Survival After Myocardial Infarction Is Associated With Elemental Carbon Exposure at Residence

Abstract

ISEE-634 Objective: To investigate the long-term effects of mobile source related air pollution on mortality, we conducted a cohort study of hospital survivors of acute myocardial infarction (AMI) in Worcester, MA, USA. Material and Methods: The study builds on an ongoing community-wide investigation examining changes over time in AMI incidence and hospital and long-term case-fatality rates of greater Worcester (MA) residents. Confirmed cases of AMI from all Central MA hospitals were included for 5 biennial study years of 1995 to 2003. Long-term survival status was ascertained through 2005. Patients’ residential addresses were geocoded. A validated spatiotemporal land use regression model for traffic-related air pollution was developed, which predicted local PM2.5 filter reflectance, a proxy measure of elemental carbon (EC), and traffic-related particulate pollution. The model was based on monitoring at 36 locations chosen to represent a range of exposures to traffic particles. The model's long-term predictions of EC by filter reflectance were computed at each residence. The effect of estimated EC on the risk of dying for subjects discharged after AMI was analyzed using a Cox Proportional Hazards model controlling for a variety of demographic, medical history, and clinical variables. Results: Of the 4055 patients with validated AMI, 58% were male and their mean age was 70 years. Long-term exposure to estimated EC ranged between 0.05 and 0.68 μg/m3 among the patients, with a mean of 0.35 μg/m3. We observed an increase in all cause mortality by 7.9% (95% confidence interval +0.0%–16.3%) per interquartile range increase in estimated EC (0.19 μg/m3). Conclusions: Our results suggest that long-term traffic-related particulate air pollution is associated with increased mortality in patients with acute coronary disease, with large effect sizes compared to PM2.5 cohort studies.