Impact of spatial accessibility to primary care physicians on health care outcomes and costs

Abstract Background This study is the first in Taiwan to apply the enhanced two-step floating catchment area (E2SFCA) method to evaluate the spatial accessibility of primary care. Traditional physician-to-population ratios by administrative region overlook cross-boundary healthcare-seeking and travel distance barriers. This study accounts for these limitations and further examines the impact of accessibility on healthcare utilization and outcomes. Methods We used national health insurance claims, physician registry data, and GIS-based road networks to measure accessibility with the E2SFCA method, defining it as the number of primary care physicians per 10,000 residents within a 30-minute travel time. A retrospective cohort of 2 million adults was analyzed. Generalized estimating equations with appropriate regression models assessed associations between accessibility and healthcare utilization, expenditures, avoidable emergency department (ED), and avoidable hospitalizations. Results Spatial analysis identified 15 townships (114,915 residents, 0.49%) with no primary care physicians and another 15 townships (114,430 residents, 0.49%) with low accessibility. These underserved areas were concentrated in central and eastern Taiwan, whereas metropolitan regions had sufficient resources. Higher accessibility was significantly associated with fewer ED visits (ratio = 0.994; 95% CI: 0.990–0.997, P< 0.001), ED expenditures (ratio = 0.993; 95% CI: 0.989–0.997, P< 0.001), the odds of avoidable ED visits (odds ratio = 0.993; 95% CI: 0.988–0.998, P = 0.005), and the number of avoidable ED visits (ratio = 0.993; 95% CI: 0.988–0.998, P = 0.004). Accessibility also reduced the odds of avoidable hospitalization (odds ratio = 0.995; 95% CI: 0.990–0.999, P = 0.017). Conclusion Greater spatial accessibility to primary care was linked to reductions in ED visits, ED costs, avoidable ED use, and avoidable hospitalization. The E2SFCA method provides a more accurate tool for identifying underserved regions and can inform equitable allocation of healthcare resources. Telemedicine and mobile services should be expanded to address shortages in remote areas.