The revised JBI critical appraisal tool for the assessment of risk of bias for cohort studies

Abstract

Cohort studies are a robust analytical observational study design that explore the difference between two different cohorts on an outcome, differentiated by their exposure status. Despite being observational in nature, they are often included in systematic reviews of effectiveness, particularly when randomized controlled trials are limited or not feasible. Like all studies included in a systematic review, cohort studies must undergo a critical appraisal process to assess the extent to which a study has considered potential bias in its design, conduct, or analysis. Critical appraisal tools facilitate this evaluation. This paper introduces the revised critical appraisal tool for cohort studies, completed by the JBI Effectiveness Methodology Group (EMG), who are currently revising the suite of JBI critical appraisal tools for quantitative study designs. The revised tool responds to updates in methodological guidance from the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) Working Group and reporting guidance from PRISMA 2020, providing a robust framework for evaluating risk of bias in a cohort study. Transparent and rigorous assessment using this tool will assist reviewers in understanding the validity and relevance of the results and conclusions drawn from a systematic review that includes cohort studies. This may contribute to better evidence-based decision-making in health care. This paper discusses the key changes made to the tool, justifications for these changes, and provides practical guidance on how this tool should be interpreted and applied by systematic reviewers.