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Product adherence is critical to obtaining objective estimates of efficacy of pre-exposure prophylactic interventions against HIV-1 infection. With imperfect adherence, intention-to-treat analyses assess the collective effects of complete, sub-optimal and non-adherence, providing a biased and attenuated estimate of the average causal effect of an intervention. Using data from the MTN-020/ASPIRE phase III trial evaluating HIV-1 efficacy of the dapivirine vaginal ring, we conducted per-protocol, and adherence-adjusted causal inference analyses using principal stratification and marginal structural models. We constructed two adherence cut offs of ≥ 0.9 mg (low cutoff) and > 4.0 mg (high cutoff) that represent drug released from the ring over a 28-day period. The HIV-1 efficacy estimate (95% CI) was 30.8% (3.6%, 50.3%) (P = 0.03) from the per-protocol analysis, and 53.6% (16.5%, 74.3%) (P = 0.01) among the highest predicted adherers from principal stratification analyses using the low cutoff. Marginal structural models produced efficacy estimates (95% CIs) ranging from 48.8 (21.8, 66.4) (P = 0.0019) to 56.5% (32.8%, 71.9%) (P = 0.0002). Application of adherence-adjusted causal inference methods are useful in interpreting HIV-1 efficacy in secondary analyses of PrEP clinical trials., (© 2024. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

MTN-025/HOPE was an open-label trial of the dapivirine vaginal ring conducted in four African countries between 2016 and 2018. Women were first offered one ring monthly (at baseline, months 1 and 2), thereafter, transitioned to a more applicable real-world dispensation schedule, - 3 rings quarterly (at months 3, 6 and 9). Logistic regression analysis was used to assess correlates of ring acceptance at baseline and through follow-up. A total of 1456 women (median age 31 years) enrolled, 1342 (92.2%) accepted the ring at baseline and 1163 (79.9%) accepted the ring(s) at all visits. Changing ring dispensation from a monthly to a quarterly schedule had no negative effect on acceptance. Having a primary partner and him knowing about the ring being offered in HOPE, use of long-acting contraception (implants, injections, IUDs) or sterilization were associated with ring acceptance, along with prior strong intention to use the ring in the future. Efforts should consider these factors when rolling out the ring for HIV prevention., (© 2022. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Understanding characteristics associated with adherence to pre-exposure prophylaxis (PrEP) methods for HIV-1 prevention may assist with optimizing implementation efforts. The dapivirine vaginal ring is a novel topical PrEP delivery method. Using data from a randomized, double-blind, placebo-controlled, phase III trial of the dapivirine vaginal ring conducted in four African countries, generalized estimating equation models were used to evaluate correlates of ring adherence. Two levels of quarterly dapivirine blood plasma, and dapivirine released from returned rings defined measures of adherence for recent and cumulative use, respectively. Time on study, calendar time, primary partner knowledge that the participant was taking part in the study, and use of long-acting contraceptive methods were associated with ring adherence whereas younger age, ring worries, condom use, episodes of menstrual bleeding and vaginal washing were associated with non-adherence. These findings may be useful for recruitment into future clinical studies and dapivirine ring implementation efforts., (© 2021. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Gender roles and imbalances in sexual power contribute to the heightened HIV-1 risk faced by women in Sub-Saharan Africa. This has led prevention research to focus on the development of female controlled methods. Despite the design of products such as vaginal rings to be used autonomously by women, male partners and women's perceptions of relationships influence HIV prevention choices. To understand the influences that male partners and dyadic dynamics had on the use of the Dapivirine Vaginal Ring in the ASPIRE trial, this analysis of qualitative data explored the types of intimate partner relationships that women engaged in. This paper describes how partners facilitated or challenged women's ring use and how women dealt with these challenges within six different types of relationships characterized by power dynamics and commitment levels. We offer insights into how future use of female-initiated HIV prevention products can be promoted through recognition of different relationship types.