Abstract
BACKGROUND: Successful trial recruitment depends on balancing initial interest with participants' commitment and eligibility. It is uncertain how different motivational advertisement themes affect recruitment of interested and eligible trial participants.
METHODS: The GoFresh trials examined how healthy groceries affect blood pressure among Black adults from Boston healthy food priority areas. Using Facebook's "A/B testing" feature, users 18 years and older in eligible ZIP codes were randomly shown one of four digital advertisement themes-science volunteerism, study incentives, blood pressure reduction, or wellness in the Black community-between November 2023 and December 2024. We tracked Facebook and website analytics by theme. 'Interest' was defined as submission of an online interest form. 'Commitment' as visit no-show rates, and 'Eligibility' as qualification following the in-person visit. The 'number needed to screen' was calculated as 1 divided by the proportion of inquiries who were eligible.
RESULTS: Advertisements reached 603,418 Facebook users and generated 32,168 clicks, 264 inquiries, 73 scheduled visits, and 23 eligible participants. The community theme generated the highest inquiry engagement rate (54%) but lower commitment (8 no-shows) and the highest number needed to screen (17). The blood pressure theme had the lowest inquiry engagement rate (32%) but yielded the highest commitment (2 no-shows) and the lowest number needed to screen (8).
CONCLUSION: Beyond generating study interest, motivational themes may select for participants with varying degrees of commitment and eligibility, which could affect the cost-effectiveness of recruitment and long-term retention. These findings have important implications for timely and representative recruitment for cardiovascular trials.
REGISTRATION: URL: https://clinicaltrials.gov/; Unique Identifier: NCT05121337 &NCT05393232.