Objectives: This study aims to examine the impact of Diagnosis-Related Group (DRG) payment on medical costs, efficiency, and quality of healthcare services in public hospitals, providing policy recommendations for further health insurance payment reforms in China. Methods: Utilizing inpatient medical insurance settlement data from 2020 to 2023 in the selected city, we constructed a regression discontinuity design (RDD) and an interrupted time series (ITS) model to evaluate the causal effects of the DRG reform. The analysis includes 66,533 inpatient settlement records. Results: Following the reform, the average length of stay (LOS) decreased by 2 days (95% CI: −3.43 to −0.70, p < 0.01), total hospitalization expenditures dropped by 13% (95% CI: −0.26 to −0.00, p < 0.05), and expenditures from the medical insurance fund declined by 25% (95% CI: −0.39 to −0.12, p < 0.01). Additionally, examination and consultation fees were reduced by 23% (95% CI: −0.41 to −0.05, p < 0.05), although patients’ out-of-pocket burden increased by 8% (95% CI: 0.05 to 0.10, p < 0.01). In terms of healthcare quality, the 30-day readmission rate decreased by 1% (95% CI: −0.01 to −0.00, p < 0.01), and the mortality rate among low-risk patients declined by 4% (95% CI: −0.04 to −0.03, p < 0.01). We found no evidence of patient selection or denial of admission. Heterogeneity analysis revealed that the reduction in hospital stay was concentrated among enrollees under the Urban and Rural Resident Basic Medical Insurance and those treated in secondary hospitals. The policy’s effects peaked shortly after implementation but gradually attenuated over time. Conclusions: Our study offers hospital-level evidence indicating that the initial stage of DRG implementation achieved its preliminary goals of optimizing medical resource allocation and improving the efficiency of medical insurance fund utilization. However, the reform still faces several challenges. These findings may offer valuable references for developing countries pursuing reforms in primary healthcare and health insurance payment systems.

Objective: This study examines the effect of DRG payment reform on nutritional therapy costs, hospitalization expenditures, and resource utilization among gastric cancer surgery patients using a quasi-experimental design. Methods: We conducted an interrupted time series analysis using inpatient data from a tertiary hospital in a major Chinese city between January 2018 and December 2024, including 761 gastric cancer surgery patients. Segmented regression models estimated changes in baseline trend, immediate level, and post-intervention slope for nutritional therapy expenditures, total hospitalization costs, surgical fees, and length of stay. Subgroup analyses were performed by type of medical insurance, and robustness checks were conducted. Results: Following DRG implementation, enteral nutrition costs showed a significant immediate increase (β₂ = 395.703, p = 0.032) followed by a significant downward slope change (β₃ = −7.778, p = 0.032). Total hospitalization costs demonstrated a significant immediate rise (β₂ = 15,959.403, p = 0.019) and subsequent decline (β₃ = −632.069, p < 0.001). Parenteral nutrition costs exhibited a significant immediate reduction (β₂ = −2917.276, p = 0.001) without sustained trend changes. Surgical fees showed a significant downward baseline trend (β₁ = −39.951, p < 0.001) and a significant upward slope change (β₃ = 68.107, p < 0.001). Subgroup analyses revealed that policy effects were concentrated among patients with Urban Employee Basic Medical Insurance, with no significant effects observed for those with Urban and Rural Resident Basic Medical Insurance. Robustness checks confirmed the main findings. Conclusions: DRG payment reform significantly reshaped nutritional therapy and hospitalization expenditure patterns among gastric cancer surgery patients, with effects concentrated in the employee insurance population. The observed temporal pattern, characterized by an initial change followed by a gradual trend shift, suggests the need for continuous policy monitoring, insurance-tailored strategies, and refinement of nutritional support practices within DRG frameworks.