Introduction:
Chronic obstructive pulmonary disease (COPD) and asthma are chronic respiratory diseases whose incidence is still increasing. With the aging of the population, an overlap both diseases is possible (asthma-COPD overlap syndrome – ACOS). The lack of relevant data in Poland justifies the study of recognition of that problem. The aim of the study was to assess the prevalence of comorbidities of asthma and COPD and recognize the frequency of ACOS in the Silesian Voivodeship, along with the total costs of hospitalization refunded by the National Health Fund (NHF).

Material and methods:
A study was conducted on secondary epidemiological data obtained from NHF in the Silesian Voivodeship, in the period 2006–2010. We analysed the temporal variability of the standardized incidence rate of COPD and asthma in adults aged ≥ 19 years, and also we evaluated the structure of comorbidities.

Results:
The incidence of asthma and COPD remains at a high level, 392.3 (2008)–469.6 (2007)/100 000 and 470.7 (2010)–656.9 (2007)/100 000 of the adult population respectively. Cardiovascular diseases, chronic and infectious respiratory diseases as well as metabolic diseases are major comorbidities. The coexistence of asthma and COPD is more frequent in older people and concerns 5% of patients. The average unit costs of hospital treatment for asthma and COPD were 588.22 EUR and 467.38 EUR respectively.

Conclusions:
The number of first-time COPD hospitalizations is twice higher than asthma. Hospitalization is associated with the necessity to treat comorbidities, most often cardiovascular diseases. The ACOS concerns 5% of patients. Although the unit cost of treating a patient with asthma is higher than in the case of COPD, the lower number of hospitalized persons leads to a two-fold lower annual cost of treating the disease in relation to COPD.