1. Division of Gastroenterology, Department of Internal Medicine, Inha University School of Medicine, Incheon, Korea.
2. Division of Gastroenterology, Department of Internal Medicine, Soonchunhyang University Cheonan Hospital, Soonchunhyang University College of Medicine, Cheonan, Korea.
3. Department of Internal Medicine, Inje University Ilsan Paik Hospital, Inje University College of Medicine, Goyang, Korea.
4. Department of Internal Medicine, Chungbuk National University College of Medicine, Cheongju, Korea.
5. Digestive Disease Center and Research Institute, Department of Internal Medicine, Soonchunhyang University Bucheon Hospital, Soonchunhyang University College of Medicine, Bucheon, Korea.
6. Digestive Disease Center, CHA Bundang Medical Center, CHA University, Seongnam, Korea.