[1] Iwate Med Univ, Sch Med, Dept Internal Med, Div Gastroenterol & Hepatol, Yahaba, Japan
[2] Iwate Prefectural Cent Hosp, Dept Gastroenterol, Morioka, Iwate, Japan
[3] Tohoku Univ, Div Gastroenterol, Grad Sch Med, Sendai, Miyagi, Japan
[4] Sendai City Med Ctr, Dept Gastroenterol, Sendai, Miyagi, Japan
[5] Akita Univ, Dept Gastroenterol & Neurol, Grad Sch Med, Akita, Japan
[6] Hiraka Gen Hosp, Dept Gastroenterol, Akita, Japan
[7] Yamagata Univ, Fac Med, Dept Gastroenterol, Yamagata, Japan
[8] Yamagata Prefectural Cent Hosp, Dept Gastroenterol, Yamagata, Japan
[9] Hirosaki Univ, Dept Gastroenterol & Hematol, Grad Sch Med, Aomori, Japan
[10] Aomori Prefectural Cent Hosp, Dept Gastroenterol, Aomori, Japan
[11] Fukushima Med Univ Hosp, Dept Endoscopy, Fukushima, Japan
[12] Iwate Med Univ, Sch Med, Dept Internal Med, Div Gastroenterol & Hepatol, 2-1-1 Idaidori, Yahaba, Iwate 0283695, Japan