The use of feasibility studies for stepped-wedge cluster randomised trials: a review of impact and scope

Background The stepped-wedge cluster randomised trial (SW-CRT) is a complex design for which many decisions must be made during the design stage, such as the required number and length of steps. Feasibility studies might help to inform these decisions and increase the likelihood of the main trial’s success. However, there is currently no guidance on how feasibility studies for SW-CRTs should be conducted. This review, the first in a series of related projects, aims to establish how often feasibility studies are being conducted for SW- CRTs and determine which feasibility issues are currently being investigated. Ultimately this work will lead to guidance on how feasibility studies in SW- CRTs should be conducted. Methods and analysis Searches for feasibility studies for SW- CRTs were conducted in Ovid MEDLINE, Scopus, and psycinfo. Relevant studies were identified via titles, abstracts and full-text retrievals according to pre-defined study inclusion criteria. Data were abstracted on the aims of these studies and how these studies were able to inform the main trial. In order to also identify unpublished feasibility studies for SW- CRTs, fully published SW- CRTs were identified from the most recent systematic reviews. The authors of these studies were contacted with the aim of determining whether any unpublished feasibility work was conducted prior to the main trial. In addition, the lead statisticians for registered UK clinical trials units were contacted to acquire information on feasibility work that is being undertaken by these units to inform SW- CRTs. Conclusion This review, which is pending final results, will determine how often feasibility studies are being used to inform SW- CRTs and identify which feasibility issues are being investigated. Any information that is gained on how these feasibility studies have informed the main trials, will allow us to gain an insight into how feasibility studies can benefit SW- CRTs. Future qualitative work will determine which aspects of feasibility studies are considered most useful and what barriers are commonly encountered when conducting a SW-CRT.