Residential Exposure to Traffic-Related Air Pollution and Survival after Heart Failure

BACKGROUND Although patients with heart failure (HF) have been identified as particularly susceptible to the acute effects of air pollution, the effects of long-term exposure to air pollution on patients with this increasingly prevalent disease are largely unknown. OBJECTIVE This study was designed to examine the mortality risk associated with residential exposure to traffic-related air pollution among HF patients. METHODS A total of 1,389 patients hospitalized with acute HF in greater Worcester, Massachusetts, during 2000 were followed for survival through December 2005. We used daily traffic within 100 and 300 m of residence as well as the distance from residence to major roadways and to bus routes as proxies for residential exposure to traffic-related air pollution. We assessed mortality risks for each exposure variable using Cox proportional hazards models adjusted for prognostic factors. RESULTS After the 5-year follow-up, only 334 (24%) subjects were still alive. An interquartile range increase in daily traffic within 100 m of home was associated with a mortality hazard ratio (HR) of 1.15 [95% confidence interval (CI), 1.05-1.25], whereas for traffic within 300 m this association was 1.09 (95% CI, 1.01-1.19). The mortality risk decreased with increasing distance to bus routes (HR = 0.88; 95% CI, 0.81-0.96) and was larger for those living within 100 m of a major roadway or 50 m of a bus route (HR = 1.30; 95% CI, 1.13-1.49). Adjustment for area-based income and educational level slightly attenuated these associations. CONCLUSIONS Residential exposure to traffic-related air pollution increases the mortality risk after hospitalization with acute HF. Reducing exposure to traffic-related emissions may improve the long-term prognosis of HF patients.