Incidence and risk factors of chronic airway obstruction (ACOS) in a population-based asthma cohort

Abstract

Background: Subjects who have concomitant asthma and chronic airway obstruction (CAO) may be labelled with asthma-COPD overlap syndrome (ACOS), but the knowledge on risk factors and incidence of CAO among subjects with asthma is limited. Aims To investigate the incidence and risk factors of CAO in a prospective population-based adult asthma cohort study. Methods: Within the OLIN studies in northern Sweden, a large population-based asthma cohort (n=2,055, 19-72y, 55% women) was identified in clinical examinations during 1986-2001 and followed longitudinally. Several follow-ups were performed, of which the last in 2012-14 when 1,006 subjects participated. The examinations included structured interviews and spirometry. CAO was defined as post-bronchodilator FEV1/FVC Results: In the asthma cohort, 11% (n=233) fulfilled the criteria of CAO at study entry, while 17% (n=358) developed CAO during follow-ups (incident CAO). At study entry, current smoking was more common among those with incident CAO compared to asthma only, 43% vs. 26%, p Conclusions Incident CAO was common in this population-based asthma cohort. Asthmatics with incident CAO were older, more commonly smokers, but less obese at study entry compared to subjects with asthma only.