Multi-layered Knowledge Representations for Healthcare (was RE: An argument for bridging information models and ontologies at the syntactic level)

Dan and Peter,
 
Based on conversations on this topic, there appears to be consensus of the need
for multi-layered knowledge representation schemes
for heatlhcare.  Will be great if we could brainstorm and come to some sort of
consensus on these "layers". Would like to propose a
strawman as enumerated below.
 
Layer 0 = Entity - Attribute - Value or RDF triple based rerpesentations.
Layer 1 = MetaClasses, e.g., Observation as in HL7/RIM
Layer 2 = Classes in a Patient Model, Document Models, etc, e.g., the class of
HbA1c results for a class of Patients.
Layer 3 = Data that are instances of Classes, e.g., a particular HbA1c result
for a patient John...
 
As per your e-mail, you seem to be suggesting that there is something in between
Layer 1 and Layer 2. However, please note that Layer 2 consists
of classes of assertions in the patient record and not instances.
 
More reespnses are embedded in the e-mail below.
 
<dan> With apologies to Peter in case I misrepresented your SOA
presentation...Last week, Peter Elkin of Mayo Clinic delivered a presentation
where he called the HL7 RIM a "first order ontology" because of the abstraction
level of the RIM. He called the models derived from the RIM, e.g. analytic
models, patient care document models like CDA, etc, "second order ontology"
because they add a layer of concreteness to the abstractions of the RIM, i.e. an
object with classCode of observation and moodCode of order becomes an
"observation order object" with neither a classCode nor a moodCode. 
 
[VK] Are there mathematical ways of describing these "derivations" for e.g., by
using operations such as instantiations and generalizations/specializations.
 
Also, in the above, it's not clear what the semantics of an "observation order"
object is?
For e.g., observations and orders are semantically distinct concepts, so in some
sense an observation order class is likely to be unsatisfiable?
 
The semantics of "moodCode" is not clear in Knowledge Representation terms. For
instance, do various mood codes partition the instances of a class
into subclasses that are possbily mutually disjoint?
 
 Finally, the coding systems themselves support the concreteness of a "third
order ontology." For example, the SNOMED concept becomes an object itself
without a code attribute, moodCode attribute, or classCode attribute, e.g. a WBC
order. />
[VK] One way of looking at a Snomed code is that it defines a class (e.g., blood
pressure) of all the instances of blood pressure readings which would imply that
it belongs to Layer 2 as defined above? 

			<dan> see above for the "first order to third order
model." Your metaclass looks like Peter's "first order ontology." However, your
"instances" get introduced too early...your "instances" point to actual medical
record assertions, and Peter's model suggests that there is more "in between."
In Peter's model, the actual medical record assertion would be an instance of
his "third order ontology." />
			
			[VK] Agree. As per the layering introduced above,  Layer
2 would correspond to classes of assetions and Layer 3 would correspond to
actual instances or assertions.
			
			 <dan> I completely agree that the HL7 RIM is one level
more "concrete" than the earlier EAV models. The EAV model represents the
ultimate in abstraction, similar to RDF triples. Perhaps Peter would be more
correct to say that EAV is a "first order ontology" and that the HL7 RIM is a
"second order ontology." />
			 
			[VK]  Agree: As per layering introduced abiove,  The
EAV/RDF triples layer could be layer 0, and the HL7/RIM layer could be layer 1

			 
			Look forward to further brainstorming and feedback on
this.
			 
			Cheers,
			 
			---Vipul


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