Non-adherence, discontinuation, and seroconversion among people on daily HIV pre-exposure prophylaxis (PrEP) in Brazil: a nationwide cohort study

The goal of this study was to evaluate characteristics associated with Pre-exposure Prophylaxis for HIV infection (PrEP) non-adherence or discontinuation in Brazil and assess the association between these outcomes and HIV seroconversion. We used linked national dispensing and pathology data to identify people aged 14+ years initiating PrEP in 2018. We estimated non-adherence using the proportion of days covered (PDC), defining non-adherence as PDC < 60%. We defined discontinuation as a gap in therapy of at least 120 days. We used logistic regression models to assess characteristics associated with non-adherence or discontinuation within 365 days and to assess HIV seroconversion and its association with non-adherence or discontinuation. In 2018, 5100 people initiated PrEP; 34.4% (95%CI 33.1%; 35.7%) were non-adherent and 34.3% (95%CI 33.0%; 35.6%) discontinued. People aged 34 years or less, women, people with lower education levels, or living in the Northern region of Brazil were more likely to be non-adherent or discontinue therapy. Thirty people (0.6% 95%CI 0.4%; 0.8%) seroconverted. HIV seroconversion was associated with PrEP non-adherence or discontinuation (OR = 6.2 for both). Non-adherence and discontinuation were common in people initiating PrEP and strongly associated with HIV seroconversion. Our work identifies populations at higher risk of non-adherence or discontinuation which could be targeted in interventions to reduce new HIV cases in Brazil.