Retention factors for participants of an inner-city community-based asthma intervention study.

Participant retention is a significant challenge for asthma field trials examining the effectiveness of prevention strategies in inner-city communities. Here, the authors evaluate factors associated with participant retention in an inner-city, pediatric, asthma intervention trial in Atlanta, Georgia, during 1998-2000. Demographic, clinical, residential, personnel, and logistical variables were analyzed by chi-square and Wilcoxon rank sum nonparametric tests to compare children who remained in the asthma study with those who were dropped. Of the 489 participants, 486 (99%) were African-American, 467 (96%) were non-Hispanic, 281 (57%) were male, and 142 (29%) remained in the study. Of the 347 dropouts, 149 (43%) were dropped because of missing study visits. Retention rates were significantly higher (P<.05) for participants enrolled in the second year of the study (2nd yr=43%, 1st yr=19%), for those who lived longer at the same residence (> or = 3 yrs=36%, 2-3 yrs=26%, 1-<2 yr=22%), and for those enrolled during a face-to-face follow-up home visit, rather than at the emergency department (ED) (follow-up=38%, ED=27%). Neither sex nor enrollment season were associated with retention. These findings underscore the importance of performing a comprehensive pilot study and considering a home residency period for participant enrollment eligibility, along with alternative study methods that take into account the challenges of retaining participants.