Addiction treatment trials: How gender, race/ethnicity, and age relate to ongoing participation and retention in clinical trials.

Historically, racial and ethnic minority populations have been underrepresented in clinical research, and the recruitment and retention of women and ethnic minorities in clinical trials has been a significant challenge for investigators. The National Drug Abuse Treatment Clinical Trials Network (CTN) conducts clinical trials in real-life settings and regularly monitors a number of variables critical to clinical trial implementation, including the retention and demographics of participants. This study examined gender, race/ethnicity, and age group differences with respect to retention characteristics in CTN trials. Reports for 24 completed trials that recruited over 11,000 participants were reviewed, and associations of gender, race/ethnicity, and age group characteristics were examined along with the rate of treatment exposure, the proportion of follow-up assessments obtained, and the availability of primary outcome measure(s). Analysis of the CTN data did not indicate statistical differences in retention across gender or race/ethnicity groups; however, retention rates increased for older participants.

Conclusion: The participation and ongoing retention rates of 70-80% did not differ by race/ethnicity or gender. However, participation and retention rates increased significantly with age. These results highlight the need to investigate the reason(s) why younger adult rates of participation are lower.