1. Institute for Health Research, Kaiser Permanente Colorado, Aurora, Colorado
2. Section of Pulmonary and Critical Care, Department of Medicine, Rocky Mountain Regional Veterans Affairs Medical Center, Aurora, Colorado
3. Department of Medicine and
4. Colorado School of Public Health, Anschutz Medical Campus, University of Colorado, Aurora, Colorado
5. Department of Medicine and Academic Affairs, National Jewish Health, Denver, Colorado; and
6. Respiratory Institute, Cleveland Clinic, Cleveland, Ohio