1. Division of Gastroenterology, Department of Internal Medicine, Inje University Ilsan Paik Hospital, Goyang, Gyeonggi-do, Korea
2. Division of Gastroenterology, Department of Internal Medicine, Catholic Kwandong University International St. Mary’s Hospital, Incheon, Korea
3. Division of Gastroenterology, Department of Internal Medicine, Hallym University Chuncheon Sacred Heart Hospital, Chuncheon, Gangwon-do, Korea
4. Division of Gastroenterology, Department of Internal Medicine, Ulsan University Gangneung Asan Hospital, Gangneung, Gangwon-do, Korea
5. Division of Gastroenterology, Department of Internal Medicine, Eunpyeong St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Korea