Affiliation: | 1. Department of Internal Medicine, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, , Seoul, Republic of Korea;2. Department of Gastroenterology, Asan Medical Center, University of Ulsan College of Medicine, , Seoul, Republic of Korea;3. Department of Internal Medicine, Hanyang University Guri Hospital, Hanyang University College of Medicine, , Guri, Republic of Korea |