Mean differences (95% CI) in IMT at baseline and in IMT progression over time associated with PM2.5 concentrations prior to baseline and averaged over follow-up, with and without control for metropolitan area.

Minimal adjustment included age, sex, and race/ethnicity. Moderately adjustment added control for education, a neighborhood socio-economic score (derived from census tract level data on education, occupation, median home values, and median household income), adiposity (1/height, 1/height2, weight, waist, and 1/hip), and pack-years at baseline as well as a time-varying smoking status. Main models further adjusted for HDL, total cholesterol, statin use, diabetes mellitus (using the 2003 ADA fasting criteria algorithm), systolic blood pressure, diastolic blood pressure, hypertensive diagnosis, and hypertensive medications. In sensitivity analyses, we tested an extended model that also included physical activity, second-hand smoke exposures, alcohol use, C-reactive protein, creatinine, fibrinogen, occupation, and neighborhood noise among a smaller subset of the population with complete data.