Archetypically Stupid!

Recently (December 1, 2006) the Health Informatics Technical Committee of the International Standards Organisation (ISO) released a draft Standard entitled Health informatics — Electronic health record communication — Part 2: Part 2: Archetype interchange specification. The closing date for comments is in March, 2007.

The draft document is on its way through the various ISO and CEN processes towards being approved as one of the five parts of the TC 215 Standard on Electronic Record Communication. (pr13606).

Overall the Standard – if approved - aims to define how extracts of patient records can be safely and reliably moved between two EHR systems which are compliant with the Standard once approved.

Key to the success of the approach being adopted is the use of an information construct called an Archetype which defines how clinical content within the record is to be laid out and interpreted.

Without going into too much detail an example of how the Archetype is intended to be used can be better understood as follows.

Assume we wish to place a patient’s blood pressure into an Electronic Health Record (EHR).

In the context of a defined and identified individual patient, an identified healthcare provider (the observer) and the date and time of the observation, it is possible to use an Archetype which has the concept name of ‘blood pressure’. This permits recording of the systolic and diastolic blood pressure values along with associated information (e.g. is this blood pressure part of an assessment for postural hypotension where body position is important or is this blood pressure measured with a described cuff size, etc). Given the detail that may be needed to handle electronic measurements, continuous or 24 hour measurements and so on, the possible complexity becomes obvious if a single archetype is required to handle the concept of ‘blood pressure’. (I guess the response from proponents of Archetypes would most likely be that this would be handled by higher level assemblages of Archetypes, but clearly the downside of this approach is the ultimate number of Archetypes needed).

All the actual data entered is intended to be stored, along with the patient and Archetype identifying information, in an EHR system that can access, when requested, the Archetype ‘framework’ into which the recorded values have been placed. This allows the re-creation of the ‘whole’ of the observation, as needed, in any compliant system. An individual patient record can of course be made up of many data elements (described and constrained by many different Archetypes) to build up a fuller and more complex EHR record.

The benefit claimed for this approach is that any computer system which can locate and ‘interpret’ the correct Archetype can accurately re-present and re-use the EHR information (i.e. provide semantic interoperability between EHR systems). The importance of finding the correct Archetype to utilise becomes obvious here as using a different version of an Archetype, or the wrong Archetype, could be very problematic. This has a range of obvious consequences around the need for effective naming and version control conventions.

Why am I bothering to comment on this somewhat obscure standards balloting event?

The answer is that I simply do not believe use of Archetypes is ready for ‘prime-time’, especially as a global standard, until a vast amount more work is done.

My specific concerns are as follows:

1. The draft standard admits it is unclear how many Archetypes are needed for a successful general purpose EHR and the amount of work needed to create them.

To quote:

Archetype Repositories

“The range of archetypes required within a shared EHR community will depend upon its range of clinical activities. The total set needed on a national basis is presently unknown, but there might eventually be several thousand archetypes globally. The ideal sources of knowledge for developing such archetype definitions will be clinical guidelines, care pathways, scientific publications and other embodiments of best practice. However, “de facto” sources of agreed clinical data structures might also include:

• the data schemata (models) of existing clinical systems;
• the lay-out of computer screen forms used by these systems for data entry and for the display of analyses performed;
• data-entry templates, pop-up lists and look-up tables used by these systems;
• shared-care data sets, messages and reports used locally and nationally;
• the structure of forms used for the documentation of clinical consultations or summaries within paper records;
• health information used in secondary data collections;
• the pre-coordinated terms in terminology systems.

Despite this list of de facto ways in which clinical data structures are currently represented, these formats are very rarely interoperable. The use of standardised archetypes provides an interoperable way of representing and sharing these specifications, in support of consistent (good quality) health care record-keeping and the semantic interoperability of shared EHRs.

In the longer term, it is anticipated that the involvement of national health services, academic organisations and professional bodies in the development of archetypes will enable this approach to contribute to the pursuit of quality evidence-based clinical practice. In the future regional or national public domain libraries of archetype definitions might be accessed via the Internet, and downloaded for local use within EHR systems.”

What is clear here is that not only do we not know how many are needed, but that no-one knows, and more importantly the needed Archetypes do not exist anywhere on the planet!

If one considers the number of diagnostic tests, types of observations and so on that exist I believe “several thousand” is just hopeful guesswork. Of course who is going to develop and pay for all the work required is a separate question.

2. The writers of the quotation above seem to me to be conceiving Archetypes at a level (clinical guidelines and the like) above where Archetype development and definition is needed (i.e. at the level of individual observations and investigations). Only once these basics are developed and stable can construction of the more advanced information constructs and uses begin.

3. It is also obvious that without a global reference source for Archetypes (as well as global governance mechanisms and the required technical, development and managerial infrastructure) the stated goal of sharable, interoperable EHR extracts is little more than a pipe dream. This reference source does not exist and is unlikely to anytime soon. The prospect of local divergent Archetype repositories dotted all around the world, resulting in all sorts of interoperation difficulties, is too horrible to contemplate.

4. There is no reference implementation of a system deploying even a slightly comprehensive set of Archetypes to prove the conceptual and performance capability of Archetype based systems. There seems to me to be little doubt that scalability of Archetype services could be a significant issue.

5. There seems to be some evangelical thrust on the part of Standards Australia (and possibly NEHTA) to spread the use of Archetypes globally (as a special pestilential and mind befuddling treat for the rest of the world) when the local investment in their development and deployment has been minimal, to say the least. If they really think Archetypes are such a great idea putting ‘the money where their mouths are’ would be a good idea!

6. The literature supporting the contemporary use of Archetypes in the draft standard comprises a total of four citations predominantly by only two people.

7. The HL7 Template Special Interest Group is still working (as of October 2006) to resolve how CEN Archetypes and HL7 Templates can be harmonised in ways that make them interoperable whilst recognising that many of the conceptual and operational problems with Archetypes exist just as significantly in the HL7 Template proposals.

8. It seems to me there are much more basic and important things to be standardised before attacking a problem of this complexity which has not been applied or asked for by the real world. Getting basic clinical information available at local points of care reliably and improving care-coordination with the simplest of care records would be a very good start rather than developing this misguided, over-engineered and over-complex standard which I doubt will be seriously considered by more than 50 people and which I suspect will never be actually implemented as intended by its creators. To posit adoption of this Standard without describing the governance, provisioning and funding of the necessary Archetype sever infrastructure is naïve in the extreme.

To be creating 150+ page specification documents on the basis of what seems to be a conceptually ‘good idea’ and to then, without proven reference implementations, launch such documents on an unsuspecting world is downright dangerous.It is likely to hamper more useful and important e-Health developments globally, as an overly complex mess is sorted out – if that is possible.

It is really time for the proponents of Archetypes to ‘put up or shut up’. This is way to serious to just allow this proposed standard to wander though the approval processes without some very hard questions being asked.

Until reference implementations exist and are working and harmonisation with other standards (HL7 etc) is finalised and demonstrable all involved really need a ‘cold shower’ as our politicians are so keen on saying.

David.