Dutch hospitals show what health data standardisation really takes

Five Dutch hospitals have demonstrated how laboratory data can be standardised and exchanged using international terminology and interoperability standards, producing measurable improvements in data quality and making millions of laboratory results available for reuse. The results provide a practical example of the work healthcare systems will need to undertake as Europe moves towards wider health data exchange through the European Health Data Space (EHDS).

The REUSE-LAB project standardised laboratory information using LOINC, SNOMED CT and UCUM. In two participating hospitals, the resulting data were subsequently exchanged through HL7 FHIR with the national intensive-care registry operated by Stichting NICE. Across the project, an average of 91% of laboratory parameters could be standardised directly, while data delivery became 25% more accurate and 39% more complete.

The result was more than 8.9 million laboratory results per year becoming consistently available for reuse. The project also exposed an important reality behind interoperability: exchanging healthcare data reliably requires considerable work at the source before connecting systems through an API or national infrastructure can deliver its full value.

Standardisation starts inside the hospital

Laboratory data are particularly important because they contribute to a large proportion of clinical decisions, yet hospitals have historically developed their own names, codes and registration practices. Two laboratory systems may therefore measure essentially the same clinical parameter while describing or structuring it differently.

That variation becomes a significant problem when information is reused outside the organisation that created it. A clinician may be able to understand a local description, but a quality registry, research environment, regional data platform or algorithm needs information that can be interpreted consistently and automatically. Technical connectivity alone cannot resolve differences in meaning.

REUSE-LAB therefore addressed several layers simultaneously. LOINC was used to identify laboratory observations, SNOMED CT supported clinical terminology and UCUM standardised units of measurement. HL7 FHIR subsequently provided the technical mechanism through which standardised information could be exchanged.

The project found that this process did more than prepare data for external exchange. Standardisation uncovered duplicated codes, unclear descriptions and missing metadata within source systems themselves. Correcting those problems improved the quality of the underlying information, illustrating why interoperability and data quality cannot be treated as separate challenges.

Millions of results become reusable

The scale of the results makes the project particularly relevant. According to the Dutch Society for Clinical Chemistry and Laboratory Medicine (NVKC), 91% of laboratory parameters could on average be directly standardised. Data delivery accuracy improved by 25% and completeness by 39%, resulting in more than 8.9 million results becoming unambiguously available for reuse each year.

A structured standardisation process supported by technology from Medscio reduced the error rate to almost zero and was estimated to make the process around twelve times faster than manual approaches. Those figures matter because large-scale interoperability cannot depend indefinitely on specialists manually translating local codes whenever data need to move between systems.

Five hospitals participated: Amsterdam UMC, Elisabeth-TweeSteden Ziekenhuis, Noordwest Ziekenhuisgroep, Franciscus Gasthuis & Vlietland and Radboudumc. The project also involved Stichting NICE, professional laboratory organisations and terminology specialists. An expansion programme is now being prepared to allow more hospitals and laboratories to adopt a structured standardisation process.

That next step will be crucial. A successful pilot proves technical and organisational feasibility, but the larger challenge is making the approach repeatable across institutions with different laboratory systems, historical coding practices and data-governance arrangements.

EHDS depends on work that users rarely see

The European Health Data Space is creating a framework for making health information more accessible for care, research, innovation and policymaking across Europe. Much of the discussion around EHDS understandably concentrates on legislation, infrastructure and patients' ability to access and share information. Yet the usefulness of that infrastructure will ultimately depend on the quality and consistency of the data flowing through it.

REUSE-LAB demonstrates the less visible layer underneath that ambition. Before laboratory information can be reliably reused across organisations, local terminology has to be mapped, metadata corrected, units standardised and semantic differences resolved. Only then can interoperability standards such as FHIR transport information without losing its meaning.

The project also illustrates why the principle of standardising data once for multiple uses is attractive. The same high-quality laboratory information can potentially support direct patient care, quality registries, research, regional data platforms and future AI applications rather than being repeatedly transformed for each individual purpose.

That approach aligns with wider Dutch programmes such as CumuluZ and with the objectives of EHDS. But the Dutch results also provide a useful warning for Europe: creating rules for health data exchange is easier than harmonising decades of information accumulated across thousands of healthcare organisations.

Interoperability therefore should not be measured simply by whether systems can connect. The more meaningful test is whether information arriving at the other end retains enough consistent clinical meaning to be trusted and reused. REUSE-LAB shows that achieving that is possible, but also why much of the hardest work happens long before anyone presses 'send'.