1. Division of Gastroenterology, National Medical Center, Seoul, Korea.
2. Department of Medicine, The Graduate School, Yonsei University, Seoul, Korea.
3. Department of Internal Medicine, Dongguk University Ilsan Hospital, Dongguk University College of Medicine, Goyang, Korea.
4. Department of Internal Medicine, Chosun University College of Medicine, Gwangju, Korea.
5. Department of Internal Medicine, Konyang University College of Medicine, Daejeon, Korea.
6. Department of Internal Medicine, Chungbuk National University College of Medicine, Cheongju, Korea.
7. Department of Internal Medicine, Soonchunhyang University College of Medicine, Seoul, Korea.
8. Department of Gastroenterology, Myongji Hospital, Goyang, Korea.
9. Department of Gastroenterology, Wonkwang University Hospital, Iksan, Korea.