1. Department of Clinical Science, Pulmonary Division, University of Bergen, Bergen, Norway
2. Department of Thoracic Medicine, Haukeland University Hospital, Bergen, Norway
3. Department of Heart Disease, Haukeland University Hospital, Bergen, Norway
4. Internal Medicine, Pulmonary Division, University of Utah, Salt Lake City, Utah, USA
5. Centre for Clinical Research, Haukeland University Hospital, Bergen, Norway