1. Department of Clinical Epidemiology and Health Economics, School of Public Health, University of Tokyo, Hongo, Bunkyo-ku, Tokyo, Japan.
2. Department of Health Services Research, University of Tokyo, Hongo, Bunkyo-ku, Tokyo, Japan.
3. Department of Health Policy and Informatics, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Yushima, Bunkyo-ku, Tokyo, Japan.