The adoption of the regulation establishing the European Health Data Space (EHDS)7 in 2025 marks a turning point for health research. By creating a harmonised framework for accessing and reusing health data across Europe, it promises to stimulate scientific progress. With broader access to reliable and comparable European-level data, the EHDS paves the way for stronger evidence-based public health policies, and greater capacity to anticipate, monitor, and respond to health challenges. Equally, the creation of a European health data space is expected to accelerate innovation in healthcare.
Yet behind the promise of a “single market” for data lies a key question: which data will actually be reusable? Access to poorly documented data is, in practice, no real access at all. One of the EHDS’s core challenges is to ensure that shared data are understandable, reliable, and interoperable.
Data documentation: the first step toward reuse
The secondary use of health data — for research, policy evaluation, or innovation — requires more than simple “access.”
For data to be reused, it must first be clear:
- What data exist: : the nature of the variables, the population covered, the period observed .
- How they were produced : protocols, definitions, collection methods .
- What is their quality : completeness, accuracy, consistency.
- Under what conditions they can be used : legal constraints, available formats, access procedures .
Taking advantage of the EHDS opportunity to structure metadata
The EHDS regulation introduces an obligation for data holders to establish and maintain metadata catalogues — such as FReSH.
These catalogues provide visibility into available datasets in each Member State. This depends, in particular, on interoperability enabled by common metadata standards. They also serve as a bridge between producers and users, built on a shared understanding of what datasets exist and what qualities they hold.
The challenge is to avoid a proliferation of datasets that are theoretically available but practically unusable.
The role of FReSH: documenting for better sharing
In France, FReSH contributes to preparing the integration of national data into the future EHDS.
By cataloguing individual-level data collections through structured metadata records, FReSH makes French data visible within a European framework of interoperability. The catalogue provides standardised information on the origin, quality, and access conditions of datasets.
In doing so, it establishes a trusted foundation, ensuring that the data can be reused safely and effectively.
The EHDS sets the stage for Europe to become a secure space for the circulation of health data. However, this ambition will only succeed if data quality and documentation are placed at the center of priorities.
Documenting data is an investment in their future use: without rich, reliable metadata, access is only an illusion; with them, it becomes a powerful driver of new research.
