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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