Socioeconomic impact of asthma, chronic obstructive pulmonary disease and asthma-COPD overlap syndrome

Background: Asthma-chronic obstructive pulmonary disease (COPD) overlap syndrome (ACOS) is defined as having both features of asthma and COPD, which are airway hyper-responsiveness and incompletely reversible airway obstruction. However, socioeconomic impact of ACOS have not been well appreciated. Methods: Adults with available wheezing history and acceptable spirometry were selected from the fourth Korean National Health and Nutrition Examination Survey (KNHANES IV) in 2007-2009. Their data were merged with the Korean National Health Insurance claim data. 'Asthma group' was defined as having self-reported wheezing history and FEV1/FVC >= 0.7, 'COPD group' was defined as having FEV1/FVC <0.7 and no wheezing, 'ACOS group' was defined as having both wheezing and FEV1/FVC <0.7, and 'no airway disease (NAD) group' was defined as having no wheezing and FEV1/FVC >= 0.7. Results: Among a total of 11,656 subjects, ACOS comprise 2.2%; COPD, 8.4%; asthma, 5.8% and NAD, 83.6%. Total length of healthcare utilization and medical costs of ACOS group was the top among four groups (P<0.001), though inpatient medical cost was the highest in COPD group (P=0.025). Multiple linear regression analyses showed that ACOS group (beta=12.63, P<0.001) and asthma group (beta=6.14, P<0.001) were significantly associated with longer duration of healthcare utilization and ACOS group (beta=350,475.88, P=0.008) and asthma group (beta=386,876.81, P<0.001) were associated with higher medical costs. Conclusions: This study demonstrated that ACOS independently influences healthcare utilization after adjusting several factors. In order to utilize limited medical resources efficiently, it may be necessary to find and manage ACOS patients.