Persistence, adherence, and effectiveness of combination therapy among adult patients with asthma

J Allergy Clin Immunol. 2006 Sep;118(3):574-81. doi: 10.1016/j.jaci.2006.06.034.


Background: Limited evidence exists on adherence and effectiveness of combination therapy (inhaled corticosteroids and long-acting beta(2)-agonists in the same inhaler) in asthma.

Objective: To compare persistence, adherence, and effectiveness between patients with asthma 16 to 44 years old starting combination or concurrent therapies (inhaled corticosteroids and long-acting beta(2)-agonists in 2 different inhalers).

Methods: This retrospective 1-to-1 matched cohort included newly treated asthmatics with either a combination or concurrent therapy selected from the Régie de l'assurance maladie du Québec database between 1999 and 2002. Persistence was determined by Kaplan-Meier and Cox regression analyses. Adherence was estimated by the number of prescriptions filled during the first year and compared between the 2 drug regimens using a linear regression model. Treatment effectiveness to reduce the rate of moderate to severe asthma exacerbations was estimated with Poisson regression models.

Results: Persistence fell to 10% and 5% after 12 months for combination and concurrent users, respectively. Combination users were found to be 17% less likely to stop their treatment (adjusted hazard ratio, 0.83; 95% CI, 0.78, 0.88) and filled on average 0.9 more prescription per year than concurrent users (P = .0001). Combination users were also found to be 17% less likely to have a moderate to severe asthma exacerbation (adjusted rate ratio, 0.83; 95% CI, 0.75, 0.91).

Conclusion: The observed differences in treatment persistence and adherence were found to be associated with a reduction in the rate of moderate to severe asthma exacerbations among combination users.

Clinical implications: Combination therapy might be preferred to concurrent therapy for patients with asthma with low adherence to controller therapies.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Administration, Inhalation
  • Adolescent
  • Adrenal Cortex Hormones / administration & dosage
  • Adrenergic beta-Agonists / administration & dosage
  • Adult
  • Asthma / diagnosis
  • Asthma / drug therapy*
  • Cohort Studies
  • Drug Therapy, Combination*
  • Female
  • Humans
  • Male
  • Patient Compliance*
  • Recurrence
  • Retrospective Studies
  • Treatment Outcome


  • Adrenal Cortex Hormones
  • Adrenergic beta-Agonists