Appraising evidence

Abstract

Appraisal of the quality of evidence when performing an umbrella review remains an integral part of the process. However, specifi c recommendations for evaluating systematic review quality have not conveniently coalesced for those interested in performing umbrella reviews. In this chapter, we will coalesce and discuss the tools available to critically appraise systematic reviews when performing an umbrella review. While assessing individual study risk of bias is not a standard part of an umbrella review, understanding the tools used by the included systematic reviews for this step is important. Guidelines exist for reporting systematic reviews of both randomized controlled trials and observational studies. Methods for assessing quality of a systematic review and the strength of the evidence are well established. The expanding fi eld of network meta-analysis has also provided good practices to appraise reporting and quality of its reviews. Future guidance documents on performance of umbrella reviews should give careful consideration to providing recommendations for formal risk of bias assessment as part of the evidence appraisal process.