Objective: Efavirenz (EFV) along with two nucleoside reverse transcriptase inhibitors (NRTIs) is a recommended initial antiretroviral regimen. Understanding characteristics related to EFV success is clinically useful.
Design: Data from 2220 antiretroviral-naive participants randomized to EFV and two to three NRTIs in four ACTG trials as well as a long-term cohort were analysed.
Methods: Logistic regression, using inverse probability of censoring weighting to address selective-follow-up bias, was used to identify factors associated with EFV success (no treatment interruptions of >30 days, HIV RNA < 200 copies/ml) 1 year post initiation and at years 2–5 if successful at year 1.
Results: Pretreatment characteristics were median age 38 years, 82% male, 40% white, 10% history of IDU (HxIDU), median CD4+ T-lymphocyte 227 cells/μl and 33% HIV RNA more than 100 000 copies/ml. In a multivariable model, factors associated with year 1 EFV success were race [white odds ratio (OR) 1.5; P < 0.001; Hispanic OR 1.5; P = 0.003 vs. black], no pretreatment sign/symptom grade 3 or higher (OR 1.7; P = 0.008) and no HxIDU (OR 1.7; P = 0.001). Predictors of EFV success at years 2–5 were no HxIDU (years 2–5; ORs 1.9–2.2); self-reported complete (4 days prior to study visit) adherence during year 1 (years 2–4; ORs 1.6–1.9); fewer missed visits during year 1 (years 2, 4, 5; ORs 0.92–0.98/1% increase); HIV RNA less than 50 copies/ml at year 1 (years 2, 3; ORs 1.9–2.2); and older age (>50 vs. ≤30 years) (years 2–4: ORs 2.3–3.7).
Conclusion: Characteristics predictive of EFV success in the short-term and longer term differed except for HxIDU. Behaviours occurring during year 1 were associated with EFV success over 5 years.