1. Division of Pulmonology, Department of Internal Medicine, Severance Hospital, Institute of Chest Diseases, Yonsei University College of Medicine, Seoul, Korea.
2. Division of Pulmonary and Critical Care Medicine, Hanyang University Guri Hospital, Hanyang University College of Medicine, Guri, Korea.
3. Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Inha University Hospital, Inha University College of Medicine, Incheon, Korea.
4. Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Ewha Womans University College of Medicine, Seoul, Korea.
5. Department of Internal Medicine, Hallym University Kangdong Sacred Heart Hospital, Lung Research Institute of Hallym University College of Medicine, Seoul, Korea.
6. Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam, Korea.
7. Division of Pulmonary and Critical Care Medicine, Kyung Hee University Hospital at Gangdong, Seoul, Korea.
8. Department of Pulmonary and Critical Care Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
9. Division of Pulmonary and Critical Care Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
10. Department of Internal Medicine, Keimyung University School of Medicine, Daegu, Korea.
11. Department of Internal Medicine, Soonchunhyang University Seoul Hospital, Seoul, Korea.
12. Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Seoul National University Hospital, Seoul, Korea.