LOINC Changes Frustrating Semantic Interoperability in Canada

According to minutes of the 2010-07-29 HL7 Vocabulary Working Group call, the new release of Logical Observation Identifiers, Names, and Codes (LOINC) is creating ambiguity about how to represent things like birth date. Apparently, it is now possible to represent birth date as an "observation", with a value that is a date. This representation conflicts with the "usual" way of representing birth date in the HL7 Clinical Document Architecture (CDA) standard, which represents it as a "demographic attribute of a person".

Really, the fundamental issue here is the failure to recognize that terminologies such as LOINC and SNOMED CT are representations developed in uncoordinated fashion with HL7's CDA, also a representation. Which is to say, that terminologies, information models, and ontologies (obviously) all make ontological commitments.

Conflicting views such as these are common. Indeed the whole TermInfo group of HL7 was created to reconcile conflicting representations (HL7 and SNOMED CT) to ensure (as much as possible) semantic interoperability.