Primary covariates included age, sex, race/ethnicity, HIV, HCV antibody status, and HIV viral suppression. Age at blood draw was used as both a categorical (< 50, 50–64, and ≥ 65 years) and a continuous variable. Race was classified as African-American, White, and Hispanic/Other (includes other race not already classified). HIV+ status was confirmed during enrolment at the VA sites. HCV infection was defined based on a positive HCV antibody test, detectable HCV RNA or at least one inpatient and/or two outpatient ICD-9 code.40 Plasma HIV RNA of ≤ 500 copies/mL was used to define viral suppression. Additional covariates included smoking status (never/past/current), injection drug use in the past year (yes/no), and having at least some college education (yes/no), all of which were collected on the VACS surveys.
