In a comment on the previous DCM post, Gordon Tomes sent a link to an interesting 2009 academic paper by Scheuermann, Ceusters & Smith - Toward an Ontological Treatment of Disease and Diagnosis [PDF] There is a place for this 'pure', academic approach as a means to seek clarity in definitions, but a telling sentence in the paper for me is: "Thus we do not claim that ‘disease’ as here defined denotes what clinician in every case refer to when they use the term ‘disease’. Rather, our definitions are designed to make clear that such clinical use is often ambiguous."
This is totally right, but despite the apparent ambiguity this clinicians still manage :)
The approach for archetypes/DCMs is not to get tied up in these definitional knots unnecessarily but to concentrate on consensus building around the structure of the data. Use of ontologies and definitions are key elements in designing and modelling archetypes but the resulting models should not be based on academic theory but on existing clinical practice and processes. Our EHRs need to represent what clinicians actually need to do in order to provide care. Sometimes we need to be practical and pragmatic. For example, I once challenged a dissenter to build a Blood Pressure archetype based purely using SNOMED codes - the result was a nonsense, a model that he agreed was not useable by clinicians.
The approach to building the Problem/Diagnosis archetype has not been to try to differentiate these two terms pedantically. Many have tried to separate a 'Problem' from a 'Diagnosis' for years with little success - no point waiting for this to be resolved, it probably won't. And even if we did make a theoretical decision on a definition for each, the clinicians would still likely classify the way they always did, not the way the academics or standards-makers would like them to do it!
In the collaborative CKM reviews for the NEHTA Problem/Diagnosis archetype we have been able to observe that clinicians and other stakeholders have achieved some consensus around the structured data required to represent the concepts of a problem plus the addition of some extra optional data elements to represent formal diagnoses. After completing only four review rounds, the discussion now is focused on finessing the metadata and descriptions, not on debating the structure of the model.
Clinicians may still go round in circles arguing about what constitutes an actual problem vs a diagnosis - for example, some may classify heartburn as a problem, others as diagnosis. No matter. By using a single model to represent both we can ensure that no matter how heartburn may be labelled by any individual clinician, we can easily query and find the data in a health record, and in addition there is a single common model to be referenced by clinical decision support engines.
A small success, maybe.