Grand rounds in methodology: when are realist reviews useful, and what does a 'good' realist review look like?

Research in the quality and safety field often necessitates an approach that supports the development of an in-depth understanding of how a complex phenomenon occurs, or how an intervention works. Realist review is an increasingly popular form of evidence synthesis that provides a theory-driven, interpretive approach to secondary research. Realist reviews offer quality and safety researchers the opportunity to draw on diverse types of evidence to develop explanatory theory about how, when and for whom interventions 'work' or outcomes occur. The approach is flexible, iterative and practical, typically drawing on the experience of policymakers, practitioners and patients throughout the review. With the increasing use of realist reviews, some common misconceptions about the approach have become evident in the literature. This paper introduces what is involved when planning and conducting a realist review, and where the approach can offer most value, as well as outlining common challenges that researchers may face when adopting the approach, and recommended solutions. Our aim is to support researchers who are considering conducting a realist review to understand the key principles and concepts involved, and how they can go about producing high-quality work.