Spatial structure and mechanism of cross-city patient mobility network in the Yangtze River economic belt of China

Cross-city patient mobility reflects the geographic mismatch in medical resources, posing significant challenges for healthcare accessibility and equitable resource allocation. However, existing research methods inadequately capture the complex relationships between healthcare supply and demand as well as the proximity mechanisms influencing patient mobility. In this study, we used 500,120 patient online evaluations to build the 2023 Cross-city Patient Mobility Network (CPMN) for the Yangtze River Economic Belt (YREB), and analyzed its spatial structure and influencing factors using healthcare relative size index, dominant association analysis, and explainable machine learning modeling. The results show that: (1) There is a double logarithmic linear relationship between healthcare supply size and intensity (coefficient 0.627), and a weak negative correlation between demand size and intensity; (2) While the spatial organization of healthcare aligns with administrative boundaries and hierarchies, exceptions are observed in parts of Shanghai and Chongqing's healthcare catchment areas; (3) Social proximity, geographical proximity and institutional proximity are significant in patient mobility. This research contributes new data and methods to health geography and offers theoretical and empirical insights critical for optimizing healthcare resource allocation in the YREB, ultimately addressing the challenges of equitable healthcare access.