[1] Univ Tokyo, Grad Sch Med, Dept Gastroenterol, Bunkyo Ku, 7-3-1 Hongo, Tokyo 1138655, Japan
[2] Univ Tokyo, Sch Publ Hlth, Dept Clin Epidemiol & Hlth Econ, Bunkyo Ku, 7-3-1 Hongo, Tokyo 1130033, Japan
[3] Natl Hosp Org Headquarters, Clin Res Ctr, Dept Clin Data Management & Res, Meguro Ku, 2-5-21 Higashigaoka, Tokyo 1528621, Japan
[4] Tokyo Med & Dent Univ, Grad Sch Med, Dept Hlth Policy & Informat, Bunkyo Ku, 1-5-45 Yushima, Tokyo 1138510, Japan