1. Department of Internal Medicine, Dongsan Medical Center, Keimyung University School of Medicine, Daegu, Korea.
2. Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam, Korea.
3. Division of Pulmonology and Critical Care Medicine, Department of Internal Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
4. Department of Infectious Diseases, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.