title: CD4 percentage is an independent predictor of survival in patients starting antiretroviral therapy with absolute CD4 cell counts between 200 and 350 cells/microL.
abstract: OBJECTIVE
  To determine the prognostic value of baseline CD4 percentage in terms of patient survival in comparison to absolute CD4 cell counts for HIV-positive patients initiating highly active antiretroviral therapy (HAART).
  
  
  METHODS
  A population-based cohort study of 1,623 antiretroviral therapy-naïve HIV-positive individuals who initiated HAART between 1 August 1996 and 30 June 2002 was conducted. Cumulative mortality rates were estimated using Kaplan-Meier methods. Cox proportional hazards regression was used to model the effect of baseline CD4 strata and CD4 percentage strata and other prognostic variables on survival. A subgroup analysis was conducted on 417 AIDS-free subjects with baseline CD4 counts between 200 and 350 cells/microL.
  
  
  RESULTS
  In multivariate models, low CD4 percentages were associated with increased risk of death [CD4%<5, relative hazard (RH)=4.46; CD4% 5-14, RH=2.43; P<0.01 for both] when compared with those subjects with an initial CD4 fraction of 15% or greater, but had less predictive value than absolute CD4 counts. In subgroup analyses where absolute CD4 strata were not associated with mortality, a baseline CD4 fraction below 15% [RH=2.71; 95% confidence interval (CI) 1.20-6.10], poor adherence to therapy and baseline viral load >100,000 HIV-1 RNA copies/mL were associated with an increased risk of death.
  
  
  CONCLUSIONS
  CD4 percentages below 15% are independent predictors of mortality in AIDS-free patients starting HAART, including those with CD4 counts between 200 and 350 cells/microL. CD4 percentage should be considered for inclusion in guidelines used to determine when to start therapy.
authors.affiliation: BC Centre for Excellence in HIV/AIDS, Vancouver, British Columbia, Canada. dmoore@cfenet.ubc.ca
authors.forename: D M
authors.initials: DM
authors.lastname: Moore
authors.forename: R S
authors.initials: RS
authors.lastname: Hogg
authors.forename: B
authors.initials: B
authors.lastname: Yip
authors.forename: K
authors.initials: K
authors.lastname: Craib
authors.forename: E
authors.initials: E
authors.lastname: Wood
authors.forename: J S G
authors.initials: JS
authors.lastname: Montaner
mesh_terms: D000328:Adult; D023241:Antiretroviral Therapy, Highly Active; D018791:CD4 Lymphocyte Count; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D005260:Female; D015658:HIV Infections / Q000188:drug therapy / Q000276:immunology* / Q000401:mortality*; D015497:HIV-1; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D011237:Predictive Value of Tests; D016016:Proportional Hazards Models; D016019:Survival Analysis