A prospective study of adherence and viral load in a large multi-center cohort of HIV-infected women

Objectives: To examine the relationship between antiretroviral adherence and viral load, and to determine the predictors of adherence over time in HIV-infected women. Design: Prospective observational study. Methods: One-hundred sixty-one HIV-infected women who were taking antiretroviral therapy for a median of 3.0 years were recruited from the HIV Epidemiology Research Study, a multicenter cohort study of HIV infection in women. Antiretroviral adherence (percent of doses taken as prescribed) was measured over a 6-month period using MEMS caps. At baseline and follow-up, CD4 lymphocyte count and viral load were measured, and a standardized interview was administered to elicit medication history and drug use behaviors. To examine changes in adherence over time, the mean adherence to all antiretroviral agents was calculated for each monitored month. Results: Adherence varied significantly over time (P < 0.001), ranging from a mean of 64% in month 1 to 45% in month 6. Nearly one-fourth of the participants had a 10% or greater decrease in adherence between consecutive months. Virologic failure occurred in 17% of women with adherence of ≥ 88%, 28% of those with 45-87% adherence, 43% of those with 13-44% adherence, and 71% of those with ≤ 12% adherence. In multivariate analysis, factors predicting lower adherence included active drug use, alcohol use, more frequent antiretroviral dosing, shorter duration of antiretroviral use, younger age, and lower initial CD4 lymphocyte count. Conclusions: Antiretroviral adherence is not stable over time. Interventions aimed at monitoring and improving long-term adherence in women are urgently needed.