OBJECTIVES: The Ottawa Statement on the Ethical Design and Conduct of Cluster Randomized Trials (CRTs), published in 2012, is the first and remains the only international ethics guidance document specific to CRTs. However, the stepped-wedge CRT design raises complex ethical issues for which guidance may be lacking. The overarching objective of this review is to inform the forthcoming update of the Ottawa Statement; specific objectives are to characterize the types of interventions and data collection procedures in stepped-wedge CRTs (SW-CRTs), and to examine adherence to key ethical design, conduct, and reporting recommendations.
STUDY DESIGN AND SETTING: Primary reports of SW-CRTs evaluating health interventions published 2016-2022 in English were reviewed. Two reviewers extracted data from each trial independently; discrepancies were resolved through consensus.
RESULTS: Among 160 SW-CRTs, most evaluated multilevel interventions (78, 49%), and uncommonly involved therapeutic patient interventions (19, 12%). Few (10, 6%) exclusively used routinely collected data sources for outcome assessment. Sixty-four trials (40%) provided explicit justifications for using cluster randomization and the stepped-wedge design. Most (157, 98%) included a statement about research ethics committee (REC) review, of which 148 (94%) reported approval. A statement about consent was reported in 145 (91%), with 113 (78%) pertaining to patients only, 10 (7%) to health-care providers only, and 22 (15%) to both. Among 135 trials reporting on patient consent, consent was not obtained in 55 (41%). Justifications for not obtaining consent were provided in 42 (76%).
CONCLUSION: The updated Ottawa Statement should provide guidance about when people should be considered research participants and when their consent is required, justifications for using a stepped-wedge design, the need for REC review, and the burden of data collection procedures in SW-CRTs.
PLAIN LANGUAGE SUMMARY: We reviewed 160 SW-CRTs published between 2016 and 2022. These trials often evaluate multifaceted interventions delivered at the cluster or professional level rather than individual level, and most had to rely on at least some form of primary data collection. Although almost all SW-CRTs reported ethics review, fewer than half explained why they used the SW-CRT design, and a substantial minority did not include a statement about whether participant informed consent was obtained. Rarely did consent statement pertain to health-care providers; most statements pertained to patients. Among the SW-CRTs that had consent statements pertaining to patients, almost half reported not obtaining or waiving consent from them, and many of these did not report clear reasons for this. Our findings highlight the need for clearer guidance in the forthcoming update to the Ottawa Statement on the Ethical Design and Conduct of CRTs.