1. Department of Orthopaedic Surgery, The
University of Tokyo, Graduate School of Medicine, 7-3-1, Hongo, Bunkyo-ku, Tokyo, Japan.
2. Department of Clinical Epidemiology and
Health Economics, School of Public Health, The
University of Tokyo 7-3-1, Hongo, Bunkyo-ku, Tokyo, Japan.
3. Department of Clinical Data Management
and Research, Clinical Research Center, National
Hospital Organization Headquarters, 2-5-21
Higashigaoka, Meguro-ku, Tokyo, Japan.
4. Department of Health Policy and Informatics, Tokyo
Medical and Dental University Graduate School of Medicine 1-5-45
Yushima, Bunkyo-ku, Tokyo, Japan