Six-year follow-up of HIV-1-infected adults in a clinical trial of antiretroviral therapy with indinavir, zidovudine, and lamivudine.

Objective: To assess virological and immunological responses and toxicity in subjects receiving combination antiretroviral therapy.

Design: Six-year follow-up of a single arm of a randomized study of combination antiretroviral therapy.

Methods: HIV-infected, zidovudine-experienced patients originally randomized to receive indinavir, zidovudine, and lamivudine had HIV RNA levels and CD4 cell counts assessed over 6 years. Information was collected by questionnaire from subjects who discontinued the study regimen before 6 years. Both on-study and post-study responses were assessed.

Results: Of 33 subjects, 16 (48%) discontinued before 6 years of follow-up. After 6 years, 16 (53%) and 14 (47%) of 30 contributing subjects had HIV RNA levels < 500 and < 50 copies/ml, respectively, and the median increase in CD4 cell count from baseline for 28 contributing subjects was 268 x 10(6) cells/l. Treatment-limiting nephrolithiasis occurred in four subjects. Of the 16 subjects who discontinued the study, 12 had post-study questionnaire data available and seven had HIV RNA < 500 copies/ml on a post-study regimen. In an exploratory analysis combining both on-study and post-study data at approximately 6 years, 26 (79%) and 19 (58%) of 33 had HIV RNA levels < 500 and < 50 copies/ml, respectively, and the median increase in CD4 cell count from baseline was 344 x 106 cells/l.

Conclusions: Antiretroviral therapy with indinavir, zidovudine, and lamivudine suppressed HIV viremia and produced continued CD4 cell increases in a majority of subjects for 6 years. Most subjects who discontinued study medications had HIV RNA levels suppressed on post-study therapy. Though based on a small group, this study demonstrates the durable effects of antiretroviral therapy.