title: The Veterans Aging Cohort Study (VACS) Index and Neurocognitive Change: A Longitudinal Study.
abstract: BACKGROUND
  The Veterans Aging Cohort Study (VACS) Index, a composite marker of disease severity among human immunodeficiency virus (HIV)-infected persons, has been associated with concurrent risk for neurocognitive impairment (NCI). The present study examined whether the VACS Index predicts longitudinal neurocognitive change.
  
  
  METHODS
  Participants included 655 HIV-infected persons followed for up to 6 years in cohort studies at the University of California, San Diego, HIV Neurobehavioral Research Program (mean age at baseline, 42.5 years; 83% male; 60% white; AIDS in 67%; median current CD4(+) T-cell count, 346/μL; 61% receiving antiretroviral therapy). The VACS Index was calculated through standard methods. Participants completed a comprehensive neurocognitive battery. Neurocognitive status was plotted over time using demographically and practice-adjusted global and domain T scores. NCI was defined by global deficit scores derived from T scores.
  
  
  RESULTS
  Baseline VACS Index scores were not predictive of changes in global T scores during the follow-up period (P = .14). However, in time-dependent analyses adjusting for covariates, higher VACS Index scores were significantly associated with worse global and domain neurocognitive performance (Ps < .01), as well as increased risk for developing NCI in a subgroup of persons who were neurocognitively normal at baseline (hazard ratio [HR], 1.17; P < .001). We categorized VACS Index scores by quartiles and found that the upper-quartile group was significantly more likely to develop NCI than the lower quartile (HR, 2.16; P < .01) and middle groups (HR, 1.76; P < .01).
  
  
  CONCLUSIONS
  Changes in VACS Index scores correspond to changes in neurocognitive function. HIV-infected persons with high VACS Index scores are at increased risk for decline and incident NCI. The VACS Index shows promise as a tool for identifying HIV-infected persons at risk for NCI.
authors.affiliation: Department of Psychiatry.
authors.forename: María J
authors.initials: MJ
authors.lastname: Marquine
authors.affiliation: Department of Psychiatry.
authors.forename: Jessica L
authors.initials: JL
authors.lastname: Montoya
authors.affiliation: Department of Psychiatry.
authors.forename: Anya
authors.initials: A
authors.lastname: Umlauf
authors.affiliation: Psychology Department, University of Alabama, Birmingham.
authors.forename: Pariya L
authors.initials: PL
authors.lastname: Fazeli
authors.affiliation: Department of Psychiatry.
authors.forename: Ben
authors.initials: B
authors.lastname: Gouaux
authors.affiliation: Department of Psychiatry.
authors.forename: Robert K
authors.initials: RK
authors.lastname: Heaton
authors.affiliation: Department of Neurosciences.
authors.forename: Ronald J
authors.initials: RJ
authors.lastname: Ellis
authors.affiliation: Department of Medicine, University of California, San Diego.
authors.forename: Scott L
authors.initials: SL
authors.lastname: Letendre
authors.affiliation: Department of Psychiatry.
authors.forename: Igor
authors.initials: I
authors.lastname: Grant
authors.affiliation: Department of Psychiatry.
authors.forename: David J
authors.initials: DJ
authors.lastname: Moore
mesh_terms: D015526:AIDS Dementia Complex / Q000453:epidemiology* / Q000503:physiopathology*; D000328:Adult; D000375:Aging / Q000502:physiology*; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D014728:Veterans / Q000523:psychology* / Q000706:statistics & numerical data*
keywords: HIV; biomarkers; cognitive impairment