Long-term adherence to inhaled corticosteroids and asthma control in adult-onset asthma

Background: In short-term studies poor adherence to inhaled corticosteroids (ICS) has been associated with worse asthma control but the association of long-term adherence and disease control remains unstudied. Aims and Objectives: To assess the relation between 12-year adherence to ICS and asthma control in patients with adult-onset asthma. Methods: As part of Seinäjoki Adult Asthma Study (SAAS), 181 patients with clinically confirmed new-onset adult asthma and regular ICS medication were followed for 12 years. Adherence (%) to ICS was assessed individually ((ug dispensed/ug prescribed) x 100) during the whole follow-up. Asthma control was evaluated after 12-years of treatment per GINA 2010 guideline. Results: Of the patients 31% were controlled and 69% not-controlled (partly or uncontrolled). Patients with not-controlled asthma were more often males, older, non-atopic, less educated and were prescribed higher doses of ICS than patients with controlled disease. The mean 12-year adherence to ICS was 63% (SD 38%) in patients with controlled asthma and 76% (SD 40%) in patients with not-controlled disease (p=0.042). Among patients with not-controlled asthma, those with lower 12-year adherence (<80%) had more rapid decline in FEV1 compared to patients with better adherence (>80%) (p=0.024). However, this relation was not seen in patients with controlled asthma. Conclusions: In adult-onset asthma mean 12-year adherence to ICS treatment was better in patients with not-controlled than controlled asthma. In patients with not-controlled disease, adherence <80% was associated with more rapid lung function decline underlining the importance to recognize these patients in the clinic. (NCT02733016 at ClinicalTrials.gov).