Overview: The foundation of reliable observational science starts with speaking a common language. OHDSI maintains and evolves standards that transform disparate electronic health record (EHR) and administrative claims databases across institutions, languages, and coding systems into a single harmonized structure.

Value to OHDSI: Without standardized data, federated research is impossible. Harmonization allows analytic code developed at one institution to run seamlessly across hundreds of partner databases globally without sharing sensitive patient-level data.

Key Resources:

• OMOP Common Data Model (CDM): Specifications, entity-relationship diagrams, and documentation.
• Standardized Vocabularies & ATHENA: Comprehensive ontology search engine mapping SNOMED, RxNorm, LOINC, ICD, and more.
• Data Quality Tools: DataQualityDashboard (DQD) and Achilles.
• THEMIS Working Group: Best practices and conventions for Extract, Transform, Load (ETL) implementations.

What OHDSI Has Done:

• Harmonized health data representing nearly a billion patient records across more than 50 countries.
• Built ATHENA, mapping millions of international medical concepts into unified standard domains.
• Established global benchmark data quality frameworks now adopted by international regulatory agencies, academic medical centers, and national health initiatives.