ROBIS: A new tool to assess risk of bias in systematic reviews was developed

Systematic reviews are generally considered to provide the most reliable form of evidence to guide decision makers. Here we describe ROBIS, a new tool for assessing the risk of bias in systematic reviews (rather than in primary studies). ROBIS has been developed using rigorous methodology and is currently aimed at four broad categories of reviews mainly within healthcare settings: interventions, diagnosis, prognosis and aetiology. The target audience of ROBIS is primarily guideline developers, authors of overviews of systematic reviews ("reviews of reviews") and review authors who might want to assess or avoid risk of bias in their reviews. The tool is completed in 3 phases: (1) assess relevance (optional), (2) identify concerns with the review process and (3) judge risk of bias. Phase 2 covers four domains through which bias may be introduced into a systematic review: study eligibility criteria; identification and selection of studies; data collection and study appraisal; and synthesis and findings. Phase 3 assesses the overall risk of bias in the interpretation of review findings and whether this considered limitations identified in any of the Phase 2 domains. Signalling questions are included to help judge concerns with the review process (Phase 2) and the overall risk of bias in the review (Phase 3); these questions flag aspects of review design related to the potential for bias and aim to help assessors judge risk of bias in the review process, results and conclusions.