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Allergy Asthma Immunol Res. 2017 Sep;9(5):431-437. doi: 10.4168/aair.2017.9.5.431.

Asthma-COPD Overlap Shows Favorable Clinical Outcomes Compared to Pure COPD in a Korean COPD Cohort.

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Department of Internal Medicine, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul, Korea.
Department of Internal Medicine, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul, Korea.
Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Ewha Womans University College of Medicine, Seoul, Korea.
Regional Center for Respiratory Disease, Yeungnam University Medicial Center, Yeungnam University College of Medicine, Daegu, Korea.
Division of Respiratory and Allergy Medicine, Soonchunhyang University Seoul Hospital, Seoul, Korea.
Department of Internal Medicine, Ulsan University Hospital, University of Ulsan College of Medicine, Ulsan, Korea.
Department of Internal Medicine, Konkuk University School of Medicine, Seoul, Korea.
Division of Pulmonary Medicine, Department of Internal Medicine, Hallym University Sacred Heart Hospital, Hallym University College of Medicine, Anyang, Korea.



Comparisons of the characteristics of chronic obstructive pulmonary disease (COPD) and asthma-COPD overlap syndrome (ACOS) have been the focus of several studies since the diseases were defined by the Global Initiative for Asthma and Global Initiative for Chronic Obstructive Lung Disease guidelines. However, no consensus is available yet. In this study, we aimed to compare the characteristics of asthma-COPD overlap (ACO) and COPD.


We retrospectively reviewed 1,504 patients with COPD in a Korean COPD Subtype Study cohort. The occurrence of ACO was defined as a positive response to a bronchodilator (an increase in forced expiratory volume in 1 second [FEV1] of 12% and 200 mL).


Among 1,504 patients with COPD, 223 (14.8%) were diagnosed with ACO. Men (95.5%) and current smokers (32.9%) were more prevalent in the ACO group compared with the pure COPD group (90.5% and 25.3%, respectively; P=0.015 and P=0.026, respectively). Patients with ACO had a better quality of life (St. George's Respiratory Questionnaire for COPD score=31.0±18.0 [mean±standard deviation]) than those with pure COPD (35.3±19.1) (P=0.002). Although the prevalence of acute exacerbation was not different between the 2 groups, patients with severe exacerbation required hospital admission significantly more frequently in the pure COPD group than in the ACO group. Patients with ACO showed a higher likelihood of FEV1 recovery than those with pure COPD (P<0.001).


We suggest that ACO is characterized by less severe symptoms, and therefore it might lead to rare severe exacerbation and the possibility of lung function recovery.


Chronic obstructive pulmonary disease; asthma-chronic obstructive pulmonary disease overlap syndrome; disease progression

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