Abstract
One of the key pillars of Ending the HIV Epidemic is ensuring adherence to oral HIV pre-exposure prophylaxis (PrEP). Men who have sex with men (MSM) who also have substance use disorders experience multiple challenges to maintaining PrEP adherence. We developed a digital pill system (DPS) linked to a personalized adherence intervention, PrEPSteps, to address barriers to PrEP adherence, and tested the feasibility and acceptability of this system, as well as its potential for an effect on PrEP adherence. We enrolled MSM with moderate to severe substance use disorder who were on oral PrEP in a two-arm pilot randomized controlled trial. Both arms received the DPS co-encapsulated with oral PrEP. Participants in the intervention arm also received "PrEPSteps" - a personalized cognitive-behavioral adherence intervention. Primary outcomes were feasibility and acceptability of DPS + PrEPSteps. To explore potential intervention effects, adherence changes from baseline to 3-month follow-up were compared across arms. At 6-month follow-up, adherence was assessed via self-report. Thirty-six participants were enrolled, 32, completed the run-in period, 28 were randomized, and 27 completed the 3-month intervention period. Of those, 26 completed six-month follow-up. Operation of the DPS and PrEPSteps was feasible, with consistent data recording throughout the 3-month intervention period. Qualitative interviews in the intervention arm at 3 months demonstrated PrEPSteps was acceptable. Intervention arm participants had 14% higher PrEP adherence (b = 13.67, 95%CI [.77-26.57], p = .039) at 3 month follow up. This effect persisted at six months, suggesting that PrEPSteps has the potential to improve PrEP adherence and help individuals sustain adherence benefits over time.Trial registration: www.ClinicalTrials.gov identifier: NCT03512418.