To analyze the effect of diagnosis related group(DRG) reform in 2022 and its impact on patients in different departments, and create a policy environment that promotes the implementation of DRG.

The data of this study were collected from the database of discharge records of secondary and tertiary hospitals in Beijing, including 1 603 989 discharge records of urban employee medical insurance inpatients. This study constructed a difference in difference model and used the event study method to test the parallel trend assumption. Firstly, the hospital-month level aggregated data was used to analyze the effects of DRG reform on inpatient cost per admission, average length of stay, proportion of patients with 30-day read-mission, proportion of patients with 60-day readmission and the proportion of patients admitted through outpatients. Then, the aggregated monthly data of the departments of internal medicine, surgery, obstetrics and gynecology and oncology were used to further analyze the influence of DRG reform on the utilization of inpatient services in different departments.

DRG reform reduced the inpatient cost per admission by about 9.79% and the length of stay per admission by about 5.35%, but had no significant effect on readmission risk and the proportion of patients admitted through outpatients. It reduced the inpatient cost per admission in the departments of internal medicine, surgery and obstetrics and gynecology, and reduced the length of stay per admission of inpatients in the departments of internal medicine and surgery. However, the reform had no significant effect on the readmission risk and the proportion of patients admitted through outpatients for all the four departments.

The DRG reform in Beijing reduced the inpatient cost per admission, but it is necessary to regularly monitor the medical behavior and pay more attention to the role of other payment methods in making up for the deficiencies of DRG. The impact of DRG reform on different departments is varied, so appropriate supportive policies should be formulated to secure the beneficial development of DRG reform.