1. Department of Surgery Kyoto University Graduate School of Medicine Kyoto Japan
2. Department of Health Informatics Kyoto University School of Medicine and Public Health Kyoto Japan
3. Department of Healthcare Quality Assessment Tokyo University Graduate School of Medicine Tokyo Japan
4. Department of Surgery Kobe University Graduate School of Medicine Kobe Japan
5. Department of Surgery Iwate Medical University School of Medicine Iwate Japan
6. The Japanese Society of Gastroenterological Surgery Tokyo Japan
7. Database Committee The Japanese Society of Gastroenterological Surgery Tokyo Japan