This page is based on this initial paper by Eric Browne, October 2008
HL7 CDA has been chosen by a number of organisations and communities as a standard to underpin clinical information exchange. This decision has resulted in a number of significant implementation challenges for those wishing to standardise and prescribe the content of specific document types, such as hospital discharge summaries, referrals, specialist reports, etc. A number of significant problems result directly from the way the computable entries in CDA documents are currently represented.
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Although HL7 has an extensive methodology and a number of tools to support the production of RIM-based models, XML schemas, message specifications etc., it falls down dramatically when it comes to supporting the design, communication and agreement of detailed clinical models. The situation will only become worse, in the near term, as the HL7 organisation tries to embrace more and more coded vocabularies and whilst other organisations such as IHE bring in profiles to try to lock down specifications for particular purposes, resulting in a proliferation of alternate specifications based on local requirements. Anyone needing to design, understand, communicate or use any of the various CDA related specification artefacts needs to be extensively versed in much of the HL7 RIM's architecture, language and undocumented usage practices. To become so versed takes years, for all but the most exceptional learners. The RIM has no associated tooling to facilitate easy CDA document design or specification communication!
The above problems all severely compromise the adoption of HL7 CDA as a widespread solution for clinical information exchange.
History
To many observers, the problems outlined above are all too familiar from the days of HL7 version 2. Version 2 has been extensively criticised for not having a good method for presentation of messages to humans. It has been extensively criticised for inconsistent representation of clinical concepts - "If you have seen one HL7 v2 message, you have seen exactly one HL7 v2 message". Version 2 has been criticised for lacking specialisation semantics. And Version 2 has been extensively criticised for lack of tooling and for an arcane specification representation that only trained experts can follow.
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