Assessing the consistency of a biomedical terminology through lexical knowledge

OBJECTIVE We investigate the use of adjectival modification as a way of assessing the systematic use of linguistic phenomena to represent similar lexical or semantic features in the constituent terms of a vocabulary. METHODS Terms consisting of one or more adjectival modifiers followed by a head noun are selected from disease and procedure terms in SNOMED. Frequently co-occurring adjectival modifiers are systematically combined with the contexts (i.e., terms minus modifier) of each modifier. The existence of these combinations is checked in both SNOMED and the entire UMLS Metathesaurus; the term corresponding to the context alone is similarly checked. Relationships among terms sharing a context and between each of these terms and their context are studied. RESULTS Four pairs of modifiers were studied: (acute, chronic), (unilateral, bilateral), (primary, secondary), and (acquired, congenital). The numbers of contexts studied for each pair ranged from 73 to 974. The percentage of contexts associated with both modifiers ranged from 5 to 50% in SNOMED and from 10 to 60% in UMLS. The presence of the context term varied from 31 to 64% in SNOMED and from 43 to 79% in UMLS. Finally, 172 occurrences (9%) of synonymy between a modified term and the context term were found in SNOMED. One hundred and forty-five such occurrences (8%) were found in the entire Metathesaurus.