Context: According to recent studies, women have lower plasma HIV RNA concentrations than men. However, these studies did not take into account the duration of HIV infection.
Objectives: To analyze the relationship between viral load and gender among individuals with known date of seroconversion.
Setting: Sixty infectious disease clinics in Italy.
Design: Cross-sectional analysis of data collected at enrollment in a cohort study.
Participants: Injecting drug users and heterosexual contacts naive to antiretroviral therapy at enrollment (245 men; 170 women).
Main outcome measures: Plasma HIV RNA concentrations, measured using quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) or signal amplification b-DNA assays before antiretroviral therapy.
Results: Plasma HIV RNA concentrations were similar by age and exposure category (p =.80 and p =.39, respectively). Median viral load among women was roughly half that of men (p =.002). The association between viral load and gender remained significant after fitting a two-way analysis of variance (p =.03) and after adjusting for CD4 count, modality of HIV transmission, and age at enrollment in a regression model. Viral load was 0.27 log10 copies/ml (95% confidence interval, 0.05-0.40; p =.01) lower in women (i.e., 50% lower in the raw scale).
Conclusions: Plasma HIV RNA concentrations were found to be lower among women, even when considering the duration of HIV infection. Compared with men, it is possible women should be given highly aggressive antiretroviral therapy at lower HIV-RNA concentrations.