Gender difference in HIV-1 RNA viral loads

Objectives: To test and characterize the dependence of viral load on gender in different countries and racial groups as a function of CD4 T-cell count. Methods: Plasma viral load data were analysed for > 30 000 HIV-infected patients attending clinics in the USA [HIV Insight™ (Cerner Corporation, Vienna, VA, USA) and Plum Data Mining LLC (East Meadow, NY, USA) databases] and the Netherlands (Athena database; HIV Monitoring Foundation, Amsterdam, Netherlands). Log-normal regression models were used to test for an effect of gender on viral load while adjusting for covariates and allowing the effect to depend on CD4 T-cell count. Sensitivity analyses were performed to test the robustness of conclusions to assumptions regarding viral loads below the lower limit of quantification (LLOQ). Results: After adjusting for covariates, women had (nonsignificantly) lower viral loads than men (HIV Insight™: - 0.053 log10 HIV-1 RNA copies/mL, P = 0.202; Athena: - 0.005 log10 copies/mL, P = 0.667; Plum: - 0.072 log10 copies/mL, P = 0.273). However, further investigation revealed that the gender effect d epended on CD4 T-cell count. Women had consistently higher viral loads than men when CD4 T-cell counts were at most 50 cells/μL, and consistently lower viral loads than men when CD4 T-cell counts were greater than 350 cells/μL. These effects were remarkably consistent when estimated independently for the racial groups with sufficient data available in the HIV Insight™ and Plum databases. Conclusions: The consistent relationship between gender-related differences in viral load and CD4 T-cell count demonstrated here explains the diverse findings previously published. © 2005 British HIV Association.