Real-world effects of once vs greater daily inhaled corticosteroid dosing on medication adherence

Background: Nonadherence to inhaled corticosteroids (ICSs) for asthma maintenance therapy is common and is associated with poor asthma outcomes. Simplifying dosing regimens for some chronic disease conditions has resulted in better adherence; however, little is known regarding the effect of ICS dosing on adherence for the treatment of asthma. Objective: To determine whether once daily dosing is associated with higher adherence to ICS therapy when compared with 2 or more times daily dosing among patients with asthma. Methods: Six years of pharmacy claims data were linked with prescription information to estimate ICS therapy adherence for patients with asthma 12 to 56 years of age who were members of a large health maintenance organization. Patient follow-up continued from the initial ICS fill until one of the following: the last ICS fill in the observation period, a switch of ICS dosing regimen, or the initiation of ICS and long-acting beta-agonist combination therapy. Adherence was estimated by calculating a continuous multiple-interval measure of medication availability. Regression models were used to assess the relationship between adherence in patients treated with once daily vs 2 or more times daily ICS therapy. Results: Among the 1,302 patients who met the inclusion criteria, 17% were prescribed once daily therapy, and 83% were prescribed 2 or more times daily therapy. Models comparing ICS adherence among individuals following once daily and 2 or more times daily ICS regimens suggested that once daily dosing was associated with an approximately 20% increase in adherence. This significant difference persisted among subgroups defined by sex, race/ethnicity, age, and asthma severity. Conclusion: Once daily dosing was associated with higher adherence to ICS therapy; this included clinically relevant subgroups. (C) 2013 American College of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.