Comparison of Clinical Characteristics and Incidence of Acute Exacerbation in Patients with Asthma‐copd Overlap and Copd

Background and Aims: Asthma-COPD overlap (ACO) is characterized by persistent airflow limitation with several features usually associated with asthma and COPD. Acute exacerbation (AE) of ACO and COPD is an important event that worsens prognosis. The aim of this study was to investigate and compare clinical characteristics and incidence of AE between patients with ACO and COPD. Methods: We examined 45 ACO patients and 171 COPD patients who visited our hospital from 2014 to 2016. AE was defined as an episode requiring treatment with oral corticosteroid and/or antibiotics, or a visit to the emergency room, or hospitalization. Results: The frequency of use of inhaled corticosteroids and a longacting beta2-agonist was significantly higher in the ACO patients vs the COPD patients (86.7 vs 30.4%, P < 0.001 and 88.9 vs 67.3%, P = 0.005, respectively). Patients with ACO had lower body mass index than those with COPD (21.2 vs 21.4 kg/m, P = 0.031). There was a significant difference between the COPD and ACO patients in exposure to tobacco smoke (52.0 vs 35.4 pack-years, P = 0.011). There were no significant differences in age, gender ratio, and pulmonary function test results. During the follow-up period (median, 517 days), 26 patients with ACO and 65 patients with COPD suffered AE. Log-rank test showed that ACO patients had a higher incidence rate of AE than COPD patients (P = 0.002). Conclusion: ACO patients had different clinical characteristics and a higher incidence rate of AE than COPD patients. Clinicians need to identify the characteristics of and prescribe more appropriate treatment for ACO patients.