High adherence to HIV PrEP among clinic attendees over 12 months in the PRELUDE open-label demonstration project

Abstract

Introduction: The efficacy of HIV pre-exposure prophylaxis (PrEP) depends upon adherence. Facilitated recall is a practical measure to monitor patients’ adherence to PrEP in clinical practice. Data from the PRELUDE Demonstration Project were used to investigate patterns and predictors of adherence to daily PrEP over 12 months. Methods: PRELUDE was an open-label study of high-HIV risk individuals taking PrEP in New South Wales, Australia. PrEP adherence was assessed quarterly for one year. Participants were asked by clinicians about the number of pills taken in the previous week (facilitated recall). Adjusted odds ratios (aOR) and 95% confidence intervals (95%CI) for factors associated with daily adherence were calculated using generalised estimating equations for longitudinal data. Results: Of the 321 gay/bisexual men (GBM) enrolled in the study, 263 (82%) remained on study at month 12. Of these, 243 (92%) and 230 (87%) reported daily adherence (7 pills/week) at month and 12, respectively. Adherence declined by 10% during the study (aOR 0.90, 95%CI 0.84-0.95, p<0.001). In multivariate analysis, participants were more likely to report taking 7 pills in the previous week if they had engaged in group sex in the previous three months (aOR 1.33, 95%CI 1.15-1.53) or attended a private clinic (aOR 1.50, 95%CI 1.07-2.11). Conclusions: Among participants who completed one year of follow-up on PRELUDE, daily PrEP use was more likely among those at ongoing risk of HIV due to their behaviours. The moderate loss to follow-up in the cohort is not surprising, as individuals are not expected to remain on PrEP forever, but rather, during periods of risk. Combined, these results suggest that GBM in this study who are highly engaged with healthcare systems can identify times when they are at increased risk of contracting HIV and act accordingly, taking PrEP consistently as recommended during this time