1. Division of Pulmonary and Critical Care Medicine, Department of Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
2. Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Severance Hospital, Yonsei University College of Medicine, Seoul, Korea.
3. Division of Allergy, Pulmonary and Critical Care Medicine, Department of Internal Medicine, Gachon University Gil Medical Center, Incheon, Korea.
4. Division of Allergy and Respiratory Medicine, Department of Internal Medicine, Soonchunhyang University Bucheon Hospital, Bucheon, Korea.
5. Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, School of Medicine, Inha University, Incheon, Korea.
6. Division of Pulmonary, Allergy, and Critical Care Medicine, Department of Internal Medicine, Busan Paik Hospital, Inje University, Busan, Korea.
7. Division of Pulmonary, Department of Internal Medicine, College of Medicine, Wonkwang University, Iksan, Korea.
8. Division of Pulmonary and Critical Medicine, Department of Internal Medicine, Ulsan University Hospital, College of Medicine, University of Ulsan, Ulsan, Korea.
9. Department of Internal Medicine, Gyeongsang National University Hospital, Jinju, Korea.
10. Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Seoul St. Mary’s Hospital, College of Medicine, The Catholic University of Korea, Seoul, Korea.
11. Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Ilsan Paik Hospital, Inje University College of Medicine, Goyang, Korea.
12. Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, College of Medicine, Seoul National University, Seoul, Korea.
13. Division of Respiratory-Allergy and Clinical Immunology, Department of Internal Medicine, Konkuk University Medical Center, Seoul, Korea.
14. Department of Pulmonary and Critical Care Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
15. Department of Pulmonary and Critical Care Medicine, Ajou University School of Medicine, Suwon, Korea.
16. Department of Internal Medicine, Myongji Hospital, Hanyang University College of Medicine, Goyang, Korea.
17. Division of Pulmonary, Allergy and Critical Care Medicine, Department of Internal Medicine, Kyunghee University Hospital, Seoul, Korea.