The Impact of DRG Payments on Nutritional Therapy Costs for Gastric Cancer Surgery Patients

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.