Observational Health Data Sciences and Informatics

The Observational Health Data Sciences and Informatics, or OHDSI (pronounced "Odyssey") is an international collaborative effort aimed at improving health outcomes through large-scale analytics of health data. The OHDSI effort includes diverse researchers and health databases worldwide, with its central coordinating center located at Columbia University.

The group was derived from the Observational Medical Outcomes Partnership (OMOP), a public-private consortium based in the United States of America, created with the goal of improving the state of observational health data for better drug development, which started in response to the U.S. Food and Drug Administration (FDA) Amendments Act of 2007. OMOP developed a Common Data Model (CDM), standardizing the way observational data is represented. After OMOP ended, this standard started being maintained and updated by OHDSI.

As of February 2024, the most recent CDM is at version 6.0, while version 5.4 is the stable version used by most tools in the OMOP ecosystem.