Covariates

Sociodemographic factors measured at baseline included race/ethnicity, age, sex, smoking status, education years, and income. Race/ethnicity (African American, white or other race) was self-reported. Age, sex and smoking status (never, past or current) were self-reported. Body mass index (BMI) was measured by physical exam and was calculated from measured height and weight (weight (kg)/height (m)²) was classified into normal weight (BMI 18.5–24.9), overweight (BMI 25.0–29.9), or obese (BMI ≥30). Waist circumference was measured at the umbilicus twice and the average taken. sAGE levels were examined by smoking status and found to be equivalent in current and past smokers. The smoking status variable was restructured for further analysis into never smoked versus current and past smoking.