Predictors of Virologic and Clinical Outcomes in HIV-1–Infected Patients Receiving Concurrent Treatment with Indinavir, Zidovudine,

Background: A substantial proportion of patients with HIV in-fection will not respond to antiretroviral therapy. Early predictors of response to treatment are needed to identify patients who are at risk for treatment failure. Objective: To determine predictors of virologic and clinical re-sponse to indinavir, zidovudine, and lamivudine therapy. Design: Observational analysis of one treatment group in a phase III trial. Setting: 40 AIDS Clinical Trials units. Patients: 489 patients receiving indinavir, zidovudine, and lami-vudine who had 1) a CD4 count of 0.200 3 109 cells/L or less after 8 or more weeks of study therapy and 2) plasma HIV-1 RNA measurements obtained at baseline and week 8. Measurements: HIV-1 RNA level and CD4 cell count at weeks 0, 4, 8, 24, and 40. Clinical progression was defined as a new AIDS-defining illness or death. Results: Patients ’ levels of HIV-1 RNA at the 8th study week of therapy predicted whether patients would achieve virologic sup-pression to below 500 (or 50) copies/mL at study week 24. An HIV-1 RNA level less than 500 copies/mL at week 24 was achieved in 71 % of patients whose level at week 8 had been less than 500 copies/mL, 53 % of those with a level of 500 copies/mL or more and at least 2–log10 copies/mL reduction since baseline, 29 % of those with a level of 500 copies/mL or more with a 1 – to 1.99–log10 copies/mL reduction, and 9 % of those with a level of 500 copies/mL or greater and less than 1–log10 copies/mL reduc-tion since baseline (P < 0.001). HIV-1 RNA level at week 8 also predicted clinical progression. HIV-1 disease progressed in 2.2% of the patients with a week-8 HIV-1 RNA level less than 500 copies/mL, 2.3 % of patients with 500 copies/mL or greater and at least 2–log10 copies/mL reduction since baseline, 4.9 % of patients with 500 copies/mL or greater and 1 – to 1.99–log10 copies/mL reduction since baseline, and 10.6 % of patients with 500 cop-ies/mL or greater and less than 1–log10 copies/mL decrease sinc