1. Department of Respiratory Medicine, Hvidovre University Hospital, DK-2650 Hvidovre, Denmark and Institute of Clinical Medicine, University of Copenhagen, Copenhagen, Denmark
2. Section of Epidemiology, Department of Public Health, Medical Department, Herlev-Gentofte Hospital, University of Copenhagen, DK-1014 Copenhagen K, Denmark, Herlev, Denmark
3. Department of Medicine, Vejle Hospital, Southern Denmark University Hospital, Denmark