Policy practice for narrowing urban-rural healthcare gaps: determinants and implementation path of the urban doctors servicing rural areas policy in Beijing, China.

Background: The urban-rural disparities in healthcare resources and service quality remain a critical challenge for equitable public health development in China. To address this, Beijing has implemented the "Urban Doctors Serving Rural Areas (UDSR)" policy-a key counterpart support initiative. Its core goal is to bridge urban-rural healthcare gaps by mobilizing urban medical professionals to serve rural institutions. Methods: Grounded in Van Meter and Van Horn's policy implementation framework, this study employs fuzzy-set Qualitative Comparative Analysis (fsQCA). It examines 39 annual observations from 13 paired urban-rural hospitals in Beijing over 2017-2019. To capture temporal changes, the study applies time-series QCA techniques. It analyzes conditions including support project quantity, subsidy source diversification, prescription rights, professional matching, communication channels, and policy cognition, with rural medical technology improvement as the outcome variable. Results: Three critical determinants of UDSR policy effectiveness are identified: the number of support projects, diversified subsidy sources, and prescription rights for urban doctors in rural institutions. Four implementation pathways are uncovered: (1) goal-and-cognition-driven, (2) professional-matching-driven, (3) external-funding-driven, and (4) comprehensive-factor-driven. Temporal analysis reveals two evolutionary paths: a dominant path achieved via integrating multiple factors, and a transitional path shifting from external funding reliance to professional alignment and goal cognition-reflecting adaptive maturation of the UDSR policy. Conclusion: This study advances understanding of counterpart support policy implementation by revealing synergistic combinations of influencing factors and dynamic evolutionary paths. The findings make two key contributions. Theoretically, they provide insights for policy implementation research in non-western contexts; practically, they offer guidance for optimizing urban-rural healthcare resource allocation and provide a framework for refining targeted support mechanisms in China and similar developing countries.