1. Faculty of Medicine, Department of Clinical Sciences Lund, Respiratory Medicine and Allergology, Lund University, Lund, Sweden;
2. Department of Public Health and Clinical Medicine, Section for Sustainable Health, the Obstructive Lung Disease in Northern Sweden Unit, Umeå University, Umeå, Sweden;
3. Department of Medicine, University of Kentucky College of Medicine, Lexington, Kentucky; and
4. COPD Foundation, Washington, District of Columbia