Abstract Body (Do not enter title and authors here): Introduction
Exposure to ambient air pollution may increase the risk of cardiovascular disease events and mortality, but prior publications have primarily included administrative cohorts with outcomes that have not been individually reviewed and with air pollution estimates created without cohort-specific exposure monitoring. Multi-Ethnic Study of Atherosclerosis (MESA) is a multi-site cohort study designed specifically to prospectively collect and adjudicate cardiovascular disease (CVD) events. MESA Air recruited additional participants into sub-cohorts for enhanced air pollution variation and sample size.
Research Question
The aim of this analysis was to characterize the relationship between long-term exposure to nitrogen dioxide (NO₂) and fine particulate matter (PM_2.5) and all-cause mortality and CVD events.
Methods
Air pollution exposure was assessed using address history with a purpose-built exposure model incorporating cohort-specific monitoring including measurement and validation at participant homes. We used Cox models to assess the risk of rolling 2-year average exposures on all cause-mortality and on a composite CVD endpoint (definite angina, probable angina with revascularization, myocardial infarction, atherosclerosis or other CVD death, resuscitated cardiac arrest, and stroke). Models were stratified for baseline hazard by age, sub-cohort, and recruitment year and were additionally adjusted for age, sex, race/ethnicity, field center, smoking/second-hand smoke, pack-years, physical activity, education, income, neighborhood socioeconomic status, and statin use.
Results
MESA Air participants were aged 44-87 years at enrollment between 2000 and 2007; follow-up averaged 14 years. 6,915 participants had follow-up for events, NO₂ exposure, and covariate information. We observed 1,442 deaths and 985 CVD events. The interquartile range over all 2-year averages was 10.5-23.1 ppb for NO₂ and 10.1-14.9 µ/m³ for PM_2.5. The adjusted hazard ratio (aHR) for a 10 ppb increment in NO₂ was 1.38 (95% CI: 1.17, 1.64) for all-cause mortality and 1.16 (95% CI: 0.95, 1.42) for incident CVD events. The aHR for a 5 µg/m³ increment in PM_2.5 was 1.20 (95% CI: 0.99, 1.46) for all-cause mortality and 1.15 (95% CI: 0.95, 1.39) for incident CVD events
Conclusions
These results add to growing literature demonstrating an association between air pollution exposure, mortality, and CVD in a cohort with well-characterized clinical endpoints and cohort-specific exposure assessment.