title: Public health importance of triggers of myocardial infarction: a comparative risk assessment.
abstract: BACKGROUND
  Acute myocardial infarction is triggered by various factors, such as physical exertion, stressful events, heavy meals, or increases in air pollution. However, the importance and relevance of each trigger are uncertain. We compared triggers of myocardial infarction at an individual and population level.
  
  
  METHODS
  We searched PubMed and the Web of Science citation databases to identify studies of triggers of non-fatal myocardial infarction to calculate population attributable fractions (PAF). When feasible, we did a meta-regression analysis for studies of the same trigger.
  
  
  RESULTS
  Of the epidemiologic studies reviewed, 36 provided sufficient details to be considered. In the studied populations, the exposure prevalence for triggers in the relevant control time window ranged from 0.04% for cocaine use to 100% for air pollution. The reported odds ratios (OR) ranged from 1.05 to 23.7. Ranking triggers from the highest to the lowest OR resulted in the following order: use of cocaine, heavy meal, smoking of marijuana, negative emotions, physical exertion, positive emotions, anger, sexual activity, traffic exposure, respiratory infections, coffee consumption, air pollution (based on a difference of 30 μg/m3 in particulate matter with a diameter <10 μm [PM10]). Taking into account the OR and the prevalences of exposure, the highest PAF was estimated for traffic exposure (7.4%), followed by physical exertion (6.2%), alcohol (5.0%), coffee (5.0%), a difference of 30 μg/m3 in PM10 (4.8%), negative emotions (3.9%), anger (3.1%), heavy meal (2.7%), positive emotions (2.4%), sexual activity (2.2%), cocaine use (0.9%), marijuana smoking (0.8%) and respiratory infections (0.6%). Interpretation In view of both the magnitude of the risk and the prevalence in the population, air pollution is an important trigger of myocardial infarction, it is of similar magnitude (PAF 5-7%) as other well accepted triggers such as physical exertion, alcohol, and coffee. Our work shows that ever-present small risks might have considerable public health relevance.
  
  
  BACKGROUND
  The research on air pollution and health at Hasselt University is supported by a grant from the Flemish Scientific Fund (FWO, Krediet aan navorsers/G.0873.11), tUL-impulse financing, and bijzonder onderzoeksfonds (BOF) and at the Katholieke Universiteit Leuven by the sustainable development programme of BELSPO (Belgian Science Policy).
authors.affiliation: Centre for Environmental Sciences, Hasselt University, Diepenbeek, Belgium. tim.nawrot@uhasselt.be
authors.forename: Tim S
authors.initials: TS
authors.lastname: Nawrot
authors.forename: Laura
authors.initials: L
authors.lastname: Perez
authors.forename: Nino
authors.initials: N
authors.lastname: Künzli
authors.forename: Elke
authors.initials: E
authors.lastname: Munters
authors.forename: Benoit
authors.initials: B
authors.lastname: Nemery
mesh_terms: D000328:Adult; D000368:Aged; D000397:Air Pollution / Q000009:adverse effects*; D002188:Cannabis / Q000009:adverse effects; D003042:Cocaine / Q000009:adverse effects; D003069:Coffee / Q000009:adverse effects; D004644:Emotions; D004781:Environmental Exposure / Q000009:adverse effects*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000453:epidemiology* / Q000209:etiology*; D016017:Odds Ratio; D052638:Particulate Matter / Q000009:adverse effects*; D005082:Physical Exertion; D015995:Prevalence; D011634:Public Health / Q000706:statistics & numerical data* / Q000639:trends; D012141:Respiratory Tract Infections / Q000150:complications; D018570:Risk Assessment; D012307:Risk Factors; D012725:Sexual Behavior; D014481:United States / Q000453:epidemiology
chemical_list: D003069:Coffee; D052638:Particulate Matter; D003042:Cocaine