1. Department of Internal Medicine, Seoul National University Hospital, Seoul, Korea.
2. Department of Internal Medicine, Armed Forces Capital Hospital, Seongnam, Korea.
3. Department of Internal Medicine, Seoul National University Bundang Hospital, Seongnam, Korea.
4. WCU Department of Molecular Medicine and Biopharmaceutical Sciences, Medical Research Institute, Seoul National University College of Medicine, Seoul, Korea.
5. Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Korea.