Impact of baseline virologic, immunologic, and demographic characteristics on virologic responses in the Gemini study.

Purpose: To determine the impact of baseline viral load (VL) and CD4+ cell count, race/ethnicity, and gender on response in a post hoc analysis of the Gemini study.

Methods: In this 48-week study, treatment-naïve, HIV-infected participants received as initial therapy twice-daily saquinavir/ritonavir (SQV/r) 1000/100 mg (n=167) or lopinavir/ritonavir (LPV/r) 400/100 mg (n=170), each with emtricitabine 200 mg/tenofovir 300 mg daily. The proportion of participants achieving HIV RNA<50 copies/mL (primary endpoint) and median change from baseline in CD4+ cell count were compared by baseline VL (>100,000 vs ≤ 100,000 copies/ mL) and CD4+ cell count (>100 vs ≤ 100 cells/µL). The impact of baseline and demographic variables on virologic response was assessed by logistic regression analysis.

Results: Responses were similar between arms (SQV/r vs LPV/r) with or without stratification. In a pooled analysis of SQV/r and LPV/r arms, CD4+ cell count >100 cells/µL (odds ratio [OR], 1.628;P = .0416), non-Thai/non-Black versus Black race (OR, 1.518;P = .0023), and non-Thai/non-Black versus Thai (OR, 0.467;P = .0046) were significant predictors of virologic response.

Conclusions: Treatment groups had similar efficacy. Baseline CD4+ cell count and race/ethnicity were independent predictors of virologic response, whereas baseline VL and gender were not.