Understanding differences in enrollment outcomes among high-risk populations recruited to a phase IIb HIV vaccine trial.

BACKGROUND

The Step Study, a Phase IIb HIV vaccine proof of concept study, enrolled approximately 3000 persons in clade B regions. The Atlanta site sought to enroll a diverse population. This prospective cohort study examined key factors associated with participant enrollment.

METHODS

We obtained participant information (eg, sociodemographic, medical) and followed outcomes from 2005 to 2007. Of the 810 potential "Step Study" participants, 340 cases were analyzed.

RESULTS

The recruitment strategy generated strong interest among minorities with 37% eligible after prescreening, yet 25% of the minorities enrolled. However, the percentage of whites increased from 62% eligible (prescreened sample) to 75% enrolled. The regression model was significant with educational level being an enrollment predictor (P = 0.0023). Those with at least a bachelor's degree were more likely to enroll compared with those with a K-12 education or some college (odds ratio = 2.424, 95% confidence interval = 1.372 to 4.281, P < 0.01). White race was also a significant factor (odds ratio = 2.330; 95% confidence interval = 1.241 to 4.375, P < 0.01). No difference in enrollment was observed among recruitment approaches, Pearson chi (2) (n = 336) = 5.286, P = 0.07.

CONCLUSIONS

The results from this study indicate that women, minorities, and those with lower educational attainment were less likely to enroll in an HIV vaccine efficacy study at our site. The findings highlight an important consideration on the role of health literacy to sustain participation of eligible minorities in HIV vaccine trials.