How Ontologies Can Improve Semantic Interoperability in Health Care

The main rationale of biomedical terminologies and formalized clinical information models is to provide semantic standards to improve the exchange of meaningful clinical information. Whereas terminologies should express context-independent meanings of domain terms, information models are built to represent the situational and epistemic contexts in which domain terms are used. In practice, semantic interoperability is encumbered by a plurality of different encodings of the same piece of clinical information. The same meaning can be represented by single codes in different terminologies, pre- and postcoordinated expressions in the same terminology, as well as by different combinations of (partly overlapping) terminologies and information models. Formal ontologies can support the automatically recognition and processing of such heterogeneous but isosemantic expressions. In the SemanticHealthNet Network of Excellence a semantic framework is being built which addresses the goal of semantic interoperability by proposing a generalized methodology of transforming existing resources into "semantically enhanced" ones. The semantic enhancements consist in annotations as OWL axioms which commit to an upper-level ontology that provides categories, relations, and constraints for both domain entities and informational entities. Prospects and the challenges of this approach — particularly human and computational limitations — are discussed.