Representing the Umls as an Oodb: Modeling Issues and Advantages Design: an Object-oriented Database Representation Is Utilized to Represent the Two Major

Objective: The Uniied Medical Language System (UMLS) designed by NLM combines many well established authoritative medical informatics terminologies in one knowledge representation system. Such a resource is very valuable to the healthcare community and industry. However, the UMLS is very large and complex and poses serious comprehension problems for users and maintenance personnel. We present a representation to support the comprehension and navigation of the UMLS. components of the UMLS, the Metathesaurus and the Semantic Network, as a uniied system. The semantic types of the Semantic Network are modeled as semantic type classes. Intersection classes are deened to model concepts of multiple semantic types which are removed from the semantic type classes. Results: We present examples of how the intersection classes help expose omissions of concepts , highlight errors of semantic type classiication, and uncover ambiguities of concepts in the UMLS. The resulting UMLS OODB schema is deeper and more reened than the Semantic Network since intersection classes are introduced. The Metathesaurus is classiied into a larger number of mutually exclusive, uniform sets of concepts. The schema improves the comprehension and navigation of the Metathesaurus. Conclusions: The UMLS OODB schema supports the comprehension and navigation of the Metathesaurus. It also supports exposing and resolving modeling problems in the UMLS.