A ‘Risk of bias’ table is an optional, although strongly recommended, extension of the ‘Characteristics of included studies’ table. The standard ‘Risk of bias’ table includes an assessment for allocation concealment and the authors can add further items. For each item, the table provides a description of what was reported to have happened in the study and a subjective judgement regarding protection from bias (‘Yes’ for a low risk of bias, ‘No’ for a high risk of bias; ‘Unclear’ otherwise).