Abstract: This study investigates the causes of increasing medical costs from the aspects of concentration and persistence. Counterfactual calculation shows that population ageing increases medical expenses at different subpoints and narrows the distribution gap of medical expenses, which are caused by the high concentration and persistence of medical expenses of the older population. The medical cost of the older population is not only characterized by a high amount of single hospitalization cost, a large proportion of continuous hospitalization, and a strong dispersion of medical cost, but also induces a heavier burden in all of the five levels of medical cost. The influence of population ageing to the increase of medical costs is lower than that of the change of the whole population age structure. The influence of endowment effect increases with time, and the medical costs of high percentiles increase the most. In addition, the improvement of health awareness plays a dominant role in the structural effects that affect the growth of medical costs. The theoretical framework constructed in this study which describes how the medical demand of the aged population affects the medical cost can explain the reality of the rapid growth of medical cost under the background of population ageing in China.

Keywords: Population Ageing, Medical Expenses, Concentration, Influential

摘要： 从集中度和持续性层面考察人口老龄化增加医疗费用的成因。反事实测算发现人口老龄化增加不同分位点医疗费用支出，缩小医疗费用分配差距这一重要事实，其根源是老年人口医疗费用的高集中度和强持续性。老年人口医疗费用不仅具有单次住院费用高、持续住院比例大、医疗费用分散性强的特点，而且在5个医疗费用层次内支出负担更重。人口老龄化对医疗费用增长的影响力低于全体人口年龄结构变动的影响力，禀赋效应的影响力随时间推移上升，高分位医疗费用上升幅度最明显。此外，健康意识的提高在影响医疗费用增长的结构效应中占据主导地位。通过构建老年人口医疗需求影响医疗费用的理论逻辑，有力解释了中国人口老龄化背景下医疗费用快速增长的现实。

关键词: 人口老龄化, 医疗费用, 集中度, 影响力