Link between goals and other clinical concepts

Thomas Beale thomas.beale at
Thu Jun 26 05:40:11 EDT 2014

Hi Diego,

On 26/06/2014 09:16, Diego Boscá wrote:
> Well, I would say that deciding what's in and what's out of the
> reference model can be tricky sometimes. If we assume that clinical
> knowledge evolves (one of the basis of dual model approach) isn't safe
> to say that the less clinical knowledge we put in the reference model
> the better?

the problem with this dictum is that it doesn't work as an Occam's 
razor, which is what you need - i.e. objective criteria for making the 

The criterion I developed in 2000 or so, to determine what should be in 
an RM underpinning archetypes was:

  * the RM should include only domain-invariant semantics i.e. semantics
    that are widely agreed to be the same across all parts of the chosen

So for example, we (probably) all agree that a type like DV_QUANTITY / 
Quantity / PQ  should be in the reference model, with the ability to 
represent at least a Real value + units - because it's a standard 
concept across the whole health data domain.

Do we agree that an EHR 'Entry' is a domain-invariant concept for the 
domain of say EHRs? It seems to be the case, even if less easily 
definable what one is, since you find something like it in all EHR 
models I have seen (including proprietary ones). Are the openEHR 
concepts Observation, Evaluation, Instruction, Action, AdminEntry domain 
invariant in the EHR space? I think it can be argued that these concepts 
are standard not only in medicine but in engineering in general (where 
the concept of 'maintenance' of systems appears).

People involved in building 13606 (I was one of them) on the other hand 
will differ. That's because what 13606 s trying to do is different - 
it's not trying to be a model of something based on principle, it's 
trying to be a model of a consensus view of how heterogeneous health 
data could be converted into a neutral format for sharing, without 
losing original semantics.

Anyway, in the years since the first archetypes, other people have 
thought up the 'reference archetype' notion, and ADL /AOM have been 
greatly improved, in ways that would support that concept. I think we 
are still working out where this ends. Maybe a modern version of the 
criterion above will be fractally spread out over layers of RM / 
archetypes, in a new future where every layer is some kind of 
programming language whose artefacts act as inputs into the virtual 
machine represented by the layers below.

It will be very interesting to see if new/better principles emerge to 
say what should go in (or not) to the RM. But one thing I know is: the 
terms 'less', 'more', 'too much' etc are not useful.

- thomas

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