Enrollment of Minorities into Health Research: A Meta-Analysis of Recruitment Methods

Purpose: The study's aim is to identify the relative effectiveness of methods utilized by U.S. research studies to recruit minority adults. The studies were conducted between 1994, when the NIH policy guidelines on inclusion of minorities in clinical trials were issued, and 2007.

Method: A meta-analysis of studies that enrolled race/ethnic minorities was conducted. We searched PUBMED, CINAHL, Psycinfo for original studies using terms that included recruitment, research, clinical trials, minorities, eight race/ethnic groups, 11 recruitment methods. We manually searched journals (n=6) that yielded at least five articles. The number individuals contacted and enrolled by recruitment method, race/ethnicity and sex, study duration (months), type of study (survey vs. clinical trials) were collected. The Comprehensive Meta-analysis program (random effects model) was used.

Results: Seventy-one studies with 221,762 enrollees out of 782,202 contacts were analyzed. Of these, 58% , 17.1%, 7.1%, 5.7% involved only African-Americans, Hispanics, Asians and Native Americans, respectively; 11.4% enrolled multiple racial/ethnic groups. Women made up 57.1% of total enrollees. Forty-seven of the studies required the subject to only complete a questionnaire. The remaining 24 studies had an average duration of 25 months. An overall enrollment rate was not significant. Of the seven methods, face-to-face (78% enrollment rate), telephone (64%), media (29%) and direct mail (28%) were significant. Unlike race/ethnicity and sex, study duration and study type were significant (negative) moderators of enrollment rates.

Conclusions: These findings suggest that personal contact methods are most effective in recruiting minorities into health research and that participation burden negatively affects enrollment rates.