目的：医保支付方式改革是撬动我国医疗体制改革的重要支点。2021年3月15日北京市正式进行CHS-DRG支付方式的付费阶段。本研究以此为契机，从医疗费用、医疗质量及医疗效率三个维度分析北京地区CHS-DRG的实施效果评价，探究该政策对使用该支付方式以及未使用该支付方式患者的重要影响。方法：本研究以2021年9月1日至2022年9月30日为观察周期，选取北京市某三级甲等医院102753人次的住院记录为研究对象，基于是否使用CHS-DRG支付方式将患者分为DRG组和对照组，基于改革实施时间节点2021年3月15日前后将患者分为干预实施前与干预实施后。指标方面，选取年龄与性别为人口学特征指标，选取住院费用、耗材费、药费、检查化验费、手术费、治疗费用、其他费用以及其对数为医疗费用维度指标，选取病死率为医疗质量维度指标，选取住院天数与超长住院为医疗效率维度指标。以双重差分法与中断时间序列分析为分析方法，探讨DRG组与对照组在政策干预前后相关指标的变化，评价CHS-DRG政策实施效果。结果：双重差分法结果表明，相对于对照组，DRG组在政策干预后医疗费用显著降低、医疗效率显著提升（P<0.001），但医疗质量未发生显著变化（P=0.364）；中断时间序列分析进一步揭示了，DRG组医疗质量长期而言存在显著降低的趋势（P=0.049），对照组医疗效率受到政策干预的溢出效应影响出现了显著下降（P<0.001）。结论：CHS-DRG政策的实施显著地降低医疗费用、提升医疗效率，但长期而言，可能会危害到这些患者的医疗质量。此外，研究还发现，CHS-DRG政策的实施可能存在溢出效应，波及非DRG支付的患者，导致这些患者医疗效率降低，但并未发现这些患者的医疗费用出现补偿性上升。

Objective: The reform of medical insurance payment methods is an important lever for driving the reform of China‘s medical system. On March 15, 2021, Beijing officially launched the CHS-DRG payment system for medical reimbursements. This study analyzes the implementation and evaluate the effectiveness of CHS-DRG payment system in Beijing from three dimensions: medical expenses, medical quality, and medical efficiency, and explore the important impact of this policy on patients.Methods: This study takes the period from September 1, 2021, to September 1, 2022, as the observation period, and selects the hospitalization records of 102,753 patients from a tertiary hospital in Beijing as the research object. Based on whether CHS-DRG payment method was used or not, patients were divided into intervention and control groups. Based on the implementation time of the reform, patients were further divided into pre-intervention and post-intervention groups around March 15, 2021. Demographic characteristics such as age and gender were selected as the population indicators, and hospitalization costs, consumables costs, medication costs, laboratory testing costs, surgical costs, treatment costs, other costs, and their logarithms were selected as the medical expenses indicators. Death rate was selected as the medical quality indicator, while length of stay and prolonged hospitalization were selected as the medical efficiency indicators. Using the difference-in-differences method and interrupted time series analysis as the analytical methods, this study explores the changes in relevant indicators between the intervention and control groups before and after policy intervention, and evaluates the effectiveness of the CHS-DRG policy implementation.Results: The results of the doubly-differenced method show that, compared to the control group, the intervention group experienced a significant reduction in medical expenses and a significant improvement in medical efficiency (P<0.001) after policy intervention, but there was no significant change in medical quality (P=0.364). Interrupted time series analysis further revealed a significant long-term trend of decreased medical quality in the intervention group (P=0.049), and a significant decline in medical efficiency in the control group due to the spillover effect of policy intervention (P<0.001).Conclusion: The implementation of the CHS-DRG policy significantly reduced medical expenses and improved medical efficiency, but in the long run, it may harm the medical quality of these patients. In addition, the study also found that the implementation of the CHS-DRG policy may have spillover effects, affecting patients who are not paid under the DRG system, leading to a decrease in their medical efficiency, but no compensatory increase in their medical expenses was found.