title: Long-term trends in CD4 cell counts and impact of viral failure in individuals starting antiretroviral therapy: UK Collaborative HIV Cohort (CHIC) study.
abstract: OBJECTIVE
  The aim of the study was to describe trends in CD4 cell counts in HIV-infected patients after initiation of combination antiretroviral therapy (cART), according to CD4 cell count at initiation (baseline), and to quantify the implications of virological failure for these trends.
  
  
  METHODS
  Eligible participants from the UK Collaborative HIV Cohort (CHIC) were antiretroviralnaïve and started cART after 1997. Random effects were used to model CD4 cell count trends, accounting for multiple measurements within participants. We assessed whether CD4 cell count trends varied according to baseline CD4 cell count and separately in participants with and without post-cART virological failure. Effects of post-cART virological failure (>1000 HIV-1 RNA copies/mL) on subsequent CD4 cell counts were evaluated.
  
  
  RESULTS
  A total of 7069 participants were included in the analysis (median follow-up in all baseline CD4 cell count groups was ≥ 35 months). Among participants without virological failure ≥ 6 months after the start of cART, CD4 cell counts continued to increase up to 8 years, with little evidence that differences between baseline CD4 cell count groups diminished over time. Virological failure ≥ 6 months after the start of cART was associated with lower subsequent CD4 cell counts, with greater CD4 cell count reduction for more recent virological failure and higher viral load.
  
  
  CONCLUSIONS
  Post-cART CD4 cell counts are strongly related to pre-cART CD4 cell counts. CD4 cell count recovery is greatest in individuals who can avoid viral loads >1000 copies/mL while on cART.
authors.affiliation: University of Bristol, School of Social and Community Medicine, Bristol, UK St Mary's NHS Trust, London, UK. rachael.hughes@bristol.ac.uk
authors.forename: R A
authors.initials: RA
authors.lastname: Hughes
authors.forename: J A C
authors.initials: JA
authors.lastname: Sterne
authors.forename: J
authors.initials: J
authors.lastname: Walsh
authors.forename: L
authors.initials: L
authors.lastname: Bansi
authors.forename: R
authors.initials: R
authors.lastname: Gilson
authors.forename: C
authors.initials: C
authors.lastname: Orkin
authors.forename: T
authors.initials: T
authors.lastname: Hill
authors.forename: J
authors.initials: J
authors.lastname: Ainsworth
authors.forename: J
authors.initials: J
authors.lastname: Anderson
authors.forename: M
authors.initials: M
authors.lastname: Gompels
authors.forename: D
authors.initials: D
authors.lastname: Dunn
authors.forename: M A
authors.initials: MA
authors.lastname: Johnson
authors.forename: A N
authors.initials: AN
authors.lastname: Phillips
authors.forename: D
authors.initials: D
authors.lastname: Pillay
authors.forename: C
authors.initials: C
authors.lastname: Leen
authors.forename: P
authors.initials: P
authors.lastname: Easterbrook
authors.forename: B
authors.initials: B
authors.lastname: Gazzard
authors.forename: M
authors.initials: M
authors.lastname: Fisher
authors.forename: C A
authors.initials: CA
authors.lastname: Sabin
mesh_terms: D000328:Adult; D019380:Anti-HIV Agents / Q000627:therapeutic use*; D018791:CD4 Lymphocyte Count / Q000639:trends; D015331:Cohort Studies; D004359:Drug Therapy, Combination; D005260:Female; D005500:Follow-Up Studies; D015658:HIV Infections / Q000453:epidemiology / Q000276:immunology*; D015497:HIV-1 / Q000276:immunology*; D006801:Humans; D008297:Male; D011379:Prognosis; D012367:RNA, Viral / Q000187:drug effects / Q000276:immunology*; D006113:United Kingdom / Q000453:epidemiology; D019562:Viral Load / Q000276:immunology* / Q000639:trends
chemical_list: D019380:Anti-HIV Agents; D012367:RNA, Viral