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In this study, we investigated the performance of multiple enhanced NEWS2 models in terms of discrimination and calibration in predicting the risk of COVID-19. Model M0' uses NEWS2 alone; Model M1' extends M0' with age and sex and Model M2' extends M1' with all the subcomponents of NEWS2 plus diastolic blood pressure. Equivalent models (M0, M1, M2) using NEWS were also developed but model M2 excluded two parameters that are in NEWS2 but not in NEWS -oxygen flow rate and scale 2 (yes/no). |
NEWS2 models (M0', M1', M2') were more sensitive but less specific than NEWS models (M0, M1, M2). Models M2 and M2' were the best in class, with the highest c-statistics (0.77 and 0.72 respectively). The high negative predictive value suggests models M2 and M2' may be particularly useful in ruling out COVID-19 early in the patients unplanned admission which is clinically useful because testing for COVID-19 using viral nucleic acid testing is more time consuming than measuring and recording the patients vital signs data sets as defined by NEWS/NEWS2. A recent systematic review identified five models to detect COVID-19 infection in symptomatic individuals with c-statistics that ranged from 0.87 to 1 [21] . However, despite these high c-statistics, the review authors cautioned against the use of these models in clinical practice because of the high risk of bias and poor reporting of studies which are likely to have led to optimistic results [21] . For example, the majority of studies are with smaller sample size; the lack of external validation and calibration was rarely assessed [21] . Our study addresses these shortcomings. While most of the studies reported an insufficient sample size [21] , our study was sufficiently large for developing and validating the models in predicting the risk of COVID-19 [18] . The models were developed using data from one and validated using data from another hospital. We rigorously assessed the internal calibration using bootstrapping approach [22] . Furthermore, calibration slope and calibration-in-the-large are assessed and corrected. |
The main advantages of our NEWS/NEWS2 models are that they are designed to incorporate data that are already available in the patient's electronic health record and so place no additional data collection or computational burden on clinicians and can also be readily automated. Nonetheless, we emphasize that our NEWS/ NEWS2 models are not designed to replace clinical judgement. They are intended and designed to support, not subvert, the clinical decision-making process and can be always overridden by clinical concern [5, 23] . The working hypothesis for our models is that their use may enhance situational awareness of COVID-19 by processing information already available without impeding the workflow of clinical staff, especially as our approach offers a faster and less expensive assessment of COVID-19 There are limitations in relation to our study. We identified COVID-19 based on ICD-10 code 'U071' which was determined by clinical judgment and/or swab test results and so our findings are constrained by the accuracy of these methods [24, 25] . Moreover, we do not have the timing of diagnosis in our data and so we are unable to determine if patients arrived with COVID-19. Our two hospitals are part of the same NHS Trust and this may undermine the generalisability of our findings, and so further external validation may be worthwhile. Another issue related to generalisability is to determine the extent to which mass vaccinations for COVID-19 impact on the accuracy of our models. Finally, an important next phase of this work is to field-test our models by carefully engineering them into routine clinical practice [26, 27] to see if they do support the earlier detection and care of COVID-19 in emergency medical patients without unintended adverse consequences. |
NEWS model M2 and NEWS2 model M2' appear to provide reasonably accurate predictions of the risk of COVID-19 using routinely collected on-admission NEWS/NEWS2 datasets. The extent to which these models are clinically useful as an early warning system for COVID-19 at the time of admission should be studied. |
The online version contains supplementary material available at https://doi. org/10.1186/s12913-021-06951-x. |
Additional file 1: Table S1 . NEWS scoring chart. Table S2 . NEWS2 scoring chart. Table S3 . Number of emergency medical admissions included/excluded. Figure S1 . Escalation policy of deteriorating patients in York Teaching Hospital NHS Foundation Trust. Figure S2 . Boxplot for continuous covariates without outliers to COVID-19 (Yes/No) for development dataset. Figure S3 . Scatter plots showing the observed risk of COVID-19 with continuous covariates for the development dataset. Figure S4 . Boxplot for continuous covariates without outliers to COVID-19 (Yes/No) for validation dataset. Figure S5 . Scatter plots showing the observed risk of COVID-19 with continuous covariates for validation dataset. Figure S6 . Internal calibration of NEWS models (M0, M1, M2) and NEWS2 models (M0',M1',M2') for predicting the risk of COVID-19 in the development dataset. Table S4 . Performance of NEWS models (M0, M1, M2) and NEWS2 models (M0',M1',M2') for predicting the risk of COVID on admission for development dataset. Table S5 . Likelihood ratio tests for comparing NEWS models (M0, M1, M2) and NEWS2 models (M0',M1',M2') for predicting the risk of COVID on admission for development dataset. |
The Novel corona virus disease (COVID-19) pandemic, which was first reported in Wuhan, China, continues to affect millions of people across 216 countries and territories, with Mumbai metropolitan region emerging as one of the worst affected cities in the world and contributing to nearly half a million cases. 1, 2 The primarily modes of transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) appears to be through droplet, contact, fomite and airborne transmission. 3 Regions have been placed under various forms of lockdown, with restriction in movement of people, in an attempt to contain the spread of the disease. Neurosurgery centres form a unique subset, that must cater to unavoidable neurological emergencies like tumours, strokes, infections, and trauma. The pattern and volume of cases in neurosurgery centres across the world have changed significantly in the present scenario, leading to difficulties in resource planning and logistic management. [4] [5] [6] To prevent COVID-19 spread, various neurosurgical societies and institutions have published broad guidelines and recommendations, mostly based on third party data. [7] [8] [9] [10] [11] These protocols remain to be validated and surgical outcomes need to be analysed. The aim of this study is to validate the COVID-19 protocols of our neurosurgery centre and investigate the surgical outcomes. Another objective is to analyse the change in the disease pattern and neurosurgical volume, thereby establishing a benchmark for COVID-19 resource planning. |
This study was carried out at a tertiary care COVID-19 hospital, located in the Mumbai metropolitan region, one of world's largest COVID-19 hotspots. All patients who were admitted to the Neurosurgery department of the hospital for a major procedure, in the lockdown period between 15 March 2020 and 15 September 2020, were included in the study. Out-patient procedures, diagnostic procedures and minor surgeries were excluded from the study. As part of this study; surgery outcomes, disease pattern, anaesthesia techniques, patient demographics and COVID-19 status were analysed. Outcomes were measured using modified Rankin scale (mRS). They were compared with similar data, obtained |
All patients were triaged in priorities based on need for urgency of intervention (Table 1 ) |
All patients were also stratified based on COVID-19 status into three categories i.e. COVID-19 positive, indeterminate and negative; and were managed in respective dedicated zones as per hospital protocol. |
COVID-19 reverse transcription polymerase chain reaction test (COVID-19 RT-PCR) of nasopharyngeal and oropharyngeal swabs were performed in all patients requiring neurosurgery. In Priority I cases requiring immediate intervention, surgery was performed with full COVID-19 precautions and personal protection equipment (PPE), without waiting for results of COVID-19 RT-PCR; and following surgery, they were managed in a designated COVID-19 suspect ICU till the availability of the COVID-19 report. In Priority I cases, who could wait for a few hours before surgical intervention, faster diagnostic tests like Chip-based Real Time PCR Test (TrueNat SARS CoV-2), cartridge-based nucleic acid amplification test (GeneXpert Xpert Xpress SARS-CoV-2) or A dedicated operation theatre (OT), with isolated donning and doffing areas, having separate entry and exit, was employed for confirmed or suspected COVID-19 cases. Minimal staffing was maintained during surgery. In the absence of negative pressure OT in our institute, we designated a separate OT with two split air-conditioners of 2 tons of refrigeration capacity each, for conducting positive and suspected cases. All operation theatre personnel followed strict personal-protection measures including PPE consisting of waterproof hooded surgical gowns, N95 mask, shoe cover and face shield-visor ( Fig. 1 ). |
In a bid to minimise aerosol generating procedures (AGPs), general anaesthesia (GA) and ventilation was avoided as far possible during the perioperative period. If unavoidable, intubation was performed by the most experienced anaesthesiologist in the OT with the aid of a video laryngoscope. The plexiglass aerosol prevention box was used during all tracheal intubations, thus minimizing exposure of the OT personnel to aerosolized virus. With the sole aim to minimize aerosol spread in the OT; high-flow oxygen, nasal instrumentation, coughing, and bag and mask ventilation were avoided. Monitored anaesthesia care (MAC), which included regional anaesthesia, spinal anaesthesia and scalp block, was preferred to general anaesthesia, wherever possible. |
All disposable items such as surgical drapes, breathing circuit, heat and moisture exchanger (HME) with viral filter, gas sampling line, reservoir bag, face mask, tracheal tubes, airways and soda lime were discarded after every surgery as per biomedical waste management protocols. All exposed surfaces such as anaesthesia workstation, patient monitors, cabinets and laptops were covered with disposable plastic sheets. The sheets were disposed at the end of surgery, and the surfaces were cleaned with disinfectant solution (1% sodium hypochlorite). |
The strategy was to resect most of the tumours using awake craniotomy techniques and perform lumbar spine surgeries under spinal anaesthesia. During cranial surgery, the patient was placed in a barrier tent, exposing only the part to be operated (Fig. 1) . Monitoring of the surgical field was undertaken by J o u r n a l P r e -p r o o f incorporating a slave monitor. The neurosurgical team functioned as a compact and cohesive close-knit unit. |
Craniotomy placement was planned to avoid paranasal sinuses. In cases of paranasal sinus breach, immediate containment was done using bonewax. An attempt was made to avoid surgical AGP such as bone drilling, cavitron ultrasonic surgical aspiration (CUSA) and monopolar cauterisation. When their use was unavoidable, liberal irrigation and high-power suction were held close to the surgical field. |
The statistical analysis was done using a statistical package (IBM SPSS software V 25). The continuous variables (which were normally distributed) were summarised using mean and standard deviation and compared using t test. The categorical variables were summarised using contingency table and compared using chi square test. 95% confidence interval was used to assess the precision of sample estimates and alpha error was set to 0.05 for analyses. |
A total of 67 patients were admitted for neurosurgical procedures during this period. Eleven cases were found to have COVID-19. Surgery was deferred in five cases who were COVID-19 positive and hence excluded from the study. |
Brain tumor was the commonest diagnosis (25.80%) followed in incidence by spinal diseases (20.97 %). Stroke constituted 12.90% of total cases ( Table 2 ). |
Out of the 62 patients who were operated, 4 were diagnosed to have COVID-19 before surgery. In 13 instances, the COVID-19 testing was not done prior to surgery due to emergent nature of cases. These cases were empirically labelled as COVID-19 indeterminate and surgery was performed with adequate COVID precautions and PPE. Of these 13 patients who were taken up for emergency surgery, an immediate post-operative RT PCR turned out to be positive in 2 cases. |
The overall case load of surgeries in the study period in 2020 was only 42.75% of that in 2019 and it reflected a statistically decrease in the overall workload (P < 0.001) ( Table 2 ). There was a significant increase in surgery for stroke (P = 0.008) and hydrocephalus (P <0.001) in 2020 when compared to 2019. Most of the decrease in workload in 2020 could be attributed to a significant reduction in elective spine surgeries (P < 0.001). However, there was no significant difference in emergency and essential (P1 and P2) caseloads between 2019 and 2020 (P = 0.482) ( Table 3 ). The patients of 2019 and 2020 groups were comparable with respect to age (P = 0.291) and sex (P = 0.079). |
There was a statistically significant increase in MAC techniques among emergency and essential surgeries in the study period 2020 when compared to 2019 (P < 0.001). There was no significant difference in overall outcomes in cases during the COVID-19 and non-COVID period (P = 0.237). |
Though there were 3 deaths among the GA patients, there was no significant difference in outcomes in patients subjected to general anaesthesia and MAC in 2020 (P = 0.250) ( Table 4 ). However, patients who had COVID-19 disease had poorer outcomes when compared to those who were COVID free (P = 0.003). Further there was a significant increase in mortality among COVID-19 patients subjected to GA when compared to MAC (p = 0.014). |
None of the Neurosurgery OT personnel showed symptoms of COVID-19 and they tested negative on serological survey using ELISA IgG and IgM tests and COVID-19 RT-PCR. |
Coronavirus disease (COVID-19) , caused by SARS-COV2, is primarily a respiratory disease that affects a myriad of organs and body systems including the nervous system. 13 Being a dedicated service hospital, our clientele consists of serving armed forces personnel and their dependants, as well as veterans. However as per the government directive, the hospital services were extended to the entire community during the ongoing pandemic. Stringent protocols were ensured in the prioritisation, segregation, and management of patients. These protocols were initially derived from guidelines of reputed organisations and societies, which we adapted to suit our requirements and subsequently modified based on our experience. 9, 10, 15, 17, [19] [20] [21] [22] The Neurosurgical operation suite is a potential high-risk environment for the transmission of SARS-CoV-2 virus due to the requirement of undertaking aerosol generating procedures like endotracheal intubation, mechanical ventilation, high-speed drilling, ultrasonic aspiration and cauterisation. Further the risk is enhanced by the proximity of oral and nasal orifices to the operative field and long duration of surgery in a contained environment. Certain neurosurgical approaches like trans-nasal trans-J o u r n a l P r e -p r o o f sphenoidal route for pituitary tumours, retro-mastoid surgery for cerebellopontine tumours and supraorbital corridors for skull base pathologies are inherently more hazardous as they involve breech of para nasal sinuses. [23] [24] [25] [26] The risk is enhanced by the requirement of discarding some components of personal protective equipment like face shield while using operating microscope and fibreoptic bronchoscope. In our study, none of the Neurosurgery OT personnel contracted COVID-19, as confirmed by RT PCR and sero-surveillance with ELISA IgG and IgM, thereby validating the efficacy of our protocols. However, two personnel employed in the Neurosurgical ward (a paramedical staff and a sanitation worker) tested positive for SARS-CoV-2. |
There seems to be an absence of consensus regarding the safer type of anaesthesia for COVID-19 patients. Some guidelines recommend regional and monitored anaesthesia care (MAC) whereas others advocate general anaesthesia. 21, 22 Proponents of general anaesthesia argue that intraoperative coughing during regional anaesthesia may lead to aerosol generation and brain bulge. 22 However, we found that MAC techniques like awake craniotomy, regional anaesthesia and field blocks were safe, both to patients and the neurosurgical team in the current scenario. Because of the possibility of respiratory trauma caused by increased lung pressures during ventilation, a voluntary effort was made to perform the cases without ventilator [Neto] . 27 virus to the brain included involvement of the olfactory bulb through the cribriform plate leading to further dissemination, and blood borne spread of virus leading to involvement of glial cells , neurons and cerebral capillary endothelium through ACE2 receptor pathway, indicating probable neurotropism. 14, 29 Indirect mechanisms of brain injury include secondary damage due to hypoxia, coagulopathy and immune-meditated neurologic injury. 14,29 Frequent neurological symptoms include anosmia, altered sensorium, headache and giddiness. 14,30 Some authors have reported an increased incidence of intracerebral hemorrhage, ischemic stroke, and cerebral venous thrombosis in patients suffering from COVID-19. 14, 29, 31 Rare cases of acute necrotizing encephalopathy, meningitis and encephalitis have also been documents in these patients. 14, 29, 31 In a study by Doglietto et al, post-operative mortality, pulmonary complications and thrombotic events were significantly higher in those with COVID-19 compared with control patients. 32 In our protocol, as antibody testing for SARS-CoV-2 virus was not included, we were not aware if the patient had suffered from COVID-19 in the recent past. Though RT PCR remains the gold standard for diagnosis, it has a substantial false negative rate especially in the early phase of the disease. 33 Hence the exact incidence of patients who had suffered from COVID-19 in the past or those in the early stage of the disease, remains speculative in our study. In our study there was no significant difference in surgical outcomes when compared to a matched control of patients in a similar time frame in the previous year. |
However, there was a statistically significant incidence of morbidity and mortality in the subgroup patients who were positive for COVID -19 (p=0.003). |
Many neurosurgery centres have reported significant decrease in the number of cases undergoing surgery. [4] [5] [6] [34] [35] [36] Appropriate resource allocation remains a challenge due to non-availability of data regarding the volume and patterns of disease among neurosurgery patients on one hand, and shortage of funds, as these have been diverted to manage this pandemic, on the other. 20, 37, 38 In our centre, there was about 57% decrease in the total number of cases during this lockdown when compared to a similar J o u r n a l P r e -p r o o f timeframe in the previous year. However, there was no statistical decrease in the number of priority 1 and 2 cases. Cranial cases, especially brain tumours and strokes, accounted for majority of cases (79.03 %). Much of the reduction in workload was due to lesser number of elective spine surgeries. We attempt to set a guideline to aid centres in planning neurosurgical resource management, equipment and logistic requirements. Neurosurgery centres must accordingly orient their resources and funds towards these essential procedures, as the load of these surgeries have not decreased significantly. |
There was a significant decrease in neurosurgical workload in the COVID-19 lockdown period in 2020, however the volume of emergency and essential surgeries remained the same as compared to the previous year. Hence resources must be appropriated accordingly to cater to these emergencies. Surgery in COVID-19 patients should be postponed, unless critical, as the outcomes in these patients are worse. |
Monitored anaesthesia care techniques like awake craniotomy, regional and spinal anaesthesia should be employed, wherever possible, to attain a better outcome in the COVID-19 era. J o u r n a l P r e -p r o o f |