1. Department of Gastroenterology and Hepatology, Faculty of Medicine and Graduate School of Medicine, Hokkaido University, Sapporo, Japan
2. Center for Gastroenterology, Teine Keijinkai Hospital, Sapporo, Japan
3. Department of Gastroenterology, Tomakomai City Hospital, Tomakomai, Japan
4. Department of Medical Oncology and Hematology, Sapporo Medical University, Sapporo, Japan
5. Department of Gastroenterology, Japanese Red Cross Kitami Hospital, Kitami, Japan
6. Department of Gastroenterology, NTT East Sapporo Hospital, Sapporo, Japan
7. Department of Gastroenterology, Kushiro Rosai Hospital, Kushiro, Japan
8. Department of Gastroenterology, Obihiro Kosei Hospital, Obihiro, Japan
9. Department of Gastroenterology, Keiwakai Ebetsu Hospital, Ebetsu, Japan
10. Department of Gastroenterology and Hepatology, Hakodate City Hospital, Hakodate, Japan
11. Department of Gastroenterology, Abashiri Kosei Hospital, Abashiri, Japan
12. Department of Gastroenterology, Oji General Hospital, Tomakomai, Japan
13. Department of Gastroenterology, National Hospital Organization Hokkaido Medical Center, Sapporo, Japan