means to promptly intubate the patient if necessary are readily at hand. Third, it should be noted that 3 participants could not cooperate with NPPV because of agitation, and required restraining until they became more alert during NPPV. Fourth, only 2 cases of NPPV failure were induced by mask intolerance, a rate lower than that of a previous study.[10] This good level of compliance in patients with HE may have been because the masks were manufactured in China according to the facial features of Chinese people.
The present study has several limitations. First, this was not a randomized controlled trial, which may have biased the results in favor of the therapy under investigation.[10] However, the cases (NPPV) and controls (CMV) were prospectively enrolled during the same period, using the same inclusion and exclusion criteria. Despite this limitation, it is accepted that well-designed observational studies can yield reliable results provided that the cases and controls are well balanced by careful matching, and the interference of confounding factors is minimized.[46] In this study, the cases were similar to the controls not only for the matching criteria but also for other historical/clinical/physiological features. Second, this was a single-center study, and hence it is not known whether our findings can be generalized. Third, the hospital setting of the CMV (RICU) and NPPV (ICU) groups differed, which potentially may have introduced bias into the study. Fourth, it would have been instructive to include an additional comparator group consisting of participants treated with NPPV alone (i.e., not in combination with OPA-facilitated clearance of secretions); this would have allowed the specific advantages of OPA use and mucus clearance to be determined.
In conclusion, the use of an OPA and suction aspiration, in combination with appropriate positioning of the patient and nebulized inhalation of salbutamol/ambroxol, was a feasible, simple, safe, and effective method for clearing respiratory secretions during the first 2 hours of NPPV in patients in ICU with AECOPD and HE. Moreover, compared with CMV, this innovative strategy reduced the risks of nosocomial infection, requirement for intubation, and hospital mortality, and showed superior results in terms of weaning from ventilation. Therefore, we propose that this novel NPPV strategy might be a successful alternative to CMV in selected patients with AECOPD in the ICU, where there is prompt access to ETI if needed. Large-scale, randomized controlled trials comparing our NPPV strategy to CMV in patients with AECOPD and HE are merited to confirm our results.
Acknowledgments
We would like to thank all the data collectors of Harrison International Peace Hospital. In addition, we thank Prof. Xiao-xue Ke from Southwest University for offering feedback and suggestions on this manuscript.
Abbreviations: ABG = arterial blood gas, AECOPD = acute exacerbation of chronic obstructive pulmonary disease, BiPAP = bilevel positive airway pressure, CMV = conventional mechanical ventilation, COPD = chronic obstructive pulmonary disease, ETI = endotracheal intubation, FBO = fiberoptic bronchoscopy, HE = hypercapnic encephalopathy, HMV = home mechanical ventilation, ICU = intensive care unit, KMS = Kelly–Matthay scale, NPPV = noninvasive positive-pressure ventilation, OPA = oropharyngeal airway, PEEP = positive end-expiratory pressure, PS = pressure support, RICU = respiratory ICU, RR = respiratory rate.
The authors have no funding and conflicts of interest to disclose.
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Medicine (Baltimore)Medicine (Baltimore)MEDIMedicine0025-79741536-5964Wolters Kluwer Health 28328826MD-D-16-0354710.1097/MD.0000000000006374063746900Research ArticleObservational StudyEffect of adductor canal block on medial compartment knee pain in patients with knee osteoarthritis Retrospective comparative studyLee Doo-Hyung MD, PhDaLee Michael Y. MD, MHAbKwack Kyu-Sung MD, PhDcYoon Seung-Hyun MD, PhDd∗Gharaei. Helen a Department of Orthopedic Surgery, Ajou University School of Medicine, Suwon, Republic of Koreab Department of Physical Medicine and Rehabilitation (M.Y. Lee), University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC.c Department of Radiologyd Department of Physical Medicine and rehabilitation, Ajou University School of Medicine, Suwon, Republic of Korea.∗ Correspondence: Seung-Hyun Yoon, Department of Physical Medicine and Rehabilitation, Ajou University School of Medicine, Worldcup-ro 164, Yeongtong-gu, Suwon 16499, Republic of Korea (e-mail: yoonsh@ajou.ac.kr).3 2017 24 3 2017 96 12 e637419 5 2016 20 2 2017 21 2 2017 Copyright © 2017 the Author(s). Published by Wolters Kluwer Health, Inc.2017This is an open access article distributed under the terms of the Creative Commons Attribution-Non Commercial-No Derivatives License 4.0 (CCBY-NC-ND), where it is permissible to download and share the work provided it is properly cited. The work cannot be changed in any way or used commercially without permission from the journal. http://creativecommons.org/licenses/by-nc-nd/4.0Abstract
Knee osteoarthritis (KOA) is a common disease in middle-aged and elderly people. Pain is the chief complaint of symptomatic KOA and a leading cause of chronic disability, which is most often found in medial knees. The aim of this study is to evaluate the efficacy of pain relief and functional improvement in KOA patients treated with ultrasound-guided adductor canal block (ACB).
This is a 3-month retrospective case-controlled comparative study. Two hundred patients with anteromedial knee pain owing to KOA that was unresponsive to 3-month long conservative treatments. Ninety-two patients received ACB with 9 mL of 1% of lidocaine and 1 mL of 10 mg triamcinolone acetonide (ACB group), and 108 continued conservative treatments (control group). The main outcome measure was visual analog scale (VAS) of the average knee pain level for the past one week. Secondary outcomes were the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), the timed up and go test, numbers of analgesic ingestion per day, and opioid consumption per day.
During the 3-month follow-up, 86 patients in ACB group and 92 in control group were analyzed. There was no significant difference, with the exception of the duration of symptoms, between the 2 groups in age, sex, body mass index, and Kellgren-Lawrence grade. Repeated-measures analysis of variance and post hoc tests showed improvement of VAS (at month 1), WOMAC (at month 1), and opioid consumption per day (at month 1 and 2) in ACB group. No adverse events were reported.
To our knowledge, this is the first study to assess the efficacy of ACB for patients with KOA. ACB is an effective and safe treatment and can be an option for patients who are either unresponsive or unable to take analgesics.
Keywords
arthritisknee jointknee painnerve blockosteoarthritisOPEN-ACCESSTRUE
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1 Introduction
Knee osteoarthritis (KOA) is a common disease in middle-aged and elderly people. Pain is the chief complaint of symptomatic KOA and a leading cause of chronic disability [1] which is most often found in medial knees.[2,3] Management of patients with knee pain requires a combination of pharmacological and nonpharmacological treatments, including surgical interventions when necessary.[4]Pharmacological treatments would often be the first option, and if pain still continues, rehabilitation including exercises and physical therapies may be added as part of nonpharmacological interventions, on top of pharmacological treatments.[5]
The saphenous nerve is the pure sensory branch of the femoral nerve. It runs laterally to the femoral artery, and then enters the adductor canal (Hunter canal, or sartorius canal) where it crosses in front of the femoral artery. The saphenous nerve provides an extensive cutaneous innervation over the anteromedial side of the knee, lower leg, and foot.[6] Saphenous nerve block, used in the leg during the surgical anesthesia,[7] can help increase the success rate of saphenous nerve block in the adductor canal (adductor canal block, ACB) when performed with an ultrasound-guided approach.[8] Recent studies have reported the efficacy of ACB in the management of analgesia following total knee arthroplasty [9–12] and post-meniscectomy.[13] In addition, the administration of ACB may be accomplished also as a single-shot injection after total knee arthroplasty.[12,14] However, no study has yet reported the efficacy of ACB for KOA. The aim of this study is to evaluate the efficacy of ultrasound-guided ACB as a therapeutic option for refractory anteromedial knee pain owing to KOA.
2 Methods
2.1 Study design and subjects
This is a retrospective case-controlled comparative study. After the approval of the institutional review board, medical records of 292 patients who were diagnosed with KOA with anteromedial pain between January 2010 and April 2015 were reviewed. They were outpatients at the rehabilitation and orthopedic clinics of the university hospital. All patients underwent a standardized history-taking, physical examination, blood test, and knee x-rays. Inclusion criteria were patients diagnosed as having symptomatic bilateral KOA according to the criteria of the American College of Rheumatology;[15] grade of Kellgren–Lawrence grading scale (a scoring tool used to assess the severity of knee osteoarthritis on a plain radiograph)[16] 2 to 4 of KOA; age 50 years and above; reporting at least 6-month duration of symptoms; having matching symptom (anteromedial knee pain) and simple x-ray findings with KOA; and with direct tenderness on anteromedial aspect of the knee owing to KOA. Exclusion criteria were the presence of other obvious knee pathology, such as fracture, or rheumatic diseases; referred pain from the lower back suggestive of lumbar radiculopathy; previous surgery to the knee; knee synovitis; and abnormal sensory perception suggestive of injury or entrapment of saphenous nerve.
Two hundred ninety-two patients were diagnosed to have KOA and underwent conservative treatment for at least 3 months before the ACB (Fig. 1). We prescribed analgesics including acetaminophen, nonsteroidal anti-inflammatory drugs, tricyclic antidepressant, selective serotonin and norepinephrine reuptake inhibitor, tramadol, and opioids. Acetaminophen was prescribed for first-line use, with nonsteroidal anti-inflammatory drugs and opioids as second and third lines of treatment according to the guidelines.[5,17] When pain mitigated, the reverse order was applied to reduce the dosage. Patients had institutional flexibility and strengthening exercise of quadriceps with physical therapists 1 or 2 times a week for 4 to 8 weeks, and were educated to carry out the same exercise at home. Patients who could not accommodate regular exercise at the hospital were given educational leaflets and instruction by physical therapists at each outpatient follow-up. When a patient entered the inflammatory phase of osteoarthritis such as increased fluid in the joint, ultrasonography-guided intra-articular corticosteroid injection with triamcinolone acetonide 20 mg was administered.
Figure 1 Flow diagram indicating progress of subjects through the study.ACB = adductor canal block.
If despite the conservative treatment, a patient continued to complain about knee pains with score ≥4 on a visual analog scale (VAS) of the average knee pain level for the past 1 week, we recommended ACB explaining also its indication and complications. Patients were free to choose either the ACB or other treatment options. Patients were given a choice to unilateral or bilateral injection depending on the level of pain. Among 200 patients with refractory KOA, 92 opted for ACB (ACB group) and 108 for conservative treatments (control group) including analgesics and exercise.
2.2 ACB
The patients in the ACB group received an ultrasound-guided single-shot ACB, based on earlier studies.[18,19] ACB was performed at mid-thigh (midpoint between the knee and the inguinal crease) by the lead author with ultrasound equipment (Logiq P6, GE Healthcare, Buckinghamshire, UK) using a 10 to 13 Hz high-frequency linear ultrasound transducer which was placed transverse to the longitudinal axis of the leg. Underneath the sartorius muscle, the saphenous nerve was identified in a short axis view as it descends lateral to the femoral artery in the adductor canal. The lead author injected 9 mL of 1% of lidocaine and 1 mL of 10 mg triamcinolone acetonide with a 23-gauge 6-cm long needle.
2.3 Outcome measurements
VAS for knee pain intensity, the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), the timed up and go test, and numbers of analgesic ingestion per day, and opioid consumption per day were compared for pre-, and 1, 2, and 3 months post-injection. All outcome measurements were evaluated by the lead author. The primary outcome measure was VAS of the average knee pain level for the past 1 week. Patients answered the question “With respect to the worst pain you have experienced in your life, what was the average level of your knee pain in the past one week?? by placing a mark somewhere along the 10-cm horizontal line between 2 end-points (left: “No pain" and right: “the worst imaginable pain." WOMAC is a self-reporting questionnaire for patients with KOA, which consists of 24 items that are divided into 3 subscales: pain (5 items), stiffness (2 items), and physical function (17 items).[20] The timed up and go test is a reliable test with adequate minimal detectable change for clinical use in individuals with KOA.[21,22] Numbers of analgesic ingestion per day were measured based on the average number of analgesics patients have taken per day during the past 1 week. Opioid consumption per day is the past 1 week's average value of opioids consumed by patients per day, which has been converted to the morphine equivalent dose.
2.4 Statistical analysis
After a normality test, we compared 2 groups in terms of age, sex, duration of symptoms, Kellgren-Lawrence grade, and body mass index by performing independent t- or χ2 analysis. The effect of injection during 3 months was evaluated with repeated-measures analysis of variance. If the repeated-measures analysis of variance for group-by-time interaction was significant, post hoc tests (Bonferroni) of between-group comparison were conducted. The P value was adjusted using the Bonferroni method. Significance was accepted for P values of <0.05. All these analyses were performed using SPSS statistical software, version 22 (IBM, Armonk, NY).
3 Results
Out of a total of 200 refractory KOA patients, 92 received ACB and 108 current conservative treatments (Fig. 1). Of them, respectively 86 and 92 patients were included in the final analysis. Among the ACB group, 70 patients (81.4%) received bilateral and 16 (18.6%) unilateral ACB injection. Table 1 lists the baseline characteristics of the study subjects. There were no statistical differences between the 2 groups in terms of age, sex, body mass index, and Kellgren-Lawrence grade, except for the duration of symptoms which lasted longer in the ACB group (8.1 ± 4.4 vs. 6.8 ± 4.1 years). Table 2 shows the changes of outcome measurements of ACB and control groups. Repeated-measures analysis of variance showed significant effect of time in all outcome measurements (P < 0.001). This means that compared to pretreatment, all outcome measures improved significantly in both groups with time. Group-by-time interactions were significant for VAS, WOMAC, and opioid consumption per day between groups (P < 0.001). Post hoc tests for between-group comparisons revealed that there are significant differences in VAS and WOMAC at month 1, and opioid consumption per day at month 1 and 2. There were no adverse events reported such as bleeding, infection, cellulitis, or weakness.
Table 1 Baseline characteristics of patients.
Table 2 Changes of outcome measurements.
4 Discussion
ACB has often been used to control pain after the anesthesia and operation of the lower leg[7,9–12,14] and has been reported to be effective on knee pains caused by saphenous nerve neuropathy and postmeniscectomy pain.[13,23] To our best knowledge, this is the first study to evaluate the efficacy of ACB in KOA. In this 3-month follow-up study, ACB was used to treat patients who had anteromedial knee pain owing to KOA but failed 3-month-long conservative treatments. The ACB group showed improvement in VAS (at month 1), WOMAC (at month 1), and opioid consumption per day (at month 1 and 2), compared to the control group. KOA is very common and the medial compartment is affected most frequently than other areas.[2,3] ACB is easily performed at the outpatient clinic and can reduce pain up to at least 1 month for patients with KOA who continue to show no response to analgesics.
Adductor canal is an aponeurotic tunnel in the middle third of the thigh composed medially of the adductor longus, laterally of the vast us medialis, and interiorly of the sartorius and the subsartorial fascia. ACB blocks the largest sensory contributions from the femoral nerve to the knee, the saphenous nerve.[10,24] In addition to the saphenous nerve, the adductor canal contains the nerve to the vastus medialis, the medial femoral cutaneous nerve, the medial retinacular nerve, and the articular branches from the posterior division of obturator nerve which enters the distal part of the canal. Except for the nerve to the vastus medialis, these branches have a sole sensory function, and most of them play a major role in the sensory innervation of the knee region. Many trials have recently hypothesized that administration of local anesthetic into the ACB could be a useful option for postoperative analgesia after total knee arthroplasty.[9–12] Since KOA is a disease of the entire knee joint, the cause of knee pain can origin not only from degenerative changes of cartilages and bones, such as cartilage wearing, sclerosis of subchondral bone, and osteophytes, but also from tears and subluxation of menisci, sprain of ligaments, tendinitis, bursitis, and synovitis.[1,25–27] As part of its mechanism, ACB is thought to interrupt the pain signal, which originates from various lesions of KOA.
The saphenous nerve departs from the adductor canal in the distal thigh, piercing the fascia between the sartorius and gracilis muscles to become subcutaneous.[30] From this point, the saphenous nerve is first divided distally into 2 branches, sartorial and infrapatellar,[28,29] and then again into multiple small subcutaneous branches. This makes it hard to identify the nerve in more distal locations. In a cadaveric study, the authors found that the saphenous nerve divides into 2 branches from outside the adductor canal at a mean of 2.7 cm proximal to the base of the patella. They reported the block at this location to be successful.[8] In the present study, we blocked the saphenous nerve in the middle of the adductor canal. Ultrasonography was used to identify the entry point of the needle, on average 10 cm proximal to the knee crease. This is an ideal location to block the nerve while using the femoral artery as a landmark. It is also proximal enough to ensure the blocking of both main branches, sartorial and infrapatellar.[18]
Although no difference was found between the 2 groups in terms of the number of analgesic (opioids included) ingestion per day, the ACB group was found to have consumed less opioids per day in month 1 and 2. The difference came from the fact that we had reduced the opioids first among other prescribed analgesics when pain resided and educated the patients to switch to acetaminophen or nonsteroidal anti-inflammatory drugs according to the treatment guidelines.[5,17] Therefore, it was possible for opioid consumption to go down but not the total number of analgesic intake. Although claiming the long-term effect of a single round of ACB in lowering the opioid dosage may be farfetched, there is a clear advantage of ACB in reducing the usage of opioid at least during the first 2 months. Taking into account the common adverse events of opioids that can occur in elderly patients (cognitive impairment, delirium related falls and fractures, depression, cardiovascular events, and pneumonia),[31,32] it may be possible to consider a combined therapy of ACB over additional opioid intake for patients who complain transient acute pain.
We used 10 mL of anesthetic for ACB in this study. The volume of anesthetic that is going to be used needs to be considered as one of the factors impacting the analgesia and side effects of ACB. Although not enough of the anesthetic may result in an insufficient analgesic effect, too much can lead to an undesirable anesthesia or weakness owing to the blocking of the femoral or sciatic nerves, as the adductor canal is connected proximally to the femoral triangle and extended to the adductor hiatus to distally connect with the popliteal fossa.[33,34] Previous trials that administered ACB after a knee surgery have used 10 to 30 mL.[10,13,35] ACBs that used volume of 20 mL have reported sufficient pain relief while at the same time finding little or no weakness owing to femoral nerve blockades.[35–37] However, recent studies have reported that even a volume of <20 mL may affect the femoral or sciatic nerve or branches. In one cadaveric study, 15 mL of injectate that was administered into the adductor canal spread proximally to the femoral triangle and distally to the adductor hiatus.[34] And the results of a study that evaluated the electromyographic activity of vastus medialis and lateralis and muscle weakness of quadriceps femoirs by administering 10, 20, and 30 mL of 1% lidocaines to 20 volunteers showed a strong association between volume and vastus medialis effects. A volume of 30 mL resulted in an affection in all subjects, a volume of 20 mL resulted in an affection in 84% of the subjects, whereas a volume of 10 mL only resulted in an affection in 35% of the subjects.[38] We asked patients whether they had any weakness of quadriceps before ACB and upon follow-up; however, none of the patient reported any weakness. Still, as no quadricep muscle power or electromyographic activity was used for the measurement, we were not able to identify whether the volume used had impacted femoral or scitic nerves. As there is no consensus on how different volumes affect analgesic effect and quadriceps weakness, patients should be monitored for motor strength to reduce the risk of fall.
The greatest limitation of this study lies in the fact that it is a retrospective study and that the group allocation was not randomized. Patients chose to take the therapy according to their own will, and no randomization process was involved. Nonetheless, it has relatively low drop-out rate (11.0% in total), a large sample size (N = 178), enough follow-up period (3 months) to monitor the effect of ACB, and consistent baseline characteristics (age, sex, body mass index, and Kellgren-Lawrence grade) across both groups compared. It also includes at least 3 rounds of follow-ups (at month 1, 2, and 3) after ACB to monitor whether other treatments have been received, which was a part of the effort to reduce bias as much as possible. Second, the aim of this study was to evaluate the changes in the long-term evaluation (1, 2, and 3 months) of pain and function of ACB; therefore, the outcome measurement immediately after ACB was not measured. However, the fact that sensory evaluation was not performed to confirm the success of sensory blockade can be a limitation. Third, not only are there many factors impacting pain including psychological and environmental factors, drugs, stress, and concomitant diseases, but also great changes that take place between these factors with time. In an effort to take these into consideration, we tried to identify mid-term changes in pain rather than immediate changes claimed on the day of the follow-up visit. VAS of the average knee pain level for the past 1 week was therefore used as our tool. However, this tool may have a greater recall bias than the ordinary VAS.
In conclusion, this study looked into the possibility of ACB as an alternative treatment for anteromedial knee pain owing to KOA. Although a palliative treatment, and not one that stops the progression of the disease or changes its natural course, ACB can be an option for patients with refractory KOA who cannot take or are not responsive to analgesics. However, to prove the efficacy of ACB, further studies on prospective randomized controlled trials would be needed to overcome the limitations mentioned in the discussions.
Acknowledgment
The authors thank Aeree Park, MA, for English translation of Korean manuscript.
Abbreviations: ACB = adductor canal block, KOA = knee osteoarthritis, VAS = visual analogue scale, WOMAC = the Western Ontario and McMaster Universities Osteoarthritis Index.
The authors report no conflicts of interest.
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Medicine (Baltimore)Medicine (Baltimore)MEDIMedicine0025-79741536-5964Wolters Kluwer Health 28328831MD-D-16-0542310.1097/MD.0000000000006393063934300Research ArticleObservational StudyExpression characteristics of proteins of IGF-1R, p-Akt, and survivin in papillary thyroid carcinoma patients with type 2 diabetes mellitus Yan Yuerong MDaHu Fengqiu MDaWu Weilu MDbMa Ruiting MDaHuang Hui PhDa∗Volti. Giovanni Li a Department of Endocrinology and Metabolismb Department of Pathology, West China Hospital, Sichuan University, Chengdu, Sichuan, China.∗ Correspondence: Hui Huang, Department of Endocrinology and Metabolism, West China Hospital, Sichuan University, No. 37, Guoxue lane, Chengdu, Sichuan 610041, China (e-mail: sansan1880@126.com).3 2017 24 3 2017 96 12 e639326 8 2016 13 12 2016 23 2 2017 Copyright © 2017 the Author(s). Published by Wolters Kluwer Health, Inc.2017This is an open access article distributed under the terms of the Creative Commons Attribution-Non Commercial-No Derivatives License 4.0 (CCBY-NC-ND), where it is permissible to download and share the work provided it is properly cited. The work cannot be changed in any way or used commercially without permission from the journal. http://creativecommons.org/licenses/by-nc-nd/4.0Abstract
Type 2 diabetes mellitus (T2DM) is related to increased risk of papillary thyroid carcinoma (PTC). Insulin-like growth factor-1 receptor (IGF-1R) is increased in patients with T2DM. The increased IGF-1R may be responsible for the development of PTC. In this study, we investigated the expression of phosphorylation of Akt (p-Akt)/survivin pathway activated by IGF-1R in PTC subjects with and without diabetes.
Clinicopathological data of 20 PTC patients with T2DM were retrospectively analyzed and compared with those of 21 PTC subjects without diabetes. Meanwhile, IGF-1R, p-Akt, and survivin expressions of PTC tissues were detected by immunohistochemical staining.
The immunohistochemical results found that the expression level of IGF-1R was significantly higher in diabetic PTC patients than that in nondiabetic PTC patients (P < 0.05). However, no significant differences of p-Akt and survivin expression were found between PTC patients with T2DM and PTC patients without T2DM. In addition, among 20 PTC patients with T2DM, subgroup analysis showed that the ratio of tumor size >10 mm was significantly higher in IGF-1R moderate to strong expression group than that in IGF-1R negative to weak expression group (P < 0.05).
IGF-1R expression level was higher in PTC patients with T2DM, and the increased IGF-1R expression was associated with lager tumor size. IGF-1R may play an important role in carcinogenesis and tumor growth in PTC patients with T2DM.
Keywords
IGF-1Rp-Aktpapillary thyroid carcinomasurvivintype 2 diabetes mellitusOPEN-ACCESSTRUE
==== Body
1 Introduction
During the past several decades, an increasing incidence of papillary thyroid carcinoma (PTC) has been observed in several countries. A study conducted in 5 continents reported that the average increase of incidence rate of thyroid cancer is 48.0% among males and 66.7% among females over the 30-year period (1973–2002).[1] In China, the incidence rate of thyroid cancer is rising by about 14.5% per year.[2] The general applications of thyroid ultrasonography and some other factors may contribute to the increased incidence and prevalence of thyroid cancer.[3]
Meanwhile, a parallel secular rise in type 2 diabetes mellitus (T2DM) prevalence and morbidity has been reported. The World Health Organization predicted that in 2030 the total diabetic population would rise to 300 million.[4] Furthermore, higher risks and mortalities of a variety of cancers have been reported in diabetes.[4,5] Similarly, a higher risk of thyroid carcinoma is found in T2DM females than in the general females.[6] A 10-year prospective study in America reported that the risk of thyroid carcinoma increases 25% among diabetics.[7] It is well known that insulin resistance and hyperinsulinemia is the key feature of T2DM, while insulin resistance and hyperinsulinemia is associated with cancers, for example, breast and colon carcinoma.[5] However, the exact biological mechanisms underlying the carcinogenic effects of T2DM in PTC are not fully investigated and reported. We speculated that there may be distinctive pathogenesis of thyroid carcinoma in patients with T2DM, which is different from that in those without T2DM.
The insulin-like growth factor-1 receptor (IGF-1R) plays important roles in insulin resistance and hyperinsulinemia in diabetes, and its expression is significantly higher in lung cancer with T2DM.[8] IGF-1R activation by tyrosine phosphorylation of β-subunit results in activation of phosphatidylinositol 3-kinase (PI3K)/Akt and RAS/mitogen-activated protein kinase (MAPK) pathways that in turn regulate cell survival and proliferation.[9,10] The phosphorylation of Akt (p-Akt) regulates expression of survivin via promoting hypoxia-inducible factor-1a expression. Hypoxia-inducible factor-1a binds to survivin promoter, and then promotes survivin transcription and translation; survivin is 1 member of inhibitor of apoptosis protein family to inhibit apoptosis in cancers.[11,12] Previous studies reported that p-Akt and survivin were significantly expressed in thyroid carcinoma,[13–15] whereas it remains unknown whether IGF-1R/p-Akt/survivin pathway is involved in the pathogenesis of PTC in diabetes or not. In this study, we compared the immunohistochemical expression and intensity of IGF-1R, p-Akt, and survivin in PTC patients with or without T2DM to investigate the mechanistic link between diabetes and PTC.
2 Materials and methods
2.1 Patients
Data on patients with PTC who were admitted to West China Hospital of Sichuan University from January 2009 to July 2014 were retrospectively searched. Inclusion criteria were as follows: PTC confirmed by histology or cytology, patients who had undergone thyroidectomy, patients older than 18 years, patients who have not undergone radiotherapy or chemotherapy before surgery, and patients with pre-existing T2DM before the diagnosis of PTC. Excluding criteria were as follows: coexistence of another type of thyroid malignancies, other recurrent or concurrent malignancies, a history of other neck surgery or radiation, a history of 131I treatment, type 1 diabetes mellitus, and diagnosis of diabetes mellitus or hyperglycemia after hospitalization.
To compare PTC patients with T2DM, we searched those PTC patients without the diagnosis of diabetes from the database whose age, gender, and the stage of tumor were not statistically different by χ2 test and rank-sum test compared with those of the T2DM group. All PTC patients without diabetes should be verified for the same inclusion and exclusion criteria mentioned earlier except for the diagnosis of T2DM, and the nondiabetic patients should have a morning fasting blood glucose <5.6 mmol/L.
2.2 Tissue samples
Tumor tissues were acquired from formalin-fixed pathological samples taken from the resected PTC specimens. Clinicopathological characteristics of patients with and without T2DM were collected. The study was approved by the Biomedical Ethics Committee of West China Hospital, Sichuan University, China.
2.3 Immunohistochemical staining
The tissue samples of PTC patients were cut into sections of 4 μm, which were mounted on silanized slides. All primary antibodies were purchased from R&D America, and belonged to polyclonal: IGF-1R (AF-305-NA) at 1:100, p-Akt (AF887) at 1:100, and survivin (AF886) at 1:100. Two-step immunohistochemistry detection reagents were PV9003 from ZSJQ-BIO (Beijing, China) and K5007 from Dako (Glostrup, Denmark).
2.4 Evaluation of immunohistochemical staining results
Expressions of all antigens were examined by 2 investigators who were blinded to clinical data of the patients. Each sample was examined in a high-power field at ×400 magnification. The evaluation of staining was referred to a previous report with some modifications, as follows: immunostaining was classified based on staining intensity and percentage of positive tumor cells. Staining intensity was determined as 0 (absent), 1 (weak), 2 (moderate), and 3 (strong).[8,16] To compare the positive degree of antigen expression between the 2 groups, expression levels of the antigens were semiquantified using an immunohistochemistry score (range, 0–300) calculated by multiplying staining intensity with the percentage of positive tumor cells. The immunoreactivity was classified as follows: 0, score ≤60; 1+, 60 < score ≤ 140; 2+, 140 < score ≤ 220; and 3+, 220 < score ≤ 300. Patients with an immunohistochemistry score of ≤140 were considered as having negative to weak immunoreactivity and those with a score of >140 as having moderate to strong immunoreactivity, which will be used for the subsequent multivariate analysis.
2.5 Statistical analysis
Statistical analysis was performed using SPSS 16.0 (SPSS Inc, Chicago, IL). Chi-square and Fisher tests were used for comparison between clinicopathological characteristics of the 2 groups. Rank-sum test was used to compare differences of antigen expression between the 2 groups. Spearman rank correlation and κ consistency test were used to compare staining intensity between antigens. A P value of <0.05 was considered statistically significant.
3 Results
3.1 Clinicopathological characteristics
This study included 20 PTC subjects with T2DM and 21 PTC individuals without T2DM. As shown in Table 1, the ratio of hypertension was higher in PTC patients with T2DM than that in PTC subjects without T2DM. There were no significant differences in age, gender, body mass index (BMI), tumor size, pTNM status, lymph node metastasis, and extrathyroid invasion in PTC subjects with and without T2DM (Table 1).
Table 1 Clinicopathological data for PTC patients with and without T2DM.
3.2 Expression differences of IGF-1R, p-Akt, and survivin in PTC patients with or without T2DM
IGF-1R staining in the PTC patients with T2DM was observed to be obviously stronger than that in the PTC patients without T2DM (mean rank 24.73 vs 17.45, P = 0.037). No statistically significant differences were found in the expression of p-Akt and survivin between PTC patients with or without T2DM, as shown in Table 2. The representative pictures of immunohistochemistry of these molecules are shown in Figs. 1 to 3.
Table 2 The expression differences of IGF-1R/p-Akt/survivin in PTC with and without T2DM.
Figure 1 The representative figures of expression of IGF-1R in PTC (×400). IGF-1R = insulin-like growth factor-1 receptor, PTC = papillary thyroid carcinoma.
Figure 2 The representative figures of expression of p-Akt in PTC (×400). p-Akt = phosphorylation of Akt, PTC = papillary thyroid carcinoma.
Figure 3 The representative figures of expression of survivin in PTC (×400). PTC = papillary thyroid carcinoma.
3.3 Expression correlation and consistency among IGF-1R/Akt/survivin proteins in PTC patients with T2DM
In 20 PTC patients with T2DM, p-Akt expression was consistent with survivin expression by κ analysis (k = 1.000, P < 0.001). IGF-1R expression was not consistent with p-Akt or survivin expression (IGF-1R and p-Akt: k = 0.318, P = 0.144; IGF-1R and survivin: k = 0.318, P = 0.144). Spearman rank analysis showed that the expression intensity of p-Akt was positively correlated with survivin (correlation coefficient 0.820, P < 0.001). However, IGF-1R expression was not correlated with p-Akt or survivin (all P > 0.05).
3.4 The correlation of clinicopathological factors with the expression of IGF-1R in PTC patients with T2DM
In order to investigate whether the immunoreactivity of IGF-1R was associated with TNM stages or tumor size, the immunoreactivity of IGF-1R was classified into IGF-1R negative to weak immunoreactivity group and IGF-1R moderate to strong immunoreactivity group according to immunohistochemistry score mentioned earlier. As shown in Table 3, the ratio of tumor size >10 mm was significantly higher in IGF-1R moderate to strong immunoreactivity group than in IGF-1R negative to weak immunoreactivity group (Fisher test, P = 0.007).
Table 3 The IGF-1R expression and clinicopathological differences in PTC with T2DM.
4 Discussion
In this study we compared IGF-1R expression in PTC patients with and without diabetes to investigate the potential mechanistic link between diabetes and PTC, and the data showed that in PTC tissues IGF-1R was significantly highly expressed in diabetics than in nondiabetics. A previous study reported that IGF-1R expression is significantly higher in non-small cell lung cancer patients with preexisting T2DM.[8] Significantly higher level of IGF-1R messenger ribonucleic acid is observed in colorectal cancer tissue in patients with T2DM when compared with that in subjects without T2DM.[17] The higher expression of IGF-1R involved in diabetes affecting carcinogenesis may be associated with hyperinsulinemia and hyperglycemia accompanied with diabetes. In T2DM patients, hyperinsulinemia reduces liver IGF-1-binding-protein synthesis, and increases serum level of free IGF-1 that integrates with IGF-1R and then activates downstream signaling pathway to facilitate cell proliferation and stimulate cancer cell growth.[18–20] In addition, hyperglycemia characterized with diabetes directly or indirectly promotes IGF-1R phosphorylation (activation) by stimulating advanced glycation end product production to facilitate tumor cell proliferation.[21,22] Our results indicated that IGF-1R may mediate the mechanism of PTC carcinogenesis in diabetes.
To further investigate the intracellular signaling pathway activated by IGF-1R in PTC patients with T2DM, we analyzed the expressions of p-Akt and survivin, the IGF-1R downstream molecules in PTC patients with and without diabetes. The immunohistochemical results showed that p-Akt and survivin expressions were not significantly different between PTC patients with and without diabetes. Although survivin expression was highly consistent and positively correlated with p-Akt expression, no significant consistency or correlation between IGF-1R and p-Akt or survivin expression was found in patients with diabetes. The results suggested that the p-Akt/survivin pathway may not be involved in diabetes affecting PTC. IGF-1R activation by tyrosine phosphorylation of β-subunit results in activation of PI3K/Akt and RAS/MAPK pathways that in turn regulate cell survival and proliferation, respectively.[9,10] Moreover, a previous study found that the activation of MAPK signaling by insulin/IGF-1 is responsible for the proliferation of colon cancer cells with T2DM.[23] Diabetes mellitus stimulates pancreatic cancer growth via the MAPK pathway.[24] High glucose increases glucose uptake and glycolytic activity, and stimulates cell proliferation through modulating the MAPK pathway.[25] Apart from PI3K/Akt pathway, MAPK pathway should be suspected to activate and greatly implicate in PTC development.[26] Even if there has been no research to investigate the MAPK pathway in PTC patients with T2DM, it is notable that MAPK pathway may be involved in diabetes affecting PTC. In PTC patients with diabetes, the percentage of tumor >10 mm was significantly higher in IGF-1R moderate to strong immunoreactivity group compared with that in IGF-1R negative to weak immunoreactivity group. The positive relationship between PTC size and IGF-1R expression in diabetes suggested that IGF-1R may promote tumor growth via activating cell proliferation pathway. However, this suggestion and the specific mechanisms and pathways activated by IGF-1R in PTC patients with T2DM need to be further demonstrated and investigated.
In addition, this study incidentally found that the percentage of BMI >24 kg/m2 was higher in PTC patients with diabetes than in PTC patients without diabetes. Similarly, the ratio of hypertension in diabetics was significantly higher than that in nondiabetics (55.00% vs 14.29%) in this study. The relationship between obesity, hypertension, insulin resistance, and hyperinsulinemia is consanguineous.[27–33] That the diabetics had higher ratio of BMI >24 kg/m2 or hypertension than nondiabetics was a limitation of this study; however, the most significant baseline characteristics, for example, number of cases, TNM stage, and tumor size, were consistent in patients with and without diabetes, and hence the results were persuasive and convinced.
5 Conclusions
In conclusion, this study found that in PTC patients with T2DM, IGF-1R was overexpressed when compared with that in subjects without T2DM, and IGF-1R immunoreactivity was associated with tumor size. It is suggested that IGF-1R may be involved in diabetes affecting tumorigenesis and tumor growth of PTC. However, further research is needed.
Abbreviations: BMI = body mass index, IGF-1R = insulin-like growth factor-1 receptor, MAPK = mitogen-activated protein kinase, p-Akt = phosphorylation of Akt, PI3K = phosphatidylinositol 3-kinase, PTC = papillary thyroid carcinoma, T2DM = type 2 diabetes mellitus.
YY and FH contributed equally to this work.
Authorship: YY and FH summarized data and wrote the manuscript; YY, WW, and RM collected data; HH conceived of the project concept, assisted with the data interpretation, and modified the manuscript.
The authors have no funding and conflicts of interest to disclose.
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PMC005xxxxxx/PMC5371470.txt |
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Medicine (Baltimore)Medicine (Baltimore)MEDIMedicine0025-79741536-5964Wolters Kluwer Health 28328833MD-D-16-0603310.1097/MD.0000000000006397063973400Research ArticleSystematic Review and Meta-AnalysisDrug-coated balloon in combination with bare metal stent strategy for de novo coronary artery disease A PRISMA-compliant meta-analysis of randomized clinical trialsLu Wenjie MDZhu Yongjian MDHan Zhanying PhDWang Xi MDWang Xule PhDQiu Chunguang MD∗Piraino. Davide Department of Cardiology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan, China.∗ Correspondence: Chunguang Qiu, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan, China (e-mail: qiu_contribution@163.com).3 2017 24 3 2017 96 12 e63972 10 2016 13 2 2017 24 2 2017 Copyright © 2017 the Author(s). Published by Wolters Kluwer Health, Inc.2017This is an open access article distributed under the terms of the Creative Commons Attribution-Non Commercial License 4.0 (CCBY-NC), where it is permissible to download, share, remix, transform, and buildup the work provided it is properly cited. The work cannot be used commercially without permission from the journal. http://creativecommons.org/licenses/by-nc/4.0Abstract
Background:
Studies examining the efficiency of drug-coated balloon (DCB) + bare metal stent (BMS) compared with stents alone for de novo lesions have reported inconsistent results. The present comprehensive meta-analysis of randomized controlled trials (RCTs) assessed and compared the clinical efficacy and safety of DCB + BMS with those of stents alone for de novo coronary artery disease.
Methods:
We formally searched electronic databases before September 2016 to identify potential studies. All RCTs were eligible for inclusion if they compared DCB + BMS with a control treatment (drug-eluting stent [DES] alone or BMS alone) in patients with de novo coronary artery disease.
Results:
Eleven RCTs with a total of 2196 patients met the inclusion criteria were included in our meta-analysis. Subgroup analysis indicated DCB plus BMS was associated with poorer outcomes when compared with DES alone in primary endpoint {(in-segment late lumen loss [LLL]: mean difference [MD], 0.19; 95% confidence interval [CI], 0.06–0.32; P = 0.0042) and (major adverse cardiovascular events [MACEs]: risk ratio [RR], 1.88; 95% CI, 1.44–2.45; P < 0.0001)}. However, DCB + BMS had nonsignificantly lower LLL than BMS alone (in-segment LLL: MD, −0.14; 95% CI, −0.33–0.04; P = 0.24), and was more advantageous in reducing MACE incidence, with borderline significance (MACEs: RR, 0.67; 95% CI, 0.45–0.99; P = 0.05).
Conclusions:
In summary, the present results do not favor the DCB + BMS strategy as an alternative therapeutic method to DES implantation for de novo coronary artery lesions in percutaneous coronary intervention (PCI). Additional well-designed large RCTs with long-follow-up periods are required to clarify the inconsistent results.
Keywords
bare metal stentde novo coronary artery diseasedrug-coated balloondrug-eluting stentOPEN-ACCESSTRUE
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1 Introduction
Recent evidences support using paclitaxel drug-coated balloon (DCB) catheters as a therapeutic method for de novo coronary lesions,[1,2] in-stent restenosis (ISR),[2,3] small coronary vessels,[4,5] and coronary bifurcation lesions.[6,7] DCB was designed to achieve comparable efficacy in neointimal proliferation through local drug delivery without requiring foreign body implantation or prolonged dual antiplatelet therapy (DAPT). The advantages of DCB include homogeneous and high concentration's drug delivery to the entire vessel wall, absence of stent layer, and absence of the polymer that could lead to chronic inflammation. DCB is a promising device to overcome some limitations of DES in percutaneous coronary intervention (PCI), such as ISR,[8] late and very late stent thrombosis,[9] and risk of bleeding caused by prolonged DAPT.[10] Although DCB has shown remarkable angiographic and clinical effects in coronary artery interventional therapy, it has some limitations in the treatment of de novo coronary lesions. Elastic recoil and flow-limiting dissections may be the main reasons for therapy failure.[11] As the lack of mechanical scaffolding provided by stent struts, the use of DCB may not be ideal for complex coronary lesions. Therefore, a strategy combining DCB and bare metal stent (BMS) is a potential solution to overcome these limitations. The more rapid endothelialization and shorter DAPT duration of BMS than DES should be beneficial in certain scenarios. However, studies examining the efficiency of DCB + BMS compared with stents alone for de novo lesions have yielded inconsistent results,[11,12] and whether this strategy provides additional benefits remains unclear. Hence, we conducted a comprehensive meta-analysis of randomized controlled trials (RCTs) to assess and compare the clinical efficacy and safety of DCB + BMS with those of stents alone for de novo coronary lesions.
2 Methods
2.1 Search strategy
We comprehensively searched related papers in electronic databases (PubMed, Web of Science, and the Cochrane Central Register of Controlled Trials) before September 2016 to identify potential RCTs. The keywords were “paclitaxel-coated balloon,” “paclitaxel-eluting balloon,” “drug-eluting balloon,” and “drug-coated balloon.” Moreover, we evaluated relevant publications, including review articles and editorials.
Ethical approval was not required due to that this is a systematic review and meta-analysis. All included studies were approved by the notified ethics committees and institutional review boards. And this study was performed in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement.
2.2 Study selection and data extraction
Studies met the following inclusion criteria were included in the meta-analysis: RCTs of de novo coronary artery lesions intervention, DCB + BMS as a treatment arm, and eligible angiographic and clinical outcome data obtained during follow-up. The exclusion criteria were incomplete data and cases number less than 50. No restrictions were applied regarding the language of publication. Data abstraction was performed independently by 2 investigators (Lu and Zhu), and discrepancies were resolved by consensus. The following features of each eligible study were extracted using a standardized form: study and patient characteristics, intervention procedures, and angiographic and clinical outcomes.
2.3 Quality assessment
The Cochrane Collaboration tool[13] was used to methodologically assess the risk of bias to evaluate the quality of included trials. The following methodological domains were considered: random sequence generation, allocation concealment, blinding, drop-out rates (incomplete outcome data), addressing incomplete outcome data, selective reporting, and other potential sources of bias. After assessment, the included study were labeled as “low risk (L),” “high risk (H),” or “unclear risk (U).”
2.4 Endpoints and statistical analysis
The primary endpoints were in-segment late lumen loss (LLL) and major adverse cardiac events (MACEs). The secondary endpoints were in-segment binary restenosis (BR), in-segment minimum lumen diameter (MLD), and target lesion revascularization (TLR), myocardial infarction (MI), and death. MACEs were defined as a composite of death, MI, and TLR. The most similar endpoint was used if data for mentioned endpoint were unavailable. We conducted the meta-analysis by using the Cochrane Program Review Manager (v.5.0; Oxford, England) and STATA software (version 12.0; StatCorp, College Station, TX). According to the inverse variance fixed-effect model, categorical variables were calculated as the pooled risk ratio (RR) and 95% confidence intervals (CIs). Continuous variables were presented as estimated mean difference (MD) with a 95% CI. The I2 index was used to assess heterogeneity among studies. If I2 > 50% (substantial and important heterogeneity), a random effect model was used for quantitative data synthesis, whereas a fixed model was adopted. Begger Funnel plots and Egger tests were used to assess publication bias, with P < 0.05 as the threshold for statistical significance.[14,15]
3 Results
3.1 Characteristics of included studies
We initially screened a total of 7668 potential studies through a number of searches. After eliminating duplicates, 505 articles were examined. Of these, 11 RCTs[11,12,16–24] with a total of 2196 patients met the inclusion criteria were included in our meta-analysis. Figure 1 presents a flowchart of the overall search strategy. Among these 11 studies, 7 were multicenter studies and 4 were single-center studies. Four studies were 3-arm trials comparing the subgroups DCB + BMS, BMS alone, and DES alone; therefore, these studies were considered as 2 separate trials. We finally selected 9 studies comparing DCB + BMS with DES alone and 6 comparing DCB + BMS with BMS alone. The clinical and angiographic primary endpoints were provided in all trials, with follow-up durations of 6 to 24 months. Furthermore, DCB + BMS was used in 714 patients, whereas control treatments, namely BMS alone and DES alone, were used in 190 and 715 patients, respectively. The key demographic and angiographic characteristics of included the studies are summarized in Tables 1 and 2, respectively.
Figure 1 Flow diagram for identification processes.
Table 1 General characteristics of studies included in this meta-analysis.
Table 2 Lesions and devices characteristics of included studies.
3.2 Primary endpoint
LLL: This was reported in 9 of the 11 studies within follow-up periods of 6 to 9 months. The random effect model was used to quantitative analysis. Nine studies were included in the DCB + BMS versus DES subgroup analysis, whereas 5 studies were included in the DCB + BMS versus BMS subgroup analysis. Compared with the DES alone subgroup, the DCB + BMS subgroup exhibited a significant increase in LLL (MD, 0.19; 95% CI, 0.06–0.32; P = 0.0042). However, the DCB + BMS subgroup showed nonsignificantly lower LLL than did the BMS alone subgroup (MD, −0.14; 95% CI, −0.33–0.04; P = 0.24; Fig. 2 A).
Figure 2 Effectiveness of “DCB + BMS strategy” versus “DES alone” or “BMS alone” for treating de novo lesions. (A) Primary angiographic endpoint: in-segment late lumen loss. (B) Primary clinical endpoint: major adverse cardiovascular events (MACEs).
MACEs: These were observed in 10 of the 11 studies within a follow-up period of 6 to 24 months. The fixed effect model was used. Subgroup analysis indicated that compared with DES alone, DCB + BMS significantly increased MACEs (RR, 1.88; 95% CI, 1.44–2.45; P < 0.0001). The subgroup analysis showed that the DCB + BMS strategy was advantageous over the BMS treatment in reducing MACEs incidence, with borderline significant (RR, 0.67; 95% CI, 0.45–0.99; P = 0.05; Fig. 2B).
3.3 Secondary endpoint
In-segment BR rate. Seven and 3 studies with follow-up periods of 6 to 9 months were included in the DCB + BMS versus DES alone and DCB + BMS versus BMS alone subgroup analyses, respectively. We adopted the random effect model for analysis. Subgroup analysis showed the DCB + BMS strategy was inferior to DES alone strategy in reducing BR incidence (RR, 2.15; 95% CI, 1.07–4.31, P = 0.03). The DCB + BMS versus BMS subgroup analysis showed that DCB + BMS was beneficial, but the difference between both strategies was nonsignificant (RR, 0.74; 95% CI, 0.34–1.60, P = 0.44, respectively; Fig. 3 A).
Figure 3 Effectiveness of “DCB + BMS strategy” versus “DES alone” or “BMS alone” for treating de novo lesions. Secondary angiographic endpoints: (A) in-segment binary restenosis rate; and (B) in-segment minimum lumen diameter.
In-segment MLD. Six and 3 studies with follow-up periods of 6 to 9 months were included in the DCB + BMS versus DES alone and DCB + BMS versus BMS alone subgroup analyses, respectively. Compared with DES alone, DCB + BMS had a significant lower MLD (MD, −0.25; 95% CI, −0.41 to −0.10; P = 0.001). A significant effect favoring DCB + BMS was detected in the DCB + BMS versus BMS alone subgroup analysis (MD, 0.18; 95% CI, 0.03–0.33; P = 0.02; Fig. 3B).
TLR, MI, and Death. All 3 endpoints were reported in 9 of the 11 studies within follow-up periods of 6 to 24 months. Because of the low degree of heterogeneity, we used the fixed effect model for the quantitative analysis. TLR: The analysis indicated a significantly higher risk of TLR in the DCB + BMS subgroup than in the DES alone subgroup (RR, 1.94; 95% CI, 1.27–2.98; P = 0.002), and the incidence rate of TLR did not differ significantly between the DCB + BMS subgroup and BMS alone subgroup (RR, 0.71; 95% CI, 0.47–1.09; P = 0.012; Fig. 4 A). MI: The analysis showed no significant difference in MI incidence between the DCB + BMS and DES alone subgroups (RR, 0.88; 95% CI, 0.32–2.42; P = 0.81). Similarly, the incidence rate of MI was comparable following DCB + BMS and BMS alone implantation (RR, 0.51; 95% CI, 0.16–1.67; P = 0.27; Fig. 4B). Death: The analysis revealed that death did not differ significantly in the DCB + BMS and DES subgroups (RR, 5.91; 95% CI, 0.72–48.39; P = 0.10); similar results were observed in the DCB + BMS versus BMS subgroup analysis (RR, 0.20; 95% CI, 0.02–1.70; P = 0.14).
Figure 4 Effectiveness of “DCB + BMS strategy” versus “DES alone” or “BMS alone” for treating de novo lesions. Secondary clinical endpoints: (A) target lesion revascularization, (B) MI, and (C) death.
3.4 Sensitivity analysis
According to the results of heterogeneity analysis, we conducted sensitivity analysis between the DCB + BMS and control groups (DCB + BMS vs DES and DCB + BMS vs BMS subgroups) at all observed endpoints. We sequentially eliminated one study at a time and observed that no study strongly influenced the overall results.
3.5 Publication bias
Egger test showed no evidence of significant publication bias in this meta-analysis (P > 0.05). In addition, the funnel plot was symmetrical, suggesting no publication bias (Fig. 5).
Figure 5 Funnel plot for publication bias. (A) Primary angiographic endpoint: in-segment late lumen loss. (B) Primary clinical endpoint: major adverse cardiovascular events (MACEs).
3.6 Risk of bias assessment
The assessment of the risk of bias is presented in Table 3. Seven and 5 of the included studies showed a low risk of bias in random sequence generation and allocation concealment, respectively. Five studies showed a low risk of bias in the blinding of participants, and 5 had a high risk of bias in the blinding of the outcome assessment. All studies have a low risk of bias regarding incomplete outcome data and selective outcome reporting.
Table 3 Assessment of risk of bias in the included studies using Cochrane criteria.
4 Discussion
Our present meta-analysis included the largest number of RCTs to date showed that although the DCB + BMS strategy performed more favorably than did the BMS alone strategy, it was not superior to DES alone strategy in the treatment of de novo coronary lesions.
DES implantation is the first choice of treatment in PCI. Its dramatic ability to inhibit neointimal hyperplasia through sustained elution of cytostatic drugs turns into a significantly reduced repeat revascularization rate in clinical trials.[25,26] Nevertheless, cases of treatment failure, mainly because of ISR and stent thrombosis (ST),[27,28] have attracted more attention considering the sizeable number of patients with DES implantation. Various factors are required to satisfactorily resolve, such as slow drug release, polymer-induced inflammation, endothelial dysfunction, and coronary vasoconstriction disturbance.[29,30] Therefore, paclitaxel DCB may be an emerging therapeutic alternative that has the advantages of operative simplicity and homogeneous antiproliferative agent release along the entire device.[20] To avoid the disadvantages of DES, researchers have tried to combine DCB and BMS to achieve benefits by DCB provided local release antiproliferative agents and BMS prevented acute postangioplasty recoil.
Determining an optimal treatment for de novo lesions remains challenging. Although BELLO[4] study showed that, compared with PES in small vessels (reference diameter 2.8 mm), DCB yielded significantly lower in-stent (in-balloon) late loss and similar rates of restenosis and revascularization. However, there have been few well-designed “head to head” studies comparing the DCB and DES strategies for lesions with lumen diameters of more than 2.5 mm. All studies included in the present meta-analysis had applied the DCB + BMS therapeutic strategy for de novo coronary lesions (lumen diameter >2.5 mm). Nevertheless, the pooled results of our research showed that the clinical efficacy and safety of the DCB + BMS strategy were not equivalent to those of the DES alone strategy for de novo coronary lesions. Regarding the MACEs rate, replacing DES implantation with DCB + BMS was not beneficial in simple de novo coronary lesion intervention.
This finding may be explained by various factors. First, the lack of sufficient uncoated balloon predilation in some included study[17,21] may have contributed to the result. Predilation before DCB use could improve drug uptake by the vessel wall because of the creation of microdissections, thus facilitating drug transport through the intima and media, particularly for calcified lesions.[18] The Valentines II[1] trial adopted regular balloon predilatation of the target lesion followed DIOR II DCB reported low in-segment LLL and TLR rates. Meanwhile, 1 RCT, which adopted regular balloon predilatation, compared the efficacy of BMS and DCB combination versus BMS alone in patients with non-ST elevation acute coronary syndrome also reported significantly lower LLL but the absence of a favorable effect on patient clinical outcomes.[31] Second, we speculated “geographical miss” caused by unfavorable geometric proportions as a potential influencing factor because the reference point for stent or balloon placement was missing. One clinical trial reported that patients treated with DCB predilatation with an additional BMS implantation had a very high proportion of geographical miss, which was identified as an independent significant predictor of restenosis.[32] If stent deployment precedes DCB dilatation, the contact surface between the balloon and vessel wall is reduced by approximately 15% owing to the surface of the stent struts.[33]
Another possible reason is intimal hyperplasia. The OCTOPUS trial, which used optical coherence tomography, reported that DCB + BMS was associated with more pronounced neointimal proliferation than DES.[23,34] The IVUS study used intravascular ultrasound also showed more pronounced neointimal hyperplasia in the DCB + BMS group, leading to more revascularization than that in the DES group.[35] The reason for this finding is not yet satisfactorily explained. Possible influencing factors are the interaction of the mounted stent with drug release from DCB, stent and balloon lengths, drug concentrations, and stent system.
Our meta-analysis included 2 strategies for DCB application: pre- and post-BMS implantation. Theoretically, DCB used before BMS implantation could increase the risk of geographical mismatch, because the stent may be implanted partly outside the DCB-treated segment. By contrast, DCB used after BMS implantation might affect the drug delivery to the vessel because of interposition of the stent struts.[24] An optical coherence tomography (OCT) study investigated the effects of the sequence of DCB and BMS (i.e., DCB first and BMS first) and stated that the BMS-first sequence translated into more favorable apposition than did the DCB-first sequence, as evidenced by the significantly low proportion of incomplete stent apposition (ISA) struts and nonsignificantly low ISA areas and volumes in the former.[36] However, the INDICOR trial[33] and another OCT study[36] used DCB from different manufacturers suggested that, the sequence of DCB application does not affect LLL, MACEs, and in-stent neointimal hyperplasia. Similar clinical and angiographic results were reported by the IN-PACT CORO trial.[24]
Finally, a possible explanation for these findings is that the currently used DCB, particularly first-generation DCBs, failed to warrant sufficient bioavailability of paclitaxel at the lesion site. Bondesson et al[37] reported the differential treatment outcomes of various DCBs, and this variation may be even larger than that caused by DES because drug delivery to the vessel wall is crucial during balloon inflation. Regarding LLL, the pharmacokinetics of paclitaxel with first-generation DCBs may have been insufficient to provide comparable benefits. A recent experimental study[38] showed much higher drug concentrations into the vessel wall by using the DIOR-II DCB than DIOR-I, combined with a shorter inflation time. Hence, using a second-generation DCB with a BMS, higher tissue drug delivery dose, might lead to better angiographic and clinical outcomes for de novo lesions.
The present meta-analysis has several potential limitations. First, the sample sizes were small in all except one of the studies.[19] Second, because the studies had a relatively short follow-up durations, definitive conclusions will necessitate clinical follow-up for several additional years. Finally, most included studies were conducted in Western countries, hence, data from non-Western countries were inadequate to precisely assess the clinical efficacy and safety of the DCB + BMS strategy for de novo lesions. Thus, further large, multicenter, well-designed randomized trials recruiting patients from more countries are required to provide additional insights.
5 Conclusion
The present meta-analysis does not favor the DCB + BMS strategy as an alternative therapeutic method to DES implantation for de novo coronary artery lesions in PCI. Additional well-designed large RCTs with long follow-up periods are required to resolve this concern.
Abbreviations: BMS = bare metal stent, BR = in-segment binary restenosis, CI = confidence interval, DAPT = dual antiplatelet therapy, DCB = drug-coated balloon, ISR = in-stent restenosis, LLL = in-segment late lumen loss, MACEs = major adverse cardiovascular events, MD = mean difference, MI = myocardial infarction, MLD = in-segment minimum lumen diameter, PCI = percutaneous coronary intervention, PEB = paclitaxel-eluting balloon, RCTs = randomized controlled trials, RR = risk ratio, TLR = target lesion revascularization.
WL and YZ contributed equally to this work.
The authors have no conflicts of interest to disclose.
==== Refs
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PMC005xxxxxx/PMC5371471.txt |
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Medicine (Baltimore)Medicine (Baltimore)MEDIMedicine0025-79741536-5964Wolters Kluwer Health 28328834MD-D-16-0622310.1097/MD.0000000000006399063994400Research ArticleObservational StudyVarying postresection lactate dehydrogenase with overall survival of early stage pancreatic cancer patients A retrospective studyXiao Yuanyuan PhDabXie Zhihui MScShao Zhenyi MScChen Wen MScXie Hua MPHcQin Guoyou PhDbd∗Zhao Naiqing MSbd∗Li. Yuqing a School of Public Health, Kunming Medical University, Kunming, Yunnanb Department of Biostatistics, School of Public Health, Fudan Universityc Information Center, Shanghai Municipal Commission of Health and Family Planningd Key Lab of Health Technology Assessment, Ministry of Health (Fudan University), Shanghai, China.∗ Correspondence: Guoyou Qin, Department of Biostatistics, School of Public Health, Fudan University, Shanghai, China (e-mail: gyqin@fudan.edu.cn); Naiqing Zhao, Department of Biostatistics, School of Public Health, Fudan University, Shanghai, China (e-mail: nqzhao1954@163.com).3 2017 24 3 2017 96 12 e639912 10 2016 9 2 2017 23 2 2017 Copyright © 2017 the Author(s). Published by Wolters Kluwer Health, Inc.2017This is an open access article distributed under the terms of the Creative Commons Attribution-Non Commercial-No Derivatives License 4.0 (CCBY-NC-ND), where it is permissible to download and share the work provided it is properly cited. The work cannot be changed in any way or used commercially without permission from the journal. http://creativecommons.org/licenses/by-nc-nd/4.0Abstract
Several previously published studies revealed a hazardous role of pretreatment lactate dehydrogenase (LDH) in survival of advanced or metastatic pancreatic cancer (PC) patients. Nevertheless, in early stage PC patients who are eligible for curative resection, the prognostic role of postresection LDH has never been discussed. In this study, we aimed to explore the prognostic significance of varying postresection LDH among early stage PC patients. In total, 80 PC patients who received curative resection were retrospectively selected from a population-based electronic inpatients database which originated from Shanghai, China. A dynamic survival analysis method, counting process approach in combination with the multiple failure-time Cox model, was applied to evaluate the association between postresection LDH and OS. The multiple failure-time Cox model found that age, resection modality, and postresection LDH were significantly associated with OS: an elevated LDH (defined as > 250 U/L) was related to 2.93 (95% CI: 1.26–6.79) folds of death hazard. Further analysis disclosed an identifiable dose–response association between LDH and OS: compared with LDH≤155 U/L, the HRs for 155 U/L < LDH < 196 U/L, and LDH≥196 U/L were 2.07 (95% CI: 0.88–4.88) and 3.15 (95% CI: 1.30–7.59), respectively. Our study results suggest that postresection LDH is a prominent prognostic factor in this group of early stage PC patients. Maintaining normally ranged LDH after resection might bring about survival benefit in early stage PC patients.
Keywords
early stage pancreatic cancerlactate dehydrogenaseoverall survivalOPEN-ACCESSTRUE
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1 Introduction
Pancreatic cancer (PC) remains one of the most lethal malignant tumors, for nearly 95% patients will die within 5 years after diagnosis.[1] The lack of specific symptoms in the early stage of disease mainly contributes to the dismal survival of PC. It has been estimated that, among all newly diagnosed patients, only 15% to 20% will be eligible for curative resection. More depressing is that, even in resected PC patients, the overall 5-year survival rate only ranges from 18% to 24%.[2,3] Thus, in early stage PC patients, other nontreatment factors of possible prognostic significance should be intensively searched and investigated.
Compared with normal cells, the most distinctive feature in metabolism of cancer cells is the enhanced glycolysis capacity even in the presence of sufficient oxygen. This phenomenon is well known as the Warburg effect. Recently, along with the uncovering of laboratory evidences which connect aerobic glycolysis to cancer initiation and proliferation,[4,5] lactate dehydrogenase (LDH), a central enzyme involved in the final step of the Warburg effect in converting pyruvate to lactate, is attracting growing study interest.
The prognostic value of serum LDH has been widely discussed in many types of cancer. For example, an elevated pretreatment serum LDH has been found associated with deteriorated survival of small-cell lung cancer, nasopharyngeal cancer, colon cancer, and aggressive lymphoid cancer.[6–11] In PC, although several studies also reported a significant inverse association between pretreatment LDH and survival in advanced or metastatic patients,[12–14] in early stage patients who are eligible for curative resection, the prognostic role of postresection LDH has never been discussed.
Similar to other blood indicators, within a given period, usually LDH constantly varies from one single test to another; in this case, when discussing the association between LDH and cancer survival, this variation should not be ignored. Nevertheless, nearly all currently available studies chose to analyze the prognostic role of LDH measured at certain transient moments by using the common Cox proportional hazards model; dynamic survival analysis methods were seldom seen.
In this study, we aimed to discuss the relationship between varying postresection LDH and the overall survival (OS) of early stage PC patients. To effectively adjust for LDH variation, we restructured the original survival data into counting process style and adopted multiple failure-time Cox model subsequently.
2 Methods
2.1 Patients
After Institutional Research Ethics Board of Fudan University approved, we retrospectively selected PC patients from a mega population-based electronic database. This database was established at the end of 2011 and has been accumulating on daily basis ever since. Relevant information of patients who were admitted in selected county-level and above hospitals within the Shanghai Metropolitan area, China, was mandatorily collected and reported. In this study, we chose early stage PC patients based on the following criteria: (1) histopathologically confirmed exocrine cancer of pancreas; (2) resection with curative intention was performed (patients who only received palliative resection were excluded); (3) the date of diagnosis was between January 1, 2012, and December 31, 2013; (4) had at least 1 serum LDH test result after resection; (5) other vital information for analysis, such as age, gender, date of operation, modality of resection, and adjuvant chemotherapy, was complete. In the end, 80 patients were eligible for inclusion.
2.2 Outcome
The outcome of interest was OS. The survival period was defined as time interval between the date of curative resection and the date of death, which was ascertained through external matching with death registration system on January 31, 2015.
2.3 Adjuvant chemotherapy
Adjuvant chemotherapy was defined as the administration of gemcitabine alone or in combination with the following agents after curative resection: nab-Paclitaxel, 5-fluorouracil, Irinotecan, and Oxaliplatin.
2.4 Counting process approach for time-varying covariates
Based on commonly used Cox proportional hazards model, a simple extension called “counting process approach” was initially forwarded by Anderson and Gill[15] to cope with recurrent event or time-varying covariates. The logic behind this method is simple: suppose a study subject has intermittent measurements of a time-varying covariate during the whole survival period, we can then split the original observation into a group of “subobservations” at the time points this covariate varied. Therefore, in the transformed database, for every subobservation, this covariate will be treated as constant, and multiple failure-time Cox model, which extra adjusts for inter-correlations among subobservations stemmed from the same subject, by using “sandwich” estimator for instance,[16] can be applied.
2.5 Statistical analysis
At first, we transformed the original survival data into counting process style based on LDH fluctuations, then, we applied multiple failure-time Cox model to evaluate the association between postresection LDH and OS. A LDH level no higher than 250 units/liter (U/L) is widely used to define normally raged LDH as suggested by some previous publications. [12,13,17] Thus, in the current study, LDH was categorized as either “normal” or “elevated” by using the cut-off of 250 U/L. The influence of other available potential confounders, such as age, gender, resection modality, adjuvant chemotherapy, was simultaneously controlled for. In order to simplify the problem, we assumed that the effect of LDH and the baseline hazard were constant during the whole survival period. We used the univariate method to screen candidate covariates, and variables with P values less than 0.10 were included in the multivariate model.
We further divided LDH into subgroups by using percentiles to explore dose–response association between LDH and OS. All statistical analyses were executed by SAS (version 9.2, SAS Institute Inc., Cary, NC), and the significance level was defined as 2-tailed probability less than 0.05.
3 Results
3.1 Characteristics of patients
The general characteristics of 80 early stage PC patients were briefly summarized in Table 1. The mean age at diagnosis for all patients was 60.93 years. Males and females were almost equivalent in count. Nearly a half of patients (48.75%) received gemcitabine-based adjuvant chemotherapy after curative resection. As to resection modality, 46 (57.50%) patients went through Whipple pancreaticoduodenectomy. In total, 45 patients had experienced death before January 31, 2015, accounted for 56.25%. The shortest and longest survival lengths were 53 days and 744 days, respectively, and the median of survival length was 489 days. Monthly means of LDH were calculated to show the longitudinal variation of postresection LDH in Fig. 1: along with the extension of survival length, monthly means of LDH randomly fluctuated, no prominent pattern was discerned.
Table 1 Characteristics of 80 resected PC patients.
Figure 1 Postresection LDH fluctuation among PC patients. LDH = lactate dehydrogenase, PC = pancreatic cancer.
3.2 Multiple failure-time Cox model fitting results
After transforming the original survival data into “counting process” style, totally we obtained 455 subobservations from 80 patients. Based on univariate results, other than the LDH level, 2 covariates from the original 4 available potential confounders were included into a multivariate model: age at diagnosis and resection modality. Interactions between age and LDH, resection modality, and LDH were all insignificant (χ2 = 0.55, P = 0.46; χ2 = 1.29, P = 0.26). After adjusting for inter-correlations by using the sandwich estimator, we found that age, resection modality, and LDH level were all prominently associated with OS in resected PC patients: every 5-year increase in age corresponded to 32% extra hazard of death; PC patients who received Whipple resection exhibited 2.07 (95% CI: 1.00, 4.27) times of death hazard; compared with patients of normally ranged LDH, the HR for patients with an elevated postresection LDH was 2.93 (95% CI: 1.26–6.79) (Table 2).
Table 2 Multiple failure-time Cox model fitting results.
3.3 Dose–response association between LDH and OS
LDH test results were divided into 3 subgroups by using the 33rd (155 U/L) and the 66th (196 U/L) percentiles. After adjusting for age and resection modality, the multiple failure-time Cox model disclosed a discernible dose–response association: along with the increase of LDH value, the hazard of death was also increasing: compared with LDH≤155 U/L, the HRs for 155 U/L < LDH < 196 U/L and LDH≥196 U/L were 2.07 (95% CI: 0.88–4.88) and 3.15 (95% CI: 1.30–7.59), respectively (Fig. 2).
Figure 2 Dose–response association between LDH and OS of PC. LDH = lactate dehydrogenase, OS = overall survival, PC = pancreatic cancer.
4 Discussion
In this retrospective study, through the application of dynamic survival analysis method, we evaluated the influence of varying LDH measured after curative resection on OS in 80 early stage PC patients. Based on analytical results, we found that an elevated LDH was in general significantly associated with compromised OS of PC.
In their newly published study, Wan et al[18] reported that high pretreatment serum LDH level was correlated with a shortened disease-free survival in nasopharyngeal carcinoma. Although currently, similar evidences in other malignant tumors are absent, we can still suspect that in resected PC patients, the overconcentration of serum LDH may also result in expedited relapse of the cancer. Besides, it has been suggested that there exists a positive feedback loop between hypoxia inducible factors (HIFs) and LDH in hypoxia microenvironment[19]; thus, in relapsed PC patients, an elevated serum LDH will stimulate the production of HIFs, and the overexpression of HIFs is closely associated with metastasis of solid tumors.[20] Moreover, LDH has been found directly promoted the growth of PC cells in vitro.[21] All these enumerated evidences may collectively contribute to the deteriorated OS in PC patients with elevated postresection LDH.
The major novelty of our study is the application of dynamic survival analysis method in estimating the association between varying postresection LDH and OS of PC. Although counting process adjustment in tandem with multiple failure-time Cox model is not novel in dealing with time-dependent covariates, their application in cancer survival literatures was seldom seen.
Nevertheless, our study does have several limitations. At first, we lack the data of some clinical characteristics of PC, such as tumor stage, size, location, and lymph node implication. It is highly likely that these unadjusted factors can bring confounding to our study results. Second, selection bias cannot be precluded, as we only analyzed PC patients whose vital information was complete. Besides, the sample size of patients was comparatively small, which impeded more thorough analysis of data, and to some extent, it may influence the accuracy of estimation. Finally, compared with OS, the association between postresection LDH and disease-free survival of PC undoubtedly bears a much more prominent clinical significance. However, because of data limitation, we can only expect to discuss this issue in future studies.
Despite aforementioned limitations, our study is the very first to analyze the prognostic significance of varying postresection LDH in early stage PC patients, and the credibility of results can be substantially consolidated by properly applied dynamic survival analysis method. Through the application of multiple failure-time Cox model, we successfully identified a prominent inverse association between LDH and OS. Our findings probably suggest that, for early stage PC patients, maintaining normally ranged LDH after resection may result in survival benefit. In 2 previously published studies, Le et al[22] and Xie et al[23] revealed that the inhibition of LDH activity showed a notable antiproliferation effect in animal xenograft models of human lymphoma, lung cancer, and PC. More importantly, various effective LDH inhibitors with minimum side-effects are already available now.[24–26]
To conclude, in the current study, we found that postresection LDH was significantly associated with OS in a group of early stage PC patients. Our study results hint a promising prospect of LDH maintenance in survival of early stage PC patients.
Abbreviations: HR = hazard ratio, LDH = lactate dehydrogenase, OS = overall survival, PC = pancreatic cancer.
YX and ZX contributed equally to this study.
Availability of data and materials: The datasets analyzed during the current study are not publicly available due to confidentiality agreement with the cooperative institutions, but are available by direct contact with the corresponding author under reasonable request.
Funding: This study was supported by National Natural Science Foundation of China (No. 81273187), National Science and Technology Major Project of the People's Republic of China (2012ZX09303–013–014).
The authors have no conflicts of interest to disclose.
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Medicine (Baltimore)Medicine (Baltimore)MEDIMedicine0025-79741536-5964Wolters Kluwer Health 28328837MD-D-16-0176810.1097/MD.0000000000006403064034800Research ArticleClinical Case ReportAtypical presentation of paroxysmal nocturnal hemoglobinuria treated by eculizumab A case reportQuinquenel Anne MDaMaestraggi Quentin MDbLecoq-Lafon Carinne MD, PhDcRégis Peffault de Latour MD, PhDdDelmer Alain MDaServettaz Amélie MD, PhDb∗Zhang. Yao-Jun a Department of Clinical Hematologyb Department of Internal Medicine, Infectious diseases and Clinical Immunologyc Hematology Laboratory, Robert-Debré Hospital, University of Reims Champagne-ardenne, Reimsd Hematology and Cellular therapy Unit, Saint Louis Hospital, AP-HP, Diderot Paris 7 University, Paris, France.∗ Correspondence: Amélie Servettaz, Department of Internal Medicine, Infectious Diseases and Clinical Immunology, Robert-Debré Hospital, rue du general Koenig, 51092 Reims, France (e-mail: aservettaz@chu-reims.fr).3 2017 24 3 2017 96 12 e640314 3 2016 4 1 2017 24 2 2017 Copyright © 2017 the Author(s). Published by Wolters Kluwer Health, Inc.2017This is an open access article distributed under the terms of the Creative Commons Attribution-Non Commercial-No Derivatives License 4.0 (CCBY-NC-ND), where it is permissible to download and share the work provided it is properly cited. The work cannot be changed in any way or used commercially without permission from the journal. http://creativecommons.org/licenses/by-nc-nd/4.0Abstract
Rationale:
Paroxysmal nocturnal hemoglobinuria (PNH) is a nonmalignant acquired hematopoietic stem cell disease, which can be revealed by hemolytic anemia, thromboembolism, or bonemarrow failure. Thrombosis can occur at any site, but coronary thrombosis is extremely rare. Controlled trials have demonstrated that eculizimab, an inhibitor of the terminal complement cascade, was able to reduce both hemolysis and thrombosis, but its efficacy in cases of PNH with coronary thrombosis is unknown.
Patient concerns and diagnoses:
We report herein the unusual case of a 73-year-old patient presenting with recurrent coronary syndromes without associated stenosis, fever, marked inflammatory syndrome, and anemia, leading to a delayed diagnosis of PNH.
Intervention and outcomes:
Eculizumab allowed the resolution of fever and inflammation, and prevented further thromboembolism.
Lessons:
This case emphasizes the importance of performing aflow cytometry test for PNH in front of unusual or unexplained recurrent thromboses. Thromboses, as observed in our case, may be associated with fever and marked inflammation. This case also provides useful information on eculizumab ability to prevent further thromboembolism in PNH patients with a medical history of arterial thrombosis.
Keywords
coronary thrombosiseculizumabPNHOPEN-ACCESSTRUE
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1 Introduction
Paroxysmal nocturnal hemoglobinuria (PNH) is a rare nonmalignant acquired clonal hematopoietic stem cell disorder that manifests with hemolytic anemia, bone marrow (BM) failure, and thrombosis. In nearly all the cases of PNH, an acquired somatic mutation of the X-linked PIG-A (phosphatidylinositol glycan class A) gene can be found, which is responsible for the expansion of hematopoietic stem cells lacking functional glycosylphosphatidylinositol (GPI) anchor. This results in the deficiency of complement inhibitory proteins, leading to complement-mediated hemolysis, and also activation of monocytes, granulocytes, and platelets with formation of prothrombotic microparticles. Moreover, hemolysis with liberation of high levels of free hemoglobin leads to scavenging of nitric oxide, which contributes to platelet activation and aggregation.[1,2]
In PNH, thrombosis can occur at any sites, the most common of which being hepatic vein (Budd–Chiari syndrome), mesenteric and portal veins, cerebral veins, and dermal veins. The reasons underlying the occurrence of thrombosis in these particular locations remain largely unknown.[3–5] Arterial thrombosis is far less frequent and such less common presentation may delay the diagnosis. Thromboembolism is the most common cause of mortality in PNH, and the 4-year survival of patients presenting with thrombosis at diagnosis was only 40% before the era of eculizumab.[6] Eculizumab is a humanized monoclonal antibody that blocks terminal complement pathway by binding to C5. This drug has dramatically changed the natural history of PNH.[7–12] Current evidence indicates that compared with placebo, eculizumab increases transfusion independency and health-related quality of life. Open-label studies and case reports suggest that eculizumab also reduces the risk of further thrombotic events.[7,12]
We report herein the case of a patient presenting with recurrent febrile arterial coronary thromboses, despite both antiplatelet treatment and curative anticoagulation. Fever and marked inflammatory syndrome delayed both diagnosis and initiation of eculizimab, and this delay was life-threatening for the patient. Finally, he was successfully treated with eculizumab and did no longer experience thrombotic events during the period of follow-up.
2 Case report
A 73-year-old male patient with a medical history of multiple thromboses (2 episodes of deep vein thrombosis in 1995 and 2011, and 2 episodes of pulmonary embolism in 1995 and 2004) presented in 2013 two consecutive acute coronary syndromes within a 1-month interval, while on continuous anticoagulation with vitamin K antagonists (fluindione). The patient was first admitted to cardiology department for acute thoracic pain in May 2013. Electrocardiogram evidenced inferior Q waves with ST elevation. Echography revealed antero-inferior akinesia. Serum troponins were not quantified because the patient was immediately transferred for coronarography. This coronary catheterization revealed an intraluminal thrombus in the right coronary artery. Balloon angioplasty was performed, but no stent was inserted because of unexplained fever. Antiplatelet therapy with both acetylsalicylic acid and clopidogrel was added to fluidione. A month later, the patient presented again with typical acute chest pain. Electrocardiogram always evidenced inferior Q waves with no other abnormalities. Echography found the known antero-inferior akinesia. Ultrasensitive troponins were elevated (560 ng/L, n < 14). A new coronary catheterization was performed and again evidenced a thrombosis in the right coronary artery and a new asymptomatic incomplete intraluminal obstruction of the circumflex artery (see Fig. 1, which illustrates the 2 successive coronary catheterizations). Again, angioplasty was performed without any vascular stenting because of unexplained fever since 2 months. Because of this persistent fever and marked inflammatory syndrome, additional investigations were performed. Clinically, the patient also presented with fatigue and signs of anemia. Hemoglobin level was 90 g/L, reticulocytes were 52 × 109/L, white blood cells 6.6 × 109/L with normal differential, and platelet count was 52 × 109/L. C-reactive protein (CRP) level was 147 mg/L. All tests for infectious, systemic inflammatory diseases, and vasculitis remained negative. Serum haptoglobin was decreased (<0.10 g/L) and lactate dehydrogenase (LDH) level was markedly elevated. Direct antiglobulin test was negative. A computerized tomography (CT) scan was performed and showed a thrombosis of the hepatic vein. Given the association of multiple thromboses, despite anticoagulation and signs of hemolysis, a flow cytometry test was performed and disclosed a big-sized PNH clone with 80% of neutrophils lacking expression of CD66b, CD16, and CD24 antigens, and more than 80% of monocytes lacking CD24 antigen. BM smears were normocellular and there were only mild signs of dysmegacaryocytopoiesis without excess blasts (2%). Karyotype was normal. The diagnosis of classical PNH was retained. Because of the presence of fever and inflammatory syndrome, and given the increased risk of severe infections after terminal complement blockade, the decision to start eculizumab was postponed. Rapidly, the patient presented with acute abdomen, hypotension, and functional renal insufficiency. He was admitted to the intensive care unit. A CT scan was not helpful in making a diagnosis, and a surgical exploration of the abdomen was performed. As no major abnormality was found, acute abdomen was hypothesized to be linked to multiple thromboses of small abdominal vessels, and treatment with eculizumab was finally started. Required prophylaxis, including vaccination against meningococcal and pneumococcal infection and penicillin V therapy, was performed. In addition, both anticoagulation and antiplatelet treatments were maintained. Shortly after the initiation of eculizumab, the patient recovered. Fever, abdominal pain, and inflammatory syndrome resolved. The main biological data observed during eculizumab therapy are reported in Table 1. During the entire follow-up period, the patient did not experience any further episode of thrombosis. LDH level returned to normal, but the patient still required repeated transfusions of red blood cell packs.
Figure 1 Coronary catheterization images. A, The patient was admitted in cardiology department for acute thoracic pain in May 2013. Electrocardiogram evidenced inferior Q waves with ST elevation. Echography revealed antero-inferior akinesia. Coronary catheterization showed a thrombosis in the right coronary artery (arrow). B, A month later, the patient presented again with typical acute chest pain despite dual antiplatelet therapy and vitamin K antagonist. Electrocardiogram always evidenced inferior Q waves with no other abnormalities. Echography found the known antero-inferior akinesia. Ultrasensitive troponins were elevated (560 ng/L, n < 14). A new coronary catheterization was performed and evidenced a thrombosis in the right coronary artery and a new asymptomatic incomplete intraluminal obstruction of the circumflex artery (arrow).
Table 1 Evolution of biological tests on eculizumab therapy.
Eight months later, in March 2014, a severe thrombocytopenia occurred. There were no signs of hemolysis. A new BM examination showed a normocellular BM with dysplasia of the 3 myeloid lineages and 11% blasts. This led to the diagnosis of refractory anemia with excess blast-2 (myelodysplastic syndrome with an excess of blasts in the BM comprised within the range of 11%–19%) associated with PNH.BM karyotype was still normal. Vitamin K antagonists were stopped because of thrombocytopenia, but antiplatelet treatment was maintained. Both platelet and red blood cell transfusions were performed, only leading to very transient improvement. Because of his age and poor physical condition, the patient was not eligible for BM transplantation. Hypomethylating treatment with 5-azacytidine (AZA) was added to eculizumab. After 2 cycles of AZA, the cytopenias remained unchanged. The patient was admitted in July 2014 to the intensive care unit because of septic shock due to the infection of his implantable chamber by Aeromonas veronii, rapidly leading to multiorgan failure and death, despite broad-spectrum antibiotics and vasopressor medication.
2.1 Patient consent
Patient's wife and children have given their informed consent for the case report to be published.
3 Discussion
This case reports an unusual presentation of PNH, as PNH was revealed by 2 acute coronary syndromes and elevated makers of inflammation mimicking vasculitis, infectious or connective tissue diseases, and delaying both diagnosis and treatment.
One of the particularities of this case is the presence of fever and marked inflammatory syndrome at diagnosis of PNH. Inflammation is not a classical feature of PNH, but may be observed in case of extensive thrombosis independently of the underlying etiology. It can also be driven by activation of the complement pathway as observed in PNH. Because of both inflammation and the increased risk of severe infections related to terminal complement blockade, diagnosis and treatment were delayed. During this time, the state of the patient worsened, leading to his transfer to an intensive care unit and to useless abdominal surgery. Recovery of the patient along with regression of both fever and inflammatory biological signs on eculizumab confirmed that extensive thromboses and complement activation were probably responsible for this critical state. Consequently, marked inflammation does not exclude the diagnosis of PNH and does not have to delay treatment with eculizumab if acute infection is not evidenced.
Thrombosis appears as a common complication of PNH, occurring in 40% of the patients during the course of the disease. The pathogenesis of such event is still unclear, and seems to involve both platelet and endothelial activation due to hemolysis, nitric oxide deficiency, and activation of the complement pathway. Arterial thromboembolism is far less frequent than venous thromboembolism in the setting of PNH (15% of the thromboses), and less than 20 cases of coronary thrombosis associated with PNH have been reported until now.[5,13–16] In a meta-analysis on 363 PNH cases with thrombosis, 12 episodes of myocardial infarction were described. Despite a very low frequency, thromboses of the coronary arteries were found to be a significant predictor of thrombosis-related mortality (Risk Ratio 20.53, 95% confidence interval [CI] 4.42–95.28).[5] This emphasizes the importance of performing rapidly flow cytometry analysis for PNH in patients with unexpected or recurrent thromboses even in arterial vessels.
As observed in this case and in previous reports, recurrent thromboses may occur despite curative anticoagulation and antiplatelet therapy in PNH.[10,17,18] In our patient, eculizumab was effective to prevent further venous or arterial thrombotic events. Eculizumab treatment has demonstrated its efficacy in reducing hemolysis and the need for red cell transfusions in a controlled trial.[8] It has been shown to also reduce the risk of further thrombosis in open-label studies[10] and in case reports, but not in a controlled trial.[19] Eculizumab blocks terminal complement pathway, which appears to be 1 of the key factors of thrombosis in PNH. Consequently, eculizumab is recommended in PNH patients not only in the presence of symptomatic hemolysis but also in cases with thrombosis, even if there are no prospective data concerning this complication.[3,12] In addition, an important question to be addressed is whether anticoagulation can be discontinued after either venous or arterial thromboses in the context of PNH treated with eculizumab. Successful discontinuation of anticoagulation in patients with previous thrombosis receiving eculizumab has been reported.[20] Nevertheless, continued anticoagulation is still recommended for PNH patients with a prior thrombosis receiving eculizumab, unless there are clear contra-indications to anticoagulation.[3] In our case, both vitamin K antagonists and antiplatelet treatment were initially maintained, but anticoagulation was stopped when the patient developed a myelodysplastic syndrome with severe thrombocytopenia. However, antiplatelet treatment was pursued, and no major hemorrhagic event occurred.
A variable degree of BM failure is present in all patients with PNH. In some patients, evidence of BM dysfunction might be subtle (inappropriately low reticulocyte count), whereas some other will present with marked cytopenias at diagnosis. In our patient, BM cellularity was initially normal, morphology was near normal, and there were no cytogenetic abnormalities. The PNH clone was over 50% by flow cytometry. The diagnosis of classical PNH was retained and there was no argument for “PNH in the setting of another specified BM disorder (eg, PNH/aplastic anemia or PNH/refractory anemia-MDS)”, as defined by the classification developed by the International PNH Interest Group.[2] Clonal evolution such as the development of a myelodysplastic syndrome or an acute myeloid leukemia is classical in PNH. In our case, the short delay between PNH diagnosis and the onset of myelodysplastic syndrome raises the question of a putative role of complement blockade in the arising of clonal evolution. In a recent retrospective treatment versus no treatment study, no significant difference regarding clonal evolution between patients receiving or not receiving eculizumab was found, even if a longer follow-up is needed.[12]
4 Conclusions
This case reports an uncommon presentation of PNH, with recurrent coronary syndrome and systemic inflammation. It emphasizes the importance of looking for hemolysis markers and performing rapidly a flow cytometry test for PNH in front of an unusual or unexplained thrombosis, even more if it occurs while on anticoagulation or antiplatelet treatment. This observation also provides information on the efficacy of eculizumab to prevent recurrences after arterial thrombosis.
Acknowledgment
The authors are grateful to Ms Wuibout for her corrections of the manuscript.
Abbreviations: AZA = 5-azacytidine, BM = bone marrow, CRP = C-reactive protein, CT = computerized tomography, GPI = glycosylphosphatidylinositol, LDH = lactate dehydrogenase, PIG-A = phosphatidylinositol glycan class A, PNH = paroxysmal nocturnal hemoglobinuria.
Conflicts of interest: Professor Peffault de Latour received research grant from Alexion and declared consultancy and international board membership for Alexion. The other authors stated they have no relevant conflicts of interest.
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Medicine (Baltimore)Medicine (Baltimore)MEDIMedicine0025-79741536-5964Wolters Kluwer Health 28328841MD-D-17-0030410.1097/MD.0000000000006409064097400Research ArticleObservational StudyIncreased HPV L1 gene methylation and multiple infection status lead to the difference of cervical epithelial cell lesion in different ethnic women of Xinjiang, China Yang-chun Feng MMedabYuan Zhang MMedcCheng-ming Liu MBBSbYan-chun Huang MBBSb∗Xiu-min Ma PhDa∗Schildgen. Oliver a Clinical Laboratory Center, The First Affiliated Hospital of Xinjiang Medical Universityb Clinical Laboratory Centerc Institute of Cancer Research, Tumor Hospital Affiliated to Xinjiang Medical University, Urumqi, People's Republic of China.∗ Correspondence: Huang Yan-chun, Clinical Laboratory Center, Tumor Hospital Affiliated to Xinjiang Medical University, No 789 Suzhou Road, Urumqi 830011, People's Republic of China (e-mail: xjhyc668899@sina.com); Ma Xiu-min, Clinical Laboratory Center, The First Affiliated Hospital of Xinjiang Medical University, No 137 Liyushan Road, Urumqi 830054, People's Republic of China (e-mail: mxm20160722@sina.com).3 2017 24 3 2017 96 12 e640916 1 2017 24 2 2017 27 2 2017 Copyright © 2017 the Author(s). Published by Wolters Kluwer Health, Inc.2017This is an open access article distributed under the terms of the Creative Commons Attribution-Non Commercial License 4.0 (CCBY-NC), where it is permissible to download, share, remix, transform, and buildup the work provided it is properly cited. The work cannot be used commercially without permission from the journal. http://creativecommons.org/licenses/by-nc/4.0Abstract
Human papillomavirus (HPV) L1 gene methylation deeply involved in the progression and heterogeneity of cervical cell epithelial lesions. The DNA ploidy also represented the early lesions of cervical cell, and it was associated with different HPV infection status in different ethnic women. So, the research was to explore whether it was possible that HPV L1 gene methylation and HPV infection status as the risk factors to lead to the differences of cervical epithelial cells’ lesions in different ethnics women.
The flow-through hybridization and gene chip for HPV genotypes test, general characteristics, and cervical exfoliated cell samples were collected from 94 Uygur and 79 Han women with HPV-16 infection. The cases were divided into the single HPV-16 (sHPV-16) infection group and multiple HPV-16 (mHPV-16) infection group in each ethnic women. The DNA ploidy was analyzed by flow cytometry, and the methylation-sensitive high resolution melting (MS-HRM) was used to test the HPV-16 L1 gene methylation, the results of methylation was segmented into mild methylation, moderate methylation, and severe methylation groups. Multifactor logistic analysis explored the relation between DNA heteroploid and HPV-16 infection status, HPV-16 L1 gene methylation in different ethnic women.
The higher proportion of mHPV-16 infection in Uygur than Han women (61.7% vs 38.0%). L1 gene methylation had statistic difference between single and mHPV-16 infection under the same ethnic women. The proportion of DNA heteroploid had statistic difference between different HPV-16 infection status or different L1 gene methylation grades in Han or Uygur women. Both L1 gene methylation and HPV infection status were the risk factors of DNA heteroploid. Compared to the sHPV-16 infection, the odds ratio (OR) of mHPV-16 infection were 4.409 (CI: 1.398–13.910) and 3.279 (CI: 1.069–10.060) in Han and Uygur women. Compared the mild L1 gene methylation, the OR of moderate L1 gene methylation were 3.313 (CI: 1.002–10.952) and 5.075 (CI: 1.385–18.603) in Han and Uygur women, the OR of severe L1 gene methylation were 20.592 (CI: 3.691–114.880) and 63.634 (CI: 10.400–389.368) in Han and Uygur women.
The study first reported that HPV L1 gene methylation and HPV infection status were the risk factors to the DNA heteroploid of cervical cell in different ethnics women, HPV L1 gene methylation and infection status should be recommended to the existing system of cervical lesion screening in order to provide better serves for the HPV infected women, especially for the ethnic women with high proportion of severe L1 gene methylation and multiple infection status.
Keywords
cervical epithelial cellDNA ploidyhuman papillomavirusL1 genemethylationOPEN-ACCESSTRUE
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1 Introduction
Cervical cancer occurs was in the womb malignant tumors of the vagina and cervix tube. In the developing countries, cervical cancer has the highest incidence in gynecological tumors.[1] It was the 8th high incidence cancer for women in the People's Republic of China, the general trend is higher incidence in rural than urban area, and the prevalence shows younger trend.[2] Xinjiang region had the highest incidence of cervical cancer in China, the incidences of cervical cancer were different in 2 major ethnic of Xinjiang, including Han and Uygur ethnic.[3]
Human papillomavirus (HPV) infection especially high-risk type HPV infection was a major cause of cervical lesions. There were numerous studies of HPV about cervical lesions, which focused on the relationship between cervical lesions and HPV-related gene and protein, such as L1 protein, L2 protein, E6, and E7 gene.[4–7] The L1 protein as the main capsid protein of HPV played an important role to recognize the host cell and keep persistent infection, which was a good index to evaluate the infection state in host cell.[8] Previous studies showed that the quantity of L1 protein was declining with aggravate of cervical cell lesion, L1 gene was the coding gene of L1 protein, its methylation was the major reason of L1 protein decreasing, which showed positive correlation to the degree of cervical lesions.[9,10] So, L1 gene methylation deeply involved in the progression and heterogeneity of cervical lesions, which was the potential clinical molecular target of cervical lesions to early diagnose and monitor the prognosis.[11]
DNA ploidy of cervical epithelial cells was contributed to monitor the lesion of HPV infected cervical cells and the prognosis of treatment.[12–14] Our previous studies had proved that single and multiple HPV infection status could influenced on the DNA ploidy of cervical exfoliated cells in Xinjiang women.[15] Meanwhile, we also found that, when the proportion of DNA heteroploid had no difference between Uygur and Han women in Xinjiang when they were in the same HPV infection status, but DI and S-phase cells’ peak percentage (SPF) as quantitative index of DNA ploidy had differences,[16] which was contradictory. We speculated that the persistent/transient infection and single/multiple infection primary lead to the contradictory. Because L1 gene methylation reflected the persistent or transient infection of HPV infection in the host cell, so it was speculated that, the L1 gene methylation and single/multiple infection should explain the contradictory.
In conclusion, the research was to explore whether it was possible that HPV L1 gene methylation and HPV infection status as the risk factors to lead to the differences of cervical epithelial cell lesions in different ethnics women.
2 Methods
2.1 Patients
The sample cases sourced from Xinjiang Uygur and Han women, who initially visited the gynecology department of the Tumor Hospital Affiliated to Xinjiang Medical University from July 2015 to October 2016. The chosen women must not accept any HPV-related treatment and HPV vaccine. A total of 173 HPV-16 genotype infected cases were collected, including 94 Uygur women and 79 Han women. At the same time, their general case characteristics were also collected. The ethics committee of the tumor hospital affiliated to Xinjiang Medical University approved the study and the consent procedure. The samples of flow cytometry DNA ploidy analysis, HPV genotype test, and HPV-16 L1 gene methylation were cervical exfoliated cells, which were collected as required by clinicians. The insufficient or polluted samples were ruled out. The research related to human had been complied with all the relevant national regulations, institutional policies, and in accordance with the tenets of the Helsinki Declaration, and had been approved by The Tumor Hospital Affiliated to Xinjiang Medical University institutional review board.
2.2 Reagents and instruments
The HPV genotype test used the 21 HPV GenoArray Diagnostic Kit from ChaoZhou Hybribio Biological Chemical Co. Ltd. (People's Republic of China). The method of HPV genotype test was flow-through hybridization and gene chip, the equipments for the test such as Thermal Cycler and HybriMax devices (Flow-through Hybridization HybriMax).
The DNA ploidy analysis kit was from the Beckman Coulter; the flow cytometer was Beckman CytomicsTM FC500. The DNA cell cycle analysis software was also from Beckman Coulter.
The L1 gene methylation level was tested by the methylation-sensitive high resolution melting (MS-HRM). The major instrument was Roche LightCycler type 480 sensitivity analyzer. The completely methylated and unmethylated HPV-16 L1 gene standards of MS-HRM were synthesized (Genscript, Nanjing, China), the specific primers also were synthesized (Genscript, Nanjing, China). The EpiTect Bisulfite Kit and EpiTect HRM PCR Kit were bought from Germany QIAGEN company.
2.3 Experimental procedure
2.3.1 Flow cytometry DNA ploidy analysis
(1) Collected the exfoliative cytology specimens, which were in cell preservation solution. Then through the 300 mesh nylon mesh filter, 1500 r/s centrifugal for 10 minutes, discarded the liquid supernatant, and then repeated this process by adding PBS fluid to the sediment, finally, suspended the exfoliated cells with 1 mL phosphate buffered saline (PBS) solution.
(2) Added 200 μL DNA-Prep LPR reagent into the above solution that blended immediately, and placed it for 5 seconds; then added 2 mL of the DNA-Prep Stain reagent into it. Incubated for 20 minutes in dark place. Last, tested the specimen by Flow Cytometry DNA Ploidy Analysis System of FC500 flow cytometer.
(3) Applied the DNA ploidy analysis software (DNA cell cycle analysis software) to analyze the results and obtained the DNA index (DI) and SPF of each specimen.
2.3.2 Flow-through hybridization and gene chip for HPV genotype test
HPV genotype test was carried out by the steps of HPV GenoArray Diagnostic Kit, which could detect 21 HPV genotypes, including 6, 11, 16, 18, 31, 33, 35, 39, 42, 43,44, 45, 51, 52, 53, 56, 58, 59, 66, and 68 types, and CP8304 types.(1) Extracted the HPV viral DNA by DNA extraction kit.
(2) Took 1 μL of extracted DNA solution and then did PCR amplification according to the instructions in the reaction system by PCR amplification.
(3) Made diversion hybridization amplification for amplified DNA samples.
(4) Made hybridization results analysis of hybrid membrane after coloration; corresponding color parts’ classification is the result.
2.3.3 MS-HRM analysis of the HPV-16 L1 gene
The sequence HPV-16 L1 localized from nucleotide (nt) 5576 to (nt) 5636 (NCBI accession no. NC_001526.2), which contains 4 CpG sites (nt 5602, nt 5608, nt5611, and nt 5617) were tested.1. Mixed the completely methylated and unmethylated HPV-16 L1 gene standards in 0%, 10%, 25%, 50%, 75% and 100% methylated to unmethylated template ratios, which served as the methylation standards for MS-HRM.
2. Extracted the HPV viral DNA by DNA extraction kit.
3. The methylation standards and all extracted HPV viral DNA were bisulfite modificated, the detailed steps referred to the instruction book of EpiTect Bisulfite Kit.
4. The specific PCR primers used were that, forward primer: 5′ GCGCATTATTGTTGATGTAGGTGATTTTTATTTATATTTTAG3′, reverse prime: 5′ GCCGCACTAAACAACCAAAAAAACATCTAAAAAAAAATA 3′. The detailed steps of MS-HRM PCR referred to the handbook of EpiTect HRM PCR.
5. The HRM data were analyzed using the Genescanning Software (Roche).
2.4 Statistical analysis
The result was showed by mean ± standard, if the data were normally distributed; the statistical analysis was processed by SPSS 18.0 software. Comparison of count data models was by chi-square test. Multivariate logistic regression analysis was used to evaluate the risk factors. α = 0.05 is the inspection level, and P < 0.05 was received as having statistical differences.
3 Results
3.1 The general characteristics of 173 cases
The 4 characteristics factors between 2 ethnics were collected and compared such as age, marriage status, childbearing history, and abortion history, which was related to the HPV infection. The detail result is given in Table 1.
Table 1 The general characteristics of 173 cases.
3.2 The HPV infection situation of 173 cases
The HPV-16 infected women were divided into 2 groups in each ethnic women, including single HPV-16 (sHPV-16) infection (only HPV-16 infection) and multiple HPV-16 (mHPV-16) infection (existing HPV-16 infection and other HPV genotype infection at the same time). Then, the differences of infection status between 2 ethnics were compared. The results are shown in Table 2.
Table 2 Comparison of the HPV infection status in Han and Uygur women.
3.3 Comparison of HPV-16 L1 gene methylation in different HPV infection status between Han and Uygur women
The result of L1 gene methylation was divided into 3 grades, including mild methylation group (L1 gene methylation less than 25%), moderate methylation group (L1 gene methylation between 25% and 50%), and severe methylation group (L1 gene methylation more than 50%). The differences between 2 ethnics and 2 HPV-16 infection status were compared. The results are shown in Table 3.
Table 3 Comparison of L1 methylation status between 2 ethnics and 2 HPV-16 infection status.
3.4 Comparison of DNA ploidy in different HPV-16 infection status between Han and Uygur women
The result of DNA ploidy was shown as DI and SPF, DI = 1.10 was the threshold of the DNA ploidy results; if a sample's DI was more than 1.10, it was seen as positive of DNA ploidy analysis, which meant heteroploid. If not, the sample was seen as negative of DNA ploidy analysis. The differences between 2 ethnics and 2 HPV-16 infection status were also compared. The results are shown in Table 4.
Table 4 Comparison of DNA ploidy between 2 ethnics and 2 HPV-16 infection status.
3.5 Comparison of DI, SPF in different L1 gene methylation grades
Because DI and SPF had statistic difference between Han and Uygur women in the same HPV-16 infection status, so respectively compared the DI and SPF in different L1 gene methylation grades to prove that L1 gene methylation effected the DNA ploidy of host cells. The results are shown in Table 5.
Table 5 Comparison of DI, SPF in different L1 gene methylation grades.
3.6 Comparison of HPV-16 L1 gene methylation and HPV-16 infection status in different DNA ploidy status
Because DI or SPF had statistic difference in different L1 gene methylation grades; therefore, respectively further compared the HPV-16 L1 gene methylation and HPV-16 infection status in different DNA ploidy status, the results show in Tables 6 and 7.
Table 6 Comparison of HPV-16 L1 gene methylation and HPV-16 infection status in different DNA ploidy status for Han women.
Table 7 Comparison of HPV-16 L1 gene methylation and HPV-16 infection status in different DNA ploidy status for Uygur women.
3.7 Multifactor analysis between HPV-16 infection status, HPV-16 L1 gene methylation, and heteroploid of DNA ploidy
Because both L1 gene methylation and HPV-16 infection status had statistic differences in different DNA ploidy status for Uygur women or Han women, so respectively discussed the relationship between HPV-16 infection status, HPV-16 L1 gene methylation, and heteroploid of DNA ploidy by logistic regression analysis in Han or Uygur women. The corresponding logistic regression expression was:
For Han women:
For Uygur women:
Tables 8 and 9 show the results of multivariate logistic regression analysis. Therefore, HPV-16 infection status, HPV-16 L1 gene methylation were the risk factors which were significantly associated with increased risk of DNA heteroploid. The odds ratio (OR) is displayed in Figs. 1–3.
Table 8 Results of multivariate logistic regression analysis for Han women.
Table 9 Results of multivariate logistic regression analysis for Uygur women.
Figure 1 The odds ratio of mHPV-16 infection status compared to sHPV-16 infection status for DNA heteroploid in Han and Uygur women. mHPV-16 = multiple HPV-16, sHPV-16 = single HPV-16.
Figure 2 The odds ratio of moderate L1 gene methylation compared to mild L1 gene methylation for DNA heteroploid in Han and Uygur women.
Figure 3 The odds ratio of severe L1 gene methylation compared to mild L1 gene methylation for DNA heteroploid in Han and Uygur women.
4 Discussion
The study researched 173 HPV-16 infected women in Xinjiang region by completely randomized design, including 94 Uygur and 79 Han women. It was found that there were differences in the risk factors of age and childbearing history by analyzing the general characteristics. The age of Uygur infected HPV-16 women was younger than Han women, meanwhile, the Uygur women showed more childbearing time than Han women, all of these fit on the common characteristics of Uygur and Han women in Xinjiang.[17]
The infection status of HPV-16 genotype included sHPV-16 and mHPV-16 infection. In this study, the proportion of mHPV-16 infection in Uygur women was much higher than Han women (61.7% vs 38.0%). So, the mHPV-16 infection was more common in Uygur, because high-risk multiple HPV infection was easy likely to cause the lesion of cervical epithelial cells in the previous report.[15] So, the cervical lesion because of HPV infection also was often occurred. The present study has found that DNA methylation was common in the process of cervical cancer as the molecular biology marks,[18] both host gene methylation and HPV gene methylation played the important role in the process of cervical lesion.[19–21] HPV L1 gene was the coding gene of major capsid protein, it was found that a high level of L1 gene methylation should mean the integration status of HPV genome and host cell genome, the low level of L1 gene methylation proved that HPV genome was in free status from the host cell genome.[8] Bryant et al[22] reported that a consistent trend was existed between HPV L1 gene methylation and cell morphology changes, it could be used as a molecular target of cervical lesions’ diagnosis and treatment. So, L1 gene methylation level not only represented the status of HPV infection in cervical exfoliated cells, but also had a good correction with the cervical cell lesion. HPV-16 L1 gene methylation was tested by MS-HRM in the research, MS-HRM was a promising technology to detect the gene methylation, which could make semiquantitative detection of methylation situation. It also be reported that the MS-HRM was a feasible method to detect HPV-16 L1 gene methylation.[23,24] According to the results of MS-HRM, the degree of the L1 gene methylation was divided into mild, moderate, and severe grades, the methylation status had no significant difference between 2 ethics in the same HPV-16 infection, but it existed significant difference in different HPV-16 status of the same ethnic women. So, L1 gene methylation level was severity as the seriousness of infection status, which was in accordance with the present reports.
Flow cytometry DNA ploidy analysis could reflect the DNA replication of specimens by DI value and SPF value, meanwhile, could indicate the cell lesion by heteroploid situation, when DI and SPF reached the critical value, means the appearance of cell lesion for an abnormal proliferation cells.[25] DI and SPF value had differences between Han and Uygur women neither in sHPV-16 infection nor mHPV-16 infection, but DNA heteroploid had no difference. The phenomenon proved that, compared to Han women, DNA replication of HPV-16 host cells were active in Uygur women, but most cases only stayed in hyperplasia replication active phase, also did not achieve the level of heteroploid. HPV-16 infection as a type of high-risk HPV infection, which could promote the host cell to immortalize, also enhances the activity of cell metabolism in order to make the DNA duplicate activity. When L1 gene methylation degree deepening, which represented the HPV DNA was integrated into the genome of host cell, meant the persistent infection, which was easy to result the DNA heteroploid of host cell. So, combined the results from Table 4 to Table 5, it could be thought that infection status and L1 gene methylation lead to the differences of DNA ploidy between Han and Uygur women.
From Table 6 and Table 7, it proved that infection status and L1 gene methylation could effect the DNA heteroploid, so logistic multifactor regression analysis was respectively done for Han and Uygur women. DNA heteroploid as dependent variable, with infection status and L1 gene methylation grades as potential influence factors, it was explored the risk level of infection status and L1 gene methylation to generate the DNA heteroploid. Infection status and L1 gene methylation were the risk factors to cause DNA heteroploid. When L1 gene methylation unchanged, it was 4.409 times to appear DNA heteroploid in multiple infection than single infection in Han women, in Uygur women, the OR was 3.279, the results accord with previous studies.[15,26] Compared to the Uygur women, HPV-16 infection status seemed to be more influence on Han women (OR: 3.297 vs 4.409). And L1 gene methylation created larger influence on Uygur women than Han women, in the same HPV infection, with a mild degree of L1 gene methylation as reference, Uygur women increase 5.075 and 63.634 times to appear DNA heteroploid when L1 gene methylation changed to moderate and severe grade, but the 2 OR values were 3.313 and 20.592 in Han women, which was smaller than Uygur women.
In a word, the research explored the influence of HPV-16 infection status and HPV-16 L1 gene methylation on DNA ploidy of cervical cell, discovered that both HPV-16 infection status and L1 gene methylation should be the risk factors of DNA ploidy. Especially L1 gene methylation had the greatest influence on the DNA heteroploid of cervical cell in Uygur women, it should be recommended to introduce the L1 gene methylation as a potential index to the existing system of cervical lesion screening and treatment standard of HPV infection in order to provide better serves for the masses of HPV-16 infected women.
Abbreviations: DI = DNA index, HPV = human papillomavirus, mHPV-16 = multiple HPV-16, MS-HRM = methylation-sensitive high resolution melting, OR = odds ratio, sHPV-16 = single HPV-16, SPF = S-phase cells’ peak percentage.
Funding/support: This research was supported by the Natural Science Foundation of Xinjiang Uygur Autonomous Region, People's Republic of China (No. 2015211C133).
The authors have no conflicts of interest to disclose.
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PMC005xxxxxx/PMC5371487.txt |
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Medicine (Baltimore)Medicine (Baltimore)MEDIMedicine0025-79741536-5964Wolters Kluwer Health 28328850MD-D-16-0720710.1097/MD.0000000000006429064296700Research ArticleSystematic Review and Meta-AnalysisMeasurement of exhaled nitric oxide concentration in patients with obstructive sleep apnea A meta-analysisZhang Dongmei MDLuo Jinmei MDQiao Yixian MDXiao Yi MD∗Huang Rong MDZhong Xu MDInsalaco. Giuseppe Department of Respiratory Medicine, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Dongcheng District, Beijing, China.∗ Correspondence: Yi Xiao, Department of Respiratory Medicine, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, No. 1 Shuaifuyuan Street, Dongcheng District, Beijing 100730, China (e-mail: pumch_yixiao@sina.com).3 2017 24 3 2017 96 12 e64291 12 2016 22 2 2017 24 2 2017 Copyright © 2017 the Author(s). Published by Wolters Kluwer Health, Inc.2017This is an open access article distributed under the terms of the Creative Commons Attribution-Non Commercial-No Derivatives License 4.0 (CCBY-NC-ND), where it is permissible to download and share the work provided it is properly cited. The work cannot be changed in any way or used commercially without permission from the journal. http://creativecommons.org/licenses/by-nc-nd/4.0Supplemental Digital Content is available in the text
Abstract
Background:
Exhaled nitric oxide (eNO) has been proposed as a noninvasive measure of airway inflammation. However, its value in patients with obstructive sleep apnea (OSA) is still controversial. The authors aim to assess the difference in eNO levels between patients with OSA and controls by a meta-analysis.
Methods:
A systematic search was performed in the PubMed, EMBASE, the Cochrane Library, and MEDLINE databases to collect relevant studies published from 1996 to 2016. Eligible studies that reported eNO levels in patients with OSA were included. STATA (version 12.0) was used for data analysis.
Results:
Two hundred eighty-four studies were reviewed for inclusion, with 16 studies pooled for analysis (16 studies for fractional exhaled nitric oxide [FENO], 5 for alveolar nitric oxide [CANO], and 4 for the maximum airway wall flux of nitric oxide [J′awNO]). The FENO levels were significantly higher in patients with OSA compared with that in the control groups (6.32 ppb, 95% confidence interval [CI] 4.46–8.33, P < 0.001). Furthermore, FENO was significantly increased (4.00 ppb, 95% CI 1.74–6.27, P = 0.001) after overnight sleep in patients with OSA, but not in healthy controls. Additionally, long-term continuous positive airway pressure (CPAP) therapy reduced FENO levels (−5.82 ppb, 95% CI −9.6 to −2.01, P < 0.001). However, the CANO (−0.01 ppb, 95% CI −1.66 to 1.64, P = 0.989) and J’awNO levels (220.32 pl/s, 95% CI −49.31 to 489.94, P = 0.109) were not significantly different between the OSA groups and non-OSA groups.
Conclusion:
The results of the meta-analysis suggest that OSA is significantly associated with airway inflammation and elevated FENO levels can be modified by long-term CPAP therapy. J’awNO and CANO levels were not significantly different between the OSA groups and control groups.
Keywords
airway inflammationcontinuous positive airway pressureexhaled nitric oxideobstructive sleep apneaOPEN-ACCESSTRUE
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1 Introduction
Obstructive sleep apnea (OSA) is a common sleep disorder characterized by repetitive episodes of upper airway obstruction during sleep leading to significant hypoxemia and frequent arousals. With a high prevalence, ranging from 9% to 38% in the overall population,[1] OSA is increasingly regarded as a public health concern because it is closely associated with cardiovascular disorders.[2] Because an altered upper airway structure and function is 1 etiology of OSA,[3,4] local pathophysiological processes such as upper airway inflammation could amplify these abnormalities and may further compromise upper airway patency during sleep. A large body of experimental evidence indicates that patients with OSA present with airway inflammation[5,6] mainly because of the mechanical trauma of recurrent snoring and oxidative stress. Furthermore, it has been reported that the repetitive hypoxia/reoxygenation phenomenon increases the levels of reactive oxygen species, which aggravate vascular endothelium injury in patients with OSA.[7] Therefore, an assessment of respiratory inflammation might be a predictor of OSA and its complications.[8]
Exhaled nitric oxide (eNO) levels have been suggested as a simple, noninvasive, and reproducible marker of respiratory inflammation.[9] Nitric oxide (NO) is a molecule synthesized by NO synthase (NOS). eNO derived from the central airway and alveolus can be separately assessed by obtaining measurements at different flow rates.[10] Fractional exhaled nitric oxide (FENO) reflects bronchial NO production and diffusion, the maximum airway wall flux of NO (J′awNO) represents NO from the airway tree, and alveolar NO (CANO) represents the steady-state alveolar NO concentration.[11] In the lungs, NO regulates pulmonary vascular tone and reduced NO levels may be associated with the development of pulmonary hypertension by contributing to pulmonary vascular smooth muscle proliferation and remodeling.[12] Hypoxia may impair NO release by reducing substrate availability or by inhibiting NOS. Increased levels of eNO are indicative of lung inflammation by over-expression of the inducible NOS, as observed in asthma,[13] while reduced eNO levels can be found in cardiovascular disorders such as pulmonary hypertension,[14] due to decreased NOS expression and activity caused by endothelial dysfunction. In patients with OSA, both principal pathological processes, hypoxia and endothelial dysfunction, coexist and may change eNO concentrations.
In the last 20 years, several studies measuring eNO levels in patients with OSA have been reported, but the results are controversial. Different studies have found increased eNO levels,[15–26] no significant difference,[27–30] or decreased eNO levels[31] in patients with OSA compared with healthy controls. Therefore, the aim of this meta-analysis was to evaluate the potential association between OSA and eNO levels. Our secondary purpose was to review the potential influence of OSA on the severity of airway inflammation to address the question of whether eNO can be a predictor of the diagnosis of OSA or a marker of treatment efficacy.
2 Materials and methods
2.1 Data sources and study selection
We searched for relevant articles in the following databases: PubMed, MEDLINE, EMBASE, and the Cochrane Library. Even though MEDLINE is a component of PubMed, they differ in update frequency and retrieval mechanism; we thus treated them as separate databases to avoid miss any eligible studies. The details of the search strategy are included in the supplementary material (Supplementary Digital Content 1). Briefly, we searched for the terms (“obstructive sleep apnea” or “apnea” or “hypopnea” or “OSA”) and (“FENO” or “exhaled nitric oxide” or “fractional exhaled nitric oxide” or “CANO” or “alveolar NO” or “J’awNO”) and in articles published from 1996 to 2016. Moreover, the references of the retrieved articles were checked, and the PubMed function “related articles” was used to identify additional papers. Two authors reviewed all abstracts independently to determine the eligibility criteria or establish the appropriateness of the research issue. Any disagreements were resolved by discussion with a third reviewer. All levels of evidence were considered, but because of a lack of higher levels of evidence, only controlled trials were included. Studies were included if they met the following criteria: All patients with OSA were newly diagnosed by polysomnography (PSG); patients with OSA and eligible controls had no history of asthma, rhinitis, or sinusitis, and none of them had an allergic disease or were receiving anti-inflammatory medications at the time of the study. All subjects were over 16 years old. Studies were excluded if they were case reports, editorials, reviews, or abstracts. Details of the exclusion criteria can be seen in Fig. 1.
Figure 1 Flow diagram of the literature search.
2.2 Data extraction and analysis
The following information was extracted from the included studies: name of first author, year of publication, country, sample size, age, gender, diagnostic standard for OSA, type of study, and eNO measurement (method, parameters, and expiratory flow rates). When pertinent data were not included in a published article, the corresponding author was contacted to seek clarification. If the data could not be acquired, the article was excluded. The data were extracted by 2 authors independently. All data were expressed as mean ± standard deviation. For studies with data reported in median and range, or median and interquartile range, the mean and standard error were calculated utilizing the methods outlined by Hozo et al.[32]
For studies in which patients with OSA were compared with more than 1 group of control patients (e.g., obese and nonobese controls), only the one that was a better match for the patients with OSA in the study was included in the meta-analysis. For example, Petrosyan et al[33] compared FENO levels in obese patients with OSA with 2 control groups, obese controls and nonobese controls; we only extracted the data of the obese controls because the mean body mass index (BMI) in this group was not significantly different to that in the OSA group. Similarly, Foresi et al[31] compared patients with OSA with 2 control groups, but the hypertension group did not undergo PSG, so we included only the data of the healthy controls. For studies measuring eNO at different times, we used the parameters measured in the morning for our analysis. If eNO was measured at multiple flow rates, we extracted the data for an approximately 50-mL/s flow rate.
Heterogeneity was assessed by calculating the I2 statistics. An I2 of 25% to 49% was considered to represent a low level of heterogeneity, 50% to 74% a moderate level, and 75% to 100% a high level. Due to the high level of heterogeneity presented, a random-effects model was employed to combine the effect size. All statistical analysis was performed using STATA version 12.0 (Stata Statistical Software, College Station, TX). A meta-regression analysis was also performed to assess the influence of study-related factors on the outcomes and analysis of heterogeneity. Publication bias was checked by funnel plots, Begg test, and Egger test. A 2-sided P value ≤ 0.05 was considered statistically significant.
3 Results
3.1 Search results and study characteristics
The search identified 284 potential studies, 267 of which were excluded as described in Fig. 1. Seventeen studies were included in the analysis, but 1 study[34] had obvious publication bias and was excluded from the final meta-analysis. The remaining 16 studies differed in their study design: 5 were cross-sectional trials (CSTs) and 11 were case–control trials (Table 1). The number of patients included in the studies ranged from 13 to 97 in the OSA groups (total 688) and from 7 to 53 in the control groups (total 366). Among the studies, the mean age of participants ranged from 37 to 66 years in both the groups, and generally, more than half of them were male (Table 1). Among the included studies, 7 also analyzed the effects of continuous positive airway pressure (CPAP) treatment on airway inflammation: 2[24,31] evaluated the effects of short-term (2 nights) CPAP therapy while the other 5[21,22,26,30,33] followed CPAP treatment for more than 1 month. A total of 5 studies[21,24,25,29,31] including 359 subjects were pooled for CANO analysis, and 4 studies[21,24,25,29] with 296 subjects were pooled for J’awNO analysis.
Table 1 Characteristics of included studies.
All the studies scored well in terms of adequate descriptions of selection criteria and reference tests, and the availability of clinical data. All included studies clearly described the data source, and patient inclusion and exclusion criteria, and presented measurements for the primary study end points.
3.2 FENO
Because there was heterogeneity in this endpoint (I2 = 82.8%), the random-effects model was used to combine the effect size. The pooled mean difference was 6.39, which indicates that FENO levels in the OSA group were 6.39 ppb (95% confidence interval [CI] 4.46–8.33, P < 0.001) higher than that in the control group (Fig. 2).
Figure 2 Comparison of fractional exhaled nitric oxide levels between obstructive sleep apnea groups and control groups in the 16 included studies.
Subgroup analyses were conducted based on BMI, age, apnea–hypopnea index (AHI), smoking status, and expiratory flow rate. In all subgroups, FENO levels were higher in the patients with OSA than they were in the controls, with a weighted mean difference (WMD) ranging from 3.49 ppb to 8.27 ppb (Supplemental Fig. 1A–C, Supplemental digital Content 2, which shows the results of the subgroup analyses). However, significant heterogeneities still existed in these subgroups (I2 41.7–92.0%).
In 5 studies,[16,22,25,28,29] exhaled NO was measured separately before and after overnight PSG to evaluate the variation of FENO levels in the morning and in the evening. For these studies, 2 analyses were performed. The first analysis was performed with the baseline parameters of morning and evening FENO levels in the patients with OSA and controls. The pooled WMD was 4.00 ppb (95% CI 1.74–6.27, P = 0.001) in the OSA groups compared with 0.29 ppb (95% CI −1.84 to 2.42, P = 0.791) in the control groups (Fig. 3). The second analysis included the changes after PSG (FENO levels in the morning minus FENO levels in the evening) in the OSA groups and controls, and the WMD was calculated to be 3.91 ppb (95% CI 0.55–7.28, P = 0.022), which indicated that in patients with OSA, the overnight increase of FENO levels was larger than that in non-OSA controls. There was medium heterogeneity in this endpoint (I2 = 65.3%) (Fig. 3).
Figure 3 Variation of fractional exhaled nitric oxide (FENO) levels.
The random-effects analysis revealed that long-term CPAP therapy promoted a significant decrease in FENO levels (−5.82 ppb, 95% CI −9.64 to −2.01, P < 0.001; Fig. 4). However, short-term CPAP could not reduce FENO (−3.99 ppb, 95% CI −19.56 to 11.59, P = 0.616; Fig. 4). There was significant heterogeneity due to the limited number of trials, with an I2 of 81.6% and 94.2%, respectively.
Figure 4 Effect of continuous positive airway pressure (CPAP) treatment on fractional exhaled nitric oxide levels.
3.3 CANO and J’awNO
For CANO, a random-effects analysis was applied since there was evidence of heterogeneity among the 5 studies (I2 = 96.1%, P < 0.001). The calculated WMD (−0.01 ppb, 95% CI −1.66 to 1.64, P = 0.989; Fig. 5) indicated that there was no statistical difference in the CANO levels between the OSA groups and control groups.
Figure 5 Comparison of concentration of alveolar nitric oxide between the obstructive sleep apnea groups and control groups in the 5 included studies.
For J’awNO, the pooled WMD was 220.32 pl/s (95% CI −49.31 to 489.94, P = 0.109). There was heterogeneity in this analysis (I2 = 74.2%, P = 0.009; Fig. 6).
Figure 6 Comparison of the maximum airway wall flux of nitric oxide between the obstructive sleep apnea groups and control groups in the 4 included studies.
3.4 Publication bias
The funnel plot was almost perfectly symmetrical (Fig. 7) after excluding the study by Devouassoux et al,[34] suggesting that this study might have publication bias. The bias might have been caused by the inclusion of subjects with allergies. Subsequently, Begg tests (P = 0.822) and Egger tests (P = 0.463) were performed and found no evidence of publication bias in the remaining 16 studies. For the analysis of CANO levels and J’awNO levels, the Begg tests (P = 0.806 and P = 0.734, respectively) and Egger tests (P = 0.391 and P = 0.862, respectively) also found no evidence of bias.
Figure 7 Funnel plot of fractional exhaled nitric oxide.
3.5 Sensitivity analysis
No single trial, when removed, significantly affected the overall estimate of the effects of the 3 eNO measures (Supplemental Fig. 2A–C, Supplemental digital Content 3, which shows the results of the sensitivity analyses). The pooled analysis using the random-effects model showed that FENO levels were increased significantly (WMD 6.39, 95% CI 4.46–8.33, P < 0.001). The fixed-effects model found a similar result (WMD 5.56, 95% CI 4.93–6.20, P < 0.001). After including the previously excluded study, the pooled analysis result was 7.25 (95% CI 3.49–11.00, P < 0.001) using the random-effects model.
3.6 Meta-regression analysis
Meta-regression analyses were performed to evaluate the effect of age, BMI, AHI, and minimum pulse oxygen saturation (SpO2) on the levels of FENO. The FENO levels were not significantly correlated with the age of the patients with OSA (P = 0.980) and BMI (P = 0.438), the age (P = 0.353) and BMI of normal participants (P = 0.362), or the AHI (P = 0.399) and minimum SpO2 (P = 0.964). The analyses of CANO levels and J’awNO levels described above were not reanalyzed by meta-regression because of the limited number of studies included.
4 Discussion
NO is a reactive molecule produced by nitric oxide synthase (NOS) in a reaction that converts l-arginine and oxygen to citrulline and NO. Three distinct forms of NOS have been identified: endothelial NOS (eNOS), neuronal NOS (nNOS), and inducible NOS (iNOS).[35] Among them, only iNOS can produce a large amount of NO for longer periods of time after activation by stimuli; it plays a role in pathophysiological processes such as inflammation. Exhaled NO levels are elevated in conditions associated with airway inflammation, for example, asthma, and are used as simple, noninvasive markers of airway inflammation.
To our knowledge, this is the first meta-analysis addressing the exhaled NO levels in patients with OSA. We found that there was an increase in FENO levels in subjects with OSA; however, CANO and J’awNO were not significantly different between the patients with OSA and the controls. Moreover, FENO levels were significantly increased on waking up in patients with OSA, but not in non-OSA groups, and long-term CPAP was able to modify FENO in OSA groups.
Our results showed that FENO was significantly increased in subjects with OSA, and that this might be linked to the over-expression of iNOS,[15,17,36] which was partially reversible after long-term CPAP treatment. In our pooled analysis, the level of FENO on waking up was significantly increased in subjects with OSA (Fig. 3) but not in healthy controls. Mechanical stress on the mucosa caused by intermittent airway closure and reopening as well as ischemia-reperfusion injury from intermittent nocturnal hypoxemia produces oxygen free radicals, which can lead to increased upper airway inflammation. The nasal, tonsillar, and oropharyngeal tissues are potential inflammatory sites in patients with OSA,[37–40] and plasma cell infiltration and interstitial edema have been documented in tissue biopsies.[40] Local upper-airway inflammation promotes oropharyngeal inspiratory muscle dysfunction and the formation of progressive local neurogenic lesions, thus amplifying the upper airway narrowing and collapsibility.[41] Additionally, tissue biopsies confirmed the significant effect of long-term CPAP treatment on reducing inflammation-related infiltration in upper airways.[38] Thus, FENO can be used as a simple, noninvasive marker of upper airway inflammation in patients with OSA, allowing a more accurate prediction of response to treatment.
Experimental studies have found that other exhaled markers of airway inflammation and oxidative stress such as interleukin 6, interleukin 10, and 8-isopentane were also raised in the breath condensate of adults with OSA,[42,43] and that there was a significantly higher percentage of neutrophils in the induced sputum of patients with OSA than in healthy volunteers.[6,18,34] These findings may suggest lower airway inflammation in patients with OSA. However, our results indicate that J’awNO is not a marker of lower airway inflammation in patients with OSA.
The CANO levels reflect the balance between the local production of NO from distal parts of the lung and diffusion across the alveolar capillary wall. Increased CANO has been found in patients with asthma,[44] alveolitis,[10] and chronic obstructive pulmonary disease,[45] mainly due to the increased NO production by inflammatory cells, epithelium, or endothelial cells. Although OSA is associated with systemic inflammation, increased oxidative stress, and endothelial dysfunction, we speculate that the extent of these processes was not enough to alter the concentration of CANO, as demonstrated by the lack of a significant difference in CANO levels between the OSA and control subjects. An alternative explanation might be the presence of endothelial dysfunction in patients with OSA; unfortunately, none of the included studies investigated this issue. The CANO levels in patients with OSA should be further investigated and characterized.
In the meta-regression, both the characteristics (age and BMI) and OSA severity (AHI and minimum SpO2) had no correlation with the increased FENO levels. In another experiment by Verhulst et al[46] involving the pediatric population, habitual snoring and age were the only variables associated with raised FENO levels in the morning and afternoon, leading them to conclude that snoring is more important than the actual obstructive respiratory events for increased upper airway inflammation. They proposed that snoring induced vibration of the soft tissues, which caused damage to these tissues contributing to the pathogenesis of OSA. In our analysis, only FENO was significantly different between the OSA and control subjects, implying that mechanical damage may play a more important role in the upper airway inflammation than that of hypoxemia. This hypothesis needs to be confirmed in further studies. Notably, even though FENO levels increased after sleep in patients with OSA, their FENO levels were still around the upper limit of the normal range (25 ppb). Therefore, FENO might not be an effective predictor of diagnosis of OSA, especially for distinguishing suspected OSA and the pure snorers.
The observed heterogeneity might be explained by the differences in patient inclusion criteria and the time of exhaled NO measurement. Further, only some of the studies included smokers. In the study by Fortuna et al,[21] currently smoking patients had lower FENO and CANO levels than ex-smokers and nonsmokers, possibly because cigarettes contain a large number of free radicals and pro-oxidant substances, which cause lower NO bioactivity, and the fact that smokers have a tetrahydrobiopterin deficit, which reduces the generation of NO.[47] However, in Liu et al's study,[24] FENO and CANO were not significantly different between the smokers and nonsmokers in both the OSA group and the healthy controls. Most studies measured the eNO from 6 am to 10 am and between 8 pm to 11 pm, a few studies did not report the measurement time,[17] and 1 study only evaluated the eNO from 11 am to 1 pm.[33] Dias et al confirmed that patients with OSA and healthy subjects showed a circadian pattern of FENO with a decrease of values across the day,[19] suggesting that the time of measurement may be a confounder in this analysis. Finally, some baseline data, such as age, BMI, and AHI, were significantly different between groups.
5 Limitations
Despite these meaningful findings, several limitations of this meta-analysis still need to be emphasized. Firstly, the available literature is largely low-level evidence; either case–control or CSTs of a relatively small size. Secondly, different techniques and instruments were used for the measurement of exhaled NO, which could be another source of study heterogeneity. Thirdly, there was also heterogeneity across the sample populations. We could not perform meta-regression for other confounding factors—snoring[25] or time of measurement[19]—since we did not have enough data on these variables. These factors have previously been found to be associated with eNO levels.
6 Conclusion
Our findings suggest that OSA was significantly associated with elevated FENO levels, especially after waking up, and long-term CPAP therapy can reduce FENO levels. Accordingly, FENO levels might be a noninvasive marker of upper airway inflammation in patients with OSA. However, J’awNO and CANO are not useful markers of airway inflammation for patients with OSA.
Supplementary Material
Supplemental Digital Content
Acknowledgments
The authors would like to thank Xiaolu Gao for her help in the statistical analyses and developing the methods for performing the meta-analysis.
Abbreviations: AHI = apnea–hypopnea index, BMI = body mass index, CANO = concentration of alveolar nitric oxide, CI = confidence interval, CPAP = continuous positive airway pressure, CST = cross-sectional trail, eNO = exhaled nitric oxide, eNOS = endothelial nitric oxide synthase, FENO = fractional exhaled nitric oxide, iNOS = inducible nitric oxide synthase, J′awNO = the maximum airway wall flux of nitric oxide, nNOS = neuronal nitric oxide synthase, NO = nitric oxide, NOS = nitric oxide synthase, OSA = obstructive sleep apnea, PSG = polysomnography, SpO2 = pulse oxygen saturation, WMD = weighted mean difference.
Since it was a meta-analysis, it did not require ethical approval or patient consent.
Conceived and designed the experiments: YX, DZ, and JL; Performed the studies search and data integrity: DZ, YQ, and RH. Analyzed the data: JL, YX, RH, and XZ. Contributed reagents/materials/analysis tools: all authors. Wrote the paper: all authors.
This study was supported by the National Natural Science Foundation of China (81570085)
The authors have no conflicts of interest to disclose.
Supplemental Digital Content is available for this article.
==== Refs
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PMC005xxxxxx/PMC5371490.txt |
==== Front
Medicine (Baltimore)Medicine (Baltimore)MEDIMedicine0025-79741536-5964Wolters Kluwer Health 28328853MD-D-16-0704510.1097/MD.0000000000006437064376600Research ArticleSystematic Review and Meta-AnalysisUpdated association of tea consumption and bone mineral density A meta-analysisZhang Zhao-Fei MD∗Yang Jun-Long MMJiang Huan-Chang MMLai Zheng MMWu Feng MMLiu Zhi-Xiang MDDesapriya. Ediriweera Department of Orthopedic Surgery, Huadu District People's Hospital of Guangzhou, Guangdong, China.∗ Correspondence: Zhao-Fei Zhang, Department of Orthopedic Surgery, Huadu District People's Hospital of Guangzhou, Guangdong 510800, China (e-mail: hanyangzzf@163.com).3 2017 24 3 2017 96 12 e643723 11 2016 22 2 2017 22 2 2017 Copyright © 2017 the Author(s). Published by Wolters Kluwer Health, Inc.2017This is an open access article distributed under the terms of the Creative Commons Attribution-Non Commercial License 4.0 (CCBY-NC), where it is permissible to download, share, remix, transform, and buildup the work provided it is properly cited. The work cannot be used commercially without permission from the journal. http://creativecommons.org/licenses/by-nc/4.0Abstract
Background:
Current studies evaluating the association of tea consumption and bone mineral density (BMD) have yielded inconsistent findings. Therefore, we conducted a meta-analysis to assess the relationship between tea consumption and BMD.
Methods:
The PubMed, Embase, and Cochrane Library databases were comprehensively searched, and a meta-analysis performed of all observational studies assessing the association of tea consumption and BMD. Forest plots were used to illustrate the results graphically. The Q-test and I2 statistic were employed to evaluate between-study heterogeneity. Potential publication bias was assessed by the funnel plot.
Results:
Four cohort, 1 case–control, and 8 cross-sectional studies including a total of 12,635 cases were included. Tea consumption was shown to prevent bone loss [odds ratio (OR): 0.66; 95% confidence interval (CI), 0.47–0.94; P = 0.02], yielding higher mineral densities in several bones, including the lumbar spine [standardized mean difference (SMD): 0.19; 95% CI, 0.08–0.31; P = 0.001], hip (SMD: 0.19; 95% CI, 0.05–0.34; P = 0.01), femoral neck [mean difference (MD): 0.01; 95% CI, 0.00–0.02; P = 0.04], Ward triangle (MD: 0.02; 95% CI, 0.01–0.04; P = 0.001), and greater trochanter (MD: 0.03; 95% CI, 0.02–0.04; P < 0.00001), than the non-tea consumption group.
Conclusion:
This meta-analysis provided a potential trend that tea consumption might be beneficial for BMD, especially in the lumbar spine, hip, femoral neck, Ward triangle, and greater trochanter, which might help prevent bone loss.
Keywords
bone mineral densitymeta-analysisosteoporosistea consumptionOPEN-ACCESSTRUE
==== Body
1 Introduction
Osteoporosis, a serious hazard to human health,[1] is a systemic skeletal disease caused by decreased bone mass and micro-architectural degradation of the bone tissue; it produces increasing physical illness and pain.[1–5] Bone mineral density (BMD) is a major indicator of osteoporosis, and determines its severity.
Tea is the most popular beverage in the world; the health advantages of this beverage have been reported in cardiovascular diseases, rheumatoid arthritis, influenza, and cancer.[6–10] The association of tea consumption with BMD has been investigated since the 1990s.[11] However, previous studies have yielded inconsistent conclusions. Indeed, some researchers claim a positive relationship between tea consumption and BMD,[12–14] while others support an inverse relationship between them.[11] Meanwhile, no correlation was found in some studies.[15–17]
To clarify the relationship of tea consumption and BMD more exactly and systematically, a meta-analysis of all available studies was performed.
2 Methods
2.1 Literature search
Electronic databases, including Embase, PubMed, and Cochrane Library, were searched comprehensively for all relevant literature, without restriction to regions, languages, or publication types. The following MeSH-free words and their combinations were searched in all fields: ((“Tea” [MeSH]) or (“Tea” [Free words])) AND (((“Osteoporosis” [MeSH]) or (“Osteoporosis” [Free words])) or ((“Bone Density” [MeSH]) or (“Bone Density” [Free words]))). In addition, the reference lists of the selected literature were also used to expand the search. Two investigators independently searched for articles, and reviewed all the retrieved studies. Disagreement between the 2 investigators was resolved by consensus, involving a third reviewer.
2.2 Inclusion and exclusion criteria
Inclusion criteria were as follows: observational studies with cohort, case–control, and cross-sectional designs, respectively (there was no relevant double-blind, placebo controlled trials); tea consumption as exposure; BMD or osteoporosis as outcome; results including means and standard deviations or dichotomous data, or providing sufficient information to derive the latter. Exclusion criteria were reviews, repeated, or overlapped publications; herbal tea; no measurement locations of BMD; animal studies; and studies with unavailable data.
2.3 Data extraction
Relevant information from each eligible study was extracted independently by 2 reviewers (Zhang and Yang) using a standardized form. Information included study name (first author), publication year, study location, study design, sample size, tea type, measurement locations of BMD, and study results.
2.4 Quality assessment
The Newcastle–Ottawa scale (NOS), with scores of 0 to 9 (allocated as stars), was used to assess the methodological quality of cohort and case–control studies,[18,19] and high quality was considered for articles with 6 or more stars. In addition, cross-sectional studies were assessed by an 11-item checklist recommended by Agency for Healthcare Research and Quality (AHRQ).[20] An “UNCLEAR” or “NO” answer conferred a score of “0” to the item, and “YES” a score of “1.” The quality of the article was assessed as follows: low quality, 0 to 3; medium quality, 4 to 7; high quality, 8 to 11.[20]
2.5 Ethical statement
All results and analyses were from previous published studies; thus, no ethical approval and patient consent are required.
2.6 Statistical analysis
All statistical analyses were performed with Review Manager 5.3 (The Cochrane Collaboration, Copenhagen, Denmark). In the pooled results, mean difference (MD) and odds ratio (OR) were used to compare continuous and dichotomous variables, respectively; standardized MD (SMD) were used for different units. All results were expressed with 95% confidence interval (CI). Heterogeneity was measured by the Q-test with I2 statistics, with P < 0.10 and I2 > 50% indicating high heterogeneity.[21,22] The random-effects model was used, when there was significant heterogeneity between-studies; otherwise, the fixed-effects model was employed.[23] Sensitivity analyses were used to evaluate the impact of each study on the pooled results by removing each study in turn,[10,24] assessing whether the quality of articles affected the overall results.[25] Funnel plots were used to assess potential publication bias.
3 Results
3.1 Study selection
A total of 364 relevant articles were obtained in the initial literature search. Then, 82 articles were excluded because of duplication; 248 others which were obviously irrelevant, reviews, or animal studies were also excluded by screening titles or abstracts. Studies with unavailable data or assessing herbal tea were also removed after full text reading. Finally, 13 articles were included in this study, evaluating 12,635 cases (6059 and 6576 individuals in the tea- and non-tea consumption groups) (Fig. 1).
Figure 1 Flow diagram of screened, included, and excluded studies.
3.2 Characteristics of the included studies
Ten studies were from PubMed, 3 from Embase, and none from the Cochrane Library. All included articles had available full texts. There were 5 studies with count data (3 and 2 studies with ordinal and dichotomous data, respectively)[26–30]; 9 studies had continuous data,[13,14,17,30–35] with, 1 presenting both dichotomous and continuous data.[30] Besides, for continuous data, BMD values of the femoral neck, Ward triangle, greater trochanter, total body, intertrochanteric hip, lumbar spine, hip, and phalanges were presented in the 9 studies. No further evaluation study was found in the reference lists of these studies. In addition, the reference lists of relevant articles did not produce further studies for evaluation. The characteristics of all studies are presented in Tables 1 and 2.
Table 1 Characteristics of included studies (continuous data).
Table 2 Characteristics of included studies (dichotomous data).
3.3 Meta-analysis results
Data from 5 studies with dichotomous variables (1 study both dichotomous and continuous data), including 1398 and 696 in the tea- and non-tea consumption groups, were assessed in this meta-analysis. Two of the studies claimed tea consumption to have a beneficial impact on BMD compared with non-tea consumption[28,29]; no correlation between them was found in the remaining 3 studies.[26,27,30] The pooled results showed that tea consumption could reduce the occurrence of low bone mass (OR = 0.66, 95% CI = 0.47–0.94, P = 0.02) (Fig. 2).
Figure 2 Forest plot and meta-analysis of dichotomous variables. CI = confidence interval, M-H = Mantel-Haenszel method.
We also performed a meta-analysis for continuous variables according to BMD at different locations in the 9 studies.[13,14,17,30–35] The pooled results showed that BMD values of the femoral neck (MD: 0.01, 95% CI, 0.00–0.02; P = 0.04), Ward triangle (MD: 0.02, 95% CI, 0.01–0.04, P = 0.001), greater trochanter (MD: 0.03, 95% CI, 0.02–0.04, P < 0.00001), lumbar spine (SMD: 0.19, 95% CI, 0.08–0.31, P = 0.001), and hip (SMD: 0.19, 95% CI, 0.05–0.34, P = 0.01) were higher in the tea consumption group than in the non-tea consumption group (Figs. 3 and 4). However, no statistically significant differences in BMD values of the total body (MD: 0.00, 95% CI, -0.00 to 0.00, P = 0.06), intertrochanteric hip (MD: 0.02, 95% CI, -0.01 to 0.05, P = 0.06), and phalanges (SMD: 0.25, 95% CI, -0.02 to 0.52, P = 0.07) were obtained (Figs. 3 and 4).
Figure 3 Forest plot and meta-analysis of BMD in the femoral neck, Ward triangle, greater trochanteric, total body, and intertrochanteric hip. CI = confidence interval, IV = inverse variance method, SD = standard deviation.
Figure 4 Forest plot and meta-analysis of BMD in the lumbar spine, hip, and phalanges. ; CI = confidence interval, IV = inverse variance method, SD = standard deviation.
3.4 Sensitivity and publication bias
Sensitivity analysis was performed by sequentially excluding each study in order to examine the influence of individual studies on the overall assessment. Interestingly, none of the studies fairly affected the overall findings. In addition, sensitivity analysis was conducted to access high-quality studies, and the results did not obviously change. Figure 5 shows a funnel plot for continuous variables, with slight asymmetry.
Figure 5 Funnel plot. SE = standard error, SMD = standardized mean difference.
4 Discussion
Tea is the most frequently consumed beverage in daily life, and its protective or harmful impacts on human health are a major public issue. This was the first meta-analysis to address this subject. Our analysis of 4 cohort, 1 case–control, and 8 cross-sectional studies with 12,635 cases indicated a potential trend that tea consumption might result in higher BMD at the femoral neck, Ward triangle, greater trochanter, lumbar spine, and hip than non-tea consumption, and might prevent bone loss.
These findings corroborate many other studies.[12,36,37] For instance, a study including 2016 cases reported that tea consumption has protective effects on the femoral neck and lumbar spine with T scores >–0.75.[36] In addition, Hoover et al[12] conducted a study of 62 postmenopausal women, and found that tea consumption yields 10% and 14% higher BMD values in the lumbar spine and femoral neck, respectively, than the non-tea consumption group. Similar results were found in animal experiments. Indeed, studies showed that tea polyphenols increase femoral BMD of female rats.[38–41] However, others reported that tea consumption has no effect on BMD.[11,42] Hernández et al[11] found no association of tea consumption with BMD, and even an inverse correlation. In addition, a study evaluating 201 cases with osteoporosis or osteopenia in Turkey reported no association of tea consumption with BMD of the lumbar spine, and a negligible correlation with the femoral neck.[42] The above 2 studies, which were not adjusted, were inconsistent with our series. Besides, a prospective randomized controlled study also found no correlation between tea and BMD,[43] the main reason likely being the small sample size.
Tea polyphenols contain abundant epigallocatechin gallate (EGCG) as the main component of tea.[44,45] EGCG has been widely studied. Its beneficial effects on bone formation are mainly through increasing alkaline phosphatase activity at both the protein and gene expression levels in osteoblastic-like cells, including SaOS-2 cells[46] and MC3T3-E1 cells, and increased formation of mineralized bone.[47] Moreover, tea polyphenols significantly promote osteoblastic survival and decrease osteoblastic apoptosis,[46] thereby leading to elevated cell proliferation and differentiation.[48] This was the theoretical basis of our research.
In this meta-analysis, no correlation was found between tea consumption and BMD of the whole body, intertrochanteric hip, and phalanges. This finding might be unreliable because only 1 or 2 studies assessing these entities were included. Meanwhile, 5 studies of dichotomous variables were included in this meta-analysis; the pooled results indicated that tea consumption could prevent bone loss. However, we did not analyze the effects of tea consumption on BMD at each location due to insufficient data provided in the above 5 studies.
Means and standard deviations were not provided for continuous data in some included articles; means and standard deviations were derived on the basis of the Cochrane Handbook. Furthermore, other studies provided ordinal data, such as normal, osteopenia, and osteoporosis; osteopenia and osteoporosis were combined into low bone mass to generate dichotomous data, as they all belong to bone mass reduction; the pooled results were similar to those of continuous data. In addition, considering that T values reflect the true levels of BMD, we included 2 studies that provided only T values.[30,33] We combined T values with BMD values using SMD, and only BMD values using MD.
Next, we performed sensitivity analysis, including only high-quality studies in order to evaluate any impact of study quality on the effect estimates. The results did not change obviously. Consequently, the low-quality studies included had no significant effects on the overall results. Moreover, between-study heterogeneity was not significant for dichotomous and continuous variables, but significant for the lumbar spine and hip. The main reason for the heterogeneity might be from different locations, populations, tea types, or study designs. These studies used the random-effects model to reduce the effect of heterogeneity; however, it was not eliminated.
This meta-analysis had the following limitations that must be taken into account. First and foremost, it included a limited number of observational trials with some being low and medium-quality studies, which might result in selective and performance bias owing to the absence of random allocation, allocation concealment, and blinding. Secondly, subgroup analysis of age, tea types, and tea in cups was not performed because of few included studies.
In summary, these findings provide a potential trend of beneficial effects of tea consumption on BMD, especially in the lumbar spine, hip, femoral neck, Ward triangle, and greater trochanter, which might help prevent bone loss.
Abbreviations: AHRQ = Agency for Healthcare Research and Quality, BMD = bone mineral density, CI = confidence interval, EGCG = epigallocatechin gallate, MD = mean difference, NOS = Newcastle–Ottawa scale, OR = odds ratio, SMD = standardized mean difference.
The authors report no conflicts of interest.
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PMC005xxxxxx/PMC5371494.txt |
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Medicine (Baltimore)Medicine (Baltimore)MEDIMedicine0025-79741536-5964Wolters Kluwer Health 28328857MD-D-16-0653810.1097/MD.0000000000006449064494800Research ArticleObservational StudyIVC filters—Trends in placement and indications, a study of 2 populations Shah Mahek MDa∗Alnabelsi Talal MDbPatil Shantanu MDbReddy Shilpa MDcPatel Brijesh DOaLu Marvin MDbChandorkar Aditya MDbPerelas Apostholos MDbArora Shilpkumar MDdPatel Nilay MDeJacobs Larry MDaEiger Glenn G. MDfTarantino. Giovanni a Department of Cardiology, Lehigh Valley Hospital, Allentownb Department of Medicinec Department of Radiology, Einstein Medical Center, Philadelphia, PAd Mount Sinai St Luke's-Roosevelt Hospital, New York, NYe Saint Peter's University Hospital, New Brunswick, NJf Division of Pulmonary and Critical Care, Einstein Medical Center, Philadelphia, PA.∗ Correspondence: Mahek Shah, Lehigh Valley Health Network, 1250S Cedar Crest Blvd, Suite 300, Allentown, PA 18103 (e-mail: dr.mahekshah@yahoo.co.in).3 2017 24 3 2017 96 12 e644929 10 2016 28 2 2017 1 3 2017 Copyright © 2017 the Author(s). Published by Wolters Kluwer Health, Inc.2017This is an open access article distributed under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike 4.0 License, which allows others to remix, tweak, and build upon the work non-commercially, as long as the author is credited and the new creations are licensed under the identical terms. http://creativecommons.org/licenses/by-nc-sa/4.0Supplemental Digital Content is available in the text
Abstract
Inferior vena cava filter (IVCF) placement appears to be expanding over time despite absence of clear directing evidence.
Two populations were studied. The first population included patients who received an IVCF between January 2005 and August 2013 at our community hospital center. Demographic information, indications for placement, and retrieval rate was recorded among other variables. The second population comprised of patients receiving an IVCF from 2005 to 2012 according to the Nationwide Inpatient Sample (NIS) using ICD-9CM coding. Patients were divided into 2 groups based on the year of admission for comparison, that is, first group from 2005 to 2008 and the second from 2009 to 2012. In addition, we analyzed annual trends in filter placement, acute venothromboembolic events (VTE) and several underlying comorbidities within this population.
At our center, 802 IVCFs were placed (55.2% retrievable); 34% for absolute, 61% for relative, and 5% for prophylactic indications. Major bleeding (27.5%), minor self-limited bleeding (13.7%), and fall history (11.2%) were the commonest indications. Periprocedural complication rate was 0.7%, and filter retrieval rate was 7%. The NIS population (811,487 filters) saw a decline in IVCF placement after year 2009, following an initial uptrend (Ptrend < 0.01). IVCF use among patients with neither acute VTE nor bleeding among prior VTE saw a 3-fold absolute reduction from 2005 to 2012 (33,075–11,655; Ptrend < 0.01). Patients from 2009 to 2012 were more likely to be male and had higher rates of acute VTE, thrombolytic use, cancer, bleeding, hypotension, acute cardiorespiratory failure, shock, prior falls, blood product transfusion, hospital mortality including higher Charlson comorbidity scores. The patients were younger, had shorter length of stay, and were less likely to be associated with strokes including hemorrhagic or require ventilator support. Prior falls (adjusted odds ratio—aOR 2.8), thrombolytic use (aOR 1.76), and shock (aOR 1.45) were most predictive of IVCF placement between 2009 and 2012 on regression analysis.
Recent trends suggest that a higher proportion of patients receive temporary IVCF, for predominantly relative indications. Nationally, the number of filters being placed is decreasing, especially among those who did not experience acute VTE or bleeding events. Prior falls, thrombolytic therapy, and shock were most predictive of IVCF placement in latter half of the study period.
Keywords
appropriatecontraindicationinappropriateindicationIVC filterNationwide Inpatient SampleretrievaltrendsOPEN-ACCESSTRUE
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1 Introduction
Venous thromboembolism (VTE) is a significant cause of morbidity and mortality in the United States with an average annual incidence of 1 to 2 cases per 1000 person years.[1] For patients with VTE, the mainstay of treatment is anticoagulation therapy. Inferior vena cava filters (IVCF), initially introduced in the 1960s have continued to evolve since, and may be considered when anticoagulation is contraindicated or fails. While all major guidelines agree on these indications, some indications are more controversial (i.e., patients with VTE and limited cardiopulmonary reserve, questionable compliance, or recurrent falls).[2–4] Additionally, they are increasingly utilized for prophylaxis in the absence of VTE despite the lack of convincing evidence.[5] Though filters are usually placed via minimally invasive procedures, there is clear evidence for filter-related complications even several years after placement.[6] There is a great deal of inconsistency in the recommendations by different societies with relative liberalization of filter use by the Society of Interventional Radiology compared to the American College of Chest Physicians (ACCP).[3,4,7]
IVCFs have been in use since their initial approval through the FDA's 501K clearance protocol despite the presence of minimal human or animal data. According to a National Discharge Survey (1979–1999) and a Medicare survey (1999–2008) rates of IVCF placement have markedly increased in the last 2 decades.[8,9] This is likely a combination of an increasing number of providers capable of IVCF insertion, an aging population with contraindication to anticoagulation, introduction of retrievable filters, and newer applications for filter placement.[10]
The expanding indications and utility of IVCFs prompted us to examine IVCF use including that of retrievable filters during a 9-year period at our institution. In addition, we decided to assess national trends in IVCF placement using the Nationwide Inpatient Sample (NIS).
2 Subjects and methods
Two distinct populations who received IVCF were studied and were analyzed separately as below. The Institutional Review Board at Einstein Medical Center in Philadelphia approved the study.
2.1 Study population A
We reviewed the electronic medical records of all patients who had an IVCF placed at the institute from January 1, 2005 to August 31, 2013. All filters were placed by the interventional radiology team. Patients under the age of 18 years and pregnant patients were excluded. The requirement for permission was waived because of the retrospective nature of the study and the minimal risk posed to the patients. Information regarding the acuity of a VTE event (deep vein thrombosis—DVT and/or pulmonary embolism—PE) and anticoagulation use was collected. Demographic information (age, sex, gender) and clinical data (presence of hypertension, diabetes, hyperlipidemia, end-stage renal disease, end-stage liver disease, connective tissue disorders, and malignancy) was recorded.
Information regarding the indication for IVCF use, contraindications to use of anticoagulation, and complications arising due to filter placement during the index admission were reviewed. We defined the indications for IVCF use as follows:1. Absolute indication: Acute VTE while therapeutic on anticoagulation or in the presence of absolute contraindication to anticoagulation (recent neurosurgical procedure, major active or recent bleeding, coagulopathy).
2. Relative indication: Patient with acute or prior VTE considered at higher risk for either bleeding complications from anticoagulation or hemodynamic instability (transient bleeding, recurrent falls, multiple comorbidities, extensive PE, questionable compliance, central nervous system neoplasms, perioperative DVT, active cancer with potential for bleeding, poor cardiovascular reserve, ileocaval DVT, DVT with free floating thrombus).
3. Prophylactic: IVCFs were placed in the absence of current or prior VTE.
This classification system is in concordance with published guidelines.[2–4] Patients with more than one indication were categorized by the most clinically relevant indication. In-hospital mortality was recorded if it occurred during the same hospitalization as filter placement. Our institutional follow-up protocol includes written instructions upon discharge and an additional letter mailed to home within 30 days encouraging patients to follow up with their care providers and reassess need for filter including possible retrieval. The number of IVCF removal procedures during study period was recorded. Informed consent was not obtained from patients due to the retrospective nature of data collection and analysis.
2.2 Study population B
Data from the 2005 to 2012 Agency for Healthcare Research and Quality (AHRQ) Health Care Utilization Project Nationwide Inpatient Sample (NIS) was used. Patients aged 16 years and older who received an IVCF (ICD-9CM coding, procedure code 38.7) were included. Those who were transferred out during stay to another hospital and had missing information were excluded. The NIS is part of the Healthcare Cost and Utilization Project (HCUP), sponsored by the AHRQ. The NIS is the largest publicly available all-payer inpatient care database in the United States. A comprehensive synopsis on NIS data is available at http://www.hcup-us.ahrq.gov. Death was defined in the NIS as in-hospital mortality. Different comorbidities were identified by using ICD-9-CM diagnoses and diagnosis-related group (see Appendix). We defined severity of comorbid conditions using Deyo modification of Charlson comorbidity index. This index contains 17 comorbid conditions with differential weights. The score ranges from 0 to 33, with higher scores corresponding to greater burden of comorbid diseases. Trends were analyzed from 2005 to 2012 for the rates of filter placement, baseline demographics, acute VTE events, clinical characteristics, in-hospital mortality and associated comorbidities including calculated Charlson comorbidity index. Two groups (4 years each) based on year of IVC filter placement: 2005 to 2008 and 2009 to 2012 were created for the purpose of analysis and comparison of the study variables.
Demographic, procedure-related data and all relevant clinical information in the Study population A was summarized using descriptive statistics and percentages. Cases from the NIS were weighted in order to approximate national averages and trends. Continuous data were expressed as mean ± 1 standard deviation and categorical data as frequencies or percentages. The Student t test was used for continuous variables, and Fisher exact or Chi-square test for categorical variables. Trend analyses were performed using the Mantel–Haenszel test of trend and analysis of variance test for categorical and continuous variables respectively. Levene test of homogeneity was performed following the analysis of variance test for continuous variables before to deciding appropriate test for significance. A multivariable hierarchical mixed effect logistic regression model was created to assess which variables among age, sex, Caucasian race, elective admission, length of stay, Charlson comorbidity index, hypotension, stroke or transient ischemic attack, acute cardiorespiratory failure, ventilator use, acute DVT, acute PE, coagulation disorder, bleeding event, cancer, blood product transfusion, prior falls and thrombolytic use were likely to predict placement of an IVCF between 2009 to 2012 compared to the first half of study. P-value <0.05 was considered significant. All analyses were performed using the IBM SPSS Statistics for Windows, Version 20.0 (Armonk, NY) statistics software.
3 Results
3.1 Study population A
3.1.1 Baseline characteristics
Between January 2005 and August 2013, a total of 802 IVCFs were placed in 802 patients. Table 1 represents the characteristics of patients who received an IVCF. Females comprised 57% of all filter recipients and more than a quarter of all patients had underlying hypertension or diabetes mellitus. An active or history of malignancy was present in 35% of patients. More than 25% of the filters were placed in patients with a bleeding history. A total of 176 patients (22%) were already on anticoagulation preceding hospital encounter with 70.4% of them being either therapeutic or supratherapeutic on anticoagulation. An acute thromboembolic event was diagnosed in 602 (75%) patients; whereas 160 (20%) patients had a prior VTE and 40 (5%) patients had no current or past VTE.
Table 1 Baseline characteristics of the study population at our institute.
3.1.2 Filter type and complications
Among the 802 filters, 443 (55%) were temporary and the rest were permanent. Figure 1 illustrates the increasing trend in the utility of temporary filters over our study period (Ptrend < 0.05). A total of 785 (97.8%) filters were placed in the inpatient setting while 17 (2.2%) were placed either as outpatients or in the emergency department. A discussion between the patient, care team, and interventional radiologist led to the choice of permanent versus temporary filter. The commonest filters placed were Option filters (23%) followed by TrapEase (21%), Vena-Tech (20%), and Bard G2 IVCFs (19%).
Figure 1 Trends in placement of temporary and permanent filters from 2005 to 2013.
The immediate complication rate for filter placement was 0.7% (6/802). All 6 complications were self-limited and included 1 case of contrast extravasation, 1 pneumothorax, 1 superficial access site hematoma, 2 retroperitoneal bleeds and an episode of transient hypotension requiring the administration of vasopressors. There were no procedure-related deaths, myocardial infarctions, or strokes. The in-hospital mortality for patients requiring IVCFs was high at 8.7%.
3.1.3 Indications for IVCF placement
Table 2 shows a breakdown of the listed indications for IVCF placement as described above. All patients within the absolute and relative indication groups had need for continued anticoagulation in the setting of either acute, acute on chronic, or chronic VTE. Absolute indications necessitated filter placement in 34% of the cases, most commonly for contraindications to anticoagulation (221/269). Among these patients, 175/221 (79.1%) had an acute VTE in addition to bleeding. Additionally, 48/269 (17.8%) of the patients received the IVC because of recurrent VTE on failed anticoagulation.
Table 2 Documented indications for IVC filter placement.
Figure 2 represents how relative indications outnumbered absolute indications for IVCF placement during study period. A total of 493 filters (61%) were placed for relative indications. Minor self-limited bleeding (110/493, 22%), history of falls (90/493, 18%), and dementia or multiple comorbidities (73/493, 15%) represented more than half of the relative indications for IVCF placement. Fifty-seven patients received an IVCF in the setting of a massive pulmonary embolus, while 21 received a filter in the setting of poor cardiorespiratory reserve. Forty filters (5%) were placed prophylactically in high risk patients in the absence of documented VTE. At the time of filter placement, 252 patients (31.4%) were receiving concomitant therapeutic anticoagulation and 210 (26.2%) patients were taking anticoagulants at the time of discharge. A total of 48 (5.9%) patients received thrombolysis and 38 (4.7%) underwent thrombectomy. Filter retrieval was attempted in 31 (3.8%) patients and was successful in 29 of them.
Figure 2 Annual trends in indications for IVC filter placement from 2005 to 2013.
3.2 Study population B
3.2.1 Trends in IVCF placement and associated variables
A total of 811,487 IVCF placements were studied between 2005 and 2012. IVCF placement increased from 103,843 in the year 2005 to 131,843 by year 2009, following which it steadily declined to less than half of the peak by the year of 2012 (n = 63,445) as seen in Fig. 3 (Ptrend < 0.01). Figure 3 represents a similar pattern in IVCF placement among patients with neither acute VTE nor prior VTE with bleeding during current hospitalization, showing a roughly 3-fold decline between 2005 and 2012 (Ptrend < 0.01).
Figure 3 Trend in placement of IVC filters between 2005 and 2012 based on Nationwide Inpatient Sample.
Figure 4 A–F represents the annual variations and trends in patient demographics, baseline characteristics, comorbidities including in-hospital mortality, cost of stay, and length of stay during the study period among patients who received an IVCF. It can be noted that there was an overall uptrend favoring IVCF placement with time in patients who were younger, male, Caucasian, and had an increasing association with clinical variables such as acute VTE (both PE and DVT), prior VTE, bleeding events, cancer, hypotension, shock, thrombolytic use, and blood product transfusion. The in-hospital mortality showed a relative 23% increase by the year 2012 (9.6%) compared to the year 2005 (7.8%). On the other hand, proportion of patients with a stroke or transient ischemic attack, those needing ventilator support and length of hospital stay saw a downtrend during study period. Ptrend for all represented variable trends was <0.01.
Figure 4 (A–F) Trends in patient characteristics, comorbidities, admission-related variables, and disease-associated complications including in-hospital mortality among patients who received an IVC filter between 2005 and 2012.
3.2.2 2005–2008 versus 2009–2012
Patients were categorized into 2 groups, 4 years each and comparisons were made between the first and second half of the study duration to examine the changes in practice across several characteristics. The latter 4 years already saw a 27.5% decline in the total number of filters placed. Table 3 represents the differences between the 2 groups.
Table 3 Baseline characteristics between patients who received an IVC filter within the Nationwide Inpatient Sample, grouped according to year.
Patients in the 2009- to 2012-year group were younger, more likely to be Caucasian or male with higher hospital mortality rates. The total cost of stay was higher despite shorter length of stay. These patients had higher Charlson comorbidity scores, prior falls and greater rates of shock and acute cardiorespiratory failure. Patients in the latter study half had higher rates of acute PE or DVT, thrombolytic use, hypotension, cancer, bleeding events, and transfusion of blood products. This group also had a higher proportion of patients with neither acute VTE nor bleeding in presence of prior VTE (21.6% vs 28.3%; P < 0.001). Patients in the first half of the study experienced relatively higher stroke rates including hemorrhagic strokes, and ventilator use.
A regression analysis revealed that prior falls (adjusted odds ratio (aOR) 2.8, 95% confidence interval (CI) 2.67–2.93; P < 0.001)), thrombolytic use (aOR 1.76, 95% CI: 1.72–1.81; P < 0.001), bleeding event (aOR 1.38, 95% CI: 1.37–1.40; P < 0.001), shock (aOR 1.45, 95% CI: 1.42–1.48; P < 0.001), hypotension (aOR 1.39, 95% CI: 1.36–1.42; P < 0.001), Caucasian race (aOR 1.40, 95% CI: 1.38–1.41; P < 0.001), acute cardiorespiratory failure (aOR 1.36, 95% CI: 1.34–1.38; P < 0.001), acute DVT (aOR 1.22, 95% CI: 1.21–1.23; P < 0.001), and acute PE (aOR 1.19, 95% CI: 1.18–1.20; P < 0.001) were the most prominent independent predictors of a higher likelihood for IVCF placement between 2009 and 2012.
4 Discussion
Acute PE remains the most serious clinical presentation of VTE, and is a major cause of morbidity and mortality accounting for ≥300,000 deaths each year in the United States. Prompt treatment is recommended in affected patients with the goal to halt progression of disease, and reduce risk for recurrent episodes of thromboembolism and/or death.[3,11–14] The primary aim of filter insertion is prevention of fatal PE. There are currently no randomized trials to evaluate the benefit of IVCFs over anticoagulation in patients with absolute or relative contraindications to anticoagulation as these patients were excluded from prior randomized trials.[15,16]
Our study aimed to investigate indications for IVCF placement, and analyze the trends in type of filter use over a 9-year period at an urban academic medical center. We found that a majority of the filters were placed for relative indications, and there was a trend toward more temporary filter placement with time between years 2005 and 2013. There is overall agreement amongst societies for the insertion of IVCFs when it comes to patients with absolute contraindication to anticoagulation or complications of anticoagulation, the former encompassing active bleeding, recent surgery, coagulopathy and recent neurosurgical procedure or intracranial bleeding.[2–4,14] In older studies, absolute indications guided IVCF placement in as much as 60% of the cases, compared to 30% at our institute.[17,18] High rates of filter placement for prophylactic or relative indications have been reported in previous studies from the United States, in hospitals with busy trauma services.[19]
Forty-eight patients received an IVCF because of recurrent VTE despite optimal anticoagulation, representing slightly more than 5% of our cohort. In a previous study, failure of anticoagulation was noted to be the indication for 3% to 5% of the filters placed.[19] Although traditionally considered an indication for an IVCF, we like to emphasize that the recent Chest guidelines actually recommend modification of the anticoagulation regimen over IVCF placement in such individuals.[20] We may see the prevalence of this indication reduce as more practitioners adapt the newest guidelines.
Relative indications were linked to the placement in almost 2nd/3rd of the filters at our institute, results that are in line with prior published data indicating a rise in placement of filters for relative indications.[21] These patients were likely to be elderly, high fall risk, noncompliant, with active malignancies and considered at a high risk for bleeding complications with anticoagulation. Within the same category, we included patients with large PEs and poor cardiopulmonary reserve. Interestingly, according to another study patients that experienced a significant increase in filter placement were the elderly and those at risk for falls.[17] According to our analysis, presence of old age with comorbidities and risk of falls contributed to more than 1 out of all 5 filters placed. It is an alarming statistic given the paucity of supportive data for use in this patient population.
Previously published national data suggest a possible survival benefit to using IVCFs in unstable patients and those receiving thrombolytic therapy.[22,23] Fewer than 6% of the patients in both our study populations received thrombolytic therapy. With increasing discordance amongst societies on these relative indications, physician compliance in practice with the guidelines has been found to be expectedly poor.[7]
Prior studies have demonstrated a significant increase in the number of IVCFs placed as prophylaxis, mostly in patients with major trauma.[8,24] This trend was thought to have at least been partially driven by studies demonstrating a reduction in PE after IVCF placement in such patients.[24] However, these results were not confirmed in other studies and consequently the 2012 ACCP guidelines recommend against the prophylactic use of IVCFs.[3] In our study, only 5% of the IVCFs were placed prophylactically, most commonly in trauma patients or patients undergoing bariatric or neurosurgical procedures. Recent data questions the cost-effectiveness of prophylactic IVCFs compared to therapeutic filters.[31] Meltzer et al[32] found a higher IVCF use in states with higher medico-legally litigious environments. In this era of cost-conscious care emphasis needs to be placed on appropriate patient stratification to eliminate unnecessary interventions.
According to our analysis, 443 of the filters were designed for retrieval but only 29 (7%) were successfully removed. Although temporary IVCFs are becoming increasingly popular, their timely removal remains a significant challenge. IVCF retrieval rates have traditionally been below 50%, even in large academic centers. For example, in a study of mostly trauma patients who received IVCF done by Sarosiek et al,[19] only 8.5% (58/679) of retrievable filters were actually removed. The highest retrieval rates have been reported in a study from the UK where an attempt to remove the IVCF was performed in 40% of patients and was successful in 32% of them.[18] These numbers indicate that the majority of optional filters are not being actively removed, thereby increasing the risk of long-term complications such as DVT. In a recent analysis by Siracuse et al, factors associated with IVCF nonretrieval were age >80 years, current malignancy, postfilter anticoagulation and history of a DVT/PE.[25] In our study, the low retrieval rate may also be attributed to the lack of a standardized follow up protocol, socioeconomic barriers, and poor health literacy. This again highlights the utility of establishing IVCF clinics and possible allocation of resources to pursue a more aggressive approach when it comes to follow ups and ensuring timely removal. The Food and Drug Administration (FDA) issued a statement in 2010 urging physicians to consider removing IVCFs as soon as protection was no longer needed.[26]
Of patients with VTE's who had filters placed, 252 patient were receiving anticoagulation at the same time and eventually 210 were discharged on anticoagulant medication. This was similar to the rates reported in an analysis from Boston Medical Center.[19] Once the risk of bleeding is assessed to be low, such that conventional anticoagulation can be started, the general recommendation is that the filter be removed.[3] Hence, we can infer that many of the patients may have qualified for filter removal even prior to hospital discharge. We agree that the tendency to discharge patients with IVCFs on anticoagulation could be influenced by the number of permanent IVCFs being placed. However, we hypothesize that among the most likely contributors are an increased reimbursement rates when filters are retrieved in an outpatient setting and an under appreciation of the potential harms of leaving filters in place for extended periods.[19] We acknowledge that this practice exposes the patients to unnecessary risk while providing no benefit in terms of PE recurrence prevention, as clearly demonstrated in the PREPIC 2 trial.[27]
Complications of IVCF placement include access site hematoma, IVC thrombosis, air embolism, pneumothorax, filter migration or fracture and IVC perforation.[28] Some of these complications may be evident early; others are asymptomatic or can be seen as a late event. Hadjuk et al, demonstrated filter thrombosis in up to 30% of patients receiving this device, however, the vast majority of these events were completely asymptomatic.[29] The nature of our study allowed only for the detection of immediate symptomatic complications. In our cohort, their incidence was 0.7%, which is significantly lower than the prior reported rates between 4 to 15.[30] Nationally, the in-hospital mortality rates were significantly high (8.7%) among patients receiving IVCFs. This probably reflects the underlying severity of illness and high prevalence of comorbidities among these patients.
Kuy et al[33] analyzed the NIS data from 2000 to 2009 and found a 234% increase in IVCF placement over the decade. They also found that roughly 84.7% of the patients had a PE or DVT. These findings were similar to a 21-year study on IVCF trends reported by Stein et al.[8] In another analysis of the NIS, on one hand IVCF cases between increased from 2001 to 2008, the mortality rate saw a decline during the same study period. Our study analyzed patients from 2005 to 2012 and found that the number of IVCF placements experienced a downward trend following the year 2009 after the initial uptrend, whereas the in-hospital mortality saw an increase over the entire study period, that was most marked from 2009 to 2010. The rate of IVCF placement although lower toward the latter half of the study, was more likely in patients with acute or prior VTE, bleeding events, hypotension, shock, cardiorespiratory system compromise and among those requiring thrombolytic use. These patients had higher rates of in-hospital mortality rates and higher Charlson comorbidity scores reflecting a higher risk category of patients compared to former years. These recent changes in practice may be attributable to increasing awareness among caretakers on the lack of evidence for IVCF placement in most cases and also the FDA advisory warning of 2010. In addition, IVC filter-related late complications and litigation surrounding inappropriate placement, lack of retrieval, filter-related complications, lower reimbursement for inpatient filter placement may have all contributed to changing practice. The PREPIC 2 randomized study published in 2015 showed no benefit of IVCF placement over anticoagulation in high risk PE patients, however other observational studies since 2012 continue to show variable findings suggesting benefit in some.[22,23,27] Hence, it may be challenging to predict future trends in IVCF placement but in our assessment, are unlikely to trend up significantly.
Being retrospective in nature, the study suffers from the limitations inherent to such a study design and presence of confounding and unmeasured variables. The study is also subject to biases related to such data as accuracy of the documented records and ICD coding for procedure and diagnosis in the case of the NIS database. The use of multiple different types of filter over 9 years at our institute makes generalization of these findings challenging with regards to efficacy and complication rates, since these properties may be affected by the device type. In addition, the NIS sample includes only inpatients and hence is not representative of outpatient practice.
Our findings mainly suggest that a majority of filters were placed for relative indications with an increasing proportion of the filters over time being temporary. IVCFs for DVT/PE prophylaxis were uncommon at our institute. Periprocedural complications around filter placement were low with an overall low retrieval rate at our center. There was a high use of concomitant anticoagulation among patients. The national trends in IVCF placement have declined following 2009 and a relatively sicker proportion of patients with higher mortality rate and comorbidities were more likely to receive them as time progressed. In addition, the number of filters being placed among patients with neither acute VTE nor bleeding during current hospitalization in patient with prior VTE has seen a significant decline.
There is a need for dedicated prospective studies particularly in the groups of patients who require filters for relative or prophylactic indications. We also acknowledge that such an endeavor can be challenging due to the vast array of indications, ethical challenges and significant heterogeneity among the patients who receive filters. In the meantime, a relatively stringent approach for patient selection, filter placement, and prompt retrieval must be advocated.
5 Conclusions
The recent trend is toward more temporary IVCF placement for relative indications. Nationally, the number of filters being placed is decreasing, most pronounced among those without acute VTE or bleeding. Recent trends indicate that prior falls, thrombolytic use and bleeding complications were most predictive for IVCF placement among patients.
Supplementary Material
Supplemental Digital Content
Abbreviations: ACCP = American College of Chest Physicians, AHRQ = Agency for Healthcare Research and Quality, aOR = adjusted odds ratio, CI = confidence interval, DVT = deep vein thrombosis, FDA = Food and Drug Administration, HCUP = Healthcare Cost and Utilization Project, IVCF = inferior vena caval filter, NIS = Nationwide Inpatient Sample, PE = pulmonary embolism, PREPIC = Prevention of Recurrent Pulmonary Embolism by Vena Cava Interruption, VTE = venous thromboembolism.
TA and SP contributed equally to this study.
Funding sources: No study specific funding was used to support this work. The authors are solely responsible for the study design, conduct and analyses, drafting and editing of the manuscript and its final contents. All authors had access to the data and a role in writing the manuscript.
The authors have no conflicts of interest to disclose.
Supplemental Digital Content is available for this article.
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Medicine (Baltimore)Medicine (Baltimore)MEDIMedicine0025-79741536-5964Wolters Kluwer Health 28328858MD-D-16-0766510.1097/MD.0000000000006452064524500Research ArticleClinical Case ReportRetroperitoneal and intrahepatic metastasis from primary clear cell carcinoma of the liver A case report and review of the literatureXiong Junjie MDaHe Du MDbHu Weiming MDaLiu Xubao MD, PhDa∗Qi. Peng a Department of Pancreatic Surgeryb Department of Pathology, West China Hospital, Sichuan University, Chengdu, Sichuan, China.∗ Correspondence: Xubao Liu, Department of Pancreatic Surgery, West China Hospital, Sichuan University, Chengdu, Sichuan, China. (e-mail: liuxb2011@126.com)3 2017 24 3 2017 96 12 e645222 12 2016 5 2 2017 23 2 2017 Copyright © 2017 the Author(s). Published by Wolters Kluwer Health, Inc.2017This is an open access article distributed under the terms of the Creative Commons Attribution-Non Commercial-No Derivatives License 4.0 (CCBY-NC-ND), where it is permissible to download and share the work provided it is properly cited. The work cannot be changed in any way or used commercially without permission from the journal. http://creativecommons.org/licenses/by-nc-nd/4.0Abstract
Background:
Hepatocellular carcinoma (HCC) is a major cause of cancer-related mortality worldwide and the incidence is increasing as a result of growing hepatitis B and C virus infections. Primary clear cell carcinoma of the liver (PCCCL) is a rare subgroup of primary HCC, which has low metastatic potential and infrequently reported in literature. Retroperitoneal and intrahepatic metastasis of PCCCL has not been reported previously.
Case Summary:
Here, we present a 55-year-old male with retroperitoneal and intrahepatic metastasis of PCCCL who is managed with surgical method and transcatheter arterial chemoembolization (TACE) at our institution. When the patient is followed up in 16 months after surgery and TACE, he is alive without any extrahepatic metastasis and abnomal liver function.
Conclusion:
We concluded that surgical resection of retroperitoneal metastasis and TACE of the intrahepatic tumors provided an appropriate strategy for the patient with unresectable PCCCL accompanied with extra-hepatic metastasis.
Keywords
clear cell carcinomahepatocellular carcinomaintrahepatic metastasisretroperitoneal metastasistranscatheter arterial chemoembolizationOPEN-ACCESSTRUE
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1 Introduction
Hepatocellular carcinoma (HCC) is the fifth most common cancer and the third leading cause of cancer-related deaths worldwide. About 80% cases are reported from Asian countries, accounted for by the high prevalence of Hepatitis B and C infections in this region.[1] Extrahepatic metastasis of HCC at the time of initial diagnosis, even if the primary lesion is locally advanced, is however a rare phenomena.[2] Primary clear cell carcinoma of the liver (PCCCL) is a rare type of HCC, pathologically characterized by diffuse clear cells of the tumor, showing a clear cytoplasm that does not stain with hematoxylin-eosin.[3] Histologically, the tumor cells are moderately differentiated with low metastatic potential and diagnosis is usually made by correlation of histopathology, tumor markers, and immunohistochemistry. Treatment and prognosis of PCCCL with distal organ metastasis is infrequently reported in literature. We present an interesting case of PCCCL associated with retroperitoneal and intrahepatic metastasis in a hepatitis B virus (HBV)-related cirrhotic patient with surgical resection and transcatheter arterial chemoembolization (TACE) management. To the best of our knowledge, this is the first report of such a case in the worldwide.
2 Case presentation
This study was approved by the Institutional Ethic Committee of West China Hospital, Sichuan University. Written informed consent was obtained from this patient. The patient was a 55-year-old male who presented with a 1-month history of persistent right upper quadrant abdominal pain referred to the right shoulder, associated with episodes of chills and fever along with 5 kg weight loss and anorexia. There were no significant medical co-morbidities, other than positive Hep B status, or medication history and there was a 30 pack year history of smoking with moderate alcohol intake. On examination, the patient was hemodynamically stable with no evidence of jaundice and had some tenderness in the right upper quadrant.
Investigations revealed a white blood cell count of 11,730/mm3 with necrophilia (87%). Liver function tests (LFTs) were normal other than direct bilirubin, 9.8 μmol/L (normal range, <8.8 μmol/L); tumor markers showed elevated alpha-fetoprotein (AFP) 175.5 ng/mL (normal range, <8 ng/mL) and carbohydrate antigen 19–9(CA19–9) 30.44U/mL (normal range, <22U/mL). Carcinoembryonic antigen (CEA) and carbohydrate antigen-125 (CA-125) were within normal range. Serum hepatitis B surface antigen (HBsAg), e antibody (HBeAb), and core antibody (HBcAb) tests were positive, whereas serum hepatitis C antibody (HCVAb) was negative. Chest x-ray was unremarkable.
Abdominal CT showed a large, high-density retroperitoneal mass measuring 5.2 × 4.9 cm with complete capsule formation, which had no clear demarcation with the duodenum and the head of the pancreas. There was increased enhancement in the arterial and portal phase of the scan (Fig. 1A). Abdominal MRI revealed that the mass had a well-defined low-intensity T1-weighted image (Fig. 1B). Furthermore, there were many low-density nobes varying sizes throughout the liver and multiple enlarged lymph nodes in the hepatogastric ligaments and para-aortic region.
Figure 1 (A) Abdominal contrast CT scan showed the retroperitoneal mass (black arrow) and the multiple intrahepatic lesions (white arrow). (B) Axial T1-weighted MRI scan showing the retroperitoneal mass with low-intensity image (black arrow) and multiple intrahepatic lesions (white arrow). CT = computed tomography, MRI = magnetic resonance imaging.
A provisional diagnosis of pancreatic head or duodenal tumor with liver metastasis was made. The patient underwent an exploratory laparotomy and was found to have a gray–white, smoothly encapsulated retroperitoneal solid mass with a necrotic part in the center adherent to the duodenum and right colon with palpable lymph nodes in the lesser omentum. The liver had many low-density mostly about 2 to 3 mm, the largest about 2.6 cm in size. Given the extent of disease, a decision to perform cytoreductive surgery was made, since wide range hepatectomy was not possible. Intraoperative frozen histopathological examination indicated that the tumor in liver was HCC, but the reoperitoneal mass was of unclear origin and pancreatic endocrine tumor could not be excluded. Therefore, the retroperitoneal mass was completely excised and TACE were completed for the liver tumors. There were no intra- or postoperative complications and the patient was discharged 5 days after surgery. Interestingly, the final histopathology of the retroperitoneal mass was extra-hepatic metastasis of PCCCL. Hematoxylin and eosin (H&E) showed that an HCC with clear cell variant in the liver and retroperitoneal mass (Fig. 2A and B). The retroperitoneal mass had approximately 60% clear cells. Immunohistochemical staining of cells from the retroperitoneal mass showed that the tumor cells were positive for Hep1(Fig. 2C), epithelial membrane antigen (EMA), and Ki67 (about 40%), but negative for AFP, chromogranin A(CgA), Syn, CD56, Inhibin, renal cell carcinoma antigen (RCC) and melanoma antigen recognized by T cells 1(MART-1). These results supported a diagnosis of PCCCL with retroperitoneal and intrahepatic metastasis. Since TACE is safe and effective therapy for intrahepatic multiple tumors in advanced stage. On 16 months follow-up, the patient was asymptomatic with normal LFTs and no extrahepatic metastasis.
Figure 2 (A) Cells of liver tumor with clear cytoplasm visible on a background of cirrhosis (HE, ×150). (B) Cells from retroperitoneal tumor, mainly diffuse clear cells (60%) with a clear cytoplasm that did not stain with hematoxylin and eosin (HE, ×300). (C) Immunohistochemistry of the retroperitoneal tumor positive for Hep1 confirmed the tumor as hepatocellular carcinoma (×300). HE = hematoxylin-eosin.
3 Discussion
PCCCL is a rare entity accounting for 7.5% to 12.5% of all liver cancer cases and is infrequently reported in literature. [4] Liver cirrhosis is known to be an important risk factor for HCC and is strongly associated with PCCCL and focal PCCCL compared to non-PCCCL liver cancers.[5] It is accepted that cytoplasmic accumulation of lipid plays a major role in the development of the clear cytoplasm in PCCCL. PCCCL cells also have significantly fewer cytoplasmic organelles than non-PCCCL cells. In this case, we used the diagnostic criteria from pathologists in China to diagnose PCCCL, which has a cut off of >50% clear cells.[6] In the present case, the proportion of clear cells was approximately 60%.
PCCCL poses a diagnostic dilemma without the aid of the immunohistochemical staining. If only small tissue sections are available, an accurate diagnosis may not be possible histologically and in ambiguous cases it may be difficult to distinguish PCCCL from metastatic clear cell carcinomas originating in the adrenals, kidneys, ovaries, lung, and other organs. Cytokeratin profiling, and evidence of immunoreactivity for AFP and EMA, is probably a helpful criterion in making the differential diagnosis even in clear cell carcinomas of the liver. In our case, the diagnosis of PCCCL was further supported by raised serum AFP levels, and immunohistochemistry revealed Hep1 positivity, although EMA and AFP were negative.
Generally, PCCCL tumors display a low-grade malignancy, are encapsulated, and surgical resection is the most promising therapeutic treatment. The overall prognosis of PCCCL is still unclear as there are some reports suggesting that the outcome of patients with PCCCL is better than those with other types of HCC[7] and there are other data indicating that the prognosis of these patients is similar to its common type counterparts and may be even worse.[8,9] To date, there is no consensus on the treatment strategy for extrahepatic and intrahepatic metastasis of the PCCCL. The role of postoperative adjuvant chemotherapy in PCCCL is also controversial. We reviewed literature about retroperitoneal and intrahepatic metastatic PCCCL, only Kobayashi et al[10] reported 1 patient with retroperitoneal metastasis and intrahepatic recurrence of HCC. However, our case was different from that report, because the retroperitoneal metastasis of HCC happened after the liver resection and the exact subtype of pathological was not known. Similary, that patient was given the TACE for intrahepatic recurrent tumors and he was alive in his first year after surgery without any extrahepatic metastasis. For our case, on 16 months follow-up, the patient was also without extrahepatic metastasis and LFTs was normal.
However, some limitations of this report should be recognized. First, this is just a case report which restricted the promotion for our treatment method; therefore, a bigger patient population is needed in further research; Second, the long-term follow-up should be given to the patient for confirming this therapeutic effect; Third, some factors influence the outcome of the management, such as the preoperative serum AFP level, HBV infection and tumor size and proportion of clear cells. However, this report is just a case, so we cannot analyze the above factors.
In conclusion, we report a unique case of retroperitoneal and intrahepatic metastasis of PCCCL. In clinical practice, although there is presently no consensus on the optimum treatment strategy in this condition, therapeutic approaches to control intrahepatic tumors are important in improving patient survival. Our experience suggests that surgical resection of extrahepatic metastases and TACE for hepatic tumors provided an appropriate strategy for the patient with unresectable PCCCL accompanied with extra-hepatic metastasis and can be considered by other hepatopancreatobiliary teams.
Abbreviations: AFP = alpha-fetoprotein, CA-125 = carbohydrate antigen-125, CA19–9 = carbohydrate antigen 19–9, CEA = carcinoembryonic antigen, CgA = chromogranin A, EMA = epithelial membrane antigen, HBV = hepatitis B virus, HCC = hepatocellular carcinoma, LFTs = liver function tests, MART-1 = melanoma antigen recognized by T cells 1, PCCCL = primary clear cell carcinoma of the liver, RCC = renal cell carcinoma, TACE = transcatheter arterial chemoembolization.
Authorship: XL designed the research; JX and DH collected research data and wrote the manuscript; WH and XL revised the manuscript. XL reviewed the literature. All authors read and approved the final manuscript.
The authors have no funding and conflicts of interest to disclose.
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Medicine (Baltimore)Medicine (Baltimore)MEDIMedicine0025-79741536-5964Wolters Kluwer Health 28328860MD-D-17-0075210.1097/MD.0000000000006454064543300Research ArticleSystematic Review and Meta-AnalysisVentilation during cardiopulmonary bypass for prevention of respiratory insufficiency A meta-analysis of randomized controlled trialsChi Dongmei MDChen Chan MD, PhDShi Yu MDWang Wanyu MDMa Ye MDZhou Ronghua MDYu Hai MD∗Liu Bin MD∗Hanaoka. Kazuo Department of Anesthesiology, West China Hospital, Sichuan University, Chengdu, Sichuan, China.∗ Correspondence: Hai Yu, Department of Anesthesiology, West China Hospital, Sichuan University, Chengdu, China (e-mail: yuhaishan117@yahoo.com); Bin Liu, Department of Anesthesiology, West China Hospital, Sichuan University, Chengdu, China (e-mail: liubinhx@foxmail.com).3 2017 24 3 2017 96 12 e64549 2 2017 24 2 2017 24 2 2017 Copyright © 2017 the Author(s). Published by Wolters Kluwer Health, Inc.2017This is an open access article distributed under the terms of the Creative Commons Attribution-Non Commercial-No Derivatives License 4.0 (CCBY-NC-ND), where it is permissible to download and share the work provided it is properly cited. The work cannot be changed in any way or used commercially without permission from the journal. http://creativecommons.org/licenses/by-nc-nd/4.0Supplemental Digital Content is available in the text
Abstract
Background:
Cardiopulmonary bypass (CPB) is necessary for most cardiac surgery, which may lead to postoperative lung injury. The objective of this paper is to systematically evaluate whether ventilation during CPB would benefit patients undergoing cardiac surgery.
Methods:
We searched randomized controlled trials (RCTs) through PubMed, Embase, and Cochrane Library from inception to October 2016. Eligible studies compared clinical outcomes of ventilation versus nonventilation during CPB in patients undergoing cardiac surgery. The primary outcome includes oxygenation index (PaO2/FiO2 ratio) or alveolar to arterial oxygen tension difference (AaDO2) immediately after weaning from bypass. The secondary outcomes include postoperative pulmonary complications (PPCs), shunt fraction (Qs/Qt), hospital stay, and AaDO2 4 hours after CPB.
Results:
Seventeen trials with 1162 patients were included in this meta-analysis. Ventilation during CPB significantly increased post-CPB PaO2/FiO2 ratio (mean difference [MD] = 21.84; 95% confidence interval [CI] = 1.30 to 42.37; P = 0.04; I2 = 75%) and reduced post-CPB AaDO2 (MD = –50.17; 95% CI = –71.36 to –28.99; P <0.00001; I2 = 74%). Qs/Qt immediately after weaning from CPB showed a significant difference between groups (MD = –3.24; 95% CI = –4.48 to –2.01; P <0.00001; I2 = 0%). Incidence of PPCs (odds ratio [OR] = 0.79; 95% CI = 0.42 to 1.48; P = 0.46; I2 = 37%) and hospital stay (MD = 0.09; 95% CI = –23 to 0.41; P = 0.58; I2 = 37%) did not differ significantly between groups.
Conclusion:
Ventilation during CPB might improve post-CPB oxygenation and gas exchange in patients who underwent cardiac surgery. However, there is no sufficient evidence to show that ventilation during CPB could influence long-term prognosis of these patients. The beneficial effects of ventilation during CPB are requisite to be evaluated in powerful and well-designed RCTs.
Keywords
cardiopulmonary bypassmeta-analysisrespiratory insufficiencyventilationOPEN-ACCESSTRUE
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1 Introduction
Despite the improvement in perioperative management, the postoperative respiratory dysfunction is still a widely reported complication of cardiopulmonary bypass (CPB), leading to increased mortality and morbidity in cardiac surgery.[1,2] Various strategies including perioperative management of mechanical ventilation (MV), restrictive transfusion, technical modifications of CPB, and medication administration such as steroids and aprotinin have been developed to reduce impairment of pulmonary function.[3–5] Ventilation during CPB is an important element of MV management strategies and determined by anesthesiologists in the operation room. Continuous positive airway pressure (CPAP), low-volume ventilation, positive end-expiratory pressure (PEEP), and vital capacity maneuvers (VCMs) are adjustable parameters composing ventilation techniques.
So far, available researches regarding whether ventilation during CPB could improve respiratory outcomes are still controversial. Some studies found that the application of CPAP during CPB was an effective adjunct.[6,7] Gaudriot et al[8] suggested that maintaining MV during CPB could diminish immune dysfunction after surgery. However, others reported that the utilization of CPAP did not show a significant difference compared with the controls when it came to attenuating the post-CPB impairment of lung function.[9,10]
Additionally, it has been reported that the application of low tidal volume (TV)–low frequency ventilation could decrease the occurrence of CPB-related lung injury because it could decrease inflammatory reactions and some negative immune markers such as interleukin 10 and tumor necrosis factor-α (TNF-α).[11–14] But the protective function of continuous ventilation during CPB is still debatable because many studies found it is not a necessary technique for an improved respiratory outcome.[9,15] To provide the latest and more convincing evidence, we systematically reviewed the present available literature to evaluate the efficacy and safety of ventilation during CPB in patients who were scheduled to undergo cardiac surgery.
2 Methods
2.1 Search strategy
This meta-analysis was performed in accordance with PRISMA (Preferred Reporting Items for Systematic reviews and Meta-Analyses) guidelines.[16] We searched PubMed, Embase, and Cochrane Library from inception to October 2016, without a language restriction. Two reviewers conducted the searching work independently and the other 2 helped to resolve the conflicts in the process and find out the missed studies identified through other sources manually. A list of the search terms used for each electronic database is presented in Fig. S1 (Supplemental content). There is no requirement for ethical approval and patient consent as this is a meta-analysis of published studies.
2.2 Selection criteria
Study inclusion criteria were as follows: patients: adult patients (≥18 years) scheduled to undergo cardiac surgery with CPB procedure; interventions: different ventilation strategies during CPB period including either CPAP or low TV ventilation (PEEP and VCMs were not necessary factors); control: patients did not receive any type of ventilation during CPB; outcomes: the ratio of partial pressure of arterial oxygen to fraction of inspired oxygen (PaO2/FiO2 ratio), alveolar to arterial oxygen tension difference (AaDO2), shunt fraction (Qs/Qt), postoperative pulmonary complications (PPCs), and duration of hospital stay. At least 1 primary outcome, that is, either PaO2/FiO2 or AaDO2, must be reported in the eligible cites. Design: randomized controlled trials (RCTs).
Study exclusion criteria were as follows: the ventilation interventions carried out before or after the CPB period, or in the intensive care unit after surgery, or carried discontinuously (e.g., only intermittent mandatory ventilation at weaning from CPB); (the CPB procedure was not used in cardiac surgery; publication type: conference abstracts, corresponding to other trial reports, or reviews; the interventions of control group was not nonventilation during CPB; other reasons including sub-studies and small sample-sized studies (<10 patients).
2.3 Data abstraction and quality assessment
Two independent reviewers conducted data abstraction and quality assessment. Conflicts were solved by discussion. Data extracted from articles included the following: trial characteristics: author, year of publication, study design, surgery type, sample size, inclusion criteria, experimental, and control arms; overall average baseline patient characteristics: age, male percent, body mass index (BMI), length of CPB, and length of surgery; endpoints: relevant primary endpoints (PaO2/FiO2 and AaDO2) and recording time of primary endpoints; and relevant secondary endpoints: Qs/Qt, PPCs, length of hospital stay and others. The secondary outcomes were not analyzed unless the data were available in at least 3 trials.
We assessed the risk of bias of all eligible studies according to the standard of Cochrane Collaboration. The studies were assessed from the following aspects: randomized sequence generation, allocation concealment, blinding of participants and personnel, blinding of outcome assessment, incomplete outcome data, selective reporting, and other bias. In this way, the studies were assessed as low risk, high risk, and unclear risk.[17]
2.4 Quality of evidence
GRADE (Grades of Recommendation, Assessment, Development and Evaluation) system was used for assessment of evidence quality. The quality of evidence classified by GRADE system is in 1 of 4 levels: high, moderate, low, and very low. Meta-analysis based on RCTs starts as high-quality evidence, and the confidence may be decreased because of the following reasons: study limitation, inconsistency of results, indirectness of evidence, imprecision, and reporting bias.[18]
2.5 Statistical analysis
Outcomes of continuous variables were expressed as the mean with standard difference. Mean difference (MD) and 95% confidence interval (CI) were calculated. Outcomes of discontinuous variables presented with events and total patients. Odds ratio (OR) and 95% CI were figured up. The primary outcome referred to PaO2/FiO2 or AaDO2 immediately after weaning from CPB. The secondary outcome referred to the PPCs, hospital stay, Qs/Qt immediately after weaning from CPB, and AaDO2 4 hours after weaning from CPB.
Homogeneity assumption was tested with I2 statistics. It is calculated as I2 = 100% × (Q – df)/Q, where Q is Cochran's heterogeneity statistic. Heterogeneity was suggested if P ≤0.10. An I2 value of 0%–24.9% indicated no heterogeneity, 25%–49.9% mild heterogeneity, 50%–74.9% moderate heterogeneity, and 75%–100% considerable heterogeneity.
Inverse variance statistical method was used in continuous variables data analysis, and the Mantel–Haenszel statistical method was used in discontinuous variables data analysis. Moreover, random-effects model was used for synthesis of the data. The publication biases were assessed by Egger's test for the asymmetry of funnel plots by regression methods. The presence of publication bias was indicated by Skewed and asymmetrical funnel plots. Sensitivity analyses were carried out for different subgroups according to a variety of differences in study design. All statistical analyses were executed by using Review Manager V.5.3 (RevMan, The Cochrane Collaboration, Oxford, UK). Significant differences were set at a 2-sided P value <0.05.
3 Results
3.1 Literature identification and study characteristics
A total of 1469 potentially eligible records were yielded from the initial database search (400 from PubMed, 878 from Embase, 191 from CENTRAL and 0 from other sources). After removing 488 duplicates, 4 independent authors screened 981 citations according to the inclusion criteria. Based on title and abstract, 954 records were excluded for various reasons (conference abstracts, letters, case reports, animal studies, pediatric patients, not RCTs in cardiac surgery, or irrelevant to the study). The remaining 27 full texts were screened, of which 10 citations were excluded for the following reasons: 3 studies had been published twice; 1 was an observational study; the full-text of 1 study was not available; and 5 studies assessed the effects of VCMs at the weaning from CPB. Finally, 17 citations were included in the meta-analysis (Fig. 1).[7,9,11,19–32] The main characteristics of the included trials are described in appendix (Table S1). The assessment of risk of bias regarding included studies is shown in appendix (Fig. S2, Supplemental content).
Figure 1 Flowchart of selecting process for meta-analysis.
3.2 Primary outcomes
There were 10 studies with 588 patients who reported PaO2/FiO2 ratio immediately after CPB. Our meta-analysis showed that there was a significant difference of PaO2/FiO2 between the ventilation and nonventilation groups in these studies (MD = 21.84; 95% CI = 1.30 to 42.37; P = 0.04; P for heterogeneity <0.01; I2 = 75% (Fig. 2).
Figure 2 Forest plot showing the effect of ventilation during CPB on PaO2/FiO2 ratio immediately after CPB. CPB = cardiopulmonary bypass, PaO2/FiO2 ratio = the ratio of partial pressure of arterial oxygen to fraction of inspired oxygen.
Data for the AaDO2 of ventilation during CPB were available from 10 RCTs in this analysis. Compared with the control group, ventilation during CPB was associated with significant improvement in AaDO2 immediately after weaning from CPB (MD = –50.17; 95% CI = –71.36 to –28.99; P <0.00001; P for heterogeneity <0.0001, I2 = 74%) (Fig. 3).
Figure 3 Forest plot showing the effect of ventilation during CPB on AaDO2 immediately after CPB. AaDO2 = alveolar to arterial oxygen tension difference, CPB = cardiopulmonary bypass.
To determine the source of heterogeneity, we made a sensitivity analysis and subgroup analysis according to ventilation strategies (Figs. 2 and 3). The sensitivity analysis showed that Alavi et al[20] and Altmay et al[19] separately had the greatest influence of heterogeneity on PaO2/FiO2 ratio and AaDO2. The subgroups were divided into the CPAP group and the low TV ventilation group based on the ventilation type. In the oxygenation index analysis, using CPAP during CPB showed a greater heterogeneity (I2 = 81%) than low TV ventilation (I2 = 62%). But there was no difference between 2 groups by using either CPAP (P = 0.1) or low TV ventilation strategy (P = 0.26). When it came to the AaDO2 in the subgroup analysis, there was a significant difference between 2 groups by using either CPAP (P = 0.004) or TV ventilation (P = 0.03).
3.3 Secondary outcomes
In secondary outcomes, the association between ventilation strategies during CPB and Qs/Qt immediately after weaning from CPB, the incidence of PPCs, hospital stay, and AaDO2 after 4 hours weaning from CPB were analyzed. The incidence of PPCs (OR = 0.79; 95% CI = 0.42 to 1.48; P = 0.46; P for heterogeneity = 0.18, I2 = 25%) and hospital stay (MD = 0.09; 95% CI = –23 to 0.41; P = 0.58; P for heterogeneity –0.16, I2 = 37%) did not differ significantly between 2 groups. However, AaDO2 4 hours after weaning from CPB (MD = –26.62; 95% CI = –48.18 to –5.06; P = 0.02; P for heterogeneity = 0.0010, I2 = 73%) and Qs/Qt immediately after weaning from CPB showed a significant difference between 2 groups (MD = –3.24; 95% CI = –4.48 to –2.01; P <0.00001; P for heterogeneity <0.75, I2 = 0%) (Fig. 4).
Figure 4 Forest plot showing the secondary outcomes of ventilation during CPB. CPB = cardiopulmonary bypass.
3.4 Quality of evidence
GRADE system grades of evidence were very low for PaO2/FiO2, AaDO2 immediately after weaning from CPB, and all the secondary outcomes (Fig. S3, Supplemental content).
4 Discussion
The main findings of this meta-analysis were ventilation during CPB indicated an increase in oxygenation index level and a decrease in AaDO2 level immediately after weaning from CPB in patients who underwent elective cardiac surgery. In addition, shunt fraction and AaDO2 4 hours after CPB were significantly different between groups. However, the PPCs and hospital stay did not differ significantly between ventilation and nonventilation group during CPB.
CPB-related pulmonary dysfunction is a multifactorial postoperative problem with high morbidity and mortality. Bignami et al[2] reviewed the literature concerning CPB-related respiratory insufficiency and lung damage, concluding that correct ventilation during CPB, as a paramount part of multidisciplinary approach, might diminish the occurrence of postoperative lung injury. A meta-analysis reported by Schreiber et al[33] showed that CPAP or VCMs administrated during CPB had a potential trend for lung protection based on some surrogate endpoints but no sustained effect postoperatively was found. Previous studies showed that the potential mechanisms of CPB-related lung dysfunction involved pulmonary atelectasis, intrapulmonary shunt, and change of systemic immune and inflammatory status.[2] This meta-analysis examined the efficacy and safety of ventilation during CPB in patients who underwent elective cardiac surgery. It is not only an update of Schreiber et al's study but also provides different comparison direction and endpoints. On one hand, our study analyzed the combined effect of ventilation during CPB compared with the nonventilation group. On the other hand, we performed subgroup analysis to compare the impact of separate ventilation strategies (CPAP or low TV ventilation alone). But the results from the above-mentioned comparison need to be interpreted with caution. The results from the combined effect of ventilation showed that ventilation during CPB could improve PaO2/FiO2 ratio immediately after weaning from CPB (P = 0.04) but the effect from CPAP or low TV ventilation alone got an opposite conclusion (P = 0.10; 0.26). The difference might be explained by the following: sample size: all included studies were small sample size trials and the subgroup analysis made the total sample size smaller, which thus could affect the results; the influence of PEEP: the use of PEEP was not uniform in each study, so the use of PEEP might be a potential confounding factor. In order to figure out the influence of PEEP, we performed subgroup analysis based on whether PEEP was used (Fig. S4, Supplemental content). Compared with the nonventilation group, the influence of low TV ventilation with or without PEEP on the PaO2/FiO2 ratio immediately after weaning from CPB was different from each other (low TV ventilation with PEEP: MD = 54.25, 95% CI = 3.66 to 104.84, P = 0.04; low TV ventilation without PEEP: MD = –3.79, 95% CI = –23.02 to 15.45, P = 0.70). Based on this result, we could conclude that the application of PEEP might improve oxygenation after CPB when the intervention measure was low TV ventilation. None of papers about CPAP mentioned the use of PEEP so we did not perform subgroup analysis about CPAP with or without PEEP. We also performed a funnel plot to access the publication bias of the literatures. In regard to PaO2/FiO2 immediately after weaning from CPB, the symmetry of the funnel plot was not very good suggesting that there might be publication bias (Fig. S5, Supplemental content). When it came to the AaDO2 immediately after weaning from CPB, the funnel plot was symmetrical in general showing that publication bias for the included studies was controlled passably (Fig. S6, Supplemental content).
A variety of lung-protective techniques, including CPAP, low TV ventilation, and VCMs, have been reported to be beneficial when applied during CPB.[2,5] As VCM is not a continuous ventilation type and has been recommended as a lung protective strategy in clinical practice at the weaning of CPB, VCM treatment alone was excluded and we mainly discuss CPAP or low TV ventilation during CPB. And owing to the endpoints of interest in the included studies were gathered at various time points, we chose the most frequent overlapped time point (immediately after CPB) to analyze the endpoints of patients. Besides, parameter details in the intervention group were set in a large range that is trials evaluating the effect of CPAP during CPB used CPAP from 5 to 15 cmH2O. Only 1 trial used CPAP of 15 cmH2O in one of the groups but this parameter setting was too high to get a better outcome of pulmonary function.[22] We just excluded these data and used a moderate CPAP from 5 to 10 cmH2O. In addition, the FiO2 used for CPAP or low TV ventilation ranged from 0.21 to 1.0. There were 2 trials that investigated the relationship of different FiO2 levels (FiO2 = 0.21; 1.0) with the PaO2/FiO2[22,32] and they suggested that perioperative hyperoxia was potentially harmful by increasing the expression of reactive oxygen species and decreasing receptors in cells.[34] Considering the lung injury caused by high FiO2, we excluded the group that using 100% oxygen in those 2 trials.
When interpreting the present results, several potential limitations should be taken into consideration. To begin with, the sample sizes of many included studies were limited. Clinical trial with small size and low quality might lead to bias and high heterogeneity (Fig. S2, Supplemental content). Presently, a large-scale RCT comparing the effects of no ventilation during CPB, CPAP with a PEEP of 5 cmH2O during CPB, and low TV ventilation of 2–3 mL/kg with a PEEP of 3–5 cmH2O during CPB in cardiac surgery is being performed (clinicaltrials.gov identifier NCT02090205). Nevertheless, the comparability of eligible cites was influenced by the heterogeneity of study endpoints and protocols. Moreover, owing to long-term outcomes that were rarely reported in the eligible cites and influenced by multiple factors such as the lung protection strategies before and after CPB, the main outcomes were surrogate endpoints that were not directly linked to long-term prognosis. Only 5 trials showed the incidence of PPCs and 7 trials referred to the length of hospital stay. Thus, we could not draw the conclusion that ventilation during CPB influences long-term prognosis of patients who underwent cardiac surgery.
5 Conclusion
Our meta-analysis indicated that ventilation during CPB might improve post-CPB oxygenation and gas exchange in patients who were scheduled to undergo cardiac surgery. However, long-term outcomes need to be further investigated through other large-sized and high-quality clinical trials. Different respiratory parameters setting during CPB, such as low or high FiO2 values and low TV ventilation with or without PEEP, may impact clinical outcomes.
Acknowledgments
The authors sincerely thank the authors of primary clinical studies.
Supplementary Material
Supplemental Digital Content
Abbreviations: AaDO2 = alveolar to arterial oxygen tension difference, ARDS = acute respiratory distress syndrome, BMI = body mass index, CI = confidence interval, CPAP = continuous positive airway pressure, CPB = cardiopulmonary bypass, FiO2 = the fraction of inspired oxygen, ICU = intensive care unit, IMV = intermittent mandatory ventilation, IL-10 = interleukin 10, MD = mean difference, MV = mechanical ventilation, OR = odds ratio, PaO2 = partial pressure of arterial oxygen, PaO2/FiO2 ratio = the ratio of partial pressure of arterial oxygen to fraction of inspired oxygen, PEEP = positive end-expiratory pressure, PPCs = postoperative pulmonary complications, RCTs = randomized controlled trials, TV = tidal volume, TNF-α = tumor necrosis factor-α, VCMs = vital capacity maneuvers.
Declaration: This document is a unique submission and it has never been published in any other medium, in part or in full.
DC, CC, and HY had the original idea and wrote the initial draft of the manuscript. HY had full access to all the data and took responsibility for the integrity of the data and the accuracy of the data analysis. BL had access to some data analysis and provided some guiding suggestions. YS and WW contributed substantially to the study design, data analysis and revision, and final approval of the manuscript. DC, CC, YS, WW and YM contributed equally to this article.
The authors have no funding and conflicts of interest to disclose.
Supplemental Digital Content is available for this article.
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Medicine (Baltimore)Medicine (Baltimore)MEDIMedicine0025-79741536-5964Wolters Kluwer Health 28328862MD-D-17-0088210.1097/MD.0000000000006457064573300Research ArticleClinical Trial/Experimental StudyPostoperative analgesia comparing levobupivacaine and ropivacaine for brachial plexus block A randomized prospective trialWatanabe Kunitaro MDaTokumine Joho MD, PhDa∗Lefor Alan Kawarai MD, MPH, PhDbMoriyama Kumi MD, PhDaSakamoto Hideaki MDcInoue Tetsuo MDcYorozu Tomoko MD, PhDaHanaoka. Kazuo a Department of Anesthesiology, Kyorin University School of Medicine, Shinkawa, Mitaka, Tokyo, Japanb Department of Surgery, Jichi Medical University, Yakushiji, Shimotsuke, Tochigi, Japanc Department of Anesthesia, Hino Munichipal Hospital, Tamadaira, Hino, Tokyo, Japan.∗ Correspondence: Joho Tokumine, Department of Anesthesiology, Kyorin University School of Medicine, Sinkawa, Mitaka, Tokyo, Japan (e-mail: ii36469@wa2.so-net.ne.jp).3 2017 24 3 2017 96 12 e645714 2 2017 25 2 2017 28 2 2017 Copyright © 2017 the Author(s). Published by Wolters Kluwer Health, Inc.2017This is an open access article distributed under the terms of the Creative Commons Attribution-Non Commercial-No Derivatives License 4.0 (CCBY-NC-ND), where it is permissible to download and share the work provided it is properly cited. The work cannot be changed in any way or used commercially without permission from the journal. http://creativecommons.org/licenses/by-nc-nd/4.0Abstract
Background:
On a pharmacologic basis, levobupivacaine is expected to last longer than ropivacaine. However, most reports of these anesthetics for brachial plexus block do not suggest a difference in analgesic effect. The aim of this study is to compare the postoperative analgesic effects of levobupivacaine and ropivacaine when used for treating ultrasound-guided brachial plexus block.
Methods:
A total of 62 patients undergoing orthopedic surgery procedures were prospectively enrolled and randomized to receive levobupivacaine (group L, N = 31) or ropivacaine (group R, N = 31). The duration of analgesia, offset time of motor block, need for rescue analgesics, and sleep disturbance on the night of surgery were recorded. Pain score was recorded on the day of surgery, and on postoperative days 1 and 2.
Results:
There was no difference in the time interval until the first request for pain medication comparing the two groups (group L: 15.6 [11.4, 16.8] hours; group R: 12.5 [9.4, 16.0] hours, P = 0.32). There was no difference in the duration of motor block (group L: 12.2 [7.6, 14.4] hours; group R: 9.4 [7.9, 13.2] hours, P = 0.44), pain score (P = 0.92), need for rescue analgesics (group L: 55%; group R: 65%, P = 0.6), or rate of sleep disturbance (group L: 61%, group R: 58%, P = 1.0) on comparing the two groups.
Conclusions:
There was no difference in postoperative analgesia comparing levobupivacaine and ropivacaine when used for brachial plexus block.
Keywords
brachial plexus blocklevobupivacainepostoperative analgesiaropivacaineOPEN-ACCESSTRUE
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1 Introduction
Levobupivacaine and ropivacaine are long-acting local anesthetics used for peripheral nerve blocks to provide prolonged postoperative analgesia. Levobupivacaine has been reported to have a longer duration of analgesic effect compared with ropivacaine when used for spinal and epidural anesthesia.[1–4] Levobupivacaine is more lipophilic compared with ropivacaine.[5] On a pharmacologic basis, levobupivacaine is considered to be more potent than ropivacaine with regard to providing postoperative analgesia. However, previous reports[6–8] have not shown a longer duration of postoperative analgesia when levobupivacaine is used for brachial plexus blocks compared with ropivacaine, except for a single report.[9]
Clinically, prolonged postoperative analgesia is important for postoperative pain management. Most appropriate local anesthetics are chosen for peripheral nerve block. We undertook this randomized prospective trial to compare the postoperative analgesic effects of levobupivacaine and ropivacaine when used for brachial plexus nerve blocks, performed with ultrasound guidance in patients undergoing orthopedic surgery procedures.
2 Methods
This study was reviewed and approved by the local ethics committee (Hino Municipal Hospital Ethical Review Board; Reception. No. 25-10) and was registered in the University Hospital Medical Information Network Center Clinical Trials Registration System (UMIN000012897). Written informed consent was obtained from patients scheduled to undergo surgery for upper limb fractures from April 2014 to March 2015. Exclusion criteria included allergy to local anesthetics, coagulation disorders, local skin infection at the block site, peripheral neuropathy, American Society of Anesthesiologists physical status ≥4, and patient refusal. Patients were randomly divided in two groups using levobupivacaine (group L) or ropivacaine (group R) for peripheral nerve block.
Brachial plexus block with an interscalene approach was performed in patients undergoing open reduction and internal fixation (ORIF) of humerus fracture and ORIF of elbow fracture. Brachial plexus blocks using an axillary approach were performed for patients undergoing ORIF of wrist fracture.
A randomized, double-blind selection of the groups was performed using the envelope method. A nurse not associated with the surgery shuffled and selected a sealed envelope from a box. The nurse prepared the solution for the nerve block after double checking with another nurse.
The solution for group L was a mixture of 15 mL of 0.5% levobupivacaine (Popscaine 5 mg/mL, Maruishi Pharmaceutical, Osaka, Japan) and 5 mL of saline (final concentration of the mixture was 0.375%). The solution for group R was a mixture of a mixture of 10 mL of 0.75% ropivacaine (Anapeine 7.5 mg/mL, AstraZeneca, Osaka, Japan) and 10 mL of saline (final concentration was 0.375%).
After preparing the solution, the nurse wrote down the operating room number and patient identification number, and placed this paper into another locked box. The key for this box was kept by an ethics committee member. In accordance with the rules of the protocol, these 2 nurses never met the anesthesiologist until completion of anesthesia, in order to ensure a blinded procedure. The anesthesiologists, orthopedic surgeons, and nurses in the ward remained blinded to the patients’ group allocation until the end of the study.
General anesthesia was induced with 2 mg/kg of propofol and 100–200 mcg of fentanyl intravenously. A laryngeal mask (ProSeal, Teleflex, San Diego, CA) was used, and anesthesia maintained with 4–6% desflurane. An ultrasound-guided peripheral nerve block was performed after placement of the laryngeal mask.[10] We used a 6–13 Hz high-frequency linear probe (HFL 38x EDGE, SonoSite Co., Bothell, WA) and a 22-G needle (Stimplex Ultra, B. Braun, Melsungen, Germany). We routinely used ultrasound guidance and nerve stimulators (Rasin Plex HRP-10, Hakko Co., Japan). Brachial plexus blocks with an interscalene approach or axillary approach were performed using 20 mL of 0.375% levobupivacaine (group L) or ropivacaine (group R). All nerve blocks were performed by anesthesiologists with extensive experience in ultrasound-guided nerve blocks. During surgery, ephedrine and/or phenylephrine were administered to maintain appropriate hemodynamics. At the end of surgery, 50 mg of flurbiprofen was routinely administered intravenously. On the first postoperative day, administration of 4 mg of oral lornoxicam after each meal was started and continued until the fifth postoperative day.
Postoperative pain was scored using the verbal rating scale (scale range: 0–5; 0: no pain, 5: strongest pain) on the day of surgery, as well as on the first and second postoperative days. Motor block was assessed using the modified Lovett rating scale[11] (0: complete paralysis, 1: almost complete paralysis, 2: pronounced mobility impairment, 3: slightly impaired mobility, 4: pronounced reduction of muscular force, 5: slightly reduced muscular force, 6: normal muscular force). The duration of analgesia (time interval until the first request for pain medication), offset time of motor block, need for rescue analgesics, and sleep disturbances during the night of surgery were recorded. Nurses were educated to assess pain score and neurologic evaluation before starting the study.
After surgery, patients were allowed to request rescue analgesics at any time, which included diclofenac (25 mg p.r.) with at least a 6-hour interval before re-administration. If the diclofenac did not relieve the pain, patients received pentazocine (15 mg i.v.) at an interval of at least 30 minutes. Administration time and amount of analgesic used were recorded.
2.1 Statistical analysis
A pilot study showed a mean difference in the time interval until the first request for pain medication using levobupivacaine and ropivacaine of 4.5 hours (standard deviation 6 hours). The sample size required for 80% power at ɑ = 0.05 was estimated to be 29 patients each for the experimental and control groups based on this pilot study. We planned for a total of 40 patients in each group.
The Wilcoxon rank test was used to compare continuous variables in the patient demographic data. Bonferroni correction to the multiple-comparison correction was used for pain scores. Time interval until the first request of pain medication and motor block were analyzed with the log-rank test using Kaplan–Meier survival curves. Fisher's exact test was used for American Society of Anesthesiologists physical status, rate of rescue analgesic requirement, and incidence of sleep disturbance. Numerical values are expressed as ratios (%) or as the median (interquartile range). P values <0.05 are considered statistically significant. Statistical analyses were performed with JMP 11 statistical software (JMP Statistical Discovery, Cary, NC).
3 Results
Sixty-two patients were enrolled in this study (Fig. 1). There was no difference in the demographic data comparing the two groups (Tables 1 and 2). There was no technical difficulty in performing ultrasound-guided peripheral nerve block in any patient.
Figure 1 Study flow diagram.
Table 1 Patient demographic data.
Table 2 Surgical procedures.
There was no difference in time interval until the first request for pain medication comparing the 2 groups (group L: 15.6 [11.4, 16.8] hours; group R: 12.5 [9.4, 16.0] hours, P = 0.32) (Fig. 2). There was no difference in the duration of motor block comparing the two groups (group L: 12.2 [7.6, 14.4] hours; group R: 9.4 [7.9, 13.2] hours, P = 0.44). There were no differences in pain scores at each time point after surgery comparing the two groups (P = 0.92) (Fig. 3). There were no differences in the need for rescue analgesics comparing the two groups (group L: 55%; group R: 65%, P = 0.6). There were no differences in the rate of sleep disturbance comparing the 2 groups (group L: 61%; group R: 58%, P = 1.0).
Figure 2 Duration of analgesia. There is no difference in the time interval until the first request for pain medication on comparing the 2 groups (P = 0.32): group R = ropivacaine, group L = levobupivacaine.
Figure 3 Postoperative pain scores. There is no difference in the postoperative pain scores on comparing the 2 groups (P = 0.92): group R = ropivacaine, group L = levobupivacaine. POD = postoperative day.
4 Discussion
This study shows that the postoperative analgesic effects of levobupivacaine and ropivacaine used for brachial plexus blocks are similar. Based on the pharmacology, levobupivacaine is expected to be associated with a longer duration of analgesia compared with ropivacaine.[5] Studies comparing postoperative analgesia in sciatic nerve block showed that levobupivacaine had a longer duration of postoperative analgesia compared with ropivacaine.[12–14] There are four previous studies comparing levobupivacaine and ropivacaine in the same concentrations used for brachial plexus blocks. However, 3 of the studies of brachial plexus block report no difference between these 2 agents. Liisanantti et al[6] reported that the duration of analgesia when using levobupivacaine for brachial plexus block was the same as that when using ropivicaine. Mageswaran and Choy[7] reported that patients receiving levobupivacaine and ropivicaine reported almost the same pain level at 6 hours after the operation. Casati et al[8] reported that there were no difference in postoperative pain scores comparing levobupivacaine and ropivacaine. However, Cline et al[9] showed a longer analgesic effect of levobupivacaine compared with ropivacaine.
The duration of postoperative analgesia after brachial plexous block is shorter than after sciatic nerve block. The reason for the difference in analgesic duration may be explained by pharmacodynamics. Serum levels of local anesthetics injected into the tissue rapidly increased after brachial plexus block compared with sciatic nerve block.[15,16] This suggests that local anesthetics used in brachial plexus block are rapidly absorbed. Therefore, a longer analgesic effect of levobupivacaine may be attenuated when used for brachial plexus block.
In the study we used 2 approaches to the brachial plexus block, the interscalene approach and an axillary approach. However, a previous report utilized another approach, the infraclavicular approach.[7] This may limit the ability to compare the results of this study with previous studies of brachial plexus block. We performed a subgroup analysis for the interscalene and axillary approaches, and found no statistically significant difference in all outcome measures.
This study shows that the analgesic effects of levobupivacaine and ropivacaine are not statistically significant when used for ultrasound guided brachial plexus block. This unexpected result may be explained by the pharmacodynamics of local anesthetics used for bracahal plexus blocks.
Acknowledgments
The authors thank contribution for the study to Dr. Shohei Siono (Hino Municipal Hospital), Dr. Kenji Nanao (Hino Municipal Hospital), and Toshiko Maeda (Hino Municipal Hospital).
Abbreviation: ORIF = open reduction and internal fixation.
This study was presented as an abstract at the Japanese Society of Regional Anesthesia 3rd Annual Congress 2015, Hirosaki, Japan.
The authors have no conflicts of interest to disclose.
==== Refs
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PMC005xxxxxx/PMC5371501.txt |
==== Front
Medicine (Baltimore)Medicine (Baltimore)MEDIMedicine0025-79741536-5964Wolters Kluwer Health 28328864MD-D-16-0782910.1097/MD.0000000000006461064613500Research ArticleSystematic Review and Meta-AnalysisPRISMA-combined Myeloperoxidase -463G/A gene polymorphism and coronary artery disease A meta-analysis of 4744 subjectsLi Yan-Yan PhDa∗Wang Hui PhDbQian Jin PhDaKim Hyun Jun MDcWu Jing-jing MDdWang Lian-sheng PhDbZhou Chuan-wei PhDaYang Zhi-Jian PhDbLu Xin-Zheng PhDbBellou. Abdelouahab a Department of Geriatricsb Department of Cardiology, First Affiliated Hospital of Nanjing Medical University, Nanjing, Chinac Department of Physiology, University of Cincinnati, Cincinnati, OHd Department of Nephrology, First Affiliated Hospital of Nanjing Medical University, Nanjing, China.∗ Correspondence: Yan-Yan Li, Department of Geriatrics, First Affiliated Hospital of Nanjing Medical University, NO 300 Guangzhou Road, Nanjing 210029, China (e-mail: lyynjmu123@126.com).3 2017 24 3 2017 96 12 e646131 12 2016 22 2 2017 23 2 2017 Copyright © 2017 the Author(s). Published by Wolters Kluwer Health, Inc.2017This is an open access article distributed under the terms of the Creative Commons Attribution-Non Commercial-No Derivatives License 4.0 (CCBY-NC-ND), where it is permissible to download and share the work provided it is properly cited. The work cannot be changed in any way or used commercially without permission from the journal. http://creativecommons.org/licenses/by-nc-nd/4.0Abstract
Background:
Myeloperoxidase (MPO) -463G/A gene polymorphism may be associated with an increased risk of developing coronary artery disease (CAD). Studies on the subject, however, do not provide a clear consensus. This meta-analysis was performed to explore the relationship between MPO gene -463G/A polymorphism and CAD risk.
Methods:
This meta-analysis combines data from 4744 subjects from 9 independent studies. By using fixed or random effect models, the pooled odds ratios (ORs) and their corresponding 95% confidence intervals (CIs) were assessed.
Results:
Our analysis found a significant association between MPO gene -463G/A polymorphism and CAD in the whole population under all genetic models: allelic (OR: 0.68, 95% CI: 0.54–0.85, P = 0.0009), recessive (OR: 0.41, 95% CI: 0.22–0.76, P = 0.005), dominant (OR: 0.682, 95% CI: 0.534–0.871, P = 0.002), homozygous (OR: 0.36, 95% CI: 0.16–0.79, P = 0.01), heterozygous genetic model (OR: 0.832, 95% CI: 0.733–0.945, P = 0.004), and additive (OR: 0.64, 95% CI: 0.46–0.90, P = 0.01), especially in the Chinese subgroup (P < 0.05). On the contrary, we found no such relationship in the non-Chinese subgroup (P > 0.05).
Conclusion:
The MPO gene -463G/A polymorphism is associated with CAD risk, especially within the Chinese population. The A allele of MPO gene -463G/A polymorphism might protect the people from suffering the CAD risk.
Keywords
-463G/Acoronary artery diseasegenemyeloperoxidasepolymorphismOPEN-ACCESSTRUE
==== Body
1 Introduction
Coronary artery disease (CAD) describes a family of ischemic diseases characterized by the occlusion of the coronary artery lumen by atheromatous plaque. Plaque from acute coronary syndrome (ACS) patients has increased levels of myeloperoxidase (MPO) and its oxidative products,[1] suggesting that MPO may be involved in the atherosclerotic process.
MPO, a member of the heme-peroxidase superfamily, is secreted by activated phagocytes and plays a crucial role in the antimicrobial innate immune response.[2] It has a 150-kDa homodimeric structure consisting of two 15-kDa light chains and 2 variable-weight heavy chains with a prosthetic heme group.[3] The primary reaction catalyzed by MPO is the degradation of hydrogen peroxide (H2O2) to hypochlorous acid (HOCl) and chloride anion (Cl-). Although HOCL has strong anti-microbial and detoxification properties, it can also cause oxidative damage to host tissue. MPO is secreted primarily by myelocytes, with up to 95% of the circulating MPO found in the blood vessels are derived from neutrophils.
The MPO gene, located in the 17q23.1, spans 14.638 kb and contains 12 exons and 11 introns.[4] The MPO -463G/A gene polymorphism involves a substitution of a guanine (G) for an adenine (A) in the upstream promoter region and acts in the cis-acting element for specificity protein 1 (SP1), a transcription factor. Four Glu repetitive sequences are included in the cis-acting element. The G nucleotide in this MPO -463G/A gene polymorphism establishes the central binding site for the SP1 transcription factor that can induce up to a 25-fold increase in MPO gene transcription. Substitution of this central guanine with adenine significantly decreases the MPO gene transcription by reducing the promoter's binding affinity, providing a plausible mechanism of how MPO gene transcription could influence CAD susceptibility.[5]
Many studies on the association between the MPO -463G/A gene polymorphism and CAD have been conducted, but have not provided a clear consensus. In 2006, Hao and Lu[6] also identified the G allele as an independent risk factor for CAD and the A allele as protective against CAD in the Chinese population, an effect attributed to the polymorphism's impact on transcription. Similarly, Nikpoor et al[7] found the A allele of the MPO -463G/A gene polymorphism to be associated with fewer CAD cases and concluded that the MPO gene -463 G/A polymorphism influences the CAD risk. On the contrary, Lin and Zhang[8] found no significant association of MPO -463G/A gene polymorphism with CAD in a separate Chinese population.
Given the lack of consensus on the relationship between MPO -463G/A gene polymorphism and CAD, we produced the current meta-analysis of 2454 CAD patients and 2290 controls.[9]
2 Methods
2.1 Publication search and inclusion criteria
The current study was approved by the Ethics Committee of the First Affiliated Hospital of Nanjing Medical University. The terms “coronary heart disease,” “myeloperoxidase,” “coronary artery disease,” “coronary heart disease,” and “polymorphism” were used to collect studies. The China Biological Medicine Database, China National Knowledge Infrastructure, Embase, PubMed, and the Web of Science were searched. Retrieved studies were published between 2001 and 2011 with the latest paper updated on February 21, 2017.
The selected studies had to conform to the following criteria: Assessment of the MPO -463G/A gene polymorphism and CAD; Diagnosis of CAD conducted in a manner consistent with criteria proposed by World Health Organization in 1979; and Genotypes in the control group follow the Hardy–Weinberg equilibrium (HWE).
2.2 Data extraction
Data were extracted as per a standardized protocol. Studies published in duplicates, those that did not meet inclusion criteria, and those with insufficient data were removed from the study. Overlapping data sets applied in separate publications were applied singly. The extracted data comprised the following items: the first author's name, publication year, region, number of genotypes, genotyping, matching criteria, total number of cases and controls.
2.3 Statistical analysis
In the present meta-analysis, 6 genetic models as the allelic (A allele distribution frequency of MPO -463G/A gene polymorphism), recessive (AA vs GA+GG), dominant (AA+GA vs GG), homozygous (AA vs GG), heterozygous (GA vs GG), and additive genetic models (A vs G) were used. The odds ratio (OR) and their corresponding 95% confidence interval (CI) were used to compare the relationship between MPO -463G/A gene polymorphism and CAD. The Chi-square based Q-test was used to calculate the heterogeneity between studies and the significance was set at P < 0.05 level.[10] The heterogeneity variation was evaluated by calculating the inconsistency index I2. If heterogeneity was detected, the random-effects model (Der Simonian and Laird method) would be used to estimate the pooled OR.[11] If no heterogeneity is detected, the fixed-effects model (Mantel–Haenszel method) would be adopted.[12] The pooled OR would be determined by using the Z test with significance set at P < 0.05 level.
The HWE was evaluated by using the Fisher exact test and the significance was set at P < 0.05 level. Potential publication bias would be estimated by using funnel plot. The Egger linear regression test on the natural logarithm scale of the OR was used to assess the funnel plot asymmetry and the significance was set at P < 0.05 level.[13] The STATA 12.0 software (StataCorp, College Station, TX) and review manager 5.0 were used to perform the statistical analysis.
3 Results
3.1 Studies and populations
Among the 19 papers produced from our initial search, 9 papers met the inclusion criteria. In total, data were extracted from 2454 CAD patients and 2290 controls (Table 1).[6–8,14–19] Patients were from China, Sweden, Canada, and Turkey and were of either Chinese or non-Chinese descent. Of the 10 studies removed from our initial search, 2 papers were duplicates and 3 were reviews on the topic. Two other papers did not address either MPO -463G/A gene polymorphism or CAD. Three studies were excluded for deviating from HWE.[20–22]
Table 1 Characteristics of the investigated studies of the association between MPO -463G/A gene polymorphism and CAD.
3.2 Pooled analyses
There was a significant association between MPO gene -463G/A polymorphism and CAD in the whole population under allelic (OR: 0.68, 95% CI: 0.54–0.85, P = 0.0009), recessive (OR: 0.41, 95% CI: 0.22–0.76, P = 0.005), dominant (OR: 0.682, 95% CI: 0.534–0.871, P = 0.002), homozygous (OR: 0.36, 95% CI: 0.16–0.79, P = 0.01), heterozygous genetic model (OR: 0.832, 95% CI: 0.733–0.945, P = 0.004), and additive genetic models (OR: 0.64, 95% CI: 0.46–0.90, P = 0.01) (Table 2, Figs. 1–6).
Table 2 Summary of meta-analysis of association of MPO -463G/A gene polymorphism and CAD.
Figure 1 Forest plot of CAD associated with MPO -463G/A gene polymorphism stratified by ethnicity under an allelic genetic model (distribution of A allelic frequency of MPO -463G/A gene polymorphism). A = adenine, CAD = coronary artery disease, G = guanine, MPO = myeloperoxidase.
Figure 2 Forest plot of CAD associated with MPO -463G/A gene polymorphism stratified by ethnicity under a recessive genetic model (AA vs GA+GG). A = adenine, CAD = coronary artery disease, G = guanine, MPO = myeloperoxidase.
Figure 3 Forest plot of CAD associated with MPO -463G/A gene polymorphism stratified by ethnicity under a dominant genetic model (AA+GA vs GG). A = adenine, CAD = coronary artery disease, G = guanine, MPO = myeloperoxidase.
Figure 4 Forest plot of CAD associated with MPO -463G/A gene polymorphism stratified by ethnicity under a homozygous genetic model (AA vs GG). A = adenine, CAD = coronary artery disease, G = guanine, MPO = myeloperoxidase.
Figure 5 Forest plot of CAD associated with MPO -463G/A gene polymorphism stratified by ethnicity under a heterozygous genetic model (GA vs GG). A = adenine, CAD = coronary artery disease, G = guanine, MPO = myeloperoxidase.
Figure 6 Forest plot of CAD associated with MPO -463G/A gene polymorphism stratified by ethnicity under an additive genetic model (total A vs total G). A = adenine, CAD = coronary artery disease, G = guanine, MPO = myeloperoxidase.
Under the heterozygous genetic model, no heterogeneity was detected in the whole population. Although the whole population displayed significant heterogeneity under all genetic models (Pheterogeneity < 0.05), heterogeneity was only detected under the additive model when looking at the Chinese subgroup (Pheterogeneity > 0.05). In contrast, the non-Chinese subgroup still showed significant heterogeneity under the allelic, recessive, homozygous, and additive genetic models (Pheterogeneity < 0.05). This suggests ethnicity as a primary source of the heterogeneity in the current meta-analysis (Table 2, Figs. 1–6).
In the Chinese subgroup, a significant association between them was found under the allelic (OR: 0.58, 95% CI: 0.47–0.71, P = 3.58 × 10–7, Pheterogeneity = 0.31), recessive (OR: 0.29, 95% CI: 0.16–0.55, P = 0.0001, Pheterogeneity = 0.38), dominant (OR: 0.573, 95% CI: 0.452–0.725, P = 3.48 × 10–6, Pheterogeneity = 0.37), homozygous (OR: 0.24, 95% CI: 0.11–0.50, P = 0.0002, Pheterogeneity = 0.26), heterozygous (OR: 0.629, 95% CI: 0.498–0.793, P = 9.23 × 10–5, Pheterogeneity = 0.40), and additive genetic models (OR: 0.53, 95% CI: 0.36–0.79, P = 0.002, Pheterogeneity = 0.004).
In the non-Chinese subgroup, no significant association between them was found under the allelic (OR: 0. 85, 95% CI: 0.62–1.18, P = 0.34, Pheterogeneity = 0.02), recessive (OR: 0.58, 95% CI: 0.24–1.41, P = 0.23, Pheterogeneity = 0.01), dominant (OR: 0.883, 95% CI: 0.642–1.213, P = 0.441, Pheterogeneity = 0.09), homozygous (OR: 0.61, 95% CI: 0.16–2.34, P = 0.47, Pheterogeneity = 0.001), heterozygous (OR: 0.934, 95% CI: 0.803–1.086, P = 0.377, Pheterogeneity = 0.322), and additive genetic models (OR: 0.91, 95% CI: 0.49–1.69, P = 0.77, Pheterogeneity < 0.0001).
3.3 Bias diagnostics
The publication bias of the individual studies was evaluated by the funnel plot and Egger test. No visual publication bias was detected in the funnel plot under the allelic genetic model (Fig. 7). No statistically significant difference was detected in the Egger test that implies no publication bias in the present meta-analysis existed by using additive genetic model (T = -2.08, P = 0.076) (Fig. 8).
Figure 7 Funnel plot for studies of CAD associated with MPO -463G/A gene polymorphism under an allelic genetic model (distribution of A allelic frequency of MPO gene). The horizontal and vertical axis correspond to the OR and confidence limits. A = adenine, CAD = coronary artery disease, G = guanine, MPO = myeloperoxidase, OR = odds ratio, SE = standard error.
Figure 8 Begg funnel plot for studies of the association of CAD associated MPO -463G/A gene polymorphism under an additive genetic model (total A vs total G). The horizontal and vertical axis correspond to the OR and confidence limits. A = adenine, CAD = coronary artery disease, G = guanine, MPO = myeloperoxidase, OR = odds ratio, SE = standard error.
4 Discussion
Our meta-analysis on the relationship between MPO gene -463G/A polymorphism and CAD found significant correlation under allelic (OR: 0.68), recessive (OR: 0.41), dominant (OR: 0.682), homozygous (OR: 0.36), heterozygous (OR: 0.832), and additive genetic models (OR: 0.64) in the whole population. When we focused our analysis to the Chinese subgroup, the correlation grew stronger with lower ORs under all genetic models: allelic (OR: 0.58), recessive (OR: 0.29), dominant (OR: 0.573), homozygous (OR: 0.24), heterozygous (OR: 0.629), and additive (OR: 0.53). In the non-Chinese subgroup, we found no significant correlation under allelic (OR: 0. 85), recessive (OR: 0.58), dominant (OR: 0.883), homozygous (OR: 0.61), heterozygous (OR: 0.934), and additive genetic models (OR: 0.91). Summarily, our data suggest that the MPO gene -463G/A polymorphism is associated with CAD susceptibility, particularly in the Chinese population with the A allele of MPO gene -463G/A polymorphism playing a protective role in the disease process.
MPO is an essential part of the host immune response, but its expression is closely linked to atherosclerotic formation. It is used clinically as a marker for local inflammation in the coronary artery and has even demonstrated to be an independent marker for myocardial infarction.[23,24] High plasma MPO levels are also correlated with cardiovascular events such as ACS and heart failure.[25]
The primary reaction catalyzed by MPO is the formation of cytotoxic hypochlorous acid. This is the signature reaction that powers the “respiratory burst” of neutrophils. The oxidation of tyrosine is also an important reaction catalyzed by MPO. MPO could translate L-tyrosine to cheese ammonia acyl and acquire hydrogen through Diallyl heartland of methyl groups of the polyunsaturated fatty acid and launch the lipid peroxidation by forming the tyrosine cross-link in the protein.
Although MPO is an important component of the innate immune response, MPO-derived oxidative agents (hypochlorous acid, 3-chloration tyrosine, cheese ammonia acyl, and nitrotyrosine) can be produced in excess, resulting in oxidative stress and tissue damage. Hypochlorous acid is capable of degrading proteoglycan and decreasing the adhesion between extracellular matrix and endothelial cells, ultimately causing shearing of endothelial cells from the vessel wall and impaired endothelial function.[26]
MPO can also attenuate the fibrous cap of atherosclerotic plaques and enlarge their lipids centers, making them more prone to rupture. MPO-generated nitric oxide (NO) derivatives can also launch pathological incidents in the AS cascades. MPO could take advantage of the NO with the protective factor as the substrate, as well as produce various potential causing atherosclerosis factors. These elements are associated with the vulnerability of endothelium dysfunction and foam cells depositing in the atheromatous plaque.[27]
Lastly, MPO is a key enzyme in oxidizing both low and high-density lipoprotein (LDL/HDL). High levels of LDL, the main carrier of cholesterol through the body, are primary factor in atherosclerosis. Research shows that in order to promote the vascular disease process, LDL must be oxidatively modified to form oxidized LDL (ox-LDL).[28] Ox-LDL damages the artery intima and induces expression of endothelial adhesion molecules, colony-stimulating factors, vascular smooth muscle growth factors, and monocyte chemotaxis protein-1. The ox-LDL also induces the transformation of smooth muscle cells and monocytes to foam cells that accumulate under the endothelial cells and form the fatty streaks.
Fourth, MPO also promotes the HDL oxidation, and influences reverse cholesterol transport. HDL interactions with vascular endothelial cells are seen to be protective of vascular function by transporting redundant cellular cholesterol to the liver tissue. Thus, it could inhibit the platelet activation, increase the NO synthesis and release, and adjust the adhesion molecules expression in the endothelial cells and the endothelin secretion.[29] One study found that hypochlorous acid produced from MPO could oxidize apolipoprotein A-I (apo A-I) and cause reduced reverse cholesterol transport.[30] Its underlying possible mechanism is that MPO could influence the reaction of apo A-I and scavenger receptor B I.[31]
Despite the limitations of the current meta-analysis, we hope that this study will offer other researchers a comprehensive and improved perspective on the relationship between the MPO gene -436G/A polymorphism and CAD over past meta-analyses. Although the study performed by Chang et al[32] in 2013 found a significant correlation between the gene polymorphism and CAD, the small data set limited the conclusions that could be drawn from it. By combining data from 9 studies, in contrast to the 5 of Chang, we hope to provide a more comprehensive perspective. In 2014, Chen et al[33] also found a significant correlation. They found that the A allele of MPO -463G/A gene polymorphism is associated with decreased risk of CAD except in the Europeans. Deviation of these studies, which were also used in the works of Yin et al,[20] Li et al,[21] and Chen et al,[22] limits their objectivity. Work produced by Tang et al[34] in 2013 also included studies that were not at HWE.[21,22] In addition, the individual study by Du et al[35] was carried out by the similar author group to the study by Wu et al.[36] Hence, their results were not as accurate as that from the current meta-analysis.
In addition to the inevitable measurement errors, the large-scale researches on the relationship between CAD and MPO gene -463G/A polymorphism are still needed. Inevitably, plasma MPO levels are influenced by other genetic polymorphisms, such as the MPO gene -129A/G polymorphism and environmental factors, such as ethnicity, smoke, hypertension, hyperlipidemia, and diabetes mellitus.
5 Conclusions
The present meta-analysis indicates that the MPO gene -463G allele might increase CAD risk, especially in the Chinese population. It is our hope that the conclusion assists researchers in the search for an individualized treatment for CAD and that future studies will build upon this study to further elucidate this important area of research.
Acknowledgment
The authors thank all the colleagues working in the Department of Geriatrics, the First Affiliated Hospital of Nanjing Medical University.
Abbreviations: A = adenine, ACS = acute coronary syndrome, Apo A-I = ApolipoproteinA-I, CAD = coronary artery disease, CIs = confidence intervals, Cl- = chloride anion, G = guanine, H2O2 = hydrogen peroxide, HOCl = hypochlorous acid, HWE = Hardy–Weinberg equilibrium, LDL/HDL = low and high-density lipoprotein, MPO = myeloperoxidase, ORs = odds ratios, ox-LDL = oxidized low density lipoprotein, SP1 = specificity protein 1.
Y-YL and HW contribute equally to this work.
Authorship: Conceived and designed the meta-analysis: YL and LW. Performed the meta-analysis: YL and HW. Analyzed the data: YL, JQ, and CZ. Contributed material/analysis tools: YL. Wrote the manuscript: YL. Reference collection and data management: YL and JW. Statistical analyses and paper writing: YL, HK, and ZY. Study design: YL and XL.
Funding/support: This work was funded by the National Natural Science Foundation of China (NSFC 81100073 to Dr Y-YL), Excellent Young and Middle-Aged Teachers Assistance Program of Nanjing Medical University for Dr Y-YL (2013–2015, JX2161015034), Jiangsu Overseas Research & Training Program for University Prominent Young & Middle-aged Teachers and Presidents (2014), and the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD). This work was also funded by the Natural Science Foundation of Jiangsu Province (BK 2012648 to Dr HW), “six talent peaks” project in Jiangsu Province (2015-WSN-033).
The authors report no relationships that could be construed as a conflict of interest.
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Medicine (Baltimore)Medicine (Baltimore)MEDIMedicine0025-79741536-5964Wolters Kluwer Health 28328865MD-D-16-0730310.1097/MD.0000000000006482064827100Research ArticleClinical Case ReportNovel management of distal tibial and fibular fractures with Acumed fibular nail and minimally invasive plating osteosynthesis technique A case reportWang Tie-Jun MDaJu Wei-Na MDbQi Bao-Chang MMa∗Mayr. Johannes a Division of Orthopedic Traumatologyb Department of Neurology, the First Hospital of Jilin University, Changchun, China.∗ Correspondence: Bao-Chang Qi, Division of Orthopedic Traumatology, the First Hospital of Jilin University, No. 71 Xinmin Street, Changchun 130021, China (e-mail: qibaochang1@163.com).3 2017 24 3 2017 96 12 e64825 12 2016 3 3 2017 6 3 2017 Copyright © 2017 the Author(s). Published by Wolters Kluwer Health, Inc.2017This is an open access article distributed under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike 4.0 License, which allows others to remix, tweak, and build upon the work non-commercially, as long as the author is credited and the new creations are licensed under the identical terms. http://creativecommons.org/licenses/by-nc-sa/4.0Abstract
Rationale:
Anatomical characteristics, such as subcutaneous position and minimal muscle cover, contribute to the complexity of fractures of the distal third of the tibia and fibula. Severe damage to soft tissue and instability ensure high risk of delayed bone union and wound complications such as nonunion, infection, and necrosis.
Patient concerns:
This case report discusses management in a 54-year-old woman who sustained fractures of the distal third of the left tibia and fibula, with damage to overlying soft tissue (swelling and blisters). Plating is accepted as the first choice for this type of fracture as it ensures accurate reduction and rigid fixation, but it increases the risk of complications.
Diagnosis:
Closed fracture of the distal third of the left tibia and fibula (AO: 43-A3).
Interventions:
After the swelling was alleviated, the patient underwent closed reduction and fixation with an Acumed fibular nail and minimally invasive plating osteosynthesis (MIPO), ensuring a smaller incision and minimal soft-tissue dissection.
Outcomes:
At the 1-year follow-up, the patient had recovered well and had regained satisfactory function in the treated limb. The Kofoed score of the left ankle was 95.
Lessons:
Based on the experience from this case, the operation can be undertaken safely when the swelling has been alleviated. The minimal invasive technique represents the best approach. Considering the merits and good outcome in this case, we recommend the Acumed fibular nail and MIPO technique for treatment of distal tibial and fibular fractures.
Keywords
Acumed fibular naildistal tibial and fibular fracturesminimally invasive plating osteosynthesis (MIPO)OPEN-ACCESSTRUE
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1 Introduction
Anatomical characteristics, such as subcutaneous position and minimal muscle cover, contribute to the complexity of fractures of the distal third of the tibia and fibula. Severe damage to soft tissue and extreme instability ensure high risk of delayed bone union and wound complications such as dehiscence and infection.[1,2] Plating is accepted as the first choice of stabilization for this type of fracture and ensures accurate reduction and rigid fixation,[3] but increases the risk of complications due to the dissection of bone and soft tissue required in this technique. Recently, a novel technique—minimally invasive plating osteosynthesis (MIPO)—has been developed to alleviate soft tissue damage associated with plating.[4] Fibular fixation plays a positive role in reducing tibial displacement and improving mechanical stability of the entire lesion,[5] but the technique of plating the lateral malleolus has an associated with a complication rate of up to 30%.[6] Therefore, the fibular nail, which requires a smaller incision and minimal soft-tissue dissection, poses an alternative technique for fixation of the lateral malleolus.
We report a case with fractures of the distal third of the left tibia and fibula with associated severe damage to soft tissue. The fractures were successfully reduced and fixed with the Acumed fibular nail (Acumed LLC, Hillsboro, Oregon) using the MIPO technique, with satisfactory outcomes.
2 Case presentation
A 54-year-old woman sustained a fall and was admitted to our hospital 3 hours later with complaints of pain in the distal part of the left leg and limited mobility. On physical examination, the left distal leg showed severe swelling with several large blisters overlying the region; the distal pulses were palpable. The examination of the neurovascular system revealed no abnormalities of the lower extremities, and there was no compartment syndrome. She had no notable comorbidities. Radiography revealed fractures of the distal third of the left tibia and fibula, but the ankle articular surfaces were intact (Fig. 1A and B). Therefore diagnosis of a closed fracture of the distal third of the left tibia and fibula (AO: 43-A3) was made. Initially, strategies for detumescence and symptomatic treatment were administered. The left foot was elevated using a pillow, and oral detumescent drugs were used. A brace was used for temporary fracture fixation. Two weeks later, the swelling had alleviated and the blisters appeared wizened (Fig. 1C and D), and operative stabilization was conducted for early functional rehabilitation. The result of preoperative blood routine examination was normal.
Figure 1 Preoperative plain radiographs and photographs. (A and B) Anteroposterior and lateral views showing fractures of the distal third of the tibia and fibula. (C and D) Photographs of medial and lateral appearance of soft-tissue injury showing the wizened blisters.
2.1 Surgical technique
Under general anesthesia, with tourniquet application, and in the supine position on a radiolucent table the patient underwent fracture reduction. In the distal tibia, a medial distal tibia locking compression plate (LCP, size: 10 holes, DePuy Synthes, Oberdorf, Switzerland) of adequate length was applied over the medial surface and we performed closed indirect reduction using fluoroscopic guidance. The reduced fracture of the tibia was fixed temporarily by K-wires. Thereafter, a 4-cm vertical incision was made at the center of the medial malleolus and a subcutaneous tunnel was opened with a periosteal dissector. The selected plate was tunneled proximally and subcutaneously across the fracture site and positioned anteriorly over the tibial crest. Thereafter, 3.5-mm locking screws were inserted after ensuring satisfactory reduction by orientation using a similar-sized LCP. Then, the fibular fracture was fixed after closed reduction; a 1 cm incision was made just below the lateral end of the distal fibula. The distal fibular metaphysis was prepared with a cannulated 6.1 mm drill over a 1.6 mm guide wire. The diaphysis was then reamed by hand using a 3.1 mm reamer and the Acumed fibular nail (diameter: 3 mm, length: 180 mm) was inserted in a retrograde manner. Two 5 mm incisions were made at the ankle laterally and the nail was locked using two 2.7 mm screws through the eyelet of the nail in the lateral malleolus. The tourniquet was removed and all incisions were sutured after ensuring hemostasis. Intraoperative radiographs showed correct reduction of the fractures (Fig. 2A–D).
Figure 2 Intraoperative radiographs and clinical postoperative pictures. (A–D) Anteroposterior and lateral intraoperative views showing correct reduction of fractures. (E and F) At 1 week after surgery, clinical pictures reveal the incisions are healing well.
Intravenous antibiotic prophylaxis was initiated routinely 30 minutes before surgery and was then continued for another 24 hours postoperatively. We followed standard institutional protocols of postoperative routine dressing change, infection prevention measures, and symptomatic therapy. Results of blood routine examination at postoperative day 3 were normal. The patient was instructed to undergo physiotherapy with muscle strengthening and joint function exercises. One week after surgery, the incisions were healing well (Fig. 2E and F). Two weeks postoperatively the patient was discharged. Partial weight-bearing was commenced at 6 weeks postoperatively and full weight-bearing was permitted 3 months after the surgery. Radiographs taken postoperatively revealed correct fracture reduction (Fig. 3A and B). At the 1-year follow-up, there were no localized tenderness, axial knocking pain, or abnormal movement; radiography revealed good fracture healing with abundant callus across the fracture site and obliteration of the fracture line (Fig. 3C and D) and the patient had attained satisfactory restoration of function in the injured leg. The patient could walk freely. The Kofoed score of the left ankle was 95.
Figure 3 Postoperative radiographs. (A and B) Anteroposterior and lateral views showing correct reduction of fractures. (C and D) At 1 year after surgery, radiographs revealed that the fracture healed well with abundant callus formation.
3 Discussion
Distal tibial fractures remain among the most substantial therapeutic challenges that confront the orthopedic traumatologist. Although conservative management of these fractures has been described,[7,8] unstable distal tibial and fibular fractures are most often treated by open reduction and internal fixation (ORIF) techniques that have not changed significantly for many years and are associated with a high rate of complications including infection, soft-tissue necrosis, and nonunion because of the poor blood supply and a thin layer of soft-tissue cover, especially in patients with osteoporosis. The incidence of complications following ORIF in the elderly is up to 40%,[9] and is much higher in patients with systemic disease, particularly diabetes and neuropathy,[10] and in smokers.[11]
The MIPO technique is established for managing fractures of the distal third of the tibia that has a reliable fixation approach while preserving the osseous vascularity and hematoma, thus facilitating better biological repair. The technique can be used for the fractures with vertical split where nailing is not suitable. Due to the preserved vascularity and limited exposure, there is a lower incidence of delayed union, nonunion, or infection.[1]
For the distal fibular fracture, minimally invasive plating techniques, which are carried out through smaller wounds (3–4 cm), are more technically challenging.[12] The fibular nail may be an alternative method of fixing the distal fibular fracture as it requires a smaller incision (1 cm[13] vs 8 cm[14] for lateral plating) and less extensive soft-tissue dissection. Successful outcomes have been reported with different nails. Bugler et al[15] reported good 8-year follow-up results in 105 patients treated with the Acumed fibular nail. Both the MIPO technique and fibular nail have the same minimally invasive advantage and, therefore, are suitable for fractures with poor soft-tissue conditions.
Numerous treatment options are available for distal fractures of the tibia and fibula—plating for both the bones, nailing for tibial fracture combined with plating for fibular fractures, nailing for both the bones, plating for the tibial fracture combined with nailing for fibular fractures. The most appropriate treatment option is selected based on fracture type, soft-tissue condition, and stability of the fracture. In the reported case with the poor condition of the overlying soft tissue (blisters) we choose the least invasive technique (Acumed fibular nail) for the stabilization of the fibular fracture. Due to the lower fracture line of the tibia, we selected the MIPO technique with LCP for stabilization. At present, the patient has recovered very well with restoration of good function in the injured leg without any complication. Based on the experience from this case, the operation can be undertaken safely after the swelling is alleviated. Considering the good outcome in this case, we recommend use of the Acumed fibular nail and MIPO technique for treatment of distal tibial and fibular fractures.
Abbreviations: LCP = locking compression plate, MIPO = minimally invasive plating osteosynthesis.
T-JW and W-NJ contributed equally to this work.
Funding: This work was supported by the Academy & Research Foundation for Young Scientists (grant no. MJR20160015), the National Natural Science Foundation of China (grant no. 81500911), and AOTrauma Asia Pacific (Ref: AOTAP15-01).
Consent: The Institutional Review Board of Jilin University approved the publication of this case report. Informed consent was obtained from the patient.
The authors have no conflicts of interest to disclose.
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Management of fractures of the distal third tibia by minimally invasive plate osteosynthesis—a prospective series of 50 patients . J Clin Orthop Trauma
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[2] Xue XH Yan SG Cai XZ
Intramedullary nailing versus plating for extra-articular distal tibial metaphyseal fracture: a systematic review and meta-analysis . Injury
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Surgical treatment of nonarticular distal tibia fractures . J Am Acad Orthop Surg
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[5] Bonnevialle P Lafosse JM Pidhorz L
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[6] Lamontagne J Blachut PA Broekhuyse HM
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[10] Wukich DK Joseph A Ryan M
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[11] Nasell H Ottosson C Tornqvist H
The impact of smoking on complications after operatively treated ankle fractures—a follow-up study of 906 patients . J Orthop Trauma
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[12] Hess F Sommer C
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JSLSJSLSjslsjslsJSLSJSLS : Journal of the Society of Laparoendoscopic Surgeons1086-80891938-3797Society of Laparoendoscopic Surgeons Miami, FL JSLS.2016.0010610.4293/JSLS.2016.00106Scientific PaperLaparoscopic Rectopexy with Urinary Bladder Xenograft Reinforcement Mehta Aradhana BSUniversity of Nevada School of Medicine, Reno, Nevada, USA.Afshar Rami PA-CUniversity of Nevada School of Medicine, Reno, Nevada, USA.Warner David L. BSUniversity of Nevada School of Medicine, Reno, Nevada, USA.Gardner Amy PA-CUniversity of Nevada School of Medicine, Reno, Nevada, USA.Ackerman Ellen PA-CUniversity of Nevada School of Medicine, Reno, Nevada, USA.Brandt Jared PA-CUniversity of Nevada School of Medicine, Reno, Nevada, USA.Sasse Kent C. MD, MPHUniversity of Nevada School of Medicine, Reno, Nevada, USA.Disclosures: Dr. Sasse receives speaking honoraria from ACell, Columbia, Maryland, USA. The remaining authors report no disclosures.
Address correspondence to: David L. Warner, BS, University of Nevada School of Medicine, 75 Pringle Way, Suite 804, Reno, NV 89509. Telephone: 775-829-7999, Fax: 775-829-7970, E-mail: dwarner@medicine.nevada.eduJan-Mar 2017 21 1 eJSLS.2016.00106© 2017 by JSLS, Journal of the Society of Laparoendoscopic Surgeons.2017Society of Laparoendoscopic Surgeons, Inc.This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial No Derivatives License (http://creativecommons.org/licenses/by-nc-nd/3.0/us/), which permits for noncommercial use, distribution, and reproduction in any medium, provided the original work is properly cited and is not altered in any way.Background and Objectives:
Rectal prolapse is often repaired laparoscopically, frequently with the use of reinforcement material. Both synthetic and biologically derived materials reduce recurrence rate compared to primary suture repair. Synthetic mesh introduces potential complications such as mesh erosion, fibrosis, and infection. Urinary bladder matrix (UBM) represents a biologically derived material for reinforcement of rectal prolapse repair with the potential to improve durability without risks of synthetic materials. The objective of the study is to evaluate the effectiveness, durability, and functional result of laparoscopic rectopexy using urinary bladder matrix xenograft reinforcement at three years follow up.
Methods:
The 20 cases presented describe rectal prolapse repair by means of laparoscopic rectopexy with presacral UBM reinforcement. Patients were followed up for an average of 3 years and assessed with interviews, physical examination, manometry, and the fecal incontinence severity index (FISI).
Results:
Each repair was completed laparoscopically. UBM exhibited favorable handling characteristics when sutured to the sacrum and the lateral rectal walls. One patient underwent laparoscopic drainage of a postoperative abscess; no other complications occurred. In 3 years of follow-up, there have been no full-thickness recurrences, erosions, reoperations, or long-term complications. Two patients exhibited a small degree of mucosal prolapse on follow-up physical examination that did not require surgery. Three-year FISI scores averaged 8 (range, 0–33 of a possible 61), indicating low fecal incontinence symptomatology. Follow-up anorectal manometry was performed in 9 patients, showing mixed results.
Conclusion:
Surgeons may safely use laparoscopic rectopexy with UBM reinforcement for repair of rectal prolapses. In this series, repairs with UBM grafts have been durable at 3-year follow-up and may be an alternative to synthetic mesh reinforcement of rectal prolapse repairs. Future studies may compare the advantages and cost-effectiveness of reinforcement materials for rectal prolapse repair.
Laparoscopic rectopexyRectal prolapseUrinary bladder matrix
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INTRODUCTION
Rectal prolapse results in a severe adverse impact on the patient's quality of life and is often accompanied by fecal incontinence and a need to manually reduce the prolapse.1 Repair techniques have a high rate of recurrence and a mixed record of resolving the symptoms of fecal incontinence that often accompany the prolapse.2,3 Both synthetic and biologically derived materials reduce the recurrence rate compared with primary suture repair4; however, synthetic mesh introduces potential complications, such as mesh erosion, fibrosis, and infection.2,4–11 Although several repair techniques are used today, laparoscopic rectopexy with either suture alone or graft reinforcement and with or without sigmoidectomy, is a commonly performed surgical repair technique.2,12–14 Although there is no clear consensus, increasing concerns have been raised in the literature with respect to the complications of synthetic mesh repairs.2,4–11 Rectal wall mesh erosion requiring major surgery has been reported in both posterior and anterior rectopexy with synthetic mesh.4–11 Biologically derived materials, proposed as an alternative to minimize mesh-related complications of erosion, pain, and infection, are increasingly used for rectal prolapse repairs.13 However, it is not known whether the use of biologically derived materials in rectopexy repairs provides a safe and durable repair.11,13 UBM consists of the epithelial basement membrane and lamina propria of the porcine urinary bladder. After decellularization, it retains biochemical diversity, an architecture that is similar to the normal tissue, and strong mechanical behavior.14,15 UBM has shown effectiveness in animal studies and human clinical use for management of complex wounds and reinforcement of surgically repaired soft tissue with connective tissue remodeling in anatomic settings as diverse as esophageal, hiatal hernia, urinary bladder, pelvic floor, and body wall repair.16–20 Use of UBM has been documented in pelvic organ prolapse.19,20
METHODS
Twenty cases of rectal prolapse repair with rectopexy and UBM graft reinforcement, without sigmoidectomy, were performed between 2010 and 2016. Increased prolapse requiring manual reduction and symptoms including pain, bleeding, and fecal incontinence were the indications for surgical repair, and all patients experienced severe, circumferential, full-thickness grade V rectal prolapse, per the Oxford rectal prolapse grading system.21 Nineteen female and 1 male patient, with an average age of 64 years and an average BMI of 25, underwent surgery. Patient information is presented in Table 1. Laparoscopic repair was performed in all 20 cases, with full pelvic rectal mobilization followed by UBM device placement (MatriStem Surgical Matrix PSMX; ACell, Inc., Columbia, Maryland, USA) in the presacral position and rectopexy. In each case, the rectum was elevated laparoscopically from its attachments in the pelvis, with division of the lateral stalks below the pelvic floor (Figures 1 and 2). The UBM 10 × 15-cm graft was hydrated in normal saline for 20 minutes and then positioned in the presacral position and secured to the sacral periosteum using 0 Ethibond sutures (Ethicon, Somerville, New Jersey, USA) and to the lateral rectal wall with absorbable sutures (Figure 3).
Table 1. Patient and Procedure Information
Patient and Surgery Characteristics Data
N 20
Mean age, years (range) 64 (35–91)
Female/male, n 19/1
Mean BMI (range) 25 (18–45)
Mean length of stay, days (range) 1.9 (1.0–5.5)
Mean operative time, minutes (range) 68 (42–148)
Complication 1 (abscess, drained laparoscopically)
Follow-up, months (range) 36 (9–72)
Recurrence 0 full thickness; 2 mucosal prolapse not requiring surgery
3-Year FISI score (median) 8 ±12 (0–33 out of possible 61)
Figure 1. Large rectal prolapse elevated, securing left side of rectal wall.
Figure 2. Securing UBM graft in presacral position.
Figure 3. Completing reinforcement of repair with UBM graft.
After an average of 3 years, 17 patients completed the fecal incontinence severity index (FISI) survey regarding repair durability and fecal continence via telephone or in-person interview, with institutional review board approval. Nine of the patients underwent manometry evaluations of the anorectal sphincter.
RESULTS
A total of 20 patients underwent a laparoscopic rectopexy, of which 1 was lost to follow-up. The remaining 19 patients were evaluated with follow-up office examination, and 17 completed a survey that included an assessment of continence. Each repair was successful, with no patients requiring further surgery for repair of the prolapse. The handling properties of the UBM material were favorable, including ease of inserting via a 12-mm trocar, maneuvering into position, and suturing to the sacral periosteum and rectal wall. Two patients had a small mucosal prolapse on physical examination that did not require surgery. One patient developed an early postoperative pelvic fluid collection—serous in quality, but with light growth of gram-positive cocci—that required laparoscopic drainage and resolved without graft explantation. No other complications occurred. Each patient has an intact repair at a median of 36 months of follow-up (range, 9–72 months), and no erosions, infections, or late strictures have occurred. FISI scores in 17 patients ranged from 0 to 33, with 8 patients reporting a score of 0. The median FISI score was 8 ± 12 indicating generally good bowel control. Subjective measures of continence are reported in Figures 4–7. Manometry studies in 9 patients indicated a range of results with resting pressures from 18 to 85 mm Hg, and squeeze pressures from 34 to 165 mm Hg, indicating a wide range of sphincter dysfunction, stemming from long-standing prolapse.
Figure 4. Patient-reported postoperative change in constipation.
Figure 5. Patient-reported postoperative change in incontinence.
Figure 6. Patient-reported postoperative FISI survey responses.
Figure 7. Patient-reported postoperative summary FISI scores.
DISCUSSION
Rectal prolapse is a common problem that can result in significant symptoms and risk if untreated. A portion of such cases progress to involve increasing pain, need for manual reduction, hemorrhage, and fecal incontinence, and a few require urgent surgical repair. Recurrence of rectal prolapse after surgical repair is not uncommon. Short-term recurrence rates of 27 and 3% for suture repair and mesh repair, respectively, were reported in reviews of cases of rectal prolapse repair.3,22–24 There is no consensus on a single best method for rectal prolapse repair.1,2,12 The cases presented in this series represent successful treatment of rectal prolapse with biologically derived graft reinforcement with UBM material, with satisfactory repairs and durability beyond 3 years.
Rectal wall mesh erosion requiring major surgery has been reported in both posterior and anterior rectopexy with synthetic mesh.4–11 Review of the existing literature regarding synthetic mesh erosion in rectopexy reports a median of 24 postoperative months until presentation of erosion, summarized in Table 2.4–11 Biologically derived materials have been used for pelvic organ prolapse repairs, without erosion.2,11 The series presented here would be expected to uncover any occurrence of erosion or graft complication both because of the 3-year follow-up and the nature of the UBM graft, which is fully biodegraded and replaced with host connective tissue within 2 years.25
Table 2. Summary of Literature Documenting Time to Presentation of Mesh Erosion
Study Number of Mesh Erosions Follow-up Period (months) Time to Mesh Erosion (months)
Borie9 7 24–120 Mean 31 (range, 3–62)
Adeyemo6 1 24 24
Mathew7 1 24 24
Tranchart10 6 87 Mean 50 (4–124)
Randall11 7 1–196 (median, 73) Not reported
Wong12 1 4–59 (median, 29) 1
Van den Esschert8 1 38 (mean) 1
Repair of pelvic organ prolapse with biologically derived mesh material appears to lower recurrence rates when compared to native tissue repair alone.26 Recent analysis of sacrocolpopexy with UBM reinforcement in primates demonstrates preservation of vaginal tissue quality and remodeling into robust fibrous connective tissue.27 Reoperations and repairs of recurrent rectal prolapses are challenging cases, with higher potential for complications. Mesh erosion or infection remain late complications in rectal prolapse repair, as well as hiatal hernia repair with synthetic mesh, including polytetrafluoroethylene.2,11,28 Synthetic mesh repair has been found to offer lower rates of recurrence in pelvic organ prolapse when compared to primary sutured repair, but has not been measured against biologically derived graft repairs.26 Improvement of continence after laparoscopic rectopexy is an endpoint that has been tested,1 but the performance of synthetic mesh versus biologic grafts have not been directly compared. In studies that have measured FISI score after laparoscopic rectopexy, postoperative scores are comparable to those obtained in this study.28,29 In addition, the durability of UBM has not been compared to that of synthetic mesh, so it is unknown whether a lower potential graft erosion risk and infection rate of the UBM would be realized and whether a corresponding higher rate of recurrence may result from the widespread use of UBM to reinforce rectal prolapse repairs. The UBM grafts handle favorably in the laparoscopic surgical environment and prove easier to suture than some grafts.
A rationale for using biologically derived grafts is the potentially lower rate of mesh erosion and mesh infection.2,4–11 Few complications are believed to occur with biologically derived mesh repairs, although one complication of a sterile abscess after hiatal hernia repair was reported, related to a non-UBM material requiring surgery to resolve.27 In addition, granulation tissue formation has been documented with biological graft use in pelvic organ prolapse repair.30 UBM devices include an intact epithelial basement membrane on one surface and a lamina propria layer on the opposite surface; contain multiple types of carbohydrates, collagens, proteins, and other components; and are gradually resorbed after implantation.16,18 UBM has been shown to facilitate a constructive remodeling process in numerous areas of the body that reduces scarring and facilitates the restoration of normal site-appropriate tissue.15,18,19 For these reasons, UBM was considered to be potentially advantageous in the reinforcement of the repair of large rectal prolapses. Although these features of UBM were likely contributing factors to the outcomes presented, larger studies directly comparing UBM to other synthetic and biologic materials are needed to further delineate the ideal reinforcement material for use rectal prolapse surgery.
CONCLUSIONS
At 3 years of follow-up after rectal prolapse repair with UBM reinforcement, there have been no recurrences requiring surgery, stenoses, pain syndromes, fistulization, or erosions. Handling characteristics of the UBM material suggest it will serve as an attractive candidate graft for anterior rectopexy repairs, as well as the posterior repairs described herein. Future investigation and long-term follow-up will determine which devices will offer the most cost-effective rectal prolapse repair reinforcement that reduces the risk of erosion, stenosis, pain, and graft infection while providing a durable repair.
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Drug Saf Case RepDrug Saf Case RepDrug Safety - Case Reports2199-11622198-977XSpringer International Publishing Cham 283577045010.1007/s40800-017-0050-3Case ReportHazardous Drug Diversion of Valproate from a General Practitioner to his Patient’s Dog Morice Pierre-Marie +33 06231065188morice-pm@chu-caen.fr 1Alexandre Joachim 234Cesbron Alexandre 2Sassier Marion 2Fedrizzi Sophie 23Humbert Xavier 251 0000 0004 0472 0160grid.411149.8Department of Pharmacy, CHU de Caen, Avenue de la Côte de Nacre, 14000 Caen, France 2 0000 0004 0472 0160grid.411149.8Department of Pharmacology, CHU de Caen, Avenue de la côte de nacre, 14000 Caen, France 3 0000 0001 2186 4076grid.412043.0EA 4650 Signalisation, électrophysiologie et imagerie des lésions d’ischémie-reperfusion myocardique, Université de Caen Basse-Normandie, 14032 Caen, France 4 0000 0004 0472 0160grid.411149.8Department of Cardiology, CHU de Caen, Avenue de la côte de nacre, 14000 Caen, France 5 Department of General Medicine, Medical school, 14032 Caen, France 30 3 2017 30 3 2017 12 2017 4 8© The Author(s) 2017
Open AccessThis article is distributed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International License (http://creativecommons.org/licenses/by-nc/4.0/), which permits any noncommercial use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.General practitioners are key stakeholders in good prescribing practices. More than half of patients have at least one unintended medication discrepancy upon hospital admission, some of which have the potential to cause severe discomfort or clinical deterioration. We report a case of a drug mistakenly administered to a 66-year-old man with cirrhosis and chronic alcoholism. Based on his regular prescription, he received 1 g/day of valproate during a hospitalization for cardiac valve surgery. This anticonvulsant was initially prescribed by his general practitioner for his epileptic dog and has been added to his own prescription to be covered by the French national health insurance. The aim of this article is to emphasize that general practitioners, physicians, and pharmacists have a major role to play in preventing the diversion of prescription drugs and limiting the risk of adverse drug events.
issue-copyright-statement© The Author(s) 2017
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Key Points
Prescription drug diversion is a serious public health problem that can lead to severe adverse consequences.
Medication reconciliation is a strategy requiring a complete review of all the medication taken by a patient during his/her hospitalization (admission, transfer, and discharge).
Physicians and pharmacists have a major role to play in preventing the diversion of prescription drugs and can be helped by medication reconciliation.
Introduction
The diversion of prescription drugs is a serious public health problem that can lead to severe adverse consequences such as overdose, admission to an emergency department, or death. The most affected drugs are opioid analgesics (hydrocodone, oxycodone), central nervous system depressants (alprazolam, diazepam), or stimulants (amphetamine) [1]. Lifestyle and prescription drug diversion can increase the risk of adverse drug events [2]. Because of a prescription given to the physician at admission, a 66-year-old man referred for cardiac valve surgery received oral valproate during his hospitalization. This drug was not initially prescribed for him but for his epileptic dog, in accordance with his general practitioner, to benefit from the reimbursement of the drug by the French national health insurance.
Case Report
A 66-year-old man hospitalized for cardiac valve surgery was admitted to the cardiology department for acute heart failure. His past medical history included alcoholic cirrhosis (Child A6) complicated by esophageal varices for 10 years, paroxysmal atrial fibrillation for 4 years, a mildly reduced kidney function (estimated glomerular filtration rate: 60–89 mL/min/1.73 m2) and 1 year prior, he had a mitral and aortic valve endocarditis caused by Staphylococcus epidermidis (successfully treated with intravenous vancomycin, gentamicin, and cloxacillin). His regular prescription medication at admission included isosorbide mononitrate (24 mg/day), valproate (1 g/day), inhaled beclomethasone (400 μg/day), furosemide (125 mg/day), and vitamin supplements. Blood biochemistry evaluations revealed the following: increases in the plasma potassium level to 6.1 mmol/L (reference range 3.6–4.8 mmol/L) and troponin I level to 0.09 ng/mL (reference range <0.04 ng/mL). Plasma creatinine level was 117.6 µmol/L (reference range 40–100 µmol/L) with a moderate renal impairment (clearance calculated by the Modification of Diet in Renal Disease equation: 54 mL/min/1.73 m2). Observations revealed a heart rate of 145 beats per minute, a blood pressure of 130/81 mmHg, and a normal oxygen saturation level of 98% with supplemental oxygen therapy (nasal cannula, 2 L/min). An electrocardiogram showed a heart rate of 154 beats per minute and atrial fibrillation. Auscultation revealed crepitant rales with murmurs, hepatojugular reflux, and edema in the lower extremities. A chest X-ray showed signs of cardiogenic pulmonary edema such as cardiomegaly, unilateral pleural effusion on the right side, and peripheral edema. The patient showed a good response to intravenous furosemide. After an improvement in the initial heart failure, the valve surgery was postponed because of a progressive increase in baseline liver enzymes level without fever. At day 3, the patient confessed to physicians an excessive drinking behavior (more than 1 L of beer every day) and a daily acetaminophen consumption (8 g every day): valproate and acetaminophen were stopped. Blood toxicological analysis collected on the fourth day showed a valproate concentration of 42.8 mg/L (therapeutic range 40–100 mg/L) followed by a gradual decrease, and an acetaminophen concentration under the lower limit of quantification (Fig. 1, day 4). Liver function analysis showed that the level of gamma-glutamyl transpeptidase was increased [peak plasma level on the fourth day at 386 U/L (reference range 5–55 U/L)], as well as the levels of alanine aminotransferase and aspartate aminotransferase [peak plasma levels on the fifth day at 3997 and 3452 U/L, respectively (reference range 5–45 U/L)]. The levels of total bilirubin and conjugated bilirubin were increased with a peak plasma level on the fifth day at 44 (reference range 1–17 µmol/L) and 16 µmol/L (reference range <3 µmol/L), respectively. Alkaline phosphatase, prothrombin time, and international normalized ratio were within normal limits. No ammonia, brain natriuretic peptide, glutathione level analysis, and liver biopsy were performed. Abdominal ultrasound showed a cirrhotic liver without bile duct obstruction. Hepatic veins were also normal. Viral infections were ruled out by blood examinations (viral hepatitis A, B, C, D, and E; human immunodeficiency and herpesviridae viruses). Intravenous administration of N-acetylcysteine started on day 5 (Fig. 1) and was associated with a decrease in liver enzymes that gradually returned to normal values and then were completely back to normal 1 month later. The patient admitted that valproate was not originally prescribed for him but for his dog to benefit from the reimbursement of this drug by the French national health insurances (veterinary drugs are indeed at the entire charge of the dog owner) and unfortunately the valproate was initiated upon his admission because it was noted as being one of the patient’s regular prescription drugs. Investigations revealed that this practice began 6 months previously.Fig. 1 Evolution of biological and toxicological parameters: blood alanine transaminase (ALT), aspartate transaminase (AST), gamma-glutamyltransferase (GGT), and valproate. Transaminase blood levels are represented on the left axis, the other parameters on the right axis. Markers indicate the beginning of valproate therapy (filled triangle) and valproate drug monitoring (shaded triangle)
Discussion
Drug diversion is an illegal distribution, an abuse of prescription drugs, or a use for purposes not intended by the prescriber. It manifests itself through various forms such as illegal Internet pharmacies, prescription forgery doctor shopping, or illicit prescribing by physicians [3]. The results from the 2012 National Survey on Drug Use and Health present the prescription drug abuse as a new epidemic and people are unaware that it causes harms, deaths, and economic costs [4]. Anabolic steroids, depressants, stimulants, hallucinogens, and opioids have a high potential for diversion [5]. In USA, the non-medical use of prescription drugs concerns 20% of the population (52 million people aged 12 years and older) [6]. To thwart drug diversion, physicians are helped by the development of new tools before prescribing, such as ‘prescription drug monitoring programs’, even if some practitioners disagree with the idea of using it (usability, dissatisfaction, erosion of physician autonomy) [7]. Community pharmacists also use educational supports and data-sharing projects for the management of patients suspected to be at high risk for drug diversion [8, 9]. In hospitals, pharmacists are responsible for the safe use of medications by reducing the risk of adverse events through medication reconciliation. They try to obtain the most accurate list of patients’ current medicines to ensure that medications being added, changed, or discontinued during hospitalization are cautiously evaluated. Hospital pharmacists significantly reduced the number of medication errors (including errors of high and extreme risk) [10, 11]. The aim is to reduce medication discrepancies and to prevent future events related to drug omissions (medication taken by the patient without any mention in the medical record), drug commissions (medication present in the medical record but not taken by the patient), drug duplications, dosing errors, and drug–drug interactions [12]. At admission, our patient received by error a non-indicated drug without having benefited from medication reconciliation. Since this event, we extended medication reconciliation to cardiology and nephrology care units. Unfortunately, we have no scientific data on the diversion of prescription drugs in France, but it seems not to be a common practice, unlike opioid diversion [13, 14]. Limiting the diversion of prescription drugs requires a coordinated approach between each member of the health system: pharmacists, physicians, and general practitioners, all supported by fraud control. This coordinated approach includes equal access to electronic medical records and the provision of additional continuing education to healthcare professionals.
Conclusion
This case report highlights the imperative need to strictly control indications of home drugs administered during hospitalization and the damaging consequences of the inappropriate use of reimbursement systems. A study found that 53.6% of patients had at least one unintended medication discrepancy upon admission, some of which had the potential to cause severe discomfort or clinical deterioration [15]. Moreover, these controls could limit adverse drug events, which represent a significant financial burden to healthcare with a US$887 million estimated cost in 2006 in USA [16]. General practitioners, physicians, and pharmacists play a major role in this context. They could be helped by the development of medical conciliation at patient hospital admission or discharge and by new healthcare delivery processes or tools [17, 18].
Acknowledgements
We thank Robert Taylor for his careful reading.
Compliance with Ethical Standards
Funding
No financial support was received for the preparation of this case report.
Conflict of interest
Pierre-Marie Morice, Joachim Alexandre, Alexandre Cesbron, Marion Sassier, Sophie Fedrizzi, and Xavier Humbert have no conflicts of interest directly relevant to the content of this case report.
Consent
Written informed consent was obtained from the patient for publication of this case report.
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Korean J Fam MedKorean J Fam MedKJFMKorean Journal of Family Medicine2005-64432092-6715The Korean Academy of Family Medicine 10.4082/kjfm.2017.38.2.102Case ReportA Diagnosis to Consider in an Adult Patient with Facial Features and Intellectual Disability: Williams Syndrome Doğan Özlem Akgün Şimşek Kiper Pelin Özlem Utine Gülen Eda Alikaşifoğlu Mehmet Boduroğlu Koray Division of Pediatric Genetics, Department of Pediatrics, Hacettepe University, Ankara, Turkey.Corresponding Author: Özlem Akgün Doğan. Tel: +90-3123051173, Fax: +90-3123051175, ozlem.akgun@hacettepe.edu.tr3 2017 22 3 2017 38 2 102 105 21 6 2016 21 9 2016 27 9 2016 Copyright © 2017 The Korean Academy of Family Medicine2017This is an open-access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0/) which permits unrestricted noncommercial use, distribution, and reproduction in any medium, provided the original work is properly cited.Williams syndrome (OMIM #194050) is a rare, well-recognized, multisystemic genetic condition affecting approximately 1/7,500 individuals. There are no marked regional differences in the incidence of Williams syndrome. The syndrome is caused by a hemizygous deletion of approximately 28 genes, including ELN on chromosome 7q11.2. Prenatal-onset growth retardation, distinct facial appearance, cardiovascular abnormalities, and unique hypersocial behavior are among the most common clinical features. Here, we report the case of a patient referred to us with distinct facial features and intellectual disability, who was diagnosed with Williams syndrome at the age of 37 years. Our aim is to increase awareness regarding the diagnostic features and complications of this recognizable syndrome among adult health care providers. Williams syndrome is usually diagnosed during infancy or childhood, but in the absence of classical findings, such as cardiovascular anomalies, hypercalcemia, and cognitive impairment, the diagnosis could be delayed. Due to the multisystemic and progressive nature of the syndrome, accurate diagnosis is critical for appropriate care and screening for the associated morbidities that may affect the patient's health and well-being.
Williams SyndromeAdultComplicationsManagementCase Reports
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INTRODUCTION
Williams syndrome (OMIM #194050) is a rare, well-documented, multisystem genetic condition affecting approximately 1/7,500 individuals. There are no marked regional differences in the prevalence of this disease.1) The syndrome is caused by the hemizygous deletion of approximately 28 genes, including ELN on chromosome 7q11.2.2) Prenatal and postnatal growth retardation, distinctive facial features, cardiovascular abnormalities, and a unique behavioral phenotype are among the most common clinical features of the syndrome.3) Periorbital fullness, a flat malar region, a full nasal tip, a wide mouth, and full lips and cheeks, which are together described as ‘elfin face,’ and stellate irises, especially in green- or blue-eyed individuals, are among the major facial features of patients with Williams syndrome. The facial features of patients with the syndrome do not differ with ethnic background. The exception is the presence of stellate irises, which are rarely reported in Asian patients.4) Supravalvular aortic stenosis is the most common cardiovascular system (CVS) abnormality, followed by supravalvular pulmonary stenosis and peripheral pulmonary stenosis. Mitral valve prolapse (MVP) and regurgitation may also be observed.3) Hypercalcemia is the most common endocrine problem, followed by hypothyroidism, impaired glucose tolerance, and osteopenia.35) Chronic abdominal pain, constipation, and diverticulosis attributed to elastin haploinsufficiency are also seen in patients with Williams syndrome.6) Moderate cognitive impairment and unique hypersocial behavioral features, such as diminished fear to approach strangers, elevated emphatic concern, reduced social fear, an increased attraction towards faces and eyes in social interactions, and a greater interest in contact with adults rather than younger peers are characteristic neurobehavioral features of the syndrome.6) Generalized anxiety disorder or specific phobias may also coexist with the above behavioral characteristics.7) Williams syndrome is usually diagnosed during infancy or childhood. However, in the absence of classical findings, the diagnosis may be challenging. Due to the multisystemic and progressive nature of the syndrome, accurate diagnosis is important for proper management and follow-up of the patients. Here, we report the case of a 37-year-old female patient referred to us with distinct facial features and intellectual disability. Our aim is to thoroughly describe the diagnostic features and management guidelines for Williams syndrome along with its associated complications.
CASE REPORT
A 37-year-old female patient was referred to Hacettepe University, Pediatric Genetics Department following complaints of atypical facial features. She was the second child of non-consanguineous healthy parents. She was born at term by spontaneous vaginal delivery with a birthweight of 1,500 g (lower than 3rd centile). Her birth length and head circumference were not recorded. The patient had delayed psychomotor development and began to walk and speak after the age of 3 years. She has been able to read and write after attending a rehabilitation program. She was evaluated for developmental delay, short stature, learning disability, recurrent upper respiratory system infections, and constipation in childhood, but no diagnosis was made. Laboratory work-up, including cranial imaging, echocardiography, and blood biochemistry were all normal except for subclinical hypothyroidism and osteoporosis. The patient had generalized anxiety disorder and hypochondriasis since her adolescence and her symptoms had deteriorated over time. She started to suffer from difficulty falling asleep, especially during the last five years. She was described as over-friendly by her family members. On her admission, a physical examination revealed a weight of 42 kg (lower than 3rd centile), a height of 145 cm (lower than 3rd centile), and a head circumference of 52 cm (−2 standard deviations). Among the facial features, a long face, a long neck accentuated by sloping shoulders, low-set ears, periorbital fullness, a short nose, a wide mouth, a small jaw, and malar flattening were noted (Figure 1). She was talkative and gregarious. The patient exhibited prolonged phases of staring into our faces and maintained eye contact throughout the physical examination. Based on these findings, the patient was clinically diagnosed with Williams syndrome. Fluorescence in situ hybridization analysis revealed 46,XX.ish del(7)(q11.2 q11.2) (ELN-), which confirmed the clinical diagnosis (Figure 2). Genetic counseling was provided to the family and a follow-up plan was created. An informed consent was obtained from the patient.
DISCUSSION
Williams syndrome is a multi-systemic disorder with a wide range of clinical symptoms and associated morbidities. This syndrome is usually diagnosed during infancy or early childhood. The symptoms in adulthood are not as suggestive as they are during childhood. In adulthood, patients usually present with mild intellectual disability and psychiatric disorders, including depression and anxiety disorder.7) The patients usually have subtle findings, but their unique behavioral patterns may be suggestive of Williams syndrome. Therefore, the awareness and shrewdness of the clinician may play a major role in the diagnosis of adult patients. During adulthood, due to the progressive and multi-systemic nature of the syndrome, patients suffer from problems concerning many organ systems and usually receive problem-specific care. With this kind of approach, patients cannot be evaluated in a holistic manner that would lead to the realization that each medical problem is an element of the underlying disorder. Therefore, the diagnosis of Williams syndrome may be challenging. The patient described here was not diagnosed during her infancy or childhood. She was repeatedly evaluated for developmental delay, short stature, and learning disability during childhood. However, no solid diagnosis was reached. She was referred to our clinic with the complaints of atypical facial features and intellectual disability. The quite unique behavioral phenotype was still not pointed out to us upon admission.
The clinical features of Williams syndrome may differ owing to the size of the deleted region.3) During the diagnosis, characteristic facial features and behavioral and cognitive phenotypes are the most helpful components. The distinctive facial appearance may change during adulthood. The fullness of the cheeks resolves, the face appears to be gaunt, and the patient has sloping shoulders and a long neck. Full lips and a wide mouth appear to be the only recognizable facial findings. Patients look older than they are and have premature graying of hair and dental malocclusion.6) In his case, the patient had full lips, a wide mouth, and periorbital fullness, which were key findings in the diagnosis.
The behavioral profile of Williams syndrome is as distinctive as the facial features associated with this condition. Patients have a unique behavioral pattern characterized by hypersociability, heightened empathy, and a desire for close relationships. The behavior of patients with Williams syndrome is characterized by approachability towards strangers and an increased attraction towards faces and eyes. These patients can easily start a conversation, but have difficulties in maintaining it. In contrast to their over-friendly phenotype, patients with Williams syndrome cannot form peer friendships due to difficulties in social adjustment and disinhibition. Social isolation especially manifests itself during adolescence and adulthood. The patient in this case was described by her family members as talkative, friendly, endearing, and gullible, especially during childhood. Her parents reported that she has a tendency to approach strangers and to put herself in danger. Despite her cheerful nature, the patient had generalized anxiety disorder and spells of panic beginning in adolescence. She was always nervous about being lonely and she had fear of illness and death. In Williams syndrome, specific phobias are mainly seen during childhood, while generalized anxiety disorder is the most frequent psychiatric diagnosis in adolescents and adults.7) Diagnosis of anxiety disorders tend to increase with age and significantly affects the quality of life of the patient. Therefore, a low threshold for psychiatric intervention is recommended.6) The patient in this case was diagnosed with generalized anxiety disorder and hypochondriasis during her follow-up.
The cognitive profile of Williams syndrome is also unique and varies from severe mental insufficiency to normal IQ. Patients have profound weaknesses in visuo-spatial constructive ability, but have strengths in language with excellent vocabularies.37) Adaptive functions of the individuals are also reported to be lower than normal. Developmental delay and mild intellectual disability were detected during childhood in the present patient. Regression in mental status was not detected, as expected. The patient lives with her family and takes care of her basic needs, but has never been employed.
Williams syndrome is a progressive disease with multi-systemic complications. The prevalence of these complications may increase with age. CVS, endocrine, and gastrointestinal system problems are frequently reported among adult patients.689) Supravalvular aortic stenosis is the major diagnostic cardiovascular system finding during childhood. However, in adulthood, mitral valve prolapse and regurgitation are the most commonly seen structural cardiac abnormalities. Although our patient did not have any symptoms related to CVS, her evaluation after the establishment of the diagnosis revealed MVP and mild hypertension. Annual CVS follow-ups were planned, as recommended. 36) Hypercalcemia, abnormal glucose intolerance, diabetes mellitus, hypothyroidism, and diminished bone density are the leading endocrine problems in patients with Williams syndrome.5) In our patient, subclinical hypothyroidism and osteoporosis were detected before her referral to our center. However, laboratory results related to hypercalcemia and hyperglycemia were all normal. Routine follow-ups for thyroid function tests every 3 years and annual dual-energy X-ray absorptiometry scans were planned. Gastrointestinal problems are frequently described in the literature, especially in adult patients.6) Chronic constipation, diverticulosis attributed to elastin haplosufficieny, and chronic abdominal pain are the leading problems.6) Our patient had chronic constipation, abdominal pain, and intermittent rectal bleeding. Colonoscopy and rectoscopy revealed multiple rectal fissures and dietary manipulation was recommended.68) Recurrent urinary tract infections, inguinal hernias, and bladder diverticula are common genitourinary system problems in adult patients, among which only bladder diverticulosis was detected in our patient.310)
In conclusion, Williams syndrome is a recognizable syndrome with distinct facial features, structural abnormalities, and unique a behavioral phenotype. However, when these findings are not recognized, diagnosis of the syndrome may be delayed. Diagnosis of Williams syndrome is critical for appropriate patient care and screening for high-risk problems that may affect the patient's health status and well-being. Therefore, the clinician's knowledge of this syndrome and skepticism are the key elements for proper diagnosis. We report this case to increase awareness of Williams syndrome among adult health care providers.
CONFLICT OF INTEREST: No potential conflict of interest relevant to this article was reported.
Figure 1 Front view of the patient. Note the long face, periorbital fullness, short nose, wide mouth, small jaw, and malar flattening.
Figure 2 Fluorescent in situ hybridization metaphase image with elastin gene probes. Please notice the absence of the red signal in one copy of chromosome 7, confirming the deletion of 7q11.23.
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1 Jones KL Smith DW The Williams elfin facies syndrome: a new perspective J Pediatr 1975 86 718 723 1133652
2 Korenberg JR Chen XN Hirota H Lai Z Bellugi U Burian D VI: Genome structure and cognitive map of Williams syndrome J Cogn Neurosci 2000 12 Suppl 1 89 107 10953236
3 Morris CA Pagon RA Adam MP Ardinger HH Bird TD Dolan CR Fong CT Williams syndrome Seattle (WA) GeneReviews 1993-2017
4 Yau EK Lo IF Lam ST Williams-Beuren syndrome in the Hong Kong Chinese population: retrospective study Hong Kong Med J 2004 10 22 27 14967851
5 Cambiaso P Orazi C Digilio MC Loche S Capolino R Tozzi A Thyroid morphology and subclinical hypothyroidism in children and adolescents with Williams syndrome J Pediatr 2007 150 62 65 17188616
6 Cherniske EM Carpenter TO Klaiman C Young E Bregman J Insogna K Multisystem study of 20 older adults with Williams syndrome Am J Med Genet A 2004 131 255 264 15534874
7 Ng R Jarvinen A Bellugi U Toward a deeper characterization of the social phenotype of Williams syndrome: the association between personality and social drive Res Dev Disabil 2014 35 1838 1849 24794322
8 Pober BR Morris CA Diagnosis and management of medical problems in adults with Williams-Beuren syndrome Am J Med Genet C Semin Med Genet 2007 145C 280 290 17639596
9 Wessel A Motz R Pankau R Bursch JH Arterial hypertension and blood pressure profile in patients with Williams-Beuren syndrome Z Kardiol 1997 86 251 257 9235796
10 Schulman SL Zderic S Kaplan P Increased prevalence of urinary symptoms and voiding dysfunction in Williams syndrome J Pediatr 1996 129 466 469 8804343
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Korean J Fam MedKorean J Fam MedKJFMKorean Journal of Family Medicine2005-64432092-6715The Korean Academy of Family Medicine 10.4082/kjfm.2017.38.2.106LetterValidity of Alcohol Use Disorder Identification Test: Methodological Issues Sabour Siamak 121 Safety Promotion and Injury Prevention Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran.2 Department of Clinical Epidemiology, Shahid Beheshti University of Medical Sciences, Tehran, Iran.Corresponding Author: Siamak Sabour. Tel: +98-21-22421814, Fax: +98-21-88015201, s.sabour@sbmu.ac.ir3 2017 22 3 2017 38 2 106 107 08 12 2016 30 12 2016 Copyright © 2017 The Korean Academy of Family Medicine2017This is an open-access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0/) which permits unrestricted noncommercial use, distribution, and reproduction in any medium, provided the original work is properly cited.Validity of Alcohol Use Disorder Identification Test-Korean revised version for screening alcohol use disorder according to Diagnostic and Statistical Manual of Mental Disorders, fifth edition criteria
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To the Editor
I was interested to read the paper by Chang et al.1) that was published in the November 2016 edition of the Korean Journal of Family Medicine. The purpose of the authors was to evaluate the validity of the Alcohol Use Disorder Identification Test-Korean revised version (AUDIT-KR) for screening alcohol use disorders (AUDs) in accordance with the Diagnostic and Statistical Manual of Mental Disorders, fifth edition (DSM-5) criteria.1) The study included 443 subjects who completed the AUDIT-KR. The subjects were divided into two groups, an AUD group and a non-AUD group, according to the DSM-5 criteria. Based on their report, the optimal cutoff score in the AUDIT-KR was 10 points for males (sensitivity, 81.9%; specificity, 81.3%; positive predictive value, 77.2%; and negative predictive value, 85.3%) and 5 points for females (sensitivity, 100.0%; specificity, 88.5%; positive predictive value, 52.6%; and negative predictive value, 100.0%).1)
Reported estimates are usually used to assess the validity of a single test instead of a questionnaire. To validate the revised version of any test, the suggestion is to focus on face and content validity, and probably on structure validity. However, considering the limitations of the mentioned estimates (positive predictive value depends on prevalence), why did the authors not use positive and negative likelihood ratios (LR+ and LR−), diagnostic accuracy, and odds ratio (ratio of true results to false results)?23456789) Finally, when the author reported area under the receiver-operating characteristic curve of the AUDIT-KR for identifying AUD, they actually reported the validity (accuracy and discrimination) of the model instead of the test. Therefore, it is crucial to not confuse a single test with a questionnaire or a diagnostic model because assessment of the validity of the mentioned concepts is completely different.23456789)
They concluded that the AUDIT-KR has high reliability and validity for identifying AUD in accordance with the DSM-5 criteria. Reliability (precision and calibration) is a different methodological issue from validity (accuracy and discrimination).2) Therefore, such conclusion may be misleading because of the inappropriate use of statistical tests to assess validity and confusing the concept of validity and reliability, and not differentiating between a single test with a questionnaire or diagnostic model.
CONFLICT OF INTEREST: No potential conflict of interest relevant to this article was reported.
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1 Chang JW Kim JS Jung JG Kim SS Yoon SJ Jang HS Validity of Alcohol Use Disorder Identification Test-Korean revised version for screening alcohol use disorder according to Diagnostic and Statistical Manual of Mental Disorders, fifth edition criteria Korean J Fam Med 2016 37 323 328 27900069
2 Szklo M Nieto FJ Epidemiology beyond the basics 2nd ed Sudbury (MA) Jones and Bartlett Publishers 2007
3 Sabour S Reliability of a new modified tear breakup time method: methodological and statistical issues Graefes Arch Clin Exp Ophthalmol 2016 254 595 596 26311259
4 Sabour S Ghassemi F The validity and reliability of a signal impact assessment tool: statistical issue to avoid misinterpretation Pharmacoepidemiol Drug Saf 2016 25 1215 1216 27696610
5 Sabour S Adherence to guidelines strongly improves reproducibility of brachial artery flow-mediated dilation: common mistakes and methodological issue Atherosclerosis 2016 251 490 491 27237073
6 Sabour S Farzaneh F Peymani P Evaluation of the sensitivity and reliability of primary rainbow trout hepatocyte vitellogenin expression as a screening assay for estrogen mimics: methodological issues Aquat Toxicol 2015 164 175 176 26004009
7 Sabour S Reliability of the ASA physical status scale in clinical practice: methodological issues Br J Anaesth 2015 114 162 163 25500399
8 Sabour S Ghassemi F Pediatric FOUR Score Coma Scale: interrater reliability and predictive validity-mistake and misinterpretation J Neurosci Nurs 2014 46 369 370 25365053
9 Sabour S Accuracy and reproducibility of dental measurements using different technologies, methodologic mistake Am J Orthod Dentofacial Orthop 2014 145 549 550
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Korean J Fam MedKorean J Fam MedKJFMKorean Journal of Family Medicine2005-64432092-6715The Korean Academy of Family Medicine 10.4082/kjfm.2017.38.2.108Author's ReplyAuthors' Reply to the Letter to the Editor “Validity of an Alcohol Use Disorder Identification Test: Methodological Issues” Chang Jung Wei Kim Jong Sung Jung Jin Gyu Kim Sung Soo Yoon Seok Joon Jang Hak Sun Department of Family Medicine, Research Institute for Medical Sciences, Chungnam National University School of Medicine, Daejeon, Korea.Corresponding Author: Jong Sung Kim. Tel: +82-42-280-8172, Fax: +82-42-280-7879, jskim@cnuh.co.kr3 2017 22 3 2017 38 2 108 108 09 2 2017 09 2 2017 Copyright © 2017 The Korean Academy of Family Medicine2017This is an open-access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0/) which permits unrestricted noncommercial use, distribution, and reproduction in any medium, provided the original work is properly cited.Validity of an Alcohol Use Disorder Identification Test: Methodological Issues
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First and foremost, in our study entitled, “Validity of Alcohol Use Disorder Identification Test-Korean revised version for screening alcohol use disorder according to Diagnostic and Statistical Manual of Mental Disorders, fifth edition criteria,” published in the November 2016 edition of the Korean Journal of Family Medicine, we did not conduct any analysis related to the reliability of the Alcohol Use Disorder Identification Test-Korean revised version (AUDIT-KR) and did not present any indicator of reliability in the body (Introduction, Methods, Results, and Discussion sections) of our manuscript. Nevertheless, the sentence, “The AUDIT-KR has high reliability and validity for identifying alcohol use disorder according to Diagnostic and Statistical Manual of Mental Disorders, fifth edition (DSM-5) criteria,” presented as a concluding statement in the Abstract includes the word ‘reliability.’ We admit that this is a serious clerical error on our part. As mentioned in the Letter, reliability (precision and calibration) is a different methodological issue from validity (accuracy and discrimination). We apologize to the Journal readers for making the mistake of using the word ‘reliability’ in the Abstract.
As specified in our study, the purpose of the research was to investigate the appropriate cutoff AUDIT-KR scores for screening alcohol use disorder with the newly released DSM-5 criteria and to evaluate sensitivity, specificity, and positive and negative predictive values. These indicators are included in ‘The validity of a single test’ section, as mentioned in the Letter. We think it is medically essential to evaluate the necessity of resetting screening standard scores for AUDIT-KR, which has been used as a screening tool for alcohol use disorder based on the DSM-5 criteria, in accordance with the changed diagnosis criteria. Evaluation of the content or structure validity of the questionnaire itself, as suggested in the Letter, is outside the scope of the purpose of our study.
We could have improved our study if we presented the figures mentioned in the Letter, such as positive and negative likelihood ratios, and odds ratio (ratio of true results to false results). However, we did not do so because of our insufficient statistical knowledge. We totally agree with the opinion expressed in the Letter that inappropriate use of the word ‘reliability’ may confuse the Journal readers about the concept of validity and reliability. We deeply appreciate the contributor of the Letter to the Editor for pointing out our major mistake and insufficient knowledge on the statistical concept including the use of area under the receiver operating characteristic curve.
CONFLICT OF INTEREST: No potential conflict of interest relevant to this article was reported.
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Korean J Fam MedKorean J Fam MedKJFMKorean Journal of Family Medicine2005-64432092-6715The Korean Academy of Family Medicine 10.4082/kjfm.2017.38.2.49EditorialShift Work and Health Problems Lee Jungun Department of Family Medicine, Wonkwang University Sanbon Hospital, Wonkwang University School of Medicine, Gunpo, Korea.3 2017 22 3 2017 38 2 49 50 Copyright © 2017 The Korean Academy of Family Medicine2017This is an open-access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0/) which permits unrestricted noncommercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
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Shift work is a reasonably common form of employment and recently, the number of shift workers has increased rapidly. A Korean working condition survey reported that the proportion of employees involved in shift work increased from 7.2% in 2006 to 10.9% in 2010.12)
Many diseases and health problems such as sleep disorders, cardiovascular diseases, reproductive issues, depressive mood, and increased mortality have been reported to be linked to shift work.3)
Several studies on shift work problems have been published in the Korean Journal of Family Medicine.456) Most of the subjects in those studies were hospital employees, and the number of the participants was relatively small.
On the topic of shift work, two studies about health behaviors and the prevalence of metabolic syndrome in Korean shift workers were reported.78) Both studies analyzed the Korean National Health and Nutritional Examination Survey (KNHANES) data, which provides national representative samples.
In a cross-sectional study of the Korean adult population, Bae et al.7) found that shift work was associated with negative health behaviors, such as smoking, alcohol consumption, and inadequate sleep, although the degree of association differed based on the participants' sex and age.
In another cross-sectional study by Yu et al.,8) an association between shift work and metabolic syndrome was demonstrated in young adults using data from the 2011–2012 KNHANES database. This study included 3,317 individuals ranging from 20 to 40 years of age. The prevalence of metabolic syndrome was 14.3% and 7.1% among male and female shift workers, respectively. After adjusting for confounding factors, shift work was associated with metabolic syndrome in female workers (odds ratio, 2.53; 95% confidence interval, 1.12 to 5.70). Few studies have evaluated the association between shift work and metabolic syndrome in younger adults, especially using data from the KNHANES database. This study is the first to evaluate the relationship between shift work and metabolic syndrome in young workers.
Interestingly, only female shift workers tended to have more unfavorable health problems and higher prevalence of metabolic syndrome than female day workers in the two studies considered here. They found that only the female shift workers aged ≥50 years were more likely to be current smokers, and partake in high-risk drinking.7) Because the smoking rate and the high-risk drinking rate were higher in all male worker age groups and in the younger age group for female workers, the influence of shift work on smoking and alcohol consumption in this particular group of women was weaker than expected. They also observed a higher proportion of those affected by inadequate sleep in the shift workers of both sexes, and the association between shift work and inadequate sleep was especially evident in men aged 20 to 39 years and in women aged ≥50 years.
Shift work was associated with metabolic syndrome in female workers but not in male workers.8) The authors explained this discrepancy by a high prevalence of menstrual irregularity and high obesity rates in shift workers. A prospective study reported that menstrual cycle irregularity might be a risk factor for metabolic abnormalities that could predispose individuals to the development of cardiovascular disease.9) Another cross-sectional survey reported that night shift work was associated with the development of obesity among night shift-working females.10)
However, as the KNHANES database does not include occupational qualitative data, they were not able to perform a detailed analysis of occupational qualitative data, such as the duration of shift work, intensity of work, and job categories. More prospective studies are needed to evaluate these potentially causal relationships.
Nonetheless, these studies imply the need to implement active strategies to reduce negative health behavior in shift workers to prevent adverse health outcomes.
CONFLICT OF INTEREST: No potential conflict of interest relevant to this article was reported.
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1 Wang JH Lee G Song JT Kwon J Choi H Jung-Choi K The association between shift work and bone mineral density: analysis of 2008-2009 Korean National Health and Nutrition Examination Survey Korean J Occup Environ Med 2012 24 274 286
2 2006 Occupational Safety and Health Research Institute Korean working condition survey report Ulsan Occupational Safety and Health Research Institute 2006
3 Rosa RR Colligan MJ National Institute for Occupational Safety and Health Plain language about shiftwork Cincinnati (OH) National Institute for Occupational Safety and Health 1997
4 Choi J Song YM Kim S Park YM Cho M A relationship between irritable bowel syndrome and physical activity in women nurses with shift work Korean J Fam Med 2010 31 529 539
5 Jung YJ Sa EJ Kim MN Lee DU Park KH Sung NJ Alteration of circadian diurnal rhythms of cardiovascular parameters by night shift work in 3 shift nurses J Korean Acad Fam Med 2007 28 187 194
6 Bae JH Jeong JH Combined effects of individual background, work shift and job stress on the prevalence of sleep problems in hospital employers J Korean Acad Fam Med 2003 24 232 244
7 Bae MJ Song YM Shin JY Choi BY Keum JH Lee EA The association between shift work and health behavior: findings from the Korean National Health and Nutrition Examination Survey Korean J Fam Med 2017 38 86 92
8 Yu KH Yi YH Kim YJ Cho BM Lee SY Lee JG Shift work is associated with metabolic syndrome in young female Korean workers Korean J Fam Med 2017 38 51 56
9 Solomon CG Hu FB Dunaif A Rich-Edwards JE Stampfer MJ Willett WC Menstrual cycle irregularity and risk for future cardiovascular disease J Clin Endocrinol Metab 2002 87 2013 2017 11994334
10 Peplonska B Bukowska A Sobala W Association of rotating night shift work with BMI and abdominal obesity among nurses and midwives PLoS One 2015 10 e0133761 26196859
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Korean J Fam MedKorean J Fam MedKJFMKorean Journal of Family Medicine2005-64432092-6715The Korean Academy of Family Medicine 10.4082/kjfm.2017.38.2.51Original ArticleShift Work Is Associated with Metabolic Syndrome in Young Female Korean Workers Yu Kyoung Hwa 1Yi Yu Hyeon 1Kim Yun Jin 1Cho Byung Mann 2Lee Sang Yeoup 34Lee Jeong Gyu 1Jeong Dong Wook 4Ji So Yeon 11 Department of Family Medicine, Medical Research Institute, Pusan National University Hospital, Busan, Korea.2 Department of Preventive and Occupational Medicine, Pusan National University School of Medicine, Yangsan, Korea.3 Department of Medical Education, Pusan National University School of Medicine, Yangsan, Korea.4 Department of Family Medicine, Research Institute for Convergence of Biomedical Science and Technology, Pusan National University Yangsan Hospital, Yangsan, Korea.Corresponding Author: Yu Hyeon Yi. Tel: +82-51-240-7834, Fax: +82-51-240-7843, eeugus@hanmail.net3 2017 22 3 2017 38 2 51 56 16 2 2016 10 5 2016 30 5 2016 Copyright © 2017 The Korean Academy of Family Medicine2017This is an open-access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0/) which permits unrestricted noncommercial use, distribution, and reproduction in any medium, provided the original work is properly cited.Background
Shift work is associated with health problems, including metabolic syndrome. This study investigated the association between shift work and metabolic syndrome in young workers.
Methods
A total of 3,317 subjects aged 20–40 years enrolled in the 2011–2012 Korean National Health and Nutrition Examination Survey were divided into shift and day workers. We conducted a cross-sectional study and calculated odds ratios using multivariate logistic regression analysis in order to examine the association between shift work and metabolic syndrome.
Results
The prevalence of metabolic syndrome was 14.3% and 7.1% among male and female shift workers, respectively. After adjusting for confounding factors, shift work was associated with metabolic syndrome in female workers (odds ratio, 2.53; 95% confidence interval, 1.12 to 5.70).
Conclusion
Shift work was associated with metabolic syndrome in young women. Timely efforts are necessary to manage metabolic syndrome in the workplace.
Metabolic SyndromeFemalePrevalenceOccupationsWorkplacePusan National University Hospitalhttp://dx.doi.org/10.13039/501100008130
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INTRODUCTION
Shift work is a common form of work worldwide; it is utilized in various areas of business and is a characteristic of modern society. Shift work is defined as a job schedule in which working hours are outside of the standard daytime hours.1) In Korea, the number of shift workers is steadily growing,2) and a recent survey reported that approximately 10.9% of employees are shift workers.3)
The prevalence of metabolic syndrome in the modern world is high and increasing continuously. Alterations in socio-environmental factors have contributed to this trend.4) Metabolic syndrome refers to a group of metabolic conditions, including increased blood pressure, high blood glucose level, abdominal obesity, high triglyceride level, and low high-density lipoprotein cholesterol levels5) that, combined, increase the risk of type 2 diabetes, heart diseases, and stroke.67) In Korea, the prevalence of metabolic syndrome in adults over 30 years of age is 32.9% and 31.8% in men and women, respectively.8)
Shift work has been identified as a cause of many health problems due to disruption of circadian rhythm.910) Prolonged interruption of the circadian rhythm may lead to an array of disorders, including insomnia, impaired glucose tolerance, obesity, and high blood pressure, which are important determinants of cardiovascular disease.1112) Because the majority of employees spend most of their time in the workplace, we believe that employers should develop prevention strategies and early interventions for metabolic syndrome in workplace settings.
Several studies have reported the association between shift work and risk of metabolic syndrome. A systematic review and meta-analysis13) of 10 original articles revealed that the association between metabolic syndrome and shift work varied among studies, and these studies showed discordant results. Consequently, the authors concluded that there was insufficient evidence on the relationship between shift work and the prevalence of metabolic syndrome. Moreover, few studies have evaluated the association between shift work and metabolic syndrome in younger adults, especially by using data from the Korean National Health and Nutrition Survey. Therefore, the current study examined the association between shift work and metabolic syndrome using a representative large-scale national database of workers.
METHODS
1. Data Source and Study Subjects
This study was based on data obtained from the fifth Korean National Health and Nutrition Survey (KNHANES) conducted in 2011 and 2012 by the Korean Ministry of Health and Welfare. The survey used a rolling sample design with stratified multistage cluster probability sampling of the South Korean population. The KNHANES was composed of three component surveys: a health interview survey, a health examination survey, and a nutritional survey. In 2011, the survey sample consisted of 3,840 households and 10,589 individuals (response rate 80.4%). In 2012, the survey sample consisted of 3,840 households and 10,069 individuals (response rate 80.0%). Individuals who had fasted for less than 8 hours and for whom hemoglobin A1c values were not available were excluded from the analysis. The present study included 3,317 individuals 20–40 years of age. The KNHANES was approved by the institutional review of board of the Korea Centers for Disease Control and Prevention. The approval code for 2011 was 2011-05CON-04-C and 2012 was 2012-07CON-01-2C. All study subjects provided written informed consent.
2. Assessment of Shift Work
Data concerning participants' work schedules were obtained from responses to the interview question, “Do you usually work during the day (between 6 am and 6 pm), or do you work at a different time?” There were eight possible answers: mainly daytime work, evening shift, night shift, regular day and night shift, 24-hour rotating shift, split shift, irregular shift, or other. Day workers were defined as subjects working mainly in the daytime, evening shift workers as subjects working between 2 pm to midnight, night shift workers as subjects working between 9 pm and 8 am the next day, and shift workers were defined as those subjects working in different time periods such as regular day and night rotating shifts, 24-hour rotating shifts, split shifts (working two shifts in one day), and irregular rotating shifts.
3. Assessment of Metabolic Syndrome
The metabolic syndrome prevention and treatment for Korean adults proposed by the Korean Academy of Family Medicine defined metabolic syndrome as the presence of at least three of the following criteria:14) (1) increased waist circumference (≥90 cm for men, ≥85 cm for women), (2) elevated triglyceride levels (≥150 mg/dL), (3) low high-density lipoprotein cholesterol levels (<40 mg/dL in men, <50 mg/dL in women), (4) elevated blood pressure (systolic ≥130 mm Hg and/or diastolic ≥85 mm Hg), and (5) impaired fasting glucose levels (≥100 mg/dL).
4. Assessment of Covariates
The baseline physical examinations and laboratory findings included measurement of weight, waist circumference, blood pressure, blood lipid profile (total cholesterol, triglyceride, high-density lipoprotein cholesterol, and low-density lipoprotein cholesterol), and fasting glucose level after an eight-hour fast. Waist circumference was measured at the narrowest point of the torso between the base of the rib cage and the top of the iliac crest. Systolic and diastolic blood pressure were measured from the right arm in triplicate with the participant in a seated position following at least five minutes of rest, using a mercury sphygmomanometer (Baumanometer; WA Baum Co., Copague, NY, USA). The second and the third blood pressure measurements were averaged for a final blood pressure measurement used for analysis. Blood samples collected from the antecubital veins following an eight-hour fast were immediately processed, refrigerated, and transported in cold storage units to the central laboratory (NeoDIN Medical Institute, Seoul, Korea) and analyzed within 24-hour after transportation. In addition, serum levels of glucose, total cholesterol, high-density lipoprotein cholesterol, and triglycerides were measured using an automated enzyme technique (Hitachi Automatic Analyzer 7600; Hitachi, Tokyo, Japan).
Components of health-related behavior were recorded through self-reported questionnaires including questions on smoking status, alcohol consumption, exercise, water intake, and average number of hours of sleep. Smoking status was divided into three categories: current smokers, ex-smokers, and never smokers. Heavy drinking was defined as drinking more than seven drinks for men and five drinks for women two or more times per week. Regular and adequate exercise was defined as at least 30 minutes of moderate-intensity physical activity at least three days per week or at least 20 minutes of vigorous-intensity physical activity at least three days per week. An average of six to eight hours of sleep was defined as optimal for health. Data regarding daily water consumption were obtained in the health interview survey. Body mass index was divided into four categories, with under 18.5 kg/m2 defined as underweight, 18.5 to 22.9 kg/m2 as normal, 23.0 to 24.9 kg/m2 as overweight, and 25.0 kg/m2 and above as obese. Additionally, data regarding menstrual cycle regularity (regular or irregular) and degree of menstrual irregularity (once in three months or missed three or more months in a row more than one time) were obtained among female subjects.
5. Statistical Analysis
The data were analyzed by complex-samples analysis. Survey sample weights15) was used and the complex survey design was accounted for in the estimation of variance. The survey sample weights were calculated by taking the reciprocal of the probabilities of selection (the primary sample units, household), adjusting for non-response (household, person), and a post-stratification factor to make the resulting survey estimates for age, sex, metropolitan area, or province category approximately equal to the total population of Korea in order to calculate unbiased cross-sectional national estimates for the general Korean population. To analyze samples in multiple years, sampling weights were averaged over the sampled years. Generalized linear regression analyses and χ2 tests were used to compare continuous and categorical variables, respectively, between the two groups. Continuous variables were expressed as means±standard error, and categorical variables were expressed as frequencies and percentages. In order to evaluate independent associations between shift work and metabolic syndrome, we used multivariate logistic regression analyses. Model 1 adjusted for age; model 2 adjusted for age, education level and family income; and model 3 adjusted for age, education level, family income, smoking status, alcohol consumption, exercise, average sleep duration, and average daily water intake. In women, menstrual cycle regularity was also adjusted for along with the other variables in model 3. The results were expressed as odds ratios (ORs) and 95% confidence intervals (95% CIs). Data analysis was performed using PASW SPSS Statistics for Windows ver. 18.0 (SPSS Inc., Chicago, IL, USA). Statistically significant differences were assumed for two-tailed P-values less than 0.05.
RESULTS
1. General Characteristics of the Study Population
Table 1 shows the subjects' baseline anthropometric measurements and the distribution of factors possibly related to metabolic syndrome. In both male and female subjects, shift workers were significantly younger than day workers (both P<0.001). There were no statistically significant differences in weight or waist circumference between day workers and shift workers in either sex.
There were also no statistically significant differences in total cholesterol, triglyceride, and fasting glucose levels in either sex. In female subjects, however, diastolic blood pressures were significantly higher in shift workers than those in day workers (P=0.04). The prevalence of menstrual cycle irregularity was also higher in female shift workers (16.8%) than in day workers (12.9%), and compared with day workers, shift workers had a significantly higher prevalence of a missed menstrual cycles over the previous three months (4.2% and 17.1%, respectively; P=0.015).
2. Health-Related Behaviors of the Study Population
Table 2 shows health-related behaviors among subjects. There were no statistically significant differences in rates of current cigarette smoking and heavy drinking, average sleep duration, and average water intake between day workers and shift workers in either sex. The proportions of female subjects who performed adequate exercise were higher among shift workers than that of day workers.
3. Association Between Shift Work and Metabolic Syndrome
Table 3 shows the ORs of metabolic syndrome according to type of work. Unadjusted, there were no statistically significant relationships between shift work and metabolic syndrome in either sex. After adjusting for age (model 1), the ORs for metabolic syndrome in female and male shift workers were 2.34 (95% CI, 1.11 to 4.94) and 1.06 (95% CI, 0.07 to 1.67), respectively. After adjusting for age, education level, and family income (model 2), the ORs in female and male shift workers were 2.25 (95% CI, 1.05 to 4.79) and 1.07 (95% CI, 0.07 to 1.70), respectively. After adjusting for age, education level, family income, education level, family income, smoking status, alcohol consumption, exercise, average sleep duration, and average water intake (model 3), the OR for metabolic syndrome in male shift workers was 0.93 (95% CI, 0.51 to 1.58). In female subjects, model 3 plus additional adjustment for menstrual cycle regularity resulted in an OR for metabolic syndrome of 2.53 (95% CI, 1.12 to 5.70). The association became statistically significant after adjusting for age, education level, family income, health-related behaviors, and menstrual cycle regularity. However, in male subjects, no significant association between shift work and metabolic syndrome was observed, even after adjustment.
DISCUSSION
This cross-sectional study was designed to determine the association between shift work and metabolic syndrome in young adults using data from the 2011–2012 KNHANES. Although previous studies1617) have examined the association between shift work and metabolic syndrome, they included small sample sizes or broad age ranges, and thus did not adequately evaluate the association between shift work and metabolic syndrome at young ages.
To our knowledge, the present study is the first to evaluate the relationship between shift work and metabolic syndrome in young workers. Several prospective studies have indicated that shift work may be an independent risk factor for metabolic syndrome. One such study found that rotating shift work increases the risk for developing metabolic syndrome over a period of six years.18) Another study of male and female nurses reported that the risk of developing metabolic syndrome was strongly associated with night-shift work over a four-year follow-up.19)
One possible explanation for the connection between shift work and metabolic syndrome is disruption of normal circadian rhythms.20) Circadian rhythms control several biological processes, including hormone secretion, body temperature, feeding, sleep-wake cycles, and metabolic homeostasis.21) Shift work promotes chronic misalignment between endogenous circadian oscillation and behavior cycles. This persistent circadian misalignment causes metabolic and cardiovascular events, including increased glucose and insulin levels, as well as increased mean arterial blood pressure and reduced sleep efficiency.22) Another possible explanation for this study finding could be socioeconomic status related to shift workers such as education level or family monthly income. In the present study, among male subjects with middle school or less education levels, the prevalence of metabolic syndrome was higher among shift workers compared with day workers; similarly, among female subjects with low-middle or lower family monthly income, the prevalence was higher among shift workers compared with day workers. Socioeconomic status has been reported to be associated with metabolic syndrome.2324) Education and family income may influence access and use of health services, and may affect health-related behaviors. In shift workers, lower levels of education or income may act as a significant barrier to access to health care and health publicity.
In the present study, shift work was associated with metabolic syndrome in female workers but not in male workers. In female workers, a high prevalence of menstrual irregularity was reported among shift workers and prevalence rates of obesity in shift workers was approximately 5% higher than that in day workers, although shift workers exercised regularly and received adequate sleep. One prospective study reported that menstrual cycle irregularity might be a risk factor for metabolic abnormalities that predispose individuals to the development of cardiovascular disease.25) Another cross-sectional survey reported that night shift work was associated with the development of obesity among night shift-working females.26) A possible explanation for this relationship is that many women with menstrual irregularities have polycystic ovary syndrome (PCOS), which has been associated with metabolic abnormalities that increase the risk of cardiovascular disease.27) Because the KNHANES data do not include manifestations of clinical and biochemical androgen excess, we cannot determine whether menstrual cycle irregularities were caused by PCOS in the present study. However, PCOS is the most common female endocrine hormonal disorder and a frequent cause of irregular menstrual cycles among young women.28) Many women with PCOS have features of metabolic syndrome such as central obesity,29) dyslipidemia,30) high blood glucose level,31) and high blood pressure.29) Therefore, menstrual cycle irregularity related to hormonal imbalances such as PCOS may be attributable to higher prevalence rates of obesity and metabolic syndrome in female shift workers. However, further prospective studies are required in order to investigate these associations.
This study has several strengths, including its large sample size and nationally representative sample of young working adults. However, it also has some limitations. First, because of its cross-sectional design, we were not able to establish a causal relationship between shift work and metabolic syndrome. Second, we did not collect information about eating habits and dietary patterns among the subjects and therefore could not assess their relationships with metabolic syndrome. Third, we did not perform a detailed analysis of occupational qualitative data, such as the duration of shift work, intensity of work, and job categories. The KNHANES does not include occupational qualitative data; therefore, we could not assess the effect of occupational qualitative variables that could be additional risk factors of metabolic syndrome. Further high-quality, prospective longitudinal studies are necessary to overcome these limitations.
ACKNOWLEDGMENTS
The findings and conclusions in this document are those of the authors and do not necessarily represent the views of the Occupational Safety and Health Research Institute, Korea Occupational Safety and Health Agency. This work was supported by a 2016 clinical research grant from Pusan National University Hospital.
CONFLICT OF INTEREST: No potential conflict of interest relevant to this article was reported.
Table 1 Characteristics of the study population
Values are presented as mean±standard error or frequency (%).
*Calculated using generalized linear regression analysis via complex sampling or χ2 test via complex sampling.
Table 2 Distribution of health-related behaviors in the study population
Values are presented as frequency % or mean±standard error.
*Calculated using generalized linear regression analysis via complex sampling or χ2 test via complex sampling. †Heavy drinking was defined as drinking more than 7 drinks for men and 5 drinks for women two or more times per week. ‡Exercise was defined as at least 30 minutes of moderate-intensity physical activity at least 3 days per week or at least 20 minutes of vigorous-intensity physical activity at least 3 days per week. §Six to eight hours of sleep was defined as optimal for health.
Table 3 Odds ratios of metabolic syndrome according to type of work
Values are presented as odds ratio (95% confidence interval). Odds ratios were calculated using multivariate logistic regression analyses via complex sampling. Model 1: adjusted for age; model 2: adjusted for age, education level, and family income; model 3: adjusted for age, education level, family income, smoking status, alcohol consumption, exercise, average sleep duration, and average water intake.
*Model 3 plus additional adjustment for menstrual cycle regularity in females.
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Korean J Fam MedKorean J Fam MedKJFMKorean Journal of Family Medicine2005-64432092-6715The Korean Academy of Family Medicine 10.4082/kjfm.2017.38.2.57Original ArticleMental Health of the People with Hearing Impairment in Korea: A Population-Based Cross-Sectional Study Shin Hyun-Young 12Hwang Hee-Jin 31 Department of Family Medicine, Myongji Hospital, Seonam University College of Medicine, Goyang, Korea.2 Department of Medicine, Catholic Kwandong University College of Medicine, Gangneung, Korea.3 Department of Family Medicine, Institute for Translational and Clinical Research, Catholic Kwandong University International St. Mary's Hospital, Incheon, Korea.Corresponding Author: Hee-Jin Hwang. Tel: +82-32-290-5114, Fax: +82-32-290-3879, ydsfm3624@naver.com3 2017 22 3 2017 38 2 57 63 27 4 2016 09 6 2016 09 6 2016 Copyright © 2017 The Korean Academy of Family Medicine2017This is an open-access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0/) which permits unrestricted noncommercial use, distribution, and reproduction in any medium, provided the original work is properly cited.Background
The prevalence of hearing impairment is increasing and an association between hearing impairment and mental health has been reported. Our study aimed to determine the association between hearing impairment and mental health in Korea.
Methods
This was a cross-sectional study of data from the Korean National Health and Nutrition Examination Survey 2010–2013, with a sample size of 18,563 individuals (6,395 with hearing impairment and 12,168 without hearing impairment), aged ≥20 years.
Results
The female group with hearing impairment tended to have a higher rate of stress (odds ratio [OR], 1.32; 95% confidence interval [CI], 1.11 to 1.56). The association between hearing impairment and depressive symptoms was higher in elderly males (OR, 1.60; 95% CI, 1.10 to 2.32), while the association of hearing impairment with suicide ideation was higher in elderly females (OR, 1.32; 95% CI, 1.00 to 1.75).
Conclusion
Elderly individuals with hearing impairment are easily susceptible to poor mental health status. Early targeted intervention to address mental health problems is recommended for people with hearing impairment.
DepressionHearingImpairmentMental HealthSuicideStress
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Introduction
Hearing impairment has become an important issue in public health worldwide,1) and the prevalence of hearing impairment is growing with the increase of elderly within the population.2) Moreover, the risk factors of hearing impairment such as diabetes, hypertension, smoking, and binge alcohol drinking are common to our modern environment. 34) Diminished communication, as a result of hearing impairment, can lead to social isolation, cognitive and functional decline, and dementia, decreasing the overall quality of life, which negatively affects mental health.567) Several previous studies have reported the association between hearing impairment and mental health, including increasing levels of depression and suicide ideation.89) However, there is lack of evidence concerning this relationship from a Korean representative sample, grouped by sex and age. Poor mental health is one of the most important issues in Korea, as Korea is the country with the highest suicide rate, but the second lowest worldwide rate of antidepressant consumption in 2013.10) Recently, the Korean government has made great efforts to create better conditions that may lead to an improvement in mental health status. Understanding the factors related to poor mental health might be helpful in deciding the most effective way to improve mental health in Korea. Therefore, our study aimed to determine the association between hearing impairment and mental health in Korea utilizing data obtained from the Korean National Health and Nutrition Examination Survey (KNHANES) 2010–2013.
Methods
1. Subjects
The study was based on data obtained for the KNHANES, performed by the Korean Ministry of Health and Welfare. KNHANES is a nationwide representative study, performed in six phases: phase I (1998), II (2001), III (2005), IV (2007–2009), V (2010–2012), and VI (2013–2014). This survey used a stratified, multistage probability sampling design for the selection of household units. In order to represent the entire Korean adult population, sampling weights were used to account for the complex sampling, which included stratification by district at the first step and stratification by sex and age at the second step. The survey consisted of the health interview survey, the health behavior survey, the nutrition survey, and the health examination survey. All data was obtained through self-administered questionnaires, with interviewers providing assistance to those who were unable to self-administer. Written informed consent to use data for further analyses was provided by all participants who were given the right to refuse to participate in accordance with the National Health Enhancement Act.
Cross-sectional analyses were performed on data obtained from 33,552 subjects of the KNHANES V and VI (2010–2013) who participated in the Health Interview Survey and the Health Examination Survey. Of these, a total of 18,563 individuals (8,041 male, 10,522 female), aged ≥20 years, with data from audiometric testing, were included in the final study analyses.
2. Definition of Hearing Impairment
Pure-tone audiometric testing was done using a SA 203 audiometer (Entomed, Malomo, Sweden). The test was conducted in a soundproof room located inside a mobile bus. All test processes, including instruction to the subjects, was performed by trained otolaryngologists. Furthermore, the result of air conduction thresholds was recorded using supra-auricular headphones. Automated testing was done through a modified Hughson-Westlake procedure, which used a single, pure tone, lasting 1 to 2 seconds. The threshold of the lowest level was defined when the participants responded to 50% of the pure tone. The reliability and validity of the automated hearing test was good, as compared to the manual test.1112) When the subjects heard the tone, they were instructed to push a button. The test frequencies were 0.5, 1, 2, 3, 4, and 6 kHz. The definition of hearing impairment was adopted from the definition utilized by the World Health Organization (speech frequency pure tone average) which was responding to frequencies ≥25 decibels, using the mean level of frequencies 0.5, 1, 2, and 4 kHz, in either the right or left ear.13)
3. Definition of Mental Health Status
To investigate mental health status, we examined levels of stress, presence of depressive symptoms, and response to suicide related statements or questions, adopted from the KNHANES V, such as “Describe the amount of your stress in your daily life”: (1) “I feel a lot of stress” or (2) “I feel stress a little,” and “Have you had depression symptoms for more than 2 weeks recently?”: (1) “yes” or (2) “no.” We also asked the question, “Have you had suicidal ideation in the past year?”: (1) “yes” or (2) “no.” Respondents answered the questions based on memory. Data of unanswered questions were treated as missing values.
4. Definition of Socioeconomic Variables, Health Risk Behaviors, and Diseases
Self-administered questionnaires from the health interview survey was used to gather information about socioeconomic factors (age, gender, education level, household monthly income, employed status, marital status), health-related factors (smoking status, alcohol drinking, physical activity, mental health status), diabetes, and hypertension. Education level was classified into ‘university or higher,’ ‘middle-high school,’ and ‘elementary school or lower.’ The household income variable was categorized into quartiles. Marital status was divided into ‘married,’ ‘separated,’ and ‘never.’ Occupation status was divided into ‘employed’ or ‘unemployed,’ which included students or homemakers. Smoking status was categorized as ‘current smoker’ or ‘past/non-smoker,’ which included ex-smokers and individuals that had never smoked. ‘Current smoker’ included those who currently smoke regularly or intermittently. ‘High-risk alcohol consumption’ was assessed using the question “How often do you binge drink?" and was categorized into two groups according to the frequency of binge drinking. Binge drinking was defined as ≥7 drinks for men and ≥5 drinks for women on one occasion. Individuals were classified as ‘non-binge drinker’ who reported binge drinking less than once per month and as ‘binge drinker’ who reported binge drinking once or more per month.1415) Physical inactivity was assessed with items based on the International Physical Activity Questionnaire (IPAQ) short form.16) ‘Insufficient physical activity’ was classified as none or some reported activity, but not enough to meet the categories 2 (moderate) or 3 (high) of physical activity levels in the IPAQ. Categories 2 (moderate) or 3 (high) of physical activity were included in ‘sufficient physical activity’ as a reference. More details concerning these criteria are described in IPAQ guidelines.17) Body weight and height were measured to the nearest 0.1 kg and 0.1 cm, respectively, while participants were wearing light indoor clothes, and without shoes. Body mass index (BMI) was calculated as the ratio of weight in kilograms to squared height in meters (kg/m2). Diabetes mellitus was defined by a fasting plasma glucose level ≥126 mg/dL, or the use of anti-diabetic medications. Hypertension was defined by a systolic blood pressure ≥140 mm Hg, a diastolic blood pressure ≥90 mm Hg, or through the use of anti-hypertensive medications.
5. Statistical Analysis
In the present study, all sampling and weight variables were stratified, and the IBM SPSS survey procedure ver. 20.0 (IBM Corp., Armonk, NY, USA) was used. Statistical analyses were performed to demonstrate descriptive statistics categorized by the presence of hearing impairment and by mental health. A Student t-test and chi-square test were performed to examine relationships among the multiple variables by presence of hearing impairment. Multiple logistic regression analyses were used to determine the level of association between mental health, and multiple variables, including sex and age. Odds ratios (ORs) were calculated after adjusting for age, sex, marital status, educational level, household income level, occupation, diabetes, hypertension, BMI, smoking, binge alcohol drinking, and physical activity, as these were the variables known to be associated not only with hearing impairment, but also with mental health status, both clinically and statistically. All statistical tests were two-sided and statistical significance was determined at a P-value <0.05.
Results
Basic characteristics are shown in Table 1. Among the 18,563 participants analyzed (6,395 hearing impairment and 12,168 non-hearing impairment), hearing impairment group was older, and demonstrated lower levels of current smokers, binge drinkers, physical activity, monthly household income, and employment. Furthermore, the rates of both diabetes and hypertension were higher in people with hearing impairment. Table 2 presented potential risk factors of mental health status. Perceived stress was found to be higher in females, current smokers, binge alcohol drinkers, individuals with more than university level education, individuals with a low-middle household income, as well as in single, and employed individuals. Conversely, perceived stress was found to be lower in old age, overweight, and individuals displaying sufficient physical activity. Depressive symptoms were higher in old age, females, low and lower-middle household income, separated individuals, as well as within those with diabetes and hypertension. Conversely, depressive symptoms were lower in individuals displaying sufficient physical activity, more than middle school educational level, and those that were employed. Regarding suicide ideation, similar associations with depressive symptoms were observed except a low prevalence in binge alcohol drinkers. Table 3 provides OR and 95% confidence interval (CI) for hearing impairment according to the mental health status by sex and age. In the oldest male group (≥60 years), hearing impairment was associated with depressive symptoms and suicide ideation (OR, 1.55; 95% CI, 1.08 to 2.21; OR, 1.53; 95% CI, 1.04 to 2.26, respectively). In the female group, hearing impairment was associated with perceived stress (OR, 1.30; 95% CI, 1.09 to 1.54); however, in subgroup analyses by age, no significant associations were observed. In the oldest female group, hearing impairment was associated with depressive symptom and suicide ideation, however the association with depressive symptom disappeared after adjustment in model 3 (OR, 1.25; 95% CI, 0.93 to 1.67; OR, 1.37; 95% CI, 1.04 to 1.80, respectively).
Discussion
This study indicated that the female group with hearing impairment tended to have higher rates of stress. In addition, an association of hearing impairment with depressive symptoms was observed. Furthermore, suicide ideation was found to be elevated in the old aged group and stronger in males than in females. These results are consistent with previous studies. For instance, a study conducted by Kobayashi et al.18) found a high association between Japanese individuals with hearing impairment and psychological distress in mental health (OR, 4.889; 95% CI, 4.267 to 5.601). Moreover, a separate study conducted by Armstrong et al.19) reported that individuals with hearing impairment displayed higher rates of depression (hearing impairment vs. non-hearing impairment: 19.3% vs. 14.6% in the CESD-5 [Center for Epidemiologic Studies–Depression 5] scale, 14.9% vs. 9.1% in the PHQ-9 [Patient Health Questionnaire-9] scale). Additionally, Gomaa et al.20)'s study showed that depression was more related to old age in males than in females, and that stress was more closely related with middle age in females than in males. Furthermore, a study conducted by Kim et al.21) showed that elderly with sensory impairment had 1.60–1.76 fold higher risk for suicide ideation. Finally, Turner et al.22) reported a significant gap between a hearing impairment group and a control group regarding depression and suicide ideation through a literature review.
The mechanism of the association between hearing impairment and poor mental health status has yet to be confirmed. There are however, several theories. First, disabled people tend to lack recognition of their mental problems, when compared to individuals without hearing impairment, so they do not recognize the need for treatment. Second, the socioeconomic environment of discrimination due to, or stigma towards, disability leads to depression. Third, people with hearing impairment have difficulties in accessing medical facilities. Therefore, proper diagnosis and management is difficult to provide. Finally, health professionals experience difficulties in communication with individuals that exhibit hearing impairment, so health professionals could overlook or misdiagnose a condition.1823)
Multivariate trials have been conducted to improve mental health in people with hearing impairment; however, more effort is needed to find an effective way to resolve the problem. Boi et al.24)'s study showed that the use of a hearing aid improved depressive symptoms in elderly patients. In contrast, Dawes et al.25)'s study reported no evidence of improved mental health or social isolation after using a hearing aid in people with hearing impairment. Evidence provided by Chen et al.26)'s study suggest that depressive thoughts and feelings in people with hearing impairment have decreased after the recovery of hearing impairment (OR, 0.14; 95% CI, 0.08 to 0.27). In the UK, as part of the government's efforts to respond to the needs of the deaf, the primary health care service has assumed an important role in breaking the physical and economical obstacles to treatment through increasing accessibility to health care.27)
Korea has the highest rate of suicide in the elderly, among Organization for Economic Cooperation and Development countries.10) From a report by the Ministry of Health and Welfare28) in Korea, the depression rate of the elderly population in Korea has increased 1.7 times over the past 5 years. Moreover, 11.2% of elderly in Korea have experienced suicidal ideation, mainly caused by health problems.29) Furthermore, some elderly individuals with hearing impairment might not be aware of their mental problems; hence, the prevalence of mental illness in the elderly could be underestimated. Therefore, not only treatment for hearing impairment, but also early screening for mental health would be an initial step to improve the mental health status in this population. Additionally, further efforts to break down the barriers between individuals with hearing impairment and medical professionals are absolutely necessary.30)
There are several limitations in our study. First, the cross-sectional nature of the survey precluded identification of causality. Second, as the people who were admitted to a hospital or nursing home were not included in the KNHANES, and as the severity of mental illness might be underestimated, it is possible that an overrepresentation of people with relatively mild hearing impairment or more severe mental health issues was included in the analysis. Third, the hearing test was conducted once in each participant. Thus, temporary hearing impairment was not differentiated in our study. Forth, our study used self-administered questionnaires for perceived stress, depressive symptoms, and suicide ideation, which may be subject to recall bias or concealment. Finally, there could be many hidden confounding factors that we could not consider. Despite these limitations, a major strength of this study is that it is based on a nationally representative population, with sampling weights that were applied to all analyses to maintain the level of representation of Korean adults in general.
In conclusion, the current study demonstrates that elderly with hearing impairment are easily susceptible to mental illness. Early intervention, including active screening and providing proper care, are recommended for resolving mental health problems in people with hearing impairment.
CONFLICT OF INTEREST: No potential conflict of interest relevant to this article was reported.
Table 1 Basic characteristics of hearing impairment and non-hearing impairment population in males and females
Values are presented as number (%) or mean±standard deviation.
*By Student t-test or chi-square test.
Table 2 Potential risk factors of mental health status using logistic regression analysis
Values are presented as odds ratio (95 confidence interval).
Table 3 Odds ratios of mental health status according to hearing impairment by sex and age group
Values are presented as odds ratio (95 confidence interval). Model 1: adjusted with age; model 2: adjusted with age, marital status, educational level, household income, and occupation; model 3: adjusted with age, marital status, educational level, household income, occupation, diabetes, hypertension, body mass index, smoking, alcohol binge drinker, and physical activity.
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1 Olusanya BO Neumann KJ Saunders JE The global burden of disabling hearing impairment: a call to action Bull World Health Organ 2014 92 367 373 24839326
2 Jun HJ Hwang SY Lee SH Lee JE Song JJ Chae S The prevalence of hearing loss in South Korea: data from a population-based study Laryngoscope 2015 125 690 694 25216153
3 Lee JS Choi HG Jang JH Sim S Hong SK Lee HJ Analysis of predisposing factors for hearing loss in adults J Korean Med Sci 2015 30 1175 1182 26240497
4 Hong JW Jeon JH Ku CR Noh JH Yoo HJ Kim DJ The prevalence and factors associated with hearing impairment in the Korean adults: the 2010-2012 Korea National Health and Nutrition Examination Survey (observational study) Medicine (Baltimore) 2015 94 e611 25761183
5 Weinstein BE Ventry IM Hearing impairment and social isolation in the elderly J Speech Hear Res 1982 25 593 599 7162161
6 Peracino A Hearing loss and dementia in the aging population Audiol Neurootol 2014 19 Suppl 1 6 9 25733359
7 Chia EM Wang JJ Rochtchina E Cumming RR Newall P Mitchell P Hearing impairment and health-related quality of life: the Blue Mountains Hearing Study Ear Hear 2007 28 187 195 17496670
8 Gopinath B Wang JJ Schneider J Burlutsky G Snowdon J McMahon CM Depressive symptoms in older adults with hearing impairments: the Blue Mountains Study J Am Geriatr Soc 2009 57 1306 1308 19570163
9 Qi B Li X Gao W Liu B The analysis of correlative factors on mental health of post-linguistic hearing loss adults Lin Chung Er Bi Yan Hou Tou Jing Wai Ke Za Zhi 2015 29 1598 1602 26790256
10 Organization for Economic Cooperation and Development Health at a glance 2015: OECD indicators. Paris: Organization for Economic Cooperation and Development Publishing 2015 cited 2016 May 11 Available from: http://www.keepeek.com/Digital-Asset-Management/oecd/social-issues-migration-health/health-at-a-glance-2015_health_glance-2015-en#page56
11 Swanepoel de W Mngemane S Molemong S Mkwanazi H Tutshini S Hearing assessment-reliability, accuracy, and efficiency of automated audiometry Telemed J E Health 2010 16 557 563 20575723
12 Mahomed F Swanepoel de W Eikelboom RH Soer M Validity of automated threshold audiometry: a systematic review and meta-analysis Ear Hear 2013 34 745 752 24165302
13 World Health Organization Prevention of blindness and deafness (PBD) program: prevention of deafness and hearing impaired grades of hearing impairment [Internet] Geneva World Health Organization 2010 cited 2016 Apr 20 Available from: http://www.who.int/pbd/deafness/hearing_impairment_grades/en/index.html
14 LaBrie JW Pedersen ER Tawalbeh S Classifying risky-drinking college students: another look at the two-week drinker-type categorization J Stud Alcohol Drugs 2007 68 86 90 17149521
15 Jeon GS Lee HY Associated factors of binge drinking and problem drinking among Korean men and women Korean J Health Educ Promot 2010 27 91 103
16 International Physical Activity Questionnaire Guidelines for data processing and analysis of the International Physical Activity Questionnaire (IPAQ): short and long forms [Internet] [place unknown] IPAQ Research Committee 2005 cited 2016 Apr 20 Available from: https://www.google.co.kr/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&ved=0ahUKEwiny9W2lbzMAhVl5aYKHVC-CjoQFggnMAE&url=https%3A%2F%2Fwww.researchgate.net%2Ffile.PostFileLoader.html%3Fid%3D56f92d66615e27d49a658031%26assetKey%3DAS%253A344600888791041%25401459170662924&usg=AFQjCNFu86dTe_OuPWO-puYIPhGnZbyAhw&sig2=m82M-YoYliqzXP4AJpB2_A&bvm=bv.121070826,d.dGY
17 Pate RR Pratt M Blair SN Haskell WL Macera CA Bouchard C Physical activity and public health: a recommendation from the Centers for Disease Control and Prevention and the American College of Sports Medicine JAMA 1995 273 402 407 7823386
18 Kobayashi Y Tamiya N Moriyama Y Nishi A Triple difficulties in Japanese women with hearing loss: marriage, smoking, and mental health issues PLoS One 2015 10 e0116648 25651532
19 Armstrong TW Surya S Elliott TR Brossart DF Burdine JN Depression and health-related quality of life among persons with sensory disabilities in a health professional shortage area Rehabil Psychol 2016 61 240 250 26891247
20 Gomaa MA Elmagd MH Elbadry MM Kader RM Depression, Anxiety and Stress Scale in patients with tinnitus and hearing loss Eur Arch Otorhinolaryngol 2014 271 2177 2184 24071860
21 Kim Y Kwak Y Kim JS The association between suicide ideation and sensory impairment among elderly Koreans Aging Ment Health 2015 19 658 665 25495960
22 Turner O Windfuhr K Kapur N Suicide in deaf populations: a literature review Ann Gen Psychiatry 2007 6 26 17922904
23 Okoro CA Dhingra SS Li C A triple play: psychological distress, physical comorbidities, and access and use of health services among U.S. adults with disabilities J Health Care Poor Underserved 2014 25 814 836 24858888
24 Boi R Racca L Cavallero A Carpaneto V Racca M Dall' Acqua F Hearing loss and depressive symptoms in elderly patients Geriatr Gerontol Int 2012 12 440 445 22212622
25 Dawes P Cruickshanks KJ Fischer ME Klein BE Klein R Nondahl DM Hearing-aid use and long-term health outcomes: hearing handicap, mental health, social engagement, cognitive function, physical health, and mortality Int J Audiol 2015 54 838 844 26140300
26 Chen J Liang J Ou J Cai W Mental health in adults with sudden sensorineural hearing loss: an assessment of depressive symptoms and its correlates J Psychosom Res 2013 75 72 74 23751242
27 Levine J Primary care for deaf people with mental health problems Br J Nurs 2014 23 459 463 24820809
28 Ministry of Health and Welfare Elderly people in depression increased by 1.7 times over the past five years [Internet] Sejong Ministry of Health and Welfare 2011 cited 2016 Apr 20 Available from: https://www.mohw.go.kr/front_new/al/sal0301vw.jsp?PAR_MENU_ID=04&MENU_ID=0403&CONT_SEQ=249839&page=9
29 Park JI Yang JC Han C Park TW Chung SK Suicidal ideation among Korean elderly: risk factors and population attributable fractions Psychiatry 2016 79 262 281 27880624
30 Noble W Preventing the psychosocial risks of hearing loss Aust Fam Physician 2009 38 591 593 19893780
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Korean J Fam MedKorean J Fam MedKJFMKorean Journal of Family Medicine2005-64432092-6715The Korean Academy of Family Medicine 10.4082/kjfm.2017.38.2.64Original ArticleAssociation Between the Awareness of Dyslipidemia and Health Behavior for Control of Lipid Levels Among Korean Adults with Dyslipidemia Cho In Young 1Park Hwa Yeon 2Lee Kiheon 2Bae Woo Kyung 3Jung Se Young 2Ju Hye Jin 1Song Jae Kyeong 1Han Jong Soo 31 Department of Family Medicine, Seoul National University Hospital, Seoul, Korea.2 Department of Family Medicine, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam, Korea.3 Department of Family Medicine, Health Promotion Center, Seoul National University Bundang Hospital, Seongnam, Korea.Corresponding Author: Jong Soo Han. Tel: +82-31-787-7807, Fax: +82-31-787-4834, flindt@snubh.org3 2017 22 3 2017 38 2 64 74 10 3 2016 30 3 2016 09 6 2016 Copyright © 2017 The Korean Academy of Family Medicine2017This is an open-access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0/) which permits unrestricted noncommercial use, distribution, and reproduction in any medium, provided the original work is properly cited.Background
Dyslipidemia is a major risk factor contributing to cardiovascular disease and its prevalence is steadily rising. Although screening tests are readily accessible, dyslipidemia remains undertreated. Evaluating health behavior patterns after diagnosis may help improve lifestyle interventions for the management of dyslipidemia.
Methods
Data from the fifth Korean National Health and Nutrition Examination Survey 2010–2012 were used. A total of 6,624 dyslipidemia patients over 20 years old were included according to National Cholesterol Education Program-Adult Treatment Panel III guidelines. Logistic regression analysis was completed using a weighted method to determine whether awareness of dyslipidemia was associated with health behavior. Health behavior was divided into two categories: behavioral factors (smoking, alcohol consumption, exercise) and nutritional factors (adequate intake of fiber, carbohydrate, fat, protein).
Results
There were no significant differences in health behavior among dyslipidemia patients according to awareness after adjustment for covariates, diabetes and hypertension. Awareness in women was associated with decreased smoking (odds ratio [OR], 0.55; 95% confidence interval [CI], 0.32 to 0.94), but when adjusted for diabetes and hypertension the result was not significant (OR, 0.61; 95% CI, 0.35 to 1.06). The same pattern applied to intake of carbohydrate in men (OR, 1.28; 95% CI, 0.99 to 1.67) and protein in women (OR, 1.22; 95% CI, 0.98 to 1.50). In subgroup analysis, awareness of dyslipidemia in men without hypertension or diabetes was associated with adequate intake of carbohydrate (OR, 1.70; 95% CI, 1.06 to 2.72).
Conclusion
Increasing awareness alone may not be enough to improve healthy behavior in patients with dyslipidemia. Efforts including patient education and counseling through a multi-team approach may be required.
DyslipidemiasHealth BehaviorSmokingExerciseAlcohol DrinkingAwareness
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Introduction
Cardiovascular disease (CVD) is one of the main causes of morbidity and mortality worldwide.1) According to 2013 death statistics in Korea, CVD was the second leading cause of death.2) Previous studies have declared that dyslipidemia is an important risk factor for CVD by contributing to the initiation and progression of atherosclerosis; therefore, its management is important for reducing the burden of CVD.3)
Meanwhile, the prevalence of dyslipidemia is steadily rising in Korea, and statistics published by the Korean Society of Lipidology and Atherosclerosis (KSLA) revealed that in 2013 57.6% of men and 38.3% of women, accounting for a total of 47.8% of people over 30 years of age (more than 16 million), had dyslipidemia. When the low-density lipoprotein cholesterol (LDLC) cutoff value was set to 100 mg/dL for diabetic patients, 9 out of every 10 diabetic adults had dyslipidemia. For patients with hypertension, 2 out of every 3 hypertensive adults were diagnosed with dyslipidemia.4)
The use of lipid-lowering medications such as statin and fibrate are important for the treatment of dyslipidemia, especially in high-risk patients. However, lifestyle interventions are also important for managing dyslipidemia and are considered initially after diagnosis, since dietary factors can influence lipid levels and regular exercise improves lipid profiles, while smoking has been known to have a detrimental effect.5) Villegas et al.6) reported that a combination of protective factors including normal body mass index (BMI), never smoking, light alcohol consumption, prudent diet and regular physical activity was associated with a significantly lower prevalence of dyslipidemia. Pharmacological therapy requires diagnosis by a doctor, and patients may be initially reluctant to take daily medication, making lifestyle interventions an attractive first choice for intervention. In fact, patients may be more compliant to behavioral modification and behavioral factors have the advantage that intervention for prevention of chronic diseases and lowering of cardiovascular risks can be emphasized at the population level. The Nurses' Health Study cohort was able to conclude that adherence to lifestyle guidelines for diet, exercise, and smoking was associated with a very low risk for coronary heart disease.7)
Previous reports have studied the prevalence, awareness, and treatment of dyslipidemia in Korea. Although awareness and treatment rates are slowly rising, their rates are still low (13.7% and 7.4% in 2010 compared to 6.1% and 1.9% in 2005, respectively).8) As for lifestyle interventions, there is a lack of studies examining adherence rates to clinical guidelines for lifestyle therapy in those with dyslipidemia, especially comparing those who are aware and those who are not aware of their diagnosis.
Lack of awareness about dyslipidemia may act as an additional barrier to adequate health behavior. However, whether awareness of dyslipidemia affects health behavior is not clear. In a study by Kitagawa et al., patients with high awareness of their health status showed a positive attitude towards diet and exercise as lipid-lowering treatment, and high adherence to drug therapy. However, subjects were limited to high-risk patients on prescription for pravastatin making it difficult to apply the results to the general population.9) Another study conducted in a Chinese province that analyzed dyslipidemia awareness and influencing factors demonstrated that awareness was associated with a lower odds ratio (OR) for drinking (OR=0.78) and physical activity (OR=0.714), and with higher OR for increased BMI (OR=1.547), age (increasing OR for older age groups), education (higher OR for higher level of education), and family history of dyslipidemia (OR=3.62).10) However, criteria for the factors mentioned were looser than clinical guidelines: drinking any kind of alcohol more than once a week, obesity as BMI ≥24 kg/m2, and exercising not less than once a week.
No other studies analyzing awareness of dyslipidemia and associated factors were found by the authors. Therefore, this study compared adherence to health behavior according to clinical guidelines between dyslipidemia subjects who were aware of their diagnosis and those who were not, with higher adherence expected in the awareness group.
Methods
1. Study Population
This study was performed using data from the fifth Korean National Health and Nutrition Survey 2010–2012 (KNHANES V). The KNHANES is a nationally representative study conducted regularly by the Korea Centers for Disease Control and Prevention to assess the health and nutritional status of non-institutionalized civilians in Korea. It uses a multi-stage probability sample design and trained interviewers to administer questionnaires to participants. The KNHANES V is based on data from 3,800 households in 576 randomly selected survey areas, with the number selected in proportion to the size of each area.11) For the selection of dyslipidemia patients, from a total of 25,334 individuals that participated in the KNHANES V, we excluded those aged <20 years (n=6,140), those who did not provide an answer for the assessment of awareness of dyslipidemia (n=1,518), whose lipid profiles were not assessed (n=959), and those who did not fast for over 9 hours (n=485). Those without available data for adequate physical activity, BMI, self-perceived health status, education, household income, and nutrient intake (n=2,115) were also excluded in the final analysis. The present study received an exemption from informed consent by the institutional review board committee of the Seoul National University Hospital because this study used public data provided by the KNHANES (IRB No. X-1602-333-903).
2. Measurement
Blood samples were collected from each participant the morning after fasting for at least 8 hours. Samples were processed, refrigerated immediately, and transported to the central laboratory to be analyzed within 24 hours after transportation. Total cholesterol (TC), high-density lipoprotein cholesterol (HDLC), triglycerides (TG), and fasting glucose levels were assessed using a Hitachi 7600 automatic chemistry analyzer (Hitachi, Tokyo, Japan). Direct LDLC measurements that were assessed by the automatic analyzer were used when available (participants eligible for sampling of heavy metal levels or with TG levels ≥200 mg/dL), and when unavailable, the Friedwald formula was used if the TG level was less than 400 mg/dL. Blood pressure was measured using a mercury sphygmomanometer (Baumanometer; WA Baum Co. Inc., Copiague, NY, USA) 3 times consecutively on the right arm with the participant in a seated position after at least 5 minutes of rest. The final blood pressure was obtained by averaging the second and third blood pressure measurements.12)
3. Definitions
Dyslipidemia was defined by levels of TC (≥240 mg/dL), HDLC (<40 mg/dL), TG (≥200 mg/dL), and LDLC (≥160 mg/dL, ≥130 mg/dL, or ≥100 mg/dL according to risk category) based on the National Cholesterol Education Program-Adult Treatment Panel III (NCEP-ATP III) guidelines,13) and whether participants answered that they were receiving treatment for dyslipidemia or taking medication to lower cholesterol levels.
Dyslipidemia awareness was assessed by the questions, “Have you been diagnosed with dyslipidemia by a doctor?" and “Are you currently suffering from dyslipidemia?" Patients who answered “yes" to either question were considered to be aware of their condition and assigned to the awareness group. Those who were diagnosed with dyslipidemia according to assessment of their lipid levels according to the NCEP-ATP III guidelines, but answered “no" to the aforementioned questions were included in the control group (unawareness group). Controlled dyslipidemia was also defined according to target levels set by NCEP-ATP III guidelines according to risk category.
Diabetes mellitus was identified based on fasting blood glucose levels (≥126 mg/dL) or use of insulin or oral hypoglycemic agents.14) Hypertension was diagnosed if subjects were taking medication for hypertension, or if average systolic blood pressure was over 140 mm Hg, or average diastolic blood pressure was over 90 mm Hg.15)
The study population was divided into two groups according to the definition of obesity (BMI ≥25 kg/m2) by the World Health Organization Regional Office for the Western Pacific Region and adopted by the Korean Society for the Study of Obesity.16)
4. Health Behavior for Control of Lipid Levels
Information related to health behavior that has been reported as being beneficial for the control of lipid levels was collected from the KNHANES V database, and these were divided into two groups: behavioral risk factors, and nutritional risk factors. KSLA 2015 and International Atherosclerosis Society (IAS) 2013 guidelines were used when applicable.
5. Behavioral Risk Factors
Information on current smoking status was collected through a self-reporting questionnaire, and those who answered that they smoked, or occasionally smoked, were considered current smokers, regardless of the amount. Smoking is a major cause of atherosclerotic cardiovascular disease (ASCVD), and the IAS states that high priority must be given to the prevention or cessation of smoking in lifestyle intervention for dyslipidemia.17)
Data on excessive alcohol consumption (≥3 standard drinks per occasion) were also collected through the self-reporting questionnaire. KSLA 2015 guidelines recommend limiting alcohol intake to 1–2 drinks per occasion.18)
Adequate physical activity was also assessed through answers to questionnaires and participants were considered to engage in adequate physical activity if they reported having carried out over 30 minutes of moderate intensity physical activity at least 5 days per week, or over 20 minutes of heavy intensity at least 3 per week. Epidemiological studies have shown that physical inactivity is associated with increased risk for ASCVD and regular physical activity has beneficial effects on lipoproteins.19) The IAS recommends approximately 30 minutes of daily moderate intensity activity, and specifies that the activity should be aerobic and carried out for a minimum of 5 days per week.17) For vigorous intensity activity, at least 20 minutes for 3 days a week was considered as adequate according to previous American Heart Association (AHA) guidelines.20)
6. Nutritional Factors
Nutritional factors were measured based on adherence to dietary recommendations that could be assessed using nutritional information provided by the KNHANES V. Therefore, adequate intake of macronutrients that was monitored by performing a 24-hour food recall and analyzed by the CAN-Pro software ver. 3.0 (Korean Nutrition Society, Seoul, Korea) was compared between the awareness groups. Adequate fiber intake (≥25 g/d), carbohydrate intake (<65% of total calories per day), fat intake (<30% of total calories per day), and protein intake (≥15% of total calories per day) were analyzed. The 2015 KSLA guidelines recommend limiting total daily carbohydrate intake and total fat intake to less than 30% of total calories per day and eating food rich in fiber for an intake of over 25 g of fiber per day.18) Diets high in cholesterol and saturated and trans-fat resulted in increased TG, LDLC, and total blood cholesterol. Previous studies have demonstrated that diets high in carbohydrate can increase TG levels, and dietary fiber can help lower blood cholesterol levels. For evaluation of protein and carbohydrate intake which was not specified in the 2015 KSLA guidelines, the American College of Sports Medicine recommendations were used where protein intake of 15% and carbohydrate intake of up to 60%–65% of total calories per day was prescribed for lifestyle management of dyslipidemia.21)
7. Statistical Analysis
All statistical analyses were performed using STATA statistical software ver. 14.0 (Stata Corp., College Station, TX, USA). All analyses were weighted to the Korean standard population from the years 2010 to 2012, reflecting the sampling method, response rate, and population structure of the KNHANES study.
Unpaired t-tests and chi-square tests were applied to continuous variables and categorical variables respectively in order to compare mean values and percentages of demographic and clinical characteristics between dyslipidemia patients according to awareness. Logistic regression was used to analyze which variables of health behavior were associated with awareness of dyslipidemia after adjusting for age. Afterwards, multivariable logistic regression was performed for each health behavior adjusting for age, education level, residential area (rural or urban), household income, self-perceived health status, marital status, and obesity (BMI ≥25 kg/m2). Adjusted OR, 95% confidence intervals (CI), and P-values were measured for the display of strength of each association. A P-value of <0.05 was considered significant.
Results
1. Baseline Characteristics of the Study Population
The characteristics of the study population are described in Table 1. Among the 6,624 dyslipidemia patients (14,415,037 when weighted), 17.1% were aware of their dyslipidemia status. Among the male population, 13.2% were aware of their diagnosis of dyslipidemia, while 22.6% of female dyslipidemia patients were aware of their diagnosis.
The mean age of the group who were aware of their condition was higher than that of the group that was unaware in both men and women. With respect to self-perceived health status, 14.3% of male patients in the unaware group responded that their health status was poor or very poor while 26.2% of those in the aware group gave the same response. Among men, 13.4% of the unaware and 17.5% of the aware received an elementary school or lower level of education, while 41.1% of women unaware of their dyslipidemia status received an elementary school or lower level of education and 52.2% of aware women reported receiving the same degree of education.
Awareness of dyslipidemia in both male and female patients was associated with a higher prevalence of diabetes mellitus and hypertension. Lipid profiles were also significantly favorable in aware groups with higher HDLC levels and lower TC, TG, and LDLC levels in both male and female dyslipidemia patients, although differences in the level of TG was not statistically significant in men.
2. Health Behavior for Control of Lipid Levels
Both men and women who were aware of their diagnosis of dyslipidemia had lower current smoking percentages (38.5% and 3.6%, respectively), and fewer aware women were likely to consume alcohol in excess (23.8% vs. 13.5%). When adjusted for other characteristics, female patients in the awareness group had a lower current smoking rate compared with those in the unaware group (OR, 0.55; 95% CI, 0.32 to 0.94), but when adjusted for the prevalence of diabetes and hypertension, the result was not statistically significant (OR, 0.61; 95% CI, 0.35 to 1.06). As can be observed in Table 2, there were no significant differences for alcohol consumption or adequate physical activity.
3. Adequate Macronutrient Intake
The only favorable nutritional factor observed in the aware groups by crude proportions was adequate intake of fat found in women aware of their diagnosis of dyslipidemia (93.7% vs. 96.0%). Although female patients aware of their diagnosis showed a higher OR for adequate protein intake (OR, 1.26; 95% CI, 1.00 to 1.58) when adjusted for covariates, the result was not statistically significant when additionally adjusted for the prevalence of diabetes and hypertension (OR, 1.22; 95% CI, 0.98 to 1.53). Men also showed a higher OR for adequate intake of carbohydrate (OR, 1.33; 95% CI, 1.04 to 1.72), but when adjusted for diabetes and hypertension the result was not significant (OR, 1.28; 95% CI, 0.99 to 1.67). There were no other statistically significant differences as shown in Table 3.
4. Subgroup Analysis according to Prevalence of Diabetes and Hypertension
In subgroup analysis of dyslipidemia patients without either hypertension or diabetes, men aware of their diagnosis of dyslipidemia had a higher OR for adequate carbohydrate intake (OR, 1.70; 95% CI, 1.06 to 2.72) after adjusting for other factors (Table 4).
In the subgroup analysis of dyslipidemia subjects with diabetes mellitus, there were no significant differences in health behavior according to awareness (Table 5). In the subgroup analysis of dyslipidemia subjects with hypertension, aware women showed a lower OR for smoking (OR, 0.46; 95% CI, 0.24 to 0.91) and a higher OR for adequate protein intake (OR, 1.37; 95% CI, 1.03 to 1.84), but when adjusted for covariates the results were no longer statistically significant (Table 6).
Discussion
This study suggests that there is minimal difference in health behavior between those aware and those unaware of their diagnosis of dyslipidemia among Korean adults over the age of 20 years. There was no statistically significant difference in health behavior and adequate macronutrient intake between the awareness groups after adjusting for demographic variables and the prevalence of diabetes and hypertension, perhaps because diabetes and hypertension are more important factors influencing adherence to health behavior. The only beneficial health behavior was found in the subgroup analysis, where adequate carbohydrate intake was observed in men with neither hypertension nor diabetes.
When analyzing crude proportions of adequate health behavior, rates of current smoking (38.5%) and excessive alcohol consumption (66.1%) in men aware of their diagnosis of dyslipidemia were higher than desirable and rates of adequate physical activity in both male and female dyslipidemia patients (19.8% in aware men and 15.9% in aware women) showed rates with ample room for improvement. Although rates of adequate fat intake were high in patients with dyslipidemia (93.4% in aware men and 96.0% in aware women), adequate intake of fiber in all subjects (2.7% in aware men and 1.2% in aware women), and carbohydrate in women (18.5% in aware women) were comparatively low. These results show that there is room for improvement in health behavior in the general population with dyslipidemia, even in those aware of their conditions. Unfortunately, awareness was not significantly associated with the health behaviors mentioned above after adjustment for covariates, implying that merely increasing awareness is not enough to promote health behavior. However, causality cannot be determined due to the cross-sectional design of this study.
Adequate control of lipid levels is important. A 1% reduction in total serum cholesterol levels can lead to a 2% to 3% reduction in risk of coronary disease,22) and a meta-analysis revealed that a 10% reduction in serum cholesterol was linked to a 13% to 14% reduction in CHD mortality and 8% to 10% reduction in total mortality.23) Although treatment of dyslipidemia with medication is important for adequate control of lipid levels, associated health behaviors and education for their implementation are also of importance and several guidelines (KSLA 2015, NCEP-ATP III, and IAS 2013 guidelines) actively recommend lifestyle intervention after diagnosis. In the study performed on dyslipidemia patients under pravastatin treatment in Japan, high awareness of health and positive attitude towards diet and exercise, and high adherence to drug therapy were related with favorable overall lipid levels.9)
Results published by the Korean Ministry of Health and Welfare on data from the KNHANES reveal that awareness rates of dyslipidemia are steadily rising (24.0% in 2005 to 59.0% in 2013); however, it is still low when compared to published results of awareness of other chronic diseases such as hypertension (65.3% in 2013) and diabetes (74.3% in 2013).24) The diagnosis and improved awareness of dyslipidemia are critical first steps for its adequate management; results in this study show that lipid profiles were more favorable for both men and women aware of their condition which may have been the result of lipid-lowering agents. Use of medication is inevitably higher in groups aware of their condition, as can be observed in the baseline characteristics of subjects for this study. Because there were no significant differences in adherence to health behavior recommended by clinical guidelines except for adequate carbohydrate intake in men with neither hypertension nor diabetes and rates of several types of health behavior showed plenty of room for improvement, adherence to health behaviors must be emphasized. Such change in behavior can be expected to have additional beneficial effects on lipid levels.
Although additional long-term studies are required to evaluate whether awareness of dyslipidemia can affect health behavior, results of this study suggest that awareness of dyslipidemia alone may not be enough to promote health behavior. One explanation can be that patients may be lacking in proper dyslipidemia education and instruction from their healthcare providers. This may also be the case for other chronic diseases. A study carried out on KNHANES 1998–2012 data analyzing adherence to dietary recommendations among Korean adults with diabetes mellitus concluded that Korean patients with diabetes have poor adherence to dietary recommendations and healthy lifestyle published by the Korean Diabetes Association regardless of awareness of diabetes.25) However, another study by Bardenheier et al.26) showed that both men and women aware of their diagnosis of diabetes differed in their daily intake of sugar and protein when compared to those unaware of their diabetic status. Although the difference in outcome may be due to the varied definitions of factors analyzed for association with awareness, the disparities between these studies may suggest that other factors exist apart from awareness influencing adherence to health behavior, and that the role of healthcare providers and practitioners may be crucial for lifestyle modification. Although well-established guidelines for chronic diseases call for lifestyle change as the initial line of therapy, it has been reported that physicians often do not follow these practices.27) Correct insights for medical professionals with respect to guidelines in the management of dyslipidemia, and monitoring and support systems may be required for better lifestyle behavior. Further studies are needed to provide insight on attitudes of both physicians and patients towards management of dyslipidemia through lifestyle interventions.
The development and establishment of public health policies to promote adequate behavior for the management of dyslipidemia may also be of help. A project carried out in Finland found that health promotion campaigns at a national level through various activities (such as media campaigns and health fares) can help increase population awareness on prevention of chronic diseases and prompt subjects to make beneficial lifestyle changes.28) Issues such as the perception of severity of risk factors and diseases, benefits of lifestyle modification, and calls to action should be addressed.29) As a further step, a multi-team approach and cooperation between healthcare providers and the community can provide fully integrated care leading to improved awareness and management of dyslipidemia.
In addition, interventions at community levels may also be helpful. Fritsch et al.30) reported that lipid-based interventions at the worksite (education and coaching on lifestyle and lipid values through classes and phone call interventions) can improve lifestyle behavior including exercise and diet, contribute to continuous health care, and lead to improved lipid values. After a 7-month intervention program, participants had an average of 5.2% reduction in TC.30) However, this was a short-term study performed at companies that were all members of a health insurer in North Carolina. Further large-scale studies carried out for a longer time intervals, or randomized controlled trials may be required to identify intervention methods that can effectively enhance health behavior in dyslipidemia patients.
This study has several strengths. First, to the knowledge of the authors, this is the first study to analyze adherence to health behavior recommended by clinical guidelines for the management of dyslipidemia according to patients' awareness. Furthermore, this study was conducted using data from a nationally representative sample of the Korean population, making the estimates of this study generalizable to the population of dyslipidemia patients in Korea. Additionally, KNHANES provides data collected through standardized laboratory and physical measurements. Finally, data was used from three consecutive years, providing a large sample size and powering the statistical ability to report associations.
This study also has several limitations. Because it is based on a cross-sectional design, it is difficult to assess any temporal relationship between awareness of dyslipidemia and health behavior and adequate macronutrient intake. Although daily intake of macronutrients was assessed for nutritional factors due to limited information and lack of data on total daily cholesterol intake or level of saturated or trans-fatty acids, evaluation of dietary patterns (such as AHA 2020 ideal healthy diet or Mediterranean diet) may be more appropriate due to inconclusive evidence of an independent effect of macronutrient intake on outcomes.31) Furthermore, it is unclear whether the status of each health behavior that the subjects reported would continue long term. There is also a need for the consideration of recall and social desirability bias, since data collected through self-reporting questionnaires was used for this study.
In summary, this is the first national-level study to analyze adherence to health behavior stipulated by clinical guidelines (by the KSLA and IAS) in dyslipidemia patients according to awareness. In this study, awareness was not associated with adequate health behavior except for adequate carbohydrate intake in men found in subgroup analysis of dyslipidemia subjects without hypertension or diabetes. Although further studies are required to assess any temporal relationship between awareness and health behavior, development of procedures including counseling and education by healthcare providers could be considered to guide patients according to guidelines for optimal control of lipid levels and prevention of CVD. Furthermore, large-scale prospective cohort studies that can help define reliable and practical plans for the enhancement of healthy behavior for the management of dyslipidemia are needed.
CONFLICT OF INTEREST: No potential conflict of interest relevant to this article was reported.
Table 1 Characteristics of dyslipidemia patients according to awareness of dyslipidemia
Values are presented as mean (95% confidence interval) for age and lipid levels and % (95% confidence interval) for the remaining variables. All data were weighted to the Korean standard population. Data and P-values were obtained from t-test for continuous variables and chi-square test for categorical variables. Diagnosis of DM: fasting blood glucose ≥126 mg/dL, use of insulin or oral hypoglycemic agents. Diagnosis of HTN: average systolic blood pressure ≥140 mm Hg or diastolic blood pressure ≥90 mm Hg, or taking medication for HTN.
DM, diabetes mellitus; HTN, hypertension; NA, not available.
*Less participants were available for analysis due to measurement methods (male: n=3,076, female: n=3,432).
Table 2 Behavioral risk factors according to awareness of dyslipidemia
Values are presented as % (95% confidence interval) or adjusted odds ratio (95% confidence interval), weighted to the Korean standard population. Crude proportions with P-values were obtained from chi-square tests, and logistic regression analysis was performed to examine the association between awareness of dyslipidemia and each health behavior with the adjustments specified. Model 1: adjusted for age; model 2: adjusted for age, obesity (BMI ≥25 kg/m2), self-perceived health status, education, residential area, and household income; model 3: adjusted for age, obesity (BMI ≥25 kg/m2), self-perceived health status, education, residential area, household income, prevalence of diabetes, and prevalence of hypertension.
BMI, body mass index.
*Statistically significant, P<0.05. †Excessive alcohol consumption: ≥3 standard drinks on ≥1 occasion in an average week. ‡Adequate physical activity: >150 minutes per week of moderate-intensity activity or >60 minutes per week of vigorous-intensity activity.
Table 3 Nutritional factors according to awareness of dyslipidemia
Values are presented as % (95% confidence interval) or adjusted odds ratio (95% confidence interval), weighted to the Korean standard population. Crude proportions with P-values were obtained from chi-square tests, and logistic regression analysis was performed to examine the association between awareness of dyslipidemia and each health behavior with the adjustments specified. Model 1: adjusted for age; model 2: adjusted for age, obesity (BMI ≥25 kg/m2), self-perceived health status, education, residential area, and household income; model 3: adjusted for age, obesity (BMI ≥25 kg/m2), self-perceived health status, education, residential area, household income, prevalence of diabetes, and prevalence of hypertension.
BMI, body mass index.
*Statistically significant, P<0.05. †Adequate intake of fiber: ≥25 g/d. ‡Adequate intake of carbohydrate: <65% of total calories per day. §Adequate intake of fat: <30% of total calories per day. ∥Adequate intake of protein: ≥15% of total calories per day.
Table 4 Subgroup analysis of health behavior according to awareness of dyslipidemia in subjects without hypertension or diabetes mellitus
Values are presented as % (95% confidence interval) or adjusted odds ratio (95% confidence interval), weighted to the Korean standard population. Crude proportions with P-values were obtained from chi-square tests, and logistic regression analysis was performed to examine the association between awareness of dyslipidemia and each health behavior with the adjustments specified. Model 1: adjusted for age; model 2: adjusted for age, obesity (body mass index ≥25 kg/m2), self-perceived health status, education, residential area, and household income.
*Statistically significant, P<0.05. †Excessive alcohol consumption: ≥3 standard drinks on ≥1 occasion in an average week. ‡Adequate physical activity: >150 minutes per week of moderate-intensity activity or >60 minutes per week of vigorous-intensity activity. §Adequate intake of fiber: ≥25 g/d. ∥Adequate intake of carbohydrate: <65% of total calories per day. ¶Adequate intake of fat: <30% of total calories per day. **Adequate intake of protein: ≥15% of total calories per day.
Table 5 Subgroup analysis of health behavior according to awareness of dyslipidemia in subjects with diabetes mellitus
Values are presented as % (confidence interval) or adjusted odds ratio (95% confidence interval), weighted to the Korean standard population. Crude proportions with P-values were obtained from chi-square tests, and logistic regression analysis was performed to examine the association between awareness of dyslipidemia and each health behavior with the adjustments specified. Model 1: adjusted for age; model 2: adjusted for age, obesity (BMI ≥25 kg/m2), self-perceived health status, education, residential area, and household income; model 3: adjusted for age, obesity (BMI ≥25 kg/m2), self-perceived health status, education, residential area, household income, and hypertension.
BMI, body mass index.
*Excessive alcohol consumption: ≥3 standard drinks on ≥1 occasion in an average week. †Adequate physical activity: >150 minutes per week of moderate-intensity activity or >60 minutes per week of vigorous-intensity activity. ‡Adequate intake of fiber: ≥25 g/d. §Adequate intake of carbohydrate: <65% of total calories per day. ∥Adequate intake of fat: <30% of total calories per day. ¶Adequate intake of protein: ≥15% of total calories per day.
Table 6 Subgroup analysis of health behavior according to awareness of dyslipidemia in subjects with hypertension
Values are presented as % (confidence interval) or adjusted odds ratio (95% confidence interval), weighted to the Korean standard population. Crude proportions with P-values were obtained from chi-square tests, and logistic regression analysis was performed to examine the association between awareness of dyslipidemia and each health behavior with the adjustments specified. Model 1: adjusted for age; model 2: adjusted for age and obesity (BMI ≥25 kg/m2), self-perceived health status, education, residential area, and household income; model 3: adjusted for age, obesity (BMI ≥25 kg/m2), self-perceived health status, education, residential area, household income, and diabetes mellitus.
BMI, body mass index.
*Statistically significant: P<0.05. †Excessive alcohol consumption: ≥3 standard drinks on ≥1 occasion in an average week. ‡Adequate physical activity: >150 minutes per week of moderate-intensity activity or >60 minutes per week of vigorous-intensity activity. §Adequate intake of fiber: ≥25 g/d. ∥Adequate intake of carbohydrate: <65% of total calories per day. ¶Adequate intake of fat: <30% of total calories per day. **Adequate intake of protein: ≥15% of total calories per day.
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Korean J Fam MedKorean J Fam MedKJFMKorean Journal of Family Medicine2005-64432092-6715The Korean Academy of Family Medicine 10.4082/kjfm.2017.38.2.75Original ArticleJoint Effect of Cigarette Smoking and Body Mass Index on White Blood Cell Count in Korean Adults Cho A-Ra Choi Won-Jun Kim Shin-Hye Shim Jae-Yong Lee Yong-Jae Department of Family Medicine, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul, Korea.Corresponding Author: Yong-Jae Lee. Tel: +82-2-2019-2631, Fax: +82-2-3462-8209, ukyjhome@yuhs.ac3 2017 22 3 2017 38 2 75 80 10 3 2016 08 6 2016 09 6 2016 Copyright © 2017 The Korean Academy of Family Medicine2017This is an open-access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0/) which permits unrestricted noncommercial use, distribution, and reproduction in any medium, provided the original work is properly cited.Background
White blood cell count is an independent risk factor for cardiovascular disease. Several lifestyle and metabolic factors such as cigarette smoking and obesity are known to be associated with an elevated white blood cell count. However, the joint effect of cigarette smoking and obesity on white blood cell count has not yet been fully described.
Methods
We explored the joint effect of cigarette smoking and obesity on white blood cell count using multiple logistic regression analyses after adjusting for confounding variables in a population-based, cross-sectional study of 416,065 Korean adults.
Results
Cigarette smoking and body mass index have a dose-response relationship with a higher white blood cell count, but no synergistic interaction is observed between them (men, P for interaction=0.797; women, P for interaction=0.311). Cigarette smoking and body mass index might have an additive combination effect on high white blood cell count. Obese male smokers were 2.36 times more likely and obese female smokers 2.35 times more likely to have a high white blood cell count when compared with normal body mass index non-smokers.
Conclusion
Cigarette smoking and body mass index are independently associated with an elevated white blood cell count in both men and women.
Leukocyte CountSmokingObesity
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Introduction
Several lifestyle factors, including cigarette smoking, alcohol intake, and lack of regular exercise, along with metabolic factors such as obesity, type 2 diabetes, hypertension, and dyslipidemia, are known to be associated with the risk of atherosclerotic cardiovascular disease (CVD). Although the pathogenesis of atherosclerosis and its relation to CVD remains unclear, increasing evidence suggests that arterial inflammation may play a key role in the process of atherosclerosis.12) A high white blood cell (WBC) count has been shown to be an independent predictor of cardiovascular events. Thus, early detection of an elevated WBC count may be important in predicting subsequent CVD morbidity and mortality.
The WBC count, widely evaluated in standard clinical practice, is a nonspecific marker of inflammation and may play an important role in the pathogenesis of arterial injury and the atherosclerotic process.1) Numerous studies in recent decades have revealed that lifestyle and metabolic risk factors are related to an elevated WBC count. For example, it has been demonstrated that current smokers have higher WBC counts than people who have never smoked.34) In addition, alcohol intake, 5) physical inactivity,6) body mass index (BMI),7) hypertension,8) type 2 diabetes,9) and dyslipidemia10) have been shown to be associated with an elevated WBC count.
The independent effects of lifestyle and metabolic factors on WBC count have been reported in numerous epidemiological studies.345678910) It may be more important whether there is an additive or synergistic effect of lifestyle and metabolic factors on inflammation causing cardiometabolic diseases. However, there has been limited exploration of the combined or interactive effect of lifestyle factors and metabolic factors on WBC count. Therefore, we investigated the possible interactive effects of cigarette smoking and BMI on WBC count in a large, population-based, cross-sectional cohort of 416,065 Koreans (105,505 men and 309,560 women), who underwent medical examination at the request of the National Health Insurance Corporation between 1993 and 1995.
Methods
1. Study Population
The Korean Cancer Prevention Study (KCPS) is a prospective cohort study designed to assess cancer risk factors by examining disease incidence, mortality, and hospital admissions. The KCPS cohort is primarily composed of government employees, teachers, and their dependents insured by the Korean Medical Insurance Corporation from 1992 through 1995. Subjects had at least one medical examination and completed a questionnaire during that period. The KCPS cohort includes 1,329,525 Koreans (846,907 men and 482,618 women) from 30 to 95 years of age who met the above selection criteria. This study did not include insured workers in its retrospective analysis because the WBC count of these individuals was not recorded during their medical examination. Therefore, the current analysis was limited to insured workers' family dependents in 1993 and 1995 (n=448,978). Then, 11,332 subjects whose WBC counts were less than 3,000 cells/mm3 or more than 11,000 cells/mm3 were also excluded from this analysis. To avoid confounding the association among smoking, BMI, and WBC count, 13,448 subjects who reported a history of cancer, CVD, respiratory disease, renal disease, and liver disease were also excluded. Additionally, 9,146 subjects with missing data on any covariate information or who had an extremely low BMI (<16.0 kg/m2) or short stature (<130 cm) were excluded from the study. After these exclusions, 416,065 participants (105,505 men and 309,560 women) between the ages of 30 and 95 years were included in the final analyses.
2. Data Collection
Medical examinations were performed according to a standardized procedure and were conducted by medical staff at local hospitals. In the 1993 and 1995 questionnaires, participants were asked about their smoking habits and other health-related behaviors. Body weight and height were measured with participants wearing light clothing without shoes to the nearest 0.1 kg and 0.1 cm, respectively. Participants were also asked if they were currently being treated for cancer or other diseases. If so, they were asked for the date of diagnosis. The completed questionnaires were reviewed by trained staff and then entered into a database. WBC count and serum levels of glucose and total cholesterol were measured under fasting conditions for routine clinical purposes. Each hospital had internal and external quality control procedures directed by the Korean Association of Laboratory Quality Control. Smoking exposure was categorized according to smoking status (non-smokers, ex-smokers, and current smokers) and the number of cigarettes per day among current smokers (1 to 9, 10 to 19, and 20 or more). BMI (kg/m2) was calculated as the ratio of weight (kg) and height (m2), and was divided into seven categories: <18.5, 18.5–19.9, 20.0–21.4, 21.5–22.9, 23.0–24.9, 25.0–26.9, and ≥27.0 kg/m2. The total daily alcohol consumption was expressed as the number of glasses per week in relation to Korea's most popular alcoholic beverage, ‘soju.’ One glass of soju contains about 12 g of ethanol. Alcohol consumption per day was categorized as follows: none (0 g), light (1–14.9 g), and moderate to heavy (15 g or more). Participants were also asked to report if they exercised regularly. WBC counts were quantified using automated blood cell counters (Beckman Coulter, Fullerton, CA, USA) in hospital laboratories. Fasting serum glucose and total cholesterol levels were analyzed using enzymatic methods with an automatic chemistry analyzer (Hitachi 7600-110; Hitachi, Tokyo, Japan). Impaired fasting glucose was defined as ≥100 fasting plasma glucose level <126 mg/dL. Diabetes was defined from self-reported history or when the fasting serum glucose level was ≥126 mg/dL. Pre-hypertension was defined as a systolic pressure of 120–139 mm Hg or a diastolic pressure of 80–89 mm Hg. Hypertension was defined from self-reported history or when systolic blood pressure was ≥140 mm Hg or diastolic blood pressure was ≥90 mm Hg. Hypercholesterolemia was defined when the fasting serum cholesterol level was ≥200 mg/dL. Because the study involved routinely collected medical data, it was not necessary to obtain individual participant consent.
3. Statistical Analysis
All statistical analyses were conducted in a gender-specific manner. Age- and BMI-adjusted means of the WBC count for each category of smoking exposure were calculated. The cutoff point for a high WBC count was determined as 7,500 cells/mm3, which corresponded to the 75th percentile.11) Multiple logistic regression analysis was used to compute odds ratios (ORs) and 95% confidence intervals (CIs) for high WBC counts, and the 95% CIs were examined according to the five categories of smoking exposure, seven categories of BMI, three categories of fasting serum glucose levels (normal, impaired fasting glucose, and type 2 diabetes), three categories of blood pressure (normal, pre-hypertension, and hypertension), and four categories of serum cholesterol levels (<160, 160–199, 200–239, and ≥240 mg/dL). Similarly, age-adjusted proportions of high WBC count per 1,000 persons were calculated and directly standardized to the age distribution of the Korean population in 1995. Further, we explored a possible interactive effect among smoking status, BMI, and gender-influenced metabolic risks on WBC count by using multiple logistic regression analysis. The potential interaction between cigarette smoking and BMI was tested by the multiplicative method. All analyses were conducted using SAS statistical software ver. 8.2 (SAS Institute Inc., Cary, NC, USA). All statistical tests were two-sided and statistical significance was determined at P-value <0.05.
Results
Table 1 shows the general characteristics of the study population, which consisted of about three times as many women as men. The mean BMI (kg/m2) of the study population was 22.7 for men and 24.0 for women. About 19.9% of men and 32.0% of women had a BMI ≥25.0 kg/m2, and 7.2% of men and 16.2% of women had a BMI ≥27.0 kg/m2. Both cigarette smoking and alcohol use were substantially more common in men than in women. Systolic blood pressure and levels of fasting serum glucose and total cholesterol were also higher in men than in women.
Figure 1 shows the age-adjusted means of WBC count (cells/mm3) according to BMI categories and smoking history. The mean WBC count was higher in ever-smokers among both men and women. Moreover, the mean WBC counts gradually increased with increasing BMI levels irrespective of smoking status in both men and women (all P for trends <0.001).
Table 2 shows the effects of lifestyle risks (smoking exposure, alcohol intake, and lack of regular exercise) and metabolic risks (high BMI, fasting serum glucose levels, blood pressure, and total cholesterol levels) on high WBC count. The findings show that smoking exposure had a strong, positive, dose-response tendency in men and women. Men and women who smoked 20 or more cigarettes per day were 2.34 times and 2.20 times more likely to have a high WBC count compared with non-smokers, respectively. Regular exercise had an inverse association with a high WBC count in both men and women, whereas light alcohol consumption (<15 g/d) had an inconsistent association with WBC count among both men and women. All four metabolic risks included in our analyses were also significantly associated with a high WBC count. The relative risks for high WBC count increased progressively with increasing BMI levels in both men and women. The association between high serum glucose levels and high WBC count was also significant in men and women. In addition, individuals with hypertension and pre-hypertension had significant associations with a high WBC count among both men and women. Moreover, the association between a high serum cholesterol level and high WBC count was also significant in both men and women.
We explored patterns of the joint effect of cigarette smoking and BMI on WBC count. Table 3 shows the OR estimates for the strata as defined by nine pairs of three categories of smoking status and three categories of BMI. The highest OR for a high WBC count was observed among current smokers who had a BMI ≥25.0 kg/m2. Obese male smokers were 2.36 times more likely and obese female smokers were 2.35 times more likely to have a high WBC count when compared with non-smokers with a normal BMI. Therefore, cigarette smoking and BMI seem to have an additive combined effect on high WBC count but no synergistic interaction (men, P for interaction=0.797; women, P for interaction=0.311).
Discussion
In this large, population-based cross-sectional study, cigarette smoking and BMI were found to be independently associated with WBC count with an additive combined effect. Among lifestyle factors, cigarette smoking had a prominent dose-response relationship with a high WBC count for both men and women. Our results also showed that the WBC count was high even in ex-smokers. This observed association is in agreement with most recent studies on this topic. Kawada12) reported that the WBC count was higher in smokers and ex-smokers than in non-smokers, and elevated WBC counts were maintained for several years after cessation of smoking. The mechanism underlying the smoking-induced increase in WBC count remains unclear. Chronic smoking stimulates the airway tract and may increase the WBC count.13) Light alcohol consumption (<15 g/d) decreased the OR for high WBC count in men, but not in women. Light alcohol consumption and casual drinking, but not binge or heavy alcohol consumption, has been reported to have significant beneficial effects on inflammatory markers.5) However, because our study did not distinguish between normal causal and binge drinking patterns, the association between alcohol consumption and WBC counts should be interpreted cautiously. The OR for high WBC counts was also significantly decreased in both men and women who exercised regularly. Regular exercise has a beneficial and favorable impact on abdominal fat accumulation, blood pressure, insulin sensitivity, dyslipidemia, and inflammatory markers.614151617) Since WBC count is strongly influenced by body fat, it may be equally plausible that lower WBC counts are an intermediate consequence of the effect of exercise on reduced body fat tissue.
Among metabolic factors, all four metabolic risks were found to be associated with high WBC counts among both men and women. The increase in WBC count according to BMI categories could also be explained by pro-inflammatory cytokines including interleukin-6 and tumor necrosis factor-α, which are expressed in adipose tissue and stimulate the WBC count.18) Hypertension and pre-hypertension were found to be significantly associated with the WBC count in both men and women. Recent studies have shown that the WBC count is associated with hypertension and high normal blood pressure.1920) Although, the role of WBCs in hypertension remains unclear, inflammation may contribute to increasing microvascular capillary resistance, reducing endothelial reactivity, and increasing catecholamine levels, which can increase blood pressure.212223)
Obesity is a state in which there is an increased storage of fatty acids in the form of triglycerides in adipose tissue.24) Continuous release of fatty acid from stored triglycerides causes dyslipidemia and drives gluconeogenesis in the liver.252627) Abdominal obesity, therefore, may be considered an important causal link between cardiovascular risk factors and high WBC count. In this regard, we explored the possible interactive effect of cigarette smoking as a representative of lifestyle factors and BMI as a representative of metabolic factors; however, we found that cigarette smoking and BMI were independently associated with WBC count, and no interaction was found between them in the current study. Therefore, cigarette smoking and BMI might have had an additive combined effect on high WBC count but no synergistic interaction.
Our study has several limitations. First, only one measurement of WBC count, from a baseline examination, was included in the analysis. Therefore, it was not possible to determine whether an acute, brief episode of inflammation or chronic inflammation was responsible for the correlation found in the current study. In addition, the effects of drugs such as aspirin or non-steroidal anti-inflammatory drugs, which can influence WBC count, were not fully adjusted for in the multiple logistic regression model. To minimize these errors, we excluded subjects with a WBC count exceeding 11,000 cells/mm3. However, it is important to note that although the WBC count varies daily, a single measurement has been shown to predict risk for death and specific diseases, including cancer and CVD.2829) Further, random misclassification because of biological variability may result in the underestimation of true associations, but this limitation does not explain our results. Second, information on the measurement of abdominal adiposity, such as waist circumference, was not available; consequently, we could not determine whether the increased WBC count associated with increased BMI depended on overall adiposity, specific adipose tissue, or a distribution pattern. Lastly, the study population, particularly the older population, might not be representative of the general population in Korea. However, since the sample size was quite large, we were able to investigate the relationship between a wide range of lifestyle and metabolic factors and WBC count. Because of these advantages, we found that each metabolic factor, even in the high normal range, was associated with WBC count.
In conclusion, our study demonstrated that cigarette smoking and BMI were independently associated with high WBC count, showing an additive combined effect.
CONFLICT OF INTEREST: No potential conflict of interest relevant to this article was reported.
Figure 1 Age-adjusted means of WBC count (cells/mm3) according to BMI category and smoking history. WBC, white blood cell; BMI, body mass index.
Table 1 Clinical characteristics of the study population
Values are presented as mean±standard deviation or %, unless otherwise indicated.
*Defined as systolic blood pressure 140 mm Hg and/or diastolic blood pressure ≥90mm Hg or a history of the disorder. †Defined as fasting serum glucose level ≥126 mg/dL or a history of the disorder.
Table 2 Age-adjusted proportion* per 1,000 persons and OR† for high WBC count‡ as a dependent variable and the associated factors as independent variables among men and women
OR, odds ratio; WBC, white blood cell; CI, confidence interval; NE, not estimated due to the small number of subjects; BMI, body mass index; FSG, fasting serum glucose; SBP, systolic blood pressure; DBP, diastolic blood pressure.
*The proportion per 1,000 persons is given, standardized according to the age distribution of Korea's national population in 1995. †OR and 95% CIs from multiple logistic regression analysis after adjusting for age, smoking exposure, alcohol intake, BMI, fasting plasma glucose levels, blood pressure, and total cholesterol levels. ‡The cutoff for high WBC count was determined as 7,500 cells/mm3, which corresponded to the 75th percentile. §Defined as ≥100 fasting plasma glucose level <126 mg/dL. ∥Defined as FSG level of at least 126 mg/dL or a history of the disorder. ¶Defined as ≥120 SBP <140 mm Hg and/or ≥80 DBP <90 mm Hg. **Defined as SBP ≥140 mm Hg, DBP ≥90 mm Hg, or a history of the disorder.
Table 3 Combined effect of cigarette smoking and BMI on high WBC count*
BMI, body mass index; WBC, white blood cell; OR, odds ratio; CI, confidence interval.
*The cutoff points of high WBC count were determined as 7,500 cells/mm3, which corresponded to the 75th percentile. †OR and 95% CI from multiple logistic regression analysis after adjusting for age, alcohol intake, regular exercise, fasting serum glucose, blood pressure, and total cholesterol.
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9 Nakanishi N Yoshida H Matsuo Y Suzuki K Tatara K White blood-cell count and the risk of impaired fasting glucose or type II diabetes in middle-aged Japanese men Diabetologia 2002 45 42 48 11845222
10 Lohsoonthorn V Dhanamun B Williams MA Prevalence of metabolic syndrome and its relationship to white blood cell count in a population of Thai men and women receiving routine health examinations Am J Hypertens 2006 19 339 345 16580566
11 Ishizaka N Ishizaka Y Toda E Nagai R Yamakado M Association between cigarette smoking, white blood cell count, and metabolic syndrome as defined by the Japanese criteria Intern Med 2007 46 1167 1170 17675764
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Korean J Fam MedKorean J Fam MedKJFMKorean Journal of Family Medicine2005-64432092-6715The Korean Academy of Family Medicine 10.4082/kjfm.2017.38.2.81Original ArticleAssociation Between Serum 25-Hydroxyvitamin D Levels and Dry Eye in Korean Adults: A Study Based on Korean National Health and Nutrition Examination Survey, 2010–2011 Kim Min Ji 1Hwang Hye Rim 12Kim Yun-Jin 12Lee Sang-Yeoup 234Lee Jeong-Gyu 12Jeong Dong-Wook 23Kim Yun Hee 11 Department of Family Medicine, Pusan National University Hospital, Busan, Korea.2 Department of Family Medicine, Pusan National University School of Medicine, Yangsan, Korea.3 Department of Family Medicine, Pusan National University Yangsan Hospital, Yangsan, Korea.4 Medical Education Unit, Medical Research Institute, Pusan National University School of Medicine, Yangsan, Korea.Corresponding Author: Hye Rim Hwang. Tel: +82-51-240-7834, Fax: +82-51-240-7843, hezera83@naver.com3 2017 22 3 2017 38 2 81 85 15 2 2016 13 6 2016 27 6 2016 Copyright © 2017 The Korean Academy of Family Medicine2017This is an open-access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0/) which permits unrestricted noncommercial use, distribution, and reproduction in any medium, provided the original work is properly cited.Background
Dry eye is a common disease. Many patients continue to experience residual symptoms despite optimal treatment. Thus, new treatment options are required. The purpose of this study was to evaluate the association between serum 25-hydroxyvitamin D [25(OH)D] levels and dry eye.
Methods
This study was performed using data from the fifth Korean National Health and Nutrition Examination Survey, which is a cross-sectional study of the Korean population that was conducted from 2010 to 2011. We included adults aged >19 years who underwent ophthalmologic interviews and examinations. We excluded subjects who had comorbid conditions (rheumatoid arthritis, thyroid disease, chronic kidney disease, or depression) that are associated with dry eye. The subjects were divided into normal and dry eye groups. The dry eye group consisted of those who had clinically diagnosed dry eye syndrome or symptoms. Multiple logistic regression analysis was conducted to determine the association between serum 25(OH)D levels and dry eye.
Results
In the univariate model, the 25(OH)D levels were lower in the dry eye group than in the normal group (P=0.01). A significant association was found between severe vitamin D deficiency (<10 ng/mL) and dry eye (P=0.04). However, after multivariate adjustment, the statistical significance of the association disappeared (P-values= 0.49, vitamin D insufficiency; P=0.33, vitamin D deficiency; P=0.18, severe vitamin D deficiency).
Conclusion
Severe vitamin D deficiency was associated with dry eye in an unadjusted model, but the association was not statistically significant after adjustment.
Vitamin D25-Hydroxyvitamin DDry Eye SyndromesDry Eye
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INTRODUCTION
Dry eye is one of the most common eye diseases. Patients with dry eye experience chronic inflammation of the lacrimal gland and ocular surface, with high concentrations of several inflammatory mediators including cytokines and T-lymphocytes.12) Tumor necrosis factor (TNF)-α, interleukin (IL)-1, and IL-6 were detected in the conjunctivae of dry eyes.34) As it can lead to ocular discomfort, visual disturbance, fatigue, and decreased quality of life, dry eye is a significant public health issue.56)
The current treatment of dry eye is limited to artificial tears, topical lubricant, plugging of the lacrimal punctae, or topical anti-inflammatory treatment; further, inflammation of the ocular surface of the dry eye has been reduced by using antioxidants and omega-3.78) However, a large number of patients complain of residual symptoms even after the use of optimal medical therapies; therefore, an alternative treatment option is required.9)
Vitamin D, a fat-soluble vitamin, is produced in the skin after exposure to sunlight or is obtained via dietary intake. Vitamin D is activated by hydroxylation in the kidneys and liver. Activated vitamin D regulates calcium metabolism, and cell proliferation and differentiation; in addition, it is involved in the regulation of immune function and bone metabolism, and in the mechanism of pathogenesis of various cancers, immune diseases, and vascular diseases.101112) The anti-inflammatory effect of activated vitamin D is achieved by blocking the activation of T-helper cells and cytotoxic T cells, and reducing the production of inflammatory mediators such as IL-2, IL-6, IL-8, and IL-12.11121314) Furthermore, vitamin D inhibits inflammatory factors such as C-reactive protein, TNF-α, IL-1, and IL-6, and induces IL-10 production.1516) Therefore, it has been suggested that vitamin D may be used for the treatment of dry eye. However, studies investigating the association between vitamin D and dry eye are lacking. Therefore, this study aimed to evaluate the association between serum 25-hydroxyvitamin D [25(OH)D] levels and dry eye in Korean adults on the basis of data from the Korea National Health and Nutrition Examination Survey (KNHANES).
METHODS
1. Study Population
This cross-sectional study analyzed data consolidated from the years 2010 and 2011 of the KNHANES (2010–2012). The KNHANES has been conducted by the South Korea Centers for Disease Control and Prevention since 1998 and consists of the following three parts: health examination, health interview, and nutrition surveys. The survey was reviewed and approved by the institutional review board of the South Korea Centers for Disease Control and Prevention (2010-02CON-21-C, 2011-02CON-06-C).
The KNHANES (2010–2011) included 15,932 adults aged >19 years who underwent ophthalmologic interviews and examinations. After excluding 6,583 subjects with comorbid conditions (rheumatoid arthritis, thyroid disease, chronic kidney disease, or depression) that are associated with dry eye, 9,349 subjects were included in the analyses.
Evaluation of age, sex, monthly house income level, residential area, educational level, employment status, body mass index (BMI), comorbidity (hypertension, diabetes, and dyslipidemia), cigarette smoking, binge drinking, regular physical activity, sleep duration, sun exposure time, and history of eye surgery were included in the analyses. Binge drinking was defined as drinking >7 drinks in one place at least once per month for men, or drinking >5 drinks in one place at least once per month for women. Regular physical activity was defined as 30 minutes of moderate physical activity performed more than three times in a week.
2. Measurement of Vitamin D Level
Serum 25(OH)D levels were commonly used to represent vitamin D status because 25(OH)D is the most stable component of various forms of vitamin D in vivo. Serum 25(OH)D levels were measured using radioimmunoassay (1470 WIZARD gamma-counter; PerkinElmer, Turku, Finland). The serum 25(OH)D levels ranged from 4 to 51 ng/mL, and the values were divided into 4 groups17181920) as follows: severe vitamin D deficiency (<10 ng/mL), vitamin D deficiency (10–19 ng/mL), vitamin D insufficiency (20–29 ng/mL), and vitamin D sufficiency (>30 ng/mL).
3. Criteria for Dry Eye
The subjects were divided into 2 groups as follows: normal and dry eye groups. The dry eye group included patients with clinically diagnosed dry eye syndrome or symptoms. The normal group included those who answered “no” to the following questions: “Have you ever been diagnosed with dry eye syndrome by a physician?” and “Have you ever felt the symptoms of dry eye?” Subjects who responded “yes” to at least one of the questions were included in the dry eye group.
4. Statistical Analyses
We used complex sample analysis according to the statistical guidelines of the Korea Centers for Disease Control and Prevention for analyzing raw data from the KNHANES. To determine differences between the groups, we used chi-square tests to compare categorical variables and linear regression analysis to analyze continuous variables. Multiple logistic regression analysis was used to evaluate the association between serum 25(OH)D level and dry eye, and the results were reported as odds ratios (ORs) and 95% confidence intervals (CIs). Statistical significance was set at a P-value <0.05. The PASW SPSS software ver. 18.0 (SPSS Inc., Chicago, IL, USA) was used for all the analyses.
RESULTS
1. Baseline Characteristics of the Study Subjects
Of the 9,349 subjects, 7,921 were assigned to the normal group (mean age, 44.34±0.33 years) and 1,428 were assigned to the dry eye group (mean age, 44.73±0.66 years). The sex distribution was significa different between the groups (normal group: 57.4% men and 42.6% women; dry eye group: 37.4% men and 62.6% women; P<0.001). The frequency of full-time paid work was significantly higher in the normal group (68.4%) than in the dry eye group (62%, P<0.001).
The distribution of BMI was significantly different between the groups (normal group: 4.4%, <18.5 kg/m2; 39.1%, 18.5–22.9 kg/m2; 56.6%, >23.0 kg/m2; dry eye group: 5.3%, <18.5 kg/m2; 43.6%, 18.5–22.9 kg/m2; 51.1%, >23 kg/m2; P=0.02).
The distribution of smoking status was significantly different between the groups (normal group: 30.3% current smokers, 21.3% exsmokers, and 48.4% non-smokers; dry eye group: 19.3% current smokers, 19.5% ex-smokers, and 63.2% non-smokers; P<0.001). The frequency of binge drinking was significantly higher in the normal group (51.8%) than in the dry eye group (43.4%, P<0.001). The distribution of subjects with sun exposure time was significantly different between the groups (normal group: 58.3%, <2 hours; 27.2%, 2–5 hours; 14.5%, >5 hours; dry eye group: 65.9%, <2 hours; 20.1%, 2–5 hours; 14.1%, >5 hours; P<0.001). The percentage of subjects with a history of eye surgery was significantly lower in the normal group (8.8%) than in the dry eye group (19.3%, P<0.001). Other general characteristics were not significantly different (Table 1).
2. Serum 25(OH)D Levels
The serum 25(OH)D level in the normal group (17.58±0.19 ng/mL) was significantly higher than that in the dry eye group (16.96±0.26 ng/mL, P=0.01). In addition, the serum 25(OH)D level of those aged 19–39 years was significantly higher in the normal group (16.48±0.19 ng/mL) than in the dry eye group (15.72±0.31 ng/mL, P=0.016). Serum 25(OH) D levels were not significantly different for any other variables (Table 2).
3. Relationship between Serum 25(OH)D Level and Dry Eye
OR was 1.20 (95% CI, 0.77 to 1.86) for vitamin D insufficiency, 1.453 (95% CI, 0.95 to 2.21) for vitamin D deficiency, and 1.61 (95% CI, 1.00 to 2.61) for severe vitamin D deficiency in the crude model. Compared with vitamin D sufficiency, a lower serum 25(OH)D level was associated with an increased risk of dry eye. In particular, severe vitamin D deficiency was significantly correlated with dry eye (OR, 161; 95% CI, 1.00 to 2.61) (Table 3).
OR was 1.24 (95% CI, 0.66 to 2.41) for vitamin D insufficiency, 1.30 (95% CI, 0.75 to 2.25) for vitamin D deficiency, and 1.42 (95% CI, 0.83 to 2.41) for severe vitamin D deficiency after adjusting for age, sex, BMI, smoking, binge drinking, sun exposure time, and history of eye surgery. Vitamin D level tended to decrease as the risk of a diagnosis or symptoms of dry eye increased. However, the OR for vitamin D status did not significantly correlate with dry eye (Table 3).
DISCUSSION
In the present study, in which the association between serum 25(OH) D level and dry eye was evaluated using data from the KNHANES-V (2010–2011), the serum 25(OH)D level (17.58±0.19 ng/mL) in the normal group was significantly higher than that in the dry eye group (16.96±0.26 ng/mL). This study was performed in Korean adults older than 19 years who had no medical history of disease associated with dry eye (rheumatoid arthritis, thyroid disease, chronic renal failure, and depression; P=0.01). In addition, the OR of severe vitamin D deficiency for dry eye was 1.61 (95% CI, 1.00 to 2.61; P=0.04). However, in the adjusted model, this was not statistically significant.
In a previous study, each 10-ng/mL increase in serum vitamin D levels, measured using 25(OH)D, was associated with a significant decrease in dry eye symptoms, as assessed using the 5-item dry eye questionnaire and tear film parameters.9) Moreover, in the same study, Mediterranean diet had an effect to improve systemic inflammatory markers.
Further, Yildirim et al.21) reported an association between dry eye and impaired tear function in patients with vitamin D deficiency, similar to the results of the present study, in which the dry eye group had significantly lower serum 25(OH)D levels than the normal group (P=0.01). Moreover, a lower serum 25(OH)D level was associated with an increased risk of dry eye, particularly in case of a severe vitamin D deficiency (OR, 1.61; 95% CI, 1.00 to 2.61; P=0.04). However, after adjusting for age, sex, BMI, smoking, binge drinking, sun exposure time, and history of eye surgery, this was not statistically significant (OR, 1.42; 95% CI, 0.84 to 2.40; P=0.18).
This study has certain limitations. First, dry eye syndrome and symptoms were diagnosed using only a simple questionnaire rather than subjective symptoms, physical examination results, or abnormal test results. Second, although seasonal variations can affect serum 25(OH)D levels, the present study did not consider this variable. Third, as this study was conducted only on Korean population, it is difficult to apply our findings in the general population. Fourth, our statistical methods or variables might have been different from those used in previously conducted studies. Finally, the cross-sectional nature of this study did not allow for evaluation of the cause-and-effect relationship between serum 25(OH)D level and dry eye. Our study results could have errors due to these limitations. Therefore, further prospective cohort studies are needed.
However, this study has several strengths. It is the first to investigate the association between vitamin D level and dry eye in adults using data from the KNHANES, which is a large-scale survey representing the Korean general population. Although our results showed that the serum 25(OH)D level in the normal group was significantly higher than that in the dry eye group, in Korean adults older than 19 years, we did not find a significant association between serum 25(OH)D level and dry eye after adjustment for various confounding factors.
In conclusion, the present study revealed no significant association between vitamin D level and dry eye. Further studies are needed to confirm the relationship.
CONFLICT OF INTEREST: No potential conflict of interest relevant to this article was reported.
Table 1 Baseline demographic characteristics of the participants according to the presence of dry eye syndrome or symptoms
Values are presented as mean±standard error or frequency (%).
*Analyzed using chi-square tests or independent t-tests. †Defined as drinking >7 drinks in one place at least once per month for men or drinking >5 drinks in one place at least once per month for women. ‡Defined as 30 minutes of moderate physical activity performed more than three times in weeks.
Table 2 Serum 25-hydroxyvitamin D [25(OH)D] levels according to dry eye status
Values are presented as mean±standard deviation.
*Analyzed by using independent chi-square tests. †Defined as drinking >7 drinks in one place at least once per month for men or drinking >5 drinks in one place at least once per month for women.
Table 3 Logistic regression analysis model for the unadjusted odds of dry eye based on vitamin D levels, and model 2 for the adjusted odds of dry eye based on vitamin D levels
Sufficient: ≥30 ng/mL; insufficient: 20–29 ng/mL; deficient: 10–19 ng/mL; severely deficient: <10 ng/mL.
OR, odds ratio; CI, confidence interval.
*Analyzed using logistic regression analysis and a complex sample; statistical significance set at P<0.05. †Adjusted for age, sex, body mass index, smoking, binge drinking, sun exposure time, and history of eye surgery.
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3 Massingale ML Li X Vallabhajosyula M Chen D Wei Y Asbell PA Analysis of inflammatory cytokines in the tears of dry eye patients Cornea 2009 28 1023 1027 19724208
4 Stern ME Gao J Schwalb TA Ngo M Tieu DD Chan CC Conjunctival T-cell subpopulations in Sjogren's and non-Sjogren's patients with dry eye Invest Ophthalmol Vis Sci 2002 43 2609 2614 12147592
5 Definition and Classification Subcommittee of the International Dry Eye WorkShop The definition and classification of dry eye disease: report of the Definition and Classification Subcommittee of the International Dry Eye WorkShop (2007) Ocul Surf 2007 5 75 92 17508116
6 Miljanovic B Dana R Sullivan DA Schaumberg DA Impact of dry eye syndrome on vision-related quality of life Am J Ophthalmol 2007 143 409 415 17317388
7 Drouault-Holowacz S Bieuvelet S Burckel A Rigal D Dubray C Lichon JL Antioxidants intake and dry eye syndrome: a crossover, placebo-controlled, randomized trial Eur J Ophthalmol 2009 19 337 342 19396775
8 Pinazo-Duran MD Galbis-Estrada C Pons-Vazquez S Cantu-Dibildox J Marco-Ramirez C Benitez-del-Castillo J Effects of a nutraceutical formulation based on the combination of antioxidants and ω-3 essential fatty acids in the expression of inflammation and immune response mediators in tears from patients with dry eye disorders Clin Interv Aging 2013 8 139 148 23430672
9 Galor A Gardener H Pouyeh B Feuer W Florez H Effect of a Mediterranean dietary pattern and vitamin D levels on Dry Eye syndrome Cornea 2014 33 437 441 24622300
10 Stumpf WE Vitamin D: soltriol the heliogenic steroid hormone: somatotrophic activator and modulator: discoveries from histochemical studies lead to new concepts Histochemistry 1988 89 209 219 3042715
11 Hewison M Vitamin D and the immune system: new perspectives on an old theme Endocrinol Metab Clin North Am 2010 39 365 379 20511058
12 Krishnan AV Feldman D Mechanisms of the anti-cancer and anti-inflammatory actions of vitamin D Annu Rev Pharmacol Toxicol 2011 51 311 336 20936945
13 Adams JS Hewison M Update in vitamin D J Clin Endocrinol Metab 2010 95 471 478 20133466
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15 Schwalfenberg GK A review of the critical role of vitamin D in the functioning of the immune system and the clinical implications of vitamin D deficiency Mol Nutr Food Res 2011 55 96 108 20824663
16 Liu LC Voors AA van Veldhuisen DJ van der Veer E Belonje AM Szymanski MK Vitamin D status and outcomes in heart failure patients Eur J Heart Fail 2011 13 619 625 21543375
17 Holick MF Vitamin D deficiency N Engl J Med 2007 357 266 281 17634462
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19 Dawson-Hughes B Heaney RP Holick MF Lips P Meunier PJ Vieth R Estimates of optimal vitamin D status Osteoporos Int 2005 16 713 716 15776217
20 Wang TJ Pencina MJ Booth SL Jacques PF Ingelsson E Lanier K Vitamin D deficiency and risk of cardiovascular disease Circulation 2008 117 503 511 18180395
21 Yildirim P Garip Y Karci AA Guler T Dry eye in vitamin D deficiency: more than an incidental association Int J Rheum Dis 2016 19 49 54 26269110
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Korean J Fam MedKorean J Fam MedKJFMKorean Journal of Family Medicine2005-64432092-6715The Korean Academy of Family Medicine 10.4082/kjfm.2017.38.2.86Original ArticleThe Association Between Shift Work and Health Behavior: Findings from the Korean National Health and Nutrition Examination Survey Bae Myung-Ji Song Yun-Mi Shin Jin-Young Choi Bo-Young Keum Jung-Hyun Lee Eun-Ae Department of Family Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.Corresponding Author: Yun-Mi Song. Tel: +82-2-3410-2442, Fax: +82-2-3410-0388, yunmisong@skku.edu3 2017 22 3 2017 38 2 86 92 04 3 2016 13 6 2016 27 6 2016 Copyright © 2017 The Korean Academy of Family Medicine2017This is an open-access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0/) which permits unrestricted noncommercial use, distribution, and reproduction in any medium, provided the original work is properly cited.Background
Shift workers are increasing worldwide, and various negative health effects of shift work have been reported. This study aimed to evaluate the relationship between shift work and health behavior.
Methods
This cross-sectional study included a total of 11,680 Korean adults (6,061 men and 5,619 women) aged ≥20 years old who participated in the Fifth Korean National Health and Nutrition Examination Survey, 2010–2012. Multiple logistic regression analysis was performed to evaluate the association between shift work and health behavior after adjusting for covariates.
Results
In men, shift work was associated with an increased risk of inadequate sleep (odds ratio [OR], 1.18; 95% confidence interval [CI], 1.00 to 1.40) compared to day work. In women, shift work was associated with an increased risk of smoking (OR, 1.73; 95% CI, 1.34 to 2.22) and inadequate sleep (OR, 1.24; 95% CI, 1.05 to 1.47) compared to day work. In an age-stratified subgroup analysis, female shift workers aged ≥50 years old demonstrated an increased risk of smoking (OR, 5.55; 95% CI, 3.60 to 8.55), alcohol consumption (OR, 2.22; 95% CI, 1.53 to 3.23), and inadequate sleep (OR, 1.50; 95% CI, 1.10 to 2.05) compared to female day workers.
Conclusion
Shift work is associated with worse health behavior, and this is most evident in women aged ≥50 years. Targeted strategies to reduce the negative health effects of shift work should be implemented, with consideration of shift workers' demographic characteristics.
Alcohol AbuseHealth BehaviorSleep DisordersSmokingWork Schedule ToleranceNational Research Foundation of Koreahttp://dx.doi.org/10.13039/5011000037252014R1A2A2A01002705
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INTRODUCTION
Over the last few decades, globally, the number of shift workers has increased rapidly to keep pace with the increasingly complex societal need for services and operations to be provided around the clock ceaselessly.1) The Korean working condition survey reported that the proportion of employees involved in shift work increased from 7.2% in 2006 to 10.9% in 2010. In this survey, the most commonly reported shift work type was the regular two-shift (38.6%), followed by regular three-shifts (23.9%), 24-hour rotating shift (14.0%), irregular two-shift (5.7%), fixed shift (5.5%), weekday split-shift (3.6%), irregular three-shift (2.9%), and others (5.8%).23)
Owing to the global increase in shift work, its effect on health has garnered increased attention from researchers, various health effects of shift work have been reported: sleep disorders; work-related injuries; digestive diseases such as gastritis and peptic ulcers; cerebrocardiovascular diseases such as ischemic stroke and ischemic heart disease; cancers such as breast cancer, prostate cancer, and colorectal cancer; reproductive outcomes such as preterm birth and natural miscarriage; behavioral disorders in children of shift workers; depressed mood; increased mortality; and low bone mineral density.2) Furthermore, in 2010, the International Agency for Research on Cancer classified night shift work as a probable human carcinogen.45)
Previous studies have suggested several mechanisms for the negative health effects associated with shift work.167) The circadian rhythm disruption in shift workers may cause a decrease in total sleep time and sleep efficiency, as well as an increase in insomnia prevalence and daytime sleepiness. Such disruptions influence the suprachiasmatic nucleus and endocrine functions, affecting the secretion of hormones such as growth hormone, thyroid hormone, corticosteroids, melatonin, serotonin, gastrin, and pepsinogen. These hormonal imbalances may then result in various clinical manifestations including gastric and duodenal ulcers.167) Another probable mechanism pertains to the shift workers' health behaviors. Owing to irregular working hours, shift workers are more likely to experience disturbances in their daily routine, and thus have difficulty in maintaining daily health behaviors, increasing their vulnerability to diseases.
Most observational and experimental studies evaluating the association between shift work and health behavior have been conducted in the United States or in the European countries68910111213141516) with few reports from Asian countries.1718) Up to now, several Korean studies have evaluated the relationship between smoking and working conditions or employment status such as permanent or temporary placements, overall work intensity, and weekly working hours.1920) however, these Korean studies not include shift workers.
Therefore, in the present study, we evaluated the association between shift work and health behaviors such as smoking, alcohol consumption, exercise, and the adequacy of sleep time in the Korean population using data from the fifth the Korean National Health and Nutrition Examination Survey.
METHODS
1. Study Subjects
This study utilized data from the fifth Korean National Health and Nutrition Examination Survey (KNHANES V). The survey was conducted on a nationwide basis, in a representative sample of South Korean adults and children, using a complex, multi-stage probability sample design, from 2010 to 2012. The survey consisted of three parts: the health interview survey, the health examination survey, and the nutrition survey health examination to examine the participants' health conditions, socio-demographic characteristics, health behaviors, and nutritional status.212223) Of the 25,534 participants of the KNHANES V, participants aged <20 years (6,140) and participants with missing information on working status, i.e., day work/shift work (13,465) were excluded. A total of 6,061 men and 5,619 women were included in this study for the final analysis.
2. Study Variables
There is no internationally standardized definition of shift work, and hence, previous studies show heterogeneity in the definitions used for analysis. We, therefore, classified the type of work based on the participant's answer to a relevant survey question: “Do you usually work in the daytime (6:00 am to 6:00 pm) or other times?” Participants who answered “I usually work in the daytime” were classified as day workers, while participants who reported as being involved in evening shift, night shifts, regular day-night shifts, 24-hour rotating shifts, split shifts, or irregular shifts were classified as shift workers.
Participants who had smoked ≥5 packs of cigarettes (100 units) during their lifetime and were currently smoking either every day or sometimes were classified as ‘current smokers,’ and the remaining were classified as ‘current nonsmokers.’
Alcohol consumption was assessed and classified based on drinking frequency and amount consumed at one time. Male participants who drank ≥7 cups and female participants who drank ≥5 cups more than once a month were categorized as ‘high-risk drinkers,’ and the remaining alcohol drinkers were categorized as ‘moderate drinkers.’
Vigorous exercise was defined as physical activity such as jogging, climbing, high-speed cycling or swimming, soccer, basketball, jump rope, squash, tennis (singles), or manual labor involving heavy loads, performed for a duration of >20 minutes and at a frequency of ≥3 times per week. Moderate exercise was defined as activities such as low-speed swimming, tennis (doubles), volleyball, badminton, table tennis, or manual labor involving light loads, for >30 minutes and ≥5 times per week. A low-intensity exercise was defined as walking or commuting for >30 minutes, ≥5 times per week. Participants who performed vigorous, moderate, or low-intensity exercises were included in the ‘physical activity’ group, while the remaining were included in the ‘physical inactivity’ group.
Previous studies have reported that a sleep duration of 7 to 8 hours per day is associated with lower risk of obesity, hypertension, diabetes, myocardial infarction, cerebral vascular accidents, and reduced risk of injuries and errors.7) With this reference value, we categorized participants into two sleep groups: adequate sleep group (7 to 8 hours per day), or inadequate sleep group (≤6 hours or ≥9 hours), respectively.
Based on the highest level of education attained, participants were categorized as ‘middle school or lower,’ ‘high school,’ and ‘college or higher.’
The monthly average family equivalent income was calculated as total household income divided by the square root of the number of household members. Participants' income level was classified based on monthly average family equivalent income quartiles: 1st (lowest), 2nd, 3rd, and 4th (highest).
Married participants who were currently living with spouse were classified into the ‘with spouse’ group while never married, divorced, or widowed participants were classified into the ‘without spouse’ group.
3. Statistical Analysis
All estimates were calculated based on the sampling weight provided in the KNHANES V. Continuous variables were compared between the day workers and shift workers using the Student t-test, while the categorical variables were compared using a chi-square test. The association between shift work and health behavior was evaluated using a logistic regression analysis. For multivariable adjusted analysis, age, average working hours per week, education level, income level, and marital status were included in the model as covariates. Analyses were performed for all participants, and also separately for men and women.
To assess the effect of age on the association between shift work and health behavior, we repeated the multiple logistic regression analyses based on three age strata (20–39, 40–49, and 50 years), with adjustment for average working hours per week, education level, income level, and marital status. The effect of age on the association between work type and health behavior was assessed by including an interaction term (work type*age group) in the multiple logistic regression models.
All analyses were conducted using IBM SPSS software for Windows ver. 21.0 (IBM Corp., Armonk, NY, USA). P-values <0.05 were considered statistically significant. The study protocol was approved by the Samsung Medical Center institutional review board (SMC 2015-12-112).
RESULTS
1. General Characteristics of the Study Participants
In total, 5,041 male day workers, 1,020 male shift workers, 4,709 female day workers, and 910 female shift workers were included in the study. Table 1 shows the weighted distribution of the study participants' general characteristics stratified by sex. On an average, in both sexes, the day workers were older compared to the shift workers (P<0.001). The distribution of average sleep hours per day was significantly different in men (P=0.010) and women (P=0.009), and both the longest (≥9 hours) and the shortest (≤6 hours) sleep time were more prevalent among shift workers than among day workers. The distribution of average work time per week differed between the shift workers and day workers of both sexes (P<0.001), and both the longest (>60 hours) and shortest (<40 hours) work time per week were more prevalent among shift workers than among day workers. The highest education level also differed between shift workers and day workers in both sexes. In men, the proportion of participants with more than college level education was higher in day workers, whereas the opposite was observed for women. Shift workers of both sexes were more likely to be unmarried than day workers (P<0.001). Male shift workers did not differ from their day-working counterparts in their income level, whereas female shift workers had significantly different income level compared to their day-working counterparts. Furthermore, the distribution of current smoking, high-risk drinking, and exercise level behaviors did not differ between male day workers and shift workers. However, female shift workers were more likely to be current smokers (P<0.001) and high-risk drinkers (P<0.001) compared to their day working counterparts; however, the exercise habit did not differ significantly between them.
2. Association between Shift Work and Health Behavior
Table 2 shows the association between work type and health behavior in men. There were no statistically significant associations between work type and health behaviors such as smoking, alcohol consumption, and exercise despite adjusting for covariates. Furthermore, an analysis of age-stratified data also did not reveal any significant associations between work type and smoking, alcohol consumption, or exercise habit. However, male shift workers were 1.18 times more likely to have inadequate sleep than male day workers were. A subgroup analysis showed that the 20–39 years old shift workers were 1.39 times (95% confidence interval [CI], 1.06 to 1.81) more likely to have inadequate sleep compared to the day workers.
Table 3 shows the association between work type and health behaviors in women. Compared with the day workers, shift workers had an increased risk of smoking (odds ratio [OR], 1.73; 95% CI, 1.34 to 2.22) and inadequate sleep (OR, 1.24; 95% CI, 1.05 to 1.47), after adjusting for covariates. Subgroup analysis by age showed that the ≥50-years-old shift workers had an increased risk of smoking (OR, 5.55; 95% CI, 3.60 to 8.55), alcohol consumption (OR, 2.22; 95% CI, 1.53 to 3.23), and inadequate sleep (OR, 1.50; 95% CI, 1.10 to 2.05) after adjusting for covariates. There was no statistically significant association between work type and health behavior in the other age groups.
DISCUSSION
In this cross-sectional study of the Korean adult population, we found that shift work was associated with negative health behavior such as smoking, alcohol consumption, and inadequate sleep, although the degree of association differed based on the participants' sex and age.
People may be more prone to smoking during shift work to relieve stress and counter sleepiness and tiredness. Indeed, many previous studies have reported a higher prevalence of smoking among shift workers.891011131724) A study of male blue-collar workers by Knutsson et al.8) revealed that a higher proportion of shift workers were current smokers (shift workers, 54% vs. day workers, 39%). Fujino et al.17) also reported that the Japanese male shift workers had a higher current smoking rate (relative risk ratio [RR], 2.50; 95% CI, 1.39 to 4.51). Consistent with these findings, shift work has also been associated with a higher amount of tobacco consumption in female nurses.10) A study by Trinkoff and Storr13) reported that a night shift of >8 hours was associated with a higher current smoking rate in nurses (OR, 1.62; 95% CI, 1.14 to 2.31). Similarly, another study by Knutsson and Nilsson9) found that shift workers had an increased risk of current smoking (OR 1.3; 95% CI, 1.1 to 1.6). In a follow-up study by van Amelsvoort et al.,12) during the 1-year follow-up period, the proportion of smokers, as well as the number of cigarettes smoked per day by the smokers, increased more for the shift workers compared to the day workers. In another prospective study, van Amelsvoort et al.11) reported that shift workers were more likely to start smoking than their day-working counterparts.
Interestingly, in our study, only the female shift workers were more likely to be current smokers, and the increased risk of smoking was confined to women aged ≥50 years. A possible explanation for this finding could be the difference in smoking prevalence of the studied populations, although we did not test this assumption in our study. The high prevalence (>50% in 2010–2012) of smoking among Korean men suggests that they are more likely to be exposed to smoking.19) Consequently, the common reasons for shift workers to start smoking such as fatigue, or stress, may be less influential in the Korean men compared with other population with lower smoking prevalence. On the other hand, the shift work-related factors may have a greater influence on smoking habit of women than that of men because smoking prevalence is relatively lower among Korean women.19)
Shift workers may have a lower desire to consume alcohol due to lethargy and fatigue, or may be more vulnerable to alcohol consumption due to shift work-related stress. Trinkoff and Storr13) observed that both night shifts with longer working time (>8 hours: OR, 1.40; 95% CI, 1.00 to 1.98) and rotating shifts with longer working time (>8 hours: OR, 1.52; 95% CI, 1.04 to 2.22) were associated with a higher alcohol use in nurses compared to day shifts with shorter working time (≤8 hours). Fujino et al.17) reported an increased risk of habitual drinking (RR, 2.94; 95% CI, 1.62 to 5.32), especially ethanol consumption (≥46 g/d: RR, 6.56; 95% CI, 2.09 to 20.56), in Japanese male shift workers. In our study, however, we observed statistically significant difference in alcohol consumption between day and shift workers only for women aged ≥50 years. Similar to the smoking behavior, the high prevalence of alcohol consumption among the male participants across all age groups (64.8% in 20–39 years, 57.4% in 40–49 years, and 51.4% in ≥50 years) and younger women (34.7% in 20–39 years and 24.4% in 40–49 years vs. 12.1% in ≥50 years) may also be a result of a weaker-than-expected influence of shift work on alcohol consumption.
In a study by Nakamura et al.,18) lack of exercise was reported in a higher proportion of shift workers (69%) compared to day workers (50%), and only approximately 10% of the shift workers exercised at least once a week. Bushnell et al.24) also reported that ‘a lack of exercise’ was associated with rotating shift schedules. Lower prevalence of exercise in shift workers may be due to excessive exertion from work or difficulty in scheduling regular exercise. However, in our study, the exercise prevalence did not differ significantly between the day and shift workers. This lack of significant difference did not change when analysis was repeated after excluding the ‘low-intensity’ exercise subgroup from the ‘exercise group’ (data not shown).
A previous study has reported that morning shift was associated with shorter total sleep time and increased fatigue or the feeling of inadequate rest.14) In another study, shift work was associated with greater difficulty in falling asleep as well as a higher risk of sleepiness at work.15) Pilcher et al.25) reported that the type of shift work and the speed of shift rotation influenced the length of sleep, resulting in both increase and decrease in sleep duration. Other studies have associated shift work with sleep disturbances such as insomnia, or excessive sleepiness.616) Consistent with previous findings, we also observed a higher proportion of inadequate sleep in the shift workers of both sexes. It is plausible that this irregular sleep time may exert undesirable effects on the shift workers' sleep health. Interestingly, we observed that the association between shift work and inadequate sleep was especially evident in 20–39-year-old men and in ≥50-year-old women. However, we could not compare this finding, as other studies have not reported an age-related effect on this association. In addition, we cannot adequately explain this age-specific association in our study.
In this study, the higher prevalence of smoking in shift workers was confined to women. Moreover, the prevalence of smoking, alcohol consumption, and inadequate sleep in the shift workers was also much higher for the female shift workers aged ≥50 years. Several physical and environmental characteristics of women may explain these results. First, women tend to be weaker in terms of basic physical strength than men and may thus feel more fatigue or stress during shift work. Second, women are more vulnerable to hormone imbalances due to the shift work compared to men, and can therefore experience more exhaustion and emotional fluctuations. Third, as is evident from the Korean statistical information, many working women have more domestic duties than men do.26) Taken together, women may have a higher workload that may lead to greater tiredness and exhaustion, as well as emotional stress compared to men. These reasons may explain why the shift work associated unhealthy behaviors are more evident in the women than in the men.
There have been many studies evaluating the relationship between age and shift work. Younger people tend to show better performance compared to older people during extended shift work. Older people are more vulnerable to the changes in circadian rhythm, which results in increased alteration in the quality as well as the quantity of sleep. The older people are more likely to have sleep disorders related to shift work, and may have a decreased ability to recover following shift work compared to younger people.27282930) Despite these findings, to the best of our knowledge, no previous studies have conducted an age-stratified analysis as we report here.
Our study has some limitations. First, our study bears the innate limitations of a cross-sectional study, and we could therefore not confirm the causal effect of shift work on health behavior. Second, we could not include several informative work-related factors such as the type of shift work, labor intensity, type of work, commuting time, and work-related stress, in our analysis due to the lack of data.
In conclusion, this cross-sectional study of a representative sample of Korean adults found that shift work was associated with worse health behavior. Shift work was associated with inadequate sleep in both sexes, and with higher smoking prevalence in women. Age-stratified analysis showed that the association was especially evident in older women. Our findings highlight the importance of implementing active strategies to reduce the negative health behavior in shift workers to prevent/decrease adverse health outcome, and that such strategies should consider the shift workers' demographic characteristics.
Acknowledgments
This research was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT, and future Planning (2014R1A2A2A01002705).
CONFLICT OF INTEREST: No potential conflict of interest relevant to this article was reported.
Table 1 Characteristics of study participants according to the type of work
Values are presented as mean±standard error or %.
*Comparison using a Student t-test for continuous variables and a chi-square test for categorical variables, respectively.
Table 2 Association between shift work and health behaviors in Korean men
OR, odds ratio; CI, confidence interval.
*Adjusted for age, average work hours per week, education level, income level, and marriage status in multiple logistic regression analysis. Age was not adjusted for the age-stratified subgroup analysis. †Assessed by including an interaction term (work type*age group) in the multiple logistic regression analysis. ‡For this analysis, nondrinkers and moderate drinkers were combined into one reference group.
Table 3 Association between shift work and health behaviors in Korean women
OR, odds ratio; CI, confidence interval.
*Adjusted for age, average work hours per week, education level, income level, and marriage status in multiple logistic regression analysis. Age was not adjusted for the age-stratified subgroup analysis. †Assessed by including an interaction term (work type*age group) in the multiple logistic regression analysis. ‡For this analysis, nondrinkers and moderated drinkers were combined into one reference group.
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Korean J Fam MedKorean J Fam MedKJFMKorean Journal of Family Medicine2005-64432092-6715The Korean Academy of Family Medicine 10.4082/kjfm.2017.38.2.93Original ArticleRelationship Between Alcohol Consumption and Prostatic Hyperplasia According to Facial Flushing After Drinking in Korean Men Jang Hak Sun Kim Jong Sung Kim Sung Soo Jung Jin-Gyu Yoon Seok-Joon Yang HyunJu Joung Hyun Chul Department of Family Medicine, Research Institute for Medical Sciences, Chungnam National University School of Medicine, Daejeon, Korea.Corresponding Author: Jong Sung Kim. Tel: +82-42-280-8172, Fax: +82-42-280-7879, jskim@cnuh.co.kr3 2017 22 3 2017 38 2 93 98 19 1 2016 04 4 2016 14 7 2016 Copyright © 2017 The Korean Academy of Family Medicine2017This is an open-access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0/) which permits unrestricted noncommercial use, distribution, and reproduction in any medium, provided the original work is properly cited.Background
The purpose of this study was to examine whether facial flushing after drinking influences the relationship between alcohol consumption and prostatic hyperplasia among Korean men.
Methods
The subjects were 957 Korean men (180 non-drinkers, 389 with drinking-related facial flushing, 388 without facial flushing) in the 40–69 age group, who underwent prostate ultrasound at the health promotion center of Chungnam National University Hospital between 2008 and 2014. Alcohol consumption and alcohol-related facial flushing were assessed through a questionnaire. In terms of the amount consumed, 14 g of alcohol was considered a standard drink. With the non-drinker group as reference, logistic regression was used to analyze the relationship between weekly alcohol intake and prostatic hyperplasia in the flushing and non-flushing groups, with adjustment for confounding factors such as age, body mass index, smoking, and exercise patterns.
Results
Individuals aged 50–59 years who experienced drinking-related facial flushing had a significantly lower risk of prostatic hyperplasia than the non-drinker group, depending on alcohol consumption: ≤4 standard drinks (adjusted odds ratio [OR], 0.38; 95% confidence interval [CI], 0.16 to 0.86); >4 ≤8 standard drinks (OR, 0.35; 95% CI, 0.13 to 0.95); >8 standard drinks (OR, 0.33; 95% CI, 0.13 to 0.84). However, no significant relationship was observed between the number of drinks consumed and the risk of prostate hyperplasia in the non-flushing group.
Conclusion
The risk of prostatic hyperplasia appears to be reduced by alcohol consumption among Korean men aged 50–59 years who exhibit drinking-related facial flushing.
AlcoholsFlushingProstatic HyperplasiaRisk
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INTRODUCTION
Prostatism refers to the enlargement of the prostate, also known as benign prostatic hyperplasia, and is pathologically diagnosed as prostatic stromal cell or epithelial cell proliferation. This condition is closely associated with aging. According to Western studies, 40%–70% of the male population aged ≥60 years are affected.1) In Korea, 22% of men aged ≥50 years have lower urinary tract symptoms related to benign prostatic hyperplasia, which lowers their quality of life.2) Because of the increasing interest in the quality of life among the aging population, benign prostatic hyperplasia has gained importance as a national health issue. Therefore, many studies are under way to investigate the prevalence, cause, and risk factors of benign prostatic hyperplasia in Korea at the community level.
According to a study recently conducted in local communities in Korea, the prevalence of benign prostatic hyperplasia was 36% for men in their 60s, 43% for men in their 70s, and 53% for men in their 80s. The prevalence after adjusting for age was 42%, indicating that the prevalence of benign prostatic hyperplasia had increased compared to that reported in previous studies.3) Some epidemiologic studies have suggested that metabolic syndrome, with clinical features of insulin resistance, lipid metabolism abnormalities, hypertension, and abdominal obesity, appears more frequently in patients with benign prostatic hyperplasia than in unaffected men of the same age group.45) Platz et al.6) reported that the risk of benign prostatic hyperplasia was lower in those who consumed an appropriate amount of alcohol (30.1–50.0 g/d). Similarly, in Korea, Lee et al.7) conducted a study on 514 Korean men and confirmed an inverse relationship between alcohol consumption and benign prostatic hyperplasia.
Although the precise mechanisms underlying this relationship have not yet been elucidated, it is believed that blood estrogen level increases with the quantity of alcohol consumed, while androgen and testosterone levels decrease, ultimately reducing the risk of benign prostatic hyperplasia.89)
Since alcohol metabolism depends on a genetic polymorphism of the aldehyde dehydrogenase 2 (ALDH2) gene, the amount of acetaldehyde produced by the action of ALDH2 is different for each individual, even if the same amount of alcohol is consumed. Most alcohol is broken down through the oxidative pathway where ADH and ALDH2 react. ALDH2 is a protein isoform of aldehyde dehydrogenase, which exists in mitochondria. The ALDH2 polymorphism known as ALDH2*2 is common in Northeast Asians,10) and this ALDH2 polymorphism results in low enzyme activity.
A recent study reported that ALDH2 is related to chronic age-associated diseases such as coronary artery disease and hypertension.11) Seok et al,12) conducted a study on the relationship between missense ALDH2 (SNP: Glu504Lys) and benign prostatic hyperplasia in Koreans.
Facial flushing and various unpleasant physiological responses can occur after alcohol consumption. Alcohol-induced facial flushing occurs because of a lack of the ALDH2 enzyme, which is one of the isoenzymes of ALDH.13) However, no studies have been reported so far on the association between facial flushing and prostatic hyperplasia. Accordingly, this study investigated whether the relationship between the amount of alcohol consumption and prostatic hyperplasia is different for drinkers with and without facial flushing.
METHODS
1. Study Subjects
This study was conducted on men aged between 40 and 70 years who underwent prostate ultrasonography at the health examination center of Chungnam National University Hospital between January 2008 and October 2014. Of 986 patients, 11 who had recently been diagnosed with benign prostatic hyperplasia and prostatitis, eight who were receiving treatment for benign prostatic hyperplasia or hair loss, and 10 who did not answer the survey related to alcohol were excluded. Finally, 957 men participated in this study. The study was approved by the institutional review of board of Chungnam National University Hospital (IRB no.: 2015-09-009).
2. Study Methods
The size of the prostate (in grams) was confirmed through prostate ultrasonography during the health examination. Previous studies used various criteria for the epidemiologic definition of benign prostatic hyperplasia and its size, such as prostatic symptoms, digital rectal examination, the volume on prostate ultrasonography, and uroflowmetry. This study defined prostatic hyperplasia as the presence of a prostate that exceeded 20 g, based on Garraway et al.14)
Alcohol consumption habits, smoking habits, amount of exercise, and presence of facial flushing after consuming alcohol were investigated through self-administered questionnaires, after which primary physicians performed interviews. The study subjects were divided into groups based on their age: those in their 40s, 50s, and 60s. They were also categorized into drinkers and non-drinkers, and the drinkers were sub-categorized into those with and without flushing (flushing and non-flushing group).
Height (m) and weight (kg) were measured with an automatic height–weight measuring device, and height (m) was divided by the square of weight (kg) to calculate the body mass index (BMI). For smoking habits, subjects were divided into those who had never smoked, those who had smoked in the past, and those who were currently smoking. For exercise habits, subjects were classified into four groups depending on whether they performed medium-to-high intensity exercise for longer than 30 minutes: those who did not work out; those who worked out irregularly (once or twice per week); those who worked out regularly (three to five times per week); and those who worked out almost every day.
3. Statistical Analysis
The demographic characteristics of the non-drinkers, flushing, and non-flushing groups were expressed as mean±standard deviation. T-tests were conducted to compare the age, BMI, and prostate size, while the chi-square test was used to compare smoking and amount of exercise, with non-drinkers being the control group.
The flushing and non-flushing groups were divided into three subgroups based on the amount of alcohol consumption per week: ≤4 standard drinks, >4 ≤8 standard drinks, and >8 standard drinks. In order to determine the relationship between the amount of alcohol consumption, flushing status, and prostatic hyperplasia, multivariate logistic regression was used to investigate the relative risk of prostatic hyperplasia in the subgroups in relation to the amount of alcohol consumed, after adjustment for other variables (age, BMI, amount of exercise, smoking habits) based on the non-drinker group. P<0.05 was considered to be statistically significant, and IBM SPSS ver. 21.0 (IBM Corp., Armonk, NY, USA) was used for the statistical analyses.
RESULTS
1. General Characteristics and Alcohol-Related Characteristics of the Study Subjects
Among the 957 subjects, 180 were included in the non-drinker group, 389 in the flushing group, and 388 in the non-flushing group. The age of the subjects was 54.8±7.6 years in the non-drinkers group, 52.0±7.5 years in the flushing group, and 51.1±6.9 years in the non-flushing group, indicating that the age of the drinkers in both the flushing (P<0.001) and non-flushing groups (P<0.001) was significantly lower than that of the non-drinkers.
The proportion of smokers was significantly higher among drinkers, in both the flushing (P<0.01) and the non-flushing group (P<0.01) as compared to non-drinkers: non-drinker group 23.9% (n=43), flushing group 33.7% (n=131), non-flushing group 34.8% (n=135). The prostatic size (gram) measured by ultrasonography was significantly smaller in the drinkers with facial flushing (P<0.01) and without facial flushing (P<0.01) than in the non-drinkers. BMI and exercise habits were not significantly different in the flushing and non-flushing groups compared to the non-drinker group (Table 1).
2. Risk of Prostatic Hyperplasia by Age Group Based on the Amount of Alcohol Consumption in the Flushing Group
Twenty-nine (64.4%) of 45 non-drinkers in their 40s had prostatic hyperplasia. In the flushing group for this same age range, 51 drinkers (64.6%) who had less than four drinks per week, 21 (77.8%) of the drinkers who had four to eight drinks per week, and 25 (65.8%) of the drinkers who had more than eight drinks per week had prostatic hyperplasia. Analysis using the chi-square test for trend in this group (flushing, 40s) showed that the incidence of prostatic hyperplasia had no statistically significant relation with the amount of alcohol consumption (P=0.659).
Among the subjects in their 50s, 72 (87.8%) of 82 non-drinkers had prostatic hyperplasia. In the flushing group of this age, 65 drinkers (70.7%) who had less than four drinks per week, 27 drinkers (71.1%) who had four to eight drinks per week, and 34 drinkers (69.4%) who had more than eight drinks per week had prostatic hyperplasia. Analysis showed that the prevalence of prostatic hyperplasia was significantly lower among this group (flushing, 50s) than in non-drinkers (P=0.019) (Table 2). On multivariate logistic regression, confounding factors such as age, BMI, the amount of exercise, and smoking status were adjusted to calculate the risk of prostatic hyperplasia in drinkers compared to that in non-drinkers. The odds ratio (95% confidence interval [CI]) was 0.38 (0.16–0.86) for drinkers who had less than four drinks per week, 0.35 (0.13–0.95) for drinkers who had four to eight drinks per week, and 0.33 (0.13–0.84) for drinkers who had more than eight drinks per week, indicating that subjects in their 50s with facial flushing after drinking had a lower risk of prostatic hyperplasia compared to non-drinkers (Table 3).
Forty-three (81.1%) of 53 non-drinkers in their 60s had prostatic hyperplasia. Of the drinkers in this age group, 32 (84.2%) who had less than four drinks per week, 14 (93.3%) who had four to eight drinks per week, and 10 (76.9%) who had more than eight drinks per week had prostatic hyperplasia. Analysis of the data using the chi-square test for trend showed no statistical significance (P=0.904) (Table 2).
3. Risk of Prostatic Hyperplasia by Age Group Based on the Amount of Alcohol Consumption in the Non-Flushing Group
The non-flushing group was also analyzed according to the same age groups. The distribution of prostatic hyperplasia according to the weekly alcohol consumption for each age group was compared to that of the non-drinkers, and the difference was not statistically significant (Table 2). Using multivariate logistic regression, with adjustment for confounding factors such as age, BMI, amount of exercise, and smoking status, the risk of prostatic hyperplasia in the non-flushing group compared to the non-drinkers was calculated. The odds ratio (95% CI) for the group in their 40s were 1.37 (0.60–3.14) for drinkers who had less than four drinks per week, 0.42 (0.14–1.22) for drinkers who had four to eight drinks per week, and 0.84 (0.37–1.91) for drinkers who had more than eight drinks per week. The odds ratios for the group in their 50s were 0.59 (0.23–1.52), 0.58 (0.21–1.63), and 0.85 (0.33–2.22), respectively, indicating that the odds ratio decreased with alcohol consumption; however, this was not statistically significant. The odds ratios of the non-flushing group in their 60s were 1.29 (0.36–4.61), 0.24 (0.04–1.69), and 3.07 (0.32–29.12), respectively, again showing no statistically significant difference (Table 3).
DISCUSSION
This study investigated the relationship between prostatic hyperplasia and alcohol consumption, based on the presence or absence of facial flushing after drinking. The current study demonstrated that drinkers in their 50s with facial flushing have a lower risk of developing prostatic hyperplasia than do non-drinkers.
Male hormones need to be supplied consistently in order to develop the prostate and to maintain the function of secretion normally. Men who are castrated before adolescence or who genetically lack androgens experience a rapid cell transformation of the prostatic tissues, which eventually leads to shrinking of the prostate; therefore, they do not develop benign prostatic hyperplasia. In castrated mice, the prostate regrows when male hormones are injected.15161718) Androgens are therefore definitely important in the occurrence of prostatic hyperplasia.
The risk of benign prostatic hyperplasia in terms of alcohol consumption, age, race, BMI, and the extent of exercise has been investigated in previous studies. One of those studies showed that when non-drinkers were compared to drinkers who consumed at least 740 mL (25 oz) of alcohol per month, the risk of benign prostatic hyperplasia decreased to 0.64 (CI, 0.52 to 0.78) for drinkers.19) This inverse relationship between alcohol consumption and benign prostatic hyperplasia showed the same pattern for different types of alcohol, such as wine, beer, and hard liquor.20)
The prostate is highly dependent on male hormones, and many studies have reported that alcohol changes the concentration of blood testosterone, a male hormone. When nine men were asked to consume 1.3 g/kg of alcohol around the same time each day for seven days or the same amount of alcohol all at once within 30 minutes, all of them showed hormonal changes and their testosterone level decreased. 21) In another study, healthy men were asked to consume a set amount of alcohol for four weeks along with balanced meals to examine the effect of alcohol on their testosterone level; the result showed that temporary alcohol consumption and repetitive alcohol consumption lowered the concentration of blood testosterone.22) Moreover, men with alcoholic liver cirrhosis tended to have hypogonadism or become feminized; in such cases, decreased testosterone levels and the resultant increase in estrogen levels lead to a lower risk of benign prostatic hyperplasia, based on autopsy results.2324) However, in other experiments androgens did not play a role as a growth factor of cultured prostate epithelial cells.25)
Compared with various studies of the impact of alcohol consumption on benign prostatic hyperplasia, the current study is unique in that it divided drinkers into those with facial flushing and those without facial flushing. In this study, drinkers in their 50s with facial flushing showed a decrease in the risk of prostatic hyperplasia relative to non-drinkers. Drinkers with facial flushing after alcohol consumption have an excessive amount of acetaldehyde. In such individuals, we expect the higher concentration of aldehyde due to low ALDH2 activity to be related to a lower risk of benign prostatic hyperplasia. However, this finding conflicts with that of a study that reported aldehyde creation to be significantly increased in patients with benign prostatic hyperplasia. 26) More studies are clearly needed, since only in a specific age group, men in their 50s, did we find an inverse relationship between drinking-associated facial flushing and prostatic hyperplasia. Additionally, further research is needed into ALDH2 activity and hormonal conditions that could explain the lower prevalence of prostatic hyperplasia in men who experience facial flushing after drinking.
This study had some limitations. First, it was difficult to find a causal relationship as the study was a cross-sectional study. Second, the sample was taken from one regional hospital in Daejeon; therefore, it is unlikely to represent the entire population of Korean men. Lastly, the study may be biased because only those who are highly interested in their health would have participated in this study.
Despite such limitations, the present study is significant in that it investigated the relationship between alcohol consumption and prostatic hyperplasia based on the presence of facial flushing after alcohol consumption. In addition, our findings suggest that the presence of alcohol-related facial flushing must be considered together with alcohol consumption by the family physician in daily clinical practice.
Conflict of interest: No potential conflict of interest relevant to this article was reported.
Table 1 Characteristics of the subjects
Values are presented as mean±standard deviation or number (%).
*P<0.001, †P<0.01 by the t-test with Bonferroni correlation or chi-square test compared with non-drinkers. ‡Medium-to-high intensity exercise lasting more than 30 minutes: those who did not work out; worked out irregularly (one or two times a week); worked out regularly (three to five times a week); and worked out almost every day. §1 standard drink=14 g of alcohol.
Table 2 Relationship between alcohol consumption and prostatic hyperplasia in the flushing and non-flushing groups
Values are presented as number (%).
*By the chi-square test compared with non-drinkers. †By Fisher's exact test when the model included any cell with n<5.
Table 3 Logistic regression analysis on prostatic hyperplasia risk according to alcohol intake in the flushing and non-flushing groups
*Adjusted for age, body mass index, exercise, and smoking state.
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1 Berry SJ Coffey DS Walsh PC Ewing LL The development of human benign prostatic hyperplasia with age J Urol 1984 132 474 479 6206240
2 Lee E Yoo KY Kim Y Shin Y Lee C Prevalence of lower urinary tract symptoms in Korean men in a community-based study Eur Urol 1998 33 17 21 9471036
3 Lee H Hwa JS Choi BS Choi CW Kim JT Jung SH Correlation between age, prostatic volume and voiding symptoms in randomly selected Korean over age 60 Korean J Urol 1994 35 1208 1213
4 Ozden C Ozdal OL Urgancioglu G Koyuncu H Gokkaya S Memis A The correlation between metabolic syndrome and prostatic growth in patients with benign prostatic hyperplasia Eur Urol 2007 51 199 203 16806666
5 Kim JH Shim BS Hong YS The relating factors of metabolic syndrome to benign prostatic hyperplasia Korean J Urol 2005 46 1046 1050
6 Platz EA Rimm EB Kawachi I Colditz GA Stampfer MJ Willett WC Alcohol consumption, cigarette smoking, and risk of benign prostatic hyperplasia Am J Epidemiol 1999 149 106 115 9921955
7 Lee E Park MS Shin C Lee H Yoo K Kim Y A high-risk group for prostatism: a population-based epidemiological study in Korea Br J Urol 1997 79 736 741 9158512
8 Mendelson JH Mello NK Ellingboe J Effects of acute alcohol intake on pituitary-gonadal hormones in normal human males J Pharmacol Exp Ther 1977 202 676 682 894528
9 Caine M The present role of alpha-adrenergic blockers in the treatment of benign prostatic hypertrophy J Urol 1986 136 1 4 2423716
10 Ohta S Ohsawa I Kamino K Ando F Shimokata H Mitochondrial ALDH2 deficiency as an oxidative stress Ann N Y Acad Sci 2004 1011 36 44 15126281
11 Wang Y Zhang Y Zhang J Tang X Qian Y Gao P Association of a functional single-nucleotide polymorphism in the ALDH2 gene with essential hypertension depends on drinking behavior in a Chinese Han population J Hum Hypertens 2013 27 181 186 22551939
12 Seok H Yoo KH Kim YO Chung JH Association of a missense ALDH2 single nucleotide polymorphism (glu504Lys) with benign prostate hyperplasia in a Korean population Int Neurourol J 2013 17 168 173 24466463
13 Guo R Ren J Alcohol and acetaldehyde in public health: from marvel to menace Int J Environ Res Public Health 2010 7 1285 1301 20617031
14 Garraway WM Collins GN Lee RJ High prevalence of benign prostatic hypertrophy in the community Lancet 1991 338 469 471 1714529
15 Bruchovsky N Lesser B Van Doorn E Craven S Hormonal effects on cell proliferation in rat prostate Vitam Horm 1975 33 61 102 180681
16 Joseph MA Harlow SD Wei JT Sarma AV Dunn RL Taylor JM Risk factors for lower urinary tract symptoms in a population-based sample of African-American men Am J Epidemiol 2003 157 906 914 12746243
17 McConnell JD Roehrborn CG Bautista OM Andriole GL Jr Dixon CM Kusek JW The long-term effect of doxazosin, finasteride, and combination therapy on the clinical progression of benign prostatic hyperplasia N Engl J Med 2003 349 2387 2398 14681504
18 Thompson IM Goodman PJ Tangen CM Lucia MS Miller GJ Ford LG The influence of finasteride on the development of prostate cancer N Engl J Med 2003 349 215 224 12824459
19 Chyou PH Nomura AM Stemmermann GN Hankin JH A prospective study of alcohol, diet, and other lifestyle factors in relation to obstructive uropathy Prostate 1993 22 253 264 7683816
20 Crispo A Talamini R Gallus S Negri E Gallo A Bosetti C Alcohol and the risk of prostate cancer and benign prostatic hyperplasia Urology 2004 64 717 722 15491708
21 Ida Y Tsujimaru S Nakamaura K Shirao I Mukasa H Egami H Effects of acute and repeated alcohol ingestion on hypothalamic-pituitary-gonadal and hypothalamic-pituitary-adrenal functioning in normal males Drug Alcohol Depend 1992 31 57 64 1330472
22 Gordon GG Altman K Southren AL Rubin E Lieber CS Effect of alcohol (ethanol) administration on sex-hormone metabolism in normal men N Engl J Med 1976 295 793 797 958274
23 Green GR Mechanism of hypogonadism in cirrhotic males Gut 1977 18 843 853 590844
24 Frea B Annoscia S Stanta G Lozzi C Carmignani G Correlation between liver cirrhosis and benign prostatic hyperplasia: a morphological study Urol Res 1987 15 311 314 2446412
25 McKeehan WL Adams PS Rosser MP Direct mitogenic effects of insulin, epidermal growth factor, glucocorticoid, cholera toxin, unknown pituitary factors and possibly prolactin, but not androgen, on normal rat prostate epithelial cells in serum-free, primary cell culture Cancer Res 1984 44 1998 2010 6370422
26 Merendino RA Salvo F Saija A Di Pasquale G Tomaino A Minciullo PL Malondialdehyde in benign prostate hypertrophy: a useful marker? Mediators Inflamm 2003 12 127 128 12775364
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Korean J Fam MedKorean J Fam MedKJFMKorean Journal of Family Medicine2005-64432092-6715The Korean Academy of Family Medicine 10.4082/kjfm.2017.38.2.99Case ReportConfusion, Faciobrachial Dystonic Seizures, and Critical Hyponatremia in a Patient with Voltage-Gated Potassium Channel Encephalitis Yaxley Julian Department of Internal Medicine, Redcliffe Hospital, Redcliffe, Queensland, Australia.Corresponding Author: Julian Yaxley. Tel: +61-420808049, Fax: +61-1300364952, julianyaxley@yahoo.com.au3 2017 22 3 2017 38 2 99 101 10 5 2016 07 6 2016 10 6 2016 Copyright © 2017 The Korean Academy of Family Medicine2017This is an open-access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0/) which permits unrestricted noncommercial use, distribution, and reproduction in any medium, provided the original work is properly cited.Autoimmune limbic encephalitis is a rare cause of encephalitic disease. It is associated with various target antigens and is difficult to diagnose, and experience with its treatment is limited. This case report describes a 69-year-old man, who presented with life-threatening hyponatremia and confusion, following several months of gradually worsening faciobrachial dystonic seizures. Faciobrachial dystonic seizures are a well-described feature classically observed in voltage-gated potassium channel autoimmune encephalitis. The presence of chronic hyponatremia without cognitive dysfunction, eventually culminating in an acute episode of encephalopathy and severe hyponatremia, is a pattern of natural history not previously documented in this condition.
SeizureDystoniaEncephalitisHyponatremia
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INTRODUCTION
Autoimmune encephalitis is a rare disease which is only recently described. Its natural history is not fully understood although various responsible antigens have been identified. This case report describes a pathognomonic clinical sign which ultimately secured a diagnosis of VGKC limbic encephalitis and expedited appropriate treatment.
CASE REPORT
A 69-year-old man presented to his primary care physician with a recent onset of intermittent painful spasms of his right arm and face. Routine electrolytes were measured and were notable only for a serum sodium level of 130 mmol/L (reference range, 135 to 145 mmol/L). The patient was diagnosed with cramps and advised to increase dietary salt intake. His spasms increased in frequency over the following months, but the patient did not seek further medical attention. Two months after his initial consultation with the general practitioner, the patient was transported to the emergency department by an ambulance with acute confusion and imbalance. This was accompanied by a near-constant, right-sided, spasmodic jerking. The patient's wife reported that until the day of presentation to the emergency department, his cognition and gait had been completely normal. During the twitching episodes, his level of consciousness had never been impaired.
The patient's past medical history was notable for an ischemic stroke 8 years earlier, with mild residual weakness of the upper left limb, hypertension, and post-traumatic stress disorder. His medications included aspirin, atorvastatin, irbesartan, and venlafaxine. The patient was a retired soldier and a non-smoker, who consumed alcohol only socially.
On examination in the emergency department, the patient was confused and agitated. He reacted to voice by opening his eyes, but he could only manage unintelligible speech. He was uncooperative and detailed neurological examination was difficult. All limbs appeared to move equally, and pupils were isocoric and sluggishly reactive to light. Brief stereotyped involuntary contractions of the right side of the face and upper limb were noted every 2–3 minutes. These were characterized by facial contortion, and right elbow and wrist flexion, and finger extension. There were no features of infection or trauma.
The results of serum biochemistry on arrival were notable for an abnormal sodium concentration of 113 mmol/L and serum osmolality of 241 mmol/L (range, 275 to 295 mmol/L). A baseline serum sodium obtained by the family physician 12 months earlier was within the normal range at 136 mmol/L. Urine sodium concentration was 122 mmol/L with osmolality of 541 mmol/L. A full blood count and tests for inflammatory markers returned results within the normal ranges. Emergency brain computed tomography did not reveal any notable changes.
The patient's mental status improved rapidly, following urgent treatment with 3% hypertonic saline and, subsequently, fluid restriction. Electroencephalogram (EEG) showed frontotemporal slowing with no epileptiform activity. Magnetic resonance imaging (MRI) of the brain demonstrated only deep white matter hyperintensities, consistent with chronic small vessel ischemia. Analysis of cerebrospinal fluid (CSF), obtained by lumbar puncture, did not detect abnormalities in protein or glucose levels, microscopic examination, or bacterial culture results.
Twitches remained obvious and frequent over the following week. These were thought to be consistent with faciobrachial dystonic seizures (FDSs), typical of one variant of autoimmune limbic encephalitis related to voltage-gated potassium channel antibodies (VGKC antibodies). Empiric treatment with intravenous methylprednisolone and immunoglobulin was commenced. A full resolution of the patient's abnormal movements was observed within several days.
Serum paraneoplastic antibodies were negative. Reanalysis of the CSF identified elevated VGKC antibodies (589 pM, normal range <85 pM), leading to a final diagnosis of voltage-gated potassium channel encephalitis. This was thought to have caused the syndrome of inappropriate secretion of anti-diuretic hormone (SIADH), which induced critical hypoosmolar hyponatremia, with confusion and ataxia.
Following hospitalization, the patient remained stable in the community on a regimen of daily oral prednisone and monthly intravenous immunoglobulin (IVIG).
DISCUSSION
Patients with encephalitic syndromes present a diagnostic challenge. Autoimmune limbic encephalitis is a recently described entity, whose pathogenesis remains poorly understood. The inflammatory process is confined largely to structures of the limbic system and several antigenic targets have been implicated including VGKCs, the glutamate NMDA (N-methyl-D-aspartate) and AMPA (α-amino-3-hydroxy-5-methylisoxazole-4-propionic acid) receptors, and GABA (gamma-aminobutyric acid) receptors.
VGKC encephalitis is a rare disease and an uncommon variety of limbic encephalitis. The true incidence of VGKC encephalitis is unknown, although it is increasingly recognized. While this condition is conventionally attributed to an autoimmune reaction against the VGKC, it is now known that antibodies used in laboratories to test for VGKC in fact act on leucine-rich glioma-inactivated protein 1 (LGI1), a neuronal secreted protein, which is a structural component of the VGKC complex.12) Some authors, therefore, refer to anti-LGI1 antibody or anti-VGKC-complex antibodies instead of anti-VGKC antibody, and may replace the term ‘VGKC encephalitis’ with ‘LGI1 encephalitis’.3)
Many cases of autoimmune limbic encephalitis are paraneoplastic. In the VGKC subtype the incidence of cancer is relatively lower at 11%.3) Features of VGKC encephalitis typically precede detection of malignancy.3) The tumors most commonly associated with VGKC encephalitis are small cell lung cancer and thymoma.
Reported clinical manifestations of VGKC encephalitis include altered memory and behavior, confusion, drowsiness, and psychosis. The acute delirium observed in our case, with previously normal mental function, is an unusual presentation of the disease. Typically, almost all patients demonstrate subtle cognitive dysfunction for at least 1 week prior to the development of a clinically obvious syndrome.4) Dystonia and chorea are frequently seen, and are often the first sign of VGKC encephalitis, predating other symptoms by weeks, as was demonstrated in our case. FDSs are a pathognomonic feature of VGKC encephalitis. 56) These are not true seizures, but rather dystonic reactions that are not observed in other forms of autoimmune limbic encephalitis. FDSs usually evolve over weeks or months, but fulminant presentations do occur.
Establishing the diagnosis of VGKC encephalitis can be difficult. There is no single diagnostic test, although lumbar puncture and CSF analysis are central. Most patients have raised CSF protein and many have a lymphocytic pleocytosis.3) VGKC antibodies are detected in the CSF in the great majority of patients.37) The VGKC antibodies may also be identified in the serum, although false positives are more frequent. The EEG is usually non-specific, with frontotemporal or bitemporal generalized slowing. Some patients have epileptiform activity. Neuroimaging can support the diagnosis, but findings are not conclusive. Brain MRI results usually find high-signal changes in medial temporal lobes, which are enhanced on T2-weighted scans.3) Fludeoxyglucose positron emission tomography (FDG-PET) results often reveal hypermetabolism in the basal ganglia and the temporal lobes, and, at the later stages, the disease may demonstrate hypometabolism in the frontotemporal cortex.89) Clinicians should be aware that, because VGKC encephalitis sometimes represents a paraneoplastic syndrome, evaluation for occult malignancy should be considered for every patient.
Approximately 80% of cases of VGKC encephalitis develop hyponatremia at some time during the illness, generally as a result of SIADH.10) The pattern of hyponatremia observed in our case is unique. Previously, low serum sodium has only been reported in patients with prior evidence of encephalopathy, such as subacute memory impairment or worsening irritability.10) Asymptomatic, mild hyponatremia was apparent in our patient 2 months prior to the sudden onset of confusion, and, by the time of presentation, had progressed to critically low serum sodium concentration. Given the prompt improvement in his mental state, upon reversal of hyponatremia, it is hypothesized that this patient's encephalopathy was a consequence of critical hyponatremia, rather than cognitive deficits from encephalitis per se.
Most patients experience full recovery with immunomodulatory therapy, and relapse is uncommon. Some exhibit subtle residual neurological deficits. Earlier detection is presumed to lead to better neurologic outcomes.310) There is very little scientific evidence to direct treatment for autoimmune encephalitis; with empirical experience, corticosteroids and IVIG have become the most commonly used agents.10) Other immunosuppressive treatments that have been trialed successfully, include plasma exchange, rituximab, and mycophenolate. Anticonvulsants have little impact on faciobrachial dystonic seizures, but are indicated in true seizures.5)
In summary, VGKC encephalitis is a rare disease, which, if detected, is amenable to treatment. The pattern of presentation in our case has not been previously reported in medical literature. While hyponatremia is a common finding in VGKC encephalitis, asymptomatic, chronically low serum sodium preceding an acute delirium is unusual. The combination of FDSs and mild hyponatremia thereby provided an early opportunity for diagnosis, which was missed and ultimately led to an acute life-threatening process. The fact that this patient presented initially to primary care highlights the importance of the understanding of VGKC encephalitis by general practitioners.
CONFLICT OF INTEREST: No potential conflict of interest relevant to this article was reported.
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1 Lai M Huijbers MG Lancaster E Graus F Bataller L Balice-Gordon R Investigation of LGI1 as the antigen in limbic encephalitis previously attributed to potassium channels: a case series Lancet Neurol 2010 9 776 785 20580615
2 Tofaris GK Irani SR Cheeran BJ Baker IW Cader ZM Vincent A Immunotherapy-responsive chorea as the presenting feature of LGI1-antibody encephalitis Neurology 2012 79 195 196 22744657
3 Wingfield T McHugh C Vas A Richardson A Wilkins E Bonington A Autoimmune encephalitis: a case series and comprehensive review of the literature QJM 2011 104 921 931 21784780
4 Vincent A Buckley C Schott JM Baker I Dewar BK Detert N Potassium channel antibody-associated encephalopathy: a potentially immunotherapy-responsive form of limbic encephalitis Brain 2004 127 Pt 3 701 712 14960497
5 Sen A Wang J Laue-Gizzi H Lee T Ghougassian D Somerville ER Pathognomonic seizures in limbic encephalitis associated with anti-LGI1 antibodies Lancet 2014 383 2018 24910233
6 Chang BS The face (and arm) of treatment for seizures in VGKC/LGI1 antibody-associated limbic encephalitis Epilepsy Curr 2014 14 180 182 25170310
7 Lawn ND Westmoreland BF Kiely MJ Lennon VA Vernino S Clinical, magnetic resonance imaging, and electroencephalographic findings in paraneoplastic limbic encephalitis Mayo Clin Proc 2003 78 1363 1368 14601695
8 Navarro V Kas A Apartis E Chami L Rogemond V Levy P Motor cortex and hippocampus are the two main cortical targets in LGI1-antibody encephalitis Brain 2016 139 Pt 4 1079 1093 26945884
9 Basu S Alavi A Role of FDG-PET in the clinical management of paraneoplastic neurological syndrome: detection of the underlying malignancy and the brain PET-MRI correlates Mol Imaging Biol 2008 10 131 137 18297363
10 Irani SR Michell AW Lang B Pettingill P Waters P Johnson MR Faciobrachial dystonic seizures precede Lgi1 antibody limbic encephalitis Ann Neurol 2011 69 892 900 21416487
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Contemp Oncol (Pozn)Contemp Oncol (Pozn)WOContemporary Oncology1428-25261897-4309Termedia Publishing House 2518110.5114/wo.2015.51823Case ReportAxitinib in sequential therapy in metastatic renal cell carcinoma Kuchar Agata 1Hryciuk Beata 1Stec Rafał 1Mączewski Michał 2Szczylik Cezary 11 Military Institute of Medicine, Warsaw, Poland2 Centre of Postgraduate Medical Education, Warsaw, PolandAddress for correspondence: Agata Kuchar MD, Military Institute of Medicine, Szaserów 128, 04-141 Warsaw, Poland. e-mail: a_kuchar@wp.pl20 12 2016 2016 20 5 418 420 21 9 2014 23 1 2015 Copyright: © 2016 Termedia Sp. z o. o.2016This is an Open Access article distributed under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International (CC BY-NC-SA 4.0) License, allowing third parties to copy and redistribute the material in any medium or format and to remix, transform, and build upon the material, provided the original work is properly cited and states its license.Efficacy of new molecularly targeted drugs in the treatment of renal cell carcinoma (RCC), confirmed in clinical studies in relation to survival and prolongation of time to progression, has became a big chance for patients with metastatic renal cell cancer. Axitinib is a potent and selective receptor tyrosine kinase for vascular endothelial growth factor (VEGFR-1, -2, -3), platelet-derived growth factor β (PDGRF-β) and c-KIT.
This is a case report of a 57-year old female patient with a history of left nephrectomy due to clear cell renal cell carcinoma. The patient had received three prior systemic treatments (interferon – sorafenib – everolimus). After consecutive progression the patient was qualified to 4th line therapy – axitinib at a dose of 5 mg twice daily. Partial response to treatment was achieved. After 6 months therapy was stopped due to the disease progression. The total time to progression was 37.5 months. The total survival time from the disease diagnosis was 45 months.
Based on literature date and own experience we showed that sequential treatment RCC is associated with improved survival. In summary, axitinib may be an effective drug after failure of tyrosine-kinase inhibitor (TKI) therapy in previous lines of therapy.
renal cell carcinomasequential therapyaxitinibtargeted therapies
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Introduction
Renal cell carcinoma (RCC) accounts for approximately 3% of all malignancies. Males predominate among patients (1.5 : 1) and peak incidence is between 60 and 70 years of age [1]. At the time of diagnosis disseminated disease is found in 30% of patients. Lungs, bones, liver and brain are the most common locations of distant metastases of RCC. Disseminated renal cell cancer is considered as incurable disease; average patient survival in the era of targeted therapy is approximately 7.8–43.2 months (depending on the Database Consortium Model risk group) and 5-year survival rate is 0–13% [2, 3].
Recent studies demonstrated that metabolic pathways associated with membrane receptors for growth factors play an important role in RCC etiology and proteins of tyrosine and serine-threonine kinase activity have become a new therapeutic target as well as monoclonal antibodies. Efficacy of new molecularly targeted drugs (sorafenib 2005, sunitinib 2006, temsirolimus 2007, bevacizumab 2009, everolimus 2009, pazopanib 2009, axitinib 2012) in the treatment of RCC, confirmed in clinical studies in relation to survival and prolongation of time to progression, has became a big chance for patients with metastatic renal cell cancer [4–8].
Case report
This is a case report of a 57-year old female patient with a history of left nephrectomy due to clear cell RCC in December 2008. The patient was in favorable prognostic categories according to Motzer et al. The patient had no family history of malignant neoplasm and no history of chronic diseases. Due to metastatic disease (metastases in lungs), interferon immunotherapy was used as a first line therapy. The best response to treatment was partial regression according to RECIST criteria (version 1.0). After 11 months immunotherapy was stopped due to the disease progression – enlargement of existing lesions. In April 2010 the patient was qualified to 2nd line therapy with a tyrosine kinase inhibitor (sorafenib). The patient received a total of 8 chemotherapy courses. The response to treatment was stable disease according to RECIST criteria. In December 2010, due to the disease progression – appearance of new focal lesions in the liver, the patient was qualified to 3rd line therapy using a selective mTOR inhibitor (everolimus). Marked toxicity was observed during the therapy – anemia grade 3 according to CTC AE that required transfusion of packed red blood cells. The treatment was stopped after 13 courses in January 2012 due to the disease progression – appearance of new lesions in lungs, left adrenal gland and the skeletal system. The patient underwent palliative radiotherapy on the tumor site, 11th rib in January 2012, and then in June 2012 on central nervous system (CNS) area due to focal lesions located in the right parietal and temporal lobes and in the right cerebellar hemisphere. In May 2012 the patient started a 4th line therapy, axitinib at a dose of 5 mg twice daily. Partial response to treatment was achieved. The treatment was stopped in November 2012 due to the disease progression. The total time to progression was 37.5 months (Fig. 1). The patient died in December 2012. The total survival time from the disease diagnosis was 45 months.
Fig. 1 Progression-free survival (PES)
The treatment was carried out in accordance with NCCN (National Comprehensive Cancer Network) recommendations and with polish National Health Service.
Discussion
In January 2012, basing on AXIS study, another drug was approved in the USA for the treatment of an advanced RCC after failure of one line of therapy – axitinib. Axitinib is a potent [50–450-fold more potent that previously used vascular endothelial growth factor receptor (VEGFR) inhibitors] and selective receptor tyrosine kinase for VEGFR-1, -2, -3, platelet-derived growth factor β (PDGRF-β) and c-KIT [9–11]. Axitinib was shown to potently inhibit VEGFR-dependent proliferation and survival of endothelial cells. In blood vessel of a tumor xenograft, axitinib inhibits phosporylation of VEGFR-2 that is expressed at the target site in vivo and retards tumor growth, results in regression and inhibition of metastases in multiple experimental models of tumors [12]. Table 1 shows summary of clinical trials of axitinib in metastatic renal cell carcinoma.
Table 1 Summary of clinical trials of axitinib in metastatic renal cell carcinoma
Authors Phase Number of patients Prior therapy Median PFS (months) Median OS (months)
Rixe et al. (2007) II 52 cytokines 15.7 (95% CI: 8.4–23.4) 29.9 (20.3 – NR)
Rini et al. (2009) II 62 sorafenib ± other 7.4 (95% CI: 6.7–11.0) 13.6 (95% CI: 8.4–18.8)
Rini et al. (2011) III 723 sunitinib other cytokines ± bevacizumab other temsirolimus 6.7 (95% CI: 6.3–8.6) NR
CI – confidence interval; NR – not reached; PFS – progression-free survival; OS – overall survival
AXIS was the first phase 3 study of axitinib in the renal cell cancer. This study enrolled 723 patients with an advanced renal cell cancer who progressed during or after a first line therapy. Three hundred and eighty-nine (53.8%) of these patients previously received sunitinib based therapy, 251 (34.7%) a cytokine based therapy (interleukin-2 or interferon α), 59 (8.2%) bevacizumab based therapy, 24 (3.3%) temsirolimus based therapy. The patients were randomized in 1 : 1 ratio to groups receiving axitinib (n = 361) or sorafenib (n = 362). The primary end point of this study was progression free survival (PFS), while overall survival (OS) was secondary end point. In the whole study population, a statistically significant benefit was found for axitinib versus sorafenib with regard to the primary end point (6.7 vs. 4.7 months, HR = 0.66; p < 0.0001). In the subgroup analysis axitinib was more effective than sorafenib in patients receiving cytokines (12.1 vs. 6.5 months; HR = 0.46; p < 0.0001) and sunitinib (4.8 vs. 3.4 months; HR = 0.71; p = 0.01) as the first line therapy. No statistically significant differences with regard to PFS between the study groups were found for patients previously treated with bevacizumab or temsirolimus. No statistically significant differences with regard to the secondary end point (OS) were found between the study arms both in the whole population as well as in the subgroups defined by previous therapy. Rate of grade > 3 toxicity according to CTCAE was similar in both groups. Hand foot syndrome was more common in patients treated with sorafenib (16% vs. 5%), while diarrhea (11% vs. 7%) and hypertension (16% vs. 11%) were more common in patients treated with axitinib. The treatment was stopped due to toxicity in 4% of patients receiving axitinib and in 8% of patients receiving sorafenib.
A phase 2 study that assessed efficacy and safety of axitinib in 52 patients was published in 2007 [13]. The drug was administered as the 2nd line therapy in patients with advanced renal cell cancer who stopped treatment with interferon α, interleukin-2 or both these drugs due to the disease progression or unacceptable toxicity. Twenty-two patients belonged to the group with favorable prognosis, while 30 to intermediate one. Median time to progression was 15.7 months, and median overall survival time was 29.9 months. Two complete responses to treatment were observed and 21 partial responses, accounting for overall objective response rate of 44.2% (95% CI: 30.5–58.7). An average duration of response was 23 months. Despite the fact that 28 patients experienced grade 3 or 4 toxicity, they were managed and controlled through modifications of the drug dose and supportive therapy.
Another phase 2 study conducted in 2009 proved effectiveness of axitinib therapy in patients with an advanced renal cell cancer with a history of sorafenib therapy [14]. The study enrolled 62 patients. For 29% of patients it as a 3rd or higher line of therapy with antiangiogenic drugs, while all patients previously received sorafenib therapy. Partial response to treatment was observed in 14 (23%) patients, while stable disease in 11 (18%) patients. An average time to progression was 7.4 months, while an average overall survival time was 13.6 months.
The treatment toxicities were, as in the previous study, controlled and managed through modifications of the drug dose and supportive therapy.
Results of previously conducted studies indicate that sequential use of tyrosine kinase inhibitors (TKI) does not induce cross resistance. On the other hand, it may even overcome resistance to a previously used TKI. Tolerance and toxicity of sequentially used drugs is similar to that encountered for each drug used alone. Furthermore, basing on growing number of retrospective analyses, each line of therapy was shown to have additive effect on PFS and prolong overall PFS [15–26]. Sequential use of the following regimen: TKI – m-TOR inhibitors – TKI could be a good choice in the treatment of mRCC but larger and appropriate studies are require to provide evidence for standard sequencing treatment [25–28].
In summary, axitinib may be an effective drug after failure of TKI therapy failure in previous lines of therapy, which is supported by this case report and retrospective analyses. This hypothesis requires confirmation in prospective, randomized clinical trials.
The authors declare no conflict of interest.
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Contemp Oncol (Pozn)Contemp Oncol (Pozn)WOContemporary Oncology1428-25261897-4309Termedia Publishing House 2518310.5114/wo.2015.51825Review PaperMethods and results of locoregional treatment of brain metastases in patients with non-small cell lung cancer Patla Anna 1Walasek Tomasz 1Jakubowicz Jerzy 2Blecharz Paweł 3Mituś Jerzy Władysław 4Mucha-Małecka Anna 2Reinfuss Marian 11 Department of Radiotherapy, Maria Sklodowska-Curie Memorial Cancer Centre and Institute of Oncology, Krakow Branch, Poland2 Department of Oncology, Maria Sklodowska-Curie Memorial Cancer Centre and Institute of Oncology, Krakow Branch, Poland3 Department of Gynaecological Oncology, Maria Sklodowska-Curie Memorial Cancer Centre and Institute of Oncology, Krakow Branch, Poland4 Department of Surgical Oncology, Maria Sklodowska-Curie Memorial Cancer Centre and Institute of Oncology, Krakow Branch, PolandAddress for correspondence: Anna Patla, Radiotherapy Department, Centre of Oncology – Maria Skłodowska-Curie Memorial Institute, Cracow Branch, Garncarska 11, 31-115 Kraków. tel. +48 12 422 99 00 ext. 207. e-mail: apatla@wp.pl20 12 2016 2016 20 5 358 364 18 3 2014 01 7 2014 Copyright: © 2016 Termedia Sp. z o. o.2016This is an Open Access article distributed under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International (CC BY-NC-SA 4.0) License, allowing third parties to copy and redistribute the material in any medium or format and to remix, transform, and build upon the material, provided the original work is properly cited and states its license.This article presents methods and results of surgery and radiotherapy of brain metastases from non-small cell lung cancer (BMF-NSCLC). Patients with single BMF-NSCLC, with Karnofsky score ≥ 70 and controlled extracranial disease are the best candidates for surgery. Stereotactic radiosurgery (SRS) is recommended in patients with 1–3 BMF-NSCLC below 3–3.5 cm, with minor neurological symptoms, located in parts of the brain not accessible to surgery, with controlled extracranial disease. Whole brain radiotherapy (WBRT) following SRS reduces the risk of local relapse; in selected patients median survival reaches more than 10 months. Whole brain radiotherapy alone is a treatment in patients with multiple metastases, poor performance status, uncontrolled extracranial disease, disqualified from surgery or SRS with median survival 3 to 6 months. There is no doubt that there are patients with BMF-NSCLC who should receive only the best supportive care. There is a debate in the literature on how to select these patients.
non-small cell lung cancerbrain metastasesradiation therapy
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Introduction
Lung cancer is the most common cause of brain metastases (40–50%), and comes before breast cancer (15–25%) and melanoma (5–15%) in this respect [1–6]. In patients with non-small cell lung cancer (NSCLC), accounting for 80–85% of all lung cancers, the risk of development of brain metastases (BMF-NSCLC) throughout the course of the disease is 30–50%; brain metastases are found in 7–10% of patients with NSCLC at diagnosis [7–18]. The risk of BMF-NSCLC development is significantly higher in patients with advanced NSCLC (stage III and IV) and in patients with adenocarcinoma and large-cell carcinoma, as compared to squamous-cell carcinoma histology [12–14, 19, 20]. Hsiao et al., in an analysis of 482 patients with stage IIIb–IV NSCLC, found that the risk of brain metastasis was statistically significantly higher in women, patients aged less than 60 years and in patients with adenocarcinoma histology [7].
In over 50% of patients BMF-NSCLC occur synchronously, and in 45–50% of patients multiple focal lesions are found; 5–15% patients are asymptomatic and brain metastases are found in them on imaging studies [10, 12, 14].
Occurrence of BMF-NSCLC is associated with a very poor prognosis: median survival of untreated patients is about 1 month [1, 6, 8, 10, 11, 15, 17, 18, 21, 22] and of those receiving palliative corticosteroid treatment slightly over 2 months [17, 18]. Palliative whole brain radiotherapy (WBRT) prolongs median survival to 3–6 months [8, 10, 17]. For many years, these extremely poor treatment results caused exclusion of patients with BMF-NSCLC from any controlled clinical studies that investigated e.g. systemic treatment. However, in recent years a positive change has been observed [15, 22]. In patients qualified for definitive surgery or stereotactic radiosurgery (SRS), with or without WBRT, median survival reaches even more than 10 months; however, this is true only for selected patients: with good performance status, complete or very good extracranial disease control and 1–3 BMF-NSCLC [8, 15, 18, 23–27].
The following methods are used in the treatment of BMF-NSCLC: surgery, SRS, WBRT, systemic treatments (chemotherapy, immunotherapy) and various combinations of these methods [1, 2, 4–6, 8, 9, 11, 12, 17–19, 26, 28–35]. In general, local (surgery, SRS) [1, 4, 6, 8, 17, 18, 28–30, 35] or regional (WBRT) [1, 4, 19, 28–30, 33–35] treatment is preferred, including combination of surgery and radiotherapy. There is a growing importance of systemic treatment, in particular of immunotherapy [1, 2, 4, 11, 12, 30–32].
Surgery
Three controlled clinical studies have compared the efficacy of surgery combined with WBRT to that of WBRT alone, in patients with single brain metastasis, mainly from NSCLC [36–38]. The results of these studies are presented in Table 1.
Table 1 Results of controlled clinical studies comparing the efficacy of surgery combined with WBRT to that of WBRT alone
Authors, publication year, reference no. % of patients with extracranial disease control Method of treatment of brain metastases Number of patients treated Median survival p
log-rank test
Patchell et al., 1990 [36] 62.5 WBRT
surgery + WBRT 23
25 15 weeks
40 weeks < 0.01
Vecht et al., 1993 [37] 68.3 WBRT
surgery + WBRT 31
32 3 months
15 months 0.04
Mintz et al., 1996 [38] 21.4 WBRT
surgery + WBRT 43
41 6.3 months
5.6 months NS
NS – non-significant
In the study of Patchell et al., median survival was 15 weeks in patients treated with radiotherapy alone and 40 weeks in the group of patients treated with surgery; time to relapse or progression of brain lesions was 21 weeks and 59 weeks, respectively [36]; both differences were highly statistically significant. The study by Vecht et al. has confirmed the statistically significant positive effect of surgery on patients’ survival, expressed as prolongation of median survival by 12 months [37].
In a study by Mintz et al., no improvement of survival of patients treated with surgery and WBRT was found, as compared to patients treated with WBRT alone. It should be stressed however that in this study, extracranial disease control was achieved in only 21% of patients, whereas in the previous two studies this control was found in over 60% of patients. Additionally, patients analysed by Patchell et al. had a MRI scan before surgery, whereas it was not done in any patient from the group studied by Mintz, which puts into question unifocality of brain lesions in the latter group [36, 38].
Qualification of patients for surgical treatment of BMF-NSCLC is based on assessment of three basic factors: patient’s performance status, level of extracranial disease control and brain lesion status [4, 6, 30]. Patients with single BMF-NSCLC, with Karnofsky score (KPS) of 70 or more and controlled extracranial disease are the best candidates for surgery [4, 29]. According to Mamelak et al., combination of surgery and WBRT in this group of patients allows 5-year survival to be achieved in 10–20% of patients [4].
It is however unquestionable that the level of extracranial disease control has a significant impact on the patient’s future and on the decision whether to perform surgical treatment of BMF-NSCLC [23]. Analysis of the study of Mintz et al. clearly shows that the majority of deaths resulted from locoregional NSCLC progression or from distant extracranial metastasis and not from the presence of BMF-NSCLC themselves [38]. In general, BMF-NSCLC surgery is not recommended for patients with life expectancy not exceeding 3 months [4, 6].
In some patients surgical treatment may be justified irrespective of the level of extracranial disease control; the following patients are included:
patients with large (> 3 cm) tumours, causing significant neurological deficit and/or high intracranial hypertension (mass effect),
patients with tumours located in the posterior cranial fossa, with a risk of secondary hydrocephalus or brainstem compression,
patients with haemorrhagic, necrotic or cystic tumours, with a surrounding oedema zone.
Nowadays, presence of more than one BMF-NSCLC is not a contraindication for surgical treatment of brain metastases; even if resection of all BMF-NSCLC is impossible, removal of one or more metastases that are particularly burdensome to the patient may be justified [6, 39–41]. Surgery may also be indicated in case of uncertain nature of brain lesions or if there is a need to determine biological features of BMF-NSCLC that may affect selection of e.g. targeted therapy [4, 6, 29].
Appropriate qualification of patients for surgical treatment of BMF-NSCLC ensures good tolerance and lack of complications. Improvement of local efficacy of BMF-NSCLC surgery may be expected along with progress of surgical technique, including in particular en bloc resections and resections with clear microscopic margins [29, 42, 43].
Radiotherapy
Stereotactic radiosurgery
Stereotactic radiosurgery may be performed with three types of radiation: high energy photons obtained from linear accelerators, gamma rays from a cobalt unit (gamma-knife) and relatively rarely, due to limited availability, with a proton beam from a cyclotron. According to protocol RTOG 90-05, the maximum tolerated single dose of radiation for a tumour of a diameter of 31–40 mm is 15 Gy, of 21–30 mm – 18 Gy and below 20 mm – 24 Gy [30, 35, 44]. Slightly lower doses are suggested for BMF-NSCLC located in or near the brain stem, optic nerves and optic chiasm [4].
Stereotactic radiosurgery is used as:
the only treatment method for selected patients with BMF-NSCLC,
the primary treatment method, followed by WBRT,
a method of local dose escalation (boost) after WBRT,
a method of treatment of BMF-NSCLC relapses, after both WBRT and SRS (re-SRS).
The best candidates for SRS treatment are patients:
with single (1–3) BMF-NSCLC, of a diameter not exceeding 3–3.5 cm,
with BMF-NSCLC located in all brain regions including those not accessible to surgery,
with no or only minor neurological symptoms,
with controlled extracranial disease [4, 30, 35].
Stereotactic radiosurgery efficacy in the treatment of BMF-NSCLC has been confirmed unequivocally in numerous retrospective and prospective studies [4, 8, 17, 18, 28, 30, 35, 44–59]. A response to SRS (decreased size of the metastasis or its growth inhibition) is found in 80–93% of patients, 1-year local control in 61–86% of patients; median survival ranges from 7 to 14 months [4, 8, 18, 35, 49, 50]. Acute toxicity develops in 5–18% of patients undergoing SRS, and includes headache, nausea, exacerbation of existing neurological symptoms, epilepsy; a late complication may be radiation-induced brain necrosis that is found in 2–6% of patients, with a clear association with SRS dose and with the size of the target volume [4, 35, 44].
In 2004, Hu et al. reported that in a group of patients with stage I NSCLC according to the AJCC, patients with single BMF-NSCLC had similar survival as patients with disease of the same stage without BMF-NSCLC, provided that an aggressive treatment (chemo-radiotherapy) of chest lesion and surgery or SRS of the brain metastasis were performed [56]. In 2008, Flannery et al. analysed a group of patients treated with curative intent for NSCLC, with a single synchronous BMF-NSCLC treated with SRS; median survival of patients was 18 months, and 5-year overall survival was 21% [57]. In 2010, Mariya et al. described a group of 84 patients treated initially with SRS; in 44 (52.4%) patients 1 metastasis was found, in 27 (32.1%) – 2, in 8 (9.5%) – 3, and in 5 (6.0%) more than 4 BMF-NSCLC. One- and 5-year overall survival was 38% and 11%, respectively, and median survival was 9 months. Fifteen patients survived over two years, of whom 97% (13/15) had 1 BMF-NSCLC at presentation, and brain metastases outside the irradiated (SRS) volume appeared only in 3/15 (20%) patients [8]. In 2011, Marko et al. presented an analysis of 26 patients with asymptomatic BMF-NSCLC, treated with SRS alone. In this group, KPS was 90–100, and the mean number of brain metastases was 1.6; 40 BMF-NSCLC were irradiated in total. Mean survival was 12.3 ±4.3 months. The investigated group of patients was compared with groups of patients subject to WBRT alone (mean survival – 12.3 months), WBRT + SRS (mean survival – 12.7 months) and WBRT + surgery (mean survival – 20.2 months), matched with respect to clinical characteristics. The differences found were statistically insignificant [18].
There are numerous controversies in the literature about the role of WBRT as a treatment adjuvant to SRS [8, 35, 45–48, 54–56]. In retrospective studies Sneed et al. and Hu et al. did not find any positive effect of adjuvant WBRT on survival [54–56]. In three controlled clinical studies, the efficiency of SRS versus SRS + WBRT was evaluated [45]. Studies by Aoyama et al. [47] and Kochera et al. [46] did not show any difference in patients’ survival, but addition of WBRT statistically significantly improved local and distant (brain areas outside the SRS volume) control. The effectiveness of WBRT combined with an SRS boost used in the treatment of 1–3 brain metastases was compared with that of WBRT alone [35, 45, 51–53]. In a study of Andrews et al. (RTOG 9508), in a group of patients with single, inoperable brain metastasis, statistically significant improvement of median survival was achieved, from 4.9 to 6.9 months, after combined treatment with WBRT + SRS. In patients with 2 or 3 metastases, only improvement of local control was observed. Local control improvement, without overall survival improvement after WBRT + SRS treatment, was also found by Sanghavi et al. [50], Stafiński et al. [52] and Patil et al. in a meta-analysis presented in 2013 [53].
Many authors have reported the feasibility and efficacy of repeated SRS, as a salvage therapy, in the treatment of local recurrences of BMF-NSCLC after previous irradiation, in a highly selected group of patients [17, 35, 44, 58, 60, 61].
To conclude, SRS alone may be used in selected patients with single BMF-NSCLC, without neurological symptoms, having a good performance status (KPS – 90–100), with controlled extracranial disease. These patients need regular follow-up with frequent visits, as according to the literature 20–50% of them develop new BMF-NSCLC in regions outside the SRS volume, and they sometimes experience local recurrences that are amenable to further treatment (e.g. repeated radiotherapy or surgery) [8, 28, 30, 62]. Literature data show clearly that WBRT following SRS reduces the risk both of local relapse and of development of metastases in parts of the brain outside the SRS volume. In patients with single metastasis, addition of SRS to initial WBRT improves patients’ survival, and in patients with multiple metastases it improves local control without any effect on survival.
Whole brain radiotherapy
For several decades, WBRT combined with corticosteroid treatment has been a basic method of treatment of patients with BM-NSCLC. Whole brain radiotherapy alone is indicated primarily in patients:
with multiple BM-NSCLC,
not qualifying for surgery or SRS,
with poor performance status,
with uncontrolled extracranial disease.
Whole brain radiotherapy is also used as an adjuvant to surgery, and similarly as in the case of combination with SRS it allows for reduction of the number of brain metastasis relapses [1, 4, 15, 19, 29, 30, 35–37].
Radiotherapy doses used in WBRT range from 20 to 40 Gy, given in 5–20 fractions; the most common is the regimen administering 30 Gy in 10 fractions, and the majority of authors avoid administration of fraction doses higher than 3 Gy [30, 33, 35]. Levy et al. suggest a possibility of improvement of WBRT efficacy, in patients with single BMF-NSCLC, disqualified from surgery or SRS, by escalation of the dose to the metastatic lesion with photons from a linear accelerator [34].
Whole brain radiotherapy has a modest effect on survival of patients with BMF-NSCLC; median survival after this treatment ranges from 3 to 6 months [4, 5, 19, 28, 30, 63], and half of patients die due to progression of brain metastases [30]. 47–56% of patients respond to the treatment [4, 30, 35]. However, WBRT allows for: reduction of the dose of corticosteroids, improvement of neurological symptoms, improvement of quality of life, and survival prolongation in comparison to corticosteroid treatment alone [4, 19].
Whole brain radiotherapy vs. best supportive care
There is no doubt that there is a group of patients with BMF-NSCLC who do not benefit from WBRT and should receive only best supportive care (BSC); however, precise selection of these patients remains difficult [5, 64–66]. In a prospective study by Bezjak et al., 55% of patients with brain metastases had obvious progression or died during the first month after WBRT [64].
In a retrospective study conducted by Sundaresan et al. (2010), 23% of analysed patients with brain metastases from lung cancer died during the first 6 weeks [65]; the authors tried to develop a prognostic index for these patients with multiple brain metastases that would allow for selection of patients who would not benefit from WBRT because of a too short life expectancy. ECOG (Eastern Cooperative Oncology Group) performance status was the sole statistically significant prognostic factor.
In 2012, Craighead and Chan defined benefit from WBRT as survival of over 3 months after diagnosis of brain metastases [63]. The results of their study suggest that patients from category 2 and 3 according to RPA-RTOG (recursive partitioning analysis – Radiation Therapy Oncology Group) [67], with more than 3 metastases, do not benefit from WBRT, due to a short life expectancy (median survival 3.9 and 2.8 months, respectively) [63]. RPA-RTOG criteria are presented in Table 2, and RECIST 1.1 (Response Evaluation Criteria in Solid Tumours) response criteria for primary and metastases of the brain are presented in Table 3.
Table 2 RPA-RTOG criteria
Prognostic factors Class I Class II Class III
Age (< 65 vs. > 65 years) All good prognostic factors Other patients KPS < 70
Performance status (KPS < 70 vs. ≥ 70)
Extracranial metastases (yes vs. no)
Controlled primary (yes vs. no)
Table 3 RECIST 1.1 (Response Evaluation Criteria in Solid Tumours) – response criteria for primary and metastases of brain
RECIST 1.1. Response criteria for target lesions
Complete response (CR) Disappearance of all target lesions
Partial response (PR) At least a 30% decrease in the sum of diameters of target lesions, taking as reference the baseline sum diameters
Progressive disease (PD) At least a 20% increase in the sum of diameters of target lesions, taking as reference the smallest sum on study and at least 5 mm increase or the appearance of one or more new lesions
Stable disease (SD) Neither sufficient shrinkage to qualify for PR nor sufficient increase to qualify for PD, taking as reference the smallest sum diameters while on study
In 2013, Windsor et al. presented a group of 3459 patients subject to WBRT due to brain metastases from various cancers [5]. After WBRT, 312 (17%) out of 1800 patients with lung cancer survived 6 months or less, and 1498 (83%) survived more than 6 months. The results showed that older patients (median age – 64 vs. 61 years) and patients with a shorter interval between lung cancer diagnosis and WBRT (31 vs. 35 weeks) had worse survival; these differences were statistically significant. Concluding their study, definition of the group of patients for whom BSC is a better solution remains a challenge for investigators. In 2013, preliminary results of a controlled clinical study of the Medical Research Council, QUARTZ, were published. The study compared the results of WBRT with BSC in patients with BMF-NSCLC; 85% of patients in the WBRT group and 99% in the BSC group were in category 2 and 3 according to RPA-RTOG criteria. Preliminary results of this study showed that using BSC alone did not worsen patients’ survival or their quality of life (median survival 1.6 vs. 1.7 months) [68]. In the same year (2013) a study by Nieder et al. was published, which was similar to the QUARTZ study. In 41 patients BSC alone was used, in 41 WBRT with a dose of 30 Gy/10 fr., and in 31 WBRT with a dose of 20 Gy/5 fr.; median survival of all patients was 2.0 months, and in the groups listed above it was 1.7, 2.2 and 2.2 months respectively; the authors confirm in general the conclusions of the QUARTZ study [33].
Whole brain radiotherapy complications
Tolerance of WBRT is usually good, and early reactions are usually mild and resolve within several weeks after irradiation; they include mainly headache, fatigue, nausea and hair loss. Other early complications (≤ 6 months), in the form of a syndrome including somnolence, short-lasting memory disturbances and mild leukoencephalopathy, are also transient in nature. However, a serious problem is late complications (> 6 months after radiotherapy) that are in general irreversible, usually progressive and even life-threatening. The risk of developing the most serious of them, i.e. radiation-induced necrosis, is lower than 1% with appropriately dosed WBRT; encephalopathy occurs in 2–18% of patients, usually after 2 years following radiotherapy. Demyelination lesions and vascular damage may lead to memory, concentration and attention disturbances, mood swings, neurocognitive function (NCF) disorders and even dementia [19, 29, 35, 69]. It should be however kept in mind that many of these complications may be related to causes other than WBRT, e.g. disease progression, previous treatment (surgery, systemic treatment), anticonvulsants, patient’s age, concomitant diseases (atherosclerosis, diabetes), etc. [19, 29, 35]. Prevention of late WBRT complications includes mainly: avoidance of exceeding fraction doses of 3 Gy, hippocampal sparing radiotherapy, and use of neuroprotective agents (memantine, donepezil, lithium, renin-angiotensin system blockers, etc.) [19].
To conclude, WBRT, due to its efficacy and lack of good alternative treatment options, remains a basic treatment for patients with multiple BMF-NSCLC and poor performance status.
Summary
In summary, surgical treatment is recommended in patients with single BMF-NSCLC, with good performance status (KPS of 70 or more) and controlled extracranial disease. Patients with single (1–3) BMF-NSCLC of diameter below 33.5 cm, with no or only minor neurological symptoms, located in different regions of the brain, including those not accessible to metastasectomy, with controlled extracranial disease, are the best candidates for SRS. Whole brain radiotherapy following SRS reduces the risk of local relapse and progression of brain metastases outside the SRS volume. Whole brain radiotherapy alone, due to its efficacy and lack of good alternative treatment options, remains a basic treatment for patients with multiple BMF-NSCLC, poor performance status, with uncontrolled extracranial disease, disqualified from surgery or SRS.
The authors declare no conflict of interest.
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Contemp Oncol (Pozn)Contemp Oncol (Pozn)WOContemporary Oncology1428-25261897-4309Termedia Publishing House 2889510.5114/wo.2016.64592Review PaperMyeloid-derived suppressor cells in gliomas Gieryng Anna Kaminska Bozena Neurobiology Center, Laboratory of Molecular Neurobiology, Nencki Institute of Experimental Biology, PAS, Warsaw, PolandAddress for correspondence: Anna Gieryng, Laboratory of Molecular Neurobiology, Neurobiology Center, Nencki Institute of Experimental Biology, PAS, Pasteura 3 02-093 Warsaw, Poland. e-mail: a.gieryng@nencki.gov.pl20 12 2016 2016 20 5 345 351 27 10 2016 25 11 2016 Copyright: © 2016 Termedia Sp. z o. o.2016This is an Open Access article distributed under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International (CC BY-NC-SA 4.0) License, allowing third parties to copy and redistribute the material in any medium or format and to remix, transform, and build upon the material, provided the original work is properly cited and states its license.Myeloid-derived suppressor cells (MDSCs) are a heterogeneous population of early myeloid progenitors and precursors at different stages of differentiation into granulocytes, macrophages, and dendritic cells. Blockade of their differentiation into mature myeloid cells in cancer results in an expansion of this population. High-grade gliomas are the most common malignant tumours of the central nervous system (CNS), with a poor prognosis despite intensive radiation and chemotherapy. Histopathological and flow cytometry analyses of human and rodent experimental gliomas revealed the extensive heterogeneity of immune cells infiltrating gliomas and their microenvironment. Immune cell infiltrates consist of: resident (microglia) and peripheral macrophages, granulocytes, myeloid-derived suppressor cells, and T lymphocytes. Intratumoural density of glioma-associated MDSCs correlates positively with the histological grade of gliomas and patient’s survival. MDSCs have the ability to attract T regulatory lymphocytes to the tumour, but block the activation of tumour-reactive CD4+ T helper cells and cytotoxic CD8+ T cells. Immunomodulatory mechanisms employed by malignant gliomas pose an appalling challenge to brain tumour immunotherapy. In this mini-review we describe phenotypic and functional characteristics of MDSCs in humans and rodents, and their occurrence and potential roles in glioma progression. While understanding the complexity of immune cell interactions in the glioma microenvironment is far from being accomplished, there is significant progress that may lead to the development of immunotherapy for gliomas.
tumour microenvironmentmyeloid-derived suppressor cellsantitumor responsesimmunosuppression
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Phenotypical and molecular characteristics of myeloid-derived suppressor cells
Myeloid-derived suppressor cells (MDSCs) are a heterogeneous population of early myeloid progenitors and precursors at different stages of differentiation into granulocytes, macrophages, and dendritic cells. In healthy individuals, immature myeloid cells generated in bone marrow quickly differentiate into mature granulocytes, macrophages, or dendritic cells. Under pathological conditions such as cancer, infectious diseases, sepsis, trauma, bone marrow transplantation, or autoimmune disorders, a blockade in their differentiation into mature myeloid cells results in an expansion of this population [1]. Human MDSCs are identified as HLA-DR−CD11b+CD14−CD33+ cells that express the common myeloid marker CD33, and lack the expression of markers of mature myeloid and lymphoid cells and the MHC-class-II molecule HLA-DR [2, 3] (Fig. 1). Moreover, this heterogeneous population is composed of cells defined as CD14+ monocytic MDSC (CD11b+CD33+C14+) and CD15+ granulocytic MDSC (CD11b+CD33+CD15+CD14–) [4]. Human MDSCs commonly express Siglec-3/CD33 and lack lineage markers and HLA-DR, but heterogeneous expression of CD14 and CD15 suggests the presence of multiple subsets. Several other surface molecules have been used to identify additional subsets of MDSCs in cancer, including CD80, also known as B7.1 [5], CD115 (the macrophage colony-stimulating factor receptor), and CD124 (the IL-4 receptor α-chain) [6, 7]. Although these proteins are expressed by MDSCs, they do not define a specific MDSC population with distinct suppressive functions. Human MDSCs do not express a marker homologous to mouse Gr-1.
Fig. 1 The currently accepted phenotypic definitions of MDSCs
In humans, identification of G- and M-MDSC subsets is difficult, they have been described by the combination of several myeloid markers that, in some instances, overlap partially or completely. Additionally, a more immature subset of human MDSCs characterised by the absence of staining for the lineage cocktail (CD3–, CD14–, CD15–, CD19–, CD56–), HLA-DR−, and expression of the common myeloid markers CD33 and CD11b has been identified as an “early stage” e-MDSC, defined. Using a multi-colour staining protocol and taking into account all the reported myeloid subsets endowed with a suppressive activity, a recent study discriminated six human MDSC phenotypes: MDSC1 (CD14+IL-4Rα+), MDSC2 (CD15+IL-4Rα+), MDSC3 (Lineage−HLA-DR−CD33+), MDSC4 (CD14+HLA-DRlow/−), MDSC5 (CD11b+CD14−CD15+), and MDSC6 (CD15+FSClowSSChigh) (Table 1) [8–10]. The detection of different human MDSC phenotypes highlighted the lack of standardisation in this area and led to the establishment of a human MDSC proficiency panel according to the guidance of the Association of Cancer Immunotherapy (CIMT) Immunoguiding Program in order to promote the standardisation of MDSC immunophenotyping across different groups. The currently accepted phenotypic definitions of human MDSCs are CD11b+CD14+CD33+HLA-DR−/lowCo-receptor–/low for macrophage M-MDSCs, and CD11b+CD15+CD33+Lin–HLA-DR−/low for polymononuclear PMN-MDSCs, present in the mononuclear fraction [11]. According to the recommendations the current nomenclature of polymononuclear PMN-MDSCs, present in the mononuclear fraction, replaced former granulocytic G-MDSCs. Growing evidence shows that the phenotype and mechanisms of action of MDSCs are tumour-dependent; therefore, it is important to determine the presence of all MDSC subsets in each cancer patient [12].
Table 1 Phenotyping of human MDSC subsets with the use of multi-colour staining protocol
Human MDSCs Phenotype (multi-colour staining protocol)
MDSC1 CD14+IL-4Rα+
MDSC2 CD15+IL-4Rα+
MDSC3 Lineage–HLA-DR–CD33+
MDSC4 CD14+HLA-DRlow/–
MDSC5 Cd11b+CD14−CD15+
MDSC6 CD15–FSClowSSChigh
In mice, MDSCs are defined as CD11b+Gr-1/Ly-6G+ IL4Rα+CD11c−F4/80+/− cells [13], but the relative expression levels of Ly-6G and Ly-6C also identified two specific subsets: granulocytic (G-MDSCs) CD11b+Gr-1hiLy-6ClowLy-6G+CD49d− and monocytic (Mo-MDSCs) CD11b+Gr-1intLy-6ChiLy-6G−CD49d+ MDSCs [14–16]. Gr-1 antigen is a cell surface protein that belongs to the Ly-6 family of proteins. In rats MDSCs could be identified as CD11b+Gr-1+ cells (Fig. 2).
Fig. 2 An example of flow cytometry studies of double positive cells – CD11b+Gr-1+ from experimental C6 gliomas
MDSCs are of great interest because they have the capacity to suppress the cytotoxic activities of natural killer (NK) and NKT cells, and the adaptive immune response mediated by CD4+ and CD8+ T cells, and they induce apoptosis of T-cell subsets [17]. Multiple mechanisms responsible for MDSC-mediated T-cell suppression have been described. The two MDSC subsets inhibit immune responses through different mechanisms: PNM-MDSCs suppress antigen (Ag)-specific CD8+ T cells mainly by producing reactive oxygen species (ROS), while M-MDSCs function primarily by expressing nitric oxide synthase 2 (NOS2) and arginase 1 (ARG1), and by generating reactive nitrogen species [18]. ARG1 and NOS2 metabolise L-arginine and block translation of the T cell CD3 zeta chain, inhibit T-cell proliferation, and promote T-cell apoptosis. Moreover, MDSCs secrete immunosuppressive cytokines and induce regulatory T-cell progression. The proportions of PMN-MDSCs and M-MDSCs are variable in different tumour models. While the majority of MDSCs in peripheral lymphoid organs are PMN-MDSCs, the ratio between PMN-MDSCs and M-MDSCs is much lower at tumour sites. It has been proposed that chemokines produced by tumour cells could induce a preferential migration of M-MDSCs to the tumour site. Alternatively, special features of the tumour microenvironment such as hypoxia, low pH, and metabolic products might not support PMN-MDSC survival [18].
Normal bone marrow contains 20–30% of cells with this phenotype, but these cells constitute only a small proportion (2–4%) of spleen cells and are absent from the lymph nodes in mice. In healthy individuals, immature myeloid cells with the described above phenotype comprise ∼0.5% of peripheral blood mononuclear cells [3]. Granulocyte-macrophage colony stimulating factor (GM-CSF), granulocyte colony stimulating factor (G-CSF), and macrophage colony stimulating factor (M-CSF) are haematopoietic growth factors responsible for the recruitment, proliferation, and maturation of myeloid cells [19]. One of the main concepts of MSDC generation, the emergency myelopoiesis states that an expansion signal 1, mediated mainly by STAT3 (induced by, e.g., GM-CSF, G-CSF, and IL-6), mobilises the immature myeloid cells from the bone marrow. An activation signal 2, mediated mainly by the transcription factor NFκB (induced by pro-inflammatory stimuli, e.g. TLR signalling and cytokines), follows [20]. The concept of block in differentiation states that immature myeloid cells are arrested in their immature phase by inflammatory mediators such as S100A8, S100A9, VEGF, IL-10, and COX-2/prostaglandin PGE2 [21, 22]. The classical definition of MDSCs as immature myeloid cells blocked from terminal differentiation has been challenged by recent studies suggesting that M-MDSCs and PMN-MDSCs may represent monocytes and granulocytes that have acquired immunosuppressive properties [10]. Both emergency myelopoiesis and block in differentiation are linked to an abnormal and persistent activation of STAT3. It is believed that activation of STAT3 in myeloid progenitor cells leads to the induction of S100A8 and S100A9 expression, which subsequently acts in an autocrine manner to arrest the cells in their immature phase [23].
All MDSCs originate from common myeloid progenitors, and their development is probably governed by the same growth factors that control normal myelopoiesis, e.g. GM-CSF, G-CSF, and M-CSF. MDSC percentages increase under pathological conditions, as a result of signals released by tumour cells or chronic inflammation [24]. Emerging evidence suggests that M-MDSCs are generated by reprogramming of monocytes into M-MDSCs, whereas PMN-MDSCs might be generated from neutrophils through the activation of immature or mature granulocytes and represent different stages of activation [10].
The frequency of MDSCs positively correlates with clinical stage and tumour burden in patients with breast [25], gastric [26], and colorectal cancers [27]. Increased levels of CD14+HLA-DR–/low MDSCs were correlated with extrathoracic metastasis and poor response to chemotherapy in non-small cell lung cancer patients [28].
The analysis of ten different experimental tumour models revealed that the expansion of the PMN-MDSC population was much greater than that of the monocytic subset, and the two subpopulations used different mechanisms to suppress T-cell function. The ability to differentiate into mature DCs and macrophages in vitro has been shown to be restricted to monocytic M-MDSCs [14]. Several studies have shown that bone marrow precursor cells treated with G-CSF or GM-CSF acquire a surface phenotype similar to MDSCs found in blood of cancer patients [29–31].
Accumulation and functions of myeloid cells in gliomas
Gliomas are tumours of the central nervous system (CNS), originating from transformed neural stem or progenitor glial cells [32]. The World Health Organisation (WHO), based on histopathological characteristics, divided gliomas into groups: low-grade gliomas (grades I and II) are benign, well-differentiated, slow-growing tumours; whereas high-grade gliomas (grades III and IV) are poorly differentiated or anaplastic, rapidly proliferating, and strongly infiltrate brain parenchyma. The most frequent and malignant primary brain tumour is glioblastoma (GBM, grade IV). Histological classification is currently assisted by molecular genetic features that provide diagnostic, prognostic, and predictive values [33, 34], facilitating patient stratification, prognosis, and treatment response [35]. GBM is one of the most aggressive and difficult to treat human malignancies, due to the frequent dysfunctions of tumour suppressors or oncogenes and highly diffusive growth, which prevents tumour resection and contributes to rapid tumour recurrence [36]. GBMs show alterations in EGFR, PDGFRA, PTEN, TP53, NF1, and CDKN2A/B, TERT promoter mutations, and rarely IDH1/2 mutations (5%, mainly secondary GBMs that develop from lower grade tumours) [37, 38]. The golden standard of GBM treatment is surgery combined with chemo- and radiotherapy; however, it remains only palliative and the median survival time of adult patients with GBM is 14–15 months after diagnosis [39].
Glioma cells secrete numerous chemokines, cytokines, and growth factors that promote infiltration of various cells, including a vast majority of immune cells such as microglia, peripheral macrophages, MDSCs, leukocytes, mostly CD4+ T cells, and Treg [40–43]. These non-neoplastic cells create a specific niche within a tumour microenvironment, which plays an important role in glioma growth, metastasis, and response to treatment. Locally produced cytokines and chemokines and their crosstalk with components of the extracellular matrix re-educate infiltrating immune cells to acquire distinct functional properties, directing the immune system towards immunosuppressive responses. Like many other non-CNS malignant cancers, GBMs developed multiple strategies to inhibit host antitumour responses [44]. Several recent transcriptomic studies of GBM tissues have identified “immune and myeloid/macrophage” gene expression signatures associated with GBM pathology, overall survival (OS), or response to treatment [45–47]. These data strongly support a link between a type of the immune response, accumulation of specific immune cell subsets, and glioma progression.
Clinical studies showed extensive infiltration of gliomas with myeloid cells; the majority of them are microglia and peripheral macrophages, collectively termed glioma-associated microglia/macrophages (GAMs). Immunohistochemical studies using various markers demonstrated the higher abundance of GAMs in high-grade gliomas than in low-grade gliomas [48–51]. Application of flow cytometry allowed for more detailed analyses of myeloid subpopulations. A flow cytometry phenotype for ramified microglia isolated from adult CNS was defined as CD45lowCD11b/c+ [52–54]. Intratumoural microglia/macrophage density increases during glioma progression and correlates with the grade of malignancy [55–57]. Flow cytometry-based analyses of myeloid cells in experimental gliomas showed accumulation of polarised GAMs within the tumour microenvironment. Using flow cytometry Badie and Schartner determined the proportion of microglia (CD11b/chigh CD45low), macrophages (CD11b/chighCD45high), and lymphocytes (CD11b/c–CD45high) in rat C6, 9L, and RG-2 glioma models, and demonstrated that microglia infiltration is dependent on the glioma cell line but does not correlate with the tumour size [54]. Microglia accounted for 13–34% of the tumour mass within the tumour periphery. Macrophages represented a smaller proportion of the infiltrating cells, accounting for 5–12% of cells, and this proportion was constant in different models [54]. In the transgenic RCAS-PDGFb tumour model in which RFP–/GFP+ microglia and RFP+/GFPlow macrophages/monocytes were isolated from tumours, flow cytometry studies demonstrated 14% microglia and 8.5% macrophages/monocytes in the RCAS-PDGFb gliomas, and a similar proportion of GAMs (16% microglia and 6.5% macrophages/monocytes) was observed in GL261 tumours [58].
Immunohistochemical evaluation of functional markers and gene expression profiling of human GBM infiltrating CD11b+ cells indicate immunosuppressive activation of GAMs and point to a lack of the classical “immune response” activation in GBMs [51, 58–60]. The studies using pharmacological or genetic ablation of CD11b+ cells in experimental glioma models demonstrated that tumours do not grow and invade the brain parenchyma if GAMs are ablated or functionally paralysed [59, 61–66]. In those studies the percentages of MDSCs and their functionality were not evaluated.
Myeloid-derived suppressor cells in gliomas
The numbers of MSDCs are frequently increased in blood, spleen, and tumour mass, and they correlate with cancer stage, metastasis, and chemotherapy response [18]. Information regarding their presence and roles in gliomas is scarce [4, 67]. Gielen et al. [4] reported increased percentages of both M-MDSCs and PMN-MDSCs in the blood of GBM patients when compared with healthy donors. The myeloid activation markers B7-1/CD80 and PD-L1 were not detected, and CD124, CD86, and CD40 were detected at similar levels on MDSCs in glioma patients and healthy donors. The MDSC population in tumour cell suspensions consisted almost exclusively of CD15+ PMN-MDSC cells. Immunohistochemistry confirmed infiltration of glioma tissues with CD15+/HLAII– cells [4]. Raychaudhuri et al. reported that patients with GBM have elevated levels of MDSCs compared with age-matched healthy donors and other cancer patients. The majority of the MDSCs in GBM patients were CD15+ CD14− PMN-MDSCs (82%), followed by lineage-negative e-MDSCs (15%) and M-MDSCs (3%) [67]. Another study of 52 GBM patients revealed a significantly higher frequency of CD14highCD15+ M-MDSCs and CD14lowCD15+ PMN-MDSCs in blood of GBM patients when compared with healthy controls. Correlation between the number of PMN-MDSCs and CD4+ effector memory T-cells (CD4+ Tem) within the tumours was detected. Tumour-derived CD4+ Tem expressed high levels of PD-1 and was functionally exhausted. The expression of PD-L1 was also significantly upregulated on tumour-derived MDSCs [68]. The presented findings provide evidence for the accumulation of different MDSC subsets in GBM patients and indicate that PMN-MDSCs in peripheral blood and at the tumour site may participate in GBM-induced T-cell suppression. Accumulation of MDSCs in peripheral blood in GBM patients may induce T-cell immunosuppression, and increased plasma levels of Arginase 1 and G-CSF may contribute to MDSC suppressor function and its expansion [4].
These results are corroborated by our studies, which show a large number of Arg1+ but not Iba1+ cells (GAMs) infiltrating experimental C6 gliomas in rats [66]. Flow cytometry studies of double-positive cells – CD11b+Gr-1+ from experimental C6 gliomas (Fig. 1B) show a negligible number of such cells in normal brain and an increase of up to 3–4% in the tumour-bearing hemispheres. In addition, an increased percentage of CD11b+Gr-1+ cells was detected in the peripheral blood (5.5–6.7%) of animals implanted with glioma cells (unpublished). It confirms the increase of MDSCs in experimental rat gliomas.
Recent studies indicate that GAMs (in particular CD163+ infiltrating macrophages) within the glioma microenvironment produce Ccl2, a chemokine recruiting both Ccr2+Ly-6C+ Mo-MDSCs and Ccr4+ Treg. In murine gliomas, tumour-derived Ccl20 and osteoprotegerin induced Ccl2 production by GAMs. Gliomas developing in Ccl2-deficient mice displayed reduced Tregs and monocytic MDSCs infiltration [69]. Macrophage migration inhibitory factor (MIF), which was produced at high levels by glioma stem-like cells (CSCs), increased the expression of the arginase-1 in MDSCs in a receptor Cxcr2-dependent manner. Reduction of MIF conferred a survival advantage to tumour-bearing animals and increased the cytotoxic T cell response towards the tumour [70]. M-MDSCs of GBM patients have increased levels of intracellular S100A8/9 and serum levels compared with M-MDSCs in healthy controls. Glioma patients also have increased S100A8/9 serum levels, which correlates with increased Arginase activity in serum [71].
Antitumour immune responses in glioma microenvironment
Accumulation of GAMs and MDSCs, and their functional polarisation into pro-invasive and immunosuppressive cells, have a profound effect on antitumour responses in gliomas. The glioma microenvironment is infiltrated with leukocytes, mostly CD4+ T helper (Th), CD8+ T cytotoxic (Tc), and CD4+CD25+FoxP3+ Treg [40–42, 55, 72, 73]. The presence of CD4+CD25+FoxP3+ Treg was correlated with tumour resistance to radiation and chemotherapy, poor prognosis, and higher grade [43, 44]. Treg cells are known as suppressors of the adaptive immune response inhibiting the proliferation of effector T cells. Treg suppressive mechanism depends on the cell-cell interaction and is implicated in a host tolerance in tumour growth [55]. The tumour-infiltrating CD8+ T cells were phenotypically CD8+CD25–, suggesting that these cells were not activated. CD4+ T cells were more numerous than CD8+ T cells within glioma tissues, and the percentages of CD4+ and CD8+ cells increased with tumour grade [74, 75].
Anti-tumour immune responses mediated by T cells are suppressed by TGF-β and IL-10 secreted by glioma cells [44]. Moreover, glioma cells lack B7.1/2 (CD80/86), costimulatory and immune regulatory molecules, but constitutively express B7-H1 mRNA and protein. Glioma-related B7-H1 was identified as a strong inhibitor of CD4+ as well as CD8+ T-cell activation [75]. GBM infiltrating T-cells had decreased INF-γ production and increased PD-1 gene expression [68]. As well as directly blocking effective activation of naive T cells, glioma cells promote accumulation of Treg and MDSCs that mediate inhibition of T cells and NK cells.
Immunotherapeutic approaches for GBM, such as immune checkpoint blockade and anti-tumour vaccines, are actively tested in preclinical models and the first combinations of immunotherapies with standard therapies are being translated to clinical trials. Phase I clinical trial studying the effects of anti-PD-1 and anti-CTLA-4 combination therapy for recurrent GBM (NCT02017717), and a number of studies of DC vaccines in recurrent and newly diagnosed GBM are in progress (NCT02010606, NCT02149225, NCT02049489, NCT01808820, NCT02078648), and an entire medical community awaits results. Further understanding the biology of MDSCs and conditions for their polarisation in the tumour microenvironment and peripheral blood may be crucial for the development of new therapeutic strategies.
Acknowledgements
Studies supported by the project DIMUNO: “Development of new cancer therapies based on selective antitumor immunomodulators” – co-financed by the National Centre for Research and Development in the framework of STRATEGMED-3 Prevention practices and treatment of civilisation diseases.
The authors declare no conflict of interest.
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Contemp Oncol (Pozn)Contemp Oncol (Pozn)WOContemporary Oncology1428-25261897-4309Termedia Publishing House 2889610.5114/wo.2016.64593Review PaperSystemic treatment of non-small cell lung cancer brain metastases Cedrych Ida 1Kruczała Maksymilian A. 1Walasek Tomasz 2Jakubowicz Jerzy 3Blecharz Paweł 4Reinfuss Marian 21 Department of Systemic and Generalised Malignancies, Maria Sklodowska-Curie Memorial Cancer Centre and Institute of Oncology, Krakow Branch, Poland2 Department of Radiotherapy, Maria Sklodowska-Curie Memorial Cancer Centre and Institute of Oncology, Krakow Branch, Poland3 Department of Oncology, Maria Sklodowska-Curie Memorial Cancer Centre and Institute of Oncology, Krakow Branch, Poland4 Department of Gynecologic Oncology, Maria Sklodowska-Curie Memorial Cancer Centre and Institute of Oncology, Krakow Branch, PolandAddress for correspondence: Maksymilian A. Kruczała, Department of Systemic and Generalised Malignancies, Maria Sklodowska-Curie Memorial Cancer Centre and Institute of Oncology, Garncarska 11, 31-115 Krakow Branch, Poland. e-mail: m_kruczala@onet.pl20 12 2016 2016 20 5 352 357 02 4 2014 27 7 2015 Copyright: © 2016 Termedia Sp. z o. o.2016This is an Open Access article distributed under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International (CC BY-NC-SA 4.0) License, allowing third parties to copy and redistribute the material in any medium or format and to remix, transform, and build upon the material, provided the original work is properly cited and states its license.In the systemic treatment of brain metastases from non-small cell lung cancer (BMF-NSCLC) chemo- and targeted therapy are used. Response rates after platinum-based chemotherapy, range from 23% to 45%. Development of epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs): gefitinib or erlotinib, was an improvement in treatment of advanced NSCLC patients. EGFR mutations are present in 10–25% of NSCLC (mostly adenocarcinoma), and up to 55% in never-smoking women of East Asian descent. In the non-selected group of patients with BMF-NSCLC, the overall response rates after gefitinib or erlotinib treatment range from 10% to 38%, and the duration of response ranges from 9 to 13.5 months. In the case of present activating EGFR mutation, the response rate after EGRF-TKIs is greater than 50%, and in selected groups (adenocarcinoma, patients of Asian descent, never-smokers, asymptomatic BMF-NSCLC) even 70%. Gefitinib or erlotinib treatment improves survival of BMF-NSCLC patients with EGFR mutation in comparison to cases without the presence of this mutation. There is no data on the activity of the anti-EML4-ALK agent crizotinib. Bevacizumab, recombinant humanised monoclonal antibody anti-VEGF, in the treatment of advanced non-squamous NSCLC patients is a subject of intense research. Data from a clinical trial enrolling patients with pretreated or occult BMF-NSCLC proved that the addition of bevacizumab to various chemotherapy agents or erlotinib is a safe and efficient treatment, associated with a low incidence of CSN haemorrhages. However, the efficacy and safety of bevacizumab used for therapeutic intent, regarding active brain metastases is unknown.
breast cancerbrain metastasessystemic therapytargeted therapy
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Introduction
Between 25% and 30% of non-small cell lung cancer (NSCLC) patients will develop metastatic disease in the brain (brain metastases from non-small cell lung cancer – BMF-NSCLC). Frequently they are the first site of recurrence in early-stage NSCLC patients treated with definitive therapies [1–5]. The prognosis is poor for untreated patients with BMF-NSCLC, with median overall survival (OS) 1–2 months [1, 4, 5]. The combination of neurosurgery with stereotactic radiosurgery (SRS) and/or whole-brain radiotherapy (WBRT) can increase the OS up to 3–6 months, and in selected cases over 12 months [1, 4, 6–10].
Currently, the role of systemic treatment of BMF-NSCLC patients is being widely discussed [3, 4, 10]. Historically, chemotherapy was considered as a poorly effective method of treatment, mainly because of predicted difficulties in penetrating the blood-brain-barrier (BBB). For a long period of time, patients with BMF-NSCLC were excluded from controlled clinical trials for chemotherapy of NSCLC [1, 3, 4, 11, 12]. Nowadays it seems that even if most of the drugs cannot penetrate normal BBB, the integrity of the BBB is significantly altered, e.g. in BMF-NSCLC patients, which can be proved by oedema and increased contrast uptake around the metastatic site [12]. The significant amount of information indicates the possibility of efficient palliative systemic treatment of chosen patients with BMF-NSCLC [2, 3, 10, 11, 13]. The role of targeted therapies, besides chemotherapy, is significantly increasing [1, 4, 10, 13, 14].
The purpose of this work is to review, relying on the literature, the actual knowledge on the methods and results of systemic treatment of brain metastases from non-small cell lung cancer.
Chemotherapy
Recent phase II trials indicate efficacy, however limited, of platinum-based chemotherapy of BMF-NSCLC patients [15–20], which is presented in Table 1.
Table 1 Efficacy of platinum-based chemotherapy of BMF-NSCLC patients in phase II trials
Authors, publication date, reference no. Chemotherapy Number of patients Overall response rate (%) Median overall survival (months)
Cotto et al. 1996 [15] cisplatin + fotemustine 31 23 4
Minotti et al. 1998 [16] cisplatin + teniposide 23 35 5
Franciosi et al. 1999 [17] cisplatin + etoposide 43 30 8
Bernardo et al. 2002 [18] carboplatin, navelbine, gemcitabine 22 45 8
Cortes et al. 2003 [19] cisplatin + taxol 26 38 5
Barlesi et al. 2011 [20] cisplatin + pemetrexed 43 42 7
Phase II trials demonstrating efficacy of first-line BMF-NSCLC chemotherapy.
As outlined in Table 1, the response rates after platinum-based chemotherapy range from 23% to 45%; Chaubet-Houdu and Basse report 23–50%. Literature indicates that temozolomide (TMZ) combined with radiotherapy, in BMF-NSCLC, has a slight influence on survival, but it might increase the toxicity of the treatment [2, 11, 21–23].
Tyrosine kinase inhibitors
Development of epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs): gefitinib or erlotinib, has clearly improved the treatment of advanced NSCLC patients [3, 4, 9, 10, 13, 24–45]. EGFR mutations are present in 10–25% of NSCLC, with the highest prevalence found in never-smoking women of East Asian descent (up to 55%) [13, 24]. Paez et al. and Pao et al. found EGFR mutations to be present in 63% and 50% of BMF-NSCLC patients, respectively, which suggests increased risk of developing brain metastases among patients with these mutations [25, 26].
In a non-selected group of patients with BMF-NSCLC the overall response rates after gefitinib range from 10% to 38%, and the duration of response ranges from 9 to 13.5 months [27–30]; erlotinib has similar efficacy [31–35]. It seems that erlotinib achieves higher central nervous system (CNS) concentration in comparison to gefitinib [10, 13]. Gefitinib and erlotinib are both approved as first-line treatment, palliative treatment (second- and third-line), and in combination with radiotherapy (WBRT ± SRS), their efficacy was presented in case reports, case series, and nonrandomised phase II trials [2, 27, 31, 38, 40, 42, 45].
Two phase II trials evaluated the efficacy of TKI in the first-line setting on patients with BMF-NSCLC [38, 40]. Both trials did not include data for EGFR mutations, whereas the studies included never-smokers. Lee et al. [40] reported 10 patients; seven demonstrated an objective response to gefitinib, one had a stable disease, and two had a progressive disease after a median 48-week follow-up period. Kim et al. [38] presented a group of 23 patients with synchronous BMF-NSCLC with a response rate to gefitinib or erlotinib of 69% and median overall survival of 18.8 months. Heon et al. analysed a group of 155 patients with BMF-NSCLC screened for EGFR mutations [41]. The rate of CNS progression was lower among EGRF-mutant patients treated with gefitinib or erlotinib compared with upfront chemotherapy (patients without EGFR mutation) – 33% vs. 48%, respectively, at a median follow-up of 25 months.
Two phase II trials assessed the role of gefitinib in the palliative setting in non-selected patients with BMF-NSCLC [27, 31]. Ceresoli et al. [27] reported 41 patients with a 10% response rate and median overall survival of five months, Wu et al. [31] reported 40 patients (adenocarcinoma, never-smokers) with a 32% response rate and median overall survival of 15 months. Pesce et al. [45] in a randomised study comparing WBRT + gefitinib vs. WBRT + TMZ, failed to show an advantage of gefitinib in a non-selected group of patients with BMF-NSCLC; OS 6.3 months in the gefitinib arm and 4.9 months in the TMZ arm, the difference was statistically irrelevant.
A phase III clinical trial conducted by Sperduto et al. [2] showed that TMZ or erlotinib combined with WBRT + SRS in a non-selected group of patients with 1–3 BMP-NSCLC did not improve the OS; however, it increased the toxicity of the treatment.
Welsh et al. study [42] evaluated the efficacy of erlotinib in combination with WBRT in 40 patients with BMF-NSCLC. Patients negative for EGFR mutations had a median overall survival of 9.3 months, whereas patients positive for EGFR mutations had 19.1 months. It is also undoubted that either gefitinib or erlotinib can be safely combined with WBRT [43, 44].
Some authors suggest that in selected groups of patients with BMF-NSCLC, commencing treatment with gefitinib or erlotinib, with delayed WBRT, is acceptable. It relates to women with adenocarcinoma, never-smokers, and patients positive for EGFR mutations. Iuchi et al. presented good efficacy of gefitinib alone (without radiotherapy) in patients with adenocarcinoma BMF-NSCLC, positive for EGFR mutation – median overall survival 21.9 months in a group of 41 patients [3]. The phase II APRAGE trial, comparing WBRT + gefitinib with gefitinib alone in BMF-NSCLC patients, is ongoing [3, 12].
In conclusion, TKI (gefitinib, erlotinib) overall response rate depends essentially on the presence of EGFR gene activating mutation [10, 12, 13, 36, 37]; if mutation is present, ORR reaches more than 50% [12]. In non-selected groups of patients (adenocarcinoma, Asian descents, never-smokers, asymptomatic BMF-NSCLC) after TKIs therapy, it is possible to reach 70% ORR [13, 38]. TKIs improve survival of BMF-NSCLC patients with EGFR mutations in comparison to patients without these mutations [10, 12, 13, 39].
Crizotinib
In approximately 3–5% of patients with NSCLC, an ALK (anaplastic lymphoma kinase) rearrangement occurs. It results in forming an EML4-ALK fusion gene; it relates to mostly young, male, never-smokers, with adenocarcinoma [10, 12–14, 46]. In this group, administration of crizotinib, an anti-EML4-ALK (echinoderm microtubule-associated protein-like 4-anaplastic lymphoma kinase) drug, is reasonable and effective [10, 14, 46–48].
Kwak et al. [46] reported a 57% response rate, and a randomised phase III trial presented by Shaw et al. [47] indicated statistically relevant improvement of progression-free survival of subjects treated with crizotinib, compared to patients treated with a second-line chemotherapy (pemetrexed or docetaxel). Unfortunately, crizotinib has a poor BBB penetration, so its efficacy in BMF-NSCLC patients is doubtful [10, 13, 14, 46, 49–51]. The available literature provides poor corresponding data [12, 49, 50, 52]. Chun et al. presented a case of BMF-NSCLC progression during crizotinib treatment, despite regression of the disease outside CNS [49]. Weickhardt et al. reported on crizotinib in 38 ALK (+) patients; 28 demonstrated progressive disease, and in 46% the first site of recurrence was BMF-NSCLC. Among patients with isolated recurrence in BMF-NSCLC, treated with radiotherapy (WBRT or SRS) followed by crizotinib, progression-free survival of 7.1 months was obtained [52].
Single cases of BMF-NSCLC responsive to crizotinib were reported by Kaneda et al. [53] and Kinoshita et al. [48]. Kinoshita suggest that administering ionising radiotherapy before crizotinib treatment may play an important role in both cases [43, 48]. In 2006 Yuan et al. indicated in a murine model that CNS radiotherapy increases penetrability of the BBB [54]. Mehra et al., in a phase I trial, demonstrated responses in BMF-NSCLC patients treated with one of the new generation of ALK inhibitors – LDK 378 [55].
Bevacizumab
Bevacizumab is a humanised monoclonal antibody that binds selectively to VEGF – vascular endothelial growth factor. Blocking the VEGF protein should result in impairment of tumour blood vessel growth. Eventually, cancer cells should not develop their own blood supply, causing a lack of oxygen and nutrients, helping to slow down the growth of the tumour. Treatment of advanced NSCLC with bevacizumab remains controversial [1, 12, 13]. Results of two randomised phase III trials, ECOG 4599 and AVAil, reported that bevacizumab combined with chemotherapy improved the response rate and progression-free survival compared to chemotherapy alone in NSCLC. ECOG 4599 also reported a significantly longer OS (12.3 vs. 10.3 months) [56–58]. However, the patient population was restricted to non-squamous histology. Hypertension, massive haemoptysis, disorders in blood coagulation, and BMF-NSCLC were also qualified as exclusion criteria. The restriction of the patient population to non-squamous histology was based on the research of Johnson et al., which indicated the occurrence of life-threatening haemoptysis in this group (4/13 patients) [59]. Exclusion of BMF-NSCLC patients was based on the current opinion that bevacizumab significantly increase the risk of intracranial bleeding in this group [1, 12, 13]. In both trials, the incidence of CNS haemorrhages among patients receiving bevacizumab was similar to the incidence of those reported in patients who did not receive bevacizumab. Based on the results of these trials, bevacizumab is currently licensed for use ase first-line therapy in combination with chemotherapy (carboplatin + paclitaxel) in the USA, or in addition to platinum-based chemotherapy in Europe in patients with advanced non-squamous NSCLC [1]. However, it does not mean it is commonly used; this is because of absent or poor benefit compared to chemotherapy alone, with a slightly increased toxicity [60].
It is obvious that there are no reasons to exclude patients with brain metastases from clinical trials on antiangiogenic agents, as took place in the recent past [1, 13, 56]. Despite antiangiogenic therapy, patients with or without brain metastases have similar risk of intracranial bleeding (90.8–3.3%) [60–64].
Several retro- and prospective clinical trials conducted in the past few years indicate that the combination of bevacizumab with chemotherapy or erlotinib is safe in the treatment of BMF-NSCLC, with a slight risk of intracranial bleeding [60, 62–68].
A prospective phase IV study ARIES evaluated the safety and efficacy of the first-line setting in patients with non-squamous NSCLC treated with bevacizumab combined with chemotherapy. A total of 150 patients with BMF-NSCLC were enrolled, median PFS and OS were 6.0 and 11.7 months, respectively, and no grade 3 to 5 CNS haemorrhage occurred [65].
The phase II study PASSPORT enrolled 115 NSCLC patients with previously treated BMF-NSCLC with WBRT and/or surgery. Patients received as a first-line bevacizumab, with platinum-based doublet chemotherapy or erlotinib, and as a second-line, bevacizumab with single-agent chemotherapy or erlotinib; no grades 1 to 5 CNS haemorrhage, among patients who received bevacizumab-based therapy were reported [62].
The phase III ATLAS study was designed to evaluate the combination of bevacizumab/erlotinib versus bevacizumab/placebo as maintenance therapy after four cycles of induction platinum-containing chemotherapy plus bevacizumab as first-line treatment in advanced NSCLC patients. Among 25 evaluable patients with a history of CNS metastases pretreated with WBRT and/or neurosurgery, one grade 2 CNS bleeding was observed in a patient on post-progression therapy after 14 cycles of bevacizumab [66, 67].
The SAiL study assessed the safety and efficacy of the addition of bevacizumab to first-line chemotherapy. This study proved that bevacizumab-based therapy resulted in median OS of 14.6 months, with a median time to disease progression of 7.8 months. Efficacy was generally similar across chemotherapy regimens. The specific safety of bevacizumab was assessed in patients who either developed BMF-NSCLC during treatment or had occult BMF-NSCLC at study entry. Of the 281 patients evaluated, five (2%) had CNS bleeding [60].
The phase III BeTaLung study evaluated the addition of bevacizumab to erlotinib for the second-line treatment of advanced NSCLC patients. A total of 636 patients were randomised to receive bevacizumab in combination with either erlotinib or erlotinib alone. The addition of bevacizumab to erlotinib increased PFS compared to erlotinib alone (3.4 vs. 1.7 months, respectively). This trial included patients with BMF-NSCLC, previously treated with WBRT and neurosurgery or WBRT + SRS. Among 68 BMF-NSCLC patients, 37 received erlotinib + bevacizumab and 31 erlotinib alone. No CNS haemorrhage or grade > 3 bleeding was reported in either arm [68].
Besse et al. presented an analysis including more than 12,000 advanced/metastatic breast cancer, NSCLC, renal, and colorectal cancer patients, with previously treated CNS metastases, from 13 phase II/III randomised controlled trials, two open-label, single-arm safety studies, and two prospective studies. The rate of cerebral haemorrhage in the bevacizumab-treated group was 3.3%, compared to 1% in the group not treated with bevacizumab. This study suggests that the administration of bevacizumab should no longer be contraindicated based solely on the presence of CNS metastases [63].
Several clinical trials have been launched to determine the safety and efficacy of various other antiangiogenic agents in the treatment of new or progressive brain metastases from solid tumours: sunitinib, cediranib, and vatalanib [1].
In conclusion:
Chemotherapy is generally effective in BMF-NSCLC, and platinum-based provides response rates ranging from 23% to 45%.
Epidermal growth factor receptor tyrosine kinase inhibitors (EGFR – TKIs) – gefitinib and erlotinib – have a definite activity in BMF-NSCLC with activating EGFR mutation, or in selected groups of patients (woman of east Asian descent, never-smokers, those with adenocarcinoma); the response rate ranges from 38% to 70%. Both EGFR-TKIs have been investigated in first-line, palliative, and in combination with radiotherapy. Patients with BMF-NSCLC-EGFR-mutant have improved overall survival compared with EGFR wild-type tumours, when receiving an EGFR inhibitor.
There is no data on the activity of the agent ani-EML4-ALK-crizotinib in patients with BMF-NSCLC. Crizotinib has a poor penetration of BBB.
Data from a clinical trial enrolling patients with pretreated or occult BMF-NSCLC showed that the addition of bevacizumab to various chemotherapy agents or erlotinib is a safe and efficient treatment, associated with a low incidence of CNS haemorrhage. However, bevacizumab should be used with caution in patients with active BMF-NSCLC.
The authors declare no conflict of interest.
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Contemp Oncol (Pozn)Contemp Oncol (Pozn)WOContemporary Oncology1428-25261897-4309Termedia Publishing House 2889710.5114/wo.2016.64594Review PaperComparison of clinical pharmacology of voriconazole and posaconazole Sienkiewicz Beata M. Łapiński Łukasz Wiela-Hojeńska Anna Wroclaw Medical University, Wroclaw, PolandAddress for correspondence: Beata Sienkiewicz, Chair and Department of Clinical Pharmacology, Wroclaw Medical University, Borowska 211 A, 50-556 Wroclaw, Poland.20 12 2016 2016 20 5 365 373 24 8 2015 30 11 2015 Copyright: © 2016 Termedia Sp. z o. o.2016This is an Open Access article distributed under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International (CC BY-NC-SA 4.0) License, allowing third parties to copy and redistribute the material in any medium or format and to remix, transform, and build upon the material, provided the original work is properly cited and states its license.Despite greater knowledge and possibilities in pharmacotherapy, fungal infections remain a challenge for clinicians. As the population of immunocompromised patients and those treated for their hematologic ailments increases, the number of fungal infections grows too. This is why there is still a quest for new antifungal drugs as well as for optimization of pharmacotherapy with already registered pharmaceutics.
Voriconazole and posaconazole are broad-spectrum, new generation, triazole antifungal agents. The drugs are used in the pharmacotherapy of invasive aspergillosis, Candida and Fusarium infections. Voriconazole is also used in infections caused by Scedosporium. Posaconazole is used in the treatment of coccidioidomycosis and chromoblastomycosis. Besides some similarities, the two mentioned drugs also show differences in therapeutic indications, pharmacokinetics (mainly absorption and metabolism), frequency and severity of adverse drug reactions, drug–drug interactions and dosage. As both of the drugs are used in the treatment of invasive fungal infections in adults and children, detailed knowledge of the clinical pharmacology of antifungal agents is the main factor in pharmacotherapy optimization in treatment of fungal infections.
The goal of the article is to present and compare the clinical pharmacology of voriconazole and posaconazole as well as to point out the indications and contraindications of using the drugs, determine factors influencing their pharmacotherapy, and provide information that might be helpful in the treatment of fungal infections.
voriconazoleposaconazoleclinical pharmacologycytochrome P-450 enzyme systemdrug monitoring
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Introduction
Fungal infections are one of the most severe problems in clinical practice, especially in hematology and oncology units. They make up from 9 to 10% of all infections developing among hospitalized patients. Fungemia can be either a complication connected with the malignancy itself or an adverse effect of the oncological treatment (chemo-, radio- and corticotherapy). Furthermore, it can influence the final result of treatment. In the group of patients with oncological diseases, allogenic bone marrow transplantations, relapse of leukemia, pancytopenia lasting longer than ten days, undergoing corticotherapy and broad-spectrum antibiotic therapy, immunosuppressive treatment and graft versus host disease (GVHD) are the main factors predisposing to fungal infections. Pathogens mainly responsible for invasive fungal infections (IFI) are Candida spp. and Aspergillus spp. The first kind often develops as a concurrent illness during acute mucosa inflammation, infections connected with central venous catheters and the use of broad-spectrum antibiotics, and pre-existing colonization with the pathogen in at least one body area. The second kind leads to infection resulting from inhalation of spores from the air. This is why pulmonary aspergillosis is one of the most frequent infections caused by Aspergillus spp. (87% of patients), followed by sinusitis and rhinitis (16%), and less frequently encephalitis (8%). The risk factors of aspergillosis are neutropenia lasting for longer than two weeks, staying in an endemic region, tuberculosis and cytomegalic virus infection. The risk factors promoting fungal infections are presented in Table 1 [1–8].
Table 1 Risk factors promoting fungal infections
Factors connected with:
the patient ailments hospitalization and medical invasive procedures chemo-, radio- and corticotherapy
Born SGA (small for gestational age) Disorders of the humoral and cellmediated immunity Long-term use of central venous catheters Damage of skin and mucous membrane integrity due to chemo- and radiotherapy
Colonization with Candida fungus
Deterioration of phagocytosis and intracellular bacterial lysis Central lines Long-term use of immunosuppressive drugs
Damage of natural barriers Disorders in function of B and T lymphocytes Abdominal cavity surgery (especially repeatedly performed, and complicated) Long-term use of monoclonal antibodies
Protein and energetic insufficiency Reduction of immunoglobulin production Organ transplantation (especially liver transplantation) Long-term cortico- and antibiotic therapy
Complement system disorders Dialysis
Long-term neutropenia (> 9 days) lymphopenia, monocytopenia Parenteral nutrition
Alkalization of body fluids Colonization of skin and mucosa with hospital bacterial flora
Gastrointestinal tract passage disorders Long-term hospitalization
Bacterial infections
Necrotizing pancreatitis
Running malignant disease
The frequency of fungal infections is still growing, and the prophylactic and empiric antifungal treatment using extended spectrum drugs leads to development of resistance. Unfortunately, such infections are not easy to diagnose, especially in their early stages. This is mainly connected with their nonspecific nature – similar to virus and bacterial infections, affecting immunocompromised patients, few symptoms usually limited to pyrexia, decreased options of diagnostic testing in patients in a serious condition, and false negative results of performed diagnostic tests. It has been determined that the median mortality rate among patients, after chemotherapy, caused by invasive yeast infections is 39% and it varies among different types of fungi. As an example, the mortality rate in Aspergillus spp. infections is 49.3% and it can rise to 86.7% in patients after hematopoietic cell transplantation. For patients with candidiasis the mortality rate is about 14–36%, for invasive fusariosis it is much higher, and varies from 66 to 75%, and for scedosporiosis the estimated mortality rate is between 65 and 100% [9–11]. Every patient with neutropenia and long lasting pyrexia who is not getting better after antibiotic therapy should be suspected of fungal infection, and there is an urgent need to perform laboratory tests. Diagnostic procedures covering microscopic, microbiologic, serologic and genetic testing help to decide which pharmacological treatment would be the best [2, 3, 12].
For over 40 years, the treatment of fungal infections was based on amphotericin B. The numerous adverse effects, especially nephrotoxicity, forced scientists to search for other drugs. In the 1980s, a new generation – azole antifungal drugs – entered therapeutic use. Depending on the amount of nitrogen atoms in the azole ring, the new pharmacotherapeutic group has been divided into imidazoles (with 2 nitrogen atoms) represented by ketoconazole, miconazole, clotrimazole, tioconazole, econazole, isoconazole, and triazoles (3 nitrogen atoms) – the first generation with fluconazole and itraconazole, the second generation with voriconazole and posaconazole [13, 14].
The goal of this article is to present and compare the clinical pharmacology of the new generation triazole drugs voriconazole (approved for therapy in 2002) and posaconazole (approved for therapy in 2006) [13].
Mode of action and therapeutic indications
The mode of action of voriconazole and posaconazole is the inhibition of fungal cytochrome P450 mediated 14-alpha lanosterol demethylation, which causes damage in the structure and the loss of cell membrane function. Voriconazole is a broad spectrum antifungal agent indicated for the treatment of candidiasis also caused by fluconazole-resistant C. glabrata and C. krusei. Moreover, it can be used in Aspergillus (A. flavus, A. fumigatus, A. terreus, A. niger, A. nidulans), Cryptococcus neoformans, Fusarium, Scedosporium, Penicillium, Alternaria, Blastomyces dermatidis, Blastoschizomyces capitatus, Cladosporium, Coccidioides immitis, Conidiobolus coronatus, Madurella mycetomatis, Exserohilum rostratum, Exophiala spinifera, Fonsecaea pedrosoi, Paecilomyces lilacinus, Phialophora richardsiae, Scopulariopsis brevicaulis, and Trichosporon infections. It has a greater activity against most molds compared with amphotericin B [13–19].
The main indications for treatment with voriconazole are invasive aspergillosis (first line treatment [15, 20]), candidiasis in non-neutropenic patients, fluconazole-resistant severe invasive Candida infections (including C. krusei) and also invasive Scedosporium spp. and Fusarium spp. infections (first line treatment [20]). The drug can be used in children older than two years, and in adults. It is classified as C in the FDA Pregnancy Categorization, which means that the drug can be used in pregnant women only when the benefits for the mother outweigh the risk for the fetus. It is contraindicated during lactation [16].
In the prevention of fungal infections, no greater effectiveness of voriconazole over fluconazole has been established. A decrease in the mortality rate compared with amphotericin B treatment in the group of patients with invasive aspergillosis has been observed [18]. Voriconazole is available on the market in the form of film-coated tablets, oral suspension, and as an infusion [20]. It should be administered a minimum of 1 h before meals. A contraindication for the use of voriconazole is hypersensitivity to the drug itself or other azoles. During the treatment, liver and kidney biochemical parameters should be monitored. The patients should avoid long exposure to the sun. Photosensitivity usually develops after 12 weeks of treatment [15].
According to numerous adverse drug reactions (ADR), the duration of antifungal therapy should be as short as possible. In cases of treatment longer than 6 months, the risk-benefit balance should be considered [16].
Posaconazole is also a broad spectrum antifungal agent indicated in first line prophylaxis of invasive Aspergillus spp. and Candida spp. infections. However, its range of action is very similar to voriconazole, and so posaconazole can also be used in the treatment of Zygomycetes, Coccidioides and Chromoblastomyces infections. Cases of effective treatment of the central nervous system, pulmonary system and the treatment in cases of Ramichloridium mackenziei, Fusarium proliferatum, and Rhizopus infections have been published [21–23]. The drug is available on the market in the form of film-coated tablets, oral suspension, and as an infusion. The intravenous formulation is available in the USA, the European Union and Canada, where it has been approved by the proper medicine agencies. In contrast to the previously described voriconazole, the molecule of posaconazole has a lipophilic character which leads to differences in administration of both drugs. It was the first medicine used in patients undergoing intensive chemotherapy to induce remission. The drug was developed for prophylaxis and treatment in patients with immunodeficiency, hematological ailments and persons after bone marrow transplantation treated with high doses of immunosuppressive drugs to prevent GVHD [15, 20, 24].
Posaconazole is used in primary treatment of oral candidiasis in patients with immunodeficiency where a limited response to local treatment is expected. Other indications are pharmacotherapy and prophylaxis of invasive aspergillosis refractory to amphotericin B and itraconazole and in the case of intolerance to the first line treatment, also with voriconazole. As the second line treatment, posaconazole is used in fusariosis (in the case of intolerance to amphotericin B), chromoblastomycosis (in the case of intolerance to itraconazole), coccidioidomycosis (in the case of intolerance or refractory to amphotericin B, itraconazole and fluconazole) [24].
Unfortunately, molds resistant to posaconazole and voriconazole have already been isolated, mainly in the Candida spp. and Aspergillus spp. strains [24–26]. The main mechanism of resistance is the change of functional groups in the target protein CYP51 [15, 17, 24]. This resistance can constitute a clinically relevant problem. It has to be remembered that this is not the only mechanism of resistance to azoles, and that in fungi, always several mechanisms are involved at the same time. Apart from the lack or weakness of drug penetration resulting from changes in the composition of sterols and phospholipids in the fungal cell, changes in the efflux process of the drug, defects in the drug metabolizing cytochrome P450 enzymes and changes of the drug itself play a great role in the development of resistance.
In contrast to the bacterial one, the resistance to azoles in fungi may or may not affect cross-resistance to other drugs from the same group [27].
The main treatment indications for voriconazole and posaconazole are shown in Table 2 [16, 24].
Table 2 Main therapeutic indications for voriconazole and posaconazole
Indication Voriconazole Posaconazole
Invasive aspergillosis + (treatment) + (prophylaxis and treatment)
Candidiasis + (treatment) + (prophylaxis and treatment)
Fusariosis + (treatment) + (prophylaxis and treatment)
Scedosporium spp. infections + (treatment) –
Coccidioidomycosis – + (prophylaxis and treatment)
Chromoblastomycosis – + (prophylaxis and treatment)
Invasive fungal infections in high-risk HSCT (hematopoietic stem cell transplant) recipients including: patients with AML, and patients who have received myeloablative conditioning regimens + (prophylaxis) + (prophylaxis)
Pharmacokinetic properties and dosage regimen
The pharmacokinetics of voriconazole are non-linear in adults. The absorption is rapid and almost complete after oral administration. The maximum plasma concentration is achieved after 1–2 hours. The bioavailability is about 96%. The best absorption is achieved when voriconazole is administered twice daily in the first 24 h via the loading dose and after the first day via the maintenance dose [16, 20, 28, 29]. Lower voriconazole concentrations have been reported after oral administration, which is why careful drug monitoring needs to be performed in cases of switch from an intravenous (i.v.) to an oral formulation [30].
The distribution volume is 4.6 l/kg, which proves a good penetration of the drug into tissues. Plasma protein binding is estimated to be 58%. The drug penetrates to the cerebral fluid [16].
Voriconazole is metabolized in the liver via the CYP2C9, CYP3A4 and CYP2C19 isoenzymes, forming non-active metabolites. The genetic polymorphism of CYP2C19 isoenzyme has a great influence on inter-individual variability of pharmacokinetic parameters [16, 31]. Table 3 presents the main information about the mentioned isoenzyme, its alleles, the influence of genotype on the metabolism of voriconazole and measured serum levels. The influence of CYP2C19*9-*16 is not known yet [32].
Table 3 CYP2C19 isoenzyme and the influence of its mutations on the metabolism of voriconazole and the drug serum levels
Allele Enzymatic activity Percentage in population CYP2C19 genotype Type of metabolism Changes of serum levels after standard dose application
Caucasian Afro-American Asiatic
*2 loss 12 15 29–35 *2/*2 PM ↑
*1/*2 IM
*3 ↓ < 1 < 1 2–9 *1/*3 IM
*2/*3 PM ↑
*3/*3 PM
*4 ↓ < 1 < 1 < 1 *1/*4 IM ↑
*5 ↓ < 1 < 1 < 1 *1/*5 IM ↑
*6 ↓ < 1 < 1 < 1 *1/*6 IM ↑
*7 ↓ < 1 < 1 < 1 *1/*7 IM ↑
*8 ↓ < 1 < 1 < 1 *1/*8 IM ↑
*17 ↑ 21 16 3 *1/*17 EM ↓
*17/*17 UM
PM – poor metabolism; IM – intermediate metabolism; EM – extensive metabolism; UM – ultra rapid metabolism
The median half-life of voriconazole is approximately 6 h depending on the dose. Multiple dosing or i.v. administration increases the parameter [16].
Voriconazole is metabolized mainly in the liver; only 2% of the administered dose is excreted in an unchanged form in the urine.
There is no need of dose regimen modification according to gender. Dolton et al. suggest that there is no relation between body weight and dose requirements. However, some cases of side effects in obese patients treated with doses determined according to actual weight have been reported, whereas there have been no adverse drug reactions (ADR) if voriconazole was administered in weight-independent dosage regimens [30, 33, 34]. The dose should be elevated in children because of the more frequent inter-individual variability in the pediatric population. The i.v. way of administration is preferred in children with low body mass and absorption disturbances [16, 20].
For the adult population, no effective method of PK/PD modeling has been established, which may be associated with a limited number of data on the pharmacokinetics of voriconazole in the group of patients suffering from invasive fungal infections [35]. In adults, a loading dose of 400 mg every 12 h and a maintenance dose of 200 mg every 12 h is recommended [16]. For comparison, two pharmacokinetic models have been established for the pediatric population [35]. In the independent studies performed by Karlsson et al. and Neely et al. a loading dose of 7 mg/kg body mass for i.v. and 200 mg every 12 h for the oral formulation has been established [36, 37]. Kuo et al. stated that the best model describing the pharmacokinetics of voriconazole in the pediatric population is a linear model [38].
Posaconazole pharmacokinetics are linear, best described by a one-compartment pharmacokinetic model with first order elimination [39]. After the oral administration, the absorption of the drug depends on the dose regimen and the amount of fat in the food. The bioavailability is higher when the drug is administered in four divided doses. Co-administration with PPI (proton pump inhibitors) and metoclopramide and also inflammatory states such as mucositis reduce the bioavailability of oral posaconazole formulations [39]. After the administration of 800 mg of posaconazole in two doses, every 12 hours, the parameter is 98%; after dividing the dose into four smaller doses every 6 h it rises to 220%. The saturation of absorption has been observed after using doses above 800 mg. After a single dose administration, the time needed to reach maximal concentration (Cmax) is about 5-8 hours. The plasma protein binding level is 98%. The lipophilic posaconazole is characterized by a distribution rate of about 5–25 l/kg which suggests distribution in the extravascular space and penetration into the intracellular space [24, 40, 41]. Intravenous posaconazole formulations are well tolerated when administered in a single dose of 300 mg during 30 minutes. However, careful infusion site monitoring is recommended. The multiple dosing of posaconazole i.v. formulations leads to high rates of infusion side effects, such as thrombophlebitis [42].
Posaconazole is metabolized through the 2nd phase biotransformation, mainly by UDP-glucuronyltransferase. Only 2% of the administered dose is oxidized via the P450 cytochrome isoenzymes. The drug is a substrate and an inhibitor of P-glycoprotein. The metabolites formed by the P450 enzymes make up only a small amount of circulating metabolites [40, 41].
Posaconazole is predominantly eliminated with feces in an unchanged form (77%). Only about 14% is excreted with urine. The half-life is about 35 h, and the steady state is achieved after 5–7 days of administration [20, 24, 41].
Studies carried out in the pediatric population from 8 to 17 years of age showed a similar safety profile to the one observed in adults. Nonetheless, the number of patients was small, so there is a need for more similar studies to prove the hypothesis. In elderly patients, an increase of the Cmax and AUC (area under the curve) of about 29% was observed, what may suggest the need of dose regimen modification in this group of patients [24].
Factors influencing the pharmacokinetics
Food intake affects the bioavailability of voriconazole and decreases it by about 22%. This is considered to be an indication for administration of the drug on an empty stomach [16]. The gastric pH does not influence the solubility or absorption of the drug [43]. A second factor influencing the voriconazole pharmacokinetics is the patients’ genotype. Especially the CYP2C19 mutation previously described plays a great role. Hepatic impairment also influences the pharmacokinetics. Studies have shown 2.5-fold higher AUC values in patients with hepatic disturbances (Child-Pugh classification A and B), which suggests the need of drug regimen modification in this group of patients. An influential problem is the absence of clinical data from patients with fatal hepatic impairment. Among patients with renal failure, there is no need of drug regimen modification, but cyclodextrin, an intra-venous formulation excipient, can cumulate in the organism. The influence of this phenomenon has not been explained yet – hence caution in the use of i.v. formulations in patients with renal impairment is recommended [16, 38].
Posaconazole is better absorbed when it is administered with high fat meals in four doses of 200 mg. Its pharmacokinetics are influenced by coexistent ailments affecting the gastrointestinal motility (diarrhea, mucosa inflammation) and GVHD. Studies on healthy volunteers did not show that gender and ethnicity affect the pharmacokinetics [24, 40, 41]. It has been demonstrated that in elderly patients, the serum concentration of posaconazole is higher due to a lower apparent volume of distribution [44]. There is no need for drug regimen modification in patients with renal impairment. However, hepatic disturbances (2-fold higher γ-glutamyl transpeptidase [GGT]) and drug administration through a nasogastric tube can be an indication for dose regimen modification [14, 44].
Adverse drug reactions
Voriconazole is a well-tolerated drug. The most frequently occurring ADR are visual disturbances (23–35%) demonstrated as color vision change, blurred vision, scotoma and photophobia. These reactions appear at the time of administration and return to normal after about 30 minutes. Moreover, skin reactions such as rash (usually mild severity), gastric disturbances, hepatic disturbances (elevation of AST, ALT, alkaline phosphatase, GGT, lactate dehydrogenase, bilirubin) can appear. In about 10% of patients, abnormal heart rhythm can be observed. There have also been cases of squamous cell carcinoma with unknown etiology reported [45, 46].
Adverse drug reactions that occur more often during treatment with voriconazole than posaconazole are sinusitis, hypoglycemia, hypokalemia, depression, hallucinations, anxiety, headache and dizziness, peripheral edema, thrombophlebitis, hypotension, acute respiratory distress syndrome, pulmonary edema, jaundice, backache, acute renal failure and hematuria [14–16].
The treatment with posaconazole is often (≥ 1/100 to < 1/10) connected with the following ADR: neutropenia, electrolyte dysfunction, anorexia, paresthesia, dizziness, drowsiness, headache, vomiting, nausea, stomachache, diarrhea, dyspepsia, dry mouth, flatulence, elevated ALT, AST, alkaline phosphatase, GGT, lactate dehydrogenase, bilirubin, pyrexia, asthenia, tiredness [24].
The most frequent ADR of voriconazole and posaconazole are presented in Table 4 [16, 24].
Table 4 Most common adverse drug reactions of voriconazole and posaconazole
Adverse drug reaction Voriconazole Posaconazole
Stomach ache, nausea, vomiting, diarrhea + +
Paresthesia, somnolence, dizziness + +
Electrolyte imbalance + +
Hypoglycemia + -
AST, ALT abnormalities + +
Immune system disorders + (sinusitis) -
Rash + +
Pyrexia, asthenia + +
Psychological disturbances, depression, hallucination, anxiety + -
Peripheral edema + -
Thrombophlebitis + -
Respiratory distress + -
Renal failure + -
Visual impairment + -
Drug interactions
Voriconazole can increase serum levels of astemizole, terfenadine, cisapride, pimozide and quinidine. This leads to prolongation of the QTc and arrhythmia. The drug is also connected with the increase of sirolimus and ergot alkaloids plasma concentrations. The co-administration of the mentioned drugs with voriconazole is contraindicated. Voriconazole increases the serum levels of cyclosporine A and tacrolimus, so reduction of the dose of these drugs when co-administered is recommended. The drug increases the action of warfarin and other anticoagulants. Monitoring of prothrombin time as well as dose adjustments are needed. Monitoring of blood glucose is recommended during co-administration with sulphonylureas. The administration of voriconazole with statins may lead to rhabdomyolysis, with benzodiazepines can result in prolongation of sedative action, and with vincristine and vinblastine can result in neurotoxicity. The administration of voriconazole with an enzymatic inductor such as phenytoin and rifabutin is not recommended. The need for co-administration makes it necessary to increase the triazole maintenance dose. Monitoring of methadone adverse drug reactions is recommended. Posaconazole co-administered with ergot alkaloids may lead to prolongation of QTc. The drug is one of the CYP3A4 inhibitors, which creates a need for dose adjustment in co-administration with many other drugs [14, 16, 24, 28].
In Table 5 voriconazole and posaconazole drug interactions leading to changes in plasma concentrations of antifungal agents are presented [16, 24, 28].
Table 5 Voriconazole and posaconazole drug interactions
Antifungal agent Drugs and other substances decreasing antifungal agent serum levels Drugs and other substances increasing antifungal agent serum levels
Voriconazole Rifampicin, rifabutin, carbamazepine, phenytoin, delavirdine, efavirenz, nevirapine, ritonavir, amprenavir, darunavir, phenobarbital, mephobarbital, hexobarbital, pentobarbital, secobarbital, butabarbital Cimetidine, fluconazole, omeprazole, oral contraceptives
Posaconazole Phenytoin, cimetidine, famotidine, ranitidine, esomeprazole, lansoprazole, omeprazole, pantoprazole, metoclopramide, rifabutin, efavirenz, fosamprenavir Posaconazole, as an enzymatic inhibitor, mainly increases the plasma concentrations of other drugs such as: quinidine, pimozide, astemizole, terfenadine, midazolam, amlodipine, diltiazem, felodipine, nifedipine, nitrendipine, verapamil, dihydroergotamine, ergotamine, methysergide, cyclosporine A, sirolimus, tacrolimus, cisapride, atorvastatin, lovastatin, simvastatin, vinblastine, vincristine, vinorelbine
The main drug interactions and recommendations for co-administration of voriconazole and posaconazole with other drugs are demonstrated in Table 6 [16, 24].
Table 6 Comparison of therapeutic recommendations for co-administration of voriconazole and posaconazole with other drugs
Drug Therapeutic recommendations for co-administration of
voriconazole posaconazole
Astemizole, pimozide, quinidine, terfenadine Contraindicated Contraindicated
Efavirenz Contraindicated in standard doses – need for modification Should be avoided unless the benefit outweighs the risk
Rifabutin Should be avoided unless the benefit outweighs the risk Should be avoided unless the benefit outweighs the risk
Phenytoin Should be avoided unless the benefit outweighs the risk Should be avoided unless the benefit outweighs the risk
Cimetidine No contraindications Avoid combined therapy
Omeprazole Dose adjustment to 20 mg Avoid combined therapy
Statins Dose adjustment Contraindicated
Vinca alkaloids Dose adjustment Should be avoided unless the benefit outweighs the risk.
Sirolimus Contraindicated Should be avoided unless the benefit outweighs the risk.
Cyclosporine A, tacrolimus Careful monitoring for any occurrence of drug toxicity and/or lack of efficacy, and dose adjustment may be needed Careful monitoring for any occurrence of drug toxicity and/or lack of efficacy, and dose adjustment may be needed
HIV protease inhibitors Careful monitoring for any occurrence of drug toxicity and/or lack of efficacy, and dose adjustment may be needed Careful monitoring for any occurrence of drug toxicity and/or lack of efficacy, and dose adjustment may be needed
Benzodiazepines Dose adjustment Dose adjustment
Digoxin No contraindications Careful monitoring for any occurrence of drug toxicity and/or lack of efficacy, and dose adjustment may be needed
Sulphonylureas Careful monitoring of blood glucose is recommended Careful monitoring of blood glucose is recommended
Therapeutic drug monitoring of voriconazole and posaconazole
According to the pharmacokinetics of voriconazole and posaconazole, adverse drug reactions and other factors influencing the serum levels, therapeutic drug monitoring (TDM) is required for optimization of treatment of invasive fungal infections, but there is only a limited amount of research on the topic. Brüggemann et al. state in their article the urgent need for TDM enrollment, and point out the areas with lack of information [47]. The study carried out by Soler-Palacín et al. suggested the need for inclusion of therapeutic drug monitoring in the routine procedures among the pediatric population [48]. In the case of posaconazole treatment, TDM is needed only in high-risk patients, to determine compliance [49–51]. The British Society for Medical Mycology laid down guidelines for TDM of antifungal agents. According to the publication, “therapeutic drug monitoring should be performed in the majority of patients receiving voriconazole or posaconazole” [52].
In Table 7, the most important information connected to TDM of antifungal agents is presented [28, 44].
Table 7 Therapeutic drug monitoring of voriconazole and posaconazole
Antifungal agent Indication for serum level monitoring Time of first serum level detection (days) Minimal concentration (µg/ml)
Effectiveness Safety
Voriconazole Young age, no treatment response, gastrointestinal disorders, hepatobiliary disorders, neurological disorders, other drugs co-administration, IV to p.o. switch, long-term therapy 4–7 Prophylaxis > 0.5
Therapy > 1 to 2 < 6
Posaconazole Older age, no response to the therapy, gastrointestinal disorders, hepatobiliary disorders, other drugs, gavage, GVHD > 7 Prophylaxis > 0.7
Therapy > 0.7 to 1.250 Has not been determined
In conclusion, among numerous similarities, the clinical pharmacology of voriconazole and posaconazole exhibits some differences as well, as demonstrated in this article. It is necessary to take them into consideration in everyday clinical praxis. Table 8 is a summary of all similarities and differences between the two drugs discussed in this article [16, 20, 24, 35].
Table 8 Comparison of clinical pharmacology of voriconazole and posaconazole
Variable Voriconazole Posaconazole
Similarities
Drug family Triazole antifungal drugs
Method of administration p.o., i.v.
Effectiveness in treatment of Invasive aspergillosis, fusariosis, candidiasis
Safety Narrow therapeutic index (recommendation for TDM)
Differences
Additional effectiveness against
Scedosporium spp. Coccidioides, chromoblastomycosis
Dosage recommendations Two doses per day; in the first 24 h – loading dose, during next days – maintenance dose Four doses for p.o. formulations, single dose for i.v. formulations
Pharmacokinetics Non-linear in adults, linear in children Linear
Bioavailability > 95% Depending on the dosage regimen and food intake
Absorption Decreased by high fat meals intake Increased by high fat meals intake
Protein binding (%) 58 > 98
Distribution ratio (l/kg) 4.6 7–25
Steady state after (days) 5–6 7–10
Maximal time (h) 1–2 3–6
Metabolism isoenzymes P-glycoprotein, UDP-glucuronyltransferase
Mainly through phase I reaction phase II reaction
Half-life (h) 6–12 15–35
Elimination hepatic, < 2% unchanged eliminated with urine 66% of unchanged drug eliminated with feces, < 1% eliminated with urine
The authors declare no conflict of interest.
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Contemp Oncol (Pozn)Contemp Oncol (Pozn)WOContemporary Oncology1428-25261897-4309Termedia Publishing House 2889810.5114/wo.2016.64596Original PaperDetermining the potential of desmoglein 3 as a sensitive and specific immunohistochemical marker for the detection of micrometastasis in patients with primary oral squamous cell carcinoma Nagvekar Shruti Spadigam Anita Dhupar Anita Department of Oral and Maxillofacial Pathology, Goa Dental College and Hospital, Bambolim-Goa, IndiaAddress for correspondence: Shruti Nagvekar, Department of Oral and Maxillofacial Pathology, Goa Dental College and Hospital, Bambolim-Goa, India. e-mail: shrutinagvekar123@gmail.com20 12 2016 2016 20 5 374 380 23 2 2016 22 6 2016 Copyright: © 2016 Termedia Sp. z o. o.2016This is an Open Access article distributed under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International (CC BY-NC-SA 4.0) License, allowing third parties to copy and redistribute the material in any medium or format and to remix, transform, and build upon the material, provided the original work is properly cited and states its license.Aim of the study
Despite advances in surgical and radiotherapy techniques, the presence of lymph node metastasis drastically decreases the survival rate of patients with primary oral squamous cell carcinoma (OSCC). Thus the accurate pathological staging of the neck is critical. Desmoglein 3 (DSG3), a desmosomal cadherin protein is said to be highly expressed in head and neck squamous cell carcinoma (HNSCC) and in metastatic cervical lymph nodes, but absent in non-invaded nodes. With an aim to improve the sensitivity of tumour cell detection, we investigated the potential of DSG3 as an immunohistochemical marker for the detection of occult lymph node metastasis in patients with primary OSCC.
Material and methods
Forty-seven lymph node specimens from 10 patients who underwent neck dissection for primary OSCC were immunostained with DSG3.
Results
The DSG3 positivity was noted in the six positive lymph nodes. However, when using DSG3 as an immunohistochemical marker, no additional micrometastatic deposits were evident in the histologically negative nodes. Interestingly, tumour marker DSG3-positive macrophages could be identified within the subcapsular sinuses, medullary sinuses, and the interfollicular areas.
Conclusions
Our findings suggest that although DSG3 is overexpressed in HNSCC, it is not specific and may not prove to be a potent immunohistochemical marker to detect micrometastasis. The role of tumour marker-positive macrophages within the lymph nodes needs to be investigated further.
desmoglein 3micrometastasisM2 phenotypetumour markerpositive macrophages
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Introduction
Head and neck squamous cell carcinoma (HNSCC) accounts for 6% of all cancer cases and ranks sixth with regards to cancer related deaths [1]. About 40–50% of the cases with advanced disease (stage III and IV) recur, and approximately 80% of recurrences occur within the first two years. One reason for the high mortality associated with late stage HNSCC is the inherent capability of tumour cells to undergo locoregional invasion due to the presence of a rich lymphatic network and the overall high number of lymph nodes in the neck region [2]. Thus early and accurate detection of metastatic disease is of paramount importance.
A good marker for the detection of lymph node metastasis should show marked variation in its expression in the positive and negative lymph nodes [3]. Cytokeratins have been widely used for the detection of nodal metastasis; however, variability in their expression has been observed [4].
Desmoglein 3 (DSG3) is a calcium-binding trans-membrane glycoprotein (130 kDa) component of desmosomes, which forms button-like points of intercellular contacts [5]. Desmosomal cadherins: desmogleins and desmocollins, mediate cell-cell adhesion by coupling to keratin intermediate filaments through the adaptor proteins plakoglobin, plakophilin, and desmoplakin [6]. Desmosomal proteins, including DSG3 serve as signalling centres. Over-expression of DSG2 or DSG3 has also been demonstrated in skin and head neck cancer. The importance of DSG3 as a novel molecular target for the early detection, prevention, and treatment of HNSCC was demonstrated in the higher expression of DSG3 in the proteomic analysis of HNSCC lesions by Patel et al. (2008) [7].
The correlation of DSG3 with regional lymph node metastasis may be explained on a cellular level by the role of DSG3 in the regulation of cell migration and invasion. Alteration in desmosome composition results in an alteration in signal transduction, resulting in increased transformation. There is supportive evidence showing that DSG3, as an up-stream regulator of Src activity, helps regulate adherens junction formation [8]. Moreover, overexpression of DSG3 results in the formation of filopodial protrusions and increased cell migration [9].
In 2013, Patel et al. identified DSG3, from amongst an array of other markers, to be a squamous-specific protein marker expressed specifically in the positive lymph nodes and a potential marker for detecting micrometastatic deposits [7]. This study tested the potential of DSG3 for the detection of micrometastasis in the cervical lymph nodes of patients with primary HNSCC.
Material and methods
Patients and samples
Forty-seven archival formalin-fixed paraffin-embedded specimens from 10 patients who underwent ipsilateral lymph node dissection for OSCC from 2011 to 2014 were retrieved from the archives of the Department of Oral and Maxillofacial Pathology, Goa Dental College & Hospital, India. Data on gender, age, stage of disease, and histopathological factors was obtained from the medical records and was analysed.
Haematoxylin & eosin staining and re-evaluation
In order to confirm the diagnosis of the 47 archival tissue specimens, new sections were made for each selected tissue block using a Leica RM2125 RTS soft tissue rotary microtome. Section thickness was kept uniform at 3 µm. The slides were stained with standard Harris haematoxylin and 1% eosin Y staining protocol. The lymph node specimens were re-evaluated to check for the presence of metastatic deposits before the immunohistochemical analysis was performed. On evaluation, 41 out of 47 were confirmed to be negative whereas 6 were positive.
Immunohistochemistry
Forty-seven lymph node specimens along with one positive control (normal oral mucosa) and one negative control (normal oral mucosa not subjected to primary antibody) were subjected to immunohistochemical examination. Immunophenotypical analysis was performed by the standardised Envision™ method employing 3-µm thick, formalin fixed, paraffin embedded sections using a commercially available mouse monoclonal antibody (Abcam Monoclonal Mouse Anti-Human Desmoglein 3 Antibody Clone ab14416 used at a concentration of 5 µg/ml) directed against the extracellular domain of DSG3. This antibody does not cross-react with desmoglein 1 or desmoglein-2 protein.
Heat-induced epitope retrieval was performed with the help of DAKO PTLink™ using the ‘3 in 1 DAKO Target Retrieval Solution’ (used at a dilution of 20×). The endogenous peroxidase activity was blocked by using the EnVision™ FLEX Peroxidase Blocking Reagent for 5 minutes. The primary antibody was then incubated for 30 minutes at room temperature after dilution in the DAKO EnVision™ FLEX Antibody Diluent (5 µg/ml), followed by a rinse with DAKO wash buffer solution. 100 µl of EnVision™ FLEX Horseradish Peroxidase (HRP) was then dispensed on each slide and incubated for 10 minutes, followed by a rinse with wash buffer. Finally, 100 µl of DAB chromogen (EnVision™ DAB-Dako Chromogen System) was applied to each section and incubated for 3–10 minutes. Samples were then rinsed with distilled water, counterstained with Mayer’s haematoxylin, dehydrated, and mounted. Negative controls were prepared by substituting wash buffer solution for the primary antibodies.
Reading
Slides (H&E stain and DSG3 stain) were reviewed with light microscopy. The presence of immunoreactive cells, morphologically consistent with cancer cells within the substance of the lymph nodes were evaluated. The term “Micrometastasis” was used to refer to occult metastatic deposits within the lymph nodes, in which the tumour cell aggregate ranged in size between 0.2 mm and 2 mm, and “Isolated tumour cells” referred to tumour deposits < 0.2 mm.
Statistical analysis
Comparison of findings on routine histological and those on immunohistochemical examination was done using McNemar’s test. To validate the data, correlation between the incidence of metastasis and the size and level of lymph nodes was confirmed using Fisher’s exact χ2 test (level of validity was determined as p < 0.05).
Results
Clinical
The gender distribution was six males and four females (Table 1). The age of patients at the time of surgery ranged from 44 to 73 years, and mean age was found to be 60.10 years. Patients most frequently presented with a lesion in the buccal vestibule.
Table 1 Gender demographics of OSCC patients
Gender Frequency Percentage (%)
Males 6 60.0
Females 4 40.0
Pathological features
The size of the primary tumour ranged from 0.5 cm to 6 cm in maximum dimension, with a mean of 3.75 cm and standard deviation of 1.84. Among the 10 cases of OSCC evaluated, seven were of well differentiated type, two cases were of moderately differentiated type, and one case was of poorly differentiated type. Of the total 47 lymph nodes studied on routine histopathology, 41 were negative whereas 6 were positive for metastasis (Figs. 1 and 2). Two of the total 6 cases of metastases occurred in the nodes 20 to 25 mm in size and two in > 25 mm sized lymph nodes.
Fig. 1 Haematoxylin and eosin-stained section of a negative lymph node specimen (H&E, original magnification 40×)
Fig. 2 Haematoxylin and eosin-stained section of a positive lymph node specimen demonstrating tumour deposits (H&E, original magnification 100×)
The relation between metastasis with the size of lymph nodes was evaluated using Fisher’s exact χ2 test (Table 2). A statistically significant difference (p = 0.003) in the incidence rate of metastasis due to the size of lymph node was noted in comparison with different sized lymph nodes. In analysing the level of the lymph nodes with metastasis, it was found that two of the total six cases of metastasis occurred in level IB lymph nodes. Fisher’s exact χ2 test showed a statistically significant difference (p = 0.006) in the incidence rate of metastasis with the level of the lymph nodes (Table 3). Although a statistically significant difference was observed between the incidence of metastasis and the size and level of lymph nodes, an accurate interpretation of the results would be based on evaluation of a large number of lymph nodes.
Table 2 Distribution of metastasis with the size of lymph nodes
Size (mm) Number of nodes Number of positive nodes (H&E) Percentage of metastasis Fisher’s exact χ2 test
0–5 3 0 0 p = 0.003
5–10 18 0 0
10–15 17 1 5.9
15–20 3 1 33.3
20–25 2 2 100
> 25 4 2 50
Table 3 Distribution of metastasis with the level of lymph nodes
Valid Frequency Percentage Valid Percentage Number of positive nodes (H&E) Percentage Fisher’s exact χ2 test
I A 6 12.8 12.8 1 16.7 p = 0.006
I B 2 4.3 4.3 2 100
II A 9 19.1 19.1 1 11.1
II B 11 23.4 23.4 0 0
III 17 36.2 36.2 1 5.9
IV 2 4.3 4.3 1 50
Total 47 100.0 100.0 6 12.8
A well-defined intercellular staining pattern was observed in the positive control (oral mucosa) (Fig. 3). DSG3 positivity was noted in the metastatic deposits, and no additional micrometastatic deposits could be detected in the histologically proven negative nodes. The data was analysed using McNemar’s test and was found to be statistically non-significant (p = 1.000). These results are summarised in Table 4.
Table 4 Comparison of findings on routine histological examination and those on immunohistochemical evaluation
Method Detection Total McNemar’s test
Negative Positive
IHC Count 41 6 47 p = 1.000
% within method 100% 100.0%
% of total 87.2% 12.8%
H&E Count 41 6 47
% within method 100% 100.0%
% of total 87.2% 12.8%
Fig. 3 Positive control: Stratified squamous epithelium of the oral mucosa: DSG3 positivity seen in the intercellular junctions (DSG3, original magnification 400×)
There was difficulty in identifying additional micrometastatic deposits due to the presence of a substantial number of activated macrophages that exhibited DSG3 immunoreactivity. The DSG3+ macrophages were found in the subcapsular sinuses, interfollicular areas, medullary sinuses, as well as in the lymphoid follicles. To confirm whether the DSG3+ cells were indeed macrophages and to evaluate its polarisation, the specimens were then subjected to the following markers: CD68 (pan macrophage marker) and CD163 (marker for M2 phenotype). The DSG3+ cells were CD68+, thus confirming the macrophage phenotype of the cells. However, a subset of the group were CD163+, confirming the M2 polarisation of the macrophages (Figs. 4–6).
Fig. 4 Photomicrograph revealing CD68 positive cells within the subcapsular sinus indicative of macrophages (CD68, original magnification 100×). (Inset: 400×)
Fig. 5 Photomicrograph revealing DGS3 positive macrophages within the lymph nodes (DSG3, original magnification 100×). (Inset: 400×)
Fig. 6 Photomicrograph revealing CD163 positive macrophages within the lymph nodes (CD163, original magnification 100×) (Inset: 400×)
Discussion
The five-year survival rate of patients largely depends on the tumour stage at the time of diagnosis, decreasing from 50% in patients without the presence of lymph node metastasis to 90% with nodal metastasis [10–12]. Approximately 30% of patients with OSCC, who present without any clinical or radiographic evidence of regional disease, in fact harbour occult cervical metastasis, which is detected microscopically – divided into three types: macrometastases (> 2–3 mm in the largest dimension), micrometastases (< 2–3 mm in the largest dimension), and isolated tumour cells (individual or small clusters of tumour cells within the lymph node sinuses < 0.2 mm). The size and type of metastasis may influence the prognostic value of nodal metastases [12, 13]. Thus detection of tumour deposits within the lymph nodes is critical for patient care.
Immunohistochemistry serves as a reasonably good cost-effective alternative over PCR immunoarrays in the detection of occult lymph node metastasis. Although cytokeratins have been consistently used as immunohistochemical markers for detection of nodal metastases, they are not very specific. Reticulum cells, ectopic salivary gland inclusions, mesothelial inclusions, and metastatic thyroid follicles can show cytokeratin positivity [12, 14]. Several studies have also found inconsistencies in the precise cytokeratin to be analysed [7].
Chen et al. surveyed and identified several cancer-associated genes using differential display and showed that DSG3 is overexpressed in head and neck cancer, with the degree of overexpression associated with the clinic-pathologic features of the tumour [5].
Several other studies have shown that DSG3 is a squamous specific marker and highly expressed in head and neck carcinoma [6, 15–17]. Thus in a quest to find a single specific and sensitive marker and thus to enhance the detection of micrometastatic disease, we investigated the potential of DSG3 as a marker for the detection of occult metastasis.
In the current study, we could not detect any additional micrometastatic deposits in the 41 histologically evaluated negative nodes. Using cytokeratins as markers of micrometastasis detection in HNSCC cases, various authors have shown that the detection rate varies from 1.3% to 68% [4, 12, 18]. Patel et al. [7] evaluated formalin-fixed, paraffin-embedded, anonymised tissue sections of non-metastatic (N0) and metastatic (N+) human cervical lymph node biopsies from patients diagnosed with HNSCC for expression of DSG3 and cytokeratin. Positive lymph nodes (n = 30) stained positive for CK+ and DSG3+ whereas negative lymph nodes (n = 5) were CK– and DSG3–. They then tested the usefulness of DSG3 to be used as a sensitive marker using the microfluidic immunoarray system. Protein extracts of normal and positive metastatic lymph nodes were used for the same. The negative lymph nodes showed marginal values for DSG3, which was attributed to nonspecific binding, whereas all of the positive, metastatic lymph nodes showed high levels of DSG3 protein expression [7].
This is the only study conducted in subsequence of the study presented by Patel et al. evaluating the efficacy of DSG3 as a marker for the detection of micrometastasis in cervical lymph nodes. In contrast to their study, we did not detect any occult metastatic deposits with IHC. Interestingly, a substantial number of activated macrophages showing positivity for DSG3 could be identified within the subcapsular sinuses, interfollicular areas, and medullary sinuses as well as in the lymphoid follicles and exhibited characteristic granular to diffuse cytoplasmic staining patterns. The study of Patel et al. [7] did not report this finding. The presence of the DSG3+ cells posed diagnostic difficulty in differentiating the isolated tumour cell deposits from the activated macrophages, thus reducing the specificity of the marker. However, DSG3 characteristically highlighted the macro-metastatic deposits. To further confirm the phenotype of the DSG3+ cells within the histologically negative lymph nodes, the tissue sections were subjected to CD68 and CD163 antibodies/markers. It was seen that these DSG3+ macrophages were CD68+ (confirming the macrophage phenotype), and a subset of these macrophages showed CD163+ positivity (M2 polarisation).
Macrophages are pivotal members of the inflammatory infiltrate and respond to the microenvironment signals [19]. Evidence suggests that macrophages support tumour-associated angiogenesis, promote tumour cell invasion, facilitate tumour metastasis, and suppress antitumour immune responses [20]. Recent studies have further strengthened the idea that through interaction between tumour cells and macrophages, macrophages undergo a process of “education” within the tumour microenvironment [19]. As such they can be polarised into two functionally distinct states: Classically activated (M1) state, which possesses anti-tumour activity; and the alternatively activated (M2) state, which promotes tumour invasion and metastasis [21]. Most tumour associated macrophages (TAMS) are M2 type, which are recognised by CD163 positivity immunohistochemically. CD68 is used as a pan-macrophage marker [21].
Owing to the compromised phagocytic activity, the M2 macrophages contribute to the phenomenon of immune evasion of the tumour cells invading the lymph nodes. Oberg et al. (2002) showed that poor patient survival correlates with the number of M2 macrophages [22].
Wehrhan et al., on evaluation of the macrophage polarisation in patients with OSCC, observed that the lymph vessel infiltration at the primary site was associated with M2 polarisation of the macrophages in the regional lymph nodes. These M2 macrophages were thought to contribute to the peripheral immune tolerance [22].
Various other studies on malignant melanoma, colon carcinoma, and prostate carcinoma have demonstrated the presence of tumour marker-positive macrophages in the regional lymph nodes [23, 24]. Japink et al. postulated that the activated macrophages are attracted to the tumour stroma and find themselves in close proximity to the damaged tissue. This tumour antigen is then engulfed and concentrated within the TAMs [25]. Direct communication between macrophages and tumour cells is said to prepare the regional lymph nodes for the acceptance and sustenance of metastases [22, 26].
Faber et al., from the assessment of regional lymph nodes from patients with primary colon carcinoma, concluded that tumour marker-containing macrophages travel via the lymphatic system towards the regional lymph nodes [24]. They also found substantial differences between the expression of the various tested tumour markers (CEA showing the greatest expression in comparison to M30 and cytokeratin). They attributed the variable expression of the markers to the following:
The stability of the tested substance. CEA, being an extremely stable molecule, can survive adverse processing conditions, whereas cytokeratins are easily damaged by electrical or chemical agents.
There could be a relation between the presence and the distribution of the investigated substances in the tumour and the possibility of finding loaded macrophages [24].
Desmosomes are highly insoluble structures and can withstand harsh denaturing conditions, thus having a higher probability of being detected within the TAMS [27–29]. Also, the substances a macrophage encounters may depend on the macrophage and its location. The differences described above may explain why not all macrophages of the lymph nodes contain the same substance/antigen and also not the same amount [7, 24, 30].
Pawelek postulated that the fusion of tumour cells with bone marrow-derived cells as a possible explanation for tumour progression and metastasis. Such hybrid cells have been identified in vitro and in sporadic cases in vivo [31]. They proposed a simple model to explain a unifying concept of metastasis: “White blood cell + Cancer cell = Cancer cell with metastatic potential” [31].
In one of the first experiments, Pawelek experimentally fused normal mouse or human macrophages with mouse Cloudman S91 melanoma cells that had weak metastatic potential. They observed that the hybrid clones showed markedly enhanced chemotactic motility, and when implanted in mice, these hybrids showed elevated metastatic potential compared to the implanted parental Cloudman S91 melanoma cells [31].
Desmoglein 3 and CD68 positivity within the macrophages might lead us to believe that these cells could represent tumour cell-macrophage hybrid models.
In conclusion, the present study concludes that DSG3 cannot be used as a single and specific immunohistochemical marker for the detection of micrometasis and may not prove to be a better marker than cytokeratins. DSG3 stains macrophages and does not appear to provide a confident interpretation of metastasis where isolated positive cells or micrometastatic deposits are involved.
However, the most interesting finding of the study was the presence of the tumour marker positive macrophages. Although the concept of tumour marker-positive macrophages has not been studied or investigated in HNSCC, there have been studies done in colon carcinoma, breast cancer, and malignant melanoma cases. The significance of their detection is still under research.
We propose the following theories to explain the presence of tumour marker-positive macrophages within regional lymph nodes. Firstly, it could be that the macrophages have engulfed the tumour antigen and migrated towards the lymph nodes. This could be related to creating an environment conducive for the acceptance of tumour deposits. Desmogleins, being stable structures in comparison to cytokeratins, are better preserved following staining procedures, thus increasing the possibility of their detection within the macrophages. Secondly, the tumour marker-positive macrophages could be a form of tumour cell-macrophage hybrid.
Further investigation into the role of the tumour marker-positive macrophages (especially the M2 polarised type) within the lymph nodes, could help to better devise molecular therapies targeted at restricting the spread of tumour cells at an earlier stage.
The authors declare no conflict of interest.
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Contemp Oncol (Pozn)Contemp Oncol (Pozn)WOContemporary Oncology1428-25261897-4309Termedia Publishing House 2889910.5114/wo.2016.64597Original PaperTreatment related toxicity in BRCA1-associated epithelial ovarian cancer – is DNA repairing impairment associated with more adverse events? Badora-Rybicka Agnieszka 1Budryk Magdalena 2Nowara Elżbieta 1Starzyczny-Słota Danuta 11 Clinical and Experimental Oncology Department, Maria Skłodowska-Curie Memorial Cancer Center and Institute of Oncology, Gliwice Branch, Poland2 Genetic Outpatient Clinic, Maria Skłodowska-Curie Memorial Cancer Center and Institute of Oncology, Gliwice Branch, PolandAddress for correspondence: Agnieszka Badora-Rybicka, Clinical and Experimental Oncology Department, Maria Skłodowska-Curie Memorial Cancer, Center and Institute of Oncology, Gliwice Branch, Wybrzeże Armii Krajowej 15, 44-101 Gliwice, Poland. e-mail: agnieszka.k.badora@gmail.com20 12 2016 2016 20 5 381 384 03 1 2016 14 3 2016 Copyright: © 2016 Termedia Sp. z o. o.2016This is an Open Access article distributed under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International (CC BY-NC-SA 4.0) License, allowing third parties to copy and redistribute the material in any medium or format and to remix, transform, and build upon the material, provided the original work is properly cited and states its license.Aim of the study
The presence of BRCA germline mutations in patients with ovarian cancer has been shown to have predictive and prognostic significance, including increased platinum-sensitivity. The aim of the study was to evaluate if patients with BRCA1-associated ovarian cancer have more treatment related adverse events and, if so, does it have impact on chemotherapy outcomes.
Material and methods
We conducted a retrospective analysis of medical records of 172 patients with newly diagnosed epithelial ovarian cancer, treated in Maria Skłodowska-Curie Memorial Cancer Center and Institute of Oncology, Gliwice Branch between 2007 and 2013. Ninety-six of these patients have known BRCA mutation status – 21 patients were BRCA1(+) and 75 BRCA1(–). Analysed treatment related adverse events (AE’s) were: haematological toxicity, nausea/vomiting, neuropathy and mucositis.
Results
Grade 3–4 haematological AE’s were significantly more common among BRCA1(+) patients (OR = 3.86; 95% CI: 1.14–13.23; p = 0.02). There was no association between BRCA1 mutation status and neuropathy (p = 0.73) or nausea/vomiting (p = 0.91). Occurrence of above mentioned AE’s has no significant association with PFS (p = 0.75, 0.64, 0.97 respectively) and OS (p = 0.64, 0.69, 0.73 respectively).
Conclusions
Among patients with BRCA1-associated epithelial ovarian cancer we observed significantly more grade 3–4 haematological complications after chemotherapy. However, occurrence of AE’s did not correlate with better outcomes in this subgroup.
BRCA1ovarian canceradverse events
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Introduction
BRCA1 or BRCA2 germline mutation carriers account for 10–15% of epithelial ovarian cancer cases [1–3]. BRCA-associated ovarian cancers are usually of serous histology and, in comparison to sporadic ones, of higher grade, more advanced and diagnosed at a younger age [4].
BRCA1 and BRCA2 genes are considered tumor suppressor, since they play important role in the maintenance of genomic stability and cell growth [5]. The products of these genes – BRCA1 and BRCA2 proteins – are involved in the repair of DNA double-strand breaks via the homologous recombination pathway. This mechanism is believed to be responsible for increased chemo-sensitivity, which results in better treatment outcomes [6, 7]. However, the impact of BRCA dysfunction on the prognosis of patients with epithelial ovarian cancer remains controversial and available analyses brought conflicting results [8, 9]. The better prognosis of patients with BRCA germline mutations is explained by cells inability to repair double-strand DNA breaks caused by platinum based chemotherapy [10].
BRCA germline mutations result in deficiency in repairing double-strand DNA breaks caused by platinum agents in every cell of the body. The aim of the study was to examine if patients with BRCA1-associated epithelial ovarian cancer have more treatment related adverse events and, if so, does it have impact on chemotherapy outcomes.
Material and methods
We conducted a retrospective analysis of an unselected population of patients treated in Maria Skłodowska-Curie Memorial Cancer Center and Institute of Oncology, Gliwice Branch between 2007 and 2013. Pathological stage of the disease was categorized according to International Federation of Gynaecology and Obstetrics (FIGO) 2009. The date of diagnosis was defined as the date of initial surgery. Response to chemotherapy was determined by computed tomography (CT) scan after completion of systemic treatment according to RECIST criteria 1.0. Recurrence/progression was diagnosed by CT, regardless of Ca-125 rise. Treatment related adverse events (AE’s) were: haematological toxicity, nausea/vomiting, neuropathy and mucositis. Grade of AE’s was determined using Common Terminology Criteria for Adverse Events (CTCAE). Platinum-resistant disease was defined by recurrence at ≤ 6 months after completion of chemotherapy.
Overall survival (OS) was calculated from the date of diagnosis to the date of patient’s death of any cause or last seen alive. Progression free survival (PFS) was calculated from the date of diagnosis the date of disease recurrence or patient’s death. We used exact Fisher test and χ2 test to compare BRCA1(+) and BRCA1(–) subgroups. The relationship between the occurrence of adverse events and treatment outcomes was analysed using the U Mann-Whitney and χ2 tests.
Results
One hundred and seventy-two 172 patients were treated for ovarian cancer at Maria Skłodowska-Curie Memorial Cancer Centre Gliwice Branch between 2007 and 2013. 96 of these patients have known BRCA mutation status (21 patients were BRCA1 positive and 75 – BRCA1 negative) and were included in our analysis. We did not note any BRCA2 mutation.
Median age in both subgroups was 52 years. Baseline performance status of patients was 0 (89 patients, 93%) or 1 (7 patients, 7%), with no severe comorbidities. Clinical and pathological characteristics of patients are detailed in Table 1.
Table 1 Clinical and pathological characteristics of patients
Parameter BRCA1(+) n = 21 BRCA1(–) n = 75 p
Median age [years] 52 (37–65) 52 (23–73)
FIGO stage
I 3 (14.3%) 16 (21.3%)
II 1 (4.8%) 9 (12%) 0.1
III 11 (52.4%) 44 (58.7%)
IV 6 (28.5%) 6 (8%)
Pathology
Serous 17 (80.9%) 44 (58.7%)
Mucinous 1 (4.8%) 7 (9.3%)
Endometrioid 2 (9.5%) 9 (12%) 0.53
Clear cell 0 5 (6.7%)
Others 1 (4.8%) 10 (13.3%)
Optimal debulking 9 (42.8%) 50 (65.3%) 0.08
Secondary cytoreduction 8 (66.7%) 25 (33.3%) 0.88
Median baseline Ca-125 level [IU/l] 265 32.65 0.04
Disease progression after 1st line chemotherapy 13 (61.9%) 41 (54.7%) 0.73
Platinum sensitivity
Sensitive 19 (90.5%) 64 (85.3%) 0.73
Resistant 2 (9.5%) 11 (14.6%)
Baseline Ca-125 level was significantly higher among BRCA1(+) woman (p = 0.04). We did not note significant differences in other analyzed parameters between BRCA1(+) and BRCA1(–) patients.
All patients received combined platinum-taxane chemotherapy (carboplatin AUC 5 and paclitaxel 175 mg/m2, every 21 days, intravenously). The number of cycles was 3–9, most patients received 6 cycles of chemotherapy (81 patients, 84%). We used ondansetron 8 mg (once or twice daily) and dexamethasone 8 mg in prevention of chemotherapy-induced nausea and vomiting. In case of insufficient antiemetic effect metoclopramide and/or thiethylperazine were applied. We did not use haematpoietic growth factors in any patient. For persistent neuropathy symptoms α lipoic acid 600 mg once daily was applied. In case of oral candidiasis we used locally nystatin or oral fluconazole 100 mg once daily.
We did not note differences in response to chemotherapy (complete remission, partial response, stable disease, progression) between BRCA1(+) and BRCA1(–) patients (OR = 1.71; 95% CI: 0.64–4.56; p = 0.28). Median PFS was 28.6 (8.4–69.2) months among BRCA1(+) patients and 22.2 (6.3–79.7) months in BRCA1(–) (p = 0.45). Median OS was 39.6 (16.3–79.8) months for BRCA1(+) patients and 38.2 (7.2–93.9) months for BRCA1(–) (p = 0.62).
The presence of BRCA1 mutation was not associated with more frequent occurrence of haematological toxicities of any grade (OR = 2.11; 95% CI: 0.79–5.64; p = 0.13), however, grade 3–4 haematological AE’s were significantly more common among BRCA1(+) patients (OR = 3.86; 95% CI: 1.14–13.23; p = 0.02). Neuropathy of any grade and neuropathy grade 3–4 were noted in comparable number of cases among both groups (OR = 1.19; 95% CI: 0.45–3.17; p = 0.73 and OR = 0.89; 95% CI: 0.09–8.39; p = 0.92, respectively). Nausea and vomiting of any grade occurred comparable in both groups (OR = 0.94; 95% CI: 0.34–2.62; p = 0.91). The number of nausea/vomiting grade 3–4 cases (2 in BRCA1(–) and 0 in BRCA1(+) patients) was too small to perform statistical analysis. The number of patients with mucositis was also too small to conduct credible analysis (1 case in BRCA(–) and 0 in BRCA1(+) patients, with no case of grade 3-4 mucositis). These results are summarized in Table 2.
Table 2 The relationship between chemotherapy related AE’s and BRCA1 mutation status
Parameter BRCA1(+) BRCA (–)
p
Haematological AE’s
Any grade
Grade 3–4
12 (57%)
6 (28.5%)
29 (38.7%)
7 (9.3%)
0.13
0.02
Neuropathy
Any grade
Grade 3–4
9 (42.9%)
1 (4.8%)
29 (38.7%)
4 (5.3%)
0.73
0.92
Nausea/vomiting
Any grade
Grade 3–4
7 (33.3%)
0
26 (34.7%)
2 (2.7%)
0.94
0.91
We did not notice more drugs dose reductions among hereditary ovarian cancer patients (OR = 3.29; 95% CI: 0.8–13.59; p = 0.09).
Among BRCA1(+) patients occurrence of any of above mentioned adverse events was not predictive for response to chemotherapy. In this subgroup haematological toxicities were not predictive for PFS (p = 0.75) and OS (p = 0.64), as well as neuropathy (p = 0.64 and p = 0.69 respectively) and nausea/vomiting (p = 0.97 and p = 0.73 respectively) (Table 3).
Table 3 The relationship between chemotherapy related AE’s and treatment outcomes in BRCA1(+) patients
Parameter Median PFS (months) p Median OS (months) p
Haematological AE’s
Yes
No
24.4
28.9
0.75
37.7
39.6
0.64
Neuropathy
Yes
No
23.7
28.9
0.64
39.6
37.7
0.69
Nausea/vomiting
Yes
No
29.3
26.5
0.97
39.6
37.7
0.73
Discussion
Evidence exists that ovarian cancer patients carrying germline BRCA mutations have an improved prognosis in comparison to sporadic cases [9–11]. BRCA-associated ovarian carcinomas are more aggressive but show higher susceptibility to platinum-salts and other DNA-damaging agents [10–15]. This phenomenon is explained by the fact that deficiency of BRCA1 or BRCA2 function leads to higher degree of chromosome instability and triggers alternative, less effective pathways to repair double-strand DNA breaks, resulting in accumulation of mutation events [15]. This mechanism is believed to be responsible for better response to platinum-based chemotherapy, but it may be also associated with higher toxicity of these agents [6, 7].
Data regarding differences in prognosis between BRCA1 and BRCA2 mutation related ovarian cancer are conflicting. Taken together, available studies confirm a significantly improved survival in BRCA2 mutation carriers in comparison to sporadic ovarian cancer patients, while this advantage for BRCA1 mutation carriers seems to be smaller [8, 10]. It might be explained by the fact that BRCA1 and BRCA2 work at different stage of DNA repair process. BRCA2 is believed to be the RAD51 protein regulator. This protein is required for homologous recombination pathway functioning. According to this hypothesis, BRCA2 is a mediator of the core mechanism of homologous recombination, while BRCA1 is more “universal” protein. We included only patients with BRCA1 mutation in our analysis, since we did not note any case of BRCA2 gene mutation. We observed significantly higher median baseline Ca-125 level (265 vs. 32.65 IU/l, p = 0.04) and numerically more FIGO stage IV cases (28.5% vs. 8%) among BRCA1(+) patients. Despite this, we did not note worse survival outcomes in this group in comparison to sporadic cases. These observations are in concordance with above mentioned literature data [8–12]. However, interpretation of our results should be careful due to small sample size.
Our study is retrospective and thus has some limitations. Besides small sample size, not all patients treated in the analysed time period were tested for BRCA mutation, so a selection bias might occur. Patients at younger age or/and with family history of breast or ovarian cancer cases are more likely to be referring to genetic testing. Not all patients were operated on at the same centre and we can therefore not be certain of uniform surgical quality. Moreover, reporting the occurrence of chemotherapy related AE’s might be biased due to retrospective nature of our study.
In summary, our data suggest that BRCA1(+) woman receiving platinum-based chemotherapy for epithelial ovarian cancer are more likely to experience grade 3–4 haematological adverse events (p = 0.02). This may result from higher sensitivity of their body cells to platinum agents. However, among BRCA1(+) patients occurrence of haematological AE’s or any other AE’s did not translate into better treatment outcomes. Our findings warrant further investigation in larger, prospective studies.
The authors declare no conflict of interest.
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References
1 Risch HA McLaughlin JR Cole DE Prevalence and penetrance of germline BRCA1 and BRCA2 mutations in a population series of 649 women with ovarian cancer Am J Hum Genet 2001 68 700 10 11179017
2 Frank TS Deffenbaugh AM Reid JE Clinical characteristics of individuals with germline mutations in BRCA1 and BRCA2: analysis of 10,000 individuals J Clin Oncol 2002 20 1480 90 11896095
3 Beristain E Martínez-Bouzas C Guerra I Differences in the frequency and distribution of BRCA1 and BRCA2 mutations in breast/ovarian cancer cases from the Basque country with respect to the Spanish population: implications for genetic counselling Breast Cancer Res Treat 2007 106 255 62 17262179
4 Boyd J Sonoda Y Federici MG Clinicopathologic features of BRCA-linked and sporadic ovarian cancer JAMA 2000 283 2260 5 10807385
5 Yoshida K Miki Y Role of BRCA1 and BRCA2 as regulators of DNA repair, transcription, and cell cycle in response to DNA damage Cancer Science 2004 95 866 71 15546503
6 Cass I Baldwin RL Varkey T Moslehi R Narod SA Karlan BY Improved survival in women with BRCAassociated ovarian carcinoma Cancer 2003 97 2187 95 12712470
7 Tan DS Rothermundt C Thomas K “BRCAness” syndrome in ovarian cancer: A casecontrol study describing the clinical features and outcome of patients with epithelial ovarian cancer associated with BRCA1 and BRCA2 mutations J Clin Oncol 2008 26 5530 6 18955455
8 Sun C Li N Ding D Weng D Meng L Chen G Ma D The role of BRCA status on the prognosis of patients with epithelial ovarian cancer: a systematic review of the literature with a meta-analysis PLoS One 2014 9 e95285 24788697
9 Bolton KL Chenevix-Trench G Goh C Association between BRCA1 and BRCA2 mutations and survival in women with invasive epithelial ovarian cancer JAMA 2012 307 382 90 22274685
10 Gallagher DJ Konner JA Bell-McGuinn KM Survival in epithelial ovarian cancer: a multivariate analysis incorporating BRCA mutation status and platinum sensitivity Ann Oncol 2011 22 1127 32 21084428
11 Chen P Huhtinen K Kaipio K Identification of prognostic groups in high-grade serous ovarian cancer treated with platinum-taxane chemotherapy Cancer Res 2015 75 2987 98 26122843
12 Safra T Borgato L Nicoletto MO BRCA mutation status and determinant of outcome in women with recurrent epithelial ovarian cancer treated with pegylated liposomal doxorubicin Mol Cancer Thera 2011 10 2000 7
13 Kaye SB Lubinski J Matulonis U Phase II, open-label, randomized, multicenter study comparing the efficacy and safety of olaparib, a poly (ADP-ribose) polymerase inhibitor, and pegylated liposomal doxorubicin in patients with BRCA1 or BRCA2 mutations and recurrent ovarian cancer J Clin Oncol 2012 30 372 9 22203755
14 Kwa M Edwards S Downey A Reich E Wallach R Curtin J Muggia F Ovarian cancer in BRCA mutation carriers: improved outcome after intraperitoneal (IP) cisplatin Ann Surg Oncol 2014 21 1468 73 24081797
15 Banerjee S Kaye S PARP inhibitors in BRCA genemutated ovarian cancer and beyond Curr Oncol Rep 2011 13 442 9 21913063
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Contemp Oncol (Pozn)Contemp Oncol (Pozn)WOContemporary Oncology1428-25261897-4309Termedia Publishing House 2890010.5114/wo.2016.64598Original PaperThe influence of Sm-153 therapy on bone marrow function Małkowski Bogdan 12*Maruszak Marta 1*Dudek Anna 3Wędrowski Mateusz 12Szefer Jarosław 11 Department of Nuclear Medicine, The Franciszek Lukaszczyk Oncology Centre, Bydgoszcz, Poland2 Department of PET and Molecular Imaging, Collegium Medicum in Bydgoszcz, Nicolaus Copernicus University in Toruń, Poland3 Department of Radiology, The Franciszek Lukaszczyk Oncology Centre, Bydgoszcz, Poland* Both first authors contributed equallyAddress for correspondence: Marta Maruszak, Department of Nuclear Medicine, The Franciszek Lukaszczyk Oncology Centre, Dr Izabeli Romanowskiej 2, 85-796 Bydgoszcz, Poland. e-mail: m.maruszak@gmail.com20 12 2016 2016 20 5 385 388 06 8 2015 09 3 2016 Copyright: © 2016 Termedia Sp. z o. o.2016This is an Open Access article distributed under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International (CC BY-NC-SA 4.0) License, allowing third parties to copy and redistribute the material in any medium or format and to remix, transform, and build upon the material, provided the original work is properly cited and states its license.Aim of the study
Studies about possible risks connected with β-emitterradiotherapy concentrate mainly on potential myelotoxicity. Results of previously published analysis based on white blood cells (WBC) and platelet (PLT) counts – before and after radionuclide treatment – are quite varied. The aim of our study was to present the greatest possible impact of Samarium-153 on bone marrow function in clinical practice.
Material and methods
The study included the blood test results of 175 patients with bone metastases treated with Sm-153 in the years 2012–2014. We compared levels of WBC, PLT, red blood cells (RBC), and haemoglobin (HGB) from two blood tests – one performed directly before the therapy and the other 2–6 weeks after isotope injection.
Results and conclusions
The study showed decreased mean level of WBC in a control test performed after therapy in comparison to output results at about 27.1%. In our study 1.1% of patients developed the third-grade toxicity in CTCAE (Common Terminology Criteria for Adverse Events). Mean decrease of PLT was about 18%. Three patients (1.7% of all) result qualified as third-grade toxicity in a control test, one as fourth-grade. Analysis of RBC level showed 5.7% reduction of output values. The same calculation was seen for HGB – 5.1%. The greatest but acceptable decrease in haematological parameters was observed in WBC and PLT. Analysis of changes in WBC and PLT level showed them to be similar or smaller than was proven in previously published studies.
bone metastasessamariumprostate cancerbreast cancerradionuclide therapyβ-emitters
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Introduction
Systemic radionuclide therapy using strontium and samarium has been well known and successfully used for nearly thirty years now.
Samarium-153 is a β- and γ-emitter with a physical half-life around 46.8 hours. It has proven affinity to bone tissue and reticuloendothelial system. Combination with EDTMP (ethylenediamine tetramethylene phosphonic acid), known as Quadramet, was developed in order to increase affinity to bones. Studies showed that concentration of Sm-153 is 17-times higher in osteoblastic metastases than in healthy bone tissue. 35% of injected Sm-153 dose is uptaken by the skeletal system. The remaining part is excreted by the kidneys within about 12 hours.
The analgesic effect of Sm-153 therapy is associated with a local reduction of radioinflammation and subsequent induction of apoptosis in cancer cells.
These pathways decrease the pressure exerted on pain receptors located in the periosteum. As a result, the pain subsides or fully resolves. The effect occurs 4–6 days after the isotope injection and can last for up to 16 weeks. Sm-153 therapy can be repeated dependent on the patient’s needs [1].
Sm-153 treatment is recommended for patients with multiple bone metastases with osteoblastic component, regardless of the primary tumour’s location.
The effectiveness of Sm-153 therapy is already proven [2]. According to studies, about 70% of patients observe a decrease of pain scores after one dose, and as much as 80% after the third drug administration.
Despite the high effectiveness and wide employment of Sm-153 in other countries, Poland struggles to fully accept this method. This attitude is based on a common opinion that the isotope injection must not be applied along with a radio- or chemotherapy. However, recent research conducted on patients suffering from prostate cancer proves otherwise. It has been shown that Sm-153 acts synergistically with the chemotherapy to reduce PSA levels and subsequently alleviate pain [3, 4].
Risk of myelosuppression has also been indicated as another reason against isotope therapy in Poland; however, this concern was based on experience with the Sr-89 isotope itself.
We decided to investigate the greatest possible impact of the Sm-153 on bone marrow function.
Material and methods
Our retrospective study included blood test results of 175 patients with multiple bone metastases, treated in our Department with Sm-153 in the years 2012–2014. The group consisted of 60 women, aged 33–86 years (mean 64.3 years) and 115 men, aged 53–87 years (mean 68.1 years). One hundred and four patients had prostate cancer, 44 – breast cancer, 7 – lung cancer, 6 – cervical cancer, 3 – endometrial cancer, 4 – kidney cancer, 1 – gallbladder cancer, 3 – colorectal cancer, 1 – urinary bladder cancer, 1 – leiomyosarcoma, and 1 – maxillary sinus cancer.
Patients were qualified for Sm-153 treatment based on up-to-bone scintigraphy and haematology results. Every whole body bone scan for therapy qualification was performed in our department 2–4 hours after injection of 800 MBq 99mTc-MDP. Scans were performed on a Symbia Truepoint SPECT/CT. Time of acquisition was 15–20 minutes.
Admitted patients received Quadramet intravenously at the dose of 37 MBq/kg. Injection took place in our Department. Every patient was obligatorily well hydrated with IV or per os before Sm-153 administration.
We compared levels of white blood cells (WBC), platelets (PLT), red blood cells (RBC), and haemoglobin (HGB) from two tests – one test had been performed directly before the therapy, whereas the second one was done 2–6 weeks after isotope injection in order to show changes in blood parameters.
Blood tests were performed in the Department of Laboratory Diagnostics in The Franciszek Lukaszczyk Oncology Centre, Bydgoszcz on Sysmex XT-1800i and Sysmex XT-2000i analysers using flow cytometry with semiconductor laser beam, sodium lauryl sulphate (SLS), and conductivity methods.
Reference ranges for blood tests results:
WBC 4–10 × 103/µl,
PLT 130–350 × 103/µl,
RBC 4–5 T/l for women and 4.5–5.5 T/l for men,
HGB 12–16 g/dl for women, 14–18 g/dl for men.
Results
The study showed a decreased mean level of WBC count in the test performed 2–6 weeks after therapy compared with output values at about 27.1% (Fig. 1, Table 1).
Fig. 1 Changes in WBC counts-decrease: increase in WBC level as a % of pretreatment result
Table 1 Changes from baseline in WBC, PLT, RBC, and HGB
WBC PLT RBC HGB
Mean decrease (%) 27.1 18 5.7 5.1
Nadir as % baseline 71.7 88.8 47.9 47.1
Sixty-three patients out of 175, representing 36% of the whole group, showed results under 4 × 103/µl.
The important finding was that most of the results (n = 45) in this group (63 patients) were still above 3 × 103/µl, despite the general patients’ decline. 1.1% of patients in our study developed third-grade toxicity in CTCAE [5]. There were no results qualified as fourth grade (Fig. 2).
Fig. 2 Post-treatment WBC counts in the group of patients with the results under the lowest normal level (63 patients from 175)
Analysis of PLT levels showed a decreased mean number of platelets, at about 18%. Only 39 patients (22.2%) had platelet counts under the lowest normal level (130 × 103/µl). Within the group of 175 patients, three patients (1.7%) noticed a result qualified as third-grade toxicity in CTCAE and one (0.57%) as fourth grade (Figs. 3, 4).
Fig. 3 Changes in PLT counts as a % of pretreatment results
Fig. 4 Post-treatment PLT counts in the group of patients with the results under the lowest normal level (39 patients from 175)
RBC and HGB results showed 5.7% mean reduction for RBCs (from 4.1 ±0.5 T/l to 3.8 ±0.5 T/l and 5.1% for HGBs (from 12.1 ±1.5 g/dl to 11.5 ±1.6 g/dl). Only three patients noticed HGB level qualified as third grade in CTCAE. There were no patients with fourth grade.
Discussion
The effectiveness of the Sm-153 therapy was not the aim of this study, although we would like to remind about data regarding pain reduction as a result of radionuclide treatment.
In the prospective, randomised, placebo-controlled study published by Serafini et al. [6] 118 patients received single doses of placebo (n = 39) or Sm-153 of dose 0.5 mCi/kg (n = 40) or 1.0 mCi/kg (n = 39). During 16 weeks of follow-up pain relief was observed already in the first four weeks in 62–72% of patients who received higher dose of Samarium. Marked or complete pain relief was observed in 31% of patients. It had a direct impact on the opioid use ratio (mean daily opioid use relative to baseline), which four weeks after drug administration ranged between 0.6–0.7 for 1.0 mCi/kg dose. At the end of observation – after 16 weeks – 43% of patients still notified pain relief.
Another study published by Correa-González et al. [7] analysed pain palliation of 277 patients who received 37 MBq Sm-153 per kg of body weight. Pain intensity was measured by Visual Analogue Scale and Verbal Rating Scale three times – once before treatment and also 3 and 12 weeks after drug administration. The comparison showed a marked decrease in pain intensity, by about 54% after three weeks and 74% after 12 weeks.
Despite the proven efficiency of Sm-153 therapy, its use is still restricted by anxiety about potential adverse effects of the therapy.
The aim of our study was to present the greatest possible impact of Sm-153 on bone marrow function. For this purpose, we analysed the differences between results from tests performed 2–6 weeks after the isotope injection. It has been proven previously that the decreased levels of blood parameters are only temporary and is followed by a quick recovery phase [2, 8, 9]. Because of that confirmed fact, our study did not include subsequent blood test results.
The results of the WBC count obtained in our study seem very close to those published by Heron et al. [10], in which haematology results of 58 patients receiving Sm-153 1–8 times were analysed. In that study, following the treatment, WBC count decreased by 30% from a mean of 5.6 ±0.2 × 103/µl to 3.7 ±0.2 × 103/µl (respectively, 27.1%, 6.7 ±2.2 × 103/µl and 4.7 ±1.7 × 103/µl in our study). 11% of patients have been noticed to develop the third-grade toxicity in CTCAE. By comparison, in our study only 1.1% of patients developed third-grade toxicity in CTCAE.
Regarding PLT count, the difference was more significant. Our study showed 18% reduction of PLT from the mean 240.1 ±96.8 × 103/µl to 191.9 ±88 × 103/µl (respectively, 40%, 259 ±9 × 103/µl and 157 ±8 × 103/µl in the study by Heron et al.) [10].
Six per cent of patients from the study by Heron et al. [10] had results ranging from 25 to < 50 × 103/µl (respectively, 0.57% in our study). In both studies there was one patient with PLT count under 25 × 103/µl (fourth-grade toxicity). In our study the lowest result was exactly 24 × 103/µl. As was previously stated in spite of PLT count decline, Sm-153 therapy is not associated with a significantly altered functional behaviour of platelets [11].
The WBC count results of our patients also showed smaller decreases compared to those published by Sartor et al. [2]. Following the Sm-153 therapy, 188 of patients in the study by Sartor et al. [2] had their WBC count decreased by 50% after the first dose of the isotope (in our study WBC count showed 27.1% decrease), whereas the PLT count was reduced by 44% (compared to 18% indicated in our study).
The final results of our study confirmed the small influence of Sm-153 on haematological parameters in patients treated with Sm-153. This may be a result of the high affinity of Sm-153 to osteoblastic metastases, and of the effect of low concentration of radionuclide in healthy bone tissue.
Taking in advance the low impact on the haematological parameters, radionuclide therapy should be considered in every case of a patient with multiple bone metastases with an osteoblastic component, regardless of the primary tumour’s location and present or planned type of therapy.
The authors declare no conflict of interest.
==== Refs
References
1 Turner JH Claringbold PG A phase II study of treatment of painful multifocal skeletal metastases with single and repeated dose samarium-153 ethylenediaminetetramethylene phosphonate Eur J Cancer 1991 27 1084 6 1720321
2 Sartor O Reid RH Bushnell DL Quick DP Ell PJ Safety and efficacy of repeat administration of samarium Sm-153 lexidronam to patients with metastatic bone pain Cancer 2007 109 637 43 17167764
3 Widmark A Modig H Johansson M TAXSAM: a new chemo-radiation regimen for bone metastases in hormone refractory prostate cancer Proceedings Prostate Cancer Symposium 2006 1 204
4 Fizazi K Beuzeboc P Lumbroso J A phase II trial of maintenance docetaxel and samarium in patients with castration-refractory bone metastases from prostate cancer with response or stabilization after induction docetaxel-estramustine: preliminary results Proceedings Prostate Cancer Symposium 2006 1 205
5 Common Terminology Criteria for Adverse Events v3.0 (CTCAE) August 9, 2006 Available at: http://ctep.cancer.gov/protocolDevelopment/electronic_applications/docs/ctcaev3.pdf .
6 Serafini AN Houston SJ Resche I Palliation of pain associated with metastatic bone cancer using samarium-153 lexidronam: a double-blind placebo-controlled clinical trial J Clin Oncol 1998 16 1574 81 9552068
7 Correa-González L Arteaga de Murphy C Pichardo-Romero P Pedraza-López M Moreno-García C Correa-Hernández L 153Sm -EDTMP for pain relief of bone metastases from prostate and breast cancer and other malignancies Arch Med Res 2014 45 301 8 24681187
8 Collins C Eary JF Donaldson G Samarium-153-EDTMP in bone metastases of hormone refractory prostate carcinoma: a phase I/II trial J Nucl Med 1993 34 1839 44 8229221
9 Resche I Chatal JF Pecking A A dose-controlled study of 153Sm-ethylenediaminetetramethylenephosphonate (EDTMP) in the treatment of patients with painful bone metastases Eur J Cancer 1997 33 1583 91 9389919
10 Heron DE Brufsky A Beriwal S Kurman M Myelotoxicity of samarium Sm 153 lexidronam in patients receiving prior treatment with chemotherapy or radiotherapy Ann Oncol 2008 19 1639 43 18467311
11 Weiss K Palumbo B Palumbo I Palumbo R Granegger S Hiltunen J Sinzinger H Platelet function after single [153Sm] EDTMP therapy in prostate cancer Q J Nucl Med Mol Imaging 2006 50 330 3 17043630
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Contemp Oncol (Pozn)Contemp Oncol (Pozn)WOContemporary Oncology1428-25261897-4309Termedia Publishing House 2890210.5114/wo.2016.64600Original PaperEvaluation of efficacy of Caphosol in prevention and alleviation of acute side effects in patients treated with radiotherapy for head and neck cancers Kiprian Dorota Jarzabski Andrzej Kawecki Andrzej Comprehencive Cancer Center, Warsaw, PolandAddress for correspondence: Dorota Kiprian, Comprehencive Cancer Center, Warsaw, Poland. Roentgena 5, 02-781 Warsaw, Poland. e-mail: dkiprian@wp.pl20 12 2016 2016 20 5 389 393 15 4 2014 14 1 2016 Copyright: © 2016 Termedia Sp. z o. o.2016This is an Open Access article distributed under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International (CC BY-NC-SA 4.0) License, allowing third parties to copy and redistribute the material in any medium or format and to remix, transform, and build upon the material, provided the original work is properly cited and states its license.Aim of the study
Oral mucositis is a common side effect of the oral mucosa due to anticancer therapy, especially for head and neck cancer. Caphosol is indicated for dryness of the mouth and oropharynx and treatment of mucositis due to irradiation or high-dose chemotherapy. The aim of the study was to evaluate the efficacy of Caphosol in preventing and alleviating mucositis due to radiotherapy in the head and neck region.
Material and methods
Caphosol was used from the beginning of the irradiation and for two weeks more after the treatment was completed. Mucositis, xerostomia, and dysphagia were scored by radiotherapists. Subjective evaluation was made by patients. Caphosol was assessed in a non-blinded, matched clinical study. Each treatment arm consisted of 50 patients. The groups were similar. The only difference in the management protocol between the treatment arms was the use of Caphosol in the experimental arm.
Results
A statistically significant difference in mean severity of early irradiation-induced side effects between the studied groups was observed with respect to: mucositis in the clinical target volume (CTV) area, mucositis in the increased dose (boost) area, dysphagia and xerostomia (p < 0.001 for all reactions). In the group of patients who used Caphosol, the mucositis was less intense, both in the CTV and in the boost area.
Conclusions
The use of Caphosol reduces the severity of acute mucositis, dysphagia and xerostomia, exerting a positive effect on comfort in the oral cavity in patients irradiated for head and neck tumors.
head and neckradiotherapymucositisCaphosol
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Introduction
Oral mucositis is a common side effect of the oral mucosa due to anticancer therapy, especially for head and neck cancer [1]. Chemotherapy is administered systemically, whereas radiation therapy affects a mucosal membrane locally. Post-irradiation mucositis typically manifests as erythema, swelling, atrophy and ulceration [2, 3]. Chemotherapy-induced mucositis usually develops within 4–7 days after initiation of treatment and lasts about 2 weeks. Radiation-induced mucositis typically begins at cumulative doses of about 10–15 Gy (about 10 days of treatment) and typically lasts for weeks after the treatment is completed. Severity of mucositis depends on many factors, related to therapy and patient characteristics such as the method of fractionation, the total dose, the treatment strategy, oral hygiene during the therapy, as well as individual genetic predispositions. The majority of patients treated for head and neck cancers or those receiving high-dose chemotherapy develop severe oral mucositis. Patients often complain of taste changes, difficulty in talking and swallowing, pain and oral dryness. Severe oral mucositis can lead to bacterial and fungal infection, difficulty with swallowing and decreased patient’s quality of life. Significant progress has been made in understanding the pathobiology of mucositis in the last decade. The biological model of mucositis due to anticancer therapy proposed by Sonis in 2004 presents that mechanism as a cascade of pro-inflammatory cytokines TNF-α, IL-1, and IL-6 activated by free radicals. This pathobiological cascade is described in five phases: initiation, up-regulation with generation of messengers, signaling and amplification, ulceration with inflammation, and, finally healing [2]. The understanding of this molecular mechanism of radiation-induced mucositis has opened new possibilities for investigators to develop a proper strategy in prevention and treatment of mucositis. Management of oral mucositis has been the subject of many publication each year [4–6]. There are several products available for the prevention and treatment oral mucositis [7–9], but there are no gold standard strategies to prevent and treat oral mucositis. Based on a comprehensive systematic review of the literature, the Mucositis Study Group of the Multinational Association for Supportive Care in Cancer and the International Society of Oral Oncology (MASCC/ISOO) has developed clinical practice guidelines for the management of mucositis. The last guidelines were published in January and February 2013 in Supportive Care in Cancer [10–13]. That is why many new products and medicines are being investigated to tackle the problem of oral mucositis. Caphosol is a supersaturated solution of calcium phosphate. It is designed to moisten, lubricate and cleanse the mucosa, and replace key minerals (calcium and phosphate) which are involved in repairing and maintaining mucosal integrity. Calcium ions have an antiinflammatory function, lower the prostaglandin production and promote tissue regeneration. Phosphate ions can protect against infections and maintain an appropriate pH level. High concentrations of calcium and phosphate allow the ions to diffuse into intercellular epithelial spaces and permeate mucosal lesions.
Aim of the study
The aim of the study was to assess the efficacy of Caphosol in prevention and alleviation of acute side effects of irradiation in patients irradiated for head and neck cancer.
Material and methods
This study was performed in accordance with the global standards of the International Conference on Harmonization – Good Clinical Practices (ICH-GCP), the Council for International Organizations of Medical Sciences International Ethical Guidelines for Biomedical Research Involving Human Subjects (CIOMS, 2002), applicable local regulatory requirements and the ethical principles that have their origin in the Declaration of Helsinki. The study complies with all laws and regulations in Poland and has been carried out in a manner respectful of the local culture and consistent with legal statutes and regulations for the protection of human subjects. Patients with head and neck cancer referred for radiotherapy or radiochemotherapy with radical intent were included in this study. Caphosol was assessed in a non-blinded, matched clinical study. Caphosol was used as a mouthwash from the first day of irradiation throughout the whole course of the therapy and two weeks after the treatment was completed. Initially, the patients used it for the oral cavity and the throat 4 times a day. The frequency of application was increased up to 10 times a day depending on the severity of symptoms associated with mucositis. The severity of acute side effects such as mucositis, dysphagia and xerostomia was assessed by a radiation oncologist according to the European Organization for Research and Treatment of Cancer/Radiation Therapy Oncology Group (EORTC/RTOG) scale once a week during the therapy and one month after its completion. Other criteria taken into consideration were: dietary supplements, the use of non-steroid anti-inflammatory drugs (NSAIDs), opioids, mucolytic agents, and prolonged hospitalization. The subjective assessment of patient satisfaction was made by completing a questionnaire.
Material and statistical analysis
The total number of patients included in this study was 100. The patients were matched into two arms equal in diagnosis and treatment strategy (Tables 1 and 2). In the experimental arm patients received Caphosol and in the control arm standard treatment, which was recommended in the Head and Neck Cancer Department.
Table 1 Clinical material
Therapy Method Number of patients
3 D IMRT SIB-IMRT
Radiotherapy alone 1 14 5
Concomitant radiochemiotherapy 1 11 18
Table 2 Clinical material
Diagnosis Number of patients (F – 15; M – 35)
Nasopharyngeal cancer 13
Oropharyngeal cancer 18
Laryngeal and hypophlaryngeal cancer 5
Post-operative floor of the mouth cancer 8
Tongue cancer 4
Sarcoma of the mandibule post-operative 1
FPI 1
Severity of the selected acute side effects (measured according to the RTOG/EORTC scale) according to a developed algorithm was adopted as a criterion of assessment. The mean value based on all measurements was analyzed as a continuous variable. Other criteria such as dietary supplements, use of non-steroid anti-inflammatory drugs (NSAIDs) and opioids as well as the fact of prolonged hospitalization were analyzed as a percentage of answers. Standard descriptive statistics tools – frequency tables and contingency tables for bivariate data, as well as maximum and minimum values, mean value and standard deviation for continuous variables with normal distribution, or quartiles in the case of different distribution – were used for description of the material. Student’s t-test or the nonparametric Mann-Whitney test was used to test the significance of differences for continuous variables, depending on their distribution. Percentage values were compared using the χ2 independence test. All comparisons were made at the statistical significance level α = 0.05. The estimated values were presented with the 95% confidence interval (CI).
Results
A statistically significant difference in mean severity of acute side effects between two matched groups was observed in: mucositis level in the CTV area, mucositis level in the escalated dose (boost) area, dysphagia and xerostomia (p < 0.001 for all reactions). In the group of patients receiving Caphosol the mucositis was less intense, both in the CTV and in the boost area. The fact of reduced severity of dysphagia in patients receiving Caphosol is an interesting observation. The difference is much greater than the effect of the reduction of mucositis level in the boost area. Thus, it can be concluded that despite severe mucositis the patients who used Caphosol were able to swallow. The mean values for the reactions and the mean differences with 95% CI are presented in Table 3 and illustrated in Figs. 1–4. Lower use of opioid analgesia in radiotherapy patients receiving Caphosol compared to those receiving standard treatment for oral mucositis was noted (p < 0.001) (Fig. 5). There was also a difference in the frequency of prolonged hospitalizations between these two groups of patients. In the experimental group patients did not have reduced prolonged hospitalization due to severe post-treatment mucositis (p < 0.001) (Fig. 6). There were no statistically significant differences in the use of dietary supplements, NSAIDs and mucolytic agents between the two groups. The results of subjective patient satisfaction with reduction of dryness and improvement of comfort in the oral cavity after Caphosol are presented in Fig. 7. The median for both assessments was higher than 50% (slight improvement) with statistical significance (p < 0.001) and was, together with 25% and 75% quartiles for dryness reduction and comfort improvement, 75% (58%, 92%) and 83% (75%, 100%), respectively, whereas the respective minimum and maximum borderline values were 40% and 100%, and 33% and 100%.
Table 3 Comparison of the severity of early reactions to irradiation in the analyzed groups.
Parameter Caphosol N Mean reaction value Standard deviation Mean difference Left borderline 95% CI Right borderline 95% CI P T-Test
CTV mucositis 0
1 50
50 1.2906
0.7993 0.41222
0.35302 0.49137 0.33279 0.64994 < 0.001
Boost mucositis 0
1 50
50 1.7681
1.2215 0.53435
0.45388 0.54657 0.34170 0.75145 < 0.001
Dysphagia 0
1 50
50 1.4590
0.8230 0.57327
0.50210 0.63606 0.41348 0.85865 < 0.001
Xerostomia 0
1 50
50 1.1142
0.8493 0.31264
0.36668 0.26498 0.12490 0.40505 < 0.001
Fig. 1 Comparison of the severity of early mucositis reaction in the CTV area in the analysed groups
Fig. 2 Comparison of the severity of early mucositis reaction in the boost area in the analysed groups
Fig. 3 Comparison of the severity of dysphagia in the analysed groups
Fig. 4 Comparison of the severity of xerostomia in the analysed groups
Fig. 5 Comparison of the opiods use in the analysed groups
Fig. 6 Mean prolongation of hospitalization time (days) in the analysed groups
Fig. 7 Assessment of xerostomia and increase of oral cavity comfort improvement in the analysed groups
Discussion
All patients treated with radiation therapy alone or in combination with chemotherapy for the head and neck region develop mucositis in the oral cavity, which has a negative influence on overall treatment time and quality of life. The patients often require administration of narcotic analgesics, parenteral nutrition, and antibiotics. Severe mucositis may lead to prolonged or additional hospital stay and therapy interruptions [14].
There are several products available for the treatment of oral mucositis. Some of them prevent oral mucositis by their anti-inflammatory potential and protect the oral mucosa. Others help maintain oral hygiene, and moisten and lubricate the oral cavity. The efficacy of all of these products is not well established, and there is still no “gold standard” for oral mucositis prevention and treatment. Apart from the clinical efficacy, it is important to consider the potential reduction in healthcare costs (length of hospitalization, analgesia, and specialist care) that could be achieved by preventing or reducing the incidence and/or duration of severe oral mucositis, when cost-effectiveness has become a necessary aspect of health commissioning. Many publications and numerous single-centre observations of Caphosol efficacy have been published during the past few years. Recent British guidelines on prevention and treatment of oral mucositis prepared by a UK multidisciplinary expert group of cancer and palliative care specialists suggest the use of a Caphosol rinse 4–10 times a day from the first day of treatment [15]. Most studies concerning the use of Caphosol in prevention and treatment of oral mucositis had a single-center design and compared patients receiving Caphosol with a matched group or historic controls receiving standard therapy [16–18]. The majority of these studies reported a lower incidence and severity of oral mucositis in patients receiving high-dose chemotherapy due to hematology malignancies and radiotherapy [19]. Only a few studies investigating the efficacy of Caphosol in patients treated with radio- or radiochemotherapy for head and neck cancer have been published to date. In two studies no preventive effect of Caphosol in severity of mucositis in this group of patients was found [20, 21], but despite this observation 50% of patients reported reduction of oral mucositis related symptoms, which was correlated with pain, swallowing and eating. In the present study reduction of severity of irradiation-induced mucositis was observed in the experimental group of patients in the CTV (clinical target volume) area and in the boost volume (the volume receiving a higher dose per fraction) area in comparison to the control group, and the difference was significant (p < 0.001). In the boost volume the severity of mucositis was increased, but it was lower as compared to the control matched group. The fact of reducing severity of dysphagia in patients receiving Caphosol is a very interesting observation. The difference is higher than the effect of Caphosol in reduction of mucositis in the boost area. Thus, it can be concluded that despite severe mucositis the patients receiving Caphosol were able to swallow and could eat. This observation is very similar to the data mentioned above. The reduction of opioid use observed in the present study agrees well with data from other publications. Data from the few studies suggest that Caphosol is well tolerated. Patients using Caphosol from the first day of treatment reported higher satisfaction, lower incidence of subjective feeling of dry mouth, and improvement of comfort in the oral cavity. These data are very similar to observations from many different studies. The effect of Caphosol on duration of hospitalization also seems to be important [22]. It was found that none of the Caphosol-treated patients had oral mucositis-related hospitalization, compared with 19% in the control group. In the present study shorter time of hospitalization due to post-treatment mucositis was observed. This observation correlates with data published by Godfrey and Cuccurullo from 2010 [23]. The effect of Caphosol on duration of hospitalization and opioid use may reduce the overall costs of treatment. The positive effect of Caphosol on comfort in the oral cavity and reduction of mucous dryness, evident on the basis of the patients’ assessments, is also very important. Improved comfort in the oral cavity and reduced dryness of the oral mucous may have a positive influence on the patient’s quality of life.
Despite the small size of the analyzed patient population, the differences are statistically significant. Hence we can conclude that Caphosol plays an important role in prevention and alleviation of irradiation-induced mucositis.
The authors declare no conflict of interest.
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References
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14 Rodrıguez-Caballero A Torres-Lagares D Cancer treatment-induced oral mucositis: a critical review Int J Oral Maxillofac Surg 2012 41 225 38 22071451
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17 Dłuzniewska A Gozdzik J Zygadlo D Skoczen S Krasowska-Kwiecień A Czogala W Wiecha O Supersaturated calcium phosphate rinse (Caphosol) in the management of mucositis after haematopoietic stem cell transplantation – single-centre experience 37th Annual Meeting of the European Group for Blood and Marrow Transplantation 2011
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19 Haas M Mercedes T Manyak M Treatment of Oral Mucositis by Supersaturated Calcium Phosphate Oral Rinse in Patients Receiving Chemo-therapy (CT) and Radiation (RT) American Society for Radiation Oncology 50th Conference. Conference Proceedings 2008 Abstract 2530
20 Rao N Trotti A Kim J Phase II multicenter trial of Caphosol for the reduction of mucositis in patients receiving radiation therapy for head and neck cancer Int J Radiat Oncol Biol Phys 2011 81 Suppl. 2 S75
21 Stokman M Burlage F Spijkervet F The effect of a calcium phosphate mouth rinse on chemo/radiation induced oral mucositis in head and neck cancer patients. A prospective study Support Care Cancer 2010 18 Suppl S114 Abstract 08-075
22 Miyamoto C Wobb J Micaily B Li S Achary M A retrospective match controlled study of supersaturated calcium phosphate oral rinse (SCPOR) vs supportive care for radiation induced oral mucositis 2009 International MASCC/ISOO symposium
23 Godfrey L Cuccurullo C Analysis of mucositis-associated health outcomes in patients treated with image-guided IMRT for head and neck cancer: should Caphosol be included in the MASCC/ ISOO mucositis guidelines? Support Care Cancer 2010 18 Suppl S108–S109 Abstract 08-064
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Contemp Oncol (Pozn)Contemp Oncol (Pozn)WOContemporary Oncology1428-25261897-4309Termedia Publishing House 2890410.5114/wo.2016.64602Original PaperAntineoplastic chemotherapy and congenital tooth abnormalities in children and adolescents Krasuska-Sławińska Ewa 1Brożyna Agnieszka 2Dembowska-Bagińska Bożenna 2Olczak-Kowalczyk Dorota 31 Department of Paediatric Dental Surgery, Children’s Memorial Hospital, Warsaw, Poland2 Department of Paediatric Oncology, Children Memorial Hospital, Warsaw, Poland3 Department of Paediatric Dentistry, Warsaw Medical University, PolandAddress for correspondence: Ewa Krasuska-Sławińska, The Childrens’ Memorial Heath Institute, Al. Dzieci Polskich 20, 04-730 Warsaw, Poland. e-mail: e.krasuska@czd.pl20 12 2016 2016 20 5 394 401 23 3 2015 30 11 2015 Copyright: © 2016 Termedia Sp. z o. o.2016This is an Open Access article distributed under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International (CC BY-NC-SA 4.0) License, allowing third parties to copy and redistribute the material in any medium or format and to remix, transform, and build upon the material, provided the original work is properly cited and states its license.Aim of the study
Chemotherapeutic treatment in children and adolescents carries a risk of congenital tooth disorders and dentinoma. Study objective is to assess the correlation between tooth abnormalities, early complications of multidrug chemotherapy, and chemotherapeutics used in different antineoplastic therapies in children and adolescents.
Material and methods
Enamel defects (developmental defects of enamel index – DDE index) and defects in tooth number, size, and structure were assessed clinically and radiologically in 60 patients who underwent chemotherapy on average 4.9 ±3.4 years earlier (PCH), and 60 generally healthy subjects (control group – CG), aged 6–18 years. Höltta’s defect index (DeI) was calculated. Medical files provided information on neoplasm type, age at treatment start and chemotherapy duration, chemotherapeutic type and dose, vomiting, and mucositis (CTCAE v4.0). Statistical significance of differences between groups was assessed with the Mann-Whitney U test and the correlation between dental defects and chemotherapy with Spearman’s rank correlation coefficient (significance p ≤ 0.05).
Results
Enamel defects, tooth agenesis, microdontia, root resorption, taurodontism, and dentinoma occurred statistically significantly more often in the PCH group. A correlation was established between vincristine use and dose and all types of dental defects; cyclophosphamide, doxorubicin, and isophosphamide and hypodontia; microdontia, root resorption, and enamel defects; etoposide and cisplatin and microdontia, root resorption, and enamel defects; methotrexate root resorption and enamel defects; carboplatin and dentinoma and enamel defects. Mucositis and vomiting promoted root resorption, microdontia, and enamel defects.
Conclusions
Dental defects are related to both the use of respective chemotherapeutics, especially vincristine, cyclophosphamide, doxorubicin, and isophosphamide, and to early complications in multidrug chemotherapy – mucositis and vomiting. Vincristine and carboplatin use may promote dentinoma.
neoplasmchemotherapychildrenenamel defectsagenesismicrodontiacongenital root abnormalities
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Introduction
Multidrug chemotherapy allows effective treatment of more than 70% of children with neoplasms, independently of the disease type or stage [1–9]. Unfortunately, chemotherapeutics are not selective and have a low therapeutic index, which results in damaging also healthy cells. To increase therapy effectiveness and, at the same time, minimise its side effects, several chemotherapeutic agents, with different mechanisms of action, at minimal therapeutic doses tolerated by the host, are used in multidrug chemotherapy. Unfortunately, even despite that, chemotherapy presents risks of side effects, i.e. early and late complications.
Children under antineoplastic treatment in early childhood present more often tooth aplasia, microdontia, root resorption, and congenital enamel defects than generally healthy children. Taurodontism, enlarged pulp chamber, and supernumerary teeth also occurred more often [10–43].
Congenital defects, which often occur in neoplasms or are early chemotherapy complications, may result from fever, metabolic disorders and hormonal imbalance, and malnutrition. Chemotherapeutics may also have a direct impact on dental tissues; e.g. vincristine, colchicine, and vinblastine temporarily impair odontoblast activity [7, 43–45]. Chemotherapy probably also delays the development of the Hertwig sheath [23].
Multidrug chemotherapy makes it more difficult to assess the impact of respective drugs on odontogenesis and tooth pulp. Up to now, most researchers have assessed the impact of chemotherapy on teeth in children with leukaemia. There is little information on the effects of chemotherapeutics in other neoplasm therapies, although brain and germ cell tumours are common under the age of five years.
The present study aims to assess the correlation between the prevalence of congenital defects in permanent teeth and early complications of multidrug chemotherapy and chemotherapeutics used in various neoplasms in children.
Material and methods
Patients
The study was approved by the Children’s Memorial Hospital Commission for bioethics on May 12, 2010 (permit 95/KBE/2010), and patients/their legal guardians consented to participate in the research study.
One hundred and twenty patients under the age of 18 years, including 60 who completed chemotherapeutic treatment for neoplasms at least one year earlier (PCH group; mean age 11.81 ±3.87 years) at the Oncology Clinic of the Children’s Memorial Hospital, and 60 generally healthy patients (CG – control group; mean age 12.22 ±3.63 years), treated at the Paediatric Dental Clinic of the Children’s Memorial Hospital, were examined. Children with chronic diseases other than neoplasms, or undergoing or having undergone chronic treatments, or after radiation therapy in the head and neck region, were excluded from the research study. Patients from both groups were of similar socioeconomic status.
Methods
Retrospective analysis of medical files
Patient medical files were analysed for information on neoplasm type, age at treatment start, antineoplastic treatment duration, chemotherapeutic type and dose, and early chemotherapy complication prevalence and severity, i.e. vomiting and mucositis according to CTCAE v4.0 [46]. Accumulated doses that every patient received under treatment were calculated. All doses were then converted into mg/m2.
Dentition
All tooth surfaces were clinically assessed in successive quadrants. Tooth number, congenital disorders, including anatomic crown size and shape, and enamel defects were assessed with the modified DDE index (opacities, hypoplasia, and combination of both) [47].
Pantomographs served to assess congenital disorder prevalence: no tooth buds (agenesis was diagnosed when there was no tooth/tooth bud after extraction was ruled out), hypodontia, microdontia (when tooth width was smaller or equal to half of the normal size), anatomic crown disorders, i.e. resorption, V-shape, U-shape, taurodontism (in the case of excessive vertical elongation of the tooth chamber with no tooth neck, and a lowered root bifurcation in multiradicular teeth) [23, 47–49]. Höltta’s defect index (DeI) was used [23].
No bud of the first premolar in children aged less than five years or of the second premolar and second molar in children under six years old, as well as poor visibility of teeth on the pantomograph, led to exclusion from the assessment. Furthermore, teeth with unfinished root development or with important root curves, teeth with attrition, abrasion or anatomic crown fracture, and third molars were also excluded from root assessment.
The assessed teeth were attributed the following codes:
D0 – no congenital disorders; ratio R/C > 1.6,
D1 – ratio R/C from 1.6 to 1.2 – mild root resorption,
D2 – ratio R/C from 1.1 to 0.9 – severe root resorption,
D3 – ratio R/C < 0.9 – severe root resorption,
D4 – microdontia,
D5 – no tooth (aplasia).
Root length assessment included the longest root in multiradicular teeth, and the longest buccal root in mandibular molars and premolars. Crown height was calculated with measurement points at the line crossing through the incisive side of front teeth and buccal cusps of premolars and molars. R/C, i.e. the ratio of root length (R) to crown length (C), was calculated.
The prevalence of congenital disorders in respective teeth was assessed, and DeI was calculated with the formula (nD1 × 1) + (nD2 × 2) + (nD3 × 3) + (nD4 × 4) + (nD5 × 5), where n was the number of teeth with respective D1, D2, D3, D4, and D5 codes.
Statistical analysis
Results were statistically analysed with the nonparametric Mann-Whitney U test (after a preliminary analysis of the compatibility of numeric values distribution with real distribution with the Shapiro-Wilk test). The impact of chemotherapy-related factors on dentition was assessed with Spearman’s rho. Statistical significance was set at p ≤ 0.05.
Results
The mean age at chemotherapy start was 5.9 ±4.0 years, and treatment duration was 1.3 ±0.5 years. On average, 4.9 ±3.4 years elapsed since chemotherapy completion. Chemotherapy was used to treat: Burkitt’s lymphoma (15.0%), nephroblastoma (13.0%), neuroblastoma (10.0%), histiocytosis (8.3%), rhabdomyosarcoma (6.7%), Ewing’s sarcoma (6.7%), medulloblastoma (5.0%), neurofibromatosis type I (5.0%), and others (19.7%). The treatment protocols were appropriate for the respective diagnosis. The drugs most often used in combination therapy included: vincristine (VCR), cyclophosphamide (CTX), doxorubicin (ADM), etoposide (VP-16), cisplatin (CDDP), ifosfamide (IF), and actinomycin (ACTD). Other drugs were used in < 15% of patients. Table 1 presents the antineoplastic treatments.
Table 1 PCH patient characteristics
Chemotherapeutic agent n Mean dose ± SD (mg/m2)
Vincristine (VCR) 53/88.0 10.46 ±8.0
Cyclophosphamide (CTX) 41/68.3 5287.18 ±12233.51
Doxurubicin (ADM) 40/66.5 167.41 ±152.43
Etoposide (VP-16) 39/65.0 1434.58 ±1712.87
Cisplatin (CDDP) 26/43.03 255.92 ±402.08
Ifosfamide (IF) 25/41.6 12511.67 ±21032.63
Actinomycin (ACTD) 18/30.0 3.06 ±8.54
Dacarbazine (DTIC) 17/28.3 1649.14 ±2757.64
Methotrexate (MTX) 13/21.6 3795.90 ±8195.43
Carboplatin (CBDCA) 11/18.3 1478.70 ±7148.41
Vinblastine (VBL) 8/13.3 15.33 ±56.24
Cytarabine (Ara-C) 8/13.3 1592.86 ±5498.39
Teniposide (VM-26) 7/11.6 155.67 ±446.76
5-Fluorouracil (5-FU) 3/5.0 83.33 ±457.95
Bleomycin (BLM) 2/3.3 3.00 ±17.06
Irinotecan (IRI) 2/3.3 38.33 ±247.72
Dentition
Enamel defects were observed statistically significantly more often in PCH than in controls (Table 2). PCH also presented higher mean numbers of teeth with opacities (6.316 ±6.10 vs. 1.866 ±2.64; p = 0.000) and hypoplasia (1.516 ±3.61 vs. 0.15 ±0.55; p = 0.003). There was no significant difference (0.533 ±1.83 vs. 0.083 ±0.38 respectively; p = 0.06) between mean numbers of teeth with a combination of enamel defects. Spearman’s rho analysis revealed a positive correlation between enamel defect prevalence and age at chemotherapy start and its duration. Vomiting and the use and doses of vincristine, carboplatin, cyclophosphamide, doxorubicin, ifosfamide etoposide, and cisplatin were linked to the prevalence of opacities. Vincristine, methotrexate and mucositis showed a positive correlation with hypoplasia (Table 3).
Table 2 Congenital disorders and DeI in patients after anti-neoplastic treatment and in the control group
Congenital disorders PCH CG p
n/%
Enamel defects 53/88.3 24/40.0 0.000*
opacities (DDE index: 1, 2, 5) 34/56.6 19/32.3 0.006*
hypoplasia (DDE index: 3) 7/11.6 1/1.6 0.001*
combination of lesions (DDE index: 6, 7) 12/20 4/6.6 0.068
Root resorption (D1 + D2 + D3) 36/60.0 25/41.6 0.0450*
V-shaped 18/30.00 0/0.0 0.0000*
Microdontia (D4) 12/21.67 0/0.0 0.0003*
no tooth bud (D5) 16/26.67 4/6.66 0.0035*
DeI > 0 45/75.00 2643.33/ 0.0004*
DeI mean ± SD
12.48 ±13.16 2.24 ±3.84 0.0000*
DeI component D1 + D2 + D3 5.65 ±6.92 1.81 ±3.03 0.0009*
Others n/%
taurodontism 12/20.00 3/5.00 0.0135*
mesiodens 1/1.67 0/0.0 0.3254
Dentinoma 18/30.0 9/15.0 0.0505
Impacted teeth 6/10.00 2/3.33 0.1466
* statistically significant differences; p ≤ 0.05
Table 3 Statistically significant Spearmen’s rho for enamel defects and factors related to used anti-neoplastic treatment
Opacities Hypoplasia Combination of defects
Age at chemotherapy start 0.2955* 0.1845* 0.1568*
Treatment duration 0.1943* 0.1980* 0.1459
VCR 0.2536* 0.1513* 0.0689
Dose 0.2401* 0.1186 0.0837
CBDCA 0.1504* 0.0164 0.0148
Dose 0.1493* –0.0089 –0.0057
CTX 0.1834* 0.1136 0.0459
Dose 0.2034* 0.1198 0.0761
ADM 0.1937* 0.1219 0.0287
Dose 0.2042* 0.0834 0.0239
IF 0.1874* 0.0355 –0.0249
Dose 0.1720* 0.0339 –0.0201
MTX 0.0557 0.1546* 0.0535
Dose 0.0543 0.1568* 0.0524
VP-16 0.3239* 0.0696 0.0208
Dose 0.2907* 0.0724 0.0058
CDDP 0.2436* 0.0915 0.0772
Dose 0.2536* 0.0612 0.0517
Mucositis 0.1785* 0.1246 0.1395
Grade 2 0.1391 0.2099* 0.2023*
Vomiting 0.2550* 0.0246 0.0271
Dental defects visible on pantomographs occurred statistically significantly more often in PCH than in controls (53.3% vs. 76.7%; p = 0.0077). More than one congenital defect (p = 0.0000) occurred in 46.7% of patients after chemotherapy, and only in 10% of controls (p = 0.0000). Root resorption was the most common defect (Table 2). The prevalence of short roots and the mean DeI component related to this defect (D1 + D2 + D3) were statistically significantly higher in PCH than in CG. Severe and very severe root absorption (38.33% vs. 6.66%; p = 0.0000) occurred significantly more often in this group. In PCH the resorption occurred more often in first molar roots (in 21.6% of patients), and less often in incisors (15%), premolars (15%), and second molars (10%). In controls it most often (5.0% of subjects) occurred in first molars. Generally healthy patients did not present any important premolar root resorption or V-shaped roots. The analysis of Spearman’s rho revealed a positive correlation between dental root resorption and age at treatment start, and the use of vincristine, cyclophosphamide, ifosfamide, cisplatin P, and their doses. Early chemotherapy complications had no impact on this congenital defect (Table 3). A similar analysis of severe and extremely severe root resorption revealed a positive correlation also with doxorubicin, etoposide, teniposide, and vomiting (Table 3). The D1 + D2 + D3 component of DeI was correlated with vincristine, cyclophosphamide, doxorubicin, ifosfamide, etoposide, and cisplatin use, age at treatment start, sometimes treatment duration, and grade 3 mucositis (Table 3).
Tooth agenesis occurred also more often in patients after chemotherapy than in controls (Table 2). Hypodontia (< 6 missing teeth) occurred in 15 PCH patients and 5 controls; oligodontia (8 missing teeth) in one. In PCH on average 2.87 ±1.6 teeth were missing, and in CG 1.6 ±0.55 (statistically significant difference; p = 0.0023). Premolars were most often missing in PCH (12/16 patients); second molars (4/16) and mandibular incisors (2/16) were missing less often. For one patient from that group both premolars and second molars were affected, while for another one, premolars, second molars, and incisors were affected. In controls, premolars (3/5) and maxillary lateral incisors (2/5) were missing. Maxillary teeth were missing more often than mandibular ones. Five PCH patients had both maxillary and mandibular teeth missing. Spearman’s rho established a positive correlation between the absence of tooth buds and the age at treatment start, and sometimes also its duration, and the use of vincristine, cyclophosphamide, doxorubicin, ifosfamide etoposide, and their doses (Table 4). Furthermore, the analysis revealed that for each of these drugs the number of missing teeth increased when the used dose (correlation coefficient for vincristine: 0.2911, cyclophosphamide: 0.2795, doxorubicin: 0.2043, ifosfamide: 0.2058, etoposide: 0.2041) and treatment duration were increased (correlation coefficient: 0.2526).
Table 4 Statistically significant Spearman’s rho determining the correlation between tooth congenital disorders and the used antineoplastic treatment, age at treatment start, treatment duration, and early complications
Root resorption Tooth agenesis Microdontia DeI
D1, D2, D3 D2 and D3 DeI D1 + D2 + D3
Age at start 0.1844* 0.3600* 0.2823* 0.1981* 0.1050 0.3664*
Treatment duration 0.1520 0.3089* 0.2459* 0.2415* 0.3099* 0.4276*
Time since treatment completion 0.2459* 0.4413* 0.3462* 0.3726* 0.4801* 0.5802*
VCR 0.2517* 0.4049* 0.3746* 0.2777* 0.3748* 0.5487*
Dose 0.2327* 0.3427* 0.3517* 0.2756* 0.3322* 0.4962*
CTX 0.2866* 0.4054* 0.4029* 0.2724* 0.3702* 0.5047*
Dose 0.2796* 0.4032* 0.3992* 0.2632* 0.3678* 0.4852*
ADM 0.1601 0.3931* 0.2850* 0.2148* 0.3025* 0.4385*
Dose 0.1504 0.3722* 0.2632* 0.1990* 0.2549* 0.3942*
DTIC 0.1673 0.1817* 0.1784 0.1389 0.1036 0.2228*
Dose 0.1758 0.1843* 0.1807* 0.1544 0.1296 0.2290*
IF 0.2257* 0.4115* 0.2989* 0.2111* 0.2394* 0.3491*
Dose 0.2135* 0.4046* 0.2902* 0.2024* 0.2062* 0.3339*
MTX 0.1111 0.1530 0.1717 0.1491 0.0741 0.2111*
Dose 0.1091 0.1505 0.1737 0.1401 0.0709 0.2068*
VP-16 0.1791 0.3625* 0.2999* 0.1763* 0.1911* 0.3597*
Dose 0.1977* 0.3631* 0.3062* 0.1917* 0.1919* 0.3636*
CDDP 0.1847* 0.2641* 0.2053* 0.1009 0.3078* 0.3193*
Dose 0.1949* 0.2784* 0.2030* 0.1346 0.3497* 0.3370*
5-FLU –0.1601 –0.0863 –0.1544 –0.0716 0.3025* 0.0942
Dose –0.1302 –0.0701 –0.1255 –0.0582 0.3906* 0.1843*
VM-26 0.1778 0.2916* 0.1714 0.1749 0.1541 0.2176*
Dose 0.1795* –0.0701 0.1733 0.1748 0.1481 0.2166*
Mucositis 0.0934 0.1649 0.1050 0.0626 0.2489* 0.1303
Grade 2 0.0556 0.0865 0.0149 0.0745 0.2593* 0.0877
Grade 2, 3 0.1601 0.1694 0.2328* 0.0716 0.1245 0.2252*
Vomiting 0.1618 0.2010* 0.1767 0.0362 0.2967* 0.2379*
* statistical significance; p ≤ 0.05
Microdontia occurred only in PCH (Table 2). The number of teeth with smaller dimensions ranged between 1 and 8 (mean 4.0 ±2.26). In three patients microdontia occurred only in maxillary teeth, and in one only in mandibular teeth. Microdontia of premolars and second molars was most common (in 9/12 and 7/12 respectively, including in 4 patients in both premolars and second molars). One patient presented a reduction in tooth size in maxillary premolars and mandibular incisors. A positive correlation between microdontia and chemotherapy duration, chemotherapeutic use and its doses (VCR, CTX, ADM, IF, VP-16, CDDP, and 5-FU), vomiting and mucositis (Table 4) was established. The same factors had an impact on the number of microdontic teeth, which increased with chemotherapy duration (correlation coefficient 0.3109) and the dose of the aforementioned drugs (coefficients for vincristine: 0.3309, cyclophosphamide: 0.3617, doxorubicin: 0.2577, IF: 0.2010, etoposide: 0.1851, cisplatin: 0.3435, 5-fluorouracil: 0.4099).
A correlation was also established between DeI and age at treatment start, treatment duration, the use and dose of vincristine, cyclophosphamide, doxorubicin, ifosfamide, methotrexate, etoposide, cisplatin, and grade 3 mucositis and vomiting (Table 4).
Other congenital disorders most often included taurodontism, which occurred statistically significantly more often (p = 0.0135) in PCH than in CG (20.0% vs. 5.0%). Hypertaurodontism was diagnosed in one PCH patient, and mesotaurodontism in three of them. Hypotaurodontism occurred in other patients after chemotherapy and in controls. A positive correlation between taurodontic teeth and child age at treatment start (correlation coefficient 0.3000; p = 0.0009), and vincristine treatment (coefficient 0.2156), and its doses (coefficient 0.2096), was established.
Upon analysis of respective factors related to antineoplastic therapies, it turned out that vincristine treatment and its doses were related to all observed congenital disorders. Treatment with cyclophosphamide, doxorubicin, ifosfamide, and their doses, related to hypodontia, microdontia and root resorption, and enamel defects, also had a strongly negative impact on odontogenesis. Etoposide and cisplatin treatments were related to microdontic teeth, root resorption, and enamel defects; methotrexate use was related only to root resorption and enamel defects; and carboplatin use was related only to dentinoma prevalence and enamel defects. Early complications, such as mucositis and vomiting, promoted root resorption, reduction in tooth size, and enamel defects.
Discussion
The present study confirmed that chemotherapeutics could perturb odontogenesis, which also reflected the findings of other quoted studies.
Contrary to its results, some researchers did not discover any differences in enamel hypoplasia prevalence in children treated for neoplasms with chemotherapy or chemotherapy combined with radiotherapy and in the general population [13, 27, 50]. According to other researchers, the prevalence of enamel congenital disorders is higher in children who have undergone antineoplastic treatment [38, 51–53].
According to Oğuz et al., some chemotherapeutics may cause congenital enamel defects [36], including vincristine, vinblastine, and cyclophosphamide. In animal research (hamsters 1997), Lyaruu et al. demonstrated that actinomycin D had a negative impact on amelogenesis [26]. In tests on rats receiving intravenous vincristine and vinblastine together with other chemotherapeutics, Greaves noted the presence of growth lines in teeth, correlated with chemotherapeutic treatment duration [54]. However, Marec-Berard et al. did not establish any correlation between drug use and dose and congenital enamel defects [27]. The present study indicates a correlation between hypoplasia and the use of vincristine and methotrexate, and opacities and the use of vincristine, cisplatin, methotrexate, doxorubicin, ifosfamide, and carboplatin. Näsman et al. noted white enamel opacities in 68% of children under chemotherapy and in 29% of controls [48]. Similarly, Nunn et al. observed higher prevalence of opacities and hypoplasia in the PCH group than in controls, but those differences were not statistically significant [55]. In the Hutton study (2008), 60.2% of children in a group of 120 undergoing chemotherapy presented enamel defects. Enamel hypoplasia did not occur as a single defect in any patient [11].
Oğuz et al. established a correlation between child age at treatment start and enamel hypoplasia, which reflects the results of the present study [36]. However, Marec-Berard et al. established, upon observing 27 children treated for different stages of neuroblastoma, and contrary to the results of the present study, that treatment duration had no impact on the prevalence of congenital disorders [27].
Kinirons et al. examined 54 children a long time after they had completed chemotherapy for acute lymphoblastic leukaemia and noted that treatment duration did not have any impact on the number of teeth with congenital enamel defects. They also established that the increase in the number of permanent teeth with enamel opacities was related to remission extension [56].
Doðan et al. assessed the correlation between early complications and enamel hypoplasia (2001). Nine among 85 children treated for acute lymphoblastic leukaemia suffered from mucositis, and five presented enamel hypoplasia [52]. In the present study, complications presented as vomiting and were correlated with opacities, and as grade 2 mucositis correlated with enamel hypoplasia. These complications could lead to malnutrition in children and present secondary amelogenesis disorders.
There are few publications on the impact of chemotherapy itself, without radiation therapy, on tooth bud development and congenital abnormality development. Since chemotherapy protocols include a couple of chemotherapeutics, there is no information on the impact of the respective drugs on odontogenesis. The available research presents all the types and prevalence of dental congenital abnormalities [14, 21–24, 57]. Maciel et al. found congenital abnormalities in 80.4% of patients treated for lymphoblastic leukaemia [14]. Höltta et al. reported that 100% of children after chemotherapy presented congenital abnormalities (DeI>1) vs. 25% of controls [21]. Cubucku et al. (2012) compared the DeI in children under chemotherapy (27 children) and in those under chemo- and radiation therapy (10 children) to DeI in controls. According to their study, DeI> 1 also occurred in 100% of patients and in 12.9% of controls [57]. In the present study, congenital tooth abnormalities, visible on pantomographs, occurred more often in patients after chemotherapy than in controls. However, the percentage of PCH patients (76.7%) with congenital tooth abnormalities was lower than the ones assessed by Minicucci et al. (82.9%) [28] and by Maciel et al. (80.4%) [14], but higher than the one assessed by Kaste et al. (60.5%) [38].
Researchers present various DeI, which is probably related to different multidrug chemotherapy protocols in different neoplasms. For Höltta et al. [21], the DeI was 15.3 ±9.3 in patients under chemotherapy for lymphoblastic leukaemia and 1.8 ±3.9 in controls. These index values were similar to the one in the present study [21]. Mean DeI for Hisieh et al. (children treated for lymphoblastic leukaemia) was 24.7 ±17.8 [25], and for Cubucku et al. (children treated for lymphoblastic leukaemia) 10.8 ±11.2 [57].
In the present study, root resorption, occurring in 60% of patients after chemotherapy, was the most common congenital abnormality observed on pantomographs. In the Cubucku et al. study, congenital root abnormalities occurred more often (86.4%), but patients under chemotherapy and radiation therapy represented 27% of the treatment group [57].
Tooth agenesis or microdontia occurred slightly less often than root congenital abnormalities. The prevalence of these defects varied. Höltta assessed microdontia prevalence, in 55 children treated with high chemotherapy doses before they turned ten years old, at 44% and agenesis at 46%. According to Marec-Berrard et al., these percentages were 18% and 7% respectively [27]; to Oğuz et al., 44% and 3% [36]; to Maciel et al. [14], 50% and 25%; and to Cubucku et al., 16.2% and 13.5% [57]. In the present study, agenesis occurred in 26.67% of patients after chemotherapy, and microdontia in 21.67%. These defects most often occurred in premolars and second molars. According to Höltta et al. and Nisihmura et al., that is related to child age at treatment start, and at the same time to the stage of tooth development [21, 24, 58].
According to Nishimura et al., there existed a strong correlation between age at treatment start and the prevalence of congenital tooth abnormalities. Root resorption occurred most often in treated patients between the age of zero and 11.8 years. In the present study microdontia or tooth agenesis was not reported in patients aged eight years or older. Tooth agenesis/microdontia occurred in 66.7% of patients under the age of four and treated with standard chemotherapy and in 100% of those treated with high drug doses. In the < 4 < 8 year group, tooth agenesis and microdontia occurred respectively in 18.2 and 25% of patients [58].
The present study also established that the longer the antineoplastic treatment was, the more frequent and severe were the congenital abnormalities. Every congenital abnormality was strongly correlated to the duration of antineoplastic treatment.
Cubucku et al. [57], and Nishimura et al. [58] did not establish any correlation between conventional chemotherapy duration and odontogenesis disorders. However, Höltta et al. did not analyse the impact of antineoplastic treatment duration on the prevalence of congenital dental disorders [21, 25].
The correlation between microdontia and the number of teeth reduced in size, and early complications of antineoplastic therapies, including vomiting and mucositis, is an interesting one. It has only been assessed by Olczak-Kowalczyk and Dembowska-Bagińska; however, the studies focused on children treated with chemotherapy combined with radiation therapy [59–61].
Congenital tooth abnormalities are said to result from the direct impact of the drug on odontoblasts and from its indirect impact, including early complications of chemotherapy. Höltta assessed, in his PhD thesis, the impact of different drugs on odontoblasts and ameloblasts in hamster teeth [24]. He established that the studied drugs impaired cellular functions only when they were in use; after treatment completion ameloblast and odontoblast functions were restored.
Numerous researchers [21, 25, 27, 28] have also attempted to assess the impact of chemotherapeutics on odontogenesis and tooth formation. Heirh et al. found that most DeI values in patients treated with a combination of drugs, including cyclophosphamide, were higher than in those treated without that drug [25]. In their tests on animals, Lyaruu et al. confirmed that actinomycin D had an impact on tooth enamel and dentine formation, causing pre-odontoblast loss [28]. The assessment of the impact of doxorubicin on human dental pulp cells and fibroblasts (varying drug doses) established that this chemotherapeutic caused a considerable reduction of live cells within the dental pulp and fibroblasts [24]. Some researchers [24, 62] suggest that methotrexate does not cause any dental congenital abnormalities. Five-fluorouracil causes mild perturbations in dental structure only during drug administration; once it is no longer administered odontogenesis resumes [24]. There is no information on the impact of ifosfamide and cisplatin on tooth development.
The present study established a positive correlation between VCR, CTX, IF, and CDDP and their doses and root resorption, including its most severe forms. Vincristine, cyclophosphamide, doxorubicin, and isophosphamide presented a correlation with hypodontia, which was confirmed by Höltta’s study on hamsters.
Apart from drugs presenting a positive correlation with hypodontia, other chemotherapeutics, such as etoposide, cisplatin, and 5-fluorouracil, had an impact on microdontia. These results were similar to the ones obtained by other researchers [21, 24, 48]. However, etoposide, cisplatin, and ifosfamide were not listed among the drugs whose adverse reactions could cause dental abnormalities, and therefore further studies seemed necessary.
Maciel et al. noted higher prevalence of taurodontic teeth in patients after treatment with solely chemotherapeutics, compared to controls (7.1% vs. 5.3%). However, these differences were not statistically significant [14]. In the present study, the prevalence of taurodontism was statistically significantly higher in patients after chemotherapy than in controls (20% vs. 5%). A positive correlation between taurodontic teeth and child age at treatment start and vincristine treatment and dose was established. No information is available on the impact of respective chemotherapeutics on the formation of dentinoma and taurodontic teeth. The aforementioned impact of vincristine on pre- and odontoblasts, leading to perturbations in dentin formation, and on ameloblasts explains the results of the present study.
In conclusion, antineoplastic chemotherapy in children and adolescents promotes dentinoma and congenital tooth abnormalities, especially hypodontia, microdontia, root resorption, taurodontism, and congenital enamel defects. Multidrug chemotherapy including cyclophosphamide, doxorubicin, cisplatin, and vincristine has a particularly negative impact on teeth, which increases increases with the increase of the dose, treatment duration, and the severity of early complications, such as mucositis and vomiting.
The authors declare no conflict of interest.
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Contemp Oncol (Pozn)Contemp Oncol (Pozn)WOContemporary Oncology1428-25261897-4309Termedia Publishing House 2890510.5114/wo.2016.64604Original PaperThe performance of tele-cervicography for detection of preinvasive and invasive disease of the uterine cervix as an adjunctive test to Pap smears Nam Kyehyun 1Kim Soo-Nyung 2Sim Seung-hyuk 2Han Seijun 31 Department of Obstetrics and Gynecology, Soonchunhyang University Hospital, Bucheon, South Korea2 Konkuk University Medical Center, Seoul, South Korea3 Chosun University Hospital, Gwangju, South KoreaAddress for correspondence: Soo-Nyung Kim, Konkuk University Medical Center, 4-12 Hwayang-dong, Gwangjin-gu, 143-729 Seoul, Korea (South). e-mail: snkim@chol.com20 12 2016 2016 20 5 402 406 10 11 2014 11 6 2015 Copyright: © 2016 Termedia Sp. z o. o.2016This is an Open Access article distributed under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International (CC BY-NC-SA 4.0) License, allowing third parties to copy and redistribute the material in any medium or format and to remix, transform, and build upon the material, provided the original work is properly cited and states its license.Aim of the study
To evaluate the diagnostic capacity of tele-cervicography for the detection of cervical neoplasia as an adjunctive test with Papanicolaou (Pap) smears.
Material and methods
Pap smear and tele-cervicography were performed on each subject. Histologic results were obtained for all patients.
Results
Of the 863 females who had a tele-cervigram, 252 (29.2%) had a positive result. Of the 60 histologically confirmed cases of high-grade squamous intraepithelial lesions (HSILs), 56 (93.3%) were detected by tele-cervicography, including 16 (26.7%) with a positive grade of 1 and 40 (66.7%) with a positive grade of 2. With the positive threshold of tele-cervicography set as any positive grade (P0 to P3), the overall sensitivity was 94.0% (95% CI: 88.0–97.3%), the specificity was 80.9% (95% CI: 80.0–81.5%), and the positive likelihood ratio was 4.94 (95% CI: 4.23–5.77) for the detection of HSILs or cancer. The combination of tele-cervicography with Pap smear testing for the detection of HSILs or cancer resulted in an increase in sensitivity from 84.6% (Pap only: cutoff = atypical squamous cells of undetermined significance or more severe) to 98.3% (Pap plus tele-cervicography: cutoff = P0 or more severe).
Conclusions
The sensitivity of tele-cervicography was higher than that of cytology for the detection of cervical neoplasia, and combining the two tests increased the sensitivity. Tele-cervicography can be considered a useful complementary tool to cytology.
cervicographycervical cancercervical neoplasiascreening
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Introduction
It is well recognised that cytological screening to detect preinvasive and early invasive cancer of the uterine cervix has led to a dramatic decline in the incidence of cervical cancer mortality in several countries [1]. The incidence of cervical cancer has fallen by 50% or more since the introduction of Papanicolaou (Pap) smear screening in countries that perform cervical cancer screening [2]. The false-negative rates of Pap smears are considerable, ranging from 15% to 30% for high-grade lesions [3]. False-negative rates for invasive cervical cancer can be even higher, approaching 50% in some series. Concerns regarding errors in conventional Pap smears have motivated some researchers to evaluate alternate or adjunctive screening methods [4].
One adjunctive screening method is cervicography. In 1981, Adolf Stafl described a cervicography method and recommended its use as an adjunctive tool with Pap smears for the primary screening of cervical cancer [5]. Cervicography can be used in combination with cytological examination to screen the general population. The higher sensitivity of cervicography compared with a Pap smear was confirmed in other series, and led to the recommendation of cervicography as a complementary test to cytology [6].
The prototype cervicography system was equipped with a 35-mm camera and film [5]. This process, from taking the photographs to reporting the results to physicians, including the development of films, mounting the slides, and reading in the dark room, was both complex and laborious. Recently, the tele-cervicography system was developed. The entire cervicography process was conducted through the Internet. The present study aimed to evaluate tele-cervicography as a primary screening method and as an adjunct to the Pap smear for the early detection of preinvasive and invasive cancer of the uterine cervix. This study focused on the performance of tele-cervicography, omitting the inconvenience of proto-type cervicography.
Material and methods
Patients
Cervical cytology and tele-cervicography were performed on 3065 female patients at the gynaecological cancer clinic at Konkuk University Hospital between August 2005 and January 2010. Of the 3065 females, 863 were eligible for analysis. The inclusion criteria were asymptomatic non-pregnant females who presented for gynaecological examination. Females with a previous abnormal Pap smear within the past 12 months, who received treatment for CIN, or who had undergone a total hysterectomy before the examination were excluded. Institutional approval was obtained from the Ethics Committee for Medical Research of the Hospital of Konkuk University. Because of the retrospective nature of the study, the requirement for informed consent was waived.
Conventional Pap smear
A Pap smear was carried out using a wooden Ayre spatula in combination with a cytobrush (Medland, Seoul, Korea). All specimens were stained using the Papanicolaou method and were classified according to the Bethesda system. The positive cut-off grades of the Pap smear test were classified as ASCUS or more severe and LSIL or more severe.
The tele-cervicography procedure
After collecting the cytological specimen, two tele-cervigram images were obtained. Acquisition of the tele-cervigram images was as for conventional cervigrams. Firstly, 5% acetic acid was applied to the cervix after removing mucus or discharges. Next, the first image was obtained 30 seconds after acetic acid application. A second acetic acid application to the cervix was carried out, and another image was taken after 15 seconds. The images were transmitted to a server via the Internet for immediate evaluation. Transmitted images were evaluated on a video monitor. The tele-cervigrams were evaluated by certified evaluators who had passed the level II or higher test of the National Testing Laboratories worldwide (St Louis, MO, USA) for evaluation of cervicography (Fig. 1). The criteria for reading the tele-cervigrams were as for conventional cervicography diagnostic criteria approved by National Testing Laboratories worldwide, as noted in Table 1. The positive cut-off grades were classified as atypical or more severe and P0 or more severe.
Fig. 1 The internet network system of digital tele-cervicography
Table 1 Tele-cervicography diagnostic classification
Classification Explanation
Not referred for colposcopy
Negative
Atypical
Technically defective No lesion observed
A trivial lesion inside or outside the transformation zone is visible, but colposcopy is not recommended because of the benign appearance or site of the lesion
The cervigram slide is not adequate
Referred for colposcopy
Positive 0 (P0)
Positive 1 (P1)
Positive 2 (P2)
Positive 3 (P3) Probably normal, but colposcopy is preferable to rule out serious neoplasia
Compatible with trivial disease, but colposcopy is recommended because part of the lesion extends into the canal or compatible with a low-grade squamous intraepithelial lesion, flat condyloma, and exophytic condyloma
Compatible with a high-grade squamous intraepithelial lesion
Compatible with cancer
The above classification was released on January 1, 1995 by National Testing Laboratories worldwide. The current terminology was applied to all tele-cervigram classifications in this study.
Data analysis
The sensitivity, specificity, and positive likelihood ratio of tele-cervicography were calculated using the biopsy result as the ‘gold standard’. Likelihood ratios are a useful and practical way of expressing the power of a diagnostic test [7], and are independent of disease prevalence. Two different definitions of disease were used as targets for screening: (1) disease is an HSIL or cancer (vs. a normal, equivocal, or low-grade squamous intraepithelial lesion); (2) disease is an LSIL, an HSIL, or cancer (vs. a normal or equivocal lesion). Two thresholds to define a positive tele-cervigram result were examined for analytical purposes, including (1) a positive grade of P0, P1, P2, or P3 (vs. an atypical or a negative tele-cervigram result) and (2) an atypical or a more severe positive (vs. negative) tele-cervigram result. Analyses of sensitivity and specificity were conducted using standard contingency table methods. Tables were stratified by age. Tele-cervicography was directly compared with conventional cytological screening based on the threshold level for ASCUS or more severe and LSIL or more severe.
Statistical analysis
The data were computerised and analysed using SPSS ver. 19 (SPSS, Inc., Chicago, IL, USA). The diagnostic accuracy of each test was calculated based on the sensitivity, specificity, and the positive likelihood ratio and the EpiMax Table Calculator (http://www.healthstrategy.com). The sensitivity of cytology and tele-cervicography for the detection of HSIL or cancer was analysed using McNemar’s test (http://vassarstats.net/propcorr.htm). All p-values presented are two-tailed; a value of p < 0.05 was taken to indicate statistical significance.
Results
Patients’ characteristics
The average age of the 863 patients was 48.3 ±10.5 years (range: 23–85 years), and their characteristics are summarised in Table 2. Pap smear, tele-cervigram, and biopsy results are summarised in Table 2.
Table 2 Patients’ characteristics (n = 863)
Characteristic Value
Age (years) 48.3 ±10.5 (23–85)
Age group < 50 years
≥ 50 years 470
393
Pap cytology WNL
ASCUS
AGC
ASC-H
LSIL
HSIL
Cancer 500 (57.9)
144 (16.7)
4 (0.5)
6 (0.7)
125 (14.5)
61 (7.1)
23 (2.7)
Tele-cervicography results Negative
Atypical
Positive 0
Positive 1
Positive 2
Positive 3 512 (59.3)
99 (11.5)
12 (1.4)
147 (17.0)
66 (7.6)
27 (3.1)
Biopsy results Cervicitis
Koilocytosis
CIN 1
CIN 2
CIN 3
Cancer 551 (63.8)
13 (1.5)
182 (21.1)
7 (0.8)
53 (6.1)
57 (6.6)
WNL – within normal limits; ASCUS – atypical squamous cells of undetermined significance; AGC – atypical glandular cells; ASC-H – atypical squamous cells, cannot exclude HSIL; LSIL – low-grade squamous intraepithelial lesion; HSIL – high-grade squamous intraepithelial lesion; CIN – cervical intraepithelial neoplasia
Diagnostic potential of tele-cervicography and the Pap smear
The distribution of pathologic diagnosis according to the tele-cervigram result is presented in Table 3. Of the 863 females who had a tele-cervigram, 252 (29.2%) had a positive result. Fifty-four cases (94.7%) of 57 invasive cancers were detected by tele-cervicography. Of the histologically confirmed cases of HSILs, 56 (93.3%) were detected by tele-cervicography, including 16 (26.7%) with a positive 1 tele-cervigram and 40 (66.7%) with a positive 2 tele-cervigram (Table 3). The sensitivity, specificity, and positive likelihood ratio of tele-cervicography for the detection of HSILs or cancer are presented in Table 4. With a positive threshold of tele-cervicography as any positive result (P0 to P3), the overall sensitivity of the tele-cervigram was 94.0% (95% CI: 88.0–97.3%), the specificity was 80.9% (95% CI: 80.0–81.5%), and the positive likelihood ratio 4.94 (95% CI: 4.23–5.77) (Table 4).
Table 3 Distribution of final pathology results by tele-cervicography
Tele-cervicography result* Final pathology
Normal (No, %) Koilocytosis (No, %) CIN 1 (No, %) CIN 2 (No, %) CIN 3 (No, %) Cancer (No, %) Total (No, %)
Negative 487 (88.4) 1 (7.7) 23 (12.6) 0 (0.0) 0 (0.0) 1 (1.8) 512 (59.3)
Atypical 39 (7.1) 5 (38.5) 49 (26.9) 0 (0.0) 4 (7.5) 2 (3.5) 99 (11.5)
Positive 0 2 (0.4) 0 (0.0) 3 (1.6) 0 (0.0) 0 (0.0) 7 (12.3) 12 (1.4)
Positive 1 22 (4.0) 7 (53.8) 100 (54.9) 5 (71.4) 11 (20.8) 2 (3.5) 147 (17.0)
Positive 2 0 (0.0) 0 (0.0) 7 (3.8) 2 (28.6) 38 (71.7) 19 (33.3) 66 (7.6)
Positive 3 1 (0.2) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 26 (45.6) 27 (3.1)
Total 551 13 182 7 53 57 863 (100.0)
CIN – cervical intraepithelial neoplasia.
The tele-cervicography classification scheme is provided in Table 1.
Table 4 Sensitivity and specificity of tele-cervicography for the detection of HSILs or cancer
No. with HSILs or cancer Total Threshold level
Referred for tele-cervicography if atypical or more severe Referred for tele-cervicography if P0 or more severe
Sensitivity (%) Specificity (%) Positive LR Sensitivity (%) Specificity (%) Positive LR
Overall 117 863 99.1 68.4 3.15 94.0 80.9 4.94
Age group < 50 years 69 470 99.3 57.9 2.36 95.7 75.6 3.91
≥ 50 years 48 393 97.9 80.9 5.12 91.7 87.2 7.19
HSIL – high-grade squamous intraepithelial lesion; LR – likelihood ratio
Diagnostic potential of the Pap smear
The sensitivity of the Pap smear for the detection of HSILs or cancer using a threshold of ASCUS or more severe was 84.6% (95% CI: 77.0–90.0%), the specificity was 64.4% (95% CI: 61.1–68.0%), and the positive likelihood ratio was 2.39 (95% CI: 2.112–2.707) (Table 5). Tele-cervicography combined with the Pap smear for the detection of HSILs or cancer showed an increased sensitivity from 84.6% of Pap only (ASCUS or more severe) to 98.3% (95% CI: 94.0–99.5%) (Pap plus tele-cervicography [P0 or more severe]) (Table 6). Regarding the detection of LSIL or more severe lesions, tele-cervicography showed similar results when used in combination with Pap cytology (Table 6).
Table 5 Sensitivity and specificity of Pap cytology for the detection of HSILs or cancer
No. with HSIL or cancer Total Threshold level
Positive Pap cytology if ASCUS or more severe Positive Pap cytology if LSIL or more severe
Sensitivity (%) Specificity (%) Positive LR Sensitivity (%) Specificity (%) Positive LR
Overall 117 863 84.6 64.6 2.39 60.7 81.5 3.26
Age group < 50 years 69 470 84.1 56.1 1.91 49.3 77.1 2.15
≥ 50 years 48 393 85.4 74.5 3.34 77.1 86.7 5.78
ASCUS – atypical squamous cells of undetermined significance; LSIL – low-grade squamous intraepithelial lesion; LR – likelihood ratio
Table 6 Sensitivity and specificity of Pap cytology combined with tele-cervicography for the detection of LSILs or more severe lesions and HSILs or cancer
Sensitivity (%) Specificity (%) Positive likelihood ratio
HSILs or cancer (n = 117)
Pap smear only (ASCUS or more severe) 84.6 64.6 2.39
Pap + Tele-cervicography (P0 or more severe) 98.3 60.6 2.49
LSIL or more severe (n = 312)
Pap smear only (ASCUS or more severe) 85.6 82.6 4.91
Pap smear + Tele-cervicography (P0 or more severe) 97.1 80.6 5.05
ASCUS – atypical squamous cells of undetermined significance; LSIL – low-grade squamous intraepithelial lesion; HSIL – high-grade squamous intraepithelial lesion.
Discussion
Telemedicine can be applied to healthcare for many people, particularly those living outside of urban areas [8]. The application of telemedicine to colposcopy or telecolposcopy has been reported and suggests that telecolposcopy can enable distant colposcopy experts to remotely examine females with cervical neoplasia [9, 10]. Telecolposcopy using digitalised colposcopic images can be applied to colposcopy quality control by remote review [11]. Tele-cervicography is one example of digital cervicography. Our system is different from digital cervicography of previous papers. We designed Internet-based software for the evaluation of digitalised cervical images. Soon after being obtained by digital cervicography, the cervical images were sent to a certified evaluator at a distant location through an Internet-based central server.
In our study, the tele-cervigram results were positive (P0 to P3) in 252 (29.2%) of 863 patients. This rate is higher than the positive rate of cervicography among the screened general population, which ranges from 3.1% to 10.6% [4, 6, 12]. The cause may be that the target population was different, and our study was not designed for cervicography screening. The goal of our study was to evaluate the diagnostic capacity of tele-cervicography.
Our results showed that the final pathologic distribution of 66 females with a positive 2 comparable with CIN 2/3 was 7 (10.6%) with CIN 1, 40 (60.6%) with CIN 2/3, and 19 (28.8%) with cancer. Of 27 females with a positive 3 comparable with cancer, 26 (96.3%) were diagnosed with cancer. Our results are similar to those of previous reports of the diagnostic accuracy of cervicography results [4, 13]. The increasing tendency of diagnostic accuracy with increasing cervical pathology severity is confirmed by previous colposcopy studies [14, 15].
The overall sensitivity and specificity of tele-cervicography for the detection of HSILs or cancer by the threshold of any positive tele-cervigram (P0 to P3) were 94.0% and 80.9%, respectively. The detection of high-grade lesions by cervicography is superior to that of low-grade lesions, as has been reported previously [16]. The sensitivity is higher than that in other studies, ranging from 49.5% to 58.2% in screening the general population [4, 12].
The significant increase in sensitivity that resulted from combining the two screening tools in this study has important implications for the screening program in terms of avoiding false-negative diagnosis of fatal cervical cancer. The combination of the Pap smear and tele-cervicography increased the sensitivity from 84.6% to 98.3% for the detection of HSILs or cancer, similar to those in previous reports [17–20]. The combination of tele-cervicography with Pap smear will decrease the false-negative rate of Pap smear alone for cervical cancer screening.
A limitation of this study was that the population was not a general screening population; thus the results do not represent screening characteristics. Additionally, to analyse the diagnostic accuracy of tele-cervicography, the exclusion of technically defective cases was not representative of the general practice of cervicography. The advantages of this study were that all subjects had results of cervical biopsy, revealing the diagnostic capacity of the Pap smear and tele-cervicography at one institution.
In conclusion, our data suggest that tele-cervicography has a high-quality diagnostic capacity for the detection of uterine cervical neoplasia, provides high-resolution images, and allows rapid interpretation through Internet-based software. This study suggests that tele-cervicography can offer colposcopy services to medically underserved females by remotely located expert colposcopists. A large-scale trial in an unscreened population should be carried out more rigorously to determine the sensitivity of this new device and assess its potential as a screening tool.
The authors declare no conflict of interest.
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References
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Contemp Oncol (Pozn)Contemp Oncol (Pozn)WOContemporary Oncology1428-25261897-4309Termedia Publishing House 2890610.5114/wo.2016.64605Original PaperA retrospective evaluation of associations between chronic obstructive pulmonary disease, smoking, and efficacy of chemotherapy and selected laboratory parameters in patients with advanced non-small cell lung cancer Czyżykowski Rafał 1Nowak Dariusz 2Janiak Anna 1Włodarczyk Anna 2Sarniak Agata 2Krakowska Magdalena 1Potemski Piotr 11 Chemotherapy Department, Mikołaja Kopernika Memorial Hospital in Łódź, Medical University of Lodz, Lodz, Poland2 Chair of Experimental and Clinical Physiology, Medical University of Lodz, Lodz, PolandAddress for correspondence: Rafał Czyżykowski, Chemotherapy Department, Mikołaja Kopernika Memorial Hospital in Lodz, Medical University of Lodz, Pabianicka 62, 93-513 Lodz, Poland. e-mail: rafal.czyzykowski@wp.pl20 12 2016 2016 20 5 407 413 30 4 2015 22 6 2016 Copyright: © 2016 Termedia Sp. z o. o.2016This is an Open Access article distributed under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International (CC BY-NC-SA 4.0) License, allowing third parties to copy and redistribute the material in any medium or format and to remix, transform, and build upon the material, provided the original work is properly cited and states its license.Aim of the study
To was to determine the impact of chronic obstructive pulmonary disease (COPD) and active smoking on the efficacy of chemotherapy and complete blood count (CBC) in patients with non-small cell lung cancer (NSCLC).
Material and methods
The retrospective evaluation included 50 patients with stage IIIB–IV NSCLC, who started cisplatin-based chemotherapy. Peripheral blood CBC values were collected for testing before chemotherapy and after the first and third cycles.
Results
COPD was diagnosed in 49% of patients, while 42% of those enrolled were current smokers. Current smoking (p = 0.92) and COPD (p = 0.91) status did not affect the response to treatment. The non-COPD population presented a significantly higher pretreatment absolute lymphocyte count (ALC) than the COPD population (2.31 vs. 1.81 × 109/l; p = 0.0374). Also, only the non-COPD group demonstrated an elevated absolute monocyte count (AMC) following the first and third cycles of chemotherapy (p = 0.004). In current smokers, pretreatment values for white blood cells (WBC), absolute neutrophil count (ANC), and platelets (PLT) were higher than in the ex-smoker population (WBC 9.94 vs. 8.7 (× 109/l); p = 0.01; ANC 6.47 vs. 5.61 (× 109/l); p = 0.037; PLT 316 vs. 266 (× 109/l); p = 0.049). Ex-smokers demonstrated AMC level elevation after the first cycle of chemotherapy and PLT level elevation after the third cycle, while current smokers also demonstrated an early decrease in LMR.
Conclusions
COPD and smoking induce chronic systemic inflammation and oxidative stress, which influence the results of standard laboratory tests, but do not change the response rate of lung cancer on chemotherapy.
non-small cell lung cancerchronic obstructive pulmonary diseasesmokingchemotherapy
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Introduction
Lung cancer is the most common newly-diagnosed malignancy other than non-melanoma skin cancer, and the leading cause of cancer-related death worldwide. In 2012, 1.8 million people developed lung cancer and approximately 1.6 million died because of it [1]. The following year, lung cancer was detected in about 21,000 patients in Poland, and about 22,000 died. Non-small cell lung cancer (NSCLC) accounts for 85% of all lung cancers and has a strong aetiological association with smoking. About 10–20% of chronic smokers develop lung cancer, and about 20% of smokers suffer from chronic obstructive pulmonary disease (COPD). Cigarette smoking generates chronic inflammation in the airways and systemic oxidative-stress reactions. The pro-inflammatory and immunosuppressive properties of cigarette smoke impair the immune response [2]. Inflammation seems to play a crucial role in the development and progression of many tumours by promotion of proliferation, cell survival, angiogenesis, and migration [3].
The prognosis in NSCLC is poor, with only an 18% five-year survival rate observed in the general population in the USA [4]. As detection is usually quite late, the tumours are found to be in stages III or IV for 2/3 patients with newly-diagnosed lung malignancy. Standard treatment for this population involves systemic therapy: induction chemotherapy in stage IIIA, chemoradiotherapy (concurrent or sequential) in stage IIIB, or palliative systemic treatment when distant metastases are present. Epidermal growth factor receptor (EGFR) activating mutations are present in 10% of Caucasians [5], whereas EML4-ALK translocation is present in 2–3% of the non-Asian NSCLC population [6, 7]. As most cases of NSCLC do not present a defined target for molecular orientated therapy, platinum-based chemotherapy is the standard approach in the treatment of lung cancer. The objective response rate (ORR), defined as a complete or partial response for cytostatic treatment of advanced disease, ranges from 30% to 40%.
Lung cancer prognosis is connected with tumour-related (stage, grade) and host-related factors. Established adverse clinical prognostic factors in advanced NSCLC are weight loss and poor performance status, which are also negative predictive factors of response to chemotherapy. Although the interaction between the immune system and cancer could play a crucial role in malignancy progression, the relationship remains poorly understood. As the morbidity and mortality rates are so high, it is important to explore the mechanisms that could modify the disease course and sensitivity to systemic treatment.
Because many anti-cancer drugs exert their activity by free radical-mediated mechanisms [8], COPD-associated oxidative stress and inflammation may influence the efficacy of chemotherapy. In addition, in vitro and in vivo studies indicate that cigarette smoking worsens the response of cancer to chemotherapy [9].
The purpose of this study was to investigate the impact of COPD and active smoking on the efficacy of chemotherapy and on complete blood count (CBC) in patients with advanced NSCLC, with regard to systemic inflammatory response and oxidative stress.
Material and methods
Population
Retrospective evaluation was carried out using the medical documentation of 50 patients with NSCLC classified as stage III or IV, who began chemotherapy at the Department of Chemotherapy, Medical University of Lodz, in the Copernicus Memorial Hospital of Lodz from 2013 to 2014. The analysis included only patients treated with cisplatin-based chemotherapy doublets, with gemcitabine or vinorelbine as a second drug, and with a present smoking status or a known history of smoking.
COPD was confirmed by spirometry: a positive result was indicated when the ratio of post-bronchodilator forced expiratory volume in one second (FEV1) to forced vital capacity (FVC) was less than 0.7, as given in the Global Initiative for Chronic Obstructive Lung Disease (GOLD) guidelines
Patient characteristics included demographic data (age, sex), tumour response to treatment, complete blood cell count (CBC), and clinicopathological features: subtype of NSCLC, histological grade, performance status, weight loss, FEV1 value, FEV1/FVC ratio, and smoking status and number of pack-years in smokers. Tumour response to treatment was assessed after 2–3 cycles of chemotherapy, based on the rules established by the RECIST 1.1 (Response Evaluation Criteria in Solid Tumours). In two cases, disease progression (PD) was established based only on clinical presentation. The recruitment was approved by the Medical University of Lodz Bioethics Committee (RNN 45/12/KE and 46/12/KE).
Assessment of blood tests
The initial CBC from peripheral blood was measured before the first treatment cycle. During treatment, CBC was assessed every three weeks (with tolerance from –3 to +8 days) on day one of each cycle before treatment administration. Blood tests were performed by the Synevo laboratory, Copernicus Memorial Hospital, Lodz; spirometry (in 37 prospective cases) was performed using a MasterScreen Body (JAEGER) in the Chair of Experimental and Clinical Physiology, Medical University of Lodz.
Statistical analysis
All statistical analyses were performed with StatsDirect software (StatsDirect Ltd., Altrincham, UK).
The Friedman test was used to assess the significance of changes in blood parameters during treatment. The comparisons of baseline parameters between different groups were assessed using the χ2 test or Fisher’s exact test as appropriate, or the Mann-Whitney test. A p-value < 0.05 was considered statistically significant.
Results
Among 50 patients enrolled in the analysis, spirometry was assessed in 43 of them. COPD was diagnosed in 21 of those examined (48.8%), with GOLD stage 1 identified in nine, stage 2 in seven, and stage 3 in three cases. No data about COPD stage was given in two cases. Table 1 summarises the clinical characteristics of the study population according to COPD status.
Table 1 Demographical and clinical characteristics of the study population with COPD and no-COPD subgroups
n Age (years) median Sex M/F Smoking Y/N/never DCC median Pack-years median Stage III/IV Subtype nonS/S/U PS 0/1/2 weight loss > 10% (Y/N) FEV1 (%) median FVC (%) median
All patients 50 62 30/20 21/27/2 0 38 18/32 20/22/8 13/30/7 14/36 81.85 96.5
COPD 21 62 12/9 9/12/0 0 40 6/15 8/9/4 5/11/5 6/15 68.9 98.15
No-COPD 22 62 12/10 9/11/2 0 30 11/11 8/10/4 6/14/2 6/16 88.8 93
p value 0.8 0.86 0.6 0.97 0.37 0.15 > 0.99 0.49 0.92 0.03 0.67
COPD – chronic obstructive pulmonary disease; n – number of participants; M – male, F – female, DCC – daily cigarette consumption, Y – yes; N – no; nonS – non-squamous carcinoma (adenocarcinoma or large-cell carcinoma); S – squamous carcinoma; U – unable to assess, PS – ECOG performance status
At the start of chemotherapy, 21 patients (42%) continued to smoke, 27 (54%) reported quitting smoking in the past; two patients had never smoked (Table 2).
Table 2 Demographical and clinical characteristics of the study: smokers and ex-smokers subgroups
n
Age (years) median Sex M/F DCC median Pack-years median Stage III/IV Subtype nonS/S/U PS 0/1/2 Weight loss > 10% (Y/N)
Smokers 21 62 15/6 10 40 6/15 7/10/4 4/14/3 12/9
Ex-smokers 29 62 15/14 0 30 11/18 13/12/4 9/16/4 2/27
p value 0.54 0.16 < 0.0001 0.09 0.49 0.74 0.66 < 0.0001
COPD – chronic obstructive pulmonary disease; n – number of participants; DCC – daily cigarette consumption; M – male; F – female; nonS – non-squamous carcinoma (adenocarcinoma or large-cell carcinoma); S – squamous carcinoma; U – unable to assess; PS – ECOG performance status
When data collection was complete, four patients continued chemotherapy – each patient received at least one cycle. Response to treatment was assessed in 45 cases. One patient died due to toxicity before computed tomography examination. In total, a partial response was demonstrated in 18 (40%) patients, stable disease in 19 (42%), and cancer progression in eight (18%).
No-COPD vs. COPD
Partial remission was observed in seven of the 18 patients eligible for response assessment in the COPD group compared to 10 of the 20 patients without COPD. Stable disease occurred in 8/18 COPD patients and 7/20 non-COPD patients. Disease progression was observed in 3/18 COPD and 3/20 non-COPD patients. The differences were non-significant (p = 0.91).
The non-COPD population demonstrated a higher pretreatment absolute lymphocyte count (ALC) than the COPD population (2.31 vs. 1.81 × 109/l; p = 0.0374). An insignificant tendency for increased ALC was found in the non-COPD patients after the first cycle of chemotherapy (p = 0.053) but not in the COPD group. Similarly, the non-COPD group also demonstrated elevated absolute monocyte count (AMC) after the start of the treatment and after the third cycle (both p = 0.004). Both populations demonstrated NLR reduction after the fist and third cycles, LMR reduction after the thirrd cycle, and PLR enlargement after the first cycle. A detailed comparison is presented in Table 3.
Table 3 Differences of analysed parameters (median value and change after treatment) depending on variables and time point during chemotherapy
Entire population No-COPD COPD No-COPD vs. COPD Smokers Ex-smokers Smokers vs. ex-smokers
WBC (× 109/l) 9.27 9.65 8.83 NS 9.94 8.7
p = 0.01
post 1c. vs. 0 ↓ (p < 0.0001) ↓ (p = 0.0002) ↓ (p = 0.001) ↓ (p = 0.002) ↓ (p < 0.0001)
post 3c. vs. 0 ↓ (p <0.0001) ↓ (p = 0.0001) ↓ (p = 0.001) ↓ (p = 0.001) ↓ (p < 0.0001)
neutrophils (× 109/l) 5.84 6.275 5.66 NS 6.47 5.61
p = 0.037
post 1c. vs. 0 ↓ (p < 0.0001) ↓ (p < 0.0001) ↓ (p < 0.0001) ↓ (p < 0.0001) ↓ (p < 0.0001)
post 3c. vs. 0 ↓ (p < 0.0001) ↓ (p < 0.0001) ↓ (p < 0.0001) ↓ (p < 0.0001) ↓ (p < 0.0001)
lymphocytes (× 109/l) 2.05 2.31 1.81
p = 0.0374 2.05 2.03 NS
post 1c. vs. 0 NS ↑ NS (p = 0.053*) NS NS ↑ NS (p = 0.08)
post 3c. vs 0 NS NS NS NS NS
monocytes (× 109/l) 0.86 0.9 0.85 NS 0.88 0.85 NS
post 1c. vs. 0 ↑ (p = 0.005) ↑ (p = 0.004*) NS ↑ NS (p = 0.059*) ↑ (p = 0.004*)
post 3c. vs. 0 ↑ (p = 0.01) ↑ (p = 0.004*) NS ↑ NS (p = 0.059*) ↑ NS (p = 0.087*)
eosynocytes (× 109/l) 0.16 0.195 0.14 NS 0.2 0.16 NS
post 1c. vs. 0 ↓ (p = 0.0001) ↓ (p = 0.002) ↓ (p = 0.008) ↓ (p = 0.002) ↓ (p = 0.003)
post 3c. vs. 0 ↓ (p < 0.0001) ↓ (p = 0.001) ↓ (p = 0.025) ↓ (p = 0.001) ↓ (p = 0.001)
basocytes (× 109/l) 0.04 0.045 0.04 NS 0.05 0.04 NS
post 1c. vs. 0 NS NS NS NS NS
post 3c. vs. 0 ↓ (p = 0.046**) NS NS NS NS
haemoglobin (g/dl) 13.2 13.65 12.8 NS 12.8 13.9 NS
post 1c. vs. 0 ↓ (p < 0.0001) ↓ (p < 0.0001) ↓ (p = 0.008) ↓ (p = 0.0002) ↓ (p < 0.0001)
post 3c. vs. 0 ↓ (p < 0.0001) ↓ (p < 0.0001) ↓ (p < 0.0001) ↓ (p < 0.0001) ↓ (p < 0.0001)
PLT (× 109/l) 304 304 298 NS 316 266
p = 0.049
post 1c. vs. 0 ↑ (p < 0.0001) ↑ (p < 0.0001) ↑(p = 0.027*) ↑ (p = 0.001) ↑ (p < 0.0001)
post 3c. vs. 0 NS NS NS NS ↑ (p = 0.046)
NLR 28.5 2.71 2.97 NS 3.3 2.8 NS
post 1c. vs. 0 ↓ (p < 0.0001) ↓ (p < 0.0001) ↓ (p < 0.0001) ↓ (p < 0.0001) ↓ (p < 0.0001)
post 3c. vs. 0 ↓ (p < 0.0001) ↓ (p < 0.0001) ↓ (p < 0.0001) ↓ (p < 0.0001) ↓ (p < 0.0001)
LMR 2.47 2.54 2.28 NS 2.20 2.57 NS
post 1c. vs. 0 ↓ (p = 0.018) NS NS ↓ (p = 0.045) NS
post 3c. vs. 0 ↓ (p = 0.0001) ↓ (p = 0.016*) ↓ (p = 0.005) ↓ (p = 0.019) ↓ (p = 0.003)
PLR 146.91 136.19 162.38 NS 161.63 137.02 NS
post 1c. vs. 0 ↑ (p < 0.0001) ↑ (p = 0.002) ↑ (p = 0.016*) ↑ (p = 0.016) ↑ (p < 0.0001)
post 3c. vs. 0 NS NS NS NS NS
* without significant change of values in general Friedman test: only one value tends to be different to another (p: 0.05–0.1)
** without significant change of values in general Friedman test: only one value tends to be different to another (p ≥ 0.1)
0 – baseline; 1c. – first cycle of chemotherapy; 3c. – third cycle of chemotherapy; WBC – white blood cells; PLT – platelets; UA – uric acid; LDH – lactate dehydrogenase; NLR – neutrophil-to-lymphocyte ratio; LMR – lymphocyte-to-monocyte ratio; PLR – platelet-to-lymphocyte ratio; NS – non-significant; ↑ – increase; ↓ – decrease. COPD – chronic obstructive pulmonary disease; NS – not statistically significant
Smokers vs. ex-smokers
Of the patients eligible for response assessment, partial remission was documented in 7 of the 19 members of the current smoker population, and in 11 of the 26 ex-smokers. Stable disease was observed in 8/19 smokers and 11/26 ex-smokers. Disease progression was seen in 4/19 of smokers and 4/26 of ex-smokers. The differences were non-significant (p = 0.92).
Pretreatment scores for WBC, absolute neutrophil count (ANC), and platelet number (PLT) were higher in the smoker than in the ex-smoker population: WBC 9.94 vs. 8.7 (× 109/l); p = 0.01; ANC 6.47 vs. 5.61 (× 109/l); p = 0.037; PLT 316 vs. 266 (× 109/l); p = 0.049. Increases in PLT level following the third cycle were observed in the ex-smokers but no change was observed in the smokers. A non-significant trend (p = 0.08) towards early ALC increase was noted only in the ex-smokers. Early LMR decrease was demonstrated only in active smokers. The results are presented in Table 3.
Differences in laboratory parameters between the groups depending on response to treatment
Baseline AMC was significantly higher in the PR group than in the PD group: 0.97 vs. 0.65 (× 109/l) (p = 0.021). A non-significant trend towards higher WBC and ANC was observed in the PR group: 9.58 vs. 7.56 (× 109/l) for WBC (p = 0.078); 6.39 vs. 4.67 (× 109/l) for ANC (p = 0.064). No other differences were observed in baseline parameters (Table 4). Contrary to patients with PR or SD, the PD group demonstrated no significant decrease in WBC after cycles 1 and 3, no decrease in ANC or NLR (after 1 cycle), and no early increase of PLT or PLR during chemotherapy. On the other hand, a noticeable decrease of PLR was observed after three cycles as a result of elevated ALC in the poor response group. AMC elevation and consequent LMR reduction was reported only in the SD group, while greater PLR was observed in three cycles of treatment only in the PR group.
Table 4 Differences of analysed parameters (median value and change after treatment) depending on tumour response and time point during chemotherapy
PR SD PD PR vs. SD PR vs. PD
WBC (× 109/l) 9.58 9.24 7.56 NS NS (p = 0.078)
post 1c. vs. 0 ↓ (p < 0.0001) ↓ (p = 0.001) NS
post 3c. vs. 0 ↓ (p < 0.0001) ↓ (p = 0.002) NS
neutrophils (× 109/l) 6.39 5.61 4.67 NS NS (p = 0.064)
post 1c. vs. 0 ↓ (p < 0.0001) ↓ (p < 0.0001) NS
post 3c. vs. 0 ↓ (p < 0.0001) ↓ (p < 0.0001) ↓ (p = 0.032*)
lymphocytes (× 109/l) 2.04 2.27 2.16 NS NS
post 1c. vs. 0 NS NS NS
post 3c. vs. 0 NS NS ↑ (p = 0.003)
monocytes (× 109/l) 0.97 0.87 0.65 NS
p = 0.021
post 1c. vs. 0 NS ↑ (p = 0.002) NS
post 3c. vs. 0 NS ↑ (p < 0.0001) NS
eosynocytes (× 109/l) 0.16 0.15 0.2 NS NS
post 1c. vs. 0 ↓ (p = 0.01) ↓ (p = 0.008) ↓ (p = 0.032*)
post 3c. vs. 0 ↓ (p = 0.0005) ↓ (p = 0.003) NS
basocytes (× 109/l) 0.05 0.04 0.05 NS NS
post 1c. vs. 0 NS NS ↓ NS (p = 0.07**)
post 3c. vs. 0 ↓ (p = 0.023*) NS NS
haemoglobin (g/dl) 13.15 13.9 13.1 NS NS
post 1c. vs. 0 ↓ (p = 0.001) ↓ (p < 0.0001) ↓ (p = 0.012)
post 3c. vs. 0 ↓ (p < 0.0001) ↓ (p < 0.0001) ↓ (p < 0.003)
PLT (× 109/l) 279.5 298 325.5 NS NS
post 1c. vs. 0 ↑ (p = 0.001) ↑ (p < 0.0001) NS
post 3c. vs. 0 NS NS NS
NLR 2.88 3.12 2.28 NS NS
post 1c. vs. 0 ↓ (p < 0.0001) ↓ (p < 0.0001) NS
post 3c. vs. 0 ↓ (p < 0.0001) ↓ (p < 0.0001) ↓ (p = 0.003)
LMR 1.94 2.69 3.09 NS NS
post 1c. vs. 0 NS ↓ (p < 0.0001) NS
post 3c. vs. 0 NS ↓ (p < 0.0001) NS
PLR 150.23 147.52 153.96 NS NS
post 1c. vs. 0 ↑ (p = 0.001) ↑ (p < 0.0001) NS
post 3c. vs. 0 ↑ (p = 0.024) NS ↓ (p = 0.003)
* without significant change of values in general Friedman test: only one value tends to be different to another (p: 0.05–0.1)
** without significant change of values in general Friedman test: only one value tends to be different to another (p ≥ 0.1)
0 – baseline; 1c. – first cycle of chemotherapy; 3c. – third cycle of chemotherapy; WBC – white blood cells; PLT – platelets; UA – uric acid; LDH – lactate dehydrogenase; NLR – neutrophil-to-lymphocyte ratio; LMR – lymphocyte-to-monocyte ratio; PLR – platelet-to-lymphocyte ratio; NS – non-significant; ↑ – increase; ↓ – decrease. COPD – chronic obstructive pulmonary disease; NS – not statistically significant
Discussion
Chronic obstructive pulmonary disease (COPD) is observed in about 50% of patients diagnosed with lung cancer [10, 11]. Airflow limitation is an indicator of greater risk of respiratory complications and cardiac arrhythmias that may potentially affect the process of diagnosis and treatment of lung cancer [12, 13]. An analysis of studies based on NSCLC patients following surgery revealed an association between the coexistence of both diseases and poorer prognosis [11, 14]. However, a prospective trial of 324 patients diagnosed with advanced NSCLC treated with systemic therapy revealed no significant differences in survival between the COPD and non-COPD groups [10]. Thus, the coexistence of COPD may adversely affect prognosis only in patients with early NSCLC, who are candidates for radical surgery. Our results are concordant with these observations.
Cigarette smoking generates about 6000 toxic compounds, carcinogens, radical solids, and oxidants [15]. Tobacco components affect the respiratory system by the generation of oxidative stress and promotion of inflammation. Consequently, these mechanisms induce epithelial cell damage or cell death with simultaneous activation of reactive damage repair and enhanced proliferation [16]. The dichotomous influence of smoking is a cause of COPD (cell death) and lung cancer proliferation. Cigarette smoking has also been found to have a negative impact on the response to anti-cancer therapy, both in vitro and in vivo [9]. However, no differences have been found in response to chemotherapy depending on current smoking status.
COPD is accompanied by chronic inflammation in the airways. This inflammation has a specific pattern with increased numbers of cytotoxic T lymphocytes and coexisting infiltration by neutrophils and macrophages that release inflammatory mediators and oxidants [17]. The conception of the protective role played by the immune system against cancer has already been documented [18]; however, the proposition by Virchow (1863) that cancer development and progression are connected with inflammation has yet to be disproved [3, 19].
A convincing body of evidence suggests that macrophages located in the tumour microenvironment (tumour-associated macrophages – TAM) can kill tumour cells or foster cancer promotion by the modulation of cytotoxic T-cell activity [20]. The presence of a higher number of monocytes, circulating blood precursors of macrophages, corresponds with poor prognosis and worse response to treatment in many malignancies [21–23]. Lin et al. note that AMC ≥ 0.45 × 109/l is a significant adverse prognostic factor in metastatic NSCLC (OS HR = 2.04) [24]. Our findings indicate no difference in AMC between the COPD and non-COPD groups, or between current smokers and ex-smokers. However, higher baseline AMC was found in patients with better response to chemotherapy than those with progression of cancer (p = 0.021).
The presence of a lower lymphocyte-to-monocyte ratio (LMR) was an adverse prognostic biomarker for resected NSCLC (OS HR = 1.51; DFS HR = 1.34) [25] and for other malignancies [26, 27]. In metastatic NSCLC, LMR ≥ 4.56 was found to correlate with better PFS (HR = 0.66) and OS (HR = 0.53) [24]. In our analysis, no differences in pretreatment LMR values were observed between groups, and LMR did not predict response to therapy.
Lymphocytes play a crucial role in the cell-mediated host immune response to tumours. Infiltration of tumours by lymphocytes (tumour-infiltrating lymphocytes – TILs) correlates with better prognosis in triple-negative breast cancer [28] or ovarian cancer [29]. Several trials investigating whether peripheral lymphocyte level can be used as a marker to predict the course of cancer found that higher levels are associated with a positive effect on outcome [30], and lower lymphocyte counts with a poor outcome [21]. Such results were obtained both in early-stage and advanced NSCLC [31, 32]. Higher baseline ALC was found in the absence of COPD, but no baseline difference was found between groups depending on response to treatment. Nevertheless, disease progression was associated with an increase of ALC during treatment.
Pretreatment absolute neutrophil count (ANC) is known to be an independent indicator of poor prognosis in lung cancer patients [31]. An analysis by Teramukai et al. found that in patients diagnosed with stage IIIB or IV NCSLC treated with chemotherapy, with a cut-off value of 4.5 × 109 neutrophils/l measured before treatment, low-neutrophil count was significantly associated with longer survival (median OS 19.3 for the low-neutrophil group vs. 10.2 months for the high-neutrophil group) [33]. Higher pretreatment ANC was found in current smokers than ex-smokers. Patients who had better response to chemotherapy tended to have higher baseline ANC than those who had progression (p = 0.06); however, a significant decline in ANC was observed only in those with disease control.
Many trials have evaluated the prognostic impact of NLR (defined as absolute neutrophil count divided by absolute lymphocyte count) as a surrogate marker of systemic inflammatory response in malignancy. Based on these results it has been proposed that NLR be assessed as an independent prognostic factor for survival, regardless of cancer localisation [34–36]. In non-small cell lung cancer patients treated with EGFR-TKIs (tyrosine kinase inhibitors), elevated NLR (≥ 3.5) was associated with lower objective response rate (52% vs. 79%), and shorter PFS (median 8.2 vs. 10.6 months; HR = 3.90) and OS (17.2 vs. 23.2 months; HR = 3.29) [37]. Among patients enrolled in the First-SIGNAL prospective study (non-smokers with adenocarcinoma treated with chemotherapy or EGFR-TKI), NLR was assessed at two points in time: at baseline and after one cycle of treatment. The study showed that significant reduction of NLR during treatment was associated with better tumour response (in the chemotherapy arm, median percentage changes of NLR in PR, SD, and PD subgroups were 50%, 41%, and 20%, respectively) and longer survival time (median OS 20.7 vs. 7.9 months) [38]. Another trial conducted in a typical population of patients with advanced NSCLC, with an NLR cut-off point of 2.63, documented that lower pretreatment NLR and its decline during chemotherapy correlated significantly with better response to chemotherapy [39]. Our analysis confirms the association between early NLR reduction and disease control: the change was observed in patients with PR and SD after the first cycle of chemotherapy, although a significant decrease was also observed after the third cycle in the PD population.
In a meta-analysis of trials, pretreatment platelet-to-lymphocyte ratio (PLR) was found to be an adverse prognostic factor in gastric cancer, colorectal cancer, ovarian cancer, and NSCLC [40]. In a prospective study of 210 patients with advanced NSCLC, the cut-off value for NRL at pretreatment was defined as 152.6. The study showed that elevated NLR was associated with poor response to first-line chemotherapy (OR = 4.50) and worse OS (HR = 2.03) [41]. Despite no differences in baseline PLR, our study showed early increase of PLR in the PR and SD groups. After the third cycle, PLR was higher than baseline in the PR group but lower in the PD population. COPD or smoking status did not affect PLR.
A major limitation of our study is that it is a retrospective study involving a relatively small number of patients. In addition, as the analysed variables could be influenced by other factors, it is important to validate the proposed predictive and prognostic factors and their correlation with COPD or smoking status in future prospective studies.
In conclusion, COPD and smoking induce chronic systemic inflammation and oxidative stress, which influence standard laboratory tests. Our findings indicate that these processes did not change the response rate of lung cancer to chemotherapy. A literature review reveals that some CBC parameters may act as potentially useful biomarkers of tumour response to chemotherapy and patient survival. However, as this is a retrospective study with a limited population size, further prospective studies are warranted.
The authors declare no conflict of interest.
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Contemp Oncol (Pozn)Contemp Oncol (Pozn)WOContemporary Oncology1428-25261897-4309Termedia Publishing House 2890810.5114/wo.2016.64607Original PaperQuality of life in chronic myeloid leukaemia patients after haematopoietic cell transplantation pretreated with second-generation tyrosine kinase inhibitors Piekarska Agnieszka 1Gil Lidia 2Jakitowicz Karolina 1Prejzner Witold 1Komarnicki Mieczysław 2Hellmann Andrzej 11 Department of Hematology and Transplantology, Medical University of Gdańsk, University Clinical Center, Gdansk, Poland2 Department of Haematology and Bone Marrow Transplantation, Poznan University of Medical Sciences, Poznan, PolandAddress for correspondence: Agnieszka Piekarska, Department of Hematology and Transplantology, Medical University of Gdańsk, University Clinical Center, Debinki 7, 80-952 Gdańsk, Poland. e-mail: babajaga@gumed.edu.pl20 12 2016 2016 20 5 414 417 21 5 2015 09 10 2015 Copyright: © 2016 Termedia Sp. z o. o.2016This is an Open Access article distributed under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International (CC BY-NC-SA 4.0) License, allowing third parties to copy and redistribute the material in any medium or format and to remix, transform, and build upon the material, provided the original work is properly cited and states its license.Aim of the study
The majority of patients with chronic myeloid leukaemia (CML) respond to tyrosine kinase inhibitors (TKI), while allogeneic haematopoietic cell transplantation (HCT) is indicated in selected clinical situations. HCT carries the risk of severe complications, while the toxicity profile of dasatinib and nilotinib may lead to adverse reactions affecting the quality of life (QoL). We present the results of observational analysis of CML patients who underwent HCT after exposure to second-generation TKI (TKI2), with respect to their quality of life assessed comparatively after transplantation.
Material and methods
Eligible subjects included 19 patients. The quality of life and global health assessment were performed with a questionnaire comparing the signs and symptoms present during the TKI2-therapy with those related to post-transplant complications, including psychosocial problems.
Results and conclusions
Most patients had no/few problems with exhausting activities, no/few difficulties during long-distance walks, and do not/rarely rest in the daytime. Seventeen (89.5%) patients reported at least one symptom related to TKI2-therapy and most of them disappeared after HCT. Thirteen (68.4%) patients noted no serious complication after HCT. Most patients claimed to have a very good QoL and general health compared to the period prior to HCT. We found statistically significant improvement in global health (p = 0.016) and QoL (p = 0.043) after HCT.
From the survivors perspective, HCT influence positively general health and QoL comparing to TKI2-therapy period. Further studies on larger group of patients will more precisely define the QoL level and possible predictors of changes in QoL, to assess which group of patients needs psychological support.
tyrosine kinase inhibitorsallogeneic hematopoietic cell transplantationquality of life
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Introduction
Prior to the era of tyrosine kinase inhibitors (TKI), allogeneic haematopoietic cell transplantation (HCT) was the standard curative therapy for patients with chronic phase (CP) chronic myeloid leukaemia (CML). For more than a decade, the majority of CML patients have responded to oral targeted therapy, while HCT is indicated in well-defined clinical situations: advanced phase at diagnosis (accelerated phase – AcP; blast phase/crisis – BP) or resistance to imatinib or second-generation TKI (TKI2), e.g. dasatinib, nilotinib [1]. An HCT procedure, giving the hope for long-lasting remission, carries the risk of even fatal complications, while the toxicity profile of both dasatinib and nilotinib may lead to various adverse reactions, affecting the quality of life (QoL) [2–4]. Moreover, prolonged therapy with TKI2 may influence post-transplant complications e.g. development of hepatic veno-occlusive disease (VOD), cardiac toxicity, immune dysfunctions, delayed engraftment, or graft versus host disease (GvHD). The long-term outcome of TKI2-resistant patients remains the issue of their concerns. Potential selection of more aggressive clones may increase the risk of post-HCT relapse and requirement for additional post-transplant therapy [5–8]. Other problems that patients face are caused by the late toxicity of HCT and GvHD-related complications, significantly affecting their quality of life [9].
In this study we present the results of observational analysis of CML patients who underwent HCT after exposure to TKI2, as the second-line therapy, with respect to their quality of life assessed comparatively after transplantation.
Material and methods
Patients
Eligible subjects were patients with CML, who underwent HCT after pre-treatment with imatinib mesylate and one or more TKI2 in two transplant centres, between February 2008 and November 2013. The therapy with TKI2 was discontinued at least two days prior to the conditioning regimen.
The study was approved by the Bioethical Committee of the Medical University of Gdansk and was conducted in accordance with the Declaration of Helsinki.
Definitions
Chronic, accelerated, and blast phases of CML were diagnosed according to ELN criteria [1]. Molecular monitoring was performed according to the ELN guidelines with the RQ-PCR method [10–12]. Deep molecular response MR4.5 was defined as a 4.5-log reduction from the baseline (≤ 0.0032% BCR-ABL [IS]) or a disease undetectable in cDNA with the amount of the transcript ABL ≥ 32.000. Deep MR4.0 was defined as a 4-log reduction from the baseline (≤ 0.01% BCR-ABL [IS]) or a disease that was undetectable in cDNA with the amount of the transcript ABL ≥ 10.000. Major molecular response (MMR) was determined when there was a 3-log reduction from the baseline (≤ 0.1% BCR-ABL [IS]).
Progression/relapse of CML after HCT was diagnosed with the hematologic, cytogenetic or molecular evidence of the disease that required any additional CML-related therapy after HCT (e.g. TKI re-administration and/or donor lymphocyte infusion [DLI]).
Acute graft versus host disease (GvHD) was diagnosed according to IBMTR criteria [13, 14]. The diagnosis of chronic GvHD was based on NIH consensus criteria [15].
Hepatic VOD was diagnosed with modified Seattle criteria [16].
Quality of life assessment
The quality of life and subjective global health assessment was performed with the use of a questionnaire based on the standard quality of life scale [17]. Patients were reviewed not earlier than 100 days after HCT. The questionnaire was composed to compare the signs and symptoms present during the TKI2 therapy with those related to post-transplant complications. Patients filled in the questionnaire during their routine control visits in the transplant out-patient.
The first five questions concentrated on everyday activities (carrying things, long and short walks, time spent in bed in daytime, help required in self-service). Patients could choose and sign on the scale one of four possible answers.
The next part was in the form of a table with listed complaints and side effects (e.g. short breath, pain, insomnia, fatigue, weakness, lack of appetite, nausea, vomiting, diarrhoea, worries and fear, sadness, and limits in the everyday and social life) experienced during the TKI2 therapy and subsequently (after HCT). The possible answers were “yes” or “no” for every complaint.
The last part was the patient’s estimation (in the form of a scale grading from 1 to 8) of their subjective global health and QoL during TKI2 therapy and subsequently.
Statistical analysis
Differences in mean values between group comparisons were analysed with the Mann-Whitney U test. Data obtained from the questionnaires were presented comparatively with the use of descriptive statistics. Differences in the assessment of global health and QoL were calculated with Pearson chi-square test. P-values < 0.05 were considered statistically significant. Calculations were performed using Stata 13.1 statistical software (StataCorp, TX, USA).
Results
We prospectively analysed the data of 19 patients treated with the second-generation TKI (dasatinib, nilotinib, or both in sequence) before HCT, who survived at least 100 days after transplantation. Their characteristics are presented in Table 1. The last update of collected data was done in February 2014.
Table 1 Patient characteristics
Sex, no. (%)
Male
Female
9 (48)
10 (52)
Median age at HCT (range) 51 (29–68)
Median age at QoL assessment (range) 53 (31–70)
Second-generation TKI (TKI2), no. (%)
Dasatinib
Nilotinib
Both
9 (48)
5 (26)
5 (26)
Disease phase at diagnosis, no. (%)
Chronic phase
Accelerated phase
Blast phase (crisis)
16 (85)
2 (10)
1 (5)
Disease phase at TKI2 treatment, no. (%)
Chronic phase
Accelerated phase
Blast phase (crisis)
16 (85)
2 (10)
1 (5)
Disease phase prior to HCT, no. (%)
Chronic phase (CP)
Accelerated phase or higher CP
Blast phase (crisis)
13 (68)
6 (32)
0 (0)
TKI2 therapy duration prior to HCT, no. (%)
Median (range)
> 12 months
≤ 12 months
18 (2–60)
12 (63)
7 (37)
Donor type, no. (%)
HLA-identical sibling
Matched unrelated
6 (32)
13 (68)
Conditioning regimen, no. (%)
MAC (BuCy; TBICy)
RIC (FluMel; FluBu; MelTreoFlu)
7 (37)
12 (63)
Graft type, no. (%)
PBSC
BM
16 (84)
3 (16)
HCT – haematopoietic cell transplantation; TKI2 – second-generation tyrosine kinase inhibitors; MAC – myeloablative conditioning; RIC – reduced-intensity conditioning; PBSC – peripheral blood stem cells; BM – bone marrow
Response to treatment and post-transplant complications
Seventeen patients achieved MR4.5 or MR4.0 at a median time of 1.8 months after HCT, and this response was maintained in 13 patients. Two patients achieved MMR, as the best molecular response, at a median time of 1.1 months after HCT. Relapse incidence after HCT in the reviewed group was 21%. Altogether, one haematological relapse and three molecular relapses were diagnosed. Three patients received DLI due to molecular relapses and one due to haematological relapse (combined treatment with DLI and dasatinib). All of them remain in deep MR until the time of writing.
Mild or moderate VOD was diagnosed in three (16%) patients from the analysed group, with complete recovery. Acute GvHD (grade 1–2) was observed in two (10%) patients. In all reviewed patients the timed elapsed from HCT and the presented symptoms enabled us to assess the chronic GvHD incidence and severity. It was diagnosed in nine (47%) cases, including one person with cGvHD promoted by DLI. Five patients were assessed as mild cGvHD and three patients as moderate cGvHD.
Quality of life
Assessment of current situation
Sixteen (84.2%) patients had no or few problems with exhausting everyday activities. Only three of them experience moderate problems. Fifteen (78.9%) patients have no or few difficulties during long-distance walks, while only four of them claimed to have moderate difficulties. Shorts walks caused no or just a few problems in all of the questioned subjects. Sixteen (84.2%) patients did not or rarely needed to rest in bed during the daytime. Three of them sometimes needed to rest in bed during the day. None of the questioned needed help when eating, dressing, washing, or using the toilet.
Assessment of TKI2 toxicity and HCT-related complications
Seventeen (89.5%) patients reported at least one symptom related to TKI2 therapy. Most of the symptoms present during TKI2 therapy disappeared after HCT including weakness, lack of appetite, nausea, vomiting, pain, worries, fear, and weakness.
Thirteen (68.4%) patients noted no serious complication after HCT. Two patients reported occurrence of diarrhoea (10.5%), one reported weakness (5.2%), and two reported a little pain (10.5%) and/or problems with sleeping (10.5%). Two patients experience some limits in everyday and social life at the time of writing.
Assessment of general health and QoL
Most patients claimed to have a very good QoL and general health compared to the time prior to HCT. The detailed results of the questionnaire are presented in Table 2 and Table 3. The differences in the assessment of global health (p = 0.016) and quality of life (p = 0.043) during TKI2 therapy and after HCT are both statistically significant. Moreover, 15 (78.9%) patients noted at least one grade improvement in their general health and QoL and only two (10.5%) patients reported one grade worsening in their global health and QoL after HCT.
Table 2 General health assessment
Score on the scale (1–8) During TKI2 therapy no. (%) After HCT no. (%)
1–2 score 0 (0) 0 (0)
3–4 score 6 (31.6) 1 (5.2)
5–6 score 11 (57.9) 9 (47.4)
7–8 score 2 (10.5) 9 (47.4)
Table 3 Quality of life assessment
Score on the scale (1–8) During TKI2 therapy no. (%) After HCT no. (%)
1–2 score 0 (0) 0 (0)
3–4 score 3 (15.9) 2 (10.5)
5–6 score 14 (73.7) 8 (42.1)
7–8 score 2 (10.5) 9 (47.4)
Discussion
Therapy with tyrosine kinase inhibitors has been a standard care for patients with CML for more than a decade. Since the majority of patients respond to the therapy and achieve long-lasting deep MR, the group of patients allotransplanted with CML diagnosis is currently limited. In our study we analysed the survivors of HCT procedure, with the follow-up long enough to assess the influence of the most important complications of HCT on QoL. Due to this “preselection”, the results concerning the incidence of hepatic VOD and GvHD should not be compared to the whole population of CML patients who undergo HCT. All these data are presented to create the clinical background for QoL analysis.
CML patients require continuous treatment, necessary to control the malignant disease but also related to many adverse reactions that were listed as possible complaints in the questionnaire. The most common adverse reactions of nilotinib include headache, weakness, skin changes, pruritus, nausea, vomiting, diarrhoea, symptoms secondary to cytopaenias (anaemia, thrombocytopaenia, neutropaenia), abnormalities in electrocardiography (ECG), increase of liver enzymes, and lipase in serum. A nilotinib daily dose ranges from 600 mg to 800 mg given twice daily on an empty stomach one hour before the meal or two hours after the meal. The list of most serious adverse reactions of dasatinib includes drug-related fluid retention (superficial oedema, pleural effusion), headache, weakness, skin changes, nausea, vomiting, diarrhoea, consequences of cytopaenia, and muscular and joint pain. A dasatinib daily dose ranges from 50 mg to 140 mg with no meal-associated scheduling. As dasatinib and nilotinib tablets contain lactose, patients with lactose intolerance may experience adverse symptoms from the GI tract. Patients are aware that they must tolerate all of the “inconveniences” of TKI2 therapy for many years, probably until the end of their life, and this fact can be frustrating for some of them. Furthermore, there is no guarantee of long-lasting remission, especially in the case of more advanced phase of the disease at diagnosis.
The patients reviewed in our study faced and survived a life-threatening procedure of allogeneic haematopoietic cell transplantation that must have had a certain impact on their physical and psychological condition. After HCT, they also experience the fear of a possible relapse and consequences of HCT-related complications, e.g. acute and chronic GvHD or recurrent infections. On the other hand, they know that immunosuppressive and anti-infectious therapy is used temporally and most patients do not require any treatment one year after HCT. The limited time of post-transplant treatment increases the patients’ sense of “being healthy” or even cured from leukaemia. That is why the questionnaire was created to assess the current physical condition, and then it enabled a comparison with certain problems before HCT (during TKI2 therapy) and after HCT (subsequently). The results of the study showed that HCT procedure, from the survivors’ perspective, positively influenced not only their general health, but also their evaluation of QoL.
We conclude that, in the view of the curative potential of HCT procedure and non-inferior QoL, HCT is the optimal option for CML patients with defined indications. In contrast to adverse reactions of TKI2-therapy, transplant-related complications are usually not permanent, and, therefore, acceptable for the patients. The presented results show some directions in the level of QoL but, nonetheless, further observation of more numerous samples is required to assess the individual influence of nilotinib and dasatinib on the transplant-related toxicity, HCT outcome, and QoL. Moreover, studies on larger groups of patients will more precisely define the level of QoL, as well as possible predictors of changes in QoL, to identify those who need psychological support.
The authors declare no conflict of interest.
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