Trend analysis of medical expenses under DRG payment reform in China

The impact and evolving trends of Diagnosis-Related Group (DRG) payment reform on inpatient medical expenses have drawn substantial academic and societal attention. However, there remains a notable gap in research focusing on the cost-control efficacy and its dynamic trends under this reform. Employing Mann–Whitney U testing, structural change analysis, and interrupted time-series methods, this study quantifies pre-post DRG reform shifts in inpatient expenditures, insurance compensation patterns, and expenditure trajectories. The results showed that per capita hospitalization expenses decreased 713.93 yuan (β 1 + β 3 = − 713.93, p < 0.001) per month, with monthly medical insurance payments declining 0.82% (β 1 + β 3 = − 0.82, p < 0.01) versus 0.82%, monthly out-of-pocket expenses increases (β 1 + β 3 = 0.82, p < 0.01). In cost structure, the structural change in hospitalization costs was 4.37%, which pharmaceutical, health material, laboratory and medical service costs declined while examination costs rose significantly ( p < 0.01). While DRG payment reform reduces certain hospitalization costs, out-of-pocket expenses for patients have increased, highlighting ongoing financial challenges. Drug and material expenses remain primary cost drivers, whereas medical service fees are undervalued. Future reforms must prioritize clinical expertise recognition, optimize insurance fund efficiency, and lower patient copayments to balance affordable care, hospital viability, and financial sustainability.