All analyses included self-reported gender, race, and age at time of survey in 5-year bins, region of country, survey administration year, health and wellness factors, and socioeconomic factors. Health and wellness factors included current smoking status (never smoker, former smoker, and current smoker categorized into cigarettes smoked per day (CPD) ≤ 10, CPD 11–20, CPD 21–30, CPD > 30), perceived health status (on a 4-level scale), exercise level (quartiles), and medical comorbidities (indicator variables for self-reported history of each of the following: AIDS, cancer, chronic obstructive pulmonary disease (COPD), diabetes mellitus, heart failure, liver disease, myocardial infarction, peripheral vascular disease, peptic ulcer disease, and rheumatoid arthritis). These comorbidities were chosen based on their inclusion in a clinical comorbidity index (Deyo, Cherkin and Ciol 1992). Socioeconomic factors included educational category (no degree, high school degree, some college, bachelor’s degree or higher), current employment status (never worked, worked in the last week, didn’t work in the past 12 months, didn’t work in the last week but worked in the past 12 months), and whether the household received food stamps in the last calendar year.
