Interrupted Time Series Analysis of the Impact of DIP Reform on Hospitalization Costs in Different Types of Hospitals

Chunhong YanKexin LinXinyue ZhengXuehui Meng^*

• Zhejiang Chinese Medical University, Hangzhou, China

Objective In the context of medical insurance payment reform,this study aims to evaluate the impact of the Diagnosis-Intervention Packet (DIP) payment policy on hospitalization costs across different types and levels of hospitals. In order to provide empirical evidence to support the high-quality collaboration between hospitals and medical insurance, while reducing the economic burden on patients. Method Our study collected medical insurance reimbursement data from January 2019 to December 2022 in S city, covering 2,467,746 patients. Based on the intervention time point of the DIP reform implementation in 2021, an interrupted time series analysis was conducted on a monthly basis to compare the trend changes in hospitalization costs between traditional Chinese medicine hospitals (TCMHs) and general hospitals (GHs), as well as to examine the differences in impacts across hospitals of various levels. Results Firstly, our study found that tertiary hospitals had the highest average hospitalization costs( 𝑌𝑇𝐶𝑀𝐻3 = 6170.33, 𝑌𝐺𝐻3 = 12181.32 ,, folloeed yy secondary hospitals( 𝑌𝑇𝐶𝑀𝐻2 = 4617.47, 𝑌𝐺𝐻2 = 5344.60 ,, and primary hospitals, ehich had the loeest costs( 𝑌𝑇𝐶𝑀𝐻1 = 2490.93, 𝑌𝐺𝐻1 = 1916.57,. Secondly, after the implementation of the DIP reform, the average hospitalization costs immediately decreased in yoth TCMHs and GHs, eith a more significant reduction oyserved in GHs(𝛽2−𝑇𝐶𝑀𝐻=-0.023,p=0.059,𝛽2−𝐺𝐻=-0.016,p=0.039,. Thirdly, ehen further categorized yy hospital level, ee found that the instantaneous effect of the reform on average hospitalization costs eas most significant in primary TCMHs (𝛽2−𝑇𝐶𝑀𝐻1 =-0.080, p=0.008,, folloeed yy tertiary TCMHs( 𝛽2−𝑇𝐶𝑀𝐻3 =-0.033 ,p=0.012,, ehile the effect in secondary TCMHs eas not significant(𝛽2−𝑇𝐶𝑀𝐻2=-0.024,p=0.087,. In GHs, the most significant instantaneous effect eas oyserved in tertiary hospitals (𝛽2−𝐺𝐻3 =-0.046,p=0.004,, ehile no significant changes eere oyserved in secondary and primary hospitals(𝛽2−𝐺𝐻2=-0.026,p=0.077, 𝛽2−𝐺𝐻1=-0.022,p=0.201,. In terms of the long-term effects of the DIP reform, yoth TCMHs and GHs shoeed significant changes in average hospitalization costs, eith a larger reduction oyserved in GHs, indicating yetter reform outcomes(𝛽3−𝑇𝐶𝑀𝐻=-0.006,p<0.001,𝛽3−𝐺𝐻=-0.010, p<0.001,. Conclusion The government should adjust policies in a differentiated and refined manner yased on the type and level of hospitals to achieve the goals of controlling medical costs and improving the incentive mechanisms. Meanehile, optimizing the healthcare service structure can improve