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Surgery_Schwartz_14002

Surgery_Schwartz

patients with atrial fibrillation results in small stroke reduction but increased bleeding risk and substantial inconvenienceUncertainty or variability in values and preferencesYoung patients with lymphoma will invariably place a highervalue on the life prolonging effects of chemotherapy than on treatment toxicityOlder patients with lymphoma may not place a higher value on the life prolonging effects of chemotherapy than on treatment toxicityUncertainty about whether the intervention represents a wise use of resourcesThe low cost of aspirin as prophylaxis against stroke in patients with transient ischemic attacksThe high cost of clopidogrel and of combination dipyridamole and aspirin as prophylaxis against stroke in patients with transient ischaemic attacks1. An explicit description of development and funding pro-cesses that is publicly available.2. A transparent process that minimizes bias, distortion, and conflicts of interest.3. Developed by a multidisciplinary panel composed of:

Surgery_Schwartz. patients with atrial fibrillation results in small stroke reduction but increased bleeding risk and substantial inconvenienceUncertainty or variability in values and preferencesYoung patients with lymphoma will invariably place a highervalue on the life prolonging effects of chemotherapy than on treatment toxicityOlder patients with lymphoma may not place a higher value on the life prolonging effects of chemotherapy than on treatment toxicityUncertainty about whether the intervention represents a wise use of resourcesThe low cost of aspirin as prophylaxis against stroke in patients with transient ischemic attacksThe high cost of clopidogrel and of combination dipyridamole and aspirin as prophylaxis against stroke in patients with transient ischaemic attacks1. An explicit description of development and funding pro-cesses that is publicly available.2. A transparent process that minimizes bias, distortion, and conflicts of interest.3. Developed by a multidisciplinary panel composed of:

Surgery_Schwartz_14003

Surgery_Schwartz

and funding pro-cesses that is publicly available.2. A transparent process that minimizes bias, distortion, and conflicts of interest.3. Developed by a multidisciplinary panel composed of: clini-cians, methodological experts, and representatives, includ-ing a patient or consumer, of populations expected to be affected by the guideline.4. Utilizes rigorous systematic evidence review and considers quality, quantity, and consistency of the aggregate of avail-able evidence.5. Summarizes evidence about potential benefits and harms relevant to each recommendation.6. Explains the parts that values, opinion, theory, and clinical experience play in deriving recommendations.7. Provides a rating of the level of confidence in the evidence underpinning each recommendation and a rating of the strength of each recommendation.8. Undergoes extensive external review that includes an open period for public comment.9. Has a mechanism for revision when new evidence becomes available.Depending upon the

Surgery_Schwartz. and funding pro-cesses that is publicly available.2. A transparent process that minimizes bias, distortion, and conflicts of interest.3. Developed by a multidisciplinary panel composed of: clini-cians, methodological experts, and representatives, includ-ing a patient or consumer, of populations expected to be affected by the guideline.4. Utilizes rigorous systematic evidence review and considers quality, quantity, and consistency of the aggregate of avail-able evidence.5. Summarizes evidence about potential benefits and harms relevant to each recommendation.6. Explains the parts that values, opinion, theory, and clinical experience play in deriving recommendations.7. Provides a rating of the level of confidence in the evidence underpinning each recommendation and a rating of the strength of each recommendation.8. Undergoes extensive external review that includes an open period for public comment.9. Has a mechanism for revision when new evidence becomes available.Depending upon the

Surgery_Schwartz_14004

Surgery_Schwartz

of each recommendation.8. Undergoes extensive external review that includes an open period for public comment.9. Has a mechanism for revision when new evidence becomes available.Depending upon the clinical question, such guidelines are often interpreted as the standard of care. However, multiple clinical guidelines may be applicable with respect to various aspects of a given clinical situation and must not be followed blindly without considering specific situational issues through the lens of an experienced clinician. Moreover, guidelines do not (and probably cannot) exist for all clinical situations. Clini-cians often must resort to other resources to enrich the context in which decisions are made, and, as with all evidence, care must be taken not to extrapolate the application of a clinical guideline beyond its specific conditions.THE CHALLENGES OF APPLYING EBM TO SURGERYAs noted earlier, the application of EBM to surgery has lagged behind other fields of medicine, and this has been

Surgery_Schwartz. of each recommendation.8. Undergoes extensive external review that includes an open period for public comment.9. Has a mechanism for revision when new evidence becomes available.Depending upon the clinical question, such guidelines are often interpreted as the standard of care. However, multiple clinical guidelines may be applicable with respect to various aspects of a given clinical situation and must not be followed blindly without considering specific situational issues through the lens of an experienced clinician. Moreover, guidelines do not (and probably cannot) exist for all clinical situations. Clini-cians often must resort to other resources to enrich the context in which decisions are made, and, as with all evidence, care must be taken not to extrapolate the application of a clinical guideline beyond its specific conditions.THE CHALLENGES OF APPLYING EBM TO SURGERYAs noted earlier, the application of EBM to surgery has lagged behind other fields of medicine, and this has been

Surgery_Schwartz_14005

Surgery_Schwartz

guideline beyond its specific conditions.THE CHALLENGES OF APPLYING EBM TO SURGERYAs noted earlier, the application of EBM to surgery has lagged behind other fields of medicine, and this has been attributed to the difficulty in establishing a sufficient mass of evidence with the “gold standard” RCT. Here we describe the process of evaluating the quality of a RCT and note the challenges related to the execution of a high-quality RCT in a surgical context.Analysis of a Surgical Randomized Control TrialSufficient knowledge of the trial’s methodological accuracy and results are essential for critical appraisal. However, less than half of journal articles adequately report the study design.19 This deficiency led to the development of the Consoli-dated Standards of Reporting Trials (CONSORT) guidelines in 1992, which was subsequently revised in 2010.20 These guide-lines are a minimal set of recommendations for reporting RCTs (blinding, randomization, etc) to facilitate critical appraisal.

Surgery_Schwartz. guideline beyond its specific conditions.THE CHALLENGES OF APPLYING EBM TO SURGERYAs noted earlier, the application of EBM to surgery has lagged behind other fields of medicine, and this has been attributed to the difficulty in establishing a sufficient mass of evidence with the “gold standard” RCT. Here we describe the process of evaluating the quality of a RCT and note the challenges related to the execution of a high-quality RCT in a surgical context.Analysis of a Surgical Randomized Control TrialSufficient knowledge of the trial’s methodological accuracy and results are essential for critical appraisal. However, less than half of journal articles adequately report the study design.19 This deficiency led to the development of the Consoli-dated Standards of Reporting Trials (CONSORT) guidelines in 1992, which was subsequently revised in 2010.20 These guide-lines are a minimal set of recommendations for reporting RCTs (blinding, randomization, etc) to facilitate critical appraisal.

Surgery_Schwartz_14006

Surgery_Schwartz

in 1992, which was subsequently revised in 2010.20 These guide-lines are a minimal set of recommendations for reporting RCTs (blinding, randomization, etc) to facilitate critical appraisal. Many of the surgical journals now require completion of a CONSORT checklist prior to submission of the RCT manu-script (Fig. 51-3). Establishing this requirement has standard-ized the way articles are presented and analyzed. The two key aspects to focus on when assessing a RCT are internal and external validity.Internal ValidityDetermining the degree that the results of the RCT are accurate and consistent for the sample patients is called internal validity. Without internal validity, a study cannot be properly appraised, as the study was not constructed properly to answer the hypoth-esis without avoiding bias or confounding factors.21 The internal validity of a RCT requires the evaluation of several properties: randomization, blinding, equivalence among groups, complete-ness of follow-up, and

Surgery_Schwartz. in 1992, which was subsequently revised in 2010.20 These guide-lines are a minimal set of recommendations for reporting RCTs (blinding, randomization, etc) to facilitate critical appraisal. Many of the surgical journals now require completion of a CONSORT checklist prior to submission of the RCT manu-script (Fig. 51-3). Establishing this requirement has standard-ized the way articles are presented and analyzed. The two key aspects to focus on when assessing a RCT are internal and external validity.Internal ValidityDetermining the degree that the results of the RCT are accurate and consistent for the sample patients is called internal validity. Without internal validity, a study cannot be properly appraised, as the study was not constructed properly to answer the hypoth-esis without avoiding bias or confounding factors.21 The internal validity of a RCT requires the evaluation of several properties: randomization, blinding, equivalence among groups, complete-ness of follow-up, and

Surgery_Schwartz_14007

Surgery_Schwartz

bias or confounding factors.21 The internal validity of a RCT requires the evaluation of several properties: randomization, blinding, equivalence among groups, complete-ness of follow-up, and accuracy of analysis. These properties are discussed in the following section.Randomization. Randomization is the creation of participant groups with similar known and unknown prognostic factors to achieve the goal of eliminating selection bias. For example, if the investigator can decide which treatment the patient receives, he or she may assign a participant to a study arm that is more favorable for that specific patient. On outcomes analysis, certain groups may have an overestimated treatment effect due to patient selec-tion and not necessarily the intervention itself. The methodology 5Brunicardi_Ch51_p2137-p2152.indd 214428/02/19 4:19 PM 2145UNDERSTANDING, EVALUATING, AND USING EVIDENCE FOR SURGICAL PRACTICECHAPTER 51SectionItem NoChecklist itemTitle and Abstract1aIdentification as a

Surgery_Schwartz. bias or confounding factors.21 The internal validity of a RCT requires the evaluation of several properties: randomization, blinding, equivalence among groups, complete-ness of follow-up, and accuracy of analysis. These properties are discussed in the following section.Randomization. Randomization is the creation of participant groups with similar known and unknown prognostic factors to achieve the goal of eliminating selection bias. For example, if the investigator can decide which treatment the patient receives, he or she may assign a participant to a study arm that is more favorable for that specific patient. On outcomes analysis, certain groups may have an overestimated treatment effect due to patient selec-tion and not necessarily the intervention itself. The methodology 5Brunicardi_Ch51_p2137-p2152.indd 214428/02/19 4:19 PM 2145UNDERSTANDING, EVALUATING, AND USING EVIDENCE FOR SURGICAL PRACTICECHAPTER 51SectionItem NoChecklist itemTitle and Abstract1aIdentification as a

Surgery_Schwartz_14008

Surgery_Schwartz

214428/02/19 4:19 PM 2145UNDERSTANDING, EVALUATING, AND USING EVIDENCE FOR SURGICAL PRACTICECHAPTER 51SectionItem NoChecklist itemTitle and Abstract1aIdentification as a randomized trial in the title1bStructured summary of trial design, methods, results, and conclusionsBackground and Objectives2aScientific background and explanation of rationale2bSpecific objectives or hypothesesTrial Design3aDescription of trial design (such as parallel, factorial) including allocation ratio3bImportant changes to methods after trial commencement with reasonsParticipants4aEligibility criteria for participants4bSettings and locations where the data were collectedInterventions5The interventions for each group with sufficient details to allow replication, including how and when they were administeredOutcomes6aCompletely defined pre-specified primary and secondary outcome measures, including how and when they were assessed6bAny changes to trial outcomes after the trial commenced, with reasonsSample

Surgery_Schwartz. 214428/02/19 4:19 PM 2145UNDERSTANDING, EVALUATING, AND USING EVIDENCE FOR SURGICAL PRACTICECHAPTER 51SectionItem NoChecklist itemTitle and Abstract1aIdentification as a randomized trial in the title1bStructured summary of trial design, methods, results, and conclusionsBackground and Objectives2aScientific background and explanation of rationale2bSpecific objectives or hypothesesTrial Design3aDescription of trial design (such as parallel, factorial) including allocation ratio3bImportant changes to methods after trial commencement with reasonsParticipants4aEligibility criteria for participants4bSettings and locations where the data were collectedInterventions5The interventions for each group with sufficient details to allow replication, including how and when they were administeredOutcomes6aCompletely defined pre-specified primary and secondary outcome measures, including how and when they were assessed6bAny changes to trial outcomes after the trial commenced, with reasonsSample

Surgery_Schwartz_14009

Surgery_Schwartz

defined pre-specified primary and secondary outcome measures, including how and when they were assessed6bAny changes to trial outcomes after the trial commenced, with reasonsSample size7aHow sample size was determined7bWhen applicable, explanation of any interim analyses and stopping guidelinesRandomization: Sequence Generation8aMethod used to generate the random allocation sequence8bType of randomization; details of any restriction (such as blocking and block size)Allocation concealment mechanism9Mechanism used to implement the random allocation sequenceImplementation10Who generated the random allocation sequence, who enrolled participants, and who assigned interventionsBlinding11aIf done, who was blinded after assignment to interventions and how11bIf relevant, description of the similarity of interventionsResults Participant flow13aFor each group, the numbers of participants who were randomly assigned, received intended treatment, and were analyzed for the primary outcome13bFor each

Surgery_Schwartz. defined pre-specified primary and secondary outcome measures, including how and when they were assessed6bAny changes to trial outcomes after the trial commenced, with reasonsSample size7aHow sample size was determined7bWhen applicable, explanation of any interim analyses and stopping guidelinesRandomization: Sequence Generation8aMethod used to generate the random allocation sequence8bType of randomization; details of any restriction (such as blocking and block size)Allocation concealment mechanism9Mechanism used to implement the random allocation sequenceImplementation10Who generated the random allocation sequence, who enrolled participants, and who assigned interventionsBlinding11aIf done, who was blinded after assignment to interventions and how11bIf relevant, description of the similarity of interventionsResults Participant flow13aFor each group, the numbers of participants who were randomly assigned, received intended treatment, and were analyzed for the primary outcome13bFor each

Surgery_Schwartz_14010

Surgery_Schwartz

of interventionsResults Participant flow13aFor each group, the numbers of participants who were randomly assigned, received intended treatment, and were analyzed for the primary outcome13bFor each group, losses and exclusions after randomization, together with reasonsRecruitment14aDates defining the periods of recruitment and follow-up14bWhy the trial ended or was stoppedBaseline data15A table showing baseline demographic and clinical characteristics for each groupNumbers analyzed16For each group, number of participants (denominator) included in each analysis and whether the analysis was by original assigned groupsOutcomes and estimation17aFor each primary and secondary outcome, results for each group, and the estimated effect size and its precision (such as 95% confidence interval)17bFor binary outcomes, presentation of both absolute and relative effect sizes is recommendedAncillary analyses18Results of any other analyses performed, including subgroup analyses and adjusted analyses,

Surgery_Schwartz. of interventionsResults Participant flow13aFor each group, the numbers of participants who were randomly assigned, received intended treatment, and were analyzed for the primary outcome13bFor each group, losses and exclusions after randomization, together with reasonsRecruitment14aDates defining the periods of recruitment and follow-up14bWhy the trial ended or was stoppedBaseline data15A table showing baseline demographic and clinical characteristics for each groupNumbers analyzed16For each group, number of participants (denominator) included in each analysis and whether the analysis was by original assigned groupsOutcomes and estimation17aFor each primary and secondary outcome, results for each group, and the estimated effect size and its precision (such as 95% confidence interval)17bFor binary outcomes, presentation of both absolute and relative effect sizes is recommendedAncillary analyses18Results of any other analyses performed, including subgroup analyses and adjusted analyses,

Surgery_Schwartz_14011

Surgery_Schwartz

binary outcomes, presentation of both absolute and relative effect sizes is recommendedAncillary analyses18Results of any other analyses performed, including subgroup analyses and adjusted analyses, distinguishing pre-specified from exploratoryHarms19All important harms or unintended effects in each groupDiscussion Limitations20Trial limitations, addressing sources of potential bias, imprecision, and, if relevant, multiplicity of analysesGeneralizability21Generalizability (external validity, applicability) of the trial findingsInterpretation22Interpretation consistent with results, balancing benefits and harms, and considering other relevant evidenceOther Information Registration23Registration number and name of trial registryProtocol24Where the full trial protocol can be accessed, if availableFunding25Sources of funding and other support (such as supply of drugs), role of fundersFigure 51-3. CONSORT checklist. (Reproduced with permission from Schulz KF, Altman DG, Moher D, et al:

Surgery_Schwartz. binary outcomes, presentation of both absolute and relative effect sizes is recommendedAncillary analyses18Results of any other analyses performed, including subgroup analyses and adjusted analyses, distinguishing pre-specified from exploratoryHarms19All important harms or unintended effects in each groupDiscussion Limitations20Trial limitations, addressing sources of potential bias, imprecision, and, if relevant, multiplicity of analysesGeneralizability21Generalizability (external validity, applicability) of the trial findingsInterpretation22Interpretation consistent with results, balancing benefits and harms, and considering other relevant evidenceOther Information Registration23Registration number and name of trial registryProtocol24Where the full trial protocol can be accessed, if availableFunding25Sources of funding and other support (such as supply of drugs), role of fundersFigure 51-3. CONSORT checklist. (Reproduced with permission from Schulz KF, Altman DG, Moher D, et al:

Surgery_Schwartz_14012

Surgery_Schwartz

availableFunding25Sources of funding and other support (such as supply of drugs), role of fundersFigure 51-3. CONSORT checklist. (Reproduced with permission from Schulz KF, Altman DG, Moher D, et al: CONSORT 2010 statement: updated guidelines for reporting parallel group randomised trials, Int J Surg. 2011;9(8):672-677.)Brunicardi_Ch51_p2137-p2152.indd 214528/02/19 4:19 PM 2146SPECIFIC CONSIDERATIONSPART IIof randomization should always be reported and carefully ana-lyzed by the reader. Certain approaches of randomization called quasi-random allocation (date of birth, day of week, participant number, etc.) are not truly random and cannot be fully concealed from study personnel. Additionally, the concept of randomization eliminating bias is only theoretical. To truly ensure the probability of confounders being equally balanced between groups, a trial must be repeated indefinitely. Understanding this impracticality, we accept that randomization will suffice.Blinding. Blinding aims

Surgery_Schwartz. availableFunding25Sources of funding and other support (such as supply of drugs), role of fundersFigure 51-3. CONSORT checklist. (Reproduced with permission from Schulz KF, Altman DG, Moher D, et al: CONSORT 2010 statement: updated guidelines for reporting parallel group randomised trials, Int J Surg. 2011;9(8):672-677.)Brunicardi_Ch51_p2137-p2152.indd 214528/02/19 4:19 PM 2146SPECIFIC CONSIDERATIONSPART IIof randomization should always be reported and carefully ana-lyzed by the reader. Certain approaches of randomization called quasi-random allocation (date of birth, day of week, participant number, etc.) are not truly random and cannot be fully concealed from study personnel. Additionally, the concept of randomization eliminating bias is only theoretical. To truly ensure the probability of confounders being equally balanced between groups, a trial must be repeated indefinitely. Understanding this impracticality, we accept that randomization will suffice.Blinding. Blinding aims

Surgery_Schwartz_14013

Surgery_Schwartz

of confounders being equally balanced between groups, a trial must be repeated indefinitely. Understanding this impracticality, we accept that randomization will suffice.Blinding. Blinding aims to reduce certain biases that can affect the outcome of the study. A subject’s knowledge of the group that they were randomized can lead to a performance bias, which can influence subjective outcomes (placebo effect). Importantly, authors should be explicitly clear regarding which groups (sub-jects, clinicians, assessors) are blinded and avoid using non-specific phrases such as “double-blinded” or “triple-blinded.” Achieving blinding and minimizing bias is a major hurdle in the execution of surgical RCTs, where there are the ethical dilemmas surrounding “sham” or placebo surgery22 (though for a counter-argument, see reference no. 23). Moreover, blinding is impossible when comparing an operative versus a nonoperative intervention.Equivalence Among Groups. During accrual, randomiza-tion helps to

Surgery_Schwartz. of confounders being equally balanced between groups, a trial must be repeated indefinitely. Understanding this impracticality, we accept that randomization will suffice.Blinding. Blinding aims to reduce certain biases that can affect the outcome of the study. A subject’s knowledge of the group that they were randomized can lead to a performance bias, which can influence subjective outcomes (placebo effect). Importantly, authors should be explicitly clear regarding which groups (sub-jects, clinicians, assessors) are blinded and avoid using non-specific phrases such as “double-blinded” or “triple-blinded.” Achieving blinding and minimizing bias is a major hurdle in the execution of surgical RCTs, where there are the ethical dilemmas surrounding “sham” or placebo surgery22 (though for a counter-argument, see reference no. 23). Moreover, blinding is impossible when comparing an operative versus a nonoperative intervention.Equivalence Among Groups. During accrual, randomiza-tion helps to

Surgery_Schwartz_14014

Surgery_Schwartz

see reference no. 23). Moreover, blinding is impossible when comparing an operative versus a nonoperative intervention.Equivalence Among Groups. During accrual, randomiza-tion helps to ensure that each group in the study shares equiva-lent baseline demographics and unmeasured biases. However, throughout the study, each group should be treated equally (excluding the actual intervention) with respect to the number of clinical visits, diagnostic tests, etc. Enforcing the same pro-tocol to each study participant further decreases sources of bias and provides increased validity when performing final analysis.Completeness of Follow-Up. Attrition bias is the differences that occur between the groups when participants withdraw from the study. A pattern can usually be identified (the treatment, side effects of treatment, long follow-up time, or other factors) that leads to withdrawal from the study. These events can hinder the ability to interpret the results of the study, and researchers

Surgery_Schwartz. see reference no. 23). Moreover, blinding is impossible when comparing an operative versus a nonoperative intervention.Equivalence Among Groups. During accrual, randomiza-tion helps to ensure that each group in the study shares equiva-lent baseline demographics and unmeasured biases. However, throughout the study, each group should be treated equally (excluding the actual intervention) with respect to the number of clinical visits, diagnostic tests, etc. Enforcing the same pro-tocol to each study participant further decreases sources of bias and provides increased validity when performing final analysis.Completeness of Follow-Up. Attrition bias is the differences that occur between the groups when participants withdraw from the study. A pattern can usually be identified (the treatment, side effects of treatment, long follow-up time, or other factors) that leads to withdrawal from the study. These events can hinder the ability to interpret the results of the study, and researchers

Surgery_Schwartz_14015

Surgery_Schwartz

side effects of treatment, long follow-up time, or other factors) that leads to withdrawal from the study. These events can hinder the ability to interpret the results of the study, and researchers should consider these implications during trial design. Furthermore, the mechanism of attrition may manifest in a bias; patients who elect to remain in a study may in fact select for characteristics that affect or determine efficacy (see the following section).Accuracy of Analysis. Analyzing the results of only partici-pants who completed all follow-up visits throughout the study can lead to skewed and inaccurate conclusions. Thus, most RCTs follow the principle of intention-to-treat (ITT) analysis. ITT analysis includes study participants who underwent initial randomization assignment regardless of events that transpired after randomization; thus ITT analysis is often described as “once randomized, always analyzed.” Removal of noncompli-ers from statistical analysis may overestimate the

Surgery_Schwartz. side effects of treatment, long follow-up time, or other factors) that leads to withdrawal from the study. These events can hinder the ability to interpret the results of the study, and researchers should consider these implications during trial design. Furthermore, the mechanism of attrition may manifest in a bias; patients who elect to remain in a study may in fact select for characteristics that affect or determine efficacy (see the following section).Accuracy of Analysis. Analyzing the results of only partici-pants who completed all follow-up visits throughout the study can lead to skewed and inaccurate conclusions. Thus, most RCTs follow the principle of intention-to-treat (ITT) analysis. ITT analysis includes study participants who underwent initial randomization assignment regardless of events that transpired after randomization; thus ITT analysis is often described as “once randomized, always analyzed.” Removal of noncompli-ers from statistical analysis may overestimate the

Surgery_Schwartz_14016

Surgery_Schwartz

of events that transpired after randomization; thus ITT analysis is often described as “once randomized, always analyzed.” Removal of noncompli-ers from statistical analysis may overestimate the effect size of the intervention. Furthermore, in clinical practice, a portion of patients will be noncompliant, and thus ITT analysis will more accurately represent the overall population.External ValidityThe goal of an RCT is to show a causative relationship between an intervention and an outcome. However, to change clinical practice, the results of the RCT must be both relevant and gen-eralizable to the clinical population; this assessment is called external validity.Number Needed to Treat. The number needed to treat (NNT) is defined as the number of patients that undergo the interven-tion before a single patient benefits compared to the control group in the trial. It is computed as the inverse of the risk dif-ference between two groups. The smaller the NNT, the more efficacious a treatment.

Surgery_Schwartz. of events that transpired after randomization; thus ITT analysis is often described as “once randomized, always analyzed.” Removal of noncompli-ers from statistical analysis may overestimate the effect size of the intervention. Furthermore, in clinical practice, a portion of patients will be noncompliant, and thus ITT analysis will more accurately represent the overall population.External ValidityThe goal of an RCT is to show a causative relationship between an intervention and an outcome. However, to change clinical practice, the results of the RCT must be both relevant and gen-eralizable to the clinical population; this assessment is called external validity.Number Needed to Treat. The number needed to treat (NNT) is defined as the number of patients that undergo the interven-tion before a single patient benefits compared to the control group in the trial. It is computed as the inverse of the risk dif-ference between two groups. The smaller the NNT, the more efficacious a treatment.

Surgery_Schwartz_14017

Surgery_Schwartz

a single patient benefits compared to the control group in the trial. It is computed as the inverse of the risk dif-ference between two groups. The smaller the NNT, the more efficacious a treatment. For example, in an RCT comparing laparoscopic cholecystectomy to observation to prevent recur-rent idiopathic acute pancreatitis, the number needed to treat was five patients.24 The NNT should also be weighed against the adverse effects of the intervention.Number Needed to Harm. While NNT reports the number of patients who undergo the intervention before a single patient benefits, number needed to harm (NNH) describes how many patients undergo the intervention for one person to have an adverse event. The higher the NNH, the safer a treatment is. In general, interventions with a low NNT and high NNH are pre-ferred. However, NNT and NNH should not be used in isolation when determining the appropriateness of intervention as neither number takes into account the degree of benefit to

Surgery_Schwartz. a single patient benefits compared to the control group in the trial. It is computed as the inverse of the risk dif-ference between two groups. The smaller the NNT, the more efficacious a treatment. For example, in an RCT comparing laparoscopic cholecystectomy to observation to prevent recur-rent idiopathic acute pancreatitis, the number needed to treat was five patients.24 The NNT should also be weighed against the adverse effects of the intervention.Number Needed to Harm. While NNT reports the number of patients who undergo the intervention before a single patient benefits, number needed to harm (NNH) describes how many patients undergo the intervention for one person to have an adverse event. The higher the NNH, the safer a treatment is. In general, interventions with a low NNT and high NNH are pre-ferred. However, NNT and NNH should not be used in isolation when determining the appropriateness of intervention as neither number takes into account the degree of benefit to

Surgery_Schwartz_14018

Surgery_Schwartz

and high NNH are pre-ferred. However, NNT and NNH should not be used in isolation when determining the appropriateness of intervention as neither number takes into account the degree of benefit to harm.Generalizability of Results. RCTs have specific exclusion and inclusion criteria to recruit a study population that is homogenous with the goal of limiting sources of bias. While this method is appropriate for RCTs, the results may not directly translate to “real-world” situations with greater heterogeneity within the potential target population (see prior comment in “Hierarchies of Evidence”), leading to a potentially significant discrepancy between trial results and their implementation for day-to-day clinical decisions. In addition, RCTs often come to a conclusion that determines the best treatment for the “average” patient enrolled in the trial. However, most patients are not “average,” and therefore the proposed conclusion may not be relevant. Additional studies about the

Surgery_Schwartz. and high NNH are pre-ferred. However, NNT and NNH should not be used in isolation when determining the appropriateness of intervention as neither number takes into account the degree of benefit to harm.Generalizability of Results. RCTs have specific exclusion and inclusion criteria to recruit a study population that is homogenous with the goal of limiting sources of bias. While this method is appropriate for RCTs, the results may not directly translate to “real-world” situations with greater heterogeneity within the potential target population (see prior comment in “Hierarchies of Evidence”), leading to a potentially significant discrepancy between trial results and their implementation for day-to-day clinical decisions. In addition, RCTs often come to a conclusion that determines the best treatment for the “average” patient enrolled in the trial. However, most patients are not “average,” and therefore the proposed conclusion may not be relevant. Additional studies about the

Surgery_Schwartz_14019

Surgery_Schwartz

the best treatment for the “average” patient enrolled in the trial. However, most patients are not “average,” and therefore the proposed conclusion may not be relevant. Additional studies about the intervention of interest in more heterogeneous populations can help convince physicians to change their clinical practice; these correlate to phase 4 pharmaceutical trials and point to the importance of continued postpractice change data collection and analysis. More importantly, principle 3 of EBM, which states that “clinical decisions should be influenced by patient values and preference,” needs to be accounted for, especially with the implementation of a new practice guideline or pattern.Additional Challenges to Conducting a Surgical RCTIn addition to methodological issues that might limit the reli-ability of a RCT, there are also considerable logistical barriers to performing a RCT. These are not trivial factors, and they contribute heavily to the number and size of RCTs that can be

Surgery_Schwartz. the best treatment for the “average” patient enrolled in the trial. However, most patients are not “average,” and therefore the proposed conclusion may not be relevant. Additional studies about the intervention of interest in more heterogeneous populations can help convince physicians to change their clinical practice; these correlate to phase 4 pharmaceutical trials and point to the importance of continued postpractice change data collection and analysis. More importantly, principle 3 of EBM, which states that “clinical decisions should be influenced by patient values and preference,” needs to be accounted for, especially with the implementation of a new practice guideline or pattern.Additional Challenges to Conducting a Surgical RCTIn addition to methodological issues that might limit the reli-ability of a RCT, there are also considerable logistical barriers to performing a RCT. These are not trivial factors, and they contribute heavily to the number and size of RCTs that can be

Surgery_Schwartz_14020

Surgery_Schwartz

the reli-ability of a RCT, there are also considerable logistical barriers to performing a RCT. These are not trivial factors, and they contribute heavily to the number and size of RCTs that can be done, particularly in surgical populations.Recruitment. One of the most challenging aspects of an RCT is recruiting an adequate number of patients to provide a high and sufficient degree of statistical power to demonstrate a measurable difference between interventions. This becomes exponentially more difficult with the prevalence of certain rare diseases. To help overcome low accrual, many trials expand their study to other hospitals and facilities at the expense of increased heterogeneity. While this may decrease internal valid-ity, the benefit is the increase in external validity.Learning Curves and Expertise-Based Design. Pharma-ceutical-based RCTs normally have higher internal validity compared to surgical trials because of the effect of surgeon experience and technique affecting

Surgery_Schwartz. the reli-ability of a RCT, there are also considerable logistical barriers to performing a RCT. These are not trivial factors, and they contribute heavily to the number and size of RCTs that can be done, particularly in surgical populations.Recruitment. One of the most challenging aspects of an RCT is recruiting an adequate number of patients to provide a high and sufficient degree of statistical power to demonstrate a measurable difference between interventions. This becomes exponentially more difficult with the prevalence of certain rare diseases. To help overcome low accrual, many trials expand their study to other hospitals and facilities at the expense of increased heterogeneity. While this may decrease internal valid-ity, the benefit is the increase in external validity.Learning Curves and Expertise-Based Design. Pharma-ceutical-based RCTs normally have higher internal validity compared to surgical trials because of the effect of surgeon experience and technique affecting

Surgery_Schwartz_14021

Surgery_Schwartz

Curves and Expertise-Based Design. Pharma-ceutical-based RCTs normally have higher internal validity compared to surgical trials because of the effect of surgeon experience and technique affecting patient outcomes; this is especially impactful when new surgical procedures are intro-duced. While the administration of a drug is a straightforward process without measurable deviation, the same cannot be said Brunicardi_Ch51_p2137-p2152.indd 214628/02/19 4:19 PM 2147UNDERSTANDING, EVALUATING, AND USING EVIDENCE FOR SURGICAL PRACTICECHAPTER 51Table 51-3Decisions regarding the null hypothesisTABLE OF ERROR TYPES NULL HYPOTHESIS (H0) ISTRUEFALSEDecision about null hypothesis (H0) RejectType I error (false positive)Correct inference (true positive)Fail to rejectCorrect inference (true negative)Type II error (false negative)regarding surgery. Novel surgical procedures have defined learning curves even for the most experienced surgeons. During this learning process, surgeon inexperience,

Surgery_Schwartz. Curves and Expertise-Based Design. Pharma-ceutical-based RCTs normally have higher internal validity compared to surgical trials because of the effect of surgeon experience and technique affecting patient outcomes; this is especially impactful when new surgical procedures are intro-duced. While the administration of a drug is a straightforward process without measurable deviation, the same cannot be said Brunicardi_Ch51_p2137-p2152.indd 214628/02/19 4:19 PM 2147UNDERSTANDING, EVALUATING, AND USING EVIDENCE FOR SURGICAL PRACTICECHAPTER 51Table 51-3Decisions regarding the null hypothesisTABLE OF ERROR TYPES NULL HYPOTHESIS (H0) ISTRUEFALSEDecision about null hypothesis (H0) RejectType I error (false positive)Correct inference (true positive)Fail to rejectCorrect inference (true negative)Type II error (false negative)regarding surgery. Novel surgical procedures have defined learning curves even for the most experienced surgeons. During this learning process, surgeon inexperience,

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II error (false negative)regarding surgery. Novel surgical procedures have defined learning curves even for the most experienced surgeons. During this learning process, surgeon inexperience, either in technical features of the procedure or procedure-related decision-making, can lead to adverse patient outcomes. Thus, neglecting the learn-ing curve can lead to an underestimation of the success of the experimental intervention; conversely, accounting for the learn-ing curve can be necessary in assessing how a new procedure can best be disseminated across the community. Furthermore, beyond the evaluation of new procedures, even with established procedures each individual surgeon is likely to have acquired throughout his/her career unique techniques and habits when operating on patients. This heterogeneity of surgeon experience and technique can limit standardization for a trial intervention.To help solve the issue of surgeon heterogeneity and inex-perience, RCTs can employ

Surgery_Schwartz. II error (false negative)regarding surgery. Novel surgical procedures have defined learning curves even for the most experienced surgeons. During this learning process, surgeon inexperience, either in technical features of the procedure or procedure-related decision-making, can lead to adverse patient outcomes. Thus, neglecting the learn-ing curve can lead to an underestimation of the success of the experimental intervention; conversely, accounting for the learn-ing curve can be necessary in assessing how a new procedure can best be disseminated across the community. Furthermore, beyond the evaluation of new procedures, even with established procedures each individual surgeon is likely to have acquired throughout his/her career unique techniques and habits when operating on patients. This heterogeneity of surgeon experience and technique can limit standardization for a trial intervention.To help solve the issue of surgeon heterogeneity and inex-perience, RCTs can employ

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patients. This heterogeneity of surgeon experience and technique can limit standardization for a trial intervention.To help solve the issue of surgeon heterogeneity and inex-perience, RCTs can employ “expertise-based design.” In this method, patients remain randomized to either the intervention or control, but the operating surgeons are experts in the surgery they are performing. This technique is already followed during cross-specialty RCTs, such as open gastrostomy tube placement versus interventional-radiology (IR) gastrostomy tube place-ment. However, this does not model every day clinical practice because not all surgeons are considered experts in the procedure described in a particular trial.All-or-None Situation. Despite continual pressure to prove treatment effect by using a RCT, there are situations when conducting a trial does not make ethical or common sense. A famous example is from the British Medical Journal in 2003 that questioned as to why there are no RCTs evaluating

Surgery_Schwartz. patients. This heterogeneity of surgeon experience and technique can limit standardization for a trial intervention.To help solve the issue of surgeon heterogeneity and inex-perience, RCTs can employ “expertise-based design.” In this method, patients remain randomized to either the intervention or control, but the operating surgeons are experts in the surgery they are performing. This technique is already followed during cross-specialty RCTs, such as open gastrostomy tube placement versus interventional-radiology (IR) gastrostomy tube place-ment. However, this does not model every day clinical practice because not all surgeons are considered experts in the procedure described in a particular trial.All-or-None Situation. Despite continual pressure to prove treatment effect by using a RCT, there are situations when conducting a trial does not make ethical or common sense. A famous example is from the British Medical Journal in 2003 that questioned as to why there are no RCTs evaluating

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there are situations when conducting a trial does not make ethical or common sense. A famous example is from the British Medical Journal in 2003 that questioned as to why there are no RCTs evaluating the use of parachutes during gravitational free-fall.25 The authors state that the evidence to support the use of parachutes is purely observational yet it is considered a “gold standard” practice. This demonstrates the concept of an all-or-none situation, where the study population exposed to a risk experiences the outcome and none of the population experiences the outcome with the intervention. Performing an RCT on this type of situation would be dangerous and unethical, and thus purely observational data can provide a high degree of sufficient evidence.Noninferiority Trials. As reviewed earlier, trialing a new therapy compared to a placebo or sham raises serious ethical issues, especially when an effective therapy has already been established. Moreover, a portion of randomized control

Surgery_Schwartz. there are situations when conducting a trial does not make ethical or common sense. A famous example is from the British Medical Journal in 2003 that questioned as to why there are no RCTs evaluating the use of parachutes during gravitational free-fall.25 The authors state that the evidence to support the use of parachutes is purely observational yet it is considered a “gold standard” practice. This demonstrates the concept of an all-or-none situation, where the study population exposed to a risk experiences the outcome and none of the population experiences the outcome with the intervention. Performing an RCT on this type of situation would be dangerous and unethical, and thus purely observational data can provide a high degree of sufficient evidence.Noninferiority Trials. As reviewed earlier, trialing a new therapy compared to a placebo or sham raises serious ethical issues, especially when an effective therapy has already been established. Moreover, a portion of randomized control

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trialing a new therapy compared to a placebo or sham raises serious ethical issues, especially when an effective therapy has already been established. Moreover, a portion of randomized control trials today are evaluating secondary endpoints, such as quality of life, safety, and cost efficiency of a new therapy compared to the existing gold standard. These studies are called noninferiority trials, with the intent to prove efficacy that is not worse than the existing therapy. For example, a 2004 study compared open versus laparoscopic colectomy for colon cancer. The aim was to show similar oncologic endpoints with improved secondary outcomes (improved cosmesis, decreased postoperative pain, decreased hernia incidence).26 The prevalence of these trials have increased substantially from under 100 in 2005 to nearly 600 in 2015.27 The most important consideration when evaluating this type of trial is the prespecified margin of noninferiority, a value that is largely arbitrary in the

Surgery_Schwartz. trialing a new therapy compared to a placebo or sham raises serious ethical issues, especially when an effective therapy has already been established. Moreover, a portion of randomized control trials today are evaluating secondary endpoints, such as quality of life, safety, and cost efficiency of a new therapy compared to the existing gold standard. These studies are called noninferiority trials, with the intent to prove efficacy that is not worse than the existing therapy. For example, a 2004 study compared open versus laparoscopic colectomy for colon cancer. The aim was to show similar oncologic endpoints with improved secondary outcomes (improved cosmesis, decreased postoperative pain, decreased hernia incidence).26 The prevalence of these trials have increased substantially from under 100 in 2005 to nearly 600 in 2015.27 The most important consideration when evaluating this type of trial is the prespecified margin of noninferiority, a value that is largely arbitrary in the

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under 100 in 2005 to nearly 600 in 2015.27 The most important consideration when evaluating this type of trial is the prespecified margin of noninferiority, a value that is largely arbitrary in the literature.28USE AND MISUSE OF STATISTICAL SIGNIFICANCEThe use of statistical methods is central to the scientific process; it is only through statistics that the problem of induction29 can be addressed. While this chapter is not intended to be 6a comprehensive description of statistical methods, understand-ing the appropriate application of statistical tools is critical to being able to assess the conclusions presented in the literature, and therefore we present a summary of those statistical terms that are most germane to being able to interpret a clinical study.Type I and Type II ErrorsBy necessity, statistical testing requires declaration of a null hypothesis, usually corresponding to the “default” state (i.e., no difference or the patient is healthy). The alternative hypothesis would

Surgery_Schwartz. under 100 in 2005 to nearly 600 in 2015.27 The most important consideration when evaluating this type of trial is the prespecified margin of noninferiority, a value that is largely arbitrary in the literature.28USE AND MISUSE OF STATISTICAL SIGNIFICANCEThe use of statistical methods is central to the scientific process; it is only through statistics that the problem of induction29 can be addressed. While this chapter is not intended to be 6a comprehensive description of statistical methods, understand-ing the appropriate application of statistical tools is critical to being able to assess the conclusions presented in the literature, and therefore we present a summary of those statistical terms that are most germane to being able to interpret a clinical study.Type I and Type II ErrorsBy necessity, statistical testing requires declaration of a null hypothesis, usually corresponding to the “default” state (i.e., no difference or the patient is healthy). The alternative hypothesis would

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statistical testing requires declaration of a null hypothesis, usually corresponding to the “default” state (i.e., no difference or the patient is healthy). The alternative hypothesis would then negate the stated null hypothesis (i.e., there is a dif-ference or the patient is unhealthy). The result of a statistical significance test may either reject or accept the null hypothesis, and this result can correspond with the true state (a correct deci-sion) or not correspond with the true state (an error). Two types of error are possible (Table 51-3).Type I Error. A type I error occurs when the null hypothesis is rejected but is actually true in the population. This may also be referred to as a false positive. The type I error rate, denoted by the Greek letter α (alpha), is the probability that the null hypothesis is rejected given that it is true. The error rate may also be referred to as the significance level, and often a value of 0.05, or 5%, is frequently used in the literature.Type

Surgery_Schwartz. statistical testing requires declaration of a null hypothesis, usually corresponding to the “default” state (i.e., no difference or the patient is healthy). The alternative hypothesis would then negate the stated null hypothesis (i.e., there is a dif-ference or the patient is unhealthy). The result of a statistical significance test may either reject or accept the null hypothesis, and this result can correspond with the true state (a correct deci-sion) or not correspond with the true state (an error). Two types of error are possible (Table 51-3).Type I Error. A type I error occurs when the null hypothesis is rejected but is actually true in the population. This may also be referred to as a false positive. The type I error rate, denoted by the Greek letter α (alpha), is the probability that the null hypothesis is rejected given that it is true. The error rate may also be referred to as the significance level, and often a value of 0.05, or 5%, is frequently used in the literature.Type

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the null hypothesis is rejected given that it is true. The error rate may also be referred to as the significance level, and often a value of 0.05, or 5%, is frequently used in the literature.Type II Error. A type II error is the failure to reject the null hypothesis when the null hypothesis is false. This error may also be referred to as a false negative. The type II error rate is denoted by the Greek letter β (beta), and is related to the power of a study. Power can range from 0 to 1, and as power increases, there is decreasing probability of making a type II error. Power is related to three main factors: (a) the statistical significance criterion of the study, (b) the magnitude of the effect of interest, and (c) the sample size used to detect the effect. Power analysis can be used to calculate the minimum sample size required for a study so that one can be likely to detect an effect of a given size.P ValuesThe P value was an innovation most closely associated with Sir Ronald

Surgery_Schwartz. the null hypothesis is rejected given that it is true. The error rate may also be referred to as the significance level, and often a value of 0.05, or 5%, is frequently used in the literature.Type II Error. A type II error is the failure to reject the null hypothesis when the null hypothesis is false. This error may also be referred to as a false negative. The type II error rate is denoted by the Greek letter β (beta), and is related to the power of a study. Power can range from 0 to 1, and as power increases, there is decreasing probability of making a type II error. Power is related to three main factors: (a) the statistical significance criterion of the study, (b) the magnitude of the effect of interest, and (c) the sample size used to detect the effect. Power analysis can be used to calculate the minimum sample size required for a study so that one can be likely to detect an effect of a given size.P ValuesThe P value was an innovation most closely associated with Sir Ronald

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to calculate the minimum sample size required for a study so that one can be likely to detect an effect of a given size.P ValuesThe P value was an innovation most closely associated with Sir Ronald Fisher, one of the founders of modern statistics. The definition of a P value is the probability of an observed result given the assumption that the null hypothesis is true. The arbi-trary value established for a result having statistical significance rather than “pure chance” is less than 1 in 20 defined as a P value less than 0.05.30 Put differently, the chance of making a false-positive conclusion is 5% at a P value of 0.05 (type I error). This risk of making a false-positive conclusion is called a “type I error.” Importantly, the P value reported in the study is specific for that study’s patient sample and may not be gen-eralizable to the overall population. The probability of a false positive report not actually having an association depends not Brunicardi_Ch51_p2137-p2152.indd

Surgery_Schwartz. to calculate the minimum sample size required for a study so that one can be likely to detect an effect of a given size.P ValuesThe P value was an innovation most closely associated with Sir Ronald Fisher, one of the founders of modern statistics. The definition of a P value is the probability of an observed result given the assumption that the null hypothesis is true. The arbi-trary value established for a result having statistical significance rather than “pure chance” is less than 1 in 20 defined as a P value less than 0.05.30 Put differently, the chance of making a false-positive conclusion is 5% at a P value of 0.05 (type I error). This risk of making a false-positive conclusion is called a “type I error.” Importantly, the P value reported in the study is specific for that study’s patient sample and may not be gen-eralizable to the overall population. The probability of a false positive report not actually having an association depends not Brunicardi_Ch51_p2137-p2152.indd

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patient sample and may not be gen-eralizable to the overall population. The probability of a false positive report not actually having an association depends not Brunicardi_Ch51_p2137-p2152.indd 214728/02/19 4:19 PM 2148SPECIFIC CONSIDERATIONSPART IIonly on the associated P value, but also the prior probability that the association is real and the statistical power of the given study.31,32 The basis of this is due to perpetual undersampling of all possible relationships in a given scientific domain. This will inherently lead to type I errors with respect to all clinical pos-sibilities. Recently, statisticians have postulated that utilizing a P value of 0.05 will lead to wrong conclusions at least 30% of the time and may be even higher with underpowered studies.33The use of P values also categorizes statistical conclusions in a binary format. Should a P value of 0.049 be significant but a 0.051 not be significant? Furthermore, P values provide no insight into the effect size being

Surgery_Schwartz. patient sample and may not be gen-eralizable to the overall population. The probability of a false positive report not actually having an association depends not Brunicardi_Ch51_p2137-p2152.indd 214728/02/19 4:19 PM 2148SPECIFIC CONSIDERATIONSPART IIonly on the associated P value, but also the prior probability that the association is real and the statistical power of the given study.31,32 The basis of this is due to perpetual undersampling of all possible relationships in a given scientific domain. This will inherently lead to type I errors with respect to all clinical pos-sibilities. Recently, statisticians have postulated that utilizing a P value of 0.05 will lead to wrong conclusions at least 30% of the time and may be even higher with underpowered studies.33The use of P values also categorizes statistical conclusions in a binary format. Should a P value of 0.049 be significant but a 0.051 not be significant? Furthermore, P values provide no insight into the effect size being

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categorizes statistical conclusions in a binary format. Should a P value of 0.049 be significant but a 0.051 not be significant? Furthermore, P values provide no insight into the effect size being measured. Simply, an intervention may be statistically significant but lack any clinical significance. Purely utilizing a P value to determine the value of research findings without assessing the effect size, confidence interval, and power of the study can be misleading.Despite these flaws identified in P values, the frequency of their appearance in modern literature has continued to increase.34 Each reader should be carefully skeptical of P values and await replication with similar significance for confirmation. Fisher did not anticipate or endorse the use of the modern P <0.05 criteria. Rather, he envisioned that experiments would be repeated until the investigator was sure that he or she had learned how to use the experimental intervention to get a predictable result.Alternative to P

Surgery_Schwartz. categorizes statistical conclusions in a binary format. Should a P value of 0.049 be significant but a 0.051 not be significant? Furthermore, P values provide no insight into the effect size being measured. Simply, an intervention may be statistically significant but lack any clinical significance. Purely utilizing a P value to determine the value of research findings without assessing the effect size, confidence interval, and power of the study can be misleading.Despite these flaws identified in P values, the frequency of their appearance in modern literature has continued to increase.34 Each reader should be carefully skeptical of P values and await replication with similar significance for confirmation. Fisher did not anticipate or endorse the use of the modern P <0.05 criteria. Rather, he envisioned that experiments would be repeated until the investigator was sure that he or she had learned how to use the experimental intervention to get a predictable result.Alternative to P

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he envisioned that experiments would be repeated until the investigator was sure that he or she had learned how to use the experimental intervention to get a predictable result.Alternative to P ValuesOne potential alternative to Fisher’s approach and the limita-tion of P values is Bayesian statistics. The common element of Bayesian statistics is to provide a probability of a hypothesis being true by using prior knowledge or empirical data to esti-mate four probabilities:1. The probability that the hypothesis is true.2. The probability that the hypothesis is true given the observed data.3. The probability that the alternative hypothesis is true.4. The probability that the data would have been observed if the alternative hypothesis is true.These parameters are used to calculate a Bayes factor, or a ratio of the likelihood probability of two competing hypotheses. One difficulty for many studies is that there can be very little reli-able data that can be used to estimate these probability

Surgery_Schwartz. he envisioned that experiments would be repeated until the investigator was sure that he or she had learned how to use the experimental intervention to get a predictable result.Alternative to P ValuesOne potential alternative to Fisher’s approach and the limita-tion of P values is Bayesian statistics. The common element of Bayesian statistics is to provide a probability of a hypothesis being true by using prior knowledge or empirical data to esti-mate four probabilities:1. The probability that the hypothesis is true.2. The probability that the hypothesis is true given the observed data.3. The probability that the alternative hypothesis is true.4. The probability that the data would have been observed if the alternative hypothesis is true.These parameters are used to calculate a Bayes factor, or a ratio of the likelihood probability of two competing hypotheses. One difficulty for many studies is that there can be very little reli-able data that can be used to estimate these probability

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or a ratio of the likelihood probability of two competing hypotheses. One difficulty for many studies is that there can be very little reli-able data that can be used to estimate these probability parameters.It is important to remember that both P values and Bayes factors are mathematically defined entities, and many of the issues that have arisen with P values are due to how they are interpreted by scientists and clinicians. A false interpretation of a Bayes fac-tor is just as troublesome as a false interpretation of a P value.HOW DO THE TOOLS OF EBM PERFORM?As mentioned previously, GRADE has been widely adopted by national and international medical societies, health-related branches of government, healthcare regulatory bodies, and online medical resources such as UpToDate.16 Widespread use of the system has emphasized consistency in the rating of guidelines and an easy to understand strength assessment based upon evi-dence quality. However, at the heart of any EBM system is a

Surgery_Schwartz. or a ratio of the likelihood probability of two competing hypotheses. One difficulty for many studies is that there can be very little reli-able data that can be used to estimate these probability parameters.It is important to remember that both P values and Bayes factors are mathematically defined entities, and many of the issues that have arisen with P values are due to how they are interpreted by scientists and clinicians. A false interpretation of a Bayes fac-tor is just as troublesome as a false interpretation of a P value.HOW DO THE TOOLS OF EBM PERFORM?As mentioned previously, GRADE has been widely adopted by national and international medical societies, health-related branches of government, healthcare regulatory bodies, and online medical resources such as UpToDate.16 Widespread use of the system has emphasized consistency in the rating of guidelines and an easy to understand strength assessment based upon evi-dence quality. However, at the heart of any EBM system is a

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use of the system has emphasized consistency in the rating of guidelines and an easy to understand strength assessment based upon evi-dence quality. However, at the heart of any EBM system is a central paradox: as systems have evolved during the EBM move-ment, there is no evidence that the systems themselves are reliable.7External ConsistencyGRADE is one of several EBM systems that aim to evaluate evidence and create recommendations, but it is unknown how it compares with other previously established systems.The GRADE Working Group attempted to address this question by comparing six different systems (The American College of Chest Physicians Evidence-Based Guidelines, Australian National Health and Medical Research Council Guidelines, Oxford Centre for Evidence-Based Medicine, Scottish Intercollegiate Guidelines Network, U.S. Preventive Services Task Force Recommendations, U.S. Task Force on Community Preventive Services Recommendations) on 12 criteria to assess the overall usefulness

Surgery_Schwartz. use of the system has emphasized consistency in the rating of guidelines and an easy to understand strength assessment based upon evi-dence quality. However, at the heart of any EBM system is a central paradox: as systems have evolved during the EBM move-ment, there is no evidence that the systems themselves are reliable.7External ConsistencyGRADE is one of several EBM systems that aim to evaluate evidence and create recommendations, but it is unknown how it compares with other previously established systems.The GRADE Working Group attempted to address this question by comparing six different systems (The American College of Chest Physicians Evidence-Based Guidelines, Australian National Health and Medical Research Council Guidelines, Oxford Centre for Evidence-Based Medicine, Scottish Intercollegiate Guidelines Network, U.S. Preventive Services Task Force Recommendations, U.S. Task Force on Community Preventive Services Recommendations) on 12 criteria to assess the overall usefulness

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Guidelines Network, U.S. Preventive Services Task Force Recommendations, U.S. Task Force on Community Preventive Services Recommendations) on 12 criteria to assess the overall usefulness of each approach. The authors found that there was poor agreement about the sensibility of the six systems.35 Given that there is no agreed upon or proven gold standard, one may be concerned about the lack of external consistency among different systems. GRADE was constructed to overcome these issues; however, the system’s ability to do so has never been formally assessed.The example of the Surviving Sepsis Campaign (SSC), an important attempt to produce guidelines to improve the care of patients with sepsis or septic shock, suggests that GRADE has not overcome these problems. The endorsement of the SSC by many influential organizations underscores its importance. Nonetheless, the SSC illustrates some of the important difficul-ties with grading in general and with the GRADE system (Box: Examples of

Surgery_Schwartz. Guidelines Network, U.S. Preventive Services Task Force Recommendations, U.S. Task Force on Community Preventive Services Recommendations) on 12 criteria to assess the overall usefulness of each approach. The authors found that there was poor agreement about the sensibility of the six systems.35 Given that there is no agreed upon or proven gold standard, one may be concerned about the lack of external consistency among different systems. GRADE was constructed to overcome these issues; however, the system’s ability to do so has never been formally assessed.The example of the Surviving Sepsis Campaign (SSC), an important attempt to produce guidelines to improve the care of patients with sepsis or septic shock, suggests that GRADE has not overcome these problems. The endorsement of the SSC by many influential organizations underscores its importance. Nonetheless, the SSC illustrates some of the important difficul-ties with grading in general and with the GRADE system (Box: Examples of

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by many influential organizations underscores its importance. Nonetheless, the SSC illustrates some of the important difficul-ties with grading in general and with the GRADE system (Box: Examples of Inconsistent Use of EBM).Examples of Inconsistent Use of EBMSurviving Sepsis Campaign• The Surviving Sepsis Campaign recommended rapid use of intravenous antibiotics in their 2004 guidelines, which was given a grade of “E,”36 corresponding to a recommenda-tion based upon level IV or V evidence, or the lowest levels possible.• In the 2008 update, the same recommendation was given; however, it was given a grade of 1B/1D (depend-ing on if shock was present), corresponding to a “strong” recommendation.37• Between 2004 and 2008, three additional studies were published; however, none were randomized controlled trials or came to conclusions that were different than the numerous studies that were published prior to 2004.38-40 Internal ConsistencyIn 2005, the GRADE working group published a pilot

Surgery_Schwartz. by many influential organizations underscores its importance. Nonetheless, the SSC illustrates some of the important difficul-ties with grading in general and with the GRADE system (Box: Examples of Inconsistent Use of EBM).Examples of Inconsistent Use of EBMSurviving Sepsis Campaign• The Surviving Sepsis Campaign recommended rapid use of intravenous antibiotics in their 2004 guidelines, which was given a grade of “E,”36 corresponding to a recommenda-tion based upon level IV or V evidence, or the lowest levels possible.• In the 2008 update, the same recommendation was given; however, it was given a grade of 1B/1D (depend-ing on if shock was present), corresponding to a “strong” recommendation.37• Between 2004 and 2008, three additional studies were published; however, none were randomized controlled trials or came to conclusions that were different than the numerous studies that were published prior to 2004.38-40 Internal ConsistencyIn 2005, the GRADE working group published a pilot

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controlled trials or came to conclusions that were different than the numerous studies that were published prior to 2004.38-40 Internal ConsistencyIn 2005, the GRADE working group published a pilot study of the system which found varied levels of agreement on the qual-ity of evidence for the outcomes in question among 17 asses-sors (kappa values [Box: The Kappa Coefficient] for agreement beyond chance ranged from 0 to 0.82; mean k = 0.27; k <0 for four judgements). The authors concluded that “judgements about evidence and recommendations are complex” and stated that with discussion they could resolve most disagreements.41 No assessment of reliability or proof of usefulness has been presented regarding the GRADE system since these findings.42System IssuesThe GRADE group considers the “strength” of their recom-mendations to reflect “the degree of confidence that the desir-able effects of adherence to a recommendation outweigh the The Kappa CoefficientThe Kappa coefficient is a statistic

Surgery_Schwartz. controlled trials or came to conclusions that were different than the numerous studies that were published prior to 2004.38-40 Internal ConsistencyIn 2005, the GRADE working group published a pilot study of the system which found varied levels of agreement on the qual-ity of evidence for the outcomes in question among 17 asses-sors (kappa values [Box: The Kappa Coefficient] for agreement beyond chance ranged from 0 to 0.82; mean k = 0.27; k <0 for four judgements). The authors concluded that “judgements about evidence and recommendations are complex” and stated that with discussion they could resolve most disagreements.41 No assessment of reliability or proof of usefulness has been presented regarding the GRADE system since these findings.42System IssuesThe GRADE group considers the “strength” of their recom-mendations to reflect “the degree of confidence that the desir-able effects of adherence to a recommendation outweigh the The Kappa CoefficientThe Kappa coefficient is a statistic

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of their recom-mendations to reflect “the degree of confidence that the desir-able effects of adherence to a recommendation outweigh the The Kappa CoefficientThe Kappa coefficient is a statistic that measures inter-rater agreement for qualitative items. It is thought to be a more robust measure than simple percent agreement since κ takes into account the possibility of the agreement occurring by chance. In general, κ values < 0 indicate no agreement, 0 to 0.2 slight agreement, 0.21 to 0.4 fair agreement, 0.41 to 0.60 moderate agreement, 0.61 to 0.80 substantial agreement, and 0.81 to 1 as almost perfect agreement.Brunicardi_Ch51_p2137-p2152.indd 214828/02/19 4:19 PM 2149UNDERSTANDING, EVALUATING, AND USING EVIDENCE FOR SURGICAL PRACTICECHAPTER 51Internal ConsistencyIn 2005, the GRADE working group published a pilot study of the system which found varied levels of agreement on the qual-ity of evidence for the outcomes in question among 17 asses-sors (kappa values [Box: The Kappa

Surgery_Schwartz. of their recom-mendations to reflect “the degree of confidence that the desir-able effects of adherence to a recommendation outweigh the The Kappa CoefficientThe Kappa coefficient is a statistic that measures inter-rater agreement for qualitative items. It is thought to be a more robust measure than simple percent agreement since κ takes into account the possibility of the agreement occurring by chance. In general, κ values < 0 indicate no agreement, 0 to 0.2 slight agreement, 0.21 to 0.4 fair agreement, 0.41 to 0.60 moderate agreement, 0.61 to 0.80 substantial agreement, and 0.81 to 1 as almost perfect agreement.Brunicardi_Ch51_p2137-p2152.indd 214828/02/19 4:19 PM 2149UNDERSTANDING, EVALUATING, AND USING EVIDENCE FOR SURGICAL PRACTICECHAPTER 51Internal ConsistencyIn 2005, the GRADE working group published a pilot study of the system which found varied levels of agreement on the qual-ity of evidence for the outcomes in question among 17 asses-sors (kappa values [Box: The Kappa

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working group published a pilot study of the system which found varied levels of agreement on the qual-ity of evidence for the outcomes in question among 17 asses-sors (kappa values [Box: The Kappa Coefficient] for agreement beyond chance ranged from 0 to 0.82; mean k = 0.27; k <0 for four judgements). The authors concluded that “judgements about evidence and recommendations are complex” and stated that with discussion they could resolve most disagreements.41 No assessment of reliability or proof of usefulness has been presented regarding the GRADE system since these findings.42System IssuesThe GRADE group considers the “strength” of their recom-mendations to reflect “the degree of confidence that the desir-able effects of adherence to a recommendation outweigh the The Kappa CoefficientThe Kappa coefficient is a statistic that measures inter-rater agreement for qualitative items. It is thought to be a more robust measure than simple percent agreement since κ takes into account the

Surgery_Schwartz. working group published a pilot study of the system which found varied levels of agreement on the qual-ity of evidence for the outcomes in question among 17 asses-sors (kappa values [Box: The Kappa Coefficient] for agreement beyond chance ranged from 0 to 0.82; mean k = 0.27; k <0 for four judgements). The authors concluded that “judgements about evidence and recommendations are complex” and stated that with discussion they could resolve most disagreements.41 No assessment of reliability or proof of usefulness has been presented regarding the GRADE system since these findings.42System IssuesThe GRADE group considers the “strength” of their recom-mendations to reflect “the degree of confidence that the desir-able effects of adherence to a recommendation outweigh the The Kappa CoefficientThe Kappa coefficient is a statistic that measures inter-rater agreement for qualitative items. It is thought to be a more robust measure than simple percent agreement since κ takes into account the

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Kappa coefficient is a statistic that measures inter-rater agreement for qualitative items. It is thought to be a more robust measure than simple percent agreement since κ takes into account the possibility of the agreement occurring by chance. In general, κ values < 0 indicate no agreement, 0 to 0.2 slight agreement, 0.21 to 0.4 fair agreement, 0.41 to 0.60 moderate agreement, 0.61 to 0.80 substantial agreement, and 0.81 to 1 as almost perfect agreement.undesirable effects.”43 However, at the same time, the GRADE system allows the strength of a given recommendation to exist independent of the quality of evidence that underpins that recom-mendation. The GRADE Working Group states that “separating the judgements regarding the quality of evidence from judge-ments about the strength of recommendations is a critical and defining feature of this new grading system.”42 However, such a system allows for “high quality” evidence for small effects while “low quality” evidence with a strong

Surgery_Schwartz. Kappa coefficient is a statistic that measures inter-rater agreement for qualitative items. It is thought to be a more robust measure than simple percent agreement since κ takes into account the possibility of the agreement occurring by chance. In general, κ values < 0 indicate no agreement, 0 to 0.2 slight agreement, 0.21 to 0.4 fair agreement, 0.41 to 0.60 moderate agreement, 0.61 to 0.80 substantial agreement, and 0.81 to 1 as almost perfect agreement.undesirable effects.”43 However, at the same time, the GRADE system allows the strength of a given recommendation to exist independent of the quality of evidence that underpins that recom-mendation. The GRADE Working Group states that “separating the judgements regarding the quality of evidence from judge-ments about the strength of recommendations is a critical and defining feature of this new grading system.”42 However, such a system allows for “high quality” evidence for small effects while “low quality” evidence with a strong

Surgery_Schwartz_14041

Surgery_Schwartz

is a critical and defining feature of this new grading system.”42 However, such a system allows for “high quality” evidence for small effects while “low quality” evidence with a strong recommendation is highly implausible except for certain obvious observations.Finally, the touted advantage of the leveling process in determining the quality of evidence requires significant indi-vidual adjudication. A given study design begins at a level of quality and can be upgraded or downgraded based on several judgments regarding adequacy of blinding, follow-up, consis-tency, generalizability, and effect size. Graders are supposed to balance the level of quality using these factors, yet each is fun-damentally different and cannot be simply added or subtracted, and it is therefore up to individual judgment as to how to weigh each factor.ValidityThe GRADE system is well described in a series of publica-tions; however, none of the publications provide validation, data, or proof of the usefulness of

Surgery_Schwartz. is a critical and defining feature of this new grading system.”42 However, such a system allows for “high quality” evidence for small effects while “low quality” evidence with a strong recommendation is highly implausible except for certain obvious observations.Finally, the touted advantage of the leveling process in determining the quality of evidence requires significant indi-vidual adjudication. A given study design begins at a level of quality and can be upgraded or downgraded based on several judgments regarding adequacy of blinding, follow-up, consis-tency, generalizability, and effect size. Graders are supposed to balance the level of quality using these factors, yet each is fun-damentally different and cannot be simply added or subtracted, and it is therefore up to individual judgment as to how to weigh each factor.ValidityThe GRADE system is well described in a series of publica-tions; however, none of the publications provide validation, data, or proof of the usefulness of

Surgery_Schwartz_14042

Surgery_Schwartz

as to how to weigh each factor.ValidityThe GRADE system is well described in a series of publica-tions; however, none of the publications provide validation, data, or proof of the usefulness of the system. The only pub-lication with data is mentioned earlier, which showed a low kappa for interobserver agreement.41 Based upon the systematic tenets of EBM and lack of literature-based proof for the effec-tiveness of GRADE, there would not be a basis for its use in creating recommendations. For example, no RCT assessing the effect of using EBM on patient outcomes has been undertaken. Therefore, EBM does not satisfy its own requirements and is, ironically, a form of systematic expert opinion. There is no data to suggest that systematic EBM approaches are superior to the decision-making capabilities of competent physicians with knowledge of the recent medical literature.Implications of EBMThe GRADE Working Group suggests that “strong recommen-dations should require little debate and would

Surgery_Schwartz. as to how to weigh each factor.ValidityThe GRADE system is well described in a series of publica-tions; however, none of the publications provide validation, data, or proof of the usefulness of the system. The only pub-lication with data is mentioned earlier, which showed a low kappa for interobserver agreement.41 Based upon the systematic tenets of EBM and lack of literature-based proof for the effec-tiveness of GRADE, there would not be a basis for its use in creating recommendations. For example, no RCT assessing the effect of using EBM on patient outcomes has been undertaken. Therefore, EBM does not satisfy its own requirements and is, ironically, a form of systematic expert opinion. There is no data to suggest that systematic EBM approaches are superior to the decision-making capabilities of competent physicians with knowledge of the recent medical literature.Implications of EBMThe GRADE Working Group suggests that “strong recommen-dations should require little debate and would

Surgery_Schwartz_14043

Surgery_Schwartz

of competent physicians with knowledge of the recent medical literature.Implications of EBMThe GRADE Working Group suggests that “strong recommen-dations should require little debate and would be implemented in most circumstances.”42 Although most strong recommenda-tions are likely accurate, definitive recommendations may have unintended consequences. For example, a definitive recom-mendation may have the effect of limiting debate or further research on a topic where the recommendation is misguided, and there are numerous examples where “strong” recommenda-tions were later retracted. High-level EBM recommendations concluded that antibiotic prophylaxis should be used in necro-tizing pancreatitis based upon multiple prospective randomized controlled trials, meta-analyses, and systematic reviews.14,44,45 These recommendations were later reversed, as additional tri-als showed that there was no benefit to antibiotic use in these patients.46A valid concern regarding EBM is that established

Surgery_Schwartz. of competent physicians with knowledge of the recent medical literature.Implications of EBMThe GRADE Working Group suggests that “strong recommen-dations should require little debate and would be implemented in most circumstances.”42 Although most strong recommenda-tions are likely accurate, definitive recommendations may have unintended consequences. For example, a definitive recom-mendation may have the effect of limiting debate or further research on a topic where the recommendation is misguided, and there are numerous examples where “strong” recommenda-tions were later retracted. High-level EBM recommendations concluded that antibiotic prophylaxis should be used in necro-tizing pancreatitis based upon multiple prospective randomized controlled trials, meta-analyses, and systematic reviews.14,44,45 These recommendations were later reversed, as additional tri-als showed that there was no benefit to antibiotic use in these patients.46A valid concern regarding EBM is that established

Surgery_Schwartz_14044

Surgery_Schwartz

These recommendations were later reversed, as additional tri-als showed that there was no benefit to antibiotic use in these patients.46A valid concern regarding EBM is that established systems may lead to “strong” recommendations that are hard to challenge. This may even lead to situations where life-saving prospective studies are deemed “unethical” due to the presence of high-level, strong recommendations. As such, some groups have even issued warnings about converting practice guidelines into law.47,48THE ALTERNATIVES TO EBMEBM is appealing due to its ability to reduce and cope with uncer-tainty; however, the ability to mitigate uncertainty is not without drawbacks. The various EBM systems that exist are not always consistent in their evaluation of evidence, and even a single sys-tem may assign varying grades based on several subjective fac-tors. Finally, the performance of EBM in improving patient care has never been validated. Therefore, while most certainly a useful tool, the

Surgery_Schwartz. These recommendations were later reversed, as additional tri-als showed that there was no benefit to antibiotic use in these patients.46A valid concern regarding EBM is that established systems may lead to “strong” recommendations that are hard to challenge. This may even lead to situations where life-saving prospective studies are deemed “unethical” due to the presence of high-level, strong recommendations. As such, some groups have even issued warnings about converting practice guidelines into law.47,48THE ALTERNATIVES TO EBMEBM is appealing due to its ability to reduce and cope with uncer-tainty; however, the ability to mitigate uncertainty is not without drawbacks. The various EBM systems that exist are not always consistent in their evaluation of evidence, and even a single sys-tem may assign varying grades based on several subjective fac-tors. Finally, the performance of EBM in improving patient care has never been validated. Therefore, while most certainly a useful tool, the

Surgery_Schwartz_14045

Surgery_Schwartz

may assign varying grades based on several subjective fac-tors. Finally, the performance of EBM in improving patient care has never been validated. Therefore, while most certainly a useful tool, the limitations of EBM must be recognized to avoid blind adherence to guidelines and oversimplification of the complex clinical decision making that occurs in daily clinical care.Although striving for certainty is understandable, it is con-trary to the reality of medicine in which decisions regarding indi-vidual patients are inherently complex. In fact, as science strives for “precision” and “individualized” medicine, EBM’s focus of creating guidelines to care for the “average” patient will exist as a paradox. The best physicians function on a foundation of scien-tific theory expressed in a setting of practical knowledge gained in a local context, or tacit knowledge. This is how complex phys-iology and pathology are combined to make a specific decision for an individual patient. Therefore,

Surgery_Schwartz. may assign varying grades based on several subjective fac-tors. Finally, the performance of EBM in improving patient care has never been validated. Therefore, while most certainly a useful tool, the limitations of EBM must be recognized to avoid blind adherence to guidelines and oversimplification of the complex clinical decision making that occurs in daily clinical care.Although striving for certainty is understandable, it is con-trary to the reality of medicine in which decisions regarding indi-vidual patients are inherently complex. In fact, as science strives for “precision” and “individualized” medicine, EBM’s focus of creating guidelines to care for the “average” patient will exist as a paradox. The best physicians function on a foundation of scien-tific theory expressed in a setting of practical knowledge gained in a local context, or tacit knowledge. This is how complex phys-iology and pathology are combined to make a specific decision for an individual patient. Therefore,

Surgery_Schwartz_14046

Surgery_Schwartz

of practical knowledge gained in a local context, or tacit knowledge. This is how complex phys-iology and pathology are combined to make a specific decision for an individual patient. Therefore, although it is tempting to think that EBM makes surgery more scientific, one must remem-ber that EBM itself is not founded in scientific principal.So, what is the alternative? The alternative is a common-sense application of scientific principals and healthy skepticism for the ongoing use of EBM as a guideline for practice. This allows physicians to use published guidelines, applied within the context of their practice, until a grading system has defini-tively been shown to positively affect patient outcomes or more precise application of patient data is made possible. Recommen-dations certainly can be useful information; however, clinicians should also understand that there is a nuance with respect to adherence to guidelines and that much lies outside the reaches of EBM. As such,

Surgery_Schwartz. of practical knowledge gained in a local context, or tacit knowledge. This is how complex phys-iology and pathology are combined to make a specific decision for an individual patient. Therefore, although it is tempting to think that EBM makes surgery more scientific, one must remem-ber that EBM itself is not founded in scientific principal.So, what is the alternative? The alternative is a common-sense application of scientific principals and healthy skepticism for the ongoing use of EBM as a guideline for practice. This allows physicians to use published guidelines, applied within the context of their practice, until a grading system has defini-tively been shown to positively affect patient outcomes or more precise application of patient data is made possible. Recommen-dations certainly can be useful information; however, clinicians should also understand that there is a nuance with respect to adherence to guidelines and that much lies outside the reaches of EBM. As such,

Surgery_Schwartz_14047

Surgery_Schwartz

certainly can be useful information; however, clinicians should also understand that there is a nuance with respect to adherence to guidelines and that much lies outside the reaches of EBM. As such, understanding that daily clinical practice involves hundreds of decisions that require varying proportions of explicit and tacit knowledge is important in devising a system where guidelines are flexible and receptive to continual feed-back based upon the experiences of practicing physicians.WHAT CAN RESEARCHERS DO TO IMPROVE THE VALIDITY OF RESEARCH FINDINGS?Although it is impossible to know the truth with absolute certainty, researchers can take steps to ensure that the posttest probability is maximized. First, researchers can attempt to obtain better-powered evidence. Although even high-powered, low-bias meta analyses are not perfect, they do approach a theoretical “gold standard” of research, and although increasing power is important in arriving at correct conclusions, even

Surgery_Schwartz. certainly can be useful information; however, clinicians should also understand that there is a nuance with respect to adherence to guidelines and that much lies outside the reaches of EBM. As such, understanding that daily clinical practice involves hundreds of decisions that require varying proportions of explicit and tacit knowledge is important in devising a system where guidelines are flexible and receptive to continual feed-back based upon the experiences of practicing physicians.WHAT CAN RESEARCHERS DO TO IMPROVE THE VALIDITY OF RESEARCH FINDINGS?Although it is impossible to know the truth with absolute certainty, researchers can take steps to ensure that the posttest probability is maximized. First, researchers can attempt to obtain better-powered evidence. Although even high-powered, low-bias meta analyses are not perfect, they do approach a theoretical “gold standard” of research, and although increasing power is important in arriving at correct conclusions, even

Surgery_Schwartz_14048

Surgery_Schwartz

high-powered, low-bias meta analyses are not perfect, they do approach a theoretical “gold standard” of research, and although increasing power is important in arriving at correct conclusions, even high-powered studies can have significant biases. Additionally, obtaining large-scale evidence may not be possible for many research questions.Brunicardi_Ch51_p2137-p2152.indd 214928/02/19 4:19 PM 2150SPECIFIC CONSIDERATIONSPART IICrisis of Reproducibility and Medical Reversal: Implications for EBM“You keep using that word. I do not think it means what you think it means.”—Inigo Montoya from The Princess BrideThis chapter started by noting that the landscape of scientific knowledge is constantly evolving and that this fact impacts how we use and evaluate evidence as well. This 11th edition of Schwartz’s Principles of Surgery is being produced at a particularly volatile period in biomedical research as basic assumptions as to how scientific literature determines what constitutes

Surgery_Schwartz. high-powered, low-bias meta analyses are not perfect, they do approach a theoretical “gold standard” of research, and although increasing power is important in arriving at correct conclusions, even high-powered studies can have significant biases. Additionally, obtaining large-scale evidence may not be possible for many research questions.Brunicardi_Ch51_p2137-p2152.indd 214928/02/19 4:19 PM 2150SPECIFIC CONSIDERATIONSPART IICrisis of Reproducibility and Medical Reversal: Implications for EBM“You keep using that word. I do not think it means what you think it means.”—Inigo Montoya from The Princess BrideThis chapter started by noting that the landscape of scientific knowledge is constantly evolving and that this fact impacts how we use and evaluate evidence as well. This 11th edition of Schwartz’s Principles of Surgery is being produced at a particularly volatile period in biomedical research as basic assumptions as to how scientific literature determines what constitutes

Surgery_Schwartz_14049

Surgery_Schwartz

edition of Schwartz’s Principles of Surgery is being produced at a particularly volatile period in biomedical research as basic assumptions as to how scientific literature determines what constitutes “evidence” are being reassessed in a critical fashion. We believe it does a disservice to our readers if we fail to note and describe these trends, as they directly affect the basis of this chapter. The reassessment of biomedical literature and clinical trials can be loosely grouped into two distinct, but related topics: the crisis of reproducibility and the issue of medical reversal.The Crisis of ReproducibilityOver the past decade it has become increasingly recognized that certain medical studies, held forth as index publications upon which were based either fundamental precepts of practice or to justify entire directions of drug discovery, could not be repro-duced independently. This failure strikes at a fundamental assumption of science: that well performed studies with sufficient

Surgery_Schwartz. edition of Schwartz’s Principles of Surgery is being produced at a particularly volatile period in biomedical research as basic assumptions as to how scientific literature determines what constitutes “evidence” are being reassessed in a critical fashion. We believe it does a disservice to our readers if we fail to note and describe these trends, as they directly affect the basis of this chapter. The reassessment of biomedical literature and clinical trials can be loosely grouped into two distinct, but related topics: the crisis of reproducibility and the issue of medical reversal.The Crisis of ReproducibilityOver the past decade it has become increasingly recognized that certain medical studies, held forth as index publications upon which were based either fundamental precepts of practice or to justify entire directions of drug discovery, could not be repro-duced independently. This failure strikes at a fundamental assumption of science: that well performed studies with sufficient

Surgery_Schwartz_14050

Surgery_Schwartz

or to justify entire directions of drug discovery, could not be repro-duced independently. This failure strikes at a fundamental assumption of science: that well performed studies with sufficient statistical significance represented generalizable knowledge that could be built upon. However, estimates of irreproducibility range from 75% to 90% based on mathematical inference, and practical investigations have shown as few as 0 in 52 observa-tional study findings being confirmed by randomized controlled trials (RCTs).49 Methodological errors in study design, patient selection, or research practices have been proposed as major contributing factors in the debate over replication of scientific stud-ies. However, despite the importance of replicating research findings, there is increasing concern that in modern research there is an intrinsic bias towards positive results in publication. Biases in study design, data collection, data analysis, or presentation of findings can lead to research

Surgery_Schwartz. or to justify entire directions of drug discovery, could not be repro-duced independently. This failure strikes at a fundamental assumption of science: that well performed studies with sufficient statistical significance represented generalizable knowledge that could be built upon. However, estimates of irreproducibility range from 75% to 90% based on mathematical inference, and practical investigations have shown as few as 0 in 52 observa-tional study findings being confirmed by randomized controlled trials (RCTs).49 Methodological errors in study design, patient selection, or research practices have been proposed as major contributing factors in the debate over replication of scientific stud-ies. However, despite the importance of replicating research findings, there is increasing concern that in modern research there is an intrinsic bias towards positive results in publication. Biases in study design, data collection, data analysis, or presentation of findings can lead to research

Surgery_Schwartz_14051

Surgery_Schwartz

that in modern research there is an intrinsic bias towards positive results in publication. Biases in study design, data collection, data analysis, or presentation of findings can lead to research findings when they do not truly exist. As bias increases, the positive predictive value (PPV) of a given finding being true decreases considerably. The overall effect of bias again depends on both the power and prestudy odds of a given study. In some fields, it may in fact be the case that research findings are simply a measure of the prevailing bias. Medical research operates in areas with low preand poststudy probability for true findings, meaning it may be quite common that observed effect sizes varying around the null hypothesis (what one would expect from chance alone) are simply measuring the prevailing bias of a given field.In addition to bias, the globalization of research means that at any given time it is almost a certainty that multiple research teams are investigating the same

Surgery_Schwartz. that in modern research there is an intrinsic bias towards positive results in publication. Biases in study design, data collection, data analysis, or presentation of findings can lead to research findings when they do not truly exist. As bias increases, the positive predictive value (PPV) of a given finding being true decreases considerably. The overall effect of bias again depends on both the power and prestudy odds of a given study. In some fields, it may in fact be the case that research findings are simply a measure of the prevailing bias. Medical research operates in areas with low preand poststudy probability for true findings, meaning it may be quite common that observed effect sizes varying around the null hypothesis (what one would expect from chance alone) are simply measuring the prevailing bias of a given field.In addition to bias, the globalization of research means that at any given time it is almost a certainty that multiple research teams are investigating the same

Surgery_Schwartz_14052

Surgery_Schwartz

the prevailing bias of a given field.In addition to bias, the globalization of research means that at any given time it is almost a certainty that multiple research teams are investigating the same question or topic. Despite this fact, research findings by single teams are often considered in isolation, and the first to report a finding receives significantly more attention than subsequent studies. Suppose multiple research teams are investigating a given question with the null hypothesis being that there is no difference in treatment two treatment strategies. The probability that at least one of the groups will claim a significant research finding increases, and the positive predictive value decreases as the number of research teams increases. Unfortunately, there is little way to control for this phenomenon other than increasing the power of each individual study.Due to the combination of the aforementioned factors, the current framework of research means it is quite difficult to

Surgery_Schwartz. the prevailing bias of a given field.In addition to bias, the globalization of research means that at any given time it is almost a certainty that multiple research teams are investigating the same question or topic. Despite this fact, research findings by single teams are often considered in isolation, and the first to report a finding receives significantly more attention than subsequent studies. Suppose multiple research teams are investigating a given question with the null hypothesis being that there is no difference in treatment two treatment strategies. The probability that at least one of the groups will claim a significant research finding increases, and the positive predictive value decreases as the number of research teams increases. Unfortunately, there is little way to control for this phenomenon other than increasing the power of each individual study.Due to the combination of the aforementioned factors, the current framework of research means it is quite difficult to

Surgery_Schwartz_14053

Surgery_Schwartz

for this phenomenon other than increasing the power of each individual study.Due to the combination of the aforementioned factors, the current framework of research means it is quite difficult to end up with a PPV >50%. Based on mathematical principles, even a well-constructed, adequately powered RCT with a pretest probability of 50% will arrive at a true conclusion only about 85% of the time.31 These findings limit the available literature upon which evidence-based medicine (EBM) relies and place a greater burden on practitioners when they are attempting to analyze and draw conclusions from what they find.Medical ReversalA related topic that directly impacts how EBM is carried out is that of medical reversal. This term was introduced by Vinay Prasad and Adam Cifu in 201150,51 to describe the process and pitfalls by which a previously established practice or drug falls out of favor because it is subsequently identified not to work. As such, the issue of medical reversal is impacted by

Surgery_Schwartz. for this phenomenon other than increasing the power of each individual study.Due to the combination of the aforementioned factors, the current framework of research means it is quite difficult to end up with a PPV >50%. Based on mathematical principles, even a well-constructed, adequately powered RCT with a pretest probability of 50% will arrive at a true conclusion only about 85% of the time.31 These findings limit the available literature upon which evidence-based medicine (EBM) relies and place a greater burden on practitioners when they are attempting to analyze and draw conclusions from what they find.Medical ReversalA related topic that directly impacts how EBM is carried out is that of medical reversal. This term was introduced by Vinay Prasad and Adam Cifu in 201150,51 to describe the process and pitfalls by which a previously established practice or drug falls out of favor because it is subsequently identified not to work. As such, the issue of medical reversal is impacted by

Surgery_Schwartz_14054

Surgery_Schwartz

the process and pitfalls by which a previously established practice or drug falls out of favor because it is subsequently identified not to work. As such, the issue of medical reversal is impacted by the decision for a particular therapy to become adopted in the first place (ostensibly based on the principles of EBM) and the barriers to how subsequent evi-dence (either acquired through studies, or, more importantly, upon a more critical reassessment of the basis of its initial adoption) can reverse a prior recommendation. The set of intersecting issues related to medical reversal are highly complex (interested readers are encouraged to delve into the growing list of reports on this topic), but in terms of EBM, central issues addressed in medical reversal pertain to the use of surrogate endpoints in clinical trials, the presentation/misrepresentation of clinical trial effects, the effect of bias (academic and economic) in trial reporting and dissemination, and the strength and

Surgery_Schwartz. the process and pitfalls by which a previously established practice or drug falls out of favor because it is subsequently identified not to work. As such, the issue of medical reversal is impacted by the decision for a particular therapy to become adopted in the first place (ostensibly based on the principles of EBM) and the barriers to how subsequent evi-dence (either acquired through studies, or, more importantly, upon a more critical reassessment of the basis of its initial adoption) can reverse a prior recommendation. The set of intersecting issues related to medical reversal are highly complex (interested readers are encouraged to delve into the growing list of reports on this topic), but in terms of EBM, central issues addressed in medical reversal pertain to the use of surrogate endpoints in clinical trials, the presentation/misrepresentation of clinical trial effects, the effect of bias (academic and economic) in trial reporting and dissemination, and the strength and

Surgery_Schwartz_14055

Surgery_Schwartz

endpoints in clinical trials, the presentation/misrepresentation of clinical trial effects, the effect of bias (academic and economic) in trial reporting and dissemination, and the strength and reliability of alternatives to RCTs (for all their flaws). As with the crisis of reproducibility, understanding the factors of medical reversal directly impacts what is appropriately considered “evidence” when executing EBM, placing greater responsibility on the surgical practitioner when deter-mining what is appropriate or optimal care.It should come as no surprise to the attentive reader that many of the issues related to the crisis of reproducibility and medical reversal refer back to the sources of bias and potentially perverse incentives originally noted by Francis Bacon back in 1620 (Box: The History and Sources of Bias in Biomedical Literature).Brunicardi_Ch51_p2137-p2152.indd 215028/02/19 4:19 PM 2151UNDERSTANDING, EVALUATING, AND USING EVIDENCE FOR SURGICAL PRACTICECHAPTER

Surgery_Schwartz. endpoints in clinical trials, the presentation/misrepresentation of clinical trial effects, the effect of bias (academic and economic) in trial reporting and dissemination, and the strength and reliability of alternatives to RCTs (for all their flaws). As with the crisis of reproducibility, understanding the factors of medical reversal directly impacts what is appropriately considered “evidence” when executing EBM, placing greater responsibility on the surgical practitioner when deter-mining what is appropriate or optimal care.It should come as no surprise to the attentive reader that many of the issues related to the crisis of reproducibility and medical reversal refer back to the sources of bias and potentially perverse incentives originally noted by Francis Bacon back in 1620 (Box: The History and Sources of Bias in Biomedical Literature).Brunicardi_Ch51_p2137-p2152.indd 215028/02/19 4:19 PM 2151UNDERSTANDING, EVALUATING, AND USING EVIDENCE FOR SURGICAL PRACTICECHAPTER

Surgery_Schwartz_14056

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The History and Sources of Bias in Biomedical Literature).Brunicardi_Ch51_p2137-p2152.indd 215028/02/19 4:19 PM 2151UNDERSTANDING, EVALUATING, AND USING EVIDENCE FOR SURGICAL PRACTICECHAPTER 51Second, as was noted previously, multiple teams often simultaneously address a given research question, and it is not proper to focus on any one study in isolation. Instead, clinicians should focus on the body of evidence in its entirety. A poten-tial solution would be connecting groups through networking of data. This would allow for more accurate analysis and drawing of conclusions, although it would require a significant change in the culture of academic research practices.Today, clinicians rely on the statistics provided in a scien-tific study to provide a summary of the results. We place trust and confidence that the paper’s biostatistician accurately and truthfully calculated these statistics without incorporating con-scious bias. Each article should completely answer four ques-tions

Surgery_Schwartz. The History and Sources of Bias in Biomedical Literature).Brunicardi_Ch51_p2137-p2152.indd 215028/02/19 4:19 PM 2151UNDERSTANDING, EVALUATING, AND USING EVIDENCE FOR SURGICAL PRACTICECHAPTER 51Second, as was noted previously, multiple teams often simultaneously address a given research question, and it is not proper to focus on any one study in isolation. Instead, clinicians should focus on the body of evidence in its entirety. A poten-tial solution would be connecting groups through networking of data. This would allow for more accurate analysis and drawing of conclusions, although it would require a significant change in the culture of academic research practices.Today, clinicians rely on the statistics provided in a scien-tific study to provide a summary of the results. We place trust and confidence that the paper’s biostatistician accurately and truthfully calculated these statistics without incorporating con-scious bias. Each article should completely answer four ques-tions

Surgery_Schwartz_14057

Surgery_Schwartz

and confidence that the paper’s biostatistician accurately and truthfully calculated these statistics without incorporating con-scious bias. Each article should completely answer four ques-tions regarding the results of the study:1. What is the statistical significance of the results?2. What is the effect size and is this clinical relevant?3. What is the confidence interval?4. What is the underlying power of the study to detect a mean-ingful difference?Significant progress has been made since the adoption of EBM; however, the current direction of EBM-based guidelines have focused on populations as opposed to the complex, nuanced interactions that occur on a case by case basis. Algorithmic protocols actually serve to steer the focus away from an individual patient, at times leading to a disconnect between patients and physicians when physicians propose treatment based upon guidelines that do not adhere to that patient’s goals and values. So what can surgeons do to combat this, and how

Surgery_Schwartz. and confidence that the paper’s biostatistician accurately and truthfully calculated these statistics without incorporating con-scious bias. Each article should completely answer four ques-tions regarding the results of the study:1. What is the statistical significance of the results?2. What is the effect size and is this clinical relevant?3. What is the confidence interval?4. What is the underlying power of the study to detect a mean-ingful difference?Significant progress has been made since the adoption of EBM; however, the current direction of EBM-based guidelines have focused on populations as opposed to the complex, nuanced interactions that occur on a case by case basis. Algorithmic protocols actually serve to steer the focus away from an individual patient, at times leading to a disconnect between patients and physicians when physicians propose treatment based upon guidelines that do not adhere to that patient’s goals and values. So what can surgeons do to combat this, and how

Surgery_Schwartz_14058

Surgery_Schwartz

between patients and physicians when physicians propose treatment based upon guidelines that do not adhere to that patient’s goals and values. So what can surgeons do to combat this, and how should they practice? One must ask: “What is the best course of action for this patient, in these circumstances, at this point in their illness or condition?” Therefore, evidence must be synthesized and then individualized for each patient encounter by interconnecting it with the ethics, personality, and values associated with the case at hand. Tools such as risk calculators are useful in informing discussion, but they should by no means be definitive evidence to recommend for or against a particular treatment. Judgment remains necessary in the practice of medicine, and therefore guidelines should be thought of as “rules of thumb” that require context as opposed to “rules of law.”REFERENCESEntries highlighted in bright blue are key references. 1. Bacon F, Fowler T. Bacon’s Novum Organum. Oxford:

Surgery_Schwartz. between patients and physicians when physicians propose treatment based upon guidelines that do not adhere to that patient’s goals and values. So what can surgeons do to combat this, and how should they practice? One must ask: “What is the best course of action for this patient, in these circumstances, at this point in their illness or condition?” Therefore, evidence must be synthesized and then individualized for each patient encounter by interconnecting it with the ethics, personality, and values associated with the case at hand. Tools such as risk calculators are useful in informing discussion, but they should by no means be definitive evidence to recommend for or against a particular treatment. Judgment remains necessary in the practice of medicine, and therefore guidelines should be thought of as “rules of thumb” that require context as opposed to “rules of law.”REFERENCESEntries highlighted in bright blue are key references. 1. Bacon F, Fowler T. Bacon’s Novum Organum. Oxford:

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thought of as “rules of thumb” that require context as opposed to “rules of law.”REFERENCESEntries highlighted in bright blue are key references. 1. Bacon F, Fowler T. Bacon’s Novum Organum. Oxford: Clarendon Press; 1878. 2. Djulbegovic B, Guyatt GH. Progress in evidence-based medi-cine: a quarter century on. Lancet. 2017;390(10092):415-423. Available at: http://dx.doi.org/10.1016/S0140-6736(16) 31592-6. Accessed August 27, 2018. 3. Sackett DL, Rosenberg WM, Gray JA, Haynes RB, Richardson WS. Evidence based medicine: what it is and what it isn’t. BMJ. 1996;312(7023):71-72. 4. Djulbegovic B, Guyatt GH, Ashcroft RE. Epistemologic inquiries in evidence-based medicine. Cancer Control. 2009;16(2):158-168. 5. Wente MN, Seiler CM, Uhl W, Buchler MW. Perspectives of evidence-based surgery. Dig Surg. 2003;20(4):263-269. 6. Solomon MJ, McLeod RS. Clinical studies in surgical journals—have we improved? Dis Colon Rectum. 1993;36(1):43-48. 7. Pollock AV. Surgical evaluation at the crossroads. Br

Surgery_Schwartz. thought of as “rules of thumb” that require context as opposed to “rules of law.”REFERENCESEntries highlighted in bright blue are key references. 1. Bacon F, Fowler T. Bacon’s Novum Organum. Oxford: Clarendon Press; 1878. 2. Djulbegovic B, Guyatt GH. Progress in evidence-based medi-cine: a quarter century on. Lancet. 2017;390(10092):415-423. Available at: http://dx.doi.org/10.1016/S0140-6736(16) 31592-6. Accessed August 27, 2018. 3. Sackett DL, Rosenberg WM, Gray JA, Haynes RB, Richardson WS. Evidence based medicine: what it is and what it isn’t. BMJ. 1996;312(7023):71-72. 4. Djulbegovic B, Guyatt GH, Ashcroft RE. Epistemologic inquiries in evidence-based medicine. Cancer Control. 2009;16(2):158-168. 5. Wente MN, Seiler CM, Uhl W, Buchler MW. Perspectives of evidence-based surgery. Dig Surg. 2003;20(4):263-269. 6. Solomon MJ, McLeod RS. Clinical studies in surgical journals—have we improved? Dis Colon Rectum. 1993;36(1):43-48. 7. Pollock AV. Surgical evaluation at the crossroads. Br

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2003;20(4):263-269. 6. Solomon MJ, McLeod RS. Clinical studies in surgical journals—have we improved? Dis Colon Rectum. 1993;36(1):43-48. 7. Pollock AV. Surgical evaluation at the crossroads. Br J Surg. 1993;80(8):964-966. 8. Richardson WS, Wilson MC, Nishikawa J, Hayward RS. The well-built clinical question: a key to evidence-based decisions. ACP J Club. 1995;123(3):A12-A13. 9. Whipple AO, Parsons WB, Mullins CR. Treatment of carcinoma of the ampulla of vater. Ann Surg. 1935;102(4):763-779. 10. Nissen R. A simple operation for control of reflux esophagitis (in German). Schweiz Med Wochenschr. 1956;86(suppl 20): 590-592. 11. Patsopoulos NA, Analatos AA, Ioannidis JP. Relative citation impact of various study designs in the health sciences. JAMA. 2005;293(19):2362-2366. 12. Moore FA, Feliciano DV, Andrassy RJ, et al. Early enteral feeding, compared with parenteral, reduces postoperative septic complications. The results of a meta-analysis. Ann Surg. 1992;216(2):172-183. 13. Eikelboom

Surgery_Schwartz. 2003;20(4):263-269. 6. Solomon MJ, McLeod RS. Clinical studies in surgical journals—have we improved? Dis Colon Rectum. 1993;36(1):43-48. 7. Pollock AV. Surgical evaluation at the crossroads. Br J Surg. 1993;80(8):964-966. 8. Richardson WS, Wilson MC, Nishikawa J, Hayward RS. The well-built clinical question: a key to evidence-based decisions. ACP J Club. 1995;123(3):A12-A13. 9. Whipple AO, Parsons WB, Mullins CR. Treatment of carcinoma of the ampulla of vater. Ann Surg. 1935;102(4):763-779. 10. Nissen R. A simple operation for control of reflux esophagitis (in German). Schweiz Med Wochenschr. 1956;86(suppl 20): 590-592. 11. Patsopoulos NA, Analatos AA, Ioannidis JP. Relative citation impact of various study designs in the health sciences. JAMA. 2005;293(19):2362-2366. 12. Moore FA, Feliciano DV, Andrassy RJ, et al. Early enteral feeding, compared with parenteral, reduces postoperative septic complications. The results of a meta-analysis. Ann Surg. 1992;216(2):172-183. 13. Eikelboom

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DV, Andrassy RJ, et al. Early enteral feeding, compared with parenteral, reduces postoperative septic complications. The results of a meta-analysis. Ann Surg. 1992;216(2):172-183. 13. Eikelboom JW, Karthikeyan G, Fagel N, Hirsh J. American Association of Orthopedic Surgeons and American College of Chest Physicians guidelines for venous thromboembolism prevention in hip and knee arthroplasty differ: what are the implications for clinicians and patients? Chest. 2009;135(2): 513-520. 14. Bassi C, Larvin M, Villatoro E. Antibiotic therapy for prophylaxis against infection of pancreatic necrosis in acute pancreatitis. Cochrane Database Syst Rev. 2003;(4):CD002941. 15. Guyatt GH, Oxman AD, Vist GE, et al. GRADE: an emerg-ing consensus on rating quality of evidence and strength of recommendations. BMJ. 2008;336(7650):924-926. 16. Higgins JPT, Green S, eds. Cochrane Handbook for Systematic Reviews of Interventions. Version 5.1.0. The Cochrane Collabo-ration; 2011. Available at:

Surgery_Schwartz. DV, Andrassy RJ, et al. Early enteral feeding, compared with parenteral, reduces postoperative septic complications. The results of a meta-analysis. Ann Surg. 1992;216(2):172-183. 13. Eikelboom JW, Karthikeyan G, Fagel N, Hirsh J. American Association of Orthopedic Surgeons and American College of Chest Physicians guidelines for venous thromboembolism prevention in hip and knee arthroplasty differ: what are the implications for clinicians and patients? Chest. 2009;135(2): 513-520. 14. Bassi C, Larvin M, Villatoro E. Antibiotic therapy for prophylaxis against infection of pancreatic necrosis in acute pancreatitis. Cochrane Database Syst Rev. 2003;(4):CD002941. 15. Guyatt GH, Oxman AD, Vist GE, et al. GRADE: an emerg-ing consensus on rating quality of evidence and strength of recommendations. BMJ. 2008;336(7650):924-926. 16. Higgins JPT, Green S, eds. Cochrane Handbook for Systematic Reviews of Interventions. Version 5.1.0. The Cochrane Collabo-ration; 2011. Available at:

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recommendations. BMJ. 2008;336(7650):924-926. 16. Higgins JPT, Green S, eds. Cochrane Handbook for Systematic Reviews of Interventions. Version 5.1.0. The Cochrane Collabo-ration; 2011. Available at: https://handbook-5-1.cochrane.org. Accessed August 27, 2018. 17. Delle Fave G, Kwekkeboom DJ, Van Cutsem E, et al. ENETS Consensus Guidelines for the management of patients with gastroduodenal neoplasms. Neuroendocrinology. 2012;95(2):74-87. 18. Graham R, Mancher M, Miller Wolman D, Greenfield S, Steinberg E, eds. Institute of Medicine (US) Committee on Standards for Developing Trustworthy Clinical Prac-tice Guidelines. Clinical Practice Guidelines We Can Trust. Washington DC: National Academies Press; 2011. 19. Adie S, Harris IA, Naylor JM, Mittal R. CONSORT compliance in surgical randomized trials: are we there yet? A systematic review. Ann Surg. 2013;258(6):872-878. 20. Schulz KF, Altman DG, Moher D; Consort Group. CON-SORT 2010 statement: updated guidelines for reporting par-allel

Surgery_Schwartz. recommendations. BMJ. 2008;336(7650):924-926. 16. Higgins JPT, Green S, eds. Cochrane Handbook for Systematic Reviews of Interventions. Version 5.1.0. The Cochrane Collabo-ration; 2011. Available at: https://handbook-5-1.cochrane.org. Accessed August 27, 2018. 17. Delle Fave G, Kwekkeboom DJ, Van Cutsem E, et al. ENETS Consensus Guidelines for the management of patients with gastroduodenal neoplasms. Neuroendocrinology. 2012;95(2):74-87. 18. Graham R, Mancher M, Miller Wolman D, Greenfield S, Steinberg E, eds. Institute of Medicine (US) Committee on Standards for Developing Trustworthy Clinical Prac-tice Guidelines. Clinical Practice Guidelines We Can Trust. Washington DC: National Academies Press; 2011. 19. Adie S, Harris IA, Naylor JM, Mittal R. CONSORT compliance in surgical randomized trials: are we there yet? A systematic review. Ann Surg. 2013;258(6):872-878. 20. Schulz KF, Altman DG, Moher D; Consort Group. CON-SORT 2010 statement: updated guidelines for reporting par-allel

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trials: are we there yet? A systematic review. Ann Surg. 2013;258(6):872-878. 20. Schulz KF, Altman DG, Moher D; Consort Group. CON-SORT 2010 statement: updated guidelines for reporting par-allel group randomised trials. Int J Surg. 2011;9(8):672-627. 21. Higgins JPT, Altman DG, Gøtzsche PC, et al. The Cochrane Collaboration’s tool for assessing risk of bias in randomised trials. BMJ. 2011;343:d5928. 22. Das AK. Randomised clinical trials in surgery: a look at the ethical and practical issues. Indian J Surg. 2011;73(4): 245-250. 23. Wartolowska K, Judge A, Hopewell S, et al. Use of placebo controls in the evaluation of surgery: systematic review. BMJ. 2014;348:g3253. 24. Raty S, Pulkkinen J, Nordback I, et al. Can laparoscopic cholecystectomy prevent recurrent idiopathic acute pancreatitis? A prospective randomized multicenter trial. Ann Surg. 2015; 262(5):736-741. 25. Smith GC, Pell JP. Parachute use to prevent death and major trauma related to gravitational challenge: systematic

Surgery_Schwartz. trials: are we there yet? A systematic review. Ann Surg. 2013;258(6):872-878. 20. Schulz KF, Altman DG, Moher D; Consort Group. CON-SORT 2010 statement: updated guidelines for reporting par-allel group randomised trials. Int J Surg. 2011;9(8):672-627. 21. Higgins JPT, Altman DG, Gøtzsche PC, et al. The Cochrane Collaboration’s tool for assessing risk of bias in randomised trials. BMJ. 2011;343:d5928. 22. Das AK. Randomised clinical trials in surgery: a look at the ethical and practical issues. Indian J Surg. 2011;73(4): 245-250. 23. Wartolowska K, Judge A, Hopewell S, et al. Use of placebo controls in the evaluation of surgery: systematic review. BMJ. 2014;348:g3253. 24. Raty S, Pulkkinen J, Nordback I, et al. Can laparoscopic cholecystectomy prevent recurrent idiopathic acute pancreatitis? A prospective randomized multicenter trial. Ann Surg. 2015; 262(5):736-741. 25. Smith GC, Pell JP. Parachute use to prevent death and major trauma related to gravitational challenge: systematic

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A prospective randomized multicenter trial. Ann Surg. 2015; 262(5):736-741. 25. Smith GC, Pell JP. Parachute use to prevent death and major trauma related to gravitational challenge: systematic review of randomised controlled trials. BMJ. 2003;327(7429): 1459-1461. 26. Clinical Outcomes of Surgical Therapy Study Group, Nelson H, Sargent DJ, et al. A comparison of laparoscopically assisted and open colectomy for colon cancer. N Engl J Med. 2004;350(20):2050-2059.Brunicardi_Ch51_p2137-p2152.indd 215128/02/19 4:19 PM 2152SPECIFIC CONSIDERATIONSPART II 27. Mauri L, D’Agostino RB Sr. Challenges in the design and interpretation of noninferiority trials. N Engl J Med. 2017;377(14):1357-1367. 28. Ho PM, Peterson PN, Masoudi FA. Evaluating the evi-dence: is there a rigid hierarchy? Circulation. 2008; 118(16):1675-1684. 29. Hume D, Norton DF, Norton MJ. A Treatise of Human Nature. Oxford; New York: Oxford University Press; 2000. 30. Dahiru T. P-value, a true test of statistical

Surgery_Schwartz. A prospective randomized multicenter trial. Ann Surg. 2015; 262(5):736-741. 25. Smith GC, Pell JP. Parachute use to prevent death and major trauma related to gravitational challenge: systematic review of randomised controlled trials. BMJ. 2003;327(7429): 1459-1461. 26. Clinical Outcomes of Surgical Therapy Study Group, Nelson H, Sargent DJ, et al. A comparison of laparoscopically assisted and open colectomy for colon cancer. N Engl J Med. 2004;350(20):2050-2059.Brunicardi_Ch51_p2137-p2152.indd 215128/02/19 4:19 PM 2152SPECIFIC CONSIDERATIONSPART II 27. Mauri L, D’Agostino RB Sr. Challenges in the design and interpretation of noninferiority trials. N Engl J Med. 2017;377(14):1357-1367. 28. Ho PM, Peterson PN, Masoudi FA. Evaluating the evi-dence: is there a rigid hierarchy? Circulation. 2008; 118(16):1675-1684. 29. Hume D, Norton DF, Norton MJ. A Treatise of Human Nature. Oxford; New York: Oxford University Press; 2000. 30. Dahiru T. P-value, a true test of statistical

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Circulation. 2008; 118(16):1675-1684. 29. Hume D, Norton DF, Norton MJ. A Treatise of Human Nature. Oxford; New York: Oxford University Press; 2000. 30. Dahiru T. P-value, a true test of statistical significance? A cautionary note. Ann Ib Postgrad Med. 2008;6(1):21-26. 31. Ioannidis JP. Why most published research findings are false. PLoS Med. 2005;2(8):e124. 32. Wacholder S, Chanock S, Garcia-Closas M, El Ghormli L, Rothman N. Assessing the probability that a positive report is false: an approach for molecular epidemiology studies. J Natl Cancer Inst. 2004;96(6):434-442. 33. Colquhoun D. An investigation of the false discovery rate and the misinterpretation of P values. R Soc Open Sci. 2014;1(3): 140216. 34. Chavalarias D, Wallach JD, Li AH, Ioannidis JP. Evolution of reporting P values in the biomedical literature, 1990-2015. JAMA. 2016;315(11):1141-1148. 35. Atkins D, Eccles M, Flottorp S, et al. Systems for grading the quality of evidence and the strength of recommendations I:

Surgery_Schwartz. Circulation. 2008; 118(16):1675-1684. 29. Hume D, Norton DF, Norton MJ. A Treatise of Human Nature. Oxford; New York: Oxford University Press; 2000. 30. Dahiru T. P-value, a true test of statistical significance? A cautionary note. Ann Ib Postgrad Med. 2008;6(1):21-26. 31. Ioannidis JP. Why most published research findings are false. PLoS Med. 2005;2(8):e124. 32. Wacholder S, Chanock S, Garcia-Closas M, El Ghormli L, Rothman N. Assessing the probability that a positive report is false: an approach for molecular epidemiology studies. J Natl Cancer Inst. 2004;96(6):434-442. 33. Colquhoun D. An investigation of the false discovery rate and the misinterpretation of P values. R Soc Open Sci. 2014;1(3): 140216. 34. Chavalarias D, Wallach JD, Li AH, Ioannidis JP. Evolution of reporting P values in the biomedical literature, 1990-2015. JAMA. 2016;315(11):1141-1148. 35. Atkins D, Eccles M, Flottorp S, et al. Systems for grading the quality of evidence and the strength of recommendations I:

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in the biomedical literature, 1990-2015. JAMA. 2016;315(11):1141-1148. 35. Atkins D, Eccles M, Flottorp S, et al. Systems for grading the quality of evidence and the strength of recommendations I: critical appraisal of existing approaches The GRADE Working Group. BMC Health Serv Res. 2004;4(1):38. 36. Dellinger RP, Carlet JM, Masur H, et al. Surviving Sepsis Campaign guidelines for management of severe sepsis and septic shock. Crit Care Med. 2004;32(3):858-873. 37. Dellinger RP, Levy MM, Carlet JM, et al. Surviving Sepsis Campaign: international guidelines for management of severe sepsis and septic shock: 2008. Crit Care Med. 2008;36(1): 296-327. 38. Houck PM, Bratzler DW, Nsa W, Ma A, Bartlett JG. Timing of antibiotic administration and outcomes for Medicare patients hospitalized with community-acquired pneumonia. Arch Intern Med. 2004;164(6):637-644. 39. Kumar A, Haery C, Paladugu B, et al. The duration of hypotension before the initiation of antibiotic treatment is a critical

Surgery_Schwartz. in the biomedical literature, 1990-2015. JAMA. 2016;315(11):1141-1148. 35. Atkins D, Eccles M, Flottorp S, et al. Systems for grading the quality of evidence and the strength of recommendations I: critical appraisal of existing approaches The GRADE Working Group. BMC Health Serv Res. 2004;4(1):38. 36. Dellinger RP, Carlet JM, Masur H, et al. Surviving Sepsis Campaign guidelines for management of severe sepsis and septic shock. Crit Care Med. 2004;32(3):858-873. 37. Dellinger RP, Levy MM, Carlet JM, et al. Surviving Sepsis Campaign: international guidelines for management of severe sepsis and septic shock: 2008. Crit Care Med. 2008;36(1): 296-327. 38. Houck PM, Bratzler DW, Nsa W, Ma A, Bartlett JG. Timing of antibiotic administration and outcomes for Medicare patients hospitalized with community-acquired pneumonia. Arch Intern Med. 2004;164(6):637-644. 39. Kumar A, Haery C, Paladugu B, et al. The duration of hypotension before the initiation of antibiotic treatment is a critical

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community-acquired pneumonia. Arch Intern Med. 2004;164(6):637-644. 39. Kumar A, Haery C, Paladugu B, et al. The duration of hypotension before the initiation of antibiotic treatment is a critical determinant of survival in a murine model of Escherichia coli septic shock: association with serum lactate and inflammatory cytokine levels. J Infect Dis. 2006;193(2):251-258. 40. Proulx N, Frechette D, Toye B, Chan J, Kravcik S. Delays in the administration of antibiotics are associated with mortality from adult acute bacterial meningitis. QJM. 2005;98(4):291-298. 41. Atkins D, Briss PA, Eccles M, et al. Systems for grading the quality of evidence and the strength of recommendations II: pilot study of a new system. BMC Health Serv Res. 2005;5(1):25. 42. Kavanagh BP. The GRADE system for rating clinical guidelines. PLoS Med. 2009;6(9):e1000094. 43. The GRADE Working Group. 2018. Available at: http://www .gradeworkinggroup.org. Accessed August 27, 2018. 44. Sharma VK, Howden CW. Prophylactic

Surgery_Schwartz. community-acquired pneumonia. Arch Intern Med. 2004;164(6):637-644. 39. Kumar A, Haery C, Paladugu B, et al. The duration of hypotension before the initiation of antibiotic treatment is a critical determinant of survival in a murine model of Escherichia coli septic shock: association with serum lactate and inflammatory cytokine levels. J Infect Dis. 2006;193(2):251-258. 40. Proulx N, Frechette D, Toye B, Chan J, Kravcik S. Delays in the administration of antibiotics are associated with mortality from adult acute bacterial meningitis. QJM. 2005;98(4):291-298. 41. Atkins D, Briss PA, Eccles M, et al. Systems for grading the quality of evidence and the strength of recommendations II: pilot study of a new system. BMC Health Serv Res. 2005;5(1):25. 42. Kavanagh BP. The GRADE system for rating clinical guidelines. PLoS Med. 2009;6(9):e1000094. 43. The GRADE Working Group. 2018. Available at: http://www .gradeworkinggroup.org. Accessed August 27, 2018. 44. Sharma VK, Howden CW. Prophylactic

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clinical guidelines. PLoS Med. 2009;6(9):e1000094. 43. The GRADE Working Group. 2018. Available at: http://www .gradeworkinggroup.org. Accessed August 27, 2018. 44. Sharma VK, Howden CW. Prophylactic antibiotic administration reduces sepsis and mortality in acute necrotizing pancreatitis: a meta-analysis. Pancreas. 2001;22(1):28-31. 45. Bassi C, Mangiante G, Falconi M, Salvia R, Frigerio I, Pederzoli P. Prophylaxis for septic complications in acute necrotizing pancreatitis. J Hepatobiliary Pancreat Surg. 2001;8(3):211-215. 46. Villatoro E, Mulla M, Larvin M. Antibiotic therapy for prophylaxis against infection of pancreatic necrosis in acute pancreatitis. Cochrane Database Syst Rev. 2010;(5):CD002941. 47. Fein IA, Corrato RR. Clinical practice guidelines: culture eats strategy for breakfast, lunch, and dinner. Crit Care Med. 2008;36(4):1360-1361. 48. Jacobson PD. Transforming clinical practice guidelines into legislative mandates: proceed with abundant caution. JAMA.

Surgery_Schwartz. clinical guidelines. PLoS Med. 2009;6(9):e1000094. 43. The GRADE Working Group. 2018. Available at: http://www .gradeworkinggroup.org. Accessed August 27, 2018. 44. Sharma VK, Howden CW. Prophylactic antibiotic administration reduces sepsis and mortality in acute necrotizing pancreatitis: a meta-analysis. Pancreas. 2001;22(1):28-31. 45. Bassi C, Mangiante G, Falconi M, Salvia R, Frigerio I, Pederzoli P. Prophylaxis for septic complications in acute necrotizing pancreatitis. J Hepatobiliary Pancreat Surg. 2001;8(3):211-215. 46. Villatoro E, Mulla M, Larvin M. Antibiotic therapy for prophylaxis against infection of pancreatic necrosis in acute pancreatitis. Cochrane Database Syst Rev. 2010;(5):CD002941. 47. Fein IA, Corrato RR. Clinical practice guidelines: culture eats strategy for breakfast, lunch, and dinner. Crit Care Med. 2008;36(4):1360-1361. 48. Jacobson PD. Transforming clinical practice guidelines into legislative mandates: proceed with abundant caution. JAMA.

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for breakfast, lunch, and dinner. Crit Care Med. 2008;36(4):1360-1361. 48. Jacobson PD. Transforming clinical practice guidelines into legislative mandates: proceed with abundant caution. JAMA. 2008;299(2):208-210. 49. Begley CG, Ioannidis JP. Reproducibility in science: improv-ing the standard for basic and preclinical research. Circ Res. 2015;116(1):116-126. 50. Prasad V, Cifu A. Medical reversal: why we must raise the bar before adopting new technologies. Yale J Biol Med. 2011;84(4):471-478. 51. Prasad V, Gall V, Cifu A. The frequency of medical reversal. Arch Intern Med. 2011;171(18):1675-1676.Brunicardi_Ch51_p2137-p2152.indd 215228/02/19 4:19 PM

Surgery_Schwartz. for breakfast, lunch, and dinner. Crit Care Med. 2008;36(4):1360-1361. 48. Jacobson PD. Transforming clinical practice guidelines into legislative mandates: proceed with abundant caution. JAMA. 2008;299(2):208-210. 49. Begley CG, Ioannidis JP. Reproducibility in science: improv-ing the standard for basic and preclinical research. Circ Res. 2015;116(1):116-126. 50. Prasad V, Cifu A. Medical reversal: why we must raise the bar before adopting new technologies. Yale J Biol Med. 2011;84(4):471-478. 51. Prasad V, Gall V, Cifu A. The frequency of medical reversal. Arch Intern Med. 2011;171(18):1675-1676.Brunicardi_Ch51_p2137-p2152.indd 215228/02/19 4:19 PM

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Ambulatory SurgeryMarcus Adair, Stephen Markowiak, Hollis Merrick, James R. Macho, Kara Richardson, Moriah Muscaro, Munier Nazzal, and F. Charles Brunicardi 52chapterINTRODUCTIONAmbulatory SurgeryAmbulatory Surgery is a multidisciplinary field in which surgi-cal procedures are performed on patients who are not expected to be admitted to the hospital. The field includes procedures performed on patients in the setting of hospital outpatient departments (HOPDs), freestanding ambulatory surgery cen-ters (ASCs), and those performed in doctor’s offices. The word ambulatory comes from the Latin ambulare, which means “to walk,” indicating that the patients arrived at the procedure on their own and departed after the procedure to their home environment.1Improved anesthesia techniques, the development of min-imally invasive procedures, and changes to healthcare policy (particularly healthcare funding) have been the driving fac-tors behind the increase in ambulatory surgery. Prior to these

Surgery_Schwartz. Ambulatory SurgeryMarcus Adair, Stephen Markowiak, Hollis Merrick, James R. Macho, Kara Richardson, Moriah Muscaro, Munier Nazzal, and F. Charles Brunicardi 52chapterINTRODUCTIONAmbulatory SurgeryAmbulatory Surgery is a multidisciplinary field in which surgi-cal procedures are performed on patients who are not expected to be admitted to the hospital. The field includes procedures performed on patients in the setting of hospital outpatient departments (HOPDs), freestanding ambulatory surgery cen-ters (ASCs), and those performed in doctor’s offices. The word ambulatory comes from the Latin ambulare, which means “to walk,” indicating that the patients arrived at the procedure on their own and departed after the procedure to their home environment.1Improved anesthesia techniques, the development of min-imally invasive procedures, and changes to healthcare policy (particularly healthcare funding) have been the driving fac-tors behind the increase in ambulatory surgery. Prior to these

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of min-imally invasive procedures, and changes to healthcare policy (particularly healthcare funding) have been the driving fac-tors behind the increase in ambulatory surgery. Prior to these advances, almost all surgery was performed in an inpatient hos-pital setting. Any outpatient surgeries were minor, performed in physicians’ offices, and paid for by Medicare and insurers as part of the physician’s office visit reimbursement.2Since the early 1980s, the volume of ambulatory surgery has increased in the United States.2,3 Between 1981 and 2005, the number of outpatient surgeries nationwide grew almost 10-fold to over 32.0 million per year. Outpatient procedures grew from 19% to 60% of all surgical procedures, by volume, in the United States from 1981 to 2011.2,4,5 Strong financial incentives exist for hospi-tals to shift some surgeries to an outpatient setting. The number of Medicare-certified ASCs has also increased steadily, from fewer than 300 in the early 1980s2 to 5532 in 2016

Surgery_Schwartz. of min-imally invasive procedures, and changes to healthcare policy (particularly healthcare funding) have been the driving fac-tors behind the increase in ambulatory surgery. Prior to these advances, almost all surgery was performed in an inpatient hos-pital setting. Any outpatient surgeries were minor, performed in physicians’ offices, and paid for by Medicare and insurers as part of the physician’s office visit reimbursement.2Since the early 1980s, the volume of ambulatory surgery has increased in the United States.2,3 Between 1981 and 2005, the number of outpatient surgeries nationwide grew almost 10-fold to over 32.0 million per year. Outpatient procedures grew from 19% to 60% of all surgical procedures, by volume, in the United States from 1981 to 2011.2,4,5 Strong financial incentives exist for hospi-tals to shift some surgeries to an outpatient setting. The number of Medicare-certified ASCs has also increased steadily, from fewer than 300 in the early 1980s2 to 5532 in 2016

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exist for hospi-tals to shift some surgeries to an outpatient setting. The number of Medicare-certified ASCs has also increased steadily, from fewer than 300 in the early 1980s2 to 5532 in 2016 (Fig. 52-1).5By definition, procedures at ASCs and physician’s offices are performed without the full resources of a hospital. The press has sensationalized a few adverse patient outcomes in these set-tings and made claims about the overall safety based on these isolated events. However, much of the convenience, high patient satisfaction rates, and cost-efficiency of ambulatory surgery is lost when performed in a hospital setting. Thus, the challenge underlying ambulatory surgery is performing safe operations on carefully selected patients in a manner that is patient-family–centric and economical.A majority of large hospitals also have their own outpatient surgery departments that exist within the hospital. ASCs per-form procedures faster and more efficiently than HOPDs and at higher volume

Surgery_Schwartz. exist for hospi-tals to shift some surgeries to an outpatient setting. The number of Medicare-certified ASCs has also increased steadily, from fewer than 300 in the early 1980s2 to 5532 in 2016 (Fig. 52-1).5By definition, procedures at ASCs and physician’s offices are performed without the full resources of a hospital. The press has sensationalized a few adverse patient outcomes in these set-tings and made claims about the overall safety based on these isolated events. However, much of the convenience, high patient satisfaction rates, and cost-efficiency of ambulatory surgery is lost when performed in a hospital setting. Thus, the challenge underlying ambulatory surgery is performing safe operations on carefully selected patients in a manner that is patient-family–centric and economical.A majority of large hospitals also have their own outpatient surgery departments that exist within the hospital. ASCs per-form procedures faster and more efficiently than HOPDs and at higher volume

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majority of large hospitals also have their own outpatient surgery departments that exist within the hospital. ASCs per-form procedures faster and more efficiently than HOPDs and at higher volume than both HOPDs and physicians’ offices. Addi-tionally, the number of certified, freestanding ASCs nationwide has eclipsed the total number of hospitals by more than 1000 centers.5 For these reasons, a plurality of outpatient surgical vol-ume in the United States is now performed in ASCs. It is critical for the modern surgeon to have a grasp of the unique clinical challenges and economic impacts of ambulatory surgery.Ambulatory Surgery CentersASCs are independent healthcare that offer patients the conve-nience of having surgery performed safely without admission to a hospital. ASCs provide only elective surgical services rather than emergency care. According to the Centers for Medicare & Medicaid Services (CMS), effective May 18, 2009, “ASCs are any distinct entity that operates exclusively

Surgery_Schwartz. majority of large hospitals also have their own outpatient surgery departments that exist within the hospital. ASCs per-form procedures faster and more efficiently than HOPDs and at higher volume than both HOPDs and physicians’ offices. Addi-tionally, the number of certified, freestanding ASCs nationwide has eclipsed the total number of hospitals by more than 1000 centers.5 For these reasons, a plurality of outpatient surgical vol-ume in the United States is now performed in ASCs. It is critical for the modern surgeon to have a grasp of the unique clinical challenges and economic impacts of ambulatory surgery.Ambulatory Surgery CentersASCs are independent healthcare that offer patients the conve-nience of having surgery performed safely without admission to a hospital. ASCs provide only elective surgical services rather than emergency care. According to the Centers for Medicare & Medicaid Services (CMS), effective May 18, 2009, “ASCs are any distinct entity that operates exclusively

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elective surgical services rather than emergency care. According to the Centers for Medicare & Medicaid Services (CMS), effective May 18, 2009, “ASCs are any distinct entity that operates exclusively for the purpose of providing surgical services to patients not requiring hospi-talization and which the expected duration of services would not exceed 24 hours following an admission.”4 Ambulatory sur-gery centers should not be confused with office-based surgery practices or with other outpatient centers that provide diagnos-tic services or primary healthcare, such as urgent care centers, community health centers, mobile diagnostic units, or rural health clinics. ASCs are distinguished from these other health-care facilities by (a) their use of a referral system for accept-ing patients and (b) their maintenance of a dedicated operating room. The first feature means that any patient who wants to be treated in an ambulatory surgery center must first consult a Introduction2153Ambulatory

Surgery_Schwartz. elective surgical services rather than emergency care. According to the Centers for Medicare & Medicaid Services (CMS), effective May 18, 2009, “ASCs are any distinct entity that operates exclusively for the purpose of providing surgical services to patients not requiring hospi-talization and which the expected duration of services would not exceed 24 hours following an admission.”4 Ambulatory sur-gery centers should not be confused with office-based surgery practices or with other outpatient centers that provide diagnos-tic services or primary healthcare, such as urgent care centers, community health centers, mobile diagnostic units, or rural health clinics. ASCs are distinguished from these other health-care facilities by (a) their use of a referral system for accept-ing patients and (b) their maintenance of a dedicated operating room. The first feature means that any patient who wants to be treated in an ambulatory surgery center must first consult a Introduction2153Ambulatory

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(b) their maintenance of a dedicated operating room. The first feature means that any patient who wants to be treated in an ambulatory surgery center must first consult a Introduction2153Ambulatory Surgery / 2153Ambulatory Surgery Centers / 2153Aspects Leading to Increased Utilization / 2154History of Ambulatory Surgery and Ambulatory Surgery Centers2154Procedures Performed2156Benefits of Ambulatory Surgery Centers2156Factors Contributing to Popularization of ASCs / 2157Regulation, Costs, and Quality2158Regulation / 2158Costs / 2158Quality / 2159Ownership / 2159Potential for Conflict of Interest / 2159Challenges2159Reimbursement / 2159Patient Selection / 2159ASCs vs. Hospital Outpatient Departments vs. Office-Based Surgical Suites / 2160Aging Population / 2160Conclusion2160Brunicardi_Ch52_p2153-p2162.indd 215328/02/19 4:17 PM 2154199660005000Number of ASCs4000300020001000019982000200220042006200820102012Figure 52-1. Number of Medicare-certified ambulatory surgery centers

Surgery_Schwartz. (b) their maintenance of a dedicated operating room. The first feature means that any patient who wants to be treated in an ambulatory surgery center must first consult a Introduction2153Ambulatory Surgery / 2153Ambulatory Surgery Centers / 2153Aspects Leading to Increased Utilization / 2154History of Ambulatory Surgery and Ambulatory Surgery Centers2154Procedures Performed2156Benefits of Ambulatory Surgery Centers2156Factors Contributing to Popularization of ASCs / 2157Regulation, Costs, and Quality2158Regulation / 2158Costs / 2158Quality / 2159Ownership / 2159Potential for Conflict of Interest / 2159Challenges2159Reimbursement / 2159Patient Selection / 2159ASCs vs. Hospital Outpatient Departments vs. Office-Based Surgical Suites / 2160Aging Population / 2160Conclusion2160Brunicardi_Ch52_p2153-p2162.indd 215328/02/19 4:17 PM 2154199660005000Number of ASCs4000300020001000019982000200220042006200820102012Figure 52-1. Number of Medicare-certified ambulatory surgery centers

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215328/02/19 4:17 PM 2154199660005000Number of ASCs4000300020001000019982000200220042006200820102012Figure 52-1. Number of Medicare-certified ambulatory surgery centers from 1996 to 2013.Key Points1 Define ambulatory surgery and the unique aspects of ambu-latory surgery centers (ASCs).2 Understand the history of ambulatory surgery and ASCs in the United States.3 Review the most common procedures performed in ASCs compared to those performed in a hospital setting.4 Discuss the financial benefits for patients and physicians within the structure of ASCs as they pertain to physician ownership, healthcare systems partnerships, and insurance reimbursement.5 Understand the regulatory and accreditation processes that affect ASCs.6 Predict how anticipated medical advances, technological development, and an aging population will affect the field of ambulatory surgery.primary healthcare provider (PCP) and choose to have the con-dition treated by surgery rather than an alternative approach.

Surgery_Schwartz. 215328/02/19 4:17 PM 2154199660005000Number of ASCs4000300020001000019982000200220042006200820102012Figure 52-1. Number of Medicare-certified ambulatory surgery centers from 1996 to 2013.Key Points1 Define ambulatory surgery and the unique aspects of ambu-latory surgery centers (ASCs).2 Understand the history of ambulatory surgery and ASCs in the United States.3 Review the most common procedures performed in ASCs compared to those performed in a hospital setting.4 Discuss the financial benefits for patients and physicians within the structure of ASCs as they pertain to physician ownership, healthcare systems partnerships, and insurance reimbursement.5 Understand the regulatory and accreditation processes that affect ASCs.6 Predict how anticipated medical advances, technological development, and an aging population will affect the field of ambulatory surgery.primary healthcare provider (PCP) and choose to have the con-dition treated by surgery rather than an alternative approach.

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and an aging population will affect the field of ambulatory surgery.primary healthcare provider (PCP) and choose to have the con-dition treated by surgery rather than an alternative approach. The second characteristic means that all ASCs must have at least one dedicated operating room and the equipment needed to per-form surgery safely and ensure quality patient care.1 Patients who choose to have surgery in an ASC arrive on the day of their procedure, have their surgery in a fully equipped operating room, and recover under the care of a highly-skilled anesthesia team, all without hospital admission.Aspects Leading to Increased UtilizationTechnological Developments. Improvements in anesthe-sia have facilitated the safe practice of outpatient surgery by the use of new medications, improved techniques in regional anesthesia, and better management of postoperative pain. The development of minimally invasive surgical techniques such as fiberoptic endoscopy, arthroscopy, ophthalmologic

Surgery_Schwartz. and an aging population will affect the field of ambulatory surgery.primary healthcare provider (PCP) and choose to have the con-dition treated by surgery rather than an alternative approach. The second characteristic means that all ASCs must have at least one dedicated operating room and the equipment needed to per-form surgery safely and ensure quality patient care.1 Patients who choose to have surgery in an ASC arrive on the day of their procedure, have their surgery in a fully equipped operating room, and recover under the care of a highly-skilled anesthesia team, all without hospital admission.Aspects Leading to Increased UtilizationTechnological Developments. Improvements in anesthe-sia have facilitated the safe practice of outpatient surgery by the use of new medications, improved techniques in regional anesthesia, and better management of postoperative pain. The development of minimally invasive surgical techniques such as fiberoptic endoscopy, arthroscopy, ophthalmologic

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techniques in regional anesthesia, and better management of postoperative pain. The development of minimally invasive surgical techniques such as fiberoptic endoscopy, arthroscopy, ophthalmologic procedures, and laparoscopic and robotic surgery have made it possible for patients to be discharged the on the same day as the surgery.Reduced Cost for Patients Without Compromise in Quality of Care. Ambulatory surgery facilities are highly specialized centers originating from a service model rather than the tradition hospital model. This approach allows for streamlined processes and reduced costs. Staffing is the largest cost for most healthcare facilities including ASCs, thus same-day surgery eliminates the need for overnight nursing and support staff.ASCs Offer Reduced Cost for Healthcare Systems. A review of commercial medical claims data found that annual U.S. healthcare costs are reduced by approximately $3.8 billion due to the availability of ASCs. Patients save more than $1.5

Surgery_Schwartz. techniques in regional anesthesia, and better management of postoperative pain. The development of minimally invasive surgical techniques such as fiberoptic endoscopy, arthroscopy, ophthalmologic procedures, and laparoscopic and robotic surgery have made it possible for patients to be discharged the on the same day as the surgery.Reduced Cost for Patients Without Compromise in Quality of Care. Ambulatory surgery facilities are highly specialized centers originating from a service model rather than the tradition hospital model. This approach allows for streamlined processes and reduced costs. Staffing is the largest cost for most healthcare facilities including ASCs, thus same-day surgery eliminates the need for overnight nursing and support staff.ASCs Offer Reduced Cost for Healthcare Systems. A review of commercial medical claims data found that annual U.S. healthcare costs are reduced by approximately $3.8 billion due to the availability of ASCs. Patients save more than $1.5

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Systems. A review of commercial medical claims data found that annual U.S. healthcare costs are reduced by approximately $3.8 billion due to the availability of ASCs. Patients save more than $1.5 bil-lion due to lower deductibles and coinsurance payments. Over the next decade, ASCs are expected to save the U.S. healthcare system between $32.5 and $57.6 billion. This cost reduction is driven by the fact that, in general, ASC prices are significantly lower than HOPD prices for the same procedure in all mar-kets, regardless of payer.6 Table 52-1 displays the cost savings compared to hospital outpatient departments for the most com-monly performed procedures at ASCs nationwide. While most hospitals offer outpatient surgery, ambulatory surgery centers are regarded as a superior choice for certain procedures because of facility efficiencies and price regulation under the outpatient prospective payment system.6HISTORY OF AMBULATORY SURGERY AND AMBULATORY SURGERY CENTERSAmbulatory surgical

Surgery_Schwartz. Systems. A review of commercial medical claims data found that annual U.S. healthcare costs are reduced by approximately $3.8 billion due to the availability of ASCs. Patients save more than $1.5 bil-lion due to lower deductibles and coinsurance payments. Over the next decade, ASCs are expected to save the U.S. healthcare system between $32.5 and $57.6 billion. This cost reduction is driven by the fact that, in general, ASC prices are significantly lower than HOPD prices for the same procedure in all mar-kets, regardless of payer.6 Table 52-1 displays the cost savings compared to hospital outpatient departments for the most com-monly performed procedures at ASCs nationwide. While most hospitals offer outpatient surgery, ambulatory surgery centers are regarded as a superior choice for certain procedures because of facility efficiencies and price regulation under the outpatient prospective payment system.6HISTORY OF AMBULATORY SURGERY AND AMBULATORY SURGERY CENTERSAmbulatory surgical

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procedures because of facility efficiencies and price regulation under the outpatient prospective payment system.6HISTORY OF AMBULATORY SURGERY AND AMBULATORY SURGERY CENTERSAmbulatory surgical practice traces its history from the early work of itinerant dental surgeons who traveled their circuits by horseback and trains. They frequently operated in hotel rooms and then moved on. In 1909, James Nicoll (Fig. 52-2), a pediatric surgeon in Scotland, wrote of his experiences with ambulatory anesthesia and surgery on nearly 9000 children as outpatients during a 10-year interval at Glasgow Royal Hospi-tal for Sick Children.8 Operations included cleft lip and palate repair, correction of pyloric stenosis, mastoidectomy, repair of inguinal and umbilical hernias, and management of spina bifida and depressed skull fractures. Nicoll pleaded with his fellow surgeons to perform more pediatric operations on an outpatient basis, stating that “a large number of the cases at present treated in-door

Surgery_Schwartz. procedures because of facility efficiencies and price regulation under the outpatient prospective payment system.6HISTORY OF AMBULATORY SURGERY AND AMBULATORY SURGERY CENTERSAmbulatory surgical practice traces its history from the early work of itinerant dental surgeons who traveled their circuits by horseback and trains. They frequently operated in hotel rooms and then moved on. In 1909, James Nicoll (Fig. 52-2), a pediatric surgeon in Scotland, wrote of his experiences with ambulatory anesthesia and surgery on nearly 9000 children as outpatients during a 10-year interval at Glasgow Royal Hospi-tal for Sick Children.8 Operations included cleft lip and palate repair, correction of pyloric stenosis, mastoidectomy, repair of inguinal and umbilical hernias, and management of spina bifida and depressed skull fractures. Nicoll pleaded with his fellow surgeons to perform more pediatric operations on an outpatient basis, stating that “a large number of the cases at present treated in-door

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depressed skull fractures. Nicoll pleaded with his fellow surgeons to perform more pediatric operations on an outpatient basis, stating that “a large number of the cases at present treated in-door constitutes a waste of the resources of a children’s hos-pital . . . . The results obtained in the out-patient department at a tithe [small part] of the cost are equally good.”8Ralph Waters (Fig. 52-3) was a pioneer in the field of ambulatory surgery. He developed an office-based practice in Sioux City, Iowa in 1919. Waters used nitrous oxide, morphine, and scopolamine. He believed medical conditions had to be well controlled prior to surgery and that certain medical condi-tions precluded outpatient care. In these ways, Waters’ clinic became the prototype for the modern free-standing ASC. Waters subsequently went on to establish the first academic residency program for training anesthesiologists at the University of Wisconsin.9Prior to the advent of freestanding ASCs, the concept of

Surgery_Schwartz. depressed skull fractures. Nicoll pleaded with his fellow surgeons to perform more pediatric operations on an outpatient basis, stating that “a large number of the cases at present treated in-door constitutes a waste of the resources of a children’s hos-pital . . . . The results obtained in the out-patient department at a tithe [small part] of the cost are equally good.”8Ralph Waters (Fig. 52-3) was a pioneer in the field of ambulatory surgery. He developed an office-based practice in Sioux City, Iowa in 1919. Waters used nitrous oxide, morphine, and scopolamine. He believed medical conditions had to be well controlled prior to surgery and that certain medical condi-tions precluded outpatient care. In these ways, Waters’ clinic became the prototype for the modern free-standing ASC. Waters subsequently went on to establish the first academic residency program for training anesthesiologists at the University of Wisconsin.9Prior to the advent of freestanding ASCs, the concept of

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Waters subsequently went on to establish the first academic residency program for training anesthesiologists at the University of Wisconsin.9Prior to the advent of freestanding ASCs, the concept of ambulatory surgery first needed to gain acceptance in the form of HOPDs. In 1959, Eric Webb and Horace Graves advocated out-patient surgery because of a shortage of hospital beds in Vancou-ver. The first HOPD in the United States was established in 1962 at the University of California, Los Angeles by David Cohen and John Dillon, who also sought to address a shortage of hospital beds. These efforts proved to be safe and cost-effective.9Brunicardi_Ch52_p2153-p2162.indd 215428/02/19 4:17 PM 2155AMBULATORY SURGERYCHAPTER 52Figure 52-2. James Henderson Nicoll, pediatric surgeon. (Repro-duced with permission from University of Glasgow Archives & Special Collections, University collection, GB 248 PH/PR 2475.)Figure 52-3. Ralph Milton Waters, anesthesiologist. (Used with permission from the

Surgery_Schwartz. Waters subsequently went on to establish the first academic residency program for training anesthesiologists at the University of Wisconsin.9Prior to the advent of freestanding ASCs, the concept of ambulatory surgery first needed to gain acceptance in the form of HOPDs. In 1959, Eric Webb and Horace Graves advocated out-patient surgery because of a shortage of hospital beds in Vancou-ver. The first HOPD in the United States was established in 1962 at the University of California, Los Angeles by David Cohen and John Dillon, who also sought to address a shortage of hospital beds. These efforts proved to be safe and cost-effective.9Brunicardi_Ch52_p2153-p2162.indd 215428/02/19 4:17 PM 2155AMBULATORY SURGERYCHAPTER 52Figure 52-2. James Henderson Nicoll, pediatric surgeon. (Repro-duced with permission from University of Glasgow Archives & Special Collections, University collection, GB 248 PH/PR 2475.)Figure 52-3. Ralph Milton Waters, anesthesiologist. (Used with permission from the

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with permission from University of Glasgow Archives & Special Collections, University collection, GB 248 PH/PR 2475.)Figure 52-3. Ralph Milton Waters, anesthesiologist. (Used with permission from the American Society of Anesthesiologists.)Table 52-1Comparison of top 10 procedures performed at ASCs vs. hospitals nationwideTOP 10 PROCEDURES PERFORMED AT AMBULATORY SURGICAL CENTERS BY VOLUME AND CPT CODENUMBER PERFORMEDAVG PAY PER CLAIMSAVINGS AT ASCTOP 10 PROCEDURES PERFORMED AT HOSPITAL OUTPATIENT DEPARTMENTS (HOPD) BY VOLUME AND CPT CODENUMBER PERFORMEDAVG PAY PER CLAIM 1. Cataract surgery with intraoccular lens(66984)1155, 283$959$219 1. Subcutaneous tissue debridement (11042)841,517$213 2. Esophagogastroduodenoscopy with biopsy (43239)524,082$301$110 2. Esophagogastroduodenoscopy with biopsy (43239)628,900$411 3. Colonoscopy and biopsy (45380)416,218$352$172 3. Aspiration/injection of joint (20610)578,407$141 4. Colonoscopy with lesion removal (45385)331,565$401$20 4. Cataract

Surgery_Schwartz. with permission from University of Glasgow Archives & Special Collections, University collection, GB 248 PH/PR 2475.)Figure 52-3. Ralph Milton Waters, anesthesiologist. (Used with permission from the American Society of Anesthesiologists.)Table 52-1Comparison of top 10 procedures performed at ASCs vs. hospitals nationwideTOP 10 PROCEDURES PERFORMED AT AMBULATORY SURGICAL CENTERS BY VOLUME AND CPT CODENUMBER PERFORMEDAVG PAY PER CLAIMSAVINGS AT ASCTOP 10 PROCEDURES PERFORMED AT HOSPITAL OUTPATIENT DEPARTMENTS (HOPD) BY VOLUME AND CPT CODENUMBER PERFORMEDAVG PAY PER CLAIM 1. Cataract surgery with intraoccular lens(66984)1155, 283$959$219 1. Subcutaneous tissue debridement (11042)841,517$213 2. Esophagogastroduodenoscopy with biopsy (43239)524,082$301$110 2. Esophagogastroduodenoscopy with biopsy (43239)628,900$411 3. Colonoscopy and biopsy (45380)416,218$352$172 3. Aspiration/injection of joint (20610)578,407$141 4. Colonoscopy with lesion removal (45385)331,565$401$20 4. Cataract

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biopsy (43239)628,900$411 3. Colonoscopy and biopsy (45380)416,218$352$172 3. Aspiration/injection of joint (20610)578,407$141 4. Colonoscopy with lesion removal (45385)331,565$401$20 4. Cataract surgery with IOL implant (66984)512,191$1,178 5. Spine epidural injection foraminal (64483)282,962$335 5. Colonoscopy and biopsy (45380)472,886$524 6. Postlaser cataract surgery capsulotomy (66821)275,760$227 6. Colonoscopy with lesion removal (45385)350,001$421 7. Spine epidural injection lumbar, sacral (62311)210,159$358$120 7. Spine epidural injection lumbar, sacral (62311)326,956$478 8. Injection, paravertebral facet joint (64493)174,450$306 8. Insertion of temporary bladder catheter (51702)308,614$69 9. Diagnostic colonoscopy (45378)157,951$401$100 9. Appl. of multilayer compression system (29581)303,026$9710. Colorectal screening, high-risk individual (G0105)128,181$33310. Diagnostic colonoscopy (45378)253,350$501The first truly freestanding ASC, “SurgiCenter,” was opened in

Surgery_Schwartz. biopsy (43239)628,900$411 3. Colonoscopy and biopsy (45380)416,218$352$172 3. Aspiration/injection of joint (20610)578,407$141 4. Colonoscopy with lesion removal (45385)331,565$401$20 4. Cataract surgery with IOL implant (66984)512,191$1,178 5. Spine epidural injection foraminal (64483)282,962$335 5. Colonoscopy and biopsy (45380)472,886$524 6. Postlaser cataract surgery capsulotomy (66821)275,760$227 6. Colonoscopy with lesion removal (45385)350,001$421 7. Spine epidural injection lumbar, sacral (62311)210,159$358$120 7. Spine epidural injection lumbar, sacral (62311)326,956$478 8. Injection, paravertebral facet joint (64493)174,450$306 8. Insertion of temporary bladder catheter (51702)308,614$69 9. Diagnostic colonoscopy (45378)157,951$401$100 9. Appl. of multilayer compression system (29581)303,026$9710. Colorectal screening, high-risk individual (G0105)128,181$33310. Diagnostic colonoscopy (45378)253,350$501The first truly freestanding ASC, “SurgiCenter,” was opened in

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system (29581)303,026$9710. Colorectal screening, high-risk individual (G0105)128,181$33310. Diagnostic colonoscopy (45378)253,350$501The first truly freestanding ASC, “SurgiCenter,” was opened in Phoenix, Arizona by Wallace A. Reed and John L. Ford in 1970 (Fig. 52-4). Reed and Ford were committed to pro-viding timely, convenient, and comfortable surgical services to patients in their community, and therefore, avoiding more imper-sonal venues like regular hospitals. Prior to opening SurgiCen-ter, Reed and Ford were frustrated with having patients wait 6 weeks or more to get elective surgery, and in some cases, found surgeries canceled because the rooms booked were needed for emergencies.9Brunicardi_Ch52_p2153-p2162.indd 215528/02/19 4:17 PM 2156SPECIFIC CONSIDERATIONSPART IIFigure 52-4. Image of “SurgiCenter” in 1970. (Used with permission from Banner Health.)Figure 52-5. George Isaac Minimally Invasive Surgery Center at the University of Toledo Medical Center. (Used with

Surgery_Schwartz. system (29581)303,026$9710. Colorectal screening, high-risk individual (G0105)128,181$33310. Diagnostic colonoscopy (45378)253,350$501The first truly freestanding ASC, “SurgiCenter,” was opened in Phoenix, Arizona by Wallace A. Reed and John L. Ford in 1970 (Fig. 52-4). Reed and Ford were committed to pro-viding timely, convenient, and comfortable surgical services to patients in their community, and therefore, avoiding more imper-sonal venues like regular hospitals. Prior to opening SurgiCen-ter, Reed and Ford were frustrated with having patients wait 6 weeks or more to get elective surgery, and in some cases, found surgeries canceled because the rooms booked were needed for emergencies.9Brunicardi_Ch52_p2153-p2162.indd 215528/02/19 4:17 PM 2156SPECIFIC CONSIDERATIONSPART IIFigure 52-4. Image of “SurgiCenter” in 1970. (Used with permission from Banner Health.)Figure 52-5. George Isaac Minimally Invasive Surgery Center at the University of Toledo Medical Center. (Used with

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52-4. Image of “SurgiCenter” in 1970. (Used with permission from Banner Health.)Figure 52-5. George Isaac Minimally Invasive Surgery Center at the University of Toledo Medical Center. (Used with permission from University of Toledo.)In its first 6 months, Surgicenter performed more than 1200 operations by 153 surgeons. No adverse cardiac events occurred during the procedures, and only one patient was hos-pitalized following surgery (due to poorly controlled diabetes, not because of the operation itself).10 SurgiCenter’s incredible success resulted in more than 400 visitors touring the facility in the first year in order to learn about the new model for patient care.11 Reed and Ford realized that a tremendous need existed for freestanding, independent ASCs. According to Reed, this propelled the formation of what eventually became the Ambula-tory Surgery Center Association (ASCA), a major credentialing body within the field of ambulatory surgery.11The Orkand Report of 1976, a U.S.

Surgery_Schwartz. 52-4. Image of “SurgiCenter” in 1970. (Used with permission from Banner Health.)Figure 52-5. George Isaac Minimally Invasive Surgery Center at the University of Toledo Medical Center. (Used with permission from University of Toledo.)In its first 6 months, Surgicenter performed more than 1200 operations by 153 surgeons. No adverse cardiac events occurred during the procedures, and only one patient was hos-pitalized following surgery (due to poorly controlled diabetes, not because of the operation itself).10 SurgiCenter’s incredible success resulted in more than 400 visitors touring the facility in the first year in order to learn about the new model for patient care.11 Reed and Ford realized that a tremendous need existed for freestanding, independent ASCs. According to Reed, this propelled the formation of what eventually became the Ambula-tory Surgery Center Association (ASCA), a major credentialing body within the field of ambulatory surgery.11The Orkand Report of 1976, a U.S.

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the formation of what eventually became the Ambula-tory Surgery Center Association (ASCA), a major credentialing body within the field of ambulatory surgery.11The Orkand Report of 1976, a U.S. government–spon-sored study of outpatient surgery, concluded that ambulatory surgical facilities can significantly reduce costs while main-taining the same high quality of surgical and anesthetic care achieved in hospitals.12The Society for Ambulatory Anesthesia (SAMBA) was established in 1984 to further the development of ambulatory anes-thesiology as a subspecialty. The field continued to advance with the publication of Wetchler’s Anesthesia for Ambulatory Surgery in 1985, the introduction of the journal Ambulatory Surgery in 1993, and with the first state requiring accreditation for all outpatient facilities (California in 1996). Many other states have since adopted these high standards and require accreditation of ASCs. CMS now requires certification for all ASCs (Fig. 52-5 and

Surgery_Schwartz. the formation of what eventually became the Ambula-tory Surgery Center Association (ASCA), a major credentialing body within the field of ambulatory surgery.11The Orkand Report of 1976, a U.S. government–spon-sored study of outpatient surgery, concluded that ambulatory surgical facilities can significantly reduce costs while main-taining the same high quality of surgical and anesthetic care achieved in hospitals.12The Society for Ambulatory Anesthesia (SAMBA) was established in 1984 to further the development of ambulatory anes-thesiology as a subspecialty. The field continued to advance with the publication of Wetchler’s Anesthesia for Ambulatory Surgery in 1985, the introduction of the journal Ambulatory Surgery in 1993, and with the first state requiring accreditation for all outpatient facilities (California in 1996). Many other states have since adopted these high standards and require accreditation of ASCs. CMS now requires certification for all ASCs (Fig. 52-5 and

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all outpatient facilities (California in 1996). Many other states have since adopted these high standards and require accreditation of ASCs. CMS now requires certification for all ASCs (Fig. 52-5 and 52-6).5PROCEDURES PERFORMEDBy 1982, CMS had approved payments to ASCs for more than 200 procedures. Steady growth in the number of ASCs (Fig. 52-7) and the number of surgical procedures performed in the outpatient setting, including HOPDs, has continued since. Each year physicians perform more than 23 million procedures in ASCs. This shift toward outpatient procedures has increased due to advancements in medical practice and technology that have reduced the need for overnight hospital stays. Most patients, except those with complicated health conditions, can be served in the outpatient setting. Common ASC procedures include colonoscopies, cataract surgeries, tonsillectomies, and arthroscopic orthopedic surgeries. CMS currently approves and reimburses more than 3500 procedures in the ASC

Surgery_Schwartz. all outpatient facilities (California in 1996). Many other states have since adopted these high standards and require accreditation of ASCs. CMS now requires certification for all ASCs (Fig. 52-5 and 52-6).5PROCEDURES PERFORMEDBy 1982, CMS had approved payments to ASCs for more than 200 procedures. Steady growth in the number of ASCs (Fig. 52-7) and the number of surgical procedures performed in the outpatient setting, including HOPDs, has continued since. Each year physicians perform more than 23 million procedures in ASCs. This shift toward outpatient procedures has increased due to advancements in medical practice and technology that have reduced the need for overnight hospital stays. Most patients, except those with complicated health conditions, can be served in the outpatient setting. Common ASC procedures include colonoscopies, cataract surgeries, tonsillectomies, and arthroscopic orthopedic surgeries. CMS currently approves and reimburses more than 3500 procedures in the ASC

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Common ASC procedures include colonoscopies, cataract surgeries, tonsillectomies, and arthroscopic orthopedic surgeries. CMS currently approves and reimburses more than 3500 procedures in the ASC setting.5 New developments continue to expand the scope of ASCs.ASCs may perform surgeries in several specialties or dedi-cate their services to one specialty, such as eye care or sports medicine. The procedure must not pose a significant safety risk and not require an overnight stay when performed in an ASC. The types of surgical procedures performed in ASCs have undergone significant changes in recent years. Many of the early ASCs were outpatient centers for plastic surgery. Advances in minimally invasive surgical techniques in other specialties, how-ever, led to the establishment of ASCs for orthopedic, dental, and ophthalmologic procedures. See Fig. 52-8 for a recent anal-ysis of specialty services provided by ASCs nationwide.BENEFITS OF AMBULATORY SURGERY CENTERSSince their founding over

Surgery_Schwartz. Common ASC procedures include colonoscopies, cataract surgeries, tonsillectomies, and arthroscopic orthopedic surgeries. CMS currently approves and reimburses more than 3500 procedures in the ASC setting.5 New developments continue to expand the scope of ASCs.ASCs may perform surgeries in several specialties or dedi-cate their services to one specialty, such as eye care or sports medicine. The procedure must not pose a significant safety risk and not require an overnight stay when performed in an ASC. The types of surgical procedures performed in ASCs have undergone significant changes in recent years. Many of the early ASCs were outpatient centers for plastic surgery. Advances in minimally invasive surgical techniques in other specialties, how-ever, led to the establishment of ASCs for orthopedic, dental, and ophthalmologic procedures. See Fig. 52-8 for a recent anal-ysis of specialty services provided by ASCs nationwide.BENEFITS OF AMBULATORY SURGERY CENTERSSince their founding over

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dental, and ophthalmologic procedures. See Fig. 52-8 for a recent anal-ysis of specialty services provided by ASCs nationwide.BENEFITS OF AMBULATORY SURGERY CENTERSSince their founding over 40 years ago, ASCs have grown exponentially. These distinct entities have provided physi-cians an avenue to provide specialized, efficient, and quality Figure 52-6. ProMedica Parkway Surgery Center. (Used with permission from ProMedica Health Systems.)Brunicardi_Ch52_p2153-p2162.indd 215628/02/19 4:17 PM 2157AMBULATORY SURGERYCHAPTER 5219486171118694117415 (AK)2 (GU)21 (HI)12218366426347196924956081693533941724 (PR)1 (VI)67136104523318610125122779923413411626 (NH)56 (MA)10 (RI)48 (CT)269 (NJ)23 (DE)345 (MD)3 (DC)79452Figure 52-7. As of June 2017, California has 794 ASCs, making it the leading state in terms of number of ASCs. It is followed by Florida with 417 ASCs and Texas with 366 ASCs. Vermont and the U.S. Virgin Islands have the lowest number of ASCs with one

Surgery_Schwartz. dental, and ophthalmologic procedures. See Fig. 52-8 for a recent anal-ysis of specialty services provided by ASCs nationwide.BENEFITS OF AMBULATORY SURGERY CENTERSSince their founding over 40 years ago, ASCs have grown exponentially. These distinct entities have provided physi-cians an avenue to provide specialized, efficient, and quality Figure 52-6. ProMedica Parkway Surgery Center. (Used with permission from ProMedica Health Systems.)Brunicardi_Ch52_p2153-p2162.indd 215628/02/19 4:17 PM 2157AMBULATORY SURGERYCHAPTER 5219486171118694117415 (AK)2 (GU)21 (HI)12218366426347196924956081693533941724 (PR)1 (VI)67136104523318610125122779923413411626 (NH)56 (MA)10 (RI)48 (CT)269 (NJ)23 (DE)345 (MD)3 (DC)79452Figure 52-7. As of June 2017, California has 794 ASCs, making it the leading state in terms of number of ASCs. It is followed by Florida with 417 ASCs and Texas with 366 ASCs. Vermont and the U.S. Virgin Islands have the lowest number of ASCs with one

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making it the leading state in terms of number of ASCs. It is followed by Florida with 417 ASCs and Texas with 366 ASCs. Vermont and the U.S. Virgin Islands have the lowest number of ASCs with one each.13Painmanagement10%Urology5%Orthopedics15%Plastic8%Gi14%Ophthalmology30%Other18%Figure 52-8. Specialties served in ASCs. GI = gastroenterology. (Reproduced with permission from Centers for Medicare & Medicaid Services, 2011.)care to patients who need surgical procedures. Patient satisfac-tion with same-day surgery has remained relatively high since ASCs started in 1970. It is important to recognize that patients undergoing generally nonemergent surgery that does not require a hospital stay are relatively satisfied overall. Historically, the field of ambulatory surgery has been associated with very high patient satisfaction.14-15 In the future, the CMS Consumer Assessment of Healthcare Providers and Systems (CAHPS) sur-vey will report on nationwide patient satisfaction with ASCs and

Surgery_Schwartz. making it the leading state in terms of number of ASCs. It is followed by Florida with 417 ASCs and Texas with 366 ASCs. Vermont and the U.S. Virgin Islands have the lowest number of ASCs with one each.13Painmanagement10%Urology5%Orthopedics15%Plastic8%Gi14%Ophthalmology30%Other18%Figure 52-8. Specialties served in ASCs. GI = gastroenterology. (Reproduced with permission from Centers for Medicare & Medicaid Services, 2011.)care to patients who need surgical procedures. Patient satisfac-tion with same-day surgery has remained relatively high since ASCs started in 1970. It is important to recognize that patients undergoing generally nonemergent surgery that does not require a hospital stay are relatively satisfied overall. Historically, the field of ambulatory surgery has been associated with very high patient satisfaction.14-15 In the future, the CMS Consumer Assessment of Healthcare Providers and Systems (CAHPS) sur-vey will report on nationwide patient satisfaction with ASCs and

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with very high patient satisfaction.14-15 In the future, the CMS Consumer Assessment of Healthcare Providers and Systems (CAHPS) sur-vey will report on nationwide patient satisfaction with ASCs and HOPDs.16Factors Contributing to Popularization of ASCsCost. In many cases an outpatient procedure performed in an ASC is between one-half to one-third the cost as the same pro-cedure performed in a hospital. In large part, ASCs affect cost savings by eliminating overnight hospitalizations and emer-gency procedures. ASCs perform fewer extensive diagnostic tests and dispense fewer medications. These facilities are not staffed around the clock and are not encumbered by the need for expensive and highly specialized equipment as are hospitals. For example, the Medicare Payment Advisory Commission found that a cataract operation cost only $942 at an ambulatory surgery center in 2001 as opposed to $1334 at a hospital. Figures for an endoscopy and biopsy of the upper digestive tract were $429 and

Surgery_Schwartz. with very high patient satisfaction.14-15 In the future, the CMS Consumer Assessment of Healthcare Providers and Systems (CAHPS) sur-vey will report on nationwide patient satisfaction with ASCs and HOPDs.16Factors Contributing to Popularization of ASCsCost. In many cases an outpatient procedure performed in an ASC is between one-half to one-third the cost as the same pro-cedure performed in a hospital. In large part, ASCs affect cost savings by eliminating overnight hospitalizations and emer-gency procedures. ASCs perform fewer extensive diagnostic tests and dispense fewer medications. These facilities are not staffed around the clock and are not encumbered by the need for expensive and highly specialized equipment as are hospitals. For example, the Medicare Payment Advisory Commission found that a cataract operation cost only $942 at an ambulatory surgery center in 2001 as opposed to $1334 at a hospital. Figures for an endoscopy and biopsy of the upper digestive tract were $429 and

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that a cataract operation cost only $942 at an ambulatory surgery center in 2001 as opposed to $1334 at a hospital. Figures for an endoscopy and biopsy of the upper digestive tract were $429 and $359; for a diagnostic colonoscopy, $429 and $401; and for epi-dural anesthesia, $320 and $183, respectively5,7 (see Table 52-1).Organization, staffing, and specialization may play a large role in the cost differences between ASCs and HOPDs. On aver-age, patients who were treated in ASCs spend 31.8 fewer min-utes undergoing procedures than patients who were treated in HOPDs. ASCs could generate savings of $363 to $1000 per outpatient case.4Comfort. Whereas most hospitals keep patients recovering from a surgical procedure in separate rooms, in an ASC the patient usually can spend the recovery period after surgery with their loved ones. Limiting the number of delays and disruption of emergent cases allows the surgeon to spend more time with the patient in the preoperative and postoperative

Surgery_Schwartz. that a cataract operation cost only $942 at an ambulatory surgery center in 2001 as opposed to $1334 at a hospital. Figures for an endoscopy and biopsy of the upper digestive tract were $429 and $359; for a diagnostic colonoscopy, $429 and $401; and for epi-dural anesthesia, $320 and $183, respectively5,7 (see Table 52-1).Organization, staffing, and specialization may play a large role in the cost differences between ASCs and HOPDs. On aver-age, patients who were treated in ASCs spend 31.8 fewer min-utes undergoing procedures than patients who were treated in HOPDs. ASCs could generate savings of $363 to $1000 per outpatient case.4Comfort. Whereas most hospitals keep patients recovering from a surgical procedure in separate rooms, in an ASC the patient usually can spend the recovery period after surgery with their loved ones. Limiting the number of delays and disruption of emergent cases allows the surgeon to spend more time with the patient in the preoperative and postoperative

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period after surgery with their loved ones. Limiting the number of delays and disruption of emergent cases allows the surgeon to spend more time with the patient in the preoperative and postoperative areas.17-19Convenience. Because ASCs usually schedule routine cases lasting no longer than 2 hours (average 30–45 minutes), and handle no emergency cases, scheduling is typically accurate. By avoiding the logjam, ASCs reduce the waiting time for elective procedures. A study by Hair et al reviewing Medicare patients again showed freestanding ASCs performed surgeries in less time than hospital-based ASCs overall and for procedures on various anatomic systems that resulted in reduced total time spent in facility with earlier discharge.19 These results corrobo-rate the notion that freestanding ASCs tend to be more efficient than HOPDs.20 One possible advantage for patients would be that they are able to leave an ASC relatively quickly after their surgery, resulting in less time away from work

Surgery_Schwartz. period after surgery with their loved ones. Limiting the number of delays and disruption of emergent cases allows the surgeon to spend more time with the patient in the preoperative and postoperative areas.17-19Convenience. Because ASCs usually schedule routine cases lasting no longer than 2 hours (average 30–45 minutes), and handle no emergency cases, scheduling is typically accurate. By avoiding the logjam, ASCs reduce the waiting time for elective procedures. A study by Hair et al reviewing Medicare patients again showed freestanding ASCs performed surgeries in less time than hospital-based ASCs overall and for procedures on various anatomic systems that resulted in reduced total time spent in facility with earlier discharge.19 These results corrobo-rate the notion that freestanding ASCs tend to be more efficient than HOPDs.20 One possible advantage for patients would be that they are able to leave an ASC relatively quickly after their surgery, resulting in less time away from work

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tend to be more efficient than HOPDs.20 One possible advantage for patients would be that they are able to leave an ASC relatively quickly after their surgery, resulting in less time away from work and family. This may be particularly true for pediatric patients or parents.Efficiency. This advantage is particularly important to sur-geons. It takes much less time to prepare an operating room in a specialized ASC for the next patient than in a standard hospital. Improved efficiency allows the surgeon to treat more Brunicardi_Ch52_p2153-p2162.indd 215728/02/19 4:17 PM 2158SPECIFIC CONSIDERATIONSPART IIpatients in the same amount of time than he or she would be able to do in a hospital; some surgeons maintain that they can do three times the number of procedures in an ASC as they could in a hospital setting. Many doctors prefer working in an ASC because they can set the standards for staffing, safety precautions, and postoperative care, rather than having these things decided for them

Surgery_Schwartz. tend to be more efficient than HOPDs.20 One possible advantage for patients would be that they are able to leave an ASC relatively quickly after their surgery, resulting in less time away from work and family. This may be particularly true for pediatric patients or parents.Efficiency. This advantage is particularly important to sur-geons. It takes much less time to prepare an operating room in a specialized ASC for the next patient than in a standard hospital. Improved efficiency allows the surgeon to treat more Brunicardi_Ch52_p2153-p2162.indd 215728/02/19 4:17 PM 2158SPECIFIC CONSIDERATIONSPART IIpatients in the same amount of time than he or she would be able to do in a hospital; some surgeons maintain that they can do three times the number of procedures in an ASC as they could in a hospital setting. Many doctors prefer working in an ASC because they can set the standards for staffing, safety precautions, and postoperative care, rather than having these things decided for them

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a hospital setting. Many doctors prefer working in an ASC because they can set the standards for staffing, safety precautions, and postoperative care, rather than having these things decided for them by a hospital manager.1 Trentman and coauthors discuss several factors that affect patient flow and could result in differences in preoperative and recovery times for outpatient procedures between ASCs and hospitals.20 For example, compared to the situation in hospitals, in ASCs sur-geons are more likely to be assigned to a single operating room for all cases, which reduces delays; the operating room often is closer to the preoperative and recovery rooms because facili-ties are smaller; teams of staff have clearer and more consistent roles, with less personnel turnover; and staffing is not done by shifts—that is, staff members go home only after all cases are finished, which creates incentives to work quickly. In addition, hospitals may be more likely to have emergency add-on and

Surgery_Schwartz. a hospital setting. Many doctors prefer working in an ASC because they can set the standards for staffing, safety precautions, and postoperative care, rather than having these things decided for them by a hospital manager.1 Trentman and coauthors discuss several factors that affect patient flow and could result in differences in preoperative and recovery times for outpatient procedures between ASCs and hospitals.20 For example, compared to the situation in hospitals, in ASCs sur-geons are more likely to be assigned to a single operating room for all cases, which reduces delays; the operating room often is closer to the preoperative and recovery rooms because facili-ties are smaller; teams of staff have clearer and more consistent roles, with less personnel turnover; and staffing is not done by shifts—that is, staff members go home only after all cases are finished, which creates incentives to work quickly. In addition, hospitals may be more likely to have emergency add-on and

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not done by shifts—that is, staff members go home only after all cases are finished, which creates incentives to work quickly. In addition, hospitals may be more likely to have emergency add-on and bring-back cases for more complex cases that compete with outpatient procedures for operating room time.3,5,19 These dif-ferences suggest that hospitals would have to adopt a substan-tially different and highly specialized organizational model to achieve the same efficiencies as ASCs.REGULATION, COSTS, AND QUALITYRegulationHealthcare facilities in the United States are highly regulated by federal and state entities. ASCs are included in this over-sight, with both federal and state laws and regulations govern-ing all aspects of them. Independent observers evaluate the safety and quality of care provided in ASCs through three pro-cesses: Medicare certification, state licensure, and voluntary accreditation.To obtain Medicare certification, ASCs must meet the Medicare certification

Surgery_Schwartz. not done by shifts—that is, staff members go home only after all cases are finished, which creates incentives to work quickly. In addition, hospitals may be more likely to have emergency add-on and bring-back cases for more complex cases that compete with outpatient procedures for operating room time.3,5,19 These dif-ferences suggest that hospitals would have to adopt a substan-tially different and highly specialized organizational model to achieve the same efficiencies as ASCs.REGULATION, COSTS, AND QUALITYRegulationHealthcare facilities in the United States are highly regulated by federal and state entities. ASCs are included in this over-sight, with both federal and state laws and regulations govern-ing all aspects of them. Independent observers evaluate the safety and quality of care provided in ASCs through three pro-cesses: Medicare certification, state licensure, and voluntary accreditation.To obtain Medicare certification, ASCs must meet the Medicare certification

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of care provided in ASCs through three pro-cesses: Medicare certification, state licensure, and voluntary accreditation.To obtain Medicare certification, ASCs must meet the Medicare certification requirements, known as the Conditions for Coverage. These conditions include specifying standards for administration of anesthesia, quality evaluation, operating and recovery rooms, medical staff, nursing services, and other aspects of care. An ASC must have an inspection conducted by a state official or a representative of an organization that the government has authorized to conduct that inspection. These inspectors visit the ASC to verify that it meets established stan-dards. Each state determines the specific requirements ASCs must meet for licensure. An ASC does not have to be certi-fied by Medicare in order to be accredited by JCAHO; how-ever, most ASCs provide care to Medicare beneficiaries, so it is important to meet their requirements in order to be reimbursed appropriately. Medicare

Surgery_Schwartz. of care provided in ASCs through three pro-cesses: Medicare certification, state licensure, and voluntary accreditation.To obtain Medicare certification, ASCs must meet the Medicare certification requirements, known as the Conditions for Coverage. These conditions include specifying standards for administration of anesthesia, quality evaluation, operating and recovery rooms, medical staff, nursing services, and other aspects of care. An ASC must have an inspection conducted by a state official or a representative of an organization that the government has authorized to conduct that inspection. These inspectors visit the ASC to verify that it meets established stan-dards. Each state determines the specific requirements ASCs must meet for licensure. An ASC does not have to be certi-fied by Medicare in order to be accredited by JCAHO; how-ever, most ASCs provide care to Medicare beneficiaries, so it is important to meet their requirements in order to be reimbursed appropriately. Medicare

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in order to be accredited by JCAHO; how-ever, most ASCs provide care to Medicare beneficiaries, so it is important to meet their requirements in order to be reimbursed appropriately. Medicare inspection and certification of ambu-latory surgery centers is a separate process from professional accreditation.To obtain state licensure, many states have independent rules and regulations as well as associated fees. These third-party bodies can include Accreditation Association for Ambulatory Healthcare (AAAHC), American Association for Accreditation of Ambulatory Surgery Facilities (AAAASF), and the Joint Commission on Accreditation of Healthcare Organizations (JCAHO). In states for which accreditation is not mandated, ASCs may undergo voluntary accreditation through these same associations. In 37 states, any party looking to open an ASC must demonstrate a need for the ASC to exist.21 State licensure requirements generally exist for both healthcare facilities and healthcare

Surgery_Schwartz. in order to be accredited by JCAHO; how-ever, most ASCs provide care to Medicare beneficiaries, so it is important to meet their requirements in order to be reimbursed appropriately. Medicare inspection and certification of ambu-latory surgery centers is a separate process from professional accreditation.To obtain state licensure, many states have independent rules and regulations as well as associated fees. These third-party bodies can include Accreditation Association for Ambulatory Healthcare (AAAHC), American Association for Accreditation of Ambulatory Surgery Facilities (AAAASF), and the Joint Commission on Accreditation of Healthcare Organizations (JCAHO). In states for which accreditation is not mandated, ASCs may undergo voluntary accreditation through these same associations. In 37 states, any party looking to open an ASC must demonstrate a need for the ASC to exist.21 State licensure requirements generally exist for both healthcare facilities and healthcare

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associations. In 37 states, any party looking to open an ASC must demonstrate a need for the ASC to exist.21 State licensure requirements generally exist for both healthcare facilities and healthcare professionals.14There was previously controversy as to whether accredi-tation status affects safety outcomes. In multivariate analyses that controlled for facility volume and patient characteristics, patients at Joint Commission–accredited facilities were still significantly less likely to be hospitalized after colonoscopy. Specifically, compared with patients treated in nonaccredited ASCs regulated by the state agency, patients treated at accred-ited facilities were less likely to be hospitalized within 7 to 30 days after surgery.22 All accredited ASCs must meet spe-cific standards that are evaluated during on-site inspections. Patients who visit accredited ASCs can be assured that those medical facilities have rigorous checkpoints to ensure high standards.The Ambulatory Surgery Center

Surgery_Schwartz. associations. In 37 states, any party looking to open an ASC must demonstrate a need for the ASC to exist.21 State licensure requirements generally exist for both healthcare facilities and healthcare professionals.14There was previously controversy as to whether accredi-tation status affects safety outcomes. In multivariate analyses that controlled for facility volume and patient characteristics, patients at Joint Commission–accredited facilities were still significantly less likely to be hospitalized after colonoscopy. Specifically, compared with patients treated in nonaccredited ASCs regulated by the state agency, patients treated at accred-ited facilities were less likely to be hospitalized within 7 to 30 days after surgery.22 All accredited ASCs must meet spe-cific standards that are evaluated during on-site inspections. Patients who visit accredited ASCs can be assured that those medical facilities have rigorous checkpoints to ensure high standards.The Ambulatory Surgery Center

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evaluated during on-site inspections. Patients who visit accredited ASCs can be assured that those medical facilities have rigorous checkpoints to ensure high standards.The Ambulatory Surgery Center Association (ASCA) or ASC Association has an integral role to ensure top-quality healthcare from the nation’s ASCs. The ASCA was established when the two leading national ASC associations—Federated Ambulatory Surgery Association (FASA) and the American Association of Ambulatory Surgery Centers (AAASC)—merged. The ASCA serves as the national membership orga-nization as well as the advocacy group for ASCs.21 The ASCA works with legislative and regulatory bodies, liaises with other organizations to improve access, reduce the costs of healthcare, encouraging insurance coverage of outpatient procedures, and works to establish standards for ASCs. ASCA requires all of its facility members to be accredited, licensed, or Medicare certi-fied. The ASCA was instrumental in forming the accrediting body

Surgery_Schwartz. evaluated during on-site inspections. Patients who visit accredited ASCs can be assured that those medical facilities have rigorous checkpoints to ensure high standards.The Ambulatory Surgery Center Association (ASCA) or ASC Association has an integral role to ensure top-quality healthcare from the nation’s ASCs. The ASCA was established when the two leading national ASC associations—Federated Ambulatory Surgery Association (FASA) and the American Association of Ambulatory Surgery Centers (AAASC)—merged. The ASCA serves as the national membership orga-nization as well as the advocacy group for ASCs.21 The ASCA works with legislative and regulatory bodies, liaises with other organizations to improve access, reduce the costs of healthcare, encouraging insurance coverage of outpatient procedures, and works to establish standards for ASCs. ASCA requires all of its facility members to be accredited, licensed, or Medicare certi-fied. The ASCA was instrumental in forming the accrediting body