Efficacy and safety of a switch to unboosted atazanavir in combination with nucleoside analogues in HIV-1-infected patients with virological suppression under antiretroviral therapy

Abstract

Limited data are available on the use of unboosted atazanavir in combination with nucleoside reverse transcriptase inhibitors (NRTIs) in treatment-experienced HIV-infected patients. We conducted a multicentre, retrospective study among patients with plasma HIV-1 RNA levels <50 copies/mL under antiretroviral therapy who switched to unboosted atazanavir + NRTIs between January 2002 and December 2008. Virological failure during follow-up was defined as a confirmed plasma HIV-1 RNA level >50 copies/mL. Baseline risk factors for virological failure were identified using Cox proportional hazards models. A total of 886 patients were analysed. At baseline, median age was 44 years, 71.5% were males and median CD4 cell count was 490 cells/mm(3). NRTIs used in combination with atazanavir were tenofovir, abacavir and emtricitabine/lamivudine in 36.9%, 44.1% and 94.4% of patients, respectively. Median follow-up was 21 months. The 3 year probability of virological failure was 20.1%. Only a history of virological failure under NRTIs [hazard ratio (HR) 1.63, P = 0.049] and under protease inhibitors (HR 2.04, P = 0.006) were significantly associated with the risk of virological failure. Among the 431 patients without a prior history of virological failure, the 3 year probability of virological failure was 11.3%, and only hepatitis C virus co-infection (HR 2.25, P = 0.026) and abacavir use (HR 0.43, P = 0.04) were associated with the risk of virological failure. Safety of the switch was satisfactory, with improvement of the lipid profile. In patients with virological suppression and no prior history of virological failure, a switch to unboosted atazanavir in combination with NRTIs is associated with a low probability of virological failure and a good safety profile.