RoB 2

RoB 2 (Risk of Bias 2) is a tool that is used to assess the bias risk in randomized controlled trials (RCTs) and non-randomized studies. The tool was developed by the Cochrane Collaboration and is widely used in systematic reviews and meta-analyses to evaluate the quality of evidence.

RoB 2 assesses five domains of bias:

Bias arising from the randomization process

Bias due to deviations from intended interventions

Bias due to missing outcome data

Bias in the measurement of the outcome Bias in the selection of the reported result Each domain is assessed using a set of signaling questions that help to identify potential sources of bias. For example, the first domain, bias arising from the randomization process, include questions such as whether the allocation sequence was adequately randomized, whether the allocation was concealed, and whether there were any baseline imbalances between the intervention and control groups.

After completing the assessments, the overall risk of bias for each study is determined based on the responses to the signaling questions. The risk of bias can be rated as low, with some concerns, or high for each domain, and an overall rating is given based on the most serious risk of bias identified in any domain.

RoB 2 is considered to be a comprehensive and transparent tool for assessing the risk of bias in studies and is recommended by many organizations and guidelines, including the Cochrane Handbook for Systematic Reviews of Interventions.