title: Impact of HIV-1 viral subtype on CD4+ T-cell decline and clinical outcomes in antiretroviral naive patients receiving universal healthcare.
abstract: OBJECTIVE
  The influence of viral subtype on the natural history of HIV is unclear and confounded by socioeconomic and host factors that vary between groups harboring different clades. We compared Canadians (clade B), with recent immigrants from Haiti (clade B) and sub-Saharan Africa (clades non-B) to determine whether there were differences in disease progression attributable to viral subtype.
  
  
  METHODS
  We conducted a retrospective cohort study in a universal healthcare setting between 1996 and 2007. The rate of CD4+ T-lymphocyte decline prior to initiation of antiretroviral therapy was determined in all participants with at least two CD4+ T-lymphocyte measures using mixed linear regression models. Time to first AIDS-defining illness was compared using adjusted Cox proportional hazards models.
  
  
  RESULTS
  Two hundred and eighty-nine Canadians, 44 Haitians, and 123 Africans were studied for a median of 260 days (2 days-11 years). Africans and Haitians were demographically and clinically similar. However, the adjusted slope of square root CD4+ T-lymphocyte decline was significantly lower in Africans [-0.04/year; 95% confidence interval (CI) = -0.08 to -0.003] compared with Canadians (-0.07/year; 95% CI = -0.11 to -0.03; P = 0.02), and Haitians (-0.10/year; 95% CI = -0.12 to -0.07; P = 0.001). Africans were also less likely to develop AIDS.
  
  
  CONCLUSIONS
  Despite having similar demographic, socioeconomic, and nutritional status to Haitians, Africans infected with non-B clade HIV had slower rates of disease progression compared with both Haitians and Canadians, with both groups being infected by the clade B virus. Our findings suggest that viral subtype may be an important predictor of HIV natural history in a developed medical setting.
authors.affiliation: Department of Medicine, Division of Infectious Diseases, Immunodeficiency Service, Montreal Chest Institute, McGill University Health Centre, Montreal, Quebec, Canada. marina.klein@mcgill.ca
authors.forename: Marina
authors.initials: M
authors.lastname: Keller
authors.forename: Ying
authors.initials: Y
authors.lastname: Lu
authors.forename: Richard G
authors.initials: RG
authors.lastname: Lalonde
authors.forename: Marina B
authors.initials: MB
authors.lastname: Klein
mesh_terms: D000293:Adolescent; D000328:Adult; D017954:Africa South of the Sahara / Q000208:ethnology; D044383:Black People / Q000706:statistics & numerical data; D018791:CD4 Lymphocyte Count; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology; D015986:Confounding Factors, Epidemiologic; D018450:Disease Progression; D005260:Female; D015658:HIV Infections / Q000208:ethnology / Q000276:immunology / Q000821:virology*; D015497:HIV-1 / Q000145:classification* / Q000235:genetics; D006205:Haiti / Q000208:ethnology; D006801:Humans; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D011792:Quebec / Q000453:epidemiology; D055815:Young Adult