title: Comparison of transient associations of air pollution and AMI hospitalisation in two cities of Alberta, Canada, using a case-crossover design.
abstract: OBJECTIVE
  To investigate reproducibility of outcomes for short-term associations between ambient air pollutants and acute myocardial infarction (AMI) hospitalisation in 2 urban populations.
  
  
  METHODS
  Using a time-stratified design, we conducted independent case-crossover studies of AMI hospitalisation events over the period 1999-2010 in the geographically close and demographically similar cities of Calgary and Edmonton, Alberta, Canada. Patients with his/her first AMI hospitalisation event were linked with air pollution data from the National Ambient Pollution Surveillance database and meteorological data from the National Climatic Data Center database. Patients were further divided into subgroups to examine adjusted pollution effects. Effects of pollution levels with 0-3-day lag were modelled using conditional logistic regression and adjusted for daily average ambient temperature, dew point temperature and wind speed.
  
  
  METHODS
  Population-based studies in Calgary/Edmonton.
  
  
  METHODS
  12,066/10,562 first-time AMI hospitalisations in Calgary/Edmonton.
  
  
  METHODS
  Association (adjusted OR) between daily ambient air pollution levels and hospitalisation for AMI.
  
  
  RESULTS
  Among 600 potential air pollution effect variables investigated for the Calgary (Edmonton) population, only 1.17% (0.67%) was statistically significant by using the traditional 5% criterion. None of the effect variables were reproduced in the 2 cities, despite their geographic closeness (within 300 km of each other), and demographic and air pollution similarities.
  
  
  CONCLUSIONS
  Comparison of independent investigations of the effect of air pollution on risk of AMI hospitalisation in Calgary and Edmonton, Alberta, indicated that none of the air pollutants investigated-CO, NO, NO2, O3 and particulate matter (PM2.5)-showed consistent positive associations with increased risk of AMI hospitalisation.
authors.affiliation: School of Public Health, University of Alberta, Edmonton, Alberta, Canada.
authors.forename: Xiaoming
authors.initials: X
authors.lastname: Wang
authors.affiliation: School of Public Health, University of Alberta, Edmonton, Alberta, Canada.
authors.forename: Warren
authors.initials: W
authors.lastname: Kindzierski
authors.affiliation: Department of Medicine, Canadian Vigour Centre, University of Alberta, Edmonton, Alberta, Canada.
authors.forename: Padma
authors.initials: P
authors.lastname: Kaul
mesh_terms: D000208:Acute Disease; D000368:Aged; D000393:Air Pollutants / Q000032:analysis*; D000397:Air Pollution / Q000009:adverse effects*; D000416:Alberta / Q000453:epidemiology; D002947:Cities; D018592:Cross-Over Studies; D005260:Female; D006760:Hospitalization / Q000706:statistics & numerical data*; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000453:epidemiology*; D052638:Particulate Matter / Q000032:analysis*; D015203:Reproducibility of Results; D013997:Time Factors
chemical_list: D000393:Air Pollutants; D052638:Particulate Matter
keywords: acute mycardial infarction; air pollution; case-crossover; reproducibility