Improved survival among HIV-infected individuals following initiation of antiretroviral therapy

Abstract

Context: Clinical trials have established the efficacy of antiretroviral therapy with double- and triple-drug regimens for individuals infected with the human immunodeficiency virus (HIV), but the effectiveness of these regimens in the population of patients not enrolled in clinical trials is unknown.

Objective: To characterize survival following the initiation of antiretroviral therapy among HIV-infected individuals in the province of British Columbia.

Design: Prospective, population-based cohort study of patients with antiretroviral therapy available free of charge (median follow-up, 21 months).

Setting: Province of British Columbia, Canada.

Patients: All HIV-positive men and women 18 years of age or older in the province who were first prescribed any antiretroviral therapy between October 1992 and June 1996 and whose CD4+ cell counts were less than 0.350 x 10(9)/L.

Main outcome measures: Rates of progression from initiation of antiretroviral therapy to death or a primary acquired immunodeficiency syndrome (AIDS) diagnosis for subjects who initially received zidovudine-, didanosine-, or zalcitabine-based therapy (ERA-I) and for those who initially received therapy regimens including lamivudine or stavudine (ERA-II).

Results: A total of 1178 patients (951 ERA-I, 227 ERA-II) were eligible. A total of 390 patients died (367 ERA-I, 23 ERA-II), yielding a crude mortality rate of 33.1%. ERA-I group subjects were almost twice as likely to die as ERA-II group subjects, with a mortality risk ratio of 1.86 (95% confidence interval [CI], 1.21 -2.86; P=.005). After adjusting for Pneumocystis carinii and Mycobacterium avium prophylaxis use, AIDS diagnosis, CD4+ cell count, sex, and age, ERA-I participants were 1.93 times (95% CI, 1.25-2.97; P=.003) more likely to die than ERA-II participants. Among patients without AIDS when treatment was started, ERA-I participants were 2.50 times (95% CI, 1.59-3.93; P<.001) more likely to progress to AIDS or death than ERA-II participants.

Conclusion: The HIV-infected individuals who received initial therapy with regimens including stavudine or lamivudine had significantly lower mortality and longer AIDS-free survival than those who received initial therapy with regimens limited to zidovudine, didanosine, and zalcitabine.