Methods for Exploring the Semantics of the Relationships between Co-occurring UMLS Concepts

Objective: To characterize the relationships among UMLS concepts that co-occur as MeSH descriptors in MEDLINE citations (1990-1999). Design: 18,485 UMLS concepts involved in 7,928,608 directed pairs of co-occurring concepts were studied. For each directed pair of concepts Cl-C2: (i) the “family” of Cl was built, using the UMLS Metathesaurus, and we tested whether or not C2 belonged to Cl's family; (ii) we used the semantic categorization of Metathesaurus concepts through the UMLS Semantic Network and Semantic Groups to represent the semantics of the relationships between Cl and C2. Results: In 6.5% of the directed pairs, the co-occurring concept C2 was found within the “family” of Cl. Detailed results are given. The most frequent co-occurrences involved “Chemicals & Drugs” and “Chemicals & Drugs”, as well as “Disorders” and “Chemicals & Drugs”. Discussion: This work takes advantage of both symbolic and statistical information represented in the UMLS, and analyzes their overlap. Further research is suggested.