Cochrane Risk of Bias Tool
This tool helps assess how reliable a clinical trial is by checking for flaws in its design, conduct, and reporting that might distort the results.
At a glance
Use when
Assessing the methodological quality of randomized controlled trials in systematic reviews.
Avoid when
Evaluating non-randomized studies or when detailed trial information is unavailable.
Inputs
Full trial reports, protocols, and supplementary materials for randomized trials.
Outputs
Risk of bias judgments across six domains, often visualized in summary and graph format.
How it works
The Cochrane Risk of Bias Tool evaluates seven key domains—random sequence generation, allocation concealment, blinding of participants and personnel, blinding of outcome assessment, incomplete outcome data, selective reporting, and other biases—to determine the risk of bias in randomized controlled trials. Each domain is judged as low, high, or unclear risk of bias to inform the credibility of trial findings.
- HTA domains
- Clinical Effectiveness, Safety
- Categories
- Data Quality Assessment
- Assumptions
- Bias can systematically distort effect estimates; domain-based assessment improves consistency and transparency in evaluating trial quality.
- Strengths
- Standardized and systematic approach to bias assessment,Widely adopted in systematic reviews and meta-analyses,Improves transparency and reproducibility of quality appraisal
- Limitations
- Subjective judgments may vary between reviewers,Limited guidance on how to combine domain-level judgments into an overall risk of bias score,Designed for randomized trials only
- Also known as
- RoB 1, Cochrane Risk of Bias Tool version 1, Cochrane Collaboration's risk of bias tool
Questions this answers
- › Is the trial's design likely to produce unbiased results?
- › Were participants assigned randomly and was allocation concealed?
- › Were participants, personnel, and outcome assessors blinded?
- › Were all planned outcomes reported completely?
- › Were there missing data and were they handled appropriately?
- › Are there other sources of bias not covered in the main domains?
References & sources
Related methods
Beta record. Based on the original catalogue summary; primary-source enrichment pending.