A Systematic Review of Stepped Wedge Cluster Randomized Trials in High Impact Journals: Assessing the Design, Rationale, and Analysis

Abstract
Objective
Stepped wedge cluster randomized trials (SW-CRTs) are an appealing study design because they enable sequential roll out of an intervention across clusters, bringing logistical advantages. This review aimed to evaluate the design rationale, design features, stepped wedge diagram, and analytical approaches of SW-CRTs published in high-impact medical journals from 2020 to 2023, focusing particularly on adherence to key guidelines from the CONSORT extension to SW-CRTs.
Study Design and Setting
We conducted searches across PubMed and Cochrane Central Registry of Controlled Trials (CENTRAL) databases for SW-CRTs published between January 2020 and December 2023 in eight high-impact journals. Eligibility criteria included peer-reviewed publications of randomised SW-CRTs involving human participants, published in English.
Results
Of the 23 SW-CRTs included in the review, 70% had "stepped wedge" explicitly mentioned in their titles. Most studies (96%) included a stepped wedge diagram, but only 65% of these diagrams clearly communicated the duration of each time period. There was considerable variability in design features, including number of sequences (median of 7, range 3-20) and clusters (median of 15, range 9-19). The majority of trials (78%) provided robust justifications for selecting SW-CRT design, for example citing practical or logistical constraints. However, 22% of the studies offered less convincing rationales. Generalized linear mixed models (GLMMs) were the most frequent analysis method employed.
Conclusion
Our review has highlighted areas for improvement in the presentation of SW-CRTs, particularly in clearly indicating the duration of time periods within diagrams and providing robust justifications for selecting a SW-CRT design.