1. Department of Internal Medicine, Kyung Hee University Medical Center, Seoul, Korea.
2. Division of Pulmonary, Allergy and Critical Care Medicine, Department of Internal Medicine, Hallym University Kangdong Sacred Heart Hospital, Seoul, Korea.
3. Lung Research Institute, Hallym University College of Medicine, Chuncheon, Korea.
4. Division of Pulmonology, Critical Care and Sleep Medicine, Department of Internal Medicine, College of Medicine, The Catholic University of Korea, Seoul, Korea.
5. Division of Pulmonary and Critical Care Medicine, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, Korea.
6. Division of Pulmonology, Department of Internal Medicine, Hanyang University Guri Hospital, Hanyang University College of Medicine, Guri, Korea.
7. Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Ajou University School of Medicine, Suwon, Korea.
8. Division of Pulmonary, Allergy, and Critical Care Medicine, Department of Internal Medicine, Yonsei University Wonju College of Medicine, Wonju, Korea.
9. Division of Pulmonary, Allergy and Critical Care Medicine, Chonbuk National University Hospital, Chonbuk National University Medical School, Jeonju, Korea.
10. Division of Pulmonology and Critical Care Medicine, Department of Internal Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
11. Department of Internal Medicine, Kangwon National University School of Medicine, Chuncheon, Korea.
12. Department of Internal Medicine, Pusan National University School of Medicine, Yangsan, Korea.
13. Regional Center for Respiratory Disease, Yeungnam University Medical Center, Yeungnam University College of Medicine, Daegu, Korea.
14. Division of Allergy and Respiratory Medicine, Department of Internal Medicine, Soonchunhyang University Bucheon Hospital, Bucheon, Korea.
15. Department of Clinical Pharmacology, Konkuk University School of Medicine, Seoul, Korea.
16. Department of Internal Medicine, Konkuk University Medical Center, Seoul, Korea.
17. Division of Pulmonary, Allergy and Critical Care Medicine, Department of Internal Medicine, Korea University Guro Hospital, Seoul, Korea.
18. Division of Pulmonary, Allergy and Critical Care Medicine, Department of Internal Medicine, Hallym University Sacred Heart Hospital, Anyang, Korea.