Assessment of recruitment and retention strategies in a birth cohort study evaluating asthma inception in early childhood

Defining factors important to successful subject recruitment and retention is essential for conducting birth cohort studies to evaluate childhood asthma. Childhood Origins of ASThma (COAST) I and II (birth to 3, 3–7 yrs respectively) began with 312 consented families (one parent with allergies, asthma, or both) of which 289 met inclusion/exclusion criteria. Recruitment efforts focused on developing systems with Obstetrics clinic and hospital providers as well as primary care practitioners throughout the community. The goal was to assure that support of or participation in the project required minimal effort. A satisfaction survey (administered at age 3) was developed to measure these results. The retention rate for COAST I and II were 97.2% and 94.5%, respectively. During COAST I, 99.1% of the visits were completed; venipunctures were done and nasal lavages performed 96.5% and 98.0% of the time, respectively, despite the participants eventually living in 17 states and 5 countries. Based on a satisfaction survey (N=144), factors influencing retention were: receipt of useful health information (96%), attention to family time schedules (91%), access to specialty care (91%), interactions with study coordinators (80%), and support from primary physician (45%). The difficult procedures (8%), visit process (7%), and complicated questionnaires (6%), were listed as areas needing improvement. Successful retention rates in birth cohort studies appear to be highly dependent on the formation of partnerships resulting in health care access and educational exchange. These partnerships facilitate the acceptance of multiple visits and invasive procedures that are critical to the generation of quality prospective data.