1 Division of Pulmonary, Allergy, and Critical Care Medicine, University of Alabama at Birmingham, Birmingham, AL 35294, USA. Electronic address: sbhatt@uabmc.edu.
2 Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, Torrance, CA, USA.
3 University of Barcelona, Respiratory Institute, Clinic Barcelona, IDIBAPS, CIBERES, Barcelona, Spain.
4 Brigham and Women's Hospital, Boston, MA, USA.
5 COPD Foundation, Miami, FL, USA.
6 Johns Hopkins University School of Medicine, Pulmonary and Critical Care Medicine, Baltimore, MD, USA.
7 Des Moines, IA, USA.
8 Division of Pulmonary, Allergy, and Critical Care Medicine, University of Alabama at Birmingham, Birmingham, AL 35294, USA.