Five Years of the SPHN RDF Journey: FAIR Enough?

Since 2020, the Swiss Personalized Health Network has adopted Semantic Web technologies to standardize health-related data for research in Switzerland. The SPHN Semantic Interoperability Framework promotes semantic interoperability, following the FAIR principles. Within this framework, the SPHN RDF Schema has evolved over five years to define more than 200 concepts across domains such as patient demographics, diagnoses, laboratory results, procedures, omics, and imaging metadata, enabling the representation of structured and machine-interpretable datasets. This study evaluates the evolution of schema versions from 2021 to 2025 and their adoption, examining structural and semantic changes, and analyzing quantitative metadata from projects in the SPHN Metadata Catalog. Results show consistent reuse of core concepts, especially demographics, diagnoses, and laboratory-related concepts, with 67% of SPHN concepts used in projects. The SPHN framework has proven to be a viable national standard for FAIR health data representation. Nonetheless, semantic modeling alone does not guarantee full interoperability. Future efforts must enhance data structuring and quality at the source, promote RDF adoption in research workflows, and develop user-friendly tools for querying and visualizing data.