Abstract:
Despite sparse efficacy data, tenofovir–emtricitabine or tenofovir–lamivudine plus nevirapine is used in many
resource-constrained settings.
Methods. This retrospective cohort study included patients initiating nevirapine-based antiretroviral therapy (ART) with either
tenofovir–emtricitabine or lamivudine (tenofovir group) or zidovudine–lamivudine (zidovudine group). Clinical, virologic, and immunologic
evaluations were performed at baseline and every 6 months. Virologic failure was defined as 2 consecutive human immunodeficiency
virus (HIV)-RNAvalues >1000 copies/mL. Patients were included from ART initiation until time of failure, regimen
switch, discontinuation, or last HIV-RNA measurement. Cox proportional hazards regression was used to model factors influencing
time to failure. Bias due to dependent censoring was investigated via inverse probability weighted pooled logistic regression.
Results. A total of 5547 patients were evaluated; 1484 (26.8%) were in the tenofovir group and 4063 (73.2%) were in the zidovudine
group. In the adjusted model, tenofovir regimen (hazard ratio [HR], 1.47; 95% confidence interval [CI], 1.21–1.79) and higher
baseline log10 HIV-RNA (HR, 1.15; 95% CI, 1.03–1.28) were associated with virologic failure. Higher baseline log10 CD4+ cell count
(HR, 0.50; 95% CI, .40–.63) and increasing age (HR, 0.98; 95% CI, .97–.99) decreased the risk of virologic failure. Inverse probability
weighting results were consistent with the primary analysis.
Conclusions. Compared with zidovudine–lamivudine, the use of tenofovir–lamivudineoremtricitabine in combination with nevirapine
was a strong predictor of virologic failure in our cohort, which was not explained by other risk factors or criteria for regimen selection.
