1 Department of Clinical Epidemiology and Health Economics, School of Public Health, University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo, Japan yamana-tky@umin.ac.jp.
2 Department of Clinical Epidemiology and Health Economics, School of Public Health, University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo, Japan.