The Observational Health Data Sciences and Informatics (or OHDSI, pronounced "Odyssey") network is a multi-stakeholder, interdisciplinary collaborative to bring out the value of health data through large-scale analytics. OHDSI aims to generate accurate, reproducible, and well-calibrated evidence and promote better health decisions and better care.

OHDSI Europe is led by the coordinating center embedded in the Health Data Science Group of the Erasmus University Medical Center in Rotterdam, The Netherlands. We like to build a strong European OHDSI community that actively contributes to the further extension of the OMOP-CDM and analytical tool development.

EHDEN was launched in November 2018 to address the current challenges in generating insights and evidence from real-world clinical data at scale, to support patients, clinicians, payers, regulators, governments, and the industry in understanding wellbeing, disease, treatments, outcomes and new therapeutics and devices. The OMOP Common Data Model is at the heart of EHDEN. The EHDEN project established a broad ecosystem of more than 160 data partners and 60 certified SMEs across 29 countries, enabling large-scale, privacy-preserving research through a common framework. EHDEN has accelerated real-world evidence generation for regulators, academia, and industry, establishing Europe as a global leader in federated health data science and infrastructure.

The Data Analysis and Real World Interrogation Network (DARWIN EU®) is the coordination centre established by The European Medicines Agency (EMA) and the European Medicines Regulatory Network to provide timely and reliable evidence on the use, safety and effectiveness of medicines for human use, including vaccines, from real world healthcare databases across the European Union (EU). DARWIN EU® has created a permanent federated network of real-world health data standardized to the OMOP Common Data Model. It has onboarded dozens of European data partners and already delivered studies supporting regulatory decisions on drug safety, effectiveness, and disease epidemiology. DARWIN EU® has demonstrated the feasibility of rapid, large-scale, cross-country analyses, strengthening the evidence base for EU health regulators and public health policy. In DARWIN EU’s most recent report from early 2025 you can find these results: - DARWIN EU® expanded to 30 data partners, with access to data from around 180 million patients from 16 European countries - 59 studies were conducted representing a 47.5% increase year-over-year - The proportion of feasible studies addressing initial requests increased from 60% to 78% year-over-year - The median study duration from DARWIN EU® studies is now 4 months from protocol approval to study results