Management of HIV through Health Preserving Life Styles

The VACS Index Predicts Mortality In A Young, Healthy HIV Population Starting Highly Active Antiretroviral Therapy

Bebu, Ionut PhD; Tate, Janet ScD; Rimland, David MD; Mesner, Octavio MS; Macalino, Grace E. PhD; Ganesan, Anuradha MD; Okulicz, Jason F. MD; Bavaro, Mary MD; Weintrob, Amy C. MD; Justice, Amy C. MD, PhD; Agan, Brian K. MD; the Infectious Disease Clinical Research Program HIV Working Group

Published Ahead-of-Print
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Abstract

Background: The Veterans Aging Cohort Study (VACS) Index is a weighted combination of age and eight clinical variables. It has been well correlated with all-cause mortality among HIV- infected patients. The U.S. Military HIV Natural History Study (NHS) cohort provides a different validation population profile, being younger and healthier. A significant portion of the US HIV population is similarly composed, so evaluation of the VACS Index in this population is of great interest.
Methods: NHS subjects have medical history and laboratory data collected at six month visits. We performed an external validation of the VACS Index in the NHS evaluating correlation, discrimination, and calibration for all-cause mortality following HAART initiation (HI). We then tested whether combining longitudinal VACS Index values at different time points improves prediction of mortality.
Results: The VACS Index at one year after HI was well correlated with all-cause mortality (Harrell's c-statistic 0.78), provided good discrimination (log-rank p <0.05), and was marginally well calibrated using Brier score. Accounting for VACS Index at HI and 6 months after HI significantly improved a standard model including only the VACS Index at 1 year after HI (Net Reclassification Improvement=25.2%, 10.9-48.9% 95% CI).
Conclusions: The VACS Index was well correlated and provided good discrimination with respect to all-cause mortality among HAART initiating subjects in the NHS. Moderate overprediction of mortality in this young, healthy population suggests minor recalibration could improve fit among similar patients. Considering VACS Index at HI and 6 months improved outcome prediction and allowed earlier risk assessment.
(C) 2013 by Lippincott Williams & Wilkins

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