The impact of diagnosis-intervention packet (DIP) payment on cost structure of inpatient care—Evidence from a tertiary hospital in China

Background Since 2020, China has implemented DIP (Diagnosis-Intervention Packet) payment reform to control medical costs and reduce patient financial burden. The reform was piloted in a representative tertiary public hospital within a provincial DIP pilot city. Methods The study used hospital settlement and medication records from January 2019 to June 2023. Interrupted time series analysis (ITSA) and structural change degree (SCD) were applied to evaluate the impact of DIP reform on weekly per capita costs and cost structures for surgical and non-surgical groups. Synergistic effects of health system reforms were also assessed. Results From January 2019 to June 2023, total costs for surgical and non-surgical groups decreased by 3.42% and 1.25%, respectively. Drug and surgical costs declined significantly (p < 0.05) in both groups, while consumable costs increased significantly (p < 0.05). The growth rate of total costs slowed (surgical group: β 3 = −14.10; non-surgical group: β 3 = −10.76). Total costs in the non-surgical group showed a decreasing trend post-DIP intervention (β 1 + β 3 = −3.12). Drug costs (surgical group: β 3 = −5.50; non-surgical group: β 3 = −4.11) and inspection costs (surgical group: β 3 = −3.57; non-surgical group: β 3 = −1.73) decreased in both groups. Structural change analysis showed a degree of structural variation (DSV) of 10.34% for the surgical group and 5.60% for the non-surgical group. Contribution rates of structural variation (CSV) indicated significant contributions from consumable costs (CSV = 55.83%) and drug costs (CSV = 36.02%) in the surgical group, and inspection costs (CSV = 48.75%) in the non-surgical group. Conclusion DIP payment reform led to positive outcomes in the cost structure of inpatient care. However, increases in inspection costs and differences in cost structures between groups need further attention. Future efforts should focus on more precise cost management.