SWAT 116: The effectiveness of an infographic to improve trial recruitment: a randomised study within a trial (SWAT)

Background Randomised controlled trial recruitment is challenging. Recruitment and informed consent processes require provision of a participant information sheet (PIS). Visual presentation of information, in the form of an infographic, is increasingly utilised, despite limited effectiveness evidence. This Study Within A Trial (SWAT) assessed if a PIS plus an infographic increases recruitment relative to PIS alone. Methods A two-arm cluster randomised SWAT (1:1 allocation ratio at the site level), embedded within the SWHSI-2 trial. The primary outcome was recruitment rate analysed via mixed effects logistic regression using minimisation factors as fixed effects and site as a random effect. Secondary outcomes were the proportion of participants screened but not recruited, retention rate, and cost. Results All 29 SWHSI-2 sites were randomised to the SWAT (14 intervention; 15 control). Following SWAT implementation, 1634 patients were screened, with 1068 patients eligible (PIS plus infographic: 662/1008 [65.7%]; PIS only: 406/626 [64.9%]) and 585 randomised into the SWHSI-2 trial (PIS plus infographic: 342/662 [51.7%]; PIS only: 243/406 [59.9%]; (OR 0.61, 95% CI 0.23 to 1.62, p=0.32). More patients were screened but not randomised in the intervention group compared to the control group (n=666, 66.1% vs n=383, 61.2%). Meta-analysis of two studies found the infographic intervention reduced participant recruitment (OR = 0.61, 95% CI 0.31 to 1.23). Conclusion Two SWAT replications have found that including an infographic alongside a PIS does not increase participant recruitment, but estimates were imprecise. Replications in other populations and exploration of infographic content and design remain warranted. Key Words SWAT; study within a trial; retention methods; embedded randomised controlled trial