title: CD4 cell responses to combination antiretroviral therapy in patients starting therapy at high CD4 cell counts.
abstract: OBJECTIVE
  To examine CD4 cell responses to combination antiretroviral therapy (cART) in patients enrolled in the Australian HIV Observational Database who commenced cART at CD4 cell counts >350 cells per microliter.
  
  
  METHODS
  CD4 cell counts were modelled using random effects, repeated measurement models in 432 HIV-infected adults from Australian HIV Observational Database who commenced their first cART regimen and had a baseline CD4 count >350 cells per microliter. Using published AIDS and/or death incidence rates combined with the data summarized by time and predicted CD4 cell count, we calculated the expected reduction in risk of an event for different starting baseline CD4 strata.
  
  
  RESULTS
  Mean CD4 counts increased above 500 cells per microliter in all baseline CD4 strata by 12 months (means of 596, 717, and 881 cells/μL in baseline CD4 strata 351-500, 501-650, and >650 cells/μL, respectively) and after 72 months since initiating cART, mean CD4 cell counts (by increasing baseline CD4 strata) were 689, 746, 742 cells per microliter. The expected reduction in risk of mortality for baseline CD4 counts >650 cells per microliter relative to 351-500 cells per microliter was approximately 8%, an absolute risk reduction 0.33 per 1000 treated patient-years.
  
  
  CONCLUSIONS
  Patients starting cART at high CD4 cell counts (>650 cells/μL) tend to maintain this immunological level over 6 years of follow-up. Patients starting from 351 to 500 CD4 cells per microliter achieve levels of >650 cells per microliter after approximately 3 years of cART. Initiating cART with a baseline CD4 count 501-650 or >650 cells per microliter relative to 351-500 cells per microliter indicated a minimal reduction in risk of AIDS incidence and/or death.
authors.affiliation: The Kirby Institute (formally National Centre in HIV Epidemiology and Clinical Research), University of New South Wales, Darlinghurst, New South Wales 2010, Australia. swright@kirby.unsw.edu.au
authors.forename: Stephen T
authors.initials: ST
authors.lastname: Wright
authors.forename: Andrew
authors.initials: A
authors.lastname: Carr
authors.forename: Ian
authors.initials: I
authors.lastname: Woolley
authors.forename: Michelle
authors.initials: M
authors.lastname: Giles
authors.forename: Jennifer
authors.initials: J
authors.lastname: Hoy
authors.forename: David A
authors.initials: DA
authors.lastname: Cooper
authors.forename: Matthew G
authors.initials: MG
authors.lastname: Law
mesh_terms: D000328:Adult; D019380:Anti-HIV Agents / Q000008:administration & dosage* / Q000627:therapeutic use*; D018791:CD4 Lymphocyte Count; D004334:Drug Administration Schedule; D004359:Drug Therapy, Combination; D005260:Female; D015658:HIV Infections / Q000188:drug therapy* / Q000276:immunology; D006801:Humans; D008297:Male; D008875:Middle Aged
chemical_list: D019380:Anti-HIV Agents