New Platform Makes European Health Data Findable, Accessible and Reusable

Every year, hospitals and research institutes across Europe generate staggering volumes of observational health data: electronic health records, claims databases, registry entries and clinical measurements collected during routine care. Yet much of this information remains locked away in incompatible formats, undocumented systems and institution-specific databases that researchers cannot easily discover, let alone analyze. A team at the University of Aveiro in Portugal has now presented a practical answer to this long-standing problem. In a study published in Multimedia Tools and Applications, João Rafael Almeida, Jorge Miguel Silva and José Luís Oliveira describe the EHDEN Catalogue, a web-based platform designed to help data custodians and researchers manage, standardize and analyze health data in line with the FAIR principles, the widely adopted guidelines holding that data should be findable, accessible, interoperable and reusable.

The FAIR principles, first articulated in a landmark 2016 paper in Scientific Data, were conceived as a response to a paradox of modern science: the sheer abundance of data coexisting with an inability to put it to work. The principles do not mandate that data be open, but rather that it be described in ways that machines and humans can act upon. In biomedicine, however, turning FAIR into reality has proved notoriously difficult. Hospital datasets are governed by privacy law, stored in legacy systems, and annotated with local coding conventions that resist harmonization. Previous studies, including work by the European Commission expert group on FAIR data and analyses of hospital data during the COVID-19 pandemic, have documented how even well-resourced institutions struggle to make medical datasets genuinely interoperable.

The EHDEN Catalogue emerged from the European Health Data and Evidence Network, a project funded through the Innovative Medicines Initiative 2 Joint Undertaking under grant agreement No 806968. EHDEN’s ambition is to create a federated network of European data partners whose databases share a common analytical language. That language is the OMOP Common Data Model, or CDM, developed by the Observational Health Data Sciences and Informatics community. The OMOP CDM defines a standardized set of tables and relationships for observational health data, so that a prescription record in Lisbon is structured the same way as one in Leiden or Barcelona. Once data are mapped into this model, the same analysis code can run across many institutions, enabling large-scale studies of drug safety, disease outcomes and treatment patterns without moving patient-level records across borders.

Technically, the EHDEN Catalogue is a web application that guides data custodians through the process of profiling and documenting their databases. Institutions register their data sources, describe their provenance and content, and run standardized characterization scripts that extract summary statistics about the underlying OMOP CDM implementation. These summaries, covering everything from vocabulary coverage to the distribution of patient counts and observation periods, are aggregated into machine-readable profiles. The platform builds on established web standards, including the W3C’s Data Catalog vocabulary, which provides a semantic framework for describing datasets, their publishers, licenses and access conditions. The result is a catalogue that is not merely a list of databases but a structured, queryable map of the European observational data landscape.

Each letter of the FAIR acronym maps onto a concrete design decision in the platform. Findability is served by rich metadata and persistent identifiers that make data sources discoverable through search. Accessibility is addressed through clearly documented access procedures rather than unrestricted downloads, respecting the governance constraints that necessarily surround patient data. Interoperability flows from the OMOP CDM itself, which gives heterogeneous hospital systems a shared schema, and from the catalogue’s use of standard vocabularies. Reusability is supported by detailed data quality assessments and characterization reports that tell prospective researchers exactly what a database contains, how complete it is, and whether it suits a given study. The authors emphasize that this combination transforms the platform into a comprehensive solution, offering data custodians and researchers a suite of tools and services rather than a single static registry.

The platform also incorporates analytical capabilities that extend beyond documentation. By connecting to visualization and exploration tools, including the Apache Superset business intelligence framework, the catalogue allows users to interrogate aggregated database profiles and compare institutions before committing to a collaboration. This matters because choosing the right data source is one of the most consequential decisions in observational research. A study of a rare adverse drug reaction, for example, requires databases with sufficient patient numbers, adequate follow-up time and reliable recording of the relevant exposures. The catalogue’s profiling reports make such feasibility assessments possible at a distance, reducing the trial-and-error that has historically characterized multi-database studies.

The work builds on a lineage of earlier systems developed by the same group. The EMIF Catalogue, described in 2019 in the International Journal of Medical Informatics, was a collaborative platform for sharing and reusing biomedical data across European medical informatics projects. Subsequent contributions refined the approach: a methodology for cohort harmonization in multicentre clinical research, a secure architecture for exploring patient-level databases distributed across institutions, and more recently a web platform called MONTRA2 for profiling distributed health databases, along with chatbot-like tools to enhance the discovery of OMOP CDM databases. The EHDEN Catalogue consolidates these threads into a production-grade application deployed across the EHDEN network, which has grown to encompass dozens of European data partners mapping billions of patient records to the common data model.

The timing of this work is significant. The European Health Data Space, a legislative initiative currently reshaping health data governance across the European Union, aims to establish a single market framework for the secondary use of health data. Workshops at the European Journal of Public Health have debated whether Europe is ready to maximize the reuse of health data under this framework, and pilot infrastructures for cross-border data exchange are already being tested. Platforms like the EHDEN Catalogue supply a crucial piece of the puzzle: the technical scaffolding that makes data discoverable and interoperable at a continental scale. Without such infrastructure, legal frameworks alone cannot deliver the promised research benefits, because researchers would still face the practical impossibility of locating and assessing suitable data sources.

The study’s authors report that the EHDEN Catalogue significantly improves the visibility, searchability and reusability of biomedical data across Europe, paving the way for more effective and efficient healthcare research with potential impact on the broader European healthcare landscape. The work received funding from the EU/EFPIA Innovative Medicines Initiative 2 Joint Undertaking, and Silva was supported by the European Commission under grant agreement 101081813 for the Genomic Data Infrastructure project. The authors declare no conflicts of interest, and the research involved no direct handling of patient data, which is consistent with the platform’s federated philosophy: aggregated metadata and characterization summaries travel, while patient-level records stay behind institutional firewalls.

For the wider scientific community, the message is that FAIR compliance is achievable in health data when it is engineered into workflows rather than bolted on afterward. The EHDEN Catalogue demonstrates that a carefully designed application, grounded in a common data model and open metadata standards, can convert fragmented national databases into a coherent research resource. As observational studies increasingly inform regulatory decisions, drug safety surveillance and health technology assessment, the ability to find, evaluate and reuse real-world data will only grow in importance. The Portuguese team’s platform offers a template for how that transformation can happen, one documented, standardized and searchable database at a time.

Subject of Research: FAIR-compliant sharing and management of observational health data through the EHDEN Catalogue platform

Article Title: Sharing observational health data following FAIR principles

Article References: Sharing observational health data following FAIR principles. (n.d.). https://doi.org/10.1007/s11042-026-21974-4

Image Credits: AI Generated

DOI: 10.1007/s11042-026-21974-4

Keywords: FAIR principles, observational health data, EHDEN Catalogue, OMOP Common Data Model, data sharing, data interoperability, health informatics, biomedical data discovery, European Health Data Space, data standardization, electronic health records, University of Aveiro