1. Department of Internal Medicine, Keimyung University School of Medicine, Daegu, Korea
2. Division of Gastroenterology, Department of Internal Medicine, Eunpyeong St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Korea
3. Department of Gastroenterology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea
4. Department of Gastroenterology, Internal Medicine, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul, Korea
5. Department of Gastroenterology, Internal Medicine, Severance Hospital, Yonsei University College of Medicine, Seoul, Korea
6. Department of Internal Medicine, Chungnam National University School of Medicine, Daejeon, Korea
7. Digestive Disease Center and Research Institute, Department of Internal Medicine, Soonchunhyang University College of Medicine, Bucheon, Gyeonggi-do, Korea