Increasing age at HIV seroconversion from 18 to 40 years is associated with favorable virologic and immunologic responses to HAART

Background: Studies evaluating the effect of age on response to highly active antiretroviral therapy (HAART) have been limited by their inability to control for duration of human immunodeficiency virus (HIV) infection. We examined the effect of age at HIV seroconversion on response to HAART. Methods: A retrospective analysis of a longitudinal US military cohort of HIV-infected subjects. Time to and maintenance of viral Suppression, rate of CD4 cell increase, and rate of progression to acquired immunodeficiency syndrome or death were compared across age groups using time-to-event methods. Results: Five hundred sixty-three HIV-infected adults who seroconverted after January 1, 1996, and started HAART were included. Increasing age at seroconversion was significantly associated with faster time to viral Suppression (P = 0.002). Increasing age also correlated with duration Of Suppression, with a 35% reduction in risk of viral rebound for every 5-year increase in age above 18 years (hazard ratio: 0.65, 95% confidence interval 0.55 to 0.75). The rate of CD4 cell increase from 6 to 84 months post-HAART was significantly greater in those who seroconverted at older ages (P = 0.0002). Rates of progression to acquired immunodeficiency syndrome or death did not differ between groups. Conclusions: increasing age at seroconversion was associated with shorter time to and longer maintenance of viral suppression and a faster increase in CD4 cell count.