1. Department of Internal Medicine, Dankook University Hospital, Dankook University College of Medicine, Cheonan, Korea
2. Department of Internal Medicine, Chungnam National University College of Medicine, Cheongju, Korea
3. Department of Internal Medicine, Daejeon Eulji Medical Center, Eulji University School of Medicine, Cheongju, Korea
4. Department of Internal Medicine, Chungbuk National University School of Medicine, Cheongju, Korea
5. Department of Internal Medicine, Konyang University College of Medicine, Daejeon, Korea
6. Division of Gastroenterology, Department of Internal Medicine, College of Medicine, The Catholic University of Korea, Seoul, Korea
7. Department of Internal Medicine, Soonchunhyang University Cheonan Hospital, Cheonan, Korea