[1] Ehime Univ, Dept Hepatopancreaticobiliary & Transplant Surg, Grad Sch Med, Toon City, Ehime 7910295, Japan
[2] Tohoku Univ, Grad Sch Med, Dept Phys Med & Rehabil, Sendai, Miyagi 980, Japan
[3] Kyoto Univ, Grad Sch Med, Dept Surg, Kyoto, Japan
[4] Kyoto Univ, Grad Sch Med, Dept Healthcare Epidemiol, Kyoto, Japan
[5] Tokyo Womens Med Univ, Inst Gastroenterol, Dept Surg, Tokyo, Japan
[6] Yokohama City Univ, Med Ctr, Dept Biostat & Epidemiol, Yokohama, Kanagawa 232, Japan
[7] Fdn Kobe Int Med Alliance, Kobe, Hyogo, Japan