Tuesday, July 14, 2009

hoot72: An Ontology for HL7 v. 2.3

hoot72 is an interesting experiment by CDC to create an OWL ontology to capture in a coherent fashion the major entities recognized in HL7 v. 2.3.

The ontology is associated with a blog, which draws attention to some of the unfortunate consequences which flow from the fact that HL7 is flexible in the familiar ways (thus it allows the NK code for next of kin to be used also, for example, for nurses).

The OWL framework provides a clear perspective on HL7 v. 2.3, and avoids the usual problems (with act, observation, etc.) which plague v.3.

2 comments:

Grahame Grieve said...

> thus it allows the NK code for next of kin to be used also, for example, for nurses

well, I guess I'm going to comment again. It's a field that users can put what they need into. So it actually allows you to insert a treatise about the stupidity of the world in general, or perhaps about selected SDOs if that's too your liking, instead of some next of kin code. That clearly wouldn't be "conformant". The question is, for any particular use, is that use consistent with the definition of the field?

I don't think it is in the hoot example. But consulting the standard, the definition is loose - *like the definition of next of kin in the real world*.

Of course, in a competition to find the worst case of egragarious mis-use of a standard, HL7 regulars would line up to bring forward their favorite cases. But HL7 is not alone here. HTTP is the same too. As for web services....

What this does betray is a flaw in the whole picture: the standards body defines a logical structure, but business use cases require things to be done, and how are they going to be done? So some partially educated analyst makes a (variably) bad decision under considerable pressure, usually with some input from actual implementers. The outcomes are unpredictable.

Actually tightening the definitions (like in a proper ontology) can make things worse, and so can loosening them. Though either can make things better for at least some users in some circumstances.

It's just something we have to live with.

hoot said...

Barry. Thx for the post.

The comment above - "standards body defines a logical structure" + "business use cases require things to be done" + "actual implementers" => "outcomes are unpredictable" - sums up the structural obstacle to interoperability.

A move into semi-structured graphs is meant to reflect this. Now, would these have enough structure to be useful? I think so. Yes they reflect many ways to represent the "same thing" - the same issue BTW with medical codes - but post mapping analysis should expose these equivalences.

BTW, the ontology now on the hoot72 site is too rigid (it looks like an Object Model!) but that will change with the next revision (early next week).

Finally, "in a competition to find the worst case of egragarious mis-use of a standard, HL7 regulars would line up to bring forward their favorite cases" - that would be nice. There are too many academic niceties out there! What about a real-world showcase? Anybody?