1. Department of Respiratory Medicine, Faculty of Medicine and Health, Örebro University, Örebro, Sweden
2. Department of Medical Sciences, Respiratory; Allergy and Sleep Research, Uppsala University, Uppsala, Sweden
3. Department of Public Health and Caring Science, Family Medicine and Preventive Medicine, Uppsala University, Uppsala, Sweden
4. Division for Lung and Airway Research, Institute of Environmental Medicine, Stockholm, Sweden
5. Karolinska Severe COPD Center, Department of Respiratory Medicine, Karolinska University Hospital, Stockholm, Sweden
6. Department of Respiratory Medicine and Allergology, Lund University, Lund, Sweden
7. Department of Public Health and Clinical Medicine, Division of Medicine, Umeå University, Umeå, Sweden