# OMOP CDM — Observational Medical Outcomes Partnership Common Data Model ## Overview The OMOP Common Data Model (CDM) is the open standard for structuring observational health data, including EHR records, insurance claims, and registries, into a common format that enables federated analytical studies across institutions without sharing raw patient data. It was developed within the OMOP initiative, a public-private partnership involving the FDA, academic institutions, and pharmaceutical companies, and is now maintained by [[OHDSI]]. It supports federated distributed network studies in which each site runs the same analytical code locally and shares only aggregate results. The [[EHDS]] recommends OMOP CDM as the common data format for secondary use across EU Member States. ## Interoperability OMOP CDM and [[HL7 FHIR]] interoperability is being developed through a joint initiative between OHDSI and the HL7 Vulcan Accelerator, with a FHIR-to-OMOP transformation specification under active development as of 2025. OMOP-to-FHIR tooling exists but a fully standardised bidirectional mapping is not yet complete. OMOP CDM also maps to [[CDISC]] SDTM for clinical trial data integration, with conversion guidance maintained by the [[OHDSI Clinical Trials Working Group]]. ## CDM Structure The OMOP CDM organises clinical data into domain tables. Each domain maps source codes to a standard vocabulary: conditions to [[SNOMED CT]], drugs to [[RxNorm]], procedures to [[SNOMED CT]] and [[CCAM]], and measurements to [[LOINC]]. Source codes from [[ICD-10]], [[MedDRA]], and local systems are mapped to OMOP standard concepts via Athena (https://athena.ohdsi.org), which also covers [[ICD-11]], [[MeSH]], [[HPO]], [[MONDO]], [[ORDO]], and NDC. | Domain | Table | Contents | |---|---|---| | **Person** | PERSON | Demographics, one row per patient | | **Observation Period** | OBSERVATION_PERIOD | Periods of clinical data availability | | **Visit** | VISIT_OCCURRENCE | Hospital stays, outpatient visits, ED | | **Condition** | CONDITION_OCCURRENCE | Diagnoses (coded to [[SNOMED CT]]) | | **Drug** | DRUG_EXPOSURE | Prescriptions and administrations (coded to [[RxNorm]]) | | **Procedure** | PROCEDURE_OCCURRENCE | Clinical procedures (coded to [[SNOMED CT]], [[CCAM]]) | | **Measurement** | MEASUREMENT | Lab results and vitals (coded to [[LOINC]]) | | **Observation** | OBSERVATION | Clinical findings not fitting other domains | | **Note** | NOTE | Unstructured clinical notes | | **Death** | DEATH | Date and cause of death | | **Specimen** | SPECIMEN | Biological samples | ## Connections - Maintained by: [[OHDSI]] - Recommended by: [[EHDS]] (OMOP CDM recommended for secondary use across EU Member States) - Vocabularies: [[SNOMED CT]], [[LOINC]], [[ICD-10]], [[ICD-11]], [[MedDRA]], [[CCAM]], [[RxNorm]], [[MeSH]], [[HPO]], [[MONDO]], [[ORDO]] ## Resources - https://hl7vulcan.org/projects/fhir-to-omop/ (HL7 Vulcan FHIR-to-OMOP project) - https://ohdsi.org - https://ohdsi.github.io/CommonDataModel/ (CDM specification) - https://github.com/OHDSI/CommonDataModel (GitHub) - https://athena.ohdsi.org (OMOP vocabulary browser and download) - https://doi.org/10.1093/jamia/ocad247 (Reich et al. 2024, JAMIA, OHDSI vocabularies)