1. Department of Surgery, Seoul National University Hospital, Seoul, Korea.
2. Department of Surgery, Seoul National University Bundang Hospital, Seongnam, Korea.
3. College of Pharmacy and Research Institute of Pharmaceutical Sciences, Kyungpook National University, Daegu, Korea.
4. National Evidence-based Healthcare Collaborating Agency, Seoul, Korea.
5. Department of Surgery, Nowon Eulji Medical Center, Eulji University, Seoul, Korea.
6. Department of Surgery, Hanyang University College of Medicine, Seoul, Korea.
7. Department of Surgery, Soonchunhyang University Hospital, Seoul, Korea.
8. Department of Surgery, H+ Yangji Hospital, Seoul, Korea.
9. Department of Surgery, Keimyung University Dongsan Hospital, Daegu, Korea.
10. Department of Surgery, CHA Gangnam Medical Center, Seoul, Korea.
11. Department of Surgery, Cheil General Hospital, Seoul, Korea.
12. Department of Surgery, Asan Medical Center, Seoul, Korea.
13. Department of Surgery, Korea University Anam Hospital, Korea University College of Medicine, Seoul, Korea.
14. Department of Surgery, Ajou University Hospital, Suwon, Korea.
15. Department of Family Medicine, Kangbook Samsung Hospital, Seoul, Korea.
16. Department of Surgery, Inha University Hospital, Incheon, Korea.