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Table 5 Use of risk of bias and risk of bias domains in the Cochrane and non-Cochrane reviews that applied the Cochrane risk of bias tool for randomized clinical trials

From: Evaluation of the Cochrane tool for assessing risk of bias in randomized clinical trials: overview of published comments and analysis of user practice in Cochrane and non-Cochrane reviews

Use of risk of bias and risk of bias domains 100 Cochrane reviews (100 %) 31 non-Cochrane reviews (100 %)f P value*
Use of risk of bias    
 Summarises risk of bias on an outcome levela 12 (12 %) 2 (6 %) 0.73
 Unclear what level risk of bias was summarised onb 88 (88 %) 29 (94 %) 0.88
Use of risk of bias standardc domains    
 Review uses the 2011 tool version 100 (100 %) 26 (84 %) 0.65
 Review uses all standardc domains 59 (59 %) 16 (52 %) 0.73
  -Sequence generation 100 (100 %) 30 (97 %) 1.00
  -Allocation concealment 100 (100 %) 30 (97 %) 1.00
  -Blinding of patients and care providers 62 (62 %) 21 (68 %) 0.87
  -Blinding of outcome assessors 65 (65 %) 20 (65 %) 1.00
  -Incomplete outcome data 99 (99 %) 29 (94 %) 0.88
  -Selective reporting 87 (87 %) 25 (81 %) 0.88
Merging and splitting of standardc domains    
 Review merges two standardc domains 37 (37 %) 8 (26 %) 0.53
  -Merges risk of bias domains on an outcome leveld 6 of 37 (16 %) 0 of 8 (0 %) 0.57
  -Does not merge risk of bias domains on an outcome level 31 of 37 (84 %) 8 of 8 (100 %) 0.79
 Review splits a standardc domain into two or more domainse 18 (18 %) 7 (23 %) 0.62
  1. *P values were calculated with Fisher’s two-tailed exact test
  2. aOne or more domains were separately assessed for more than one outcome or groups of outcomes (i.e. subjective versus objective outcomes)
  3. bReview has a singular risk of bias assessment despite more than one outcome included in the review. No review based its risk of bias assessment on a singular or primary outcome
  4. cThe six standard domains (not including the “other bias” domain) included in the Cochrane risk of bias tool for randomized clinical trials (i.e. the tool)
  5. di.e. merges blinding of patients and care providers with blinding of outcome assessors into one blinding domain and evaluates blinding for subjective/objective or explicit (≥2) outcomes.
  6. ei.e. splits blinding of patients and care providers into blinding of personnel and blinding of patients or splits incomplete outcome data into assessment of intention-to-treat and assessment of dropouts.
  7. f31 of 100 non-Cochrane reviews used the Cochrane risk of bias tool for randomized clinical trials (i.e. the tool) and were compared to the 100 Cochrane reviews that used the tool for randomized clinical trials