title: Gender difference in HIV-1 RNA viral loads.
abstract: OBJECTIVE
  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 log(10) HIV-1 RNA copies/mL, P = 0.202; Athena: -0.005 log(10) copies/mL, P = 0.667; Plum: -0.072 log(10) copies/mL, P = 0.273). However, further investigation revealed that the gender effect depended on CD4 T-cell count. Women had consistently higher viral loads than men when CD4 T-cell counts were at most 50 cells/microL, and consistently lower viral loads than men when CD4 T-cell counts were greater than 350 cells/microL. 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.
authors.affiliation: Department of Infectious Disease Epidemiology, Faculty of Medicine, Imperial College London, London, UK. c.donnelly@imperial.ac.uk
authors.forename: C A
authors.initials: CA
authors.lastname: Donnelly
authors.forename: L M
authors.initials: LM
authors.lastname: Bartley
authors.forename: A C
authors.initials: AC
authors.lastname: Ghani
authors.forename: A M
authors.initials: AM
authors.lastname: Le Fevre
authors.forename: G P
authors.initials: GP
authors.lastname: Kwong
authors.forename: B J
authors.initials: BJ
authors.lastname: Cowling
authors.forename: A I
authors.initials: AI
authors.lastname: van Sighem
authors.forename: F
authors.initials: F
authors.lastname: de Wolf
authors.forename: R A
authors.initials: RA
authors.lastname: Rode
authors.forename: R M
authors.initials: RM
authors.lastname: Anderson
mesh_terms: D000328:Adult; D018791:CD4 Lymphocyte Count; D003625:Data Collection; D016208:Databases, Factual; D005260:Female; D015658:HIV Infections / Q000276:immunology / Q000821:virology*; D015497:HIV-1; D006801:Humans; D008297:Male; D012044:Regression Analysis; D017678:Sex Distribution; D018709:Statistics, Nonparametric; D014481:United States; D019562:Viral Load