OHDSI national nodes: helping to strengthen research collaboration across Europe Interview with Renske Los, Erasmus Medical Center, Rotterdam


Renske Los is assistant professor at the department of Medical Informatics, Erasmus Medical Center in Rotterdam, the Netherlands, and co-lead of OHDSI NL. Together with Prof. Peter Rijnbeek she helps onboard new national nodes to the OHDSI Europe chapter.

How do national nodes evolve and why are they important?

Since 2021, national nodes have been set up in Belgium, Germany, Greece, Israel, Italy, Luxembourg, the Netherlands, Portugal, Spain, and the United Kingdom. Last month we onboarded Norway as the eleventh national node in Europe and Finland is currently in the onboarding process. Many nodes have already introduced themselves and their work at the OHDSI Europe symposia, but we’d like to share a little more about what’s going on with these national initiatives.

National nodes are inclusive and open to anyone who wants to join to learn and share experiences with OHDSI-related work. Nodes are comprised of different member groups, ranging from hospitals, research institutes, pharmaceutical and IT companies to SMEs, but are generally led by academic institutions. The format in which the nodes meet varies per country, but many choose a mix between online and F2F meetings, with the annual OHDSI Europe symposia also proving to serve as an ideal locale.

The formation of national nodes was encouraged by the EHDEN consortium to stimulate collaboration using the OMOP Common Data Model (CDM) and OHDSI research and analysis tools and methodologies at a national level within Europe. By meeting nationally, lessons learned and best practices for challenges encountered locally (e.g., mappings from specific EHR systems or national vocabularies), as well as work on studies with a national interest, can be shared.

On a European level, the national nodes can coordinate working together on a larger scale, for example by collaborating in international studies or applying for grants, and keeping oversight on what is going on, which sometimes helps to synergise initiatives. With over 200 organisations currently involved in the national nodes, the European OHDSI network is maturing nicely. To keep up with what’s going on in this growing network, the leads of the national nodes have started meeting quarterly to keep each other informed.


What are some of the challenges the national nodes are facing?

People are generally very enthusiastic about joining the nodes, and a positive vibe can be felt at node meetings. From a personal perspective, it’s very comforting to know that others are dealing with similar challenges, for example, when mapping complex data sets to the OMOP CDM. The node meetings are a great place to learn from each other, as well as for partners to hear what is going on in their country. One challenge many nodes do face, however, is lack of funding, meaning that all work is done on a voluntary basis. Needless to say, this can limit the number of activities that can be undertaken.


What are some of the national nodes currently working on?

Even though the nodes have very similar objectives, the focus areas are currently quite different. While some nodes are organising studies, others focus more on knowledge-sharing and organising educational activities.

  • OHDSI UK is organising a study-a-thon together with the UK Medicines and Healthcare products Regulatory Agency (MHRA) at the end of this month. They will investigate the use of fluoroquinolones in UK primary care and hospital settings and try to characterise rectopexy in the United Kingdom.
  • OHDSI Italia is also working on setting up two initial studies involving several of the data partners who participate in the activities of the node. In addition, they have been working on a template of the Data Protection Impact Assessment related to the harmonisation of the data into OMOP. EHDEN’s November blog is just out and you can find more details about this here!
  • OHDSI Belgium have some great workshops lined up. You can get inspired here with their newsletter.
  • OHDSI Greece have been making many appearances at national conferences and are preparing an online course on quality assurance, as well as hosting an open student day to inform the next generation researchers about OHDSI.
  • In Luxembourg they are looking forward to OHDSI Luxembourg’s inaugural event on December 12th.
  • OHDSI NL is deciding on a first use-case they can work on together and on starting an inventory of all (national) vocabularies that have been mapped to the OMOP CDM.
  • One of OHDSI Germany’s efforts is mapping rare diseases (Orphacodes) to the OMOP CDM, which will surely be of interest to many researchers in the OHDSI community.


Greece national node lead, Pantelis Natsiavas, INAB, at the InnoHealth Forum Innovation Exhibition


Become active in a national node!

If you are working in Europe on OHDSI-related endeavours and are not yet a member of your national node, check out their website ( https://www.ohdsi-europe.org/index.php --> National Nodes) to see how you can become part of your country’s national journey! Can’t find your national node? Then perhaps it’s time to start one! To lead a node, it helps to have some knowledge about the OHDSI community, and the work being done. More details on how to start a node can also be found on the above website.