Mapping between SNOMED RT and Clinical terms version 3: a key component of the SNOMED CT development process

SNOMED RT and Clinical Terms Version 3 are two large, controlled medical terminologies that are being merged to form a new work titled SNOMED Clinical Terms (SNOMED CT). One of the first steps in this process was to create maps between semantically equivalent and proximate concepts in the two terminologies. Same-as and is-a relationships were used to map the descriptions from one terminology to concepts in the other terminology. The objectives were to identify semantically equivalent concepts in the two terminologies, to find the most semantically proximate is-a relationships for non-equivalent concepts, and to evaluate the synonymy in the source terminologies. The results suggest that the rate of semantic overlap between descriptions in SNOMED RT and CTV3 is approximately 28%. This article discusses the methodology, issues, and findings of the description mapping process.