Background: The ratio of controller medication to total asthma medications has been related to asthma utilization outcomes, but its relationship to patient-centered outcomes has not been explored.
Methods: Surveys that included validated asthma quality-of-life, control, and symptom severity tools were completed by a random sample of 2,250 health maintenance organization members aged 18 to 56 years who had persistent asthma. Linked computerized pharmacy data provided dispensing information on β-agonist canisters and asthma controller medication. The ratio was calculated as the number of controller medications dispensed during the year of the survey divided by the total number medications (ie, inhaled β-agonist plus controller medications) dispensed. The relationships of the optimal ratio cutoff to patient-centered outcomes and to subsequent acute asthma exacerbations were determined.
Results: Mean asthma quality-of-life, asthma control, and symptom severity scale scores were significantly (p < 0.0001) more favorable in patients with ratios of ≥ 0.5. After adjusting for demographic characteristics, patients with ratios of ≥ 0.5 were significantly less likely to have adverse results regarding asthma quality of life (odds ratio [OR], 0.65; 95% confidence interval [CI], 0.52 to 0.80), asthma control (OR, 0.62; 95% CI, 0.50 to 0.77), and symptom severity (OR, 0.53; 95% CI, 0.43 to 0.65), and were also less likely to experience subsequent asthma hospitalizations or emergency department visits (OR, 0.44; 95% CI, 0.26 to 0.74) than patients with lower ratios.
Conclusion: A higher controller medication/total asthma medication ratio is associated with better patient-centered asthma outcomes as well as with reduced emergency hospital utilization. This adds further support to the use of the medication ratio as an asthma quality-of-care measure.