CD4 cell count and viral load-specific rates of AIDS, non-AIDS and deaths according to current antiretroviral use.

BACKGROUND: CD4 cell count and viral loads are used in clinical trials as surrogate endpoints for assessing efficacy of newly available antiretrovirals. If antiretrovirals act through other pathways or increase the risk of disease this would not be identified prior to licensing. The aim of this study was to investigate the CD4 cell count and viral load-specific rates of fatal and nonfatal AIDS and non-AIDS events according to current antiretrovirals. METHODS: Poisson regression was used to compare overall events (fatal or nonfatal AIDS, non-AIDS or death), AIDS events (fatal and nonfatal) or non-AIDS events (fatal or nonfatal) for specific nucleoside pairs and third drugs used with more than 1000 person-years of follow-up (PYFU) after 1 January 2001. RESULTS: Nine thousand, eight hundred and one patients contributed 42372.5 PYFU, during which 1203 (437 AIDS and 766 non-AIDS) events occurred. After adjustment, there was weak evidence of a difference in the overall events rates between nucleoside pairs (global P-value = 0.084), and third drugs (global P-value = 0.031). As compared to zidovudine/lamivudine, patients taking abacavir/lamivudine [adjusted incidence rate ratio (aIRR) 1.22; 95% CI 0.99-1.49] and abacavir and one other nucleoside [aIRR 1.51; 95% CI 1.14-2.02] had an increased incidence of overall events. Comparing the third drugs, those taking unboosted atazanavir had an increased incidence of overall events compared with those taking efavirenz (aIRR 1.46; 95% CI 1.09-1.95). CONCLUSION: There was little evidence of substantial differences between antiretrovirals in the incidence of clinical disease for a given CD4 cell count or viral load, suggesting there are unlikely to be major unidentified adverse effects of specific antiretrovirals.

A randomized trial to study first-line combination therapy with or without a protease inhibitor in HIV-1-infected patients.

OBJECTIVE: To compare one protease inhibitor (PI)-based and two PI-sparing antiretroviral therapy regimens. METHODS: International, open label, randomized study of antiretroviral drug-naive patients, with CD4 lymphocyte counts >/= 200 x 106 cells/l and plasma HIV-1 RNA levels > 500 copies/ml. Treatment assignment to stavudine and didanosine plus indinavir or nevirapine or lamivudine. Primary study endpoint was the percentage of patients with plasma HIV-1 RNA levels < 500 copies/ml after 48 weeks in the intention-to-treat analysis (ITT). RESULTS: In total, 298 patients were enrolled. After 48 weeks, the percentage of patients in the indinavir, nevirapine and lamivudine arms with HIV-1 RNA < 500 copies/ml was 57.0%, 58.4% and 58.7%, respectively, in an ITT analysis. After 96 weeks of follow-up, these percentages were 50.0%, 59.6% and 45.0%, respectively. The percentage of patients with HIV-1 RNA < 50 copies/ml was significantly less for those allocated to lamivudine in an on-treatment analysis after 48 and 96 weeks of follow-up. Patients in the nevirapine arm experienced a smaller increase in the absolute number of CD4 T lymphocytes. There were no significant differences in the incidence of serious adverse events. CONCLUSIONS: A comparable virological response can be achieved with first-line PI-base and PI-sparing regimens. The triple nucleoside regimen utilized may be less likely to result in viral suppression to < 50 copies/ml, while the nevirapine-based regimen is associated with a lower increase in CD4 T lymphocytes.