1. Division of Pulmonary and Critical Care Medicine, Department of Medicine, Mayo Clinic, Rochester, Minnesota, USA
2. Center for Clinical Epidemiology and Biostatistics and the Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
3. Division of Gastroenterology, Department of Medicine, Penn State Milton S. Hershey Medical Center, Hershey, Pennsylvania, USA
4. Department of Cardiovascular Diseases, Mayo Clinic, Rochester, Minnesota, USA
5. Department of Medicine, University of Arizona, Phoenix, Arizona, USA