Virological outcome at week 48 of three recommended first-line regimens using ultrasensitive viral load and plasma drug assay

Objectives: To describe the virological and pharmacological outcomes of three different recommended once-daily first-line regimens in a cross-sectional analysis within an observational cohort using ultra-sensitive HIV quantification. Patients and methods: We enrolled all HIV-1-infected patients who initiated tenofovir/emtricitabine with efavirenz, darunavir/ritonavir or atazanavir/ritonavir as a first-line regimen between 1 November 2010 and 30 June 2012. An ultrasensitive viral load (VL) assay was performed and plasma drug concentrations at 24 h (C-24) were determined at Week (W) 4, W12, W24, W36 and W48. Results: Sixty patients initiated efavirenz, 81 darunavir/ritonavir and 27 atazanavir/ritonavir. A higher proportion of patients with a VL. 100000 copies/mL received darunavir/ritonavir (P = 0.022). At W48, 89%, 85% and 88% of the patients had a VL,50 copies/mL, 69%, 73% and 79% had a VL <20 copies/mL and 45%, 48% and 54% had a VL <1 copy/mL using the ultrasensitive assay in the efavirenz, darunavir/ritonavir and atazanavir/ritonavir groups, respectively. Patients with a detectable VL signal at W48 had a higher baseline VL than those with no detectable VL signal (P=0.0001). A total of 92%, 93% and 91% of the efavirenz, darunavir and atazanavir C-24 values were above the respective effective cut-offs. Conclusions: In this observational cohort, the choice of the regimen was related to the physicians' preferences and the patients' characteristics. The proportion of patients reaching VL <1 copy/mL at W48 was similar in the three regimens and was not associated with drug concentrations.