Effect of antiretroviral therapy on viral load, CD4 cell count, and progression to acquired immunodeficiency syndrome in a community human immunodeficiency virus-infected cohort

Objective: To examine the effect of different antiretroviral treatment regi mens on viral load, CD4 lymphocyte counts, and rates of progression to clin ical acquired immunodeficiency syndrome events among treatment-naive human immunodeficiency virus (HIV)-infected patients enrolled in a large communit y cohort study. Methods: Based in 7 outpatient clinics, the Swiss HIV Cohort Study is a coh ort with national coverage, Virological, immunologic, and clinical results of 755 treatment-naive patients (median age, 36 years; 28.2% female) who in itiated antiretroviral therapy between July 1, 1995, and lune 30, 1997, wer e analyzed. Patients started undergoing monotherapy with 1 reverse transcri ptase inhibitor (RTI), combination therapy with at least 2 RTIs, or highly active antiretroviral therapy (HAART) with RTIs and protease inhibitors. Results: Antiretroviral treatment led to a mean reduction of viremia of 1.8 log(10) copies per milliliter with HAART, 1.2 log(10) copies per millilite r with RTI combination therapy, and 0.4 log(10) copies per milliliter with monotherapy. Virological failure, defined as less than 1 log,, reduction pe r milliliter in viremia, was present in 45 (20%) patients undergoing HAART, 180 (38%) undergoing RTI combination therapy, and 47 (82%) undergoing mono therapy. The proportion of patients reaching undetectable viremia was 12% ( n = 7) for monotherapy, 41% (n = 197) for RTI combination therapy, and 63% (n = 137) for HAART. Similar gains of CD4 cells were achieved with RTI comb ination therapy and HAART. Kaplan-Meier estimates of progression rates to a new acquired immunodeficiency syndrome event at 18 months were 13.6% (mono therapy), 4.7% (RTI combination therapy), and 3.9% (HAART). Conclusions: The rare of virological failure of antiretroviral treatments w as high in this population of treatment-naive patients, even among patients receiving combination regimens. Clinical progression rates were, however, low in patients treated with RTI combination therapy and HAART.