1. Department of Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
2. Department of Medicine, Chung-Ang University Gwangmyeong Hospital, Gwangmyeong, Korea
3. Division of Gastroenterology, Department of Internal Medicine, Hallym University Dongtan Sacred Heart Hospital, Hwaseong, Korea
4. Department of Internal Medicine, Chosun University College of Medicine, Gwangju, Korea
5. Department of Medicine, Samsung Changwon Hospital, Sungkyunkwan University School of Medicine, Changwon, Korea
6. Department of Medicine, Nowon Eulji Medical Center, Eulji University School of Medicine, Seoul, Korea
7. Department of Internal Medicine, College of Medicine, Kyung Hee University, Seoul, Korea
8. Division of Gastroenterology, Department of Internal Medicine, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, Korea