醫療提供者之行為策略－－賽局理論之應用

Applying Game Theory to Analyze Health Care Providers’ Strategies under Global Budget

本文以賽局理論作為分析基礎，探究總額預算支付制度下，各醫療服務提供者的可能行為策略及其報酬組合，並比較均衡解下的醫療服務總量和整體醫療機構之最佳醫療服務量。最後探討總額預算支付制是否影響民眾就醫權利以及醫療服務品質。結果發現：1.在靜態以及動態有限期雙人賽局的情況下，醫療機構選擇高服務量是優勢策略(dominant strategy)。但在動態無限期的雙人賽局中，亦即總額預算制度持續實施的情況下，若醫療提供者彼此間同儕制約的力量夠大時，則可達到（低服務量，低服務量）的子賽局精煉Nash 均衡。2.在多人單期賽局中，若健保局至少給付某最低點值以使醫療機構維持最基本的醫療品質時，則高服務量優勢策略下的醫療服務均衡總量大於整體醫療機構之最佳醫療服務量，而導致點值下降，形成共有資源悲劇。3.若支付標準設計不當，易引發醫療機構的道德風險效果(moral hazard effect)和風險選擇效果(risk selection effect)，使得醫療品質下降、醫療資源浪費並造成各醫療部門之發展嚴重扭曲的現象。

The purpose of this paper is to characterize the Nash equilibrium service quantities under the global budget cap system using the game theoretical analysis. This paper investigates the provider’s strategy under global budget cap with one-period, finite and infinite two-person game framework. In addition, we also employ multi-person game to compare the medical service quantities between the Nash equilibrium and the social optimum. Furthermore, this paper also explores the effects of the global budget cap system on the accessibility and quality of health care. Under the prospective payment system, the provider’s total budget for the coming year is set in advance. The size of the budget represents a spending ceiling. Providers are allowed considerable flexibility to make decisions within the budget limit. According to a negotiated relative value scale, a point schedule is established assigning different points to the corresponding health care services. The budget is then divided by total points accumulated at the end of budget year and the relative value unit of health service is thus determined. Each provider’s income is attained by multiplying his own accumulated points and the relative value unit given by the above calculation. It is obvious that the quantity decisions of all providers combined determine the relative value unit which is automatically reduced if every provider chooses to supply more health services. Thus, a provider aims at increasing his own profits by increasing health services quantities may results in an adverse consequences of decreasing profits due to the decreased relative value unit. A global budget creates an interest conflict among providers. The results of the model analysis are as follows: First, choosing high service quantities is the dominant strategy for health care providers under one-period and finite two-person game. Nonetheless, low service quantities may become the sub-game perfect Nash equilibrium under infinite repeated game with each provider implement Nash reversion strategy. Second, subject to the minimum value unit stipulated by the regulator, the dominant strategy of high service quantities results in larger service quantities and smaller value unit than those at collective optimum under one-period multi-person game. Finally, problems of moral hazard and risk selection may occur if the value unit as well as the points schedule is improperly designed. As a result, the quality of health care may be decreased, medical resources may be over utilized, and development for medical departments may be distorted seriously.