Impacts of coexisting bronchial asthma on severe exacerbations in mild-to-moderate COPD: results from a national database

BACKGROUND: Acute exacerbations are major drivers of COPD deterioration. However, limited data are available for the prevalence of severe exacerbations and impact of asthma on severe exacerbations, especially in patients with mild-to-moderate COPD. METHODS: Patients with mild-to-moderate COPD (≥40 years) were extracted from Korean National Health and Nutrition Examination Survey data (2007–2012) and were linked to the national health insurance reimbursement database to obtain medical service utilization records. RESULTS: Of the 2,397 patients with mild-to-moderate COPD, 111 (4.6%) had severe exacerbations over the 6 years (0.012/person-year). Severe exacerbations were more frequent in the COPD patients with concomitant self-reported physician-diagnosed asthma compared with only COPD patients (P<0.001). A multiple logistic regression presented that asthma was an independent risk factor of severe exacerbations in patients with mild-to-moderate COPD regardless of adjustment for all possible confounding factors (adjusted odds ratio, 1.67; 95% confidence interval, 1.002–2.77, P=0.049). In addition, age, female, poor lung function, use of inhalers, and low EuroQoL five dimensions questionnaire index values were independently associated with severe exacerbation in patients with mild-to-moderate COPD. CONCLUSION: In this population-based study, the prevalence of severe exacerbations in patients with mild-to-moderate COPD was relatively low, compared with previous clinical interventional studies. Coexisting asthma significantly impacted the frequency of severe exacerbations in patients with mild-to-moderate COPD, suggesting application of an exacerbation preventive strategy in these patients.