Christopher Feahr wrote: >Thomas, >I'm curious to know if your comments are based on a review of SNOMED CT >or of ontology/terminology systems, in general? As you probably know, >SNOMED was designed expressly to support clinical information needs. > yes, but we have to be careful about what needs we are talking about here. SNOMED-CT is a terminology in teh form of a semantic network - i.e. a terminology with an ontological flavour. Its purpose in systems is describing reality, although there are people I have met who do not think rigorous design principles have been applied, and that it is internally inconsistent (one company ran a tool over it and found 12,000 inconsistences). It also has a lot of pre-coordination in it, when what we really need it generative / compositional terminology. But these are details. The main point here is that SNOMED can tell you what the meanings of the parts of a complete blood count test are (and perhaps a good model of blood chemistry in general, e.g. facts like Mean cell volume and Mean cell Hb are attributes of "cell"), but it's not going to provide a model of an actual blood test - as you know, CBCs could have any number of items in them, and this might differ based on lab, health authority or some other factor. This is where archetypes and templates come in - they are about information *in use* not definitions of reality.
Another comparison is the difference between "blood pressure" - a concept you might find described in an ontology, and "blood pressure measurement" - an archetype or template. THe latter is not a model of pressure of fluid in a vessel etc, but a model of the collection of items being measured, the measurement protocol, and any other data about patient state (e.g. sitting etc). So - even if SNOMED was perfect, it doesn't do everything - it is a knowledge support part of the environment, and it can be used to name things and perform inferencing (its main purpose in the eyes of some). - thomas beale - If you have any questions about using this list, please send a message to d.lloyd at openehr.org
