Lessons from federated networks for implementing the European health data space. Empirical study.

Objectives: To explore first-hand expert perspectives on the development and use of federated repositories for health data sharing, with a focus on their role in secondary use of health data and the European Health Data Space framework. Methods: A qualitative study was conducted using semi-structured interviews with 19 experts directly involved in developing federated health data repositories. Interview findings were thematically analysed to identify perceived benefits, limitations, and suitable use contexts for federated data-sharing models. Results: Federated networks were perceived as effective in contexts where they can support new opportunities for research data sharing, engage new data providers, and address trust-related barriers. However, participants also identified important limitations. These included high resource demands, complex governance requirements, privacy risks, and reduced suitability for certain types of research. Conclusion: Federated repositories may offer valuable governance and technical solutions for health data sharing, especially where trust and provider engagement are central concerns. Their benefits are context-dependent, and they are not suitable for all research scenarios. The findings contribute to debates on data governance for secondary use and the future role of federated infrastructures under the European Health Data Space.