HL7’s Clinical Document Architecture (CDA) stores or moves clinical documents between medical systems. Documents are things like discharge summaries, progress notes, history and physical reports, prior lab results, etc. The CDA uses XML for encoding of the documents and breaks down the document in generic, unnamed, and non-templated sections.
HL7’s CDA defines a very generic structure for delivering “any document” between systems. What is missing in the CDA standard proper is a listing of the sections of that document. That is, a template of the expected sections that will appear in a given type of document. For example, on a history and physical document, sections could be named Current Medications, Prior Immunizations, Social History, etc.
Ignoring the political or technical motivation, an independent group at the ASTM was formed and worked to define an XML standard for moving documents between systems. Initially, this standard was unrelated to HL7’s CDA standard. It is fair to say the standards competed for mind share and each expressed a different integration philosophy.
In later efforts, the two standards groups agreed to effectively make the standards compatible with each other. The Memorandum of Understanding (MOU) between HL7 and ASTM says that they will “harmonize” the two competing standards. That’s a fancy way of saying they will play nicely.
In short, although not 100% technically correct, in HL7 training I like to describe the CCR as a specialization of the CDA. That is, the CCR provides a template of the expected sections that will be provided in CDA format. This CCR “content profile” is a tightly controlled list of document sections answering the “What major bits of data will be sent?” question. The CDA, then, is the structure of how the document will be formatted in XML.
There is a good overview of CDA and CCR over at the American Academy of Family Physicians web site.
There are also several related postings on this blog site:
- What is the Relationship Between the Continuity of Care Record (CCR) and HL7 2.X Messaging?
- What is the Continuity of Care Record (CCR)?
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