The Relation Between Efavirenz. vs. Nevirapine and Virologic Failure in Johannesburg, South Africa

Abstract

Background: Previous research has raised concerns that patients given nevirapine (NVP)-based regimens experience more virologic failure than patients initiated on efavirenz (EFV)-based regimens. We investigated this hypothesis in a cohort of HIV-infected patients at a large HIV treatment clinic in South Africa. Methods: All antiretroviral therapy (ART)-naïve non-pregnant patients, ≥18 years old, without tuberculosis, who initiated treatment with either NVP or EFV between April 2004 and August 2011 at the Themba Lethu Clinic in Johannesburg, South Africa were included. We followed patients from ART initiation until an outcome (death, loss to follow-up (LTF), suppression, or failure), transfer, or 12 months of follow-up. Log-binomial regression was used to estimate risk ratios (RR) with 95% confidence intervals (CI) for predictors of failure, suppression, and LTF while a Cox proportional hazards model was used to estimate the risk of death. Results: Of 13015 included patients, 62.1% were female and the median (IQR) baseline CD4 count was 100 cells/mm3 (37-171). 93.2% initiated an EFV-based regimen. After adjusting for baseline characteristics, no difference in death (HR: 0.95; 95%CI: 0.70-1.29), LTF (RR: 0.96; 95%CI: 0.77-1.21), nor suppression (RR: 0.98; 95%CI: 0.96-1.01) at 1 year was found between regimens. Among patients  with at least 1 viral load within 1 year of ART initiation, 2.2% (n=217) experienced failure within 12 months of treatment initiation.  Patients initiating NVP-based regimens were more likely to experience failure than patients initiating an EFV-based regimen (4.4% vs. 2.0%). In an adjusted model, patients prescribed NVP were twice as likely to fail as patients prescribed EFV (RR: 2.16; 95%CI: 1.48-3.16). Conclusion: In this cohort, patients initiating NVP-based regimens experienced more failure than patients initiating EFV-based regimens. Future guidelines should consider the implications of different efficacy profiles when making recommendations.

Conference: SA AIDS 2013, Durban, SA