UMLS as Knowledge Base-A Rule-Based Expert System Approach to Controlled Medical Vocabulary Management

The National Library of Medicine is developing a Unified Medical Language System (UMLS) which addresses the need for integration of several large, nationally accepted vocabularies. This is important to the clinical information system under development at the Columbia-Presbyterian Medical Center (CPMC). We are using UMLS components as the core of our effort to integrate existing local CPMC vocabularies which are not among the source vocabularies of the UMLS. We are also using the UMLS to build a knowledge base of vocabulary structure and content such that logical rules can be developed to assist in the management of our integrated vocabularies. At present, the UMLS Semantic Network is used to organize terms which describe laboratory procedures. We have developed a set of rules for identifying undesirable conditions in our vocabulary. We have applied these rules to 526 laboratory test terms and have found ten cases (2%) of definite redundancy and sixty-eight cases (13%) of potential redundancy. The rules have also been used to organize the terminology in new ways that facilitate its management. Using the UMLS model as a vocabulary knowledge base allows us to apply an expert system approach to vocabulary integration and management.