Domain

Support for judgement

Review authors’ judgement

Selection bias

Random sequence generation

Describe the method used to generate the allocation sequence in sufficient detail to allow an assessment of whether it should produce comparable groups.

Selection bias (biased allocation to interventions) due to inadequate generation of a randomised sequence.

Allocation concealment

Describe the method used to conceal the allocation sequence in sufficient detail to determine whether intervention allocations could have been foreseen in advance of, or during, enrolment.

Selection bias (biased allocation to interventions) due to inadequate concealment of allocations prior to assignment.

Performance bias

Blinding of participants and personnel

Assessments should be made for each main outcome (or class of outcomes). 

Describe all measures used, if any, to blind study participants and personnel from knowledge of which intervention a participant received. Provide any information relating to whether the intended blinding was effective.

Performance bias due to knowledge of the allocated interventions by participants and personnel during the study.

Detection bias

Blinding of outcome assessment

Assessments should be made for each main outcome (or class of outcomes).

Describe all measures used, if any, to blind outcome assessors from knowledge of which intervention a participant received. Provide any information relating to whether the intended blinding was effective.

Detection bias due to knowledge of the allocated interventions by outcome assessors.

Attrition bias

Incomplete outcome dataAssessments should be made for each main outcome (or class of outcomes). 

Describe the completeness of outcome data for each main outcome, including attrition and exclusions from the analysis. State whether attrition and exclusions were reported, the numbers in each intervention group (compared with total randomised participants), reasons for attrition/exclusions where reported, and any re‐inclusions in analyses performed by the review authors.

Attrition bias due to amount, nature or handling of incomplete outcome data.

Reporting bias

Selective reporting

State how the possibility of selective outcome reporting was examined by the review authors, and what was found.

Reporting bias due to selective outcome reporting.

Other bias

Other sources of bias

State any important concerns about bias not addressed in the other domains in the tool.

If particular questions/entries were pre‐specified in the review’s protocol, responses should be provided for each question/entry.

Bias due to problems not covered elsewhere in the table.