Accessibility statement

IMPLEMENT SWATs: Using IMPLEMENTation science and Studies Within A Trial to improve evidence-informed participant recruitment and retention in randomised controlled trials

What are the aims of this research programme?

Our broad aim is to promote the use of research evidence for recruiting and following up with participants in randomised trials testing health treatments.

Why are we doing this study?

Trials are the best way to test how effective health treatments are. However, about half of all trials fail to recruit enough participants, and many participants drop out once they are recruited. These problems with recruitment and retention cause huge amounts of research waste that has been described as a scandal. Poor recruitment and retention have a human cost, too. A study of a COVID-19 trial found that if it had recruited 50% of all suitable patients instead of just 15% (typical for trials of its type), nearly 3000 more lives could have been saved in the UK alone, from patients receiving the effective treatment earlier.

A good way to test recruitment and retention strategies is to use a ‘Study Within A Trial’ (SWAT), which is a piece of research built into a ‘host’ trial. But not many SWATs have been done, and there are almost no effective and cost-effective strategies for recruiting and retaining participants in trials.

In the MRC-funded PROMETHEUS programme, we successfully showed that a recruitment or retention strategy can be tested across different host trials and patient groups at the same time to significantly speed up and increase the evidence base. However, researchers tend to not use evidence when planning recruitment and retention. This may be because there are no guidelines to support the use of evidence-based recruitment and retention strategies, so that the strategies that are effective are used, and those that are not effective are avoided.

What methods are we using?

We will use ‘implementation science’, which is the study of methods to promote the use of research findings. IMPLEMENT SWATs is a multi-methods programme and consists of five interlinked work packages:

  1. Work package one will identify and prioritise strategies that are used to recruit and retain participants by doing a review of trials published in the UK and elsewhere.
  2. Work package two will test the highest priority recruitment and retention strategies to see if they are effective and cost-effective, by doing several SWATs at the same time for each strategy.
  3. Work package three will bring together all the evidence on the effectiveness and cost-effectiveness of recruitment and retention strategies to develop guidelines for evidence-based recruitment and retention.
  4. Work package four will develop and apply an implementation strategy to support members of the trial community to use the recruitment and retention guidelines.
  5. Work package five will use multiple methods to test the effectiveness and cost-effectiveness of the implementation strategy and will tentatively explore whether using the guideline is associated with better recruitment and retention.

Taking Part

We are funded to collaborate with host trial teams to undertake coordinated SWATs of monetary incentives. If you are interested in being part of a coordinated SWAT, you can find further information about taking part below.

Implement SWATs Host trial information leaflet (PDF , 336kb)

Privacy Notice: How we use your research data


Funder: This project is funded by the NIHR (Advanced Fellowship, reference: NIHR302256). The views expressed are those of the authors and not necessarily those of the NIHR or the Department of Health and Social Care.
Sponsor: University of York
Start Date: July 2022
End Date: June 2032

Contact Us

To contact the IMPLEMENT SWATs team, please email: Alternatively, you can contact individual team members using the contact details below:


YTU team

External collaborators