Predictive accuracy of the Veterans Aging Cohort Study index for mortality with HIV infection: a North American cross cohort analysis

J Acquir Immune Defic Syndr. 2013 Feb 1;62(2):149-63. doi: 10.1097/QAI.0b013e31827df36c.

Abstract

Background: By supplementing an index composed of HIV biomarkers and age (restricted index) with measures of organ injury, the Veterans Aging Cohort Study (VACS) index more completely reflects risk of mortality. We compare the accuracy of the VACS and restricted indices (1) among subjects outside the Veterans Affairs Healthcare System, (2) more than 1-5 years of prior exposure to antiretroviral therapy (ART), and (3) within important patient subgroups.

Methods: We used data from 13 cohorts in the North American AIDS Cohort Collaboration (n = 10, 835) limiting analyses to HIV-infected subjects with at least 12 months exposure to ART. Variables included demographic, laboratory (CD4 count, HIV-1 RNA, hemoglobin, platelets, aspartate and alanine transaminase, creatinine, and hepatitis C status), and survival. We used C-statistics and net reclassification improvement (NRI) to test discrimination varying prior ART exposure from 1 to 5 years. We then combined Veterans Affairs Healthcare System (n = 5066) and North American AIDS Cohort Collaboration data, fit a parametric survival model, and compared predicted to observed mortality by cohort, gender, age, race, and HIV-1 RNA level.

Results: Mean follow-up was 3.3 years (655 deaths). Compared with the restricted index, the VACS index showed greater discrimination (C-statistics: 0.77 vs. 0.74; NRI: 12%; P < 0.0001). NRI was highest among those with HIV-1 RNA <500 copies per milliliter (25%) and age ≥50 years (20%). Predictions were similar to observed mortality among all subgroups.

Conclusions: VACS index scores discriminate risk and translate into accurate mortality estimates over 1-5 years of exposure to ART and for diverse patient subgroups from North American.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Age Factors
  • Alanine Transaminase / blood
  • Anti-Retroviral Agents / therapeutic use
  • Aspartate Aminotransferases / blood
  • Biomarkers / blood*
  • CD4 Lymphocyte Count
  • Cohort Studies
  • Creatinine / blood
  • Female
  • HIV Infections / drug therapy
  • HIV Infections / ethnology
  • HIV Infections / immunology
  • HIV Infections / mortality*
  • HIV-1 / genetics
  • HIV-1 / immunology
  • Hemoglobins / metabolism
  • Hepatitis C / blood
  • Hepatitis C / mortality
  • Humans
  • Kaplan-Meier Estimate
  • Male
  • Middle Aged
  • North America / epidemiology
  • Platelet Count
  • Predictive Value of Tests
  • RNA, Viral / blood
  • Risk Assessment / methods
  • Sex Factors

Substances

  • Anti-Retroviral Agents
  • Biomarkers
  • Hemoglobins
  • RNA, Viral
  • Creatinine
  • Aspartate Aminotransferases
  • Alanine Transaminase

Grant support