PLACEHOLDER-DRAFT

So what is the role of this metadata in the CRC database?

The ONT database provides a hierarchy of healthcare concepts, and each concept is identified in the ONT database by a unique "path." The concept's path resembles the path of a file in a computer filesystem. Just as directories in a computer filesystem are hierarchical, so the paths of the concepts reflect the hierarchy of healthcare concepts. In the CRC database, all the healthcare concepts (diagnoses, medications, procedures, and measurements) are coded in the patient records using coding schemes like ICD, RxNorm, CPT, and LOINC; the patient data do not include the hierarchical paths from the ONT database. The role of the CONCEPT_DIMENSION table is to map each hierarchical path from the ONT database to its matching code in the CRC patient data. It's this mapping that allows a path from the ONT database to be used in a query on the CRC database; without this mapping, i2b2 would not be able to match ONT concepts with CRC patients.

The CONCEPT_DIMENSION table provides the mapping between all the healthcare concepts (paths) present in an ONT database and the diagnosis, procedure, medication, and measurement codes present in that ONT database's associated CRC patient data. (If a CRC database is associated with more than one ONT database — more than one project — then the CONCEPT_DIMENSION table would need to include the mappings for all the relevant hierarchical paths from all the associated ONT databases for that CRC database.)