After adjustment for cardiovascular risk factors and despite higher mortality, those with HIV (HIV+) have a greater risk of acute myocardial infarction (AMI) than uninfected individuals. We modeled the association of baseline, time-updated, and cumulative measures of HIV-1 RNA, CD4 count, and the VACS Index on AMI incidence and mortality.
We included HIV+ starting combination antiretroviral therapy (cART) in the Veterans Aging Cohort Study (VACS) from 1996-2012. We fitted multivariable proportional hazards models for baseline, time-updated and cumulative measures of HIV-1 RNA, CD4 counts, and the VACS Index. We used the trapezoidal rule to build cumulative measures: viremia copy-years, CD4-years, and VACS Index score-years, captured 180 days after cART initiation until AMI, death, last clinic visit or 9/30/2012. The primary outcomes were incident AMI (Medicaid, Medicare and Veterans Affairs ICD-9 codes) and death.
8,168 HIV+ (53,861 person-years) were analyzed with 196 incident AMIs and 1,710 deaths. Controlling for known cardiovascular risk factors, six of the nine metrics predicted AMI and all metrics predicted mortality. Time-updated VACS Index had the lowest Akaike information criterion among all models for both outcomes. A time-updated VACS Index score of 55+ was associated with a HR of 3.31 (95% CI: 2.11-5.20) for AMI and a HR of 31.77 (95% CI: 26.17-38.57) for mortality.
Time-updated VACS Index provided better AMI and mortality prediction than CD4 count and HIV-1 RNA suggesting that current health determines risk more than prior history and that risk assessment can be improved by biomarkers of organ injury.