Heterogeneity of asthma and COPD overlap

Abstract

Background

Asthma and COPD are heterogeneous diseases. Patients with both disease features (asthma–COPD overlap [ACO]) are common. However, clinical characteristics and socio-economic burden of ACO are still controversial. The aim of this study was to identify the heterogeneity of ACO and to find out the subtypes with clinical impact among ACO subtypes.

Methods

In the Korean National Health and Nutrition Examination Survey (KNHANES) conducted between 2007 and 2012, subjects who were ≥40 years and had prebronchodilator FEV₁/FVC <0.7 and FEV₁ ≥50% predicted were included. The presence or absence of self-reported wheezing was indicated by W+ or W− and used as an index of airway hyper-responsiveness. S+/S− was defined as subjects who were smokers/never smokers. The subjects were divided into the following four groups: W−S−, W−S+, W+S−, and W+S+. W+S− and W+S+ were asthma-predominant ACO and COPD-predominant ACO, respectively. KNHANES and linked National Health Insurance data were analyzed.

Results

The asthma-predominant ACO group showed the lowest socioeconomic status, FEV₁, FVC% predicted, and quality of life (QoL) levels. The COPD-predominant ACO group showed the highest hospitalization rate, outpatient medical cost, and total and outpatient health care utilization. COPD-predominant ACO was associated with exacerbations compared to the W−S− group (adjusted odds ratio [aOR], 1.79; 95% confidence interval [CI], 1.12–2.85; P=0.015) and W−S+ group (OR 2.11; 95% CI 1.43–3.10; P<0.001). COPD-predominant ACO was associated with increased medical cost.

Conclusion

Asthma-predominant ACO individuals displayed poorer socioeconomic status and QoL compared to the COPD-predominant ACO group. The COPD-predominant ACO group displayed more frequent exacerbations and greater medical costs. Considering the heterogeneity of ACO, it is desirable to identify subtypes of ACO patients and appropriately allocate limited medical resources.

Keywords:

• asthma
• COPD
• overlap
• heterogeneity
• health care utilization
• exacerbation

Acknowledgments

This research was supported by the intramural research promotion grants from Ewha Womans University School of Medicine, Korea Centers for Disease Control and Prevention (2014-E33003-00), and National Research Foundation of Korea Grant funded by the Korean Government (2010-0027945). HIRA provided the NHI claim database and merged them with data from the Korean National Health and Nutritional Examination Survey (KNHANES).

Disclosure

CK Rhee received consulting/lecture fees from MSD, AstraZeneca, Novartis, GSK, Takeda, Mundipharma, Sandoz, Boehringer-Ingelheim, and Teva-Handok. The other authors report no conflicts of interest in this work.