Background: Asthma and COPD are obstructive airway diseases related to chronic airway inflammation. However, it is known that in real practice the 2 diseases overlap.
Objective: The purpose of this study was to investigate the reality of an intermediate type between asthma and COPD, when diagnosed by physicians in Korea.
Methods: The study involved 633 Korean patients with asthma, 157 with COPD, and 41 with an intermediate type. The latter group consisted of patients with clinically mixed or overlapping characteristics of asthma and COPD. The diagnoses were dependent on physicians' clinical decisions. We analyzed the clinical differences among the 3 groups.
Results: There were differences among the 3 groups in age, sex, atopy, and body mass index. Differences in smoking status, including percentages of current smokers, duration of smoking, and number of cigarettes smoked per day, were also observed. Pre-bronchodilator FEV(1) (%), FVC (%), and FEV(1)/FVC (%) gradually decreased from the asthma group to the intermediate type group to the COPD group. Positivity of post-bronchodilator response, increase of FEV(1) (%) and post-bronchodilator FEV(1)/FVC also showed gradual patterns. For emergency department visits and hospital admissions, frequencies were lowest in the asthma group, higher in the intermediate type group, and highest in the COPD patients. All P values were statistically significant (< .001).
Conclusions: We have identified and characterized an intermediate type between asthma and COPD in clinical characteristics. Further investigations are required to determine whether these 3 conditions are part of the chronic obstructive airway diseases spectrum or are rather distinct clinical entities.