Response to first protease inhibitor- and efavirenz-containing antiretroviral combination therapy - The Swiss HIV Cohort Study

Objective: To compare the response to protease inhibitor (PI) and efavirenz -containing combination therapy among treatment-naive HIV-infected persons. Design: Prospective observational cohort study. Methods: Response to treatment was analysed according to the intent-to-trea t principle among anti retroviral-naive patients who started either efavire nz (n = 89) or PI (n = 183) plus two nucleoside reverse transcriptase inhib itors between February 1999 and March 2000 using Kaplan-Meier and multivari able Cox proportional hazard regression methods. Primary endpoint was time to undetectable plasma viral load. Secondary endpoints included the number of CD4 cells gained, virological rebound, treatment change, and clinical pr ogression. Results: Patients on PI regimens had lower median CD4 counts (165 versus 21 6 x 5 10(6)/I; P = 0.15) and were more likely to have AIDS at initiation of treatment (25% versus 15% P = 0.048) than patients starting efavirenz regi mens. The probability of reaching plasma HIV-1 RNA < 400 copies/ml was high er with efavirenz- than with PI-containing regimens [adjusted hazard ratio, 1.75; 95% confidence interval (CI), 1.34-2.29]. Median times to undetectab le viral load were 58 days (95% CI, 44-70 days) for efavirenz-treated and 8 8 days (95% CI, 79-98 days) for PI-treated patients. The median number of C D4 cells gained in the first 6 months (90 x 10(6) cells/I with efavirenz, 1 07 x 10(6) cells/I with PI; P = 0.63), time to and reasons for treatment ch ange, time to viral rebound, drug intolerance and clinical progression rate s were similar in the two treatment groups. Conclusions: Treatment with efavirenz-, compared with PI-based regimens, ap peared to result in a superior virological response but no difference in im munological or clinical efficacy. The relevance of these observations remai ns to be determined in studies with longer follow-up. (C) 2001 Lippincott W illiams & Wilkins.