Low-dose inhaled corticosteroids and the prevention of death from asthma.

Background: Although inhaled corticosteroids are effective for the treatmen t of asthma, it is uncertain whether their use can prevent death from asthm a. Methods: We used the Saskatchewan Health data bases to form a population-ba sed cohort of all subjects from 5 through 44 years of age who were using an tiasthma drugs during the period from 1975 through 1991. We followed subjec ts until the end of 1997, their 55th birthday, death, emigration, or termin ation of health insurance coverage, whichever came first. We conducted a ne sted case-control study in which subjects who died of asthma were matched w ith controls within the cohort according to the length of follow-up at the time of death of the case patient (the index date), the date of study entry , and the severity of asthma. We calculated rate ratios after adjustment fo r the subject's age and sex; the number of prescriptions of theophylline, n ebulized and oral (beta)-adrenergic agonists, and oral corticosteroids in t he year before the index date; the number of canisters of inhaled (beta)-ad renergic agonists used in the year before the index date; and the number of hospitalizations for asthma in the two years before the index date. Results: The cohort consisted of 30,569 subjects. Of the 562 deaths, 77 wer e classified as due to asthma. We matched the 66 subjects who died of asthm a for whom there were complete data with 2681 controls. Fifty-three percent of the case patients and 46 percent of the control patients had used inhal ed corticosteroids in the previous year, most commonly low-dose beclomethas one. The mean number of canisters was 1.18 for the patients who died and 1. 57 for the controls. On the basis of a continuous dose-response analysis, w e calculated that the rate of death from asthma decreased by 21 percent wit h each additional canister of inhaled corticosteroids used in the previous year (adjusted rate ratio, 0.79; 95 percent confidence interval, 0.65 to 0. 97). The rate of death from asthma during the first three months after disc ontinuation of inhaled corticosteroids was higher than the rate among patie nts who continued to use the drugs. Conclusions: The regular use of low-dose inhaled corticosteroids is associa ted with a decreased risk of death from asthma. (N Engl J Med 2000;343:332- 6.) (C) 2000, Massachusetts Medical Society.