Duration of first-line antiretroviral therapy with enofovir and emtricitabine combined with atazanavir/ritonavir, efavirenz or lopinavir/ritonavir in the Italian ARCA cohort

OBJECTIVES: The explore the durability of three first-line tenofovir/emtricitabine-based regimens in combination with atazanavir/ritonavir, efavirenz or lopinavir/ritonavir in HIV-1 infected patients. PATIENTS AND METHODS: A retrospective, longitudinal, multicentre analysis of adult patients enorlled in the Antiretroviral Rsistance Cohort Analysis (ARCA), a national prospective observational cohort of HIV-1 infected patients followed up at more than 100 clinical and laboratory units in Italy. Patients eligible were those starting first-line antiretroviral therapy between 1 June 2004 and 15 Aprile 2011 and who were followed up for at least 6 moths. The primary endpoint wad durability, defined as the time from antiretroviral therapy initiation to first treatment modification. Time-dependent events were analysed by the Kaplan-Meier approach and the Cox roportonial hazard model. RESULTS: There are 26,000 HIV -infected patients in the ARCA database, of whom 1654 met study inclusion criteria. Six hundred and thirty-nine (38.6%) received efabirenz, 321 (19.4%) received atazanavir/ritonavir and 694 (41.9%) received lopinavir/ritonavir as a first-line regimen. Over a total observation period of 88 months, equivalent to more than 2805 person-years of follow-up, 628 patients underwent treatment modification. Lopinavir/ritonavir, given twice daily, was associated with a higher discontinuation rate than efavirenz- and atazanavir- based regimens (hazard ratio (HR) 1.83, 95% confidence interval (CI) 1.56-2. 15, P = 0.001). Comparing the once-daily regimens, the rate of discontinuation of efavirenz was higher than that of atazanavir/ritonavir (HR 1.39, 95% CI 1.06-1.83, P = 0.016). CONCLUSIONS: Significant differences in treatment duration were observed among the three studied regimes. Once-daily regimesn exhibited Greater durability than the twice-daily regimen. Among the specific regimens examined, tenofovir/emtricitabine plus atazanavir/ritonavir showed the greatest durability.