1. Department of Internal Medicine, Ewha Womans University School of Medicine, Seoul, Korea.
2. Department of Internal Medicine, Inje University Seoul Paik Hospital, Inje University College of Medicine, Seoul, Korea.
3. Department of Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
4. Department of Internal Medicine, Chung-Ang University College of Medicine, Seoul, Korea.
5. Department of Internal Medicine, Inje University Busan Paik Hospital, Inje University College of Medicine, Busan, Korea.
6. Department of Internal Medicine, Institute for Digestive Research, Digestive Disease Research Center, Soonchunhyang University College of Medicine, Seoul, Korea.
7. Department of Internal Medicine, The Catholic University of Korea College of Medicine, Seoul, Korea.