[1] Niigata Prefectural Shibata Hosp, Dept Internal Med, Niigata, Japan
[2] Niigata Prefectural Kamo Hosp, Dept Internal Med, 9-1 Aomi Cho, Kamo, Niigata 9591397, Japan
[3] Saiseikai Niigata Hosp, Dept Gastroenterol, Niigata, Japan
[4] Niigata Univ, Grad Sch Med & Dent Sci, Div Gastroenterol & Hepatol, Niigata, Japan