1. Department of Pediatric Surgery, Graduate School of Medicine, The University of Tokyo, Bunkyo-ku, Japan
2. Department of Pediatric Surgery, National Center for Child Health and Development, Setagayaku, Tokyo, Japan
3. Department of Health Services Research, Graduate School of Medicine, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
4. Department of Clinical Epidemiology and Health Economics, School of Public Health, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
5. Department of Health Policy and Informatics, Tokyo Medical and Dental University Graduate School, Bunkyo-ku, Tokyo, Japan
6. Department of Pediatric Surgery, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan