Asthma, COPD and overlap syndrome: a longitudinal study in young European adults

We compared risk factors and clinical characteristics, 9-year lung function change and hospitalisation risk across subjects with the asthma-chronic obstructive pulmonary disease (COPD) overlap syndrome (ACOS), asthma or COPD alone, or none of these diseases. Participants in the European Community Respiratory Health Survey in 1991-1993 (aged 20-44 years) and 1999-2001 were included. Chronic airflow obstruction was defined as pre-bronchodilator forced expiratory volume in 1 s (FEV1)/forced vital capacity