Ambulatory Use of Inhaled β2-Agonists for the Treatment of Asthma in Quebec: A Population-Based Utilization Review

Study objectives: To assess whether the utilization of inhaled short-acting β 2 -agonists (ISAB) and inhaled long-acting β 2 -agonists (ILAB) for the treatment of asthma was appropriate according to the 1996 Canadian Asthma Consensus Conference recommendations. Design: Population-based retrospective drug utilization review using pharmacists' billing data of the Prescription Drug Insurance Plan administered by the Quebec health insurance board. However, the database used did not contain complete patient clinical information to accurately assess severity of asthma. Setting: Province of Quebec, Canada. Patients: Persons who received at least one outpatient prescription of ISAB (age range, 5 to 45 years) or ILAB (age range, 12 to 45 years) for the treatment of asthma between August 1997 and April 1998. Measurements: Percentages of patients whose use was appropriate according to three criteria regarding the average daily dose of ISAB (criterion 1), the renewal interval of ILAB (criterion 2), and the concomitant daily use of corticosteroids for the expected length of utilization of ILAB (criterion 3). Results: Overall proportions of appropriate use according to criterion 1 were as follows: 75% (without inhaled corticosteroids [ICS]) and 84% and 43% (with one or more than one prescription of ICS, respectively). Appropriateness was slightly higher for female patients, younger patients (5 to 18 years old), and those treated by pediatricians. However, appropriateness was only 9% among patients who received at least two prescriptions of ISAB during the study period. The proportion of appropriate use was 19% according to criterion 2 and 15% according to criterion 3; there were few differences by gender or by age, but the appropriateness according to criterion 2 was somewhat higher for patients of respirologists. Conclusion: Compared to the 1996 Canadian asthma consensus conference recommendations, ISAB are overused, ICS are underused, and ILAB are often used improperly. Close collaboration between health professionals and patients is essential to improve the pharmacotherapy of asthma.