Background
New HIV cases continue to rise in Latin America, especially among young men who have sex with men (MSM) and transgender women (TGW). Understanding long-term oral PrEP use is crucial for improving adherence and retention to services. This study explored PrEP use patterns over time in Brazil, identifying distinct trajectories and associated factors.
Methods
ImPrEP was a prospective, single-arm, multicenter oral PrEP study conducted in Brazil, Mexico, and Peru . Eligible MSM/TGW (aged ≥18, HIV-negative, risk behaviors in past 6 months). For this analysis, we included Brazilian participants followed from Feb 2018 to Jul 2024. Group-based trajectory models identified adherence patterns using MPR ≥ 0.6 (possessing at least 4 PrEP pills/week) as reference for adequate adherence. A multinomial model assessed factors associated to belonging to each group. Discontinuation was defined as not receiving PrEP for at least six months and not returning until the end of follow-up.
Results
Of 3,928 enrolled, 3,780 returned for at least one follow-up visit and were included in this analysis. Median follow-up duration was 2.97 years (IQR:1.30–5.13years); 11,797.56 person-years. We identified 3 distinct trajectories: G1 (60%) with consistent probability of having adequate adherence during follow-up, G2 (36%) with gradual decline in adequate adherence, while G3 (4%) with rapid decline (Figure). Higher odds of being in G2 and G3 compared to G1 were younger age (G2: aOR=1.50, 95%CI:1.26–1.79; G3: aOR=1.83, 95%CI:1.18–2.85), transactional sex (G2: aOR=1.44, 95%CI:1.10–1.88; G3: aOR=1.82, 95%CI:0.96–3.44), and stimulant use (G2: aOR=1.24, 95%CI:1.04–1.48). Overall, 66% discontinued PrEP during follow-up, and HIV incidence was higher among them compared to those on PrEP (1.67 [95%CI:1.34-2.06] vs. 0.26 [95% CI:0.18-0.36]). HIV incidence rate was 4.22 times (95%CI;1.66-14.09; p=0.002) higher in G3 than in G1 (G1: 0.18 [95%CI:0.11-0.33]; G2: 0.29 [95%CI:0.17-0.48]; G3: 0.97 [95%CI: 0.40-2.32]).
Conclusions
We identified 3 distinct oral PrEP adherence trajectories in Brazil, with those with rapid adherence decline being of younger age, engaging in transactional sex, and using stimulant drugs. Higher HIV incidence among those who discontinued PrEP underlines the importance of retention in PrEP services. Long-acting PrEP technologies may help address the unique challenges faced by these subgroups, enhancing PrEP retention and overall effectiveness.