Influence of Copayment on Health Service Utilization: Analyses Considering Age, Income, and Diseases

2020 Fiscal Year Final Research Report

• Project/Area Number: 18H03021
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 58010:Medical management and medical sociology-related
• Research Institution: The University of Tokyo
• Principal Investigator: KOBAYASHI YASUKI 東京大学, 大学院医学系研究科(医学部), 教授 (70178341)
• Project Period (FY): 2018-04-01 – 2021-03-31
• Keywords: 医療保険 / 介護保険 / 自己負担 / 受療行動 / レセプト / 自然の実験

Outline of Final Research Achievements

Using claims data and econometric methods, the following results were obtained. (1) Income-based co-payment rates appeared to reduce disparity in access to brand-name drugs across income groups, in addition to reducing total medical expenditures among high-income group. (2) Both inertia and heterogeneity in brand preferences have substantial effects on the choice of brand-name pitavastatin or generic ones. Counterfactual simulations suggest that a nudging policy that removes inertia from previous brand-name users may have substantial effects and enable patients to choose optimally. (3) Regarding the impacts of medical subsidy for children, no significant effect of the stop-loss policy on health services expenditures was observed, while the free prescription policy significantly increased prescription drug expenditures among children with relatively good health status. The stop-loss policy for children is potentially efficient in terms of the policy of medical subsidy for children.

Free Research Field

医療政策学

Academic Significance and Societal Importance of the Research Achievements

医療費の自己負担の要点は、必要な受療を抑制せずに、不要な受療を減らすことのできる適切な負担額の設定である。自己負担の効果は、患者の年齢、疾患の種類や重症度、所得などにも影響される。しかし、わが国では、種々の交絡要因の調整が可能な個票データを用いて、自己負担の影響をみた研究はきわめて少ない。本研究は、レセプトデータと計量経済学的手法を用いて、後期高齢者制度における自己負担率やInertiaと後発医薬品選択割合の関連、子ども医療費助成や介護保険の自己負担の影響を量的に明らかにした研究であり、独創性が高い。今後のわが国の医療経済・医療政策研究の発展ならびに実際の政策形成に資するものと考えられる。