1. Respiratory Department, Hospital San Pedro de Alcántara, Cáceres, Spain
2. Centro de Investigación Biosanitaria en Red (CIBER) de Enfermedades Respiratorias, Madrid, Spain
3. Instituto Universitario de Investigación Biosanitaria de Extremadura, Cáceres, Spain
4. Section of Pulmonary and Critical Care, University of Chicago, Chicago, Illinois
5. Division of Pulmonary, Critical Care, and Sleep Medicine, University of California, San Diego, San Diego, California
6. American Thoracic Society, New York, New York
7. Division of Pulmonary and Critical Care, Department of Medicine, Mount Auburn Hospital, Cambridge, Massachusetts; and
8. Harvard Medical School, Boston, Massachusetts