Asthma-COPD overlap syndrome (ACOS) among subjects with newly diagnosed adult-onset asthma

Background: Recently, there has been an increasing interest in the existence of a disease entity that has characteristics of both asthma and COPD. The term that has been used for such disease entity is asthma COPD overlap syndrome, i.e. ACOS. However, there is limited knowledge on potential determinants of ACOS. Objectives: We utilized data from a population-based study on incident asthma in Southwest Finland to identify the determinants for ACOS among adult asthma patients. Methods: The study population consisted of 521 subjects 21 – 63 years of age with newly-diagnosed asthma. The study included data from an extensive questionnaire, standardized clinical examination, and spirometry. In Poisson regression models, we assessed the determinants for ACOS, while adjusting for potential confounding using prevalence ratio (PR) as the measure of association. Results: The prevalence of ACOS was 6.6% in our study population. ACOS cases had less often allergic diseases, any positive allergy skin prick tests or positive findings in Phadiatop analysis. Familial asthma was in general related to an increased risk of ACOS, while parental allergy seemed to have a protective effect against ACOS. The main determinants that were identified for ACOS were age over 50 years (adjusted PR 3.22, 95% CI 1.39-7.47), male gender (2.63, 1.14-6.07), low level education (1.36, 0.56-3.30), and current smoking (7.91, 2.25-27.81). Conclusions: The present results provide new insight into the role of allergy and heredity for ACOS among subjects with adult-onset asthma. Prevention of smoking and facilitating stopping smoking are important among asthmatic subjects to prevent development of the COPD component.