Assessing the Success Rate and Costs of Common Recruitment Strategies for a Community-Based Environmental Health Study

Context: Recruitment is a vital component of public health research to produce generalizable findings and analytical power for subgroup differences in health outcomes. Recruitment strategies in population-based health studies vary widely with limited information on response rates and expected costs. Objectives: To evaluate recruitment strategies to better inform future recruitment planning and practices based on response rates, implementation costs, and demographics of enrolled participants. Design: We cross-sectionally examined recruitment data from the Colorado Study on Community Outcomes from Per- and polyfluoroalkyl Substances (PFAS) Exposure (CO SCOPE). Passive strategies included announcements and word-of-mouth referrals; active strategies included in-person outreach via door-to-door canvassing and/or tabling at community events, and phone or email contact to participants from a previous study. We calculated response rates per population reached by each strategy and estimated costs of materials and staff time. Setting and Participants: In 2021–2023, we recruited and enrolled participants from 4 communities in El Paso County, Colorado. This site was part of a national multisite study of exposure to per- and polyfluoroalkyl substances in drinking water and associated health effects. We enrolled 916 adult participants (92% of our goal). Results: Overall participant response rate across all strategies was 0.5%. Response rates were lowest after announcements (0.1%), and highest from direct contact with previous study participants (32.3%). In-person outreach accrued the greatest number of enrolled participants but also at the highest estimated cost ($242/enrolled participant). Word-of-mouth referrals recruited the greatest proportions of young adults (aged 18–34) and people with a high school education or less. Ultimately, the enrolled study population over-represented older adults, women, and non-Hispanic White people compared with the target communities. Conclusions: Recruitment strategies differed substantially in response rates and cost effectiveness. Word-of-mouth referrals and in-person outreach were most successful in recruiting diverse populations.