The Theoretical and Experimental Study on Reform of Payment System for Reimbursement to Medical Institutions

针对医疗奖励的DRG-PPS(Dyagoses Related Group And Prospective Payment System)已被引入美国和其他国家，以降低国家医疗成本，特别是医院支付。日本当局还计划将DRG-PPS适应现有的医疗奖励制度。然而，日本医疗市场的竞争是最激烈的，因为患者可以自由选择和更换他们访问的任何医院。因此，要分析引入DRG-PPS对日本医疗市场的影响需要一个动态框架，使患者能够重复选择医院。在本项目中，我们调查了1)DRG-PPS的引入是否降低了人均医疗服务水平，2)医疗费用的补偿成本是否在随后的时期内发生了波动，以及3)什么样的医疗支付系统满足任何最优的医疗服务供给。总结结果，第一，无论每家医院具有不同的代理人系数，稳态提供的人均卫生保健服务水平都是相同的。接下来，当我们考察动态路径收敛到均衡的时候，我们可以发现医疗补偿成本的回升。补偿成本的回升意味着稳定状态下的补偿成本比引入DRG-PPS的次日要大得多。这种现象出现在一些医院过分尊重患者利益而不是医院利润的情况下。最后，在一定条件下，存在一种综合支付制度，以最大化患者的净利益，从患者通过接受医疗保健获得的利益中扣除医疗成本。

DRG-PPS (Dynagoses Related Group and Prospective Payment System) for medical rewards has been introduced to the United States of America and other countries reducing national medical costs, especially hospital payments.The Japanese authority also plans to adapt DRG-PPS to the existing medical reward system. However, the Japanese market for health care is characterized by the most severe competition among hospitals since patients can freely choice and change any hospital that they visit.Therefore, to analyze effects concerning an introduction of DRG-PPS into the Japanese health market needs a dynamic framework possible to that patient choices hospital repeatedly.In this project, we investigate1) whether the introduction of DRG-PPS decreases a per capita service level of health care or not,2) whether any swingback of reimbursement cost for health care happened in the periods that follow it or not,and 3) what kind of medical payment system fulfills any optimal supply for health care.Summarizing the results, first, the per capita service level of health care supplied in steady state is the identical to every hospital, regardless of that each hospital has a different agent coefficient. Then the introduction of DRG-PPS happen to decrease the service level of health care relatively to under Fee-for-Service.Next, when we investigate dynamic paths to converge on equilibrium, we can find the swingback of reimbursement cost for health care. The swingback of reimbursement cost means that reimbursement cost in steady state becomes much larger than in the morrow of introducing DRG-PPS. This phenomenon arises when some hospitals extremely respect patient benefit rather than hospital profit.Finally, under certain condition, there is a composite payment system to maximize the net benefit for patient that deducts a medical cost from a patient benefit gained by receiving health care.