Effect of Highly Active Antiretroviral Therapy on Multiple AIDS-defining Illnesses among Male HIV Seroconverters

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Abstract
The effect of highly active antiretroviral therapy (HAART) on multiple acquired immunodeficiency syndrome (AIDS)–defining illnesses remains unclear. Between 1984 and 2005, 573 male human immunodeficiency virus seroconverters in four US urban centers were followed for a median of 9.7 years. During follow-up, 345, 113, 50, and 65 men incurred 0, 1, 2, and >2 AIDS-defining illnesses, respectively. The authors extend the Cox proportional hazards model to determine whether the effect of HAART, as measured by calendar periods, persists beyond the first AIDS-defining illness. After adjustment for race and age at seroconversion, the hazards of a first through third AIDS-defining illness in the HAART calendar period (beyond July 1995) were 0.31 (95% confidence interval (CI): 0.21, 0.46), 0.39 (95% CI: 0.22, 0.74), and 0.33 (95% CI: 0.14, 0.79), respectively, relative to the monotherapy and combination therapy reference calendar period (January 1990–July 1995) and therefore did not attenuate with the number of prior AIDS-defining illnesses (p for homogeneity = 0.83). After the authors averaged over multiple AIDS-defining illnesses, the hazard of an AIDS-defining illness in the HAART calendar period was 0.34 (95% CI: 0.25, 0.45) relative to the reference calendar period. HAART protects against initial and subsequent AIDS-defining illnesses, whose inclusion in analysis markedly increased the precision of the estimated hazard ratio.