The Veterans Aging Cohort Study (VACS) Index, a composite marker of disease severity among 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.
Participants included 655 HIV-infected persons followed for up to six years in cohort studies at the UCSD HIV Neurobehavioral Research Program (at baseline: Mean age=42.5; 83% male; 60% White; AIDS=67%; Median current CD4=346; 61% on 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.
Baseline VACS Index scores were not predictive of changes in global T-scores during the follow-up period (p=0.14). However, in time-dependent analyses adjusting for covariates, higher VACS Index scores were significantly associated with worse global and domain neurocognitive performance (ps<0.01), as well as increased risk for developing NCI in a subgroup who was neurocognitively normal at baseline (HR=1.17, p<0.001). 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<0.01) and middle groups (HR=1.76, p<0.01). 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.