1. Division of Gastroenterology and Hepatology, Department of Internal Medicine, Yeouido St. Mary's Hospital, College of Medicine, The Catholic University of Korea , Seoul , Republic of Korea
2. Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Incheon St. Mary's Hospital, College of Medicine, The Catholic University of Korea , Seoul , Republic of Korea
3. Division of Pulmonary, Allergy, and Critical Care Medicine, Department of Internal Medicine, Bucheon St. Mary's Hospital, College of Medicine, The Catholic University of Korea , Seoul , Republic of Korea
4. Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Chungnam National University Hospital , Daejeon , Republic of Korea
5. Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Uijeongbu St. Mary's Hospital, College of Medicine, The Catholic University of Korea , Seoul , Republic of Korea
6. Division of Pulmonary, Allergy, and Critical Care Medicine, Department of Internal Medicine, Korea University Guro Hospital, Korea University College of Medicine , Seoul , Republic of Korea
7. Division of Pulmonary, Critical Care, and Sleep Medicine, Department of Internal Medicine, Eunpyeong St. Mary's Hospital, College of Medicine, The Catholic University of Korea , Seoul , Republic of Korea
8. Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, St. Vincent's Hospital, College of Medicine, The Catholic University of Korea , Seoul , Republic of Korea
9. Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Chungbuk National University Hospital , Cheongju , Republic of Korea
10. Department of Pulmonary and Critical Care Medicine, Soonchunhyang University Cheonan Hospital, Soonchunhyang University College of Medicine , Cheonan , Republic of Korea
11. Division of Pulmonary, Allergy, and Critical Care Medicine, Department of Internal Medicine, Kangdong Sacred Heart Hospital, Hallym University College of Medicine , Seoul , Republic of Korea
12. Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Konyang University Hospital, Konyang University College of Medicine , Daejeon , Republic of Korea
13. Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Dongguk University Ilsan Hospital , Goyang , Republic of Korea
14. Division of Allergy and Respiratory Medicine, Soonchunhyang University Bucheon Hospital, Soonchunhyang University College of Medicine , Bucheon , Republic of Korea
15. Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Ilsan Paik Hospital, Inje University College of Medicine , Goyang , Republic of Korea
16. Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Ulsan University Hospital, Ulsan University College of Medicine , Ulsan , Republic of Korea
17. Division of Pulmonology, Departments of Internal Medicine, Gachon University Gil Hospital , Incheon , Republic of Korea
18. Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Yeouido St. Mary's Hospital, College of Medicine, The Catholic University of Korea , Seoul , Republic of Korea
19. 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 , Republic of Korea