1. Department of Gastroenterology and Oncology Institute of Biomedical Sciences Tokushima University Graduate School of Medicine Tokushima Tokushima Japan
2. Department of Community Medicine for Gastroenterology and Oncology Institute of Biomedical Sciences Tokushima University Graduate School of Medicine Tokushima Tokushima Japan
3. Department of Gastroenterology and Neurology Kagawa University Graduate School of Medicine Miki‐cho Kagawa Japan
4. Department of Gastroenterology and Hepatology Kochi University Graduate School of Medicine Kochi Kochi Japan
5. Department of Gastroenterology and Hepatology Takamatsu Red Cross Hospital Takamatsu Kagawa Japan