Title: Feasibility studies for Stepped-Wedge Cluster Randomised Trials, appraising and informing practice.
Funder: Department of Health and Social Care

Abstract: Background: In Stepped-Wedge Cluster Randomised Trials (SW-CRTs), clusters are randomised to switch from control to intervention at different time points. All clusters begin the trial in the control and move to the intervention at their switch time, until by the end of the trial all clusters will be receiving the intervention. SW-CRTs are increasingly being used more often, particularly to evaluate complex interventions that due to practical, financial or logistical constraints it may not be possible to evaluate using another design of trial. However, although SW-CRTs have many advantages they do have some disadvantages due to their increased complexity. The decisions made in designing these trials will determine how successful the trials are. If a trial is unsuccessful it will have wasted the money that was invested into it, as well as the time and commitment of the participants involved.The Medical Research Council recommends that trials of complex interventions should be preceded by feasibility work. In particular, the importance of feasibility studies for CRTs has been emphasised, since these trials require a large number of decisions to be made about their design and are usually larger and more expensive than individually randomised trials. Since these decisions and more need to be made for SW-CRTs it should therefore be even more important to establish feasibility before the trial goes ahead. However, there is currently no advice on the issues affecting the feasibility of a SW-CRT or how feasibility studies should be conducted to address these issues.Aims: This research will aim to provide guidance on the issues that should be considered when conducting a SW-CRT, and how these issues might be resolved using a feasibility study. This will be achieved by answering the following questions: How prevalent are feasibility studies for SW-CRTs? What issues affect the feasibility of SW-CRTs? How can feasibility studies address the issues faced by SW-CRTs? How is it recommended that the feasibility of a SW-CRT be established? Plan of investigation: These questions will be answered through a variety of methods. The first will be answered by reviewing published SW-CRTs and feasibility studies for SW-CRTs to identify trials for which feasibility studies were conducted and, by contacting the authors of these papers, establish the issues these feasibility studies aimed to investigate.The second will be addressed through a qualitative study using a questionnaire and series of interviews. Participants in this study will cover a wide range of involvement in SW-CRTs, from principal investigators, research administrators and trial statisticians, through to panel members for large funding bodies. These individuals will share their views and own experiences of issues that are encountered during SW-CRTs and those that there are concerns about potentially encountering.The third and fourth questions will be answered through an investigation into ways that these issues can be resolved and through the development of guidance for conducting feasibility work for SW-CRTs. Possible resolutions to these issues and how a feasibility study should be designed in order to achieve this will be explored using analytical methods and simulation studies. The guidance will collate the entirety of this research into a single document which will make researchers aware of issues that they may encounter when conducting a SW-CRT, and provide them with recommendations for how these issues can be overcome.The guidance developed through this research should improve the quality of SW-CRTs, reducing the number of SW-CRTs that are unsuccessful and making better use of the limited funding for trials and the valuable time and commitment of patients' to these trials.

Lay abstract: Background: In trials, participants, or groups of participants (such as patients from a particular hospital), are usually randomly assigned to receive either a new treatment or another treatment, such as standard care, for the duration of the trial. In a stepped-wedge cluster randomised trial (SW-CRT) groups of participants are randomly assigned to start the new treatment at different times instead. All groups begin the trial not receiving the new treatment and then switch to the new treatment when their time comes, until by the end of the trial all groups will be receiving the new treatment. There are many decisions that need to be made when planning a SW-CRT and these decisions will determine how successful the trial will be. A trial may be deemed unsuccessful, for example, if the roll-out of the new treatment does not go to plan or if the required number of participants is not recruited. An unsuccessful trial will have wasted the money that was invested into it, as well as the time and commitment of the participants involved. For these trials where many decisions must be made, it has been recommended that the issues affecting the potential success of the trial should be investigated before the trial starts. However, since the SW-CRT is a relatively new design of trial, not all of these issues are known, nor the best way to investigate and resolve these issues so that the trial may proceed successfully. Aims: This research aims to: (1) Find out how often researchers are investigating the potential issues of SW-CRTs before the trial starts. (2) Find out more about the experiences of those who have used SW-CRTs in their research, particularly any issues that they have faced which have impacted on the success of the trial. (3) Explore how these issues impact on the potential success of SW-CRTs and ways in which these issues can be resolved. (4) Produce guidance which will inform those who are planning on using a SW-CRT of the issues that they might face and how they can plan for them. Plan of investigation: I will search the literature for published SW-CRTs. The publications will be read to see if there is any mention of prior investigations taking place to check how likely the trial was to succeed. This information, if given, is unlikely to be in much depth and so the authors of the papers will be contacted to obtain more detail on the issues that were investigated. The issues identified by these authors will be used to help design a questionnaire which will be sent to researchers involved in SW-CRT to find out about their experiences of being involved in SW-CRTs and the issues that they encountered. This will include individuals involved in the planning and running of SW-CRTs, academics, funding panel members and those who advise researcher on trials. Some of these individuals will also be invited to take part in interviews, so that their experiences can be explored in more depth. Discussions with advisory groups comprising of patients, the public and trial design experts, will prioritise which issues are explored further. The impact of these issues on the success of SW-CRTs will be investigated and methods will be developed to help resolve these issues. Some of these methods might be similar to those used for other designs of trial, however, it is likely that some new methods will need to be developed to resolve issues that are specific to SW-CRTs. The findings of this research will be collated to form a guidance document for researchers, advising them on the issues that they are likely to face when conducting a SW-CRT and the steps that they can take to overcome these issues so that the trial can proceed successfully. The expert advisory panel and interviewees from earlier in this research will be consulted throughout the development of the guidance to ensure its relevance. To ensure the findings of this research are widely distributed, they will be presented at conferences, published in openly accessible journals and discussed at a dedicated workshop.

Research activity codes: 4.4 POPULATION SCREENING;8.4 RESEARCH DESIGN AND METHODOLOGIES (HEALTH SERVICES)
Health categories: GENERIC HEALTH RELEVANCE