Adherence, virological and immunological outcomes for HIV-infected veterans starting combination antiretroviral therapies

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Abstract
Objectives: We aimed to determine adherence, virological, and immunological outcomes one year after starting a first combination antiretroviral therapy (ART) regimen. Design: Observational; synthesis of administrative, laboratory, and pharmacy data. Antiretroviral regimens were divided into efavirenz, nevirapine, boosted protease inhibitor (PI), and single PI categories. Propensity scores were used to control for confounding by treatment assignment. Adherence was estimated from pharmacy refill records. Setting: Veterans Affairs Healthcare System, all sites. Participants: HIV-infected individuals starting combination ART with a low likelihood of previous antiretroviral exposure. Interventions: None. Outcomes: The proportion of antiretroviral prescriptions filled as prescribed, a change in log HIV-RNA, the proportion with log HIV-RNA viral suppression, a change in CD4 cell count. Results: A total of 6394 individuals unlikely to have previous antiretroviral exposure started combination ART between 1996 and 2004, and were eligible for analysis. Adherence overall was low (63% of prescriptions filled as prescribed), and adherence with efavirenz (67%) and nevirapine (65%) regimens was significantly greater than adherence with boosted PI (59%) or single PI (61%) regimens (P < 0.001). Efavirenz regimens were more likely to suppress HIV-RNA at one year (74%) compared with nevirapine (62%), boosted PI (63%), or single PI (53%) regimens (all P < 0.001), and this superiority was maintained when analyses were adjusted for baseline clinical characteristics and propensity for treatment assignment. Efavirenz also yielded more favorable immunological outcomes. Conclusion: HIV-infected individuals initiating their first combination ART using an efavirenz-based regimen had improved virological and immunological outcomes and greater adherence levels.