Objectives: The objective of the study was to develop and validate an adequate tool to evaluate the risk of bias of randomized controlled trials, observational studies, and systematic reviews assessing drug adverse events.
Study design and setting: We developed a structured risk of bias checklist applicable to randomized trials, cohort, case-control and nested case-control studies, and systematic reviews focusing on drug safety. Face and content validity was judged by three experienced reviewers. Interrater and intrarater reliability were determined using 20 randomly selected studies, assessed by three other independent reviewers including one performing a 3-week retest.
Results: The developed checklist examines eight domains: study design and objectives, selection bias, attrition, adverse events information bias, other information bias, statistical methods to control confounding, other statistical methods, and conflicts of interest. The total number of questions varied from 10 to 32 depending on the study design. Interrater and intrarater agreements were fair with Kendall's W of 0.70 and 0.74, respectively. Median time to complete the checklist was 8.5 minutes.
Conclusion: The developed checklist showed face and content validity and acceptable reliability to assess the risk of bias for studies analyzing drug adverse events. Hence, it might be considered as a novel useful tool for systematic reviews and meta-analyses focusing on drug safety.
Keywords: Adverse drug events; Checklist; Meta-analysis; Risk of bias; Study quality; Systematic review.
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