Background: Overlap syndrome of asthma and chronic obstructive pulmonary disease (COPD) is a common condition, which is not well understood. This study describes the characteristics and hospital impact of patients suffering from this condition.
Methods: The data are comprised of the hospital discharge registry data maintained by National Institute for Health and Welfare [Terveyden ja hyvinvoinnin laitos (THL)] between 1972 and 2009 covering the entire Finnish population (5.35 million inhabitants in 2009). In THL, treatment periods for patients with the primary or secondary diagnosis of asthma or COPD were selected. From that data, patients over 34 years and their treatment periods starting and ending 2000-2009 with a principal or secondary diagnosis of asthma [International Classification of Diseases (ICD) 10: J45-J46] or COPD (ICD 10: J41-J44) were picked up. There were 105 122 such patients who had 343 420 treatment periods altogether.
Results: Patients with asthma were younger than patients with COPD and overlap syndrome, while COPD and overlap syndrome patients' age distribution was very similar. Patients with both asthma and COPD had 30.4% of all treatment periods, even though the percentage of all patients in this group was only 16.1%. These patients had an increased number of hospitalisation episodes across all age groups. Average number of treatment periods during 2000-2009 was 2.1 in asthma, 3.4 in COPD and 6.0 in overlap syndrome. Hospital impact of the same period in asthma was 939 900 days in COPD 1 517 308 and 1 000 724 days in overlap syndrome.
Conclusion: Overlap syndrome of asthma and COPD is a common condition with high hospital impact for patients with this condition.
Keywords: COPD; asthma; exacerbation; hospital burden; overlap syndrome.
© 2013 John Wiley & Sons Ltd.