A core part of the iCARE4CVD project is connecting health information from a vast amount of heart-related studies across Europe through a federated database. By creating this large and diverse source of knowledge, the project aims to speed up cardiovascular research and improve how heart disease is prevented, diagnosed, and treated—supporting more personalised care for patients.
But before advanced computer tools or artificial intelligence can be used, researchers face a more basic challenge: making sense of the data itself. What information is available? How was it collected? And can results from different studies be meaningfully compared and used together?
This essential groundwork is led by Komal Gilani (Maastricht University) and her WP2 team, working closely with Marlo Verket (Aachen University) and the wider WP1 team.
Together, they organise and harmonise information from the studies included in iCARE4CVD—without ever accessing individual patient records—so the data can be used more effectively to advance cardiovascular research.
In this article, we explain the team’s latest milestone: the development of the Clinical Metadata Exploration Ontology (CMEO).
The challenge of fragmented heart disease data
Across Europe, many studies collect valuable information about heart disease. Patients generously contribute their data to help improve care. However, these studies are often carried out independently and describe their data in different ways.
For example, studies may:
- Use different names for the same condition, such as recording a heart attack as “previous heart attack” in one study and “myocardial infarction” in another
- Measure the same information in different ways, such as blood pressure taken at different times or reported in different units
- Follow different rules about who can access or reuse the data
Because researchers cannot freely inspect individual patient records, it can be difficult to know which studies are relevant, whether data can be combined, or whether reuse is allowed. As a result, important questions about heart disease may take longer to answer—even when the data already exist.
CMEO: A new way to organise and compare heart disease studies
The iCARE4CVD team is addressing this challenge step by step.
First, WP2 introduced the CDE-Mapper, a tool that helps standardise how individual data points—such as blood pressure, medication use, or lab results—are described. This allows different studies to “speak the same language” when referring to similar information.
Building on this work, the team developed the Clinical Metadata Exploration Ontology (CMEO). CMEO is a new way to organise information about cardiovascular studies (and more), making it easier to find, compare, and reuse data.
Rather than focusing on patient data, CMEO focuses on metadata—information about the studies themselves, including:
- What each study is about
- What types of data were collected
- How measurements were taken
- Under what conditions the data can be reused
This allows researchers to understand and compare studies without accessing personal health records, while making better use of the data that already exist.
How does CMEO work?
What makes CMEO different from existing tools is that it works with information about studies (metadata), not with patient data. It helps researchers understand how studies were designed, what was measured, and under which conditions data can be reused—without looking at individual health records.
By linking study descriptions to shared medical definitions, CMEO makes it easier to see when different studies are talking about the same things, even if they use different names or formats. This helps researchers compare studies and decide which ones are suitable for a specific research question, while protecting patient privacy.
Until now, this information was often scattered across different documents or systems. CMEO fills this gap by bringing study details, data descriptions, and reuse rules together in one place, making it easier to understand how studies can be compared or reused.
Importantly, although CMEO was developed within the iCARE4CVD project, it is not limited to heart disease research.The same approach can be used for many types of health studies, as long as basic information about the study and its measurements is available.
Why this matters?
Health data shared by patients has enormous potential to improve care—but only if it can be clearly understood and responsibly used.
By making studies easier to find, understand, and compare, CMEO helps researchers spend less time navigating data and more time answering important questions about heart disease. It supports collaboration across countries and studies, helping research move forward more efficiently.
What’s important, CMEO works with information about studies, not with patient data itself. Researchers still need expert judgement to decide whether studies can be combined, and the approach depends on how clearly studies describe their data. These limits are intentional and help ensure that research is carried out responsibly and in line with data-protection rules.
Together, this work brings us one step closer to turning Europe’s fragmented cardiovascular data into a connected source of knowledge—one that can deliver real benefits for patients.
