Correlates of adherence to the dapivirine vaginal ring for HIV-1 prevention


BACKGROUND: Understanding characteristics associated with adherence to pre-exposure prophylaxis (PrEP) methods for HIV-1 prevention may assist with optimizing implementation efforts for these products. The dapivirine vaginal ring is a novel topical PrEP delivery method. The aim of this study was to discover baseline and time-dependent correlates of adherence to ring use.
METHODS: Using data from a randomized, double-blind, placebo-controlled, phase III trial of the dapivirine vaginal ring in four African countries, we constructed generalized estimating equation models with exchangeable working correlation structure to evaluate correlates of adherence. Two levels of quarterly dapivirine blood plasma (>95 pg/mL and >200 pg/mL), and dapivirine released from returned rings ('¥0.9 mg and >4.0 mg) defined measures of adherence for recent and cumulative use, respectively. Baseline and time-varying covariates evaluated in multivariable models included demographics, sexually transmitted infections, sexual risk, partner characteristics, family planning methods, menstrual bleeding, vaginal practices and worries associated with ring use.
RESULTS: As in Table 1, longer time on study, later calendar time, primary partner knowledge that the participant was taking part in the study, and use of long-acting contraceptive methods were positively associated with measures of ring adherence. Younger age, ring worries, condom use, episodes of menstrual bleeding and vaginal washing were negatively associated with measures of ring adherence.

table 1 - husnik mj et al. mtn-020 (aspire) correlates of adherence pg1.jpg

CONCLUSIONS: These findings will be useful for recruitment into future clinical studies, real-time adherence monitoring and dapivirine ring implementation efforts. Evaluating multiple biomarkers of adherence provides a more thorough understanding of correlates of ring adherence and could strengthen the design of future adherence marker studies.