1. Department of Thoracic and Occupational Medicine, Trondheim University Hospital, Trondheim, Norway
2. Department of Circulation and Medical Imaging, Norwegian University of Science and Technology, Trondheim, Norway
3. Department of Public Health and Nursing, Faculty of Medicine, Norwegian University of Science and Technology, Trondheim, Norway
4. K.G. Jebsen Center for Genetic Epidemiology, Department of Public Health and Nursing, Faculty of Medicine and Health Sciences, Norwegian University of Science and Technology, Trondheim, Norway