Objectives: To revise CQS-2/Criterion II, concerning allocation concealment appraisal for prospective, controlled, clinical therapy trials.
Methods: Meta-analyses of trials with inadequate allocation concealment will be tested for in-between trial heterogeneity (I2 > 0) due to imbalances in baseline variables. Meta-analyses with positive test results will be used as basis to infer criteria for adequate allocation concealment. The CQS-2/Criterion II will be reformulated in line with the findings. The revised appraisal tool will be specified as CQS-2B
Reporting: The final report will be made available online as preprint in one of the major preprint repositories and submitted to a peer-reviewed journal.