Some thing work well together
March 11th, 2007 andrewArchetypes – SNOMED-CT – HL7 – GELLO – GLIF
What are the boundaries between these important concepts and where and how do they fit together.
This is an important question, one we have been expending a lot of energy on and we have ended up with some ideas that we would like to share. We also have firm opinions!
Really the problem is that there is overlap, or in some cases “underlap”
HL7 V3 has terminology properties that conflict and create mismatch with SNOMED-CT. Its also very verbose and overloaded by Modelling, complexity and infrastructure issues. HL7 V2 in general does not, as apart from medications it has not really invaded the clinical data relationship space as yet. Its a blank slate with respect to clinical modelling, but quite a well proven and efficient blank slate!
Archetypes as pioneered by OpenEHR has conflict with SNOMED-CT – they try to be terminology neutral and in effect often also invade the Terminology space – as simple terminologies are semantically deficient and need their help. In reality SNOMED-CT relationships and grammar and Archetypes are in the same space and we would view them this way. Ideally the terminology should be able to create the relationships between data items that the archetypes currently create and in many areas SNOMED-CT already does this very well. Our somewhat provocative view is that Archetypes fill the gaps where the terminology is deficient, and with time will gradually fade as the relationships in SNOMED-CT become richer.
Archetypes also conflict with GELLO. Data validation and calculated values should be handled by a constraint language, and GELLO as a direct descendant of OCL fits this bill well. Having a specific “COUNT” node in an archetype should be replaced by some GELLO that can do basic addition.
What about high level decision support? To clinicians this is flow charts. Not dumb ones, but really smart flow charts that already knows whats excluded and whats contraindicated. Not that they can have the final say. Rules are made to be broken and often are for good reasons. GLIF (Guideline Interchange Format) does fit the bill well here – it represents decisions and flow charts very well and is designed to defer to GELLO for the actual computation.
What about the “Big” model – The HL7 V3 model at a high level is quite true to Medical Practice. Medical records really are a collection of observations about a Patient, some right some wrong, some in conflict with each other, that’s the real world.
So where do we see this fitting together now….
HL7 V2 is very efficient and fast and widely implemented. An implementation of the HL7 V3 model over V2 messaging using Archetypes to plaster over the cracks left by SNOMED-CT, complemented by GELLO working on the HL7 V3 Model (represented in the HL7 v2 data) with GLIF for high level decision support. Thats where we see the potential for success and a possibility for some sort of transition from where we are now to a exciting semantically interoperable future.
Is it possible… Its not easy, but it is possible. We have done enough work now to be sure of that.