Common concerns about the feasibility of stepped-wedge cluster randomised trials and issues encountered during trials of this design: findings of an online questionnaire

ntroduction:Stepped-wedge cluster randomised trials (SW-CRTs) area complex design with features that may increase the likelihood of the trial encountering issues that may impact its feasibility. The aimof this work was to determine the common issues affecting the feasi-bility of SW-CRTs.Methods:An online questionnaire, consisting of closed questionsand free-text responses, asked respondents about their involve-ment in SW-CRTs, concerns about the feasibility of the trial andany problems encountered. Participants were also asked aboutany concerns they had about SW-CRTs in general. Potential par-ticipants were identified from the authors of published SW-CRTs,list of delegates at conferences about SW-CRTs, panel memberpages of funders’websites, and the websites of clinical trialsunits and the Research Design Service. Recipients were encour-aged to forward their email invitation onto anyone that might beinterested in participating. Open invitations were posted on Twit-ter. A descriptive analysis was conducted.Results:Email invitations were sent to 403 individuals, 154(38%)responded, mostly trialists (66%) and funding panel members (16%).Most participants had been involved with a SW-CRT (82%) and hadconcerns about some aspect of the design (94%). Some of the mostcommon concerns related to the staggered implementation: not hav-ing all clusters ready when the trial starts; clusters not willing or ableto start the intervention when randomised to; when to inform clus-ters of when they’ll start the intervention; and retention of the lastclusters to start the intervention.Discussion:There are features of the SW-CRT design which have thepotential to impact the feasibility of the trial. In particular, the stag-gered implementation of the intervention, although often one of themain reasons for choosing this design, can cause problems. The add-itional challenges of staggering the implementation of the interven-tion need to be weighed against the potential benefits.