1. Division of Pulmonary, Critical Care and Sleep Medicine, Department of Medicine, National Jewish Health, Denver, Colorado
2. COPD Program, Division of Pulmonary Sciences and Critical Care Medicine, Department of Medicine, and
3. Veterans Affairs Eastern Colorado Healthcare System, Denver, Colorado
4. Division of Pulmonary Medicine, Department of Medicine, Keio University School of Medicine, Tokyo, Japan; and
5. Department of Biostatistics and Bioinformatics, University of Colorado School of Public Health, Aurora, Colorado
6. Department of Pathology, University of Colorado Anschutz Medical Campus, Aurora, Colorado