1) Department of Surgery, Graduate School of Medicine, Kyoto University, Kyoto, Japan
2) Department of Gastrointestinal Surgery, Tenri Hospital, Tenri, Japan
3) Department of Surgery, Kobe City Nishi-Kobe Medical Center, Kobe, Japan
4) Department of Surgery, Kobe City Medical Center General Hospital, Kobe, Japan
5) Department of Surgery, Osaka Red Cross Hospital, Osaka, Japan
6) Department of Surgery, Hyogo Prefectural Amagasaki General Medical Center, Amagasaki, Japan
7) Department of Surgery, National Hospital Organization Kyoto Medical Center, Kyoto, Japan
8) Department of Surgery, Shiga General Hospital, Moriyama, Japan
9) Department of Gastroenterological Surgery and Oncology, Himeji Medical Center, Himeji, Japan
10) Department of Surgery, Kobe City Medical Center West Hospital, Osaka, Japan
11) Department of Surgery, Kyoto Katsura Hospital, Kyoto, Japan
12) Department of Surgery, Kyoto City Hospital, Kyoto, Japan
13) Department of Surgery, Otsu City Hospital, Otsu, Japan
14) Department of Gastroenterological surgery, Japanese Red Cross Wakayama Medical Center, Wakayama, Japan
15) Department of Surgery, Kobe City Medical Center West Hospital, Kobe, Japan
16) Department of Health Informatics, Kyoto University School of Public Health, Kyoto, Japan
17) Department of Pharmacoepidemiology, Graduate School of Medicine and Public Health, Kyoto, Japan
18) Department of Clinical Biostatistics, Graduate School of Medicine, Kyoto University, Kyoto, Japan

Yusuke Fujita¹⁾, Tatsuto Nishigori¹⁾, Norihiro Shimoike¹⁾, Katsuhiro Murakami¹⁾, Yoshio Kadokawa²⁾, Atsushi Itami³⁾, Masato Kondo⁴⁾, Seiichiro Kanaya⁵⁾, Hironori Kawada⁶⁾, Hiroaki Hata⁷⁾, Michihiro Yamamoto⁸⁾, Yousuke Kinjo⁹⁾, Eiji Tanaka¹⁰⁾, Dai Manaka¹¹⁾, Seiji Satoh¹²⁾, Hiroshi Okabe¹³⁾, Yoshito Yamashita¹⁴⁾, Takatsugu Kan¹⁵⁾, Yoshihito Goto¹⁶⁾, Takeo Nakayama¹⁶⁾, Koji Kawakami¹⁷⁾, Shiro Tanaka¹⁸⁾, Shigeo Hisamori¹⁾, Shigeru Tsunoda¹⁾, Koya Hida¹⁾, Kazutaka Obama¹⁾