Systematic review of the use of stepped wedge cluster randomized trials
Seminar Room 2, Newton Institute Gatehouse
Background In a stepped wedge cluster randomized controlled trial, clusters are randomly allocated to the order in which they will receive the intervention, with one cluster receiving the intervention at the beginning of each study period (step). Therefore by the end of the recruitment period all clusters have received the intervention, but the number of periods in the ‘control’ and ‘intervention’ sections of the wedge will vary across clusters.
Objective To describe the application of the stepped wedge cluster randomized controlled trial design using a systematic review.
Study Design and Setting We searched MEDLINE, EMBASE, PSYCINFO, HMIC, CINAHL, Cochrane Library, Web of Knowledge and Current Controlled Trials Register for articles published up to January 2010. Stepped wedge cluster randomized controlled trials from all fields of research were included. Two authors independently reviewed and extracted data from the studies.
Results Twenty five studies were included in the review. Motivations for using the design included ethical, logistical, financial, social and political acceptability and methodological reasons. Most studies were evaluating an intervention during routine implementation. For most of the included studies there was also a belief or empirical evidence suggesting that the intervention would do more good than harm. There was variation in data analysis methods and insufficient quality of reporting.
Conclusions The stepped wedge cluster randomized controlled trial design has been mainly used for evaluating interventions during routine implementation, particularly for interventions that have been shown to be effective in more controlled research settings, or where there is lack of evidence of effectiveness but there is a strong belief that the intervention will do more good than harm. There is need for consistent data analysis and reporting.