Inhaled corticosteroid use in asthma and the prevention of myocardial infarction.
BACKGROUND
Asthma patients may be at increased risk of cardiovascular outcomes due to hypoxemia from asthma exacerbations and bronchodilator-induced tachycardia. We investigated whether inhaled corticosteroids, which are known to improve asthma control and reduce exacerbations, are associated with a lower rate of myocardial infarction.


METHODS
We used the Saskatchewan Health databases to form a population-based cohort of subjects aged 5 to 44 years who were using antiasthma drugs between 1975 and 1991. Subjects were followed until 1997, the age of 55 years, or death. A nested case-control approach was used where each subject with a first myocardial infarction was matched on calendar time, age, and sex with up to 10 controls randomly selected from the cohort.


RESULTS
The cohort consisted of 30,569 subjects, including 105 patients with myocardial infarction who were matched with 933 controls. The adjusted rate ratio of myocardial infarction for inhaled corticosteroid use during the year before the index date was 0.56 (95% confidence interval [CI]: 0.32 to 0.99) as compared with no use. Myocardial infarction decreased by 12% (95% CI: 0% to 23%) with each additional canister used during this 1-year period. The rate ratio of myocardial infarction for inhaled corticosteroid use was 0.78 (95% CI: 0.41 to 1.51) among patients with milder asthma and 0.19 (95% CI: 0.04 to 0.97) among those with more severe asthma.


CONCLUSIONS
Inhaled corticosteroid use may reduce the risk of myocardial infarction in asthma patients, particularly those with more severe disease.
Suissa
Samy
S
Division of Clinical Epidemiology, Royal Victoria Hospital, and Epidemiology and Biostatistics and Medicine, McGill University, Montreal, Québec, Canada. samy.suissa@clinepi.mcgill.ca
Assimes
Themistocles
T
Brassard
Paul
P
Ernst
Pierre
P
D000280:Administration, Inhalation; D018927:Anti-Asthmatic Agents / Q000008:administration & dosage / Q000627:therapeutic use*; D000893:Anti-Inflammatory Agents / Q000008:administration & dosage / Q000627:therapeutic use*; D001249:Asthma / Q000188:drug therapy* / Q000453:epidemiology; D001993:Bronchodilator Agents / Q000627:therapeutic use; D016022:Case-Control Studies; D015331:Cohort Studies; D015986:Confounding Factors, Epidemiologic; D016208:Databases, Factual / Q000706:statistics & numerical data; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000453:epidemiology / Q000517:prevention & control*; D012307:Risk Factors; D012525:Saskatchewan / Q000453:epidemiology; D013256:Steroids; D013997:Time Factors
D018927:Anti-Asthmatic Agents; D000893:Anti-Inflammatory Agents; D001993:Bronchodilator Agents; D013256:Steroids