Methods Inf Med 2009; 48(02): 178-183
DOI: 10.3414/ME9215
Original Articles
Schattauer GmbH

Definitions and Qualifiers in SNOMED CT

R. Cornet
1   Department of Medical Informatics, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
› Author Affiliations
Further Information

Publication History

18 February 2009

Publication Date:
17 January 2018 (online)

Summary

Objectives: An important feature of SNOMED CT is post-coordination, which is enabled by the SNOMED CT representation specifying whether a relationship is a defining or a qualifier relationship. In this paper the use of qualifier relationships in SNOMED CT is analyzed, as well as the extent to which qualifiers interact with defining relationships, so that pre-coordinated concepts can also be post-coordinated.

Methods: The July 2007 release of SNOMED CT was imported into a database. Analyses were performed by querying this database.

Results: Qualifier relationships occur in 10 out of 61 types of attribute relationships, and it is shown that generally pre-coordinated concepts cannot be constructed by applying post-coordination using qualifier relationships. Most of the qualifier relationships have generic target concepts, making it possible to construct concepts which are not clinically sensible. A logic-based representation is proposed to overcome the drawbacks of the current model.

Conclusions: Defining and qualifier relationships both enable post-coordination in SNOMED CT. Introducing qualifiers for more types of relationships, and using qualifier relationships with more specific target concepts will further improve post-coordination in SNOMED CT.

 
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