Designing New Systems Through Risk Adjustment

  • Yasushi Iwamoto


Public health insurance for Japan’s working generations is divided into several systems. There are disparities among these systems in terms of their state of financing due to differences in the income level of premium payers. The state of financing of National Health Insurance is particularly problematic. Risk adjustment can adjust disparities in premiums without hindering the management efforts of insurers. This would make it possible to adjust disparities in premiums arising from factors such as the age structure and income level of subscribers, which cannot be controlled by insurers, while disparities due to other factors would still occur. The introduction of risk adjustment to the National Health Insurance system could be expected to resolve the system’s financial problems.


Public health insurance Kyokai Kenpo National Health Insurance Disparity in financing Risk adjustment Age-related risk Incentive for insurers Reduction of medical costs 


  1. Iwamoto, Yasushi (1996), “Shian: Iryohokenseido Ichigenka (Designing an Integration of Health Insurance Groups),” Nihon Keizai Kenkyu (JCER Economic Journal), No. 33, November, pp. 119–142 (included in Hatta, Tatsuo, and Yashiro, Naohiro (eds.) (1998), “Shakaihoken Kaikaku (Social Insurance Reforms),” Shirizu gendai keizai kenkyu 16 (Contemporary Economic Study Series Vol. 16), Nihon Keizai Shimbun) (in Japanese).Google Scholar

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© The Author(s) 2018

Authors and Affiliations

  • Yasushi Iwamoto
    • 1
  1. 1.Graduate School of EconomicsUniversity of TokyoTokyoJapan

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