1. Department of Internal Medicine, St. Vincent's Hospital, College of Medicine, The Catholic University of Korea, Suwon, Korea.
2. Department of Internal Medicine, Seoul Paik Hospital, Inje University College of Medicine, Seoul, Korea.
3. Department of Internal Medicine, Digestive Disease Research Institute, Wonkwang University College of Medicine, Iksan, Korea.
4. Department of Internal Medicine, Haeundae Paik Hospital, Inje University College of Medicine, Busan, Korea.
5. Department of Gastroenterology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.