1. Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine
2. Department of Veterans Affairs Medical Center, Salt Lake City, Utah; and
3. Division of Public Health, Department of Family and Preventive Medicine, and
4. Division of Epidemiology, Department of Internal Medicine, University of Utah, Salt Lake City, Utah
5. Pulmonary and Critical Care Medicine, Intermountain Medical Center and LDS Hospital, Salt Lake City, Utah