1. Department of Medicine, Samsung Medical Center, Sungkyunkwan Univsersity School of Medicine, Seoul, Korea.
2. Department of Medicine, The Catholic University of Korea, Seoul, Korea.
3. Department of Medicine, Kyungpook National University School of Medicine, Daegu, Korea.
4. Department of Medicine, Yonsei University College of Medicine, Seoul, Korea.
5. Department of Medicine, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam, Korea.
6. Institute for Digestive Research, Soonchunhyang University College of Medicine, Seoul, Korea.
7. Department of Medicine, Department of Internal Medicine, Korea University College of Medicine, Seoul, Korea.