Study objectives: To assess trends in asthma management and to identify factors associated with increasing short-acting (SA) β-agonist utilization in British Columbia using administrative prescription data.
Design: A retrospective cohort analysis.
Setting: All patients between 13 and 50 years of age who had received at least one prescription for a SA β-agonist covered by BC Pharmacare between January 1, 1996, and December 31, 1998.
Methods: Cross-sectional analysis of all patients, and longitudinal analyses only of patients who had received at least one SA β-agonist prescription in each of the 3 years. Trends in asthma medication use over time were evaluated using repeated-measures Mantel-Haenszel tests. Multiple logistic regression was used to identify factors associated with increasing SA β-agonist use.
Results: A total of 78,758 patients were included in the cohort. No decrease in the annual prevalence of receiving more than four canisters per year of a SA β-agonist was identified between 1996 and 1998. A total of 12,844 patients filled at least one SA β-agonist prescription each year. Time-trend analysis showed an overall increasing probability of not receiving an inhaled corticosteroid (ICS) agent in this population (p = 0.002). In patients exhibiting low SA β-agonist use, > 18 years of age (adjusted odds ratio [OR], 1.5), male gender (adjusted OR, 1.7), and in receipt of social assistance (adjusted OR, 2.3) were associated with receiving increasing amounts of SA β-agonist agents over the 3 years. In patients with a high degree of use of SA β-agonists, only the receipt of social assistance (adjusted OR, 1.3) was significantly associated with increasing use.
Conclusions: Despite the development and dissemination of asthma management guidelines, there was no trend toward decreasing SA β-agonist use. An unexpected trend toward decreasing ICS utilization was identified. Receiving social assistance was a risk factor for increasing SA β-agonist use, independent of baseline utilization.