Stepped wedge cluster randomized controlled trial designs: a review of reporting quality and design features

Abstract

Background: The stepped wedge (SW) cluster randomized controlled trial (CRCT) design is being used with increasing frequency. However, there is limited published research on the quality of reporting of SW-CRCTs. We address this issue by conducting a literature review.

Methods: Medline, Ovid, Web of Knowledge, the Cochrane Library, PsycINFO, the ISRCTN registry, and ClinicalTrials.gov were searched to identify investigations employing the SW-CRCT design up to February 2015. For each included completed study, information was extracted on a selection of criteria, based on the CONSORT extension to CRCTs, to assess the quality of reporting.

Results: A total of 123 studies were included in our review, of which 39 were completed trial reports. The standard of reporting of SW-CRCTs varied in quality. The percentage of trials reporting each criterion varied to as low as 15.4%, with a median of 66.7%.

Conclusions: There is much room for improvement in the quality of reporting of SW-CRCTs. This is consistent with recent findings for CRCTs. A CONSORT extension for SW-CRCTs is warranted to standardize the reporting of SW-CRCTs.

Keywords: Cluster randomized controlled trial; Reporting quality; Review; Stepped wedge.

Fig. 1

Flow diagram of records through the literature review. 123 studies were ultimately included in our review. PG-CRCT, parallel group clustered randomized controlled trial; SW, stepped wedge

Fig. 2

Use of the SW-CRCT design. The cumulative frequency of the designs use over time is displayed, according to the included reports and other records (trial registrations, protocols, conference reports)

Fig. 3

Design characteristics of SW-CRCTs. (a) Number of clusters and (b) time period between steps of the included studies (where clear) is depicted, according to whether the study record is either a completed report or other record type (trial registrations, protocols, conference reports). For completed reports, the final true figures are used; for the other records, the planned amounts are employed. For the box plot of the time periods between steps, 1 month was treated as 4 weeks and 1 year as 52 weeks. Notches are used to display the 95% confidence interval for the median, and the boxplot widths are proportional to the square root of the number of records on which they are based

Fig. 4

Quality of reporting over time. The percentage of the criteria that each study met against its publication year is depicted, according to (a) all considered criteria, (b) the subset listed on the CONSORT extension to CRCTs, and (c) the 10 criteria chosen as key. A Loess smoother is present on each graph to indicate time patterns, along with its 95% confidence interval