1. Department of Gastroenterology and Hepatology, Okayama University Hospital, Okayama, Japan
2. Department of Gastroenterology, Tsuyama Central Hospital, Okayama, Japan
3. Department of Gastroenterology, Iwakuni Medical Center, Hiroshima, Japan
4. Department of General Internal Medicine 2, Kawasaki Medical School, Okayama, Japan