Wiki MarkupA core feature of the i2b2 platform is a generic database schema based on the Entity-Attribute-Value concept (EAV) \ [[Nadkarni 1997|http://www.ncbi.nlm.nih.gov/pubmed/9186046]\]. It facilitates the storage of heterogeneous and time-varying biomedical data in a unified and stable data model. In it, a central fact table ("OBSERVATION_FACT") is joined with several dimension tables (e.g. "PATIENT_DIMENSION", "CONCEPT_DIMENSION", ...) in a classic data warehouse star schema:

One advantage of this approach ist that new data elements can simply be added by including definitions in the relevant dimension table(s) (e.g. CONCEPT_DIMENSION) and adding the respective data rows to the fact table. No changes to the database schema itself are required. This generic approach and the resulting simplicity of importing data into i2b2 has contributed to its high uptake in the biomedical community.

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