Using X, Facebook QR codes to optimise recruitment to a feasibility trial Enhancing Men’s Awareness of Testicular Diseases (E-MAT) in a cluster randomised Study Within A Trial (SWAT): Lessons learned. [version 1; peer review: awaiting peer review]

Background Eight out of ten adults use social media, yet its efficacy in recruitment in clinical trials remains under-explored. The purpose of this SWAT was to determine which recruitment method, X, Facebook or QR code via posters, was more efficient and cost effective for recruiting participants to the host trial. Methods A cluster randomised cross-over design evaluated three recruitment strategies, X, Facebook and QR code. Seven Gaelic Athletic Association (GAA) clubs were randomised to receive either X, Facebook, or QR code. The seven clubs were re-randomised twice more, two weeks apart. There were two primary outcomes: 1. proportion of participants who consent to participate, relative to the number of players contacted; and 2. proportion of participants who consent to participate, relative to the number of players who clicked the link to register their interest. Results Fifty participants were randomised to three recruitment methods, and 47 were retained in the host trial. Participants mainly heard about the study through friends, with some engagement via social media platforms Facebook and X, and little to no engagement with the QR code. Primary outcomes were hindered by the inability to disaggregate data by GAA club. Economic outcomes revealed QR code as the costliest strategy, and while X was cheaper than Facebook in terms of the number of clicks, Facebook demonstrated better recruitment and retention and thus reduced the costs per participant. Conclusions While the inability to disaggregate data by club was a limitation, the study revealed that Facebook outperformed X and QR codes in terms of recruitment and participant retention and was thus considered to be more cost effective. The findings emphasise the importance of considering engagement patterns and cost-effectiveness in designing recruitment strategies for clinical trials, especially within the dynamic landscape of social media use.