Realist Trials and Systematic Reviews: Rigorous, Useful Evidence to Inform Health Policy

Book Title: Realist Trials and Systematic Reviews: Rigorous, Useful Evidence to Inform Health Policy

Authors: Chris Bonell, G.J. Melendez-Torres, Emily Warren

Publication Details: Cambridge University Press, 2024, 124 pp, $49.99 paperback

Realist Trials and Systematic Reviews describes a unique approach to the evaluation of complex interventions—the kind often used in family medicine or public health research. The book describes what a realist trial and a realist systematic review are and compares them to realist evaluations and realist reviews on the more qualitative end of the evaluation spectrum and randomized control trials and systematic reviews on the more quantitative side of the evaluation spectrum. Realist trials and realist systematic reviews are essentially a combination of both methods of evaluation with both qualitative and quantitative evaluation. An example of a realist trial would be a study looking at case management for chronic obstructive pulmonary disease. In a realist trial, the researchers would examine not only whether the intervention reduced hospital admissions, but how it worked, for whom, and in what settings. The authors are professors in the London School of Hygiene and Tropical Medicine with expertise in realist trials. They use one of their realist trials as a case study to describe the underlying theory for realist trials as well as the details of the methodology for these types of trials.

The book begins by describing how randomized control trials and systematic reviews fail to fully evaluate complex interventions common in public health. The authors next describe the theory used in realist evaluation and how that answers some of the issues that evaluations through randomized control trials struggle to address. The theory used in realist evaluation is based on the generative theory of causation; instead of asking, “Does it work?”, realist evaluation asks, “What about this program works and for whom and in what circumstances?” Researchers use the context-mechanism-outcome model as the primary analytic tool. Context refers to the conditions in which the program is implemented; mechanism refers to the underlying processes or responses triggered; and outcomes refers to the patterns of effects involved. Next, the authors describe how realist evaluations and realist reviews are not able to fully evaluate a complex intervention. Finally, they describe what a realist trial and realist systematic review are and how they can more fully address the evaluation of a complex intervention. The organization does make sense and the argument made for using realist trials is compelling.

This book is a good introduction to what a realist trial is, but the average family medicine researcher probably would need to have more detailed explanation in order to potentially use this methodology for their own intervention evaluations. While the book was useful for seeing this methodology applied in the authors’ own research, what this would look like in other contexts with other types of interventions is unclear. Also unclear is how this approach compares to other approaches to mixed-methods research, which was not directly discussed in this book. For mixed methods researchers to better understand more explicitly how mixed methodology and realist trial methodology overlap could be useful.

This book is primarily written for researchers engaged in complex interventions often seen in public health and family medicine. The book describes a new methodology for evaluation using both qualitative and quantitative research. It is introductory, so readers would not be equipped to perform their own realist trials after reading this book; but the book does provide a nice primer for someone who is looking for a new approach to understanding complex evaluations.