1. Pulmonary, Allergy, and Critical Care Medicine Division, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania
2. Department of Biostatistics, Center for Clinical Epidemiology and Biostatistics, Epidemiology, and Informatics, University of Pennsylvania, Philadelphia, Pennsylvania
3. Division of Allergy, Pulmonary, and Critical Care Medicine, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee
4. Department of Cardiovascular and Metabolic Sciences, Cleveland Clinic Lerner Research Institute, Cleveland, Ohio
5. Department of Anesthesia, Cardiovascular Research Institute, and
6. Harvard School of Public Health, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts; and
7. Division of Pulmonary, Critical Care, and Sleep Medicine, University of Washington, Seattle, Washington
8. Division of Pulmonary and Critical Care Medicine, University of California, San Francisco, California