1. Department of Internal Medicine, Seoul National University Hospital Healthcare System Gangnam Center, Seoul, Korea
2. Division of Gastroenterology, Department of Internal Medicine, Soonchunhyang University College of Medicine, Cheonan Hospital, Cheonan, Chungcheongnam-do, Korea
3. Institute for Digestive Research, Soonchunhyang University, Seoul, Korea
4. Department of Internal Medicine, College of Medicine, Ewha Womans University, Seoul, Korea
5. Department of Internal Medicine and Digestive Diseases Research Institute, Wonkwang University School of Medicine, Iksan, Jeollabuk-do, Korea
6. Division of Gastroenterology, Department of Internal Medicine, Kyung Hee University College of Medicine, Seoul, Korea
7. Division of Gastroenterology, Department of Internal Medicine, Chonnam National University Medical School, Gwangju, Korea
8. Division of Gastroenterology and Hepatology, Department of Internal Medicine, Keimyung University School of Medicine, Daegu, Korea
9. Department of Internal Medicine, Dankook University College of Medicine, Cheonan, Chungcheongnam-do, Korea