1. Department of Internal Medicine, Kyung Hee University Hospital at Gangdong, Kyung Hee University School of Medicine, Seoul, Korea
2. Department of Internal Medicine, Chonan Hospital, Soonchunhyang University College of Medicine, Chonan, Korea
3. Department of Internal Medicine, Chonnam National University Hwasun Hospital, Chonnam National University Medical School, Hwasun, Korea
4. Department of Internal Medicine and Institute of Gastroenterology, Yonsei University Severance Hospital, Yonsei University College of Medicine, Seoul, Korea
5. Department of Internal Medicine, Soonchunhyang University Seoul Hospital, Soonchunhyang University College of Medicine, Seoul, Korea
6. Department of Internal Medicine, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, Korea
7. Department of Internal Medicine, Ewha Mokdong University Hospital, Ewha Womans University School of Medicine, Seoul, Korea
8. Department of Internal Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea
9. Department of Internal Medicine, Dankook University Hospital, Dankook University College of Medicine, Chonan, Korea