Representing the UMLS as an Object-oriented Database: Modeling Issues and Advantages
- Affiliations of the authors: University of Medicine and Dentristry of New Jersey, Newark, New Jersey (HG); New Jersey Institute of Technology, Newark (YP, JG, L-mL); Kean University, Union, New Jersey (MH); Columbia University, New York, New York (JJC)
- Correspondence and reprints: Huanying Gu, PhD, Department of Health Informatics, UMDNJ School of Health-related Professions, 65 Bergen Street, Newark, NJ 07107-3001. e-mail: 〈guhy{at}umdnj.edu〉
- Received 3 March 1999
- Accepted 20 September 1999
Abstract
Objective The Unified Medical Language System (UMLS) combines many well-established authoritative medical informatics terminologies in one knowledge representation system. Such a resource is very valuable to the health care community and industry. However, the UMLS is very large and complex and poses serious comprehension problems for users and maintenance personnel. The authors present a representation to support the user's comprehension and navigation of the UMLS.
Design An object-oriented database (OODB) representation is used to represent the two major components of the UMLS—the Metathesaurus and the Semantic Network—as a unified system. The semantic types of the Semantic Network are modeled as semantic type classes. Intersection classes are defined to model concepts of multiple semantic types, which are removed from the semantic type classes.
Results The authors provide examples of how the intersection classes help expose omissions of concepts, highlight errors of semantic type classification, and uncover ambiguities of concepts in the UMLS. The resulting UMLS OODB schema is deeper and more refined than the Semantic Network, since intersection classes are introduced. The Metathesaurus is classified into more mutually exclusive, uniform sets of concepts. The schema improves the user's comprehension and navigation of the Metathesaurus.
Conclusions The UMLS OODB schema supports the user's comprehension and navigation of the Metathesaurus. It also helps expose and resolve modeling problems in the UMLS.
Footnotes
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This work was supported in part by a cooperative agreement (HIIT contract 70NANB5H1011) between the National Institute of Standards and Technology Advanced Technology Program and the Healthcare Open Systems and Trials, Inc. consortium.
