Individual trainings versus group trainings: Preliminary evaluation of peer recruitment through Respondent Driven Sampling of hidden populations of drug users in New York City

Respondent Driven Sampling (RDS) relies on successive waves of peer-recruitment and long referral chains to reduce bias in sampling hidden populations. To encourage participant peer-recruitment, researchers either discuss recruitment strategies one-on-one with participants or use a group session format. This analysis compared peer-recruitment among those individually trained vs. those receiving individual and group training. To achieve a final sample size of 1200, outreach workers initially recruited 48 seeds from disadvantaged, ethnographically mapped neighborhoods aged 18-40 who 1) injected heroin/crack/cocaine °Ü3 years or 2) used non-injection heroin/crack/cocaine °Ý1 year. Eligible participants were given three RDS coupons to recruit peers, received individual recruitment trainings (IRT) with recruiting tips, and were invited to attend group-facilitated RDS trainings (RDST). RDST stressed the importance of RDS, encouraged role-playing and allowed sharing of successful and unsuccessful recruitment techniques. Chi-square analysis was used to evaluate statistical significance. In the initial recruitment waves, median age was 33 (range: 18-40), 40% were Hispanic, 47% Black, 75% male, 27% IDU, 42% homeless, 38% attended RDST. RDST was significantly associated with continuous recruitment waves (OR=2.0, p 0.008) compared with IRT only. Additionally, younger participants were less likely to attend RDST (OR=5.59, p 0.005) and there were no differences by IDU or homeless status. These preliminary findings suggest that RDS may be challenging when studies have strict eligibility criteria and target younger drug users. Since RDST may improve peer-recruitment, strategies to motivate younger participants to attend RDST should be implemented to improve the efficiency of RDS when targeting extremely hidden drug-using populations.