More generic reference model

Bert Verhees bert.verhees at
Fri Sep 2 11:55:47 EDT 2016

On 02-09-16 16:45, Thomas Beale wrote:
> Actually SNOMED did exist when we designed the openEHR RM, and even if 
> today's SNOMED CT had existed we would have done pretty much the same 
> thing I think. The Observation model for example is a structural model 
> of time series data, adapted to direct software use. Trying to use 
> SNOMED to code all that would be painful, and contrary to what SNOMED 
> is for.
Blood pressure is not such a good example. Better examples are concepts 
with much hierarchy or other relationships/attributes connected.

I am not sure what you mean by using SNOMED for coding. Of course SNOMED 
can be used for expression constraints, for example, to create an 
expression which indicates a systolic higher then 165. The expressions 
could be embedded in AQL if it would be ready for that.

Another expression would constrain: Does the patient have a specific 
disease, or one of the twenty diseases which have an "is a" relation 
with that disease, and then with a specific attribute and a specific 
value, etc..
Also for datamining and population care this would be good.

An example is always dangerous, because, the wrong example does not mean 
that the argument is wrong, but the example can become argument of 
discussion. But I try anyway.

Find all patients which had a form of cancer with a specific attribute 
or one of the child forms of that cancer and a specific therapy or one 
of the twenty therapies which are a child-form of that therapy, this is 
maybe not easy to do in OpenEHR right now.

It might be possible that the archetype-structure in which different 
cancers are describes have a different structure for different cancers, 
so it is not on a steady path where you can find characteristics about 
that disease. Same counts for the therapies

And it would be nicer if the query could be embedded in AQL.

So, in my opinion, you need equally formed archetypes for different 
diseases, especially if they are in the same clinical hierarchy, so you 
can find clinical attributes of that disease-hierarchy and terminology 
codes on the same node-Id's and in the same structure.

Maybe a hospital thinks about that when designing archetypes, and is 
doing a good job, but the concept does not enforce this good job.
On the contrary to SNOMED which is well guarded by IHTSDO

OpenEHR could profit from that.

Maybe there are better ideas to integrate SNOMED better in OpenEHR?

best regards

> There are other things we know we would change (AFAIK, all on the PR 
> tracker somewhere), but I can't imagine wanting to throw out basic 
> structures that make developers lives easier.
> - thomas
> On 01/09/2016 01:54, Bert Verhees wrote:
>> Hi,
>> I am just wondering if there are some opinions about this.
>> Do we still need the not so generic reference model which OpenEhr 
>> has, with archetypes denoting Observation, Evaluation etc?
>> Wouldn't a more  generic reference model, like ISO13606 be 
>> sufficient, when the terminology, worldwide, is moving to SNOMED-CT?
>> Because the SNOMED-concepts already indicate in which hierarchy a 
>> data-item belongs (clinical finding, procedure, body structure, etc), 
>> and with much more detail then the OpenEHR reference model.
>> When using SNOMED in OpenEHR there will be redundant information 
>> created, and to not create redundant information is one of the main 
>> golden rules in system design.
>> I think the reference model design needs reconsideration. It comes 
>> from a time when there was no SNOMED-CT.
>> Thanks for any thoughts.
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