Impact of Chinese national centralized volume-based drug procurement policy on health costs and utilization: An interrupted time series analysis using panel data (2009–2022)

Chinese national centralized volume-based drug procurement policy has significantly reduced drug prices but initially increased non-drug costs. Regional disparities linked to aging demographics and complementary reforms (e.g., Diagnosis Related Group) shaped outcomes, while COVID-19 temporarily suppressed utilization. Future policy optimization should integrate Diagnosis Related Group payment reforms with regionally tailored strategies to balance cost containment and service quality. We recommend enhancing temporal resolution and extending observation periods to enable more precise policy evaluation.