title: Particulate air pollution, progression, and survival after myocardial infarction.
abstract: OBJECTIVE
  Several studies have examined the effect of particulate pollution (PM) on survival in general populations, but less is known about susceptible groups. Moreover, previous cohort studies have been cross-sectional and subject to confounding by uncontrolled differences between cities.
  
  
  METHODS
  We investigated whether PM was associated with progression of disease or reduced survival in a study of 196,000 persons from 21 U.S. cities discharged alive following an acute myocardial infarction (MI), using within-city between-year exposure to PM. We constructed city-specific cohorts of survivors of acute MI using Medicare data between 1985 and 1999, and defined three outcomes on follow-up: death, subsequent MI, and a first admission for congestive heart failure (CHF). Yearly averages of PM(10) (particulate matter with aerodynamic diameter < 10 microm) were merged to the individual annual follow-up in each city. We applied Cox's proportional hazard regression model in each city, with adjustment for individual risk factors. In the second stage of the analysis, the city-specific results were combined using a meta-regression.
  
  
  RESULTS
  We found significant associations with a hazard ratio for the sum of the distributed lags of 1.3 [95% confidence interval (CI), 1.2-1.5] for mortality, a hazard ratio of 1.4 (95% CI, 1.2-1.7) for a hospitalization for CHF, and a hazard ratio of 1.4 (95% CI, 1.1-1.8) for a new hospitalization for MI per 10 microg/m(3) PM(10).
  
  
  CONCLUSIONS
  This is the first long-term study showing a significant association between particle exposure and adverse post-MI outcomes in persons who survived an MI.
authors.affiliation: Department of Environmental Health, Harvard School of Public Health, Boston, Massachusetts 02215, USA. azanobet@hsph.harvard.edu
authors.forename: Antonella
authors.initials: A
authors.lastname: Zanobetti
authors.forename: Joel
authors.initials: J
authors.lastname: Schwartz
mesh_terms: D002947:Cities; D015331:Cohort Studies; D018450:Disease Progression; D006333:Heart Failure / Q000453:epidemiology*; D006801:Humans; D009203:Myocardial Infarction / Q000453:epidemiology* / Q000401:mortality / Q000503:physiopathology; D052638:Particulate Matter / Q000009:adverse effects*; D012008:Recurrence; D012044:Regression Analysis; D014481:United States / Q000453:epidemiology
chemical_list: D052638:Particulate Matter