Effect of inhaled corticosteroids on exacerbation of asthma–COPD overlap according to different diagnostic criteria

Abstract Background Few reports have investigated the efficacy of using inhaled corticosteroid (ICS)-containing inhalers to treat patients with asthma–chronic obstructive pulmonary disease (COPD) overlap (ACO). Objective To investigate the effect of ICS treatment on patients with ACO using five sets of diagnostic criteria. Methods Patients with stable COPD enrolled in the Korean COPD subgroup study (KOCOSS) cohort were assessed for asthma overlap. Patients who were prospectively followed-up for 1 year were included in an exacerbation analysis. Results Among 1,067 COPD patients, 138 (12.9%), 32 (3.0%), 171 (16%), 221 (20.7%), and 264 (24.7%) were classified as having ACO by the Global Initiative for Asthma (GINA)/Global Initiative for Chronic Obstructive Lung Disease (GOLD) criteria, the American Thoracic Society (ATS) roundtable criteria, the modified Spanish criteria, the updated Spanish criteria, and specialists’ diagnoses, respectively. According to the specialists’ diagnoses, the ACO exacerbation rate was higher than that for COPD alone (incidence rate ratio [IRR] = 1.65; p Conclusions This study suggests that ICS treatment can decrease the risk of exacerbation in patients with ACO, and that a blood eosinophil count of ≥300 cells/μL can predict the response to ICS treatment.