1. Department of Internal Medicine, Kyung Hee University Hospital at Gangdong, Seoul, Korea.
2. Department of Internal Medicine, Kyung Hee University School of Medicine, Seoul, Korea.
3. Department of Internal Medicine, Soonchunhyang University College of Medicine, Cheonan, Korea.
4. Department of Internal Medicine, Dankook University College of Medicine, Cheonan, Korea.
5. Department of Internal Medicine and Gastrointestinal Cancer Center, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, Korea.