Understanding how women use PrEP is important for developing successful implementation programs. We hypothesized there are distinct patterns of adherence, related to HIV risk and other factors. We identified patterns of PrEP adherence and HIV risk behavior over the first 6 months of PrEP use, using data from 233 HIV-uninfected women in high-risk serodiscordant couples in a demonstration project in Kenya & Uganda. We modeled PrEP adherence, assessed by daily electronic monitoring, and HIV risk behavior using group-based trajectory models. We tested baseline covariates and risk behavior group as predictors of adherence patterns. There were four distinct adherence patterns: high steady adherence (55% of population), moderate steady (29%), late declining (8%), and early declining (9%). No baseline characteristics significantly differed between adherence patterns. Adherence patterns differed in average weekly doses (6.7 vs 5.4 vs 4.1 vs 1.5, respectively). Two risk behavior groups were identified: steady HIV risk (78% of population) and declining (22%). Compared to women with declining HIV risk behavior, women with steady risk behavior were more likely to have high steady adherence (61% vs 35%) and less likely to have early (6% vs 17%) or late (4% vs 19%) declining adherence. Women's use of PrEP was associated with concurrent HIV risk behavior; higher risk was associated with higher, sustained adherence.
Keywords: Adherence; Africa; HIV; Patterns; Pre-exposure prophylaxis; Women.