title: Absolute count and percentage of CD4+ lymphocytes are independent predictors of disease progression in HIV-infected persons initiating highly active antiretroviral therapy.
abstract: BACKGROUND
  Highly active antiretroviral therapy (HAART) is recommended when the absolute CD4(+) T lymphocyte count is <200 cells/mm(3), and it should be considered when that count is > or =200, although the optimal timing when it is > or =200 is unclear. Because preliminary data had suggested that a low CD4(+) T lymphocyte percentage (%CD4) is associated with disease progression in persons initiating HAART who have a higher absolute CD4, we sought to further characterize the predictive utility of %CD4.
  
  
  METHODS
  We conducted an observational study of persons in Collaborations in HIV Outcomes Research/US cohort who initiated their first HAART regimen between 1997 and 2004, received > or =30 days of therapy, and had baseline values of absolute CD4, %CD4, and HIV-1 RNA. Cox proportional-hazards models determined associations between %CD4 and disease progression (to either a new AIDS-defining event [ADE] or death).
  
  
  RESULTS
  Of 1891 persons, 11% were female and 18% were African American; the median age was 38 years. Median follow-up was 55 months (interquartile range, 23-83 months), and 468 (25%) had disease progression. Multivariable analysis including age, race, sex, HIV-1 RNA, prior antiretroviral therapy, probable route of infection, prior ADE, absolute CD4, and %CD4 was performed; prior ART (P<.0001), injection-drug use (P=.04), lower absolute CD4 (P=.002), and lower %CD4 (P=.002) predicted disease progression.
  
  
  CONCLUSIONS
  %CD4 at initiation of the first HAART regimen predicted disease progression independent of absolute CD4; %CD4 may be used to determine the timing of HAART.
authors.affiliation: Department of Medicine, Division of Infectious Diseases, Vanderbilt University School of Medicine, Nashville, TN 37203, USA. todd.hulgan@vanderbilt.edu
authors.forename: Todd
authors.initials: T
authors.lastname: Hulgan
authors.forename: Bryan E
authors.initials: BE
authors.lastname: Shepherd
authors.forename: Stephen P
authors.initials: SP
authors.lastname: Raffanti
authors.forename: Jennifer S
authors.initials: JS
authors.lastname: Fusco
authors.forename: Robin
authors.initials: R
authors.lastname: Beckerman
authors.forename: Gema
authors.initials: G
authors.lastname: Barkanic
authors.forename: Timothy R
authors.initials: TR
authors.lastname: Sterling
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D044966:Anti-Retroviral Agents / Q000627:therapeutic use*; D023241:Antiretroviral Therapy, Highly Active; D015415:Biomarkers / Q000097:blood; D018791:CD4 Lymphocyte Count; D015331:Cohort Studies; D018450:Disease Progression; D005260:Female; D015658:HIV Infections / Q000175:diagnosis / Q000188:drug therapy* / Q000276:immunology* / Q000821:virology; D015497:HIV-1 / Q000235:genetics / Q000302:isolation & purification; D006801:Humans; D008297:Male; D008875:Middle Aged; D019370:Observation; D016016:Proportional Hazards Models; D012367:RNA, Viral / Q000097:blood; D013997:Time Factors; D016896:Treatment Outcome; D014481:United States
chemical_list: D044966:Anti-Retroviral Agents; D015415:Biomarkers; D012367:RNA, Viral