Impact of gender on response to highly active antiretroviral therapy in HIV-1 infected patients: a nationwide population-based cohort study

BACKGROUND Impact of gender on time to initiation, response to and risk of modification of highly active antiretroviral therapy (HAART) in HIV-1 infected individuals is still controversial. METHODS From a nationwide cohort of Danish HIV infected individuals we identified all heterosexually infected women (N=587) and heterosexually infected men (N=583) with no record of Hepatitis C infection diagnosed with HIV after 1 January 1997. Among these subjects, 473 women (81%) and 435 men (75%) initiated HAART from 1 January 1997 to 31 December 2009. We used Cox regression to calculate hazard ratio (HR) for time to initiation of HAART, Poisson regression to assess incidence rate ratios (IRR) of risk of treatment modification the first year, logistic regression to estimate differences in the proportion with an undetectable viral load, and linear regression to detect differences in CD4 count at year 1, 3 and 6 after start of HAART. RESULTS At initiation of HAART, women were younger, predominantly of Black ethnicity and had a higher CD4 count (adjusted p=0.026) and lower viral load (adjusted p=0.0003). When repeating the analysis excluding pregnant women no difference was seen in CD4 counts (adjusted p=0.21). We observed no delay in time to initiation of HAART in women compared to men (HR 0.91, 95% CI 0.79-1.06). There were no gender differences in risk of treatment modification of the original HAART regimen during the first year of therapy for either toxicity (IRR 0.97 95% CI 0.66-1.44) or other/unknown reasons (IRR 1.18 95% CI 0.76-1.82). Finally, CD4 counts and the risk of having a detectable viral load at 1, 3 and 6 years did not differ between genders. CONCLUSIONS In a setting with free access to healthcare and HAART, gender does neither affect time from eligibility to HAART, modification of therapy nor virological and immunological response to HAART. Differences observed between genders are mainly attributable to initiation of HAART in pregnant women.