Spatial mismatch and hierarchical optimization of healthcare facilities: a multi-source geospatial analysis of accessibility and supply-demand dynamics

In rapidly urbanizing megacities, the allocation of healthcare resources has long faced the dual challenges of spatial inequity and insufficient hierarchical diagnosis and treatment systems. This study constructed a multi-scale spatial analysis framework in Nanjing, China, to systematically diagnose the supply-demand mismatch of healthcare resources. By integrating the community-level detailed units and 100-meter population raster data, we combined the Hierarchical Two-Step Floating Catchment Area (H2SFCA) method with empirically calibrated service radii and introduced the "per capita bed compliance rate" to address the contradictions between "statistical adequacy" and "functional efficiency" in high-density clusters. The study revealed three key findings: First, medical resources in Nanjing present a "core-periphery" mismatch structure, tertiary hospitals are over-concentrated in the urban core (HH cluster), while per capita bed availability falls below the threshold (0.8 beds per thousand people), posing a hidden risk of overload. Second, secondary hospitals demonstrate a double paradox (LH-type shortages in old city and HL-type excesses in the suburbs), while the primary facilities fail to serve 32.57% of high-demand communities, contrasting sharply with inefficient HL-type redundancies found in remote suburbs. Additionally, 5% of transitional areas show statistically insignificant supply-demand correlations due to the disconnect between population mobility and static data. Based on these insights, the study proposes a two-path optimization framework-"Targeted interventions by LISA cluster type + hierarchical coordination (via referral networks)"-which offers an actionable pathway toward precision-oriented resource allocation. This approach not only provides practical solutions for establishing a"15-minute medical circle" in Nanjing but also presents a methodological paradigm applicable to high-density cities worldwide seeking effective strategies for hierarchical diagnosis and treatment.