Supplementary material
Supplementary Table 1: Methods of merging evidence grading systems
Supplementary Table 2: Guidelines without quality of evidence graded n=56
Supplementary Table 3: Excluded evidence grading systems
Supplementary Table 1: Methods of merging evidence grading systems continuedSystems of grading evidence employed in individual guideline (society using this system and number of guidelines in which it is used)
Evidence systems merged into A,B,C,D for this manuscript / A = randomized control trial/meta analysis / B = single randomized control / nonrandomized / observational / C = Consensus opinion of experts, case studies, or standard-of-care / D = Not rated
System 1: A,B,C (ACG,4)1 / A - randomized control trial/meta analysis / B - single randomized control / nonrandomized / observational / C - Consensus opinion of experts, case studies, or standard-of-care
System 2: A,B,C,D (ACG,2) / A - Consistent level I evidence from randomized control trials / B – evidence would be level 2/3 cohort studies /case controls / C- Evidence would be level IV - Case series/poor quality cohort studies
D -Expert opinion
System 3: High, Moderate, Low, Very low (ACG,2 AGA,2)2 / High – further research unlikely to change confidence in effect / Moderate – further research is likely to have an important impact on estimated effect and likely to change estimate / Low – further research VERY likely to have important impact on confidence in estimated effect and likely to change estimate
Very low – any estimate is very uncertain
System 4: I,II,III,IV (ACG,3) / I – multiple well designed randomized control/meta analysis / II- single randomized control
III – trials without randomization single group prepost, cohort, time series, or matched case controlled / IV – non-experimental studies from more than one center or research group or opinion of respected authorities
System 5: 1a,1b,1c,2a,2b,2c (ACG,1) / Ia – Strong recommendation : RCT without limitations or overwhelming evidence from observation studies
2a- Weak recommendation: RCT without limitations or overwhelming evidence from observation studies / 1b –Strong recommendation: RCT with important limitations or exceptionally strong evidence from observation studies
2b –Weak recommendation: RCT with important limitations or exceptionally strong evidence from observation studies / 1c -Strong recommendation: observation studies or case series
2c – Weak recommendation: observational studies or case series
System 6: A,B,C (ACG,1) / A – strong evidence from multiple published, well controlled randomized trials or a well-designed systemic meta-analysis / B – strong evidence from at least one quality published randomized controlled trial or evidence from published, well designed, cohort, or matched case-control studies / C – consensus authoritative expert opinions based on clinical evidence or from well designed, but uncontrolled or non-randomized clinical trials
System 7: A,B,C(ACG,1 AGA,1)3 / A – homogeneous evidence from multiple well-designed randomized (therapeutic) or cohort (descriptive) controlled trials involving a number of participants to be of sufficient statistical power / B – Evidence from at least one large well-designed clinical trial with or without randomization, from cohort or case-control analytic studies, or well-designed meta analysis / C – evidence based on clinical experience, descriptive studies or reports of other in related fields
System 8: A,B,C,D (AGA,2)3 / A – homogeneous evidence from multiple well-designed, randomized (therapeutic) or cohort (descriptive) controlled trials each involving a number of participants to be of sufficient statistical power / B – evidence from at least 1 large well designed, clinical trial with or without randomization from cohort or case control analytic studies or well designed meta-analysis / C – evidence based on clinical experience, descriptive studies, or reports of expert committees / D - Recommendation is not rated (i.e. the recommendation is made but with no rating of any supporting quality of evidence)
System 9: I,II-1a,II-1b,II-2a,II-2b,II-2c,II-3,II,IV (AGA,2) / I - well designed RCT / II-1a – well designed controlled trials with pseudo-randomization
II-1b – well designed controlled trials with no randomization
II-2a – well designed cohort (prospective) study with concurrent controls
II-2b – well designed cohort (prospective) study with historical controls
II-2c – well designed cohort (retrospective) study with concurrent controls
II-3 – well designed case control (retrospective) study / III – large differences from comparison between times and/or places with and without intervention
IV – Opinions of respected authorities based on clinical experience; descriptive studies; reports of expert committees
1Grading system used by ACC/AHA/AASLD
2Grade system
3Modified version of grading system used by ACC/AHA/AASLD
Society / Guideline / Year
AGA / Capnography for Moderate Sedation / Feb-12
AGA / Stem Cell Research and Its Implications for Treating GI Cancers / Nov-08
AGA / Colorectal Cancer Screening and Surveillance for Early Detection / Mar-08
AGA / Endoscopy, Technology Assessment / Mar-08
ACG / Screening and Surveillance of the Early Detection ofColorectal Cancer And Adenomatous Polyps 2 / Mar-08
AGA / Obscure Gastrointestinal Bleeding, (revised) / Nov-07
AGA / CT Colonography Standards / Sep-07
AGA / Endoscopic Sedation / Aug-07
ACG / Management ofHelicobacter pylori Infection / Aug-07
AGA / Acute Pancreatitis / May-07
ACG / Esophageal Reflux Testing / Mar-07
AGA / Celiac Disease / Dec-06
AGA / Endoscopic Therapy for GERD / Oct-06
AGA / Gastric Subepithelial Masses / Jul-06
AGA / CT Colonography / Jul-06
AGA / GI Medication in Pregnancy / Jul-06
AGA / Colonoscopy Surveillance After Cancer Resection / May-06
AGA / Dyspepsia / Nov-05
AGA / Esophageal Carcinoma / May-05
AGA / Esophageal Manometry / Jan-05
AGA / Gastroparesis / Nov-04
ACG / Diagnosis and Management ofFecal Incontinence / Aug-04
AGA / Hemorrhoids / May-04
AGA / Sedation / Mar-04
AGA / Perianal Crohn’s Disease / Nov-03
Supplementary Table 2: Guidelines without quality of evidence graded n=56 continued
Society / Guideline / Year
AGA / Short Bowel Syndrome and Intestinal Transplantation / Apr-03
AGA / Colorectal Cancer Screening and Surveillance / Feb-03
AGA / Anal Fissure / Jan-03
AGA / Irritable Bowel Syndrome / Dec-02
AGA / Liver Chemistry Tests / Oct-02
AGA / Pancreatitis, Treatment of Pain in / Sep-02
ACG / Management ofPrimary Sclerosing Cholangitis / Mar-02
AGA / Office-based GI Endoscopy Services / Aug-01
AGA / Colorectal Cancer and Genetic Testing / Jul-01
ACG / Hepatic Encephalopathy / Jul-01
AGA / Celiac Sprue / May-01
AGA / Food Allergies / Mar-01
AGA / Nausea and Vomiting / Jan-01
AGA / Constipation / Dec-00
ACG / Diagnosis, Treatment and Surveillance for Patients with Colorectal Polyps / Nov-00
AGA / Colon Cancer, Impact of Dietary Fiber on / Jun-00
AGA / Intestinal Ischemia / May-00
ACG / Diagnosis and Management of Achalasia / Dec-99
ACG / Diagnosis and Management of Diverticular Diseaseof the Colon in Adults / Nov-99
AGA / Dysphagia /Benign Disorders of the Distal Esophagus / Jul-99
ACG / Liver Disease in the Pregnant Patient / Jul-99
AGA / Chronic Diarrhea / Jun-99
AGA / Anorectal Testing Techniques / Mar-99
ACG / Esophageal Cancer / Jan-99
AGA / Obesity / Sep-98
Supplementary Table 2: Guidelines without quality of evidence graded n=56 continued
Society / Guideline / Year
ACG / Management of the Adult Patient with Acute LowerGastrointestinal Bleeding / Aug-98
ACG / Acute InfectiousDiarrheain Adults / Nov-97
ACG / Diagnosis and Management ofC. difficile-Associated Diarrhea and Colitis / May-97
AGA / HIV Infection, Management of Malnutrition and Cachexia, Chronic Diarrhea, and Hepatobiliary Disease / Dec-96
ACG / Diagnosis and Treatment of Esophageal Diseases Associated with HIV Infection / Nov-96
AGA / Esophageal pH Recording / Jun-96
Abbreviations: ACG, American College of Gastroenterology, AGA, American Gastroenterological Association
Supplementary Table 3: Excluded evidence grading systemsSociety / ACG / AGA / AGA
Reference / Adapted from Cook D. et al. Chest 1992;102:3055 / USPSTF / NA
Number of guidelines / 1 / 2 / 1
Level of evidence / I Evidence from RCTs with low false positive rates (i.e. significant p values), adequate sample sizes (low likelihood of type II errors) and appropriate methodology (low likelihood of type I errors) / Grade A indicates that the certainty of evidence is high that the magnitude of net benefits is substantial. The USPSTF recommends providing the service for the specific population. / RCT establish efficacy - recommendation A – therapy should be routinely used
II Evidence from RCTs with high false positive rates, inadequate sample sizes or inappropriate methodology / Grade B indicates that the certainty of evidence is moderate that the magnitude of net benefits is either moderate or substantial, or that the certainty of evidence is high that the magnitude of net benefits is moderate. The USPSTF recommends providing the service for the specific population. / RCT but resource consideration limits its widespread applicability - recommendation B – therapy should probably be used
III Evidence from nonrandomized trials using a contemporaneous cohort of controls / Grade C indicates that the certainty of the evidence is either high or moderate that the magnitude of net benefits is small. The USPTF recommends against routinely providing the service for the specific population. There may be considerations that support providing the service in an individual patient. / No RCT trials available - recommendation C – no RCT evidence to assess whether or not therapy should be used
IV Evidence from nonrandomized trials using a historical cohort of controls / Grade D indicates that the certainty of the evidence is high or moderate that the magnitude of net benefits is either zero or negative. The USPSTF recommends against providing the service for the specific population. / RCT with at least 1 trial unable to establish efficacy - recommendation D – therapy probably should not be used
V Evidence from case series without controls / Grade I indicates that the evidence is insufficient to determine the relationship between benefits and harms (ie, net benefit). The USPSTF concludes that the current evidence is insufficient to assess the balance of benefits and harms of the service in the specific population. / RCT – recommendation E – therapy should not be used routinely
Abbreviations: ACG, American College of Gastroenterology, AGA, American Gastroenterological Association RCT, randomized control trial USPSTF, United States Preventive Services Task Force
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