[1] Hokkaido Univ, Sch Med, Dept Gastroenterol & Hematol, Kita Ku, Sapporo, Hokkaido 0608638, Japan
[2] Aiiku Hosp, Dept Internal Med, Sapporo, Hokkaido, Japan
[3] Hakodate Cent Hosp, Dept Internal Med, Hakodate, Hokkaido, Japan
[4] Sapporo Kousei Hosp, Dept Internal Med 2, Sapporo, Hokkaido, Japan
[5] Asahikawa Kousei Hosp, Dept Internal Med, Asahikawa, Hokkaido, Japan
[6] Hokkaido Canc Ctr Hosp, Dept Hematol, Sapporo, Hokkaido, Japan
[7] Obihiro Kousei Hosp, Dept Internal Med 4, Obihiro, Hokkaido, Japan