Higher efficacy of nevirapine than efavirenz to achieve HIV-1 plasma viral load below 1 copy/ml.

Objectives: To compare the level of HIV-1 residual viremia, defined by a viral load below 50 copies/ml in patients receiving a tenofovir/emtricitabine and nevirapine (NVP) or efavirenz (EFV)-containing regimen.

Design: One hundred and sixty-five HIV-1-infected patients were retrospectively included since they achieved virological suppression (viral load <50 copies/ml) for at least 6 months with a tenofovir/emtricitabine and non-nucleoside reverse transcriptase inhibitor-containing regimen (NVP, n = 75 and EFV, n = 90).

Methods: Residual plasma viremia was measured using an ultrasensitive assay with a limit of quantification of 1 copy/ml. A Fisher's exact test was used to compare the percentage of patients with HIV-1 RNA below 1 copy/ml between the two treatment groups. Logistic regression was used to search for factors associated with a viral load below 1 copy/ml among the different patient characteristics.

Results: Patients in the NVP group had more frequently a viral load below 1 copy/ml than patients in the EFV group (81.3 vs. 55.6%, P < 0.001). In multivariate analysis, only NVP vs EFV (P = 0.005) and duration of viral suppression under antiretroviral treatment (P = 0.005) were independently associated with viral load below 1 copy/ml.

Conclusions: It is well known that NVP has a good penetration in anatomic compartments that could explain a deep control of virus replication in some compartments and consequently decrease the residual level of viral load. The clinical relevance of having a viral load below 1 copy/ml has now to be studied for example on systemic inflammatory or immune activation markers.