1. Division of Pulmonology and Critical Care Medicine, Department of Internal Medicine, Gachon University Gil Hospital, Incheon, Korea.
2. Division of Pulmonology and Critical Care Medicine, Department of Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
3. Division of Pulmonology and Critical Care Medicine, Department of Internal Medicine, Seoul National University College of Medicine and Lung Institute, Seoul National University Hospital, Seoul and Seongnam, Korea.
4. Department of Internal Medicine, Chonnam National University Medical School, Gwangju, Korea.
5. Division of Pulmonology and Critical Care Medicine, Department of Internal Medicine, Inha University Hospital, Inha University School of Medicine, Incheon, Korea.
6. Department of Internal Medicine, Soon Chun Hyang University College of Medicine, Bucheon and Seoul, Korea.
7. Department of Internal Medicine, Chonbuk National University Medical School, Jeonju, Korea.
8. Department of Internal Medicine, The Catholic University of Korea College of Medicine, Seoul, Korea.
9. Department of Internal Medicine, Keimyung University School of Medicine, Daegu, Korea.
10. Department of Internal Medicine, Hallym University College of Medicine, Kangdong Sacred Heart Hospital, Seoul, Korea.
11. Department of Pulmonary and Critical Care Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
12. Department of Internal Medicine, Ulsan University Hospital, University of Ulsan College of Medicine, Ulsan, Korea.
13. Department of Internal Medicine, Ewha Women's University School of Medicine, Seoul, Korea.
14. Department of Internal Medicine, Younsei University College of Medicine, Seoul, Korea.