1. Department of Gastroenterology, Ajou University School of Medicine, Suwon, Korea.
2. Department of Internal Medicine, The Catholic University of Korea College of Medicine, Seoul, Korea.
3. Department of Internal Medicine, Yonsei University College of Medicine, Seoul, Korea.
4. Department of Internal Medicine, Dong-A University College of Medicine, Busan, Korea.
5. Department of Internal Medicine, Korea University College of Medicine, Seoul, Korea.
6. Department of Internal Medicine, Dongguk University College of Medicine, Gyeongju, Korea.