1. Division of Pulmonary, Allergy, and Critical Care Medicine, University of Alabama at Birmingham, Birmingham, Alabama;
2. Respiratory Research Institute, Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, Torrance, California;
3. Division of Pulmonary, Allergy, and Critical Care Medicine, Duke University School of Medicine, Durham, North Carolina;
4. Duke Clinical Research Institute, Durham, North Carolina;
5. Section of Pulmonary, Critical Care and Sleep Medicine, Yale University School of Medicine, New Haven, Connecticut;
6. Veterans Affairs Connecticut Healthcare System, West Haven, Connecticut; and
7. University of California, San Francisco, San Francisco, California