Affiliation: | 1. Department of Internal Medicine, The Catholic University of Korea, Eunpyeong St. Mary's Hospital, Seoul, South Korea;2. Department of Internal Medicine, Ulsan University Hospital, University of Ulsan College of Medicine, Ulsan, South Korea;3. Division of Gastroenterology, Department of Internal Medicine, University of Ulsan College of Medicine, Asan Medical Center, Seoul, South Korea |