The revised JBI critical appraisal tool for the assessment of risk of bias for quasi-experimental studies

Systematic reviews of effectiveness offer a rigorous synthesis of the best evidence available regarding the effects of interventions or treatments. Randomized controlled trials are considered the optimal study design for evaluating the effectiveness of interventions and are the ideal study design for inclusion in a systematic review of effectiveness. In the absence of randomized controlled trials, quasi-experimental studies may be relied on to provide information on treatment or intervention effectiveness. However, such studies are subject to unique considerations regarding their internal validity and, consequently, the assessment of the risk of bias of these studies needs to consider these features of design and conduct. The JBI Effectiveness Methodology Group has recently commenced updating the suite of JBI critical appraisal tools for quantitative study designs to align with the latest advancements in risk of bias assessment. This paper presents the revised critical appraisal tool for risk of bias assessment of quasi-experimental studies; offers practical guidance for its use; provides examples for interpreting the results of risk of bias assessment; and discusses major changes from the previous version, along with the justifications for those changes.