Using SNOMED CT as a Mediation Terminology: Mapping Issues, Lessons Learned, and Next Steps Toward Achieving Semantic Interoperability

The Clinical Data Repository / Health Data Repository (CHDR) project is a combined effort of the Department of Veterans Affairs (VA) and the Department of Defense (DoD) to exchange clinical information between our Electronic Health Records (EHR). CHDR exchanges standardized, computable data, as opposed to textual data that is only human readable. CHDR utilizes mediation terminologies for health data exchange. For allergy reactions data, CHDR uses SNOMED CT in conformance with Health Information Technology Standardization Panel (HITSP) recommendations. This paper reports how we implemented this solution. Business rules for mapping allergy reactions were established jointly. Each agency independently mapped its legacy data to the same version of SNOMED CT. CHDR has since been implemented in seven locations where VA and DoD have joint patient care environments. Statistics on actual patient data from February-June 2007 showed a 74-99% mediation success rate for allergy reactions data. Examination of mediation failures exposed issues related to mapping and SNOMED CT concept modeling. In addition, we emphasize the significance of adherence to a detailed terminology mediation strategy, desirability of a standard SNOMED CTbased subset for allergy reactions, and the creation of this subset for publication and distribution.