Albumin, white blood cell count, and body mass index improve discrimination of mortality in HIV-positive individuals

Janet P Tate, Jonathan Sterne, Amy Justice, Veterans Aging Cohort Study (VACS) and The Antiretroviral Therapy Cohort Collaboration (ART-CC)

Research output: Contribution to journalArticle (Academic Journal)

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Abstract

OBJECTIVE: Despite viral suppression and immune response on antiretroviral therapy, people with HIV infection experience excess mortality compared with uninfected individuals. The Veterans Aging Cohort Study (VACS) Index incorporates clinical biomarkers of general health with age, CD4 cell count, and HIV-1 RNA to discriminate mortality risk in a variety of HIV-positive populations. We asked whether additional biomarkers further enhance discrimination. 

DESIGN AND METHODS: Using patients from VACS for development and from the Antiretroviral Therapy Cohort Collaboration (ART-CC) for validation, we obtained laboratory values from a randomly selected visit from 2000 to 2014, at least 1 year after antiretroviral therapy initiation. Patients were followed for 5-year, all-cause mortality through September 2016. We fitted Cox models with established predictors and added new predictors based on model fit and Harrell's c-statistic. We converted all variables to continuous functional forms and selected the best model (VACS Index 2.0) for validation in ART-CC patients. We compared discrimination using c-statistics and Kaplan-Meier plots.

RESULTS: Among 28 390 VACS patients and 12 109 ART-CC patients, 7293 and 722 died, respectively. Nadir CD4, CD8, and CD4 : CD8 ratio did not improve discrimination. Addition of albumin, white blood count, and BMI, improved c-statistics in VACS from 0.776 to 0.805 and in ART-CC from 0.800 to 0.831. Results were robust in all nine ART-CC cohorts, all lengths of follow-up and all subgroups.

 CONCLUSION: VACS Index 2.0, adding albumin, white blood count, and BMI to version 1.0 and using continuous variables, provides improved discrimination and is highly transportable to external settings.

Original languageEnglish
Pages (from-to)903-912
Number of pages10
JournalAIDS
Volume33
Issue number5
Early online date14 Jan 2019
DOIs
Publication statusPublished - 1 Apr 2019

Keywords

  • validation
  • prognostic index
  • mortality
  • comorbidity
  • cohort study
  • albumin
  • BMI

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