Cost-effectiveness analysis of recruitment strategies in a large diabetes prevention trial conducted across two sites in Sydney, Australia.

ABSTRACT

BACKGROUND: Diabetes prevention trials require large samples and community-based recruitment, which can be protracted and expensive. We analysed the cost-effectiveness of recruitment strategies used in a randomised placebo-controlled supplement trial in adults with prediabetes and overweight or obesity conducted in Sydney, Australia. METHODS: Recruitment strategies included advertising through local radio stations and newspapers, television news coverage, online advertising and editorials, advertising in and referral from primary care settings, university- and hospital-based advertising, and attending or hosting local events. For each strategy, the number of expressions of interest, screenings booked, and randomised participants were collated. The percentage contribution from each strategy, overall cost, and cost per participant were calculated. RESULTS: Of 4498 expressions of interest, 551 (12%) were eligible for onsite screening and 401 (9%) were randomised. Recruitment costs totalled AU$218,501, averaging AU$545 per participant. The recruitment strategy was recorded for 49% who expressed interest in the trial, and for 75% randomised into the trial. From these data, advertising on local radio stations was the most cost-effective strategy, contributing 46% of participants at AU$286 per participant, then advertising in and referral from primary care settings (57 participants [19%], AU$1438 per participant). The least cost-effective strategy was television news coverage, which was not targeted to the Sydney-based audience, contributing only six participants (AU$10,000 per participant). CONCLUSION: Radio advertising and recruitment through healthcare were the most effective recruitment strategies in this trial. Recruitment strategies should be location-specific and appropriate for the target population, prioritising low-effort high-yield strategies. Trial investigators should seek opportunities for free advertising.