Patterns of increasing beta-agonist use and the risk of fatal or near-fatal asthma.
The association between the use of inhaled beta-agonists by metered-dose inhaler and the risk of fatal or near-fatal asthma has been demonstrated. It shows that asthmatics who use one canister of beta-agonist per month more than the number used by other similar asthmatics have twice the risk of fatal or near-fatal asthma. The present investigation assesses the magnitude of this excess risk when an asthmatic increases his/her own monthly use of inhaled beta-agonists over time. From a previous nested case-control study of 129 deaths and near-deaths from asthma (cases) and 655 controls from a cohort of 12,301 asthmatics, the subset using at least 12 inhalers during the 12 month study period was identified (97 cases and 258 controls). A profile score, ranging 0-11, was formed to quantify the patterns of beta-agonist use over time for each subject, covering the entire spectrum extending from decreasing to increasing use. The relative risk was 15.2 (95% confidence interval (CI) 2.4-96.2) per unit increase of the profile score in subjects with a pattern of increasing beta-agonist use (profile score of 6.5 or more), but this relative risk was only 1.5 (95% CI 0.8-2.6) per unit when the profile score was less than 6.5 (non-increasing use). This relative risk was independent of the risk associated with the total quantity of beta-agonist use in the 12 month period, which remained around 1.6 (95% CI 1.3-2.0) per inhaler per month.(ABSTRACT TRUNCATED AT 250 WORDS)
Suissa
S
S
Dept of Epidemiology and Biostatistics, Montreal General Hospital, McGill University, Quebec, Canada.
Blais
L
L
Ernst
P
P
D000280:Administration, Inhalation; D000318:Adrenergic beta-Agonists / Q000008:administration & dosage / Q000009:adverse effects*; D000328:Adult; D001249:Asthma / Q000188:drug therapy* / Q000401:mortality*; D016022:Case-Control Studies; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008297:Male; D009330:Nebulizers and Vaporizers; D012307:Risk Factors; D012525:Saskatchewan / Q000453:epidemiology; D012646:Self Administration / Q000639:trends; D013997:Time Factors
D000318:Adrenergic beta-Agonists