Retention of clinical trial participants in a study of nongonococcal urethritis (NGU), a sexually transmitted infection in men.

Nongonococcal urethritis (NGU), an inflammation of the urethra not caused by gonorrhea, is the most common urethritis syndrome seen in men in the United States. It is a sexually transmitted infection commonly caused by Chlamydia trachomatis, a pathogen which occurs more frequently in African-American men compared to white men. The purpose of this study was to investigate factors related to retention of study participants in a randomized, double-blinded clinical trial that evaluated four treatment regimens for the treatment of NGU. After the one-week treatment period, follow-up visits were scheduled during days 15-19 and days 35-45. Participants were phoned prior to scheduled appointments to encourage attendance, and contacted after missed appointments to reschedule their clinic visits. Of the 305 male study participants, 298 (98%) were African-American, 164 (54%) were 25 years of age or younger, and 80 (31%) had a post-secondary school education. The overall retention rate was 75%. Factors associated with study completion were educational level attained and clinical center. Participants with higher levels of education were more likely to complete the study. Clinical centers with the highest retention rates also provided the highest monetary incentives for participation. The retention rate for this study suggests that strategies are needed for improving the proportion of study participants that complete a clinical trial among young men with a sexually transmitted disease. These strategies may include increasing contacts with study participants to remind them of scheduled study visits using text messaging or social media and the use of financial incentives.