Lexically-suggested hyponymic relations among medical terms and their representation in the UMLS

Objective: Among the various methods for identifying thesaurus relati ons from text corpora, methods based on head modifier relation are interesting in the context of medical terminologies, especially for those terms which differ from one another by only one modifier. Adjectival modifiers play a particular role because they usually introduce a hyponymic relation. This study focuses on comparing lexically-suggested hyponym ic relations among medical terms to inter-concept relationships represented in the Uni fied Medical Language System (UMLS) Metathesaurus. Methods: Adjectival modifiers were identified from 63,000 medical te rms from the UMLS Metathesaurus, and transformed terms were generated by removing them from the original terms. Candidate hyponymic relations were then tested against inte r-concept relationships recorded in the UMLS Metathesaurus. Results: In 50% of the cases, suggested hyponymic relations were present in the UMLS Metathesaurus. In 25% of the cases, the original term and the tra nsformed terms were “siblings” in the UMLS. In the remaining 25%, no relationship was r ecorded in the UMLS between these two terms. The lack of relationships observed in the UMLS Metathesaurus is disc ussed. Additional methods for automatically assessing the suggested hyponymic relat ions are proposed. Further research directions are briefly presented.