1. Department of Internal Medicine, Seoul National University College of Medicine, Seoul National University Bundang Hospital, Seongnam, Korea.
2. Department of Internal Medicine, Sungkyunkwan University School of Medicine, Seoul, Korea.
3. Department of Pediatrics, Sungkyunkwan University School of Medicine, Seoul, Korea.
4. Department of Internal Medicine, Chonnam National University College of Medicine, Gwangju, Korea.
5. Department of Internal Medicine, The Catholic University of Korea College of Medicine, Seoul, Korea.