1. Division of Pulmonary Medicine, Department of Internal Medicine, Yonsei University, College of Medicine, Yonsei University Health System, Seoul, Korea.
2. Department of Pulmonary and Critical Care Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
3. Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine and Lung Institute, Seoul National University College of Medicine, Seoul, Korea.
4. Division of Pulmonary and Critical Care Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
5. Division of Pulmonary, Allergy and Critical Care Medicine, Department of Internal Medicine, Korea University Anam Hospital, Seoul, Korea.
6. Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Kyungpook National University Hospital, Daegu, Korea.
7. Division of Allergy and Respiratory Medicine, Department of Internal Medicine, Soonchunhyang University Hospital, Seoul, Korea.
8. Division of Allergy and Respiratory Medicine, Department of Internal Medicine, Soonchunhyang University Bucheon Hospital, Bucheon, Korea.
9. Division of Pulmonology, Department of Internal Medicine, Gachon University Gil Medical Center, Incheon, Korea.
10. Division of Pulmonary, Allergy & Critical Care Medicine, Department of Internal Medicine, Hallym University Kangdong Sacred Heart Hospital, Seoul, Korea.
11. Pulmonary Division, Department of Internal Medicine, Inha University Hospital, Incheon, Korea.