1. Department of Internal Medicine, Konkuk University School of Medicine, Seoul, Korea.
2. Department of Internal Medicine, Korea University Anam Hospital, Korea University College of Medicine, Seoul, Korea.
3. Department of Internal Medicine, Korea University Guro Hospital, Korea University College of Medicine, Seoul, Korea.
4. Department of Internal Medicine, Soon Chun Hyang University College of Medicine, Bucheon, Korea.
5. Department of Internal Medicine, Yonsei University College of Medicine, Seoul, Korea.
6. Department of Internal Medicine, Yonsei University Wonju College of Medicine, Wonju, Korea.
7. Department of Gastroenterology, Ajou University School of Medicine, Suwon, Korea.
8. Department of Internal Medicine, Hanyang University College of Medicine, Guri, Korea.
9. Department of Internal Medicine, Gachon University Gil Medical Center, Gacheon University of Medicine and Science, Incheon, Korea.