Effects of age and sex on immunological and virological responses to initial highly active antiretroviral therapy

Background: Highly active antiretroviral therapy (HAART) has increased longevity. Currently, women comprise >50% of HIV-infected individuals worldwide. It is not known if there are differences between the sexes in the immunological and virological responses to HAART across the age strata. Methods: Immunological reconstitution and virological response in the first 6 months of a first HAART regimen in two observational clinical HIV-infected cohorts were compared by both sex and age (≥50 vs. <50 years old). Results: A total of 246 individuals (28% women) were included in the study; 63 cases (≥50 years old) and 183 controls (<50 years old). Over two-thirds of patients had HIV RNA levels <400 HIV-1 RNA copies/ mL and CD4 count increases ≥50 cells/μL at 6 months from therapy initiation. There were no differences in immunological reconstitution across age and sex strata (P=0.81) and no differences in virological suppression, even after adjusting for type of HAART (P=0.68) or restricting the analysis to women only (P=0.81). These results suggest that younger and older women and men may have similar short-term initial HAART outcomes. Conclusions: Further evaluation of longer term clinical response to initial HAART regimen based on sex and age is indicated, especially with more efficacious and simplified antiretroviral regimens and the associated decrease in mortality.