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 [Cl]: 0.32 to 0.99) as compared with no use. Myocardial infarction decreased by 12% (95% Cl: 0% to 23%) with each additional canister used during this I-year period. The rate ratio of myocardial infarction for inhaled corticosteroid use was 0.78 (95% Cl: 0.41 to 1.51) among patients with milder asthma and 0.19 (95% Cl: 0.04 to 0.97) among those with more severe asthma. CONCLUSION: Inhaled corticosteroid use may reduce the risk of myocardial infarction in asthma patients, particularly those with more severe disease. (C) 2003 by Excerpta Medica Inc.