[1] Keio Univ, Sch Med, Dept Internal Med, Div Gastroenterol & Hepatol, Tokyo 1608582, Japan
[2] Kawasaki Med Sch, Dept Internal Med, Div Gastroenterol, Okayama, Japan
[3] Nagoya City Univ, Grad Sch Med Sci, Dept Gastroenterol & Metab, Nagoya, Aichi, Japan
[4] Nippon Med Sch, Dept Internal Med, Div Gastroenterol, Tokyo 113, Japan
[5] Kyorin Univ, Sch Med, Dept Internal Med 3, Tokyo, Japan
[6] Natl Hosp Org, Tokyo Med Ctr, Div Gastroenterol, Tokyo, Japan
[7] Tokyo Saiseikai Cent Hosp, Dept Internal Med, Tokyo, Japan
[8] Univ Tokyo, Grad Sch Med, Sch Publ Hlth, Dept Social & Prevent Epidemiol, Tokyo, Japan