1. Department of Surgery Keio University School of Medicine Tokyo Japan
2. Department of Healthcare Quality Assessment, Graduate School of Medicine The University of Tokyo Tokyo Japan
3. Department of Pediatric Surgery and Transplantation Kumamoto University Graduate School of Medical Sciences Kumamoto Japan
4. Department of Surgery Kochi Medical School Kochi Japan
5. Department of Gastroenterological Surgery I Hokkaido University Hospital Hokkaido Japan
6. Database Committee, The Japanese Society of Gastroenterological Surgery Tokyo Japan
7. Department of Gastrointestinal Surgery, Graduate School of Medicine The University of Tokyo Tokyo Japan
8. Tokai University Tokyo Japan
9. The Japanese Society of Gastroenterological Surgery Tokyo Japan