What Difference HL7 V3 and CDA?

Question

What Difference HL7 V3 and CDA, really until now I haven't got precise answer please help me

Thanks.

Mcginty

Answer 1

HLv2.x is messaging protocol which was mostly ascii/text based, and also had an xml support to it. The problem was that HL7v2.x had boundaries for customization to about 20 percent That is why some times HL7 is also referred to as an open standard.

In order to scrap off customization, attain consistency and enable Plug N Play messaging, RIM - Reference Information Model was created. That gave an Object oriented approach to HL7 messaging standard.

Based on RIM, CDA Clinical Document Architecture was developed.If you say you using v3 or CDA both mean the same. v3 message is completely XML based allowing no region for customization unlike v2.7.

UPDATE: This question here also adds more information about the schemas used by v3 and CDA.

Key Differences

HL7 V2

1. Not “Plug and Play” – it provides 80 percent of the interface and a framework to negotiate the remaining 20 percent on an interface-by-interface basis
2. Historically built in an ad hoc way because no other standard existed at the time
3. Generally provides compatibility between 2.X versions
4. Messaging-based standard built upon pipe and hat encoding
5. V2 is what most people think of when people say “HL7″

HL7 V3

1. Approaching “Plug and Play” – less of a “framework for negotiation”
2. Many decades of effort over ten year period reflecting “best and brightest” thinking NOT backward compatible with V2
3. Model-based standard built upon Reference Information Model (RIM) provides consistency across entire standard
4. Messaging in XML format.
5. Clinical Document Architecture (CDA) is what most people think of when people say “HL7 V3″

Example

v3

<author>
<time value="200202150730"/>
<modeCode code="WRITTEN"/>
<signatureCode code="S"/>
<assignedEntity>
<id root="2.16.840.1.113883.19.1122.3" extension="444-444-4444"/>
  <assignedPerson>
     <name>
        <given>Harold</given>
        <given>H</given>
        <family>Hippocrates</family>
        <suffix qualifier="AC">MD</suffix>
     </name>
  </assignedPerson>
</assignedEntity>

v3 is under continous development. Even today, most of the healthcare applications, still continue to use v2.x.

Oscillatory

Answer 2

CDA are HL7 documents, while HL7 V.x are messages. Long story short, the CDA aims for human readability AND machine processing while messages only aim for machine processing.

Here's a good link which describes both paradigms.

A CDA is self-contained and static while a HL7 message describes a dynamic action on a object (A08 for example to update a visit's details or A05 to pre-admitt a patient.)

HL7 V.x messages are purely event driven while the content (Such as an OBX-5 field) may contain a static value. We for example used ORU messages to embedd x-ray results as binary stream.

Regenerate

Thanks Alex, but if I have a system builds clinical document upon a HL7 CDA standard and want to send this document to other party how I can do this, what HL7 V3 can do? – Mcginty

Are you using some sort of middleware for messaging or is it point-to-point? HL7 V3 could act as container for static CDA messages just as well. – Regenerate

CDA is a content standard and is not tied to any particular transport. You could use flash drive and carrier pigeon should you so choose however I would recommend against it as there are more reliable techniques :). Take a look at IHE profiles - specifically ITI XDS. ihe.net/Technical_Frameworks/#IT. – Alcaeus

Answer 3

I think you need to be a bit more specific on HL7. Do you mean HL7 V2 or HL7 V3.

CDA is a specific model created using HL7V3 ( and its underlying Reference Information Model ) to represent a clinical document. So in fact CDA is HL7v3, in as much it is an instance of a model created using HL7V3.

From my knowledge of CDA and the wider use of HL7V3, CDA is by far the most successful and widespread use of HL7V3.

Sovereign

This is correct. To add to this CDA was the first model (R-MIM) created from the RIM. No idea on whether it is still the widest in use, but I imagine it is at least near the top. Much of the US is still using HL7v2 for messaging whereas Europe and other places are using more of the HL7v3 messaging (as well as CDAR2) as they didn't jump in to the HL7v2 world as quickly as the US did and thus do not have the same level of legacy support. – Alcaeus

In the NHS Healthcare system the national architecture is based on HL7v3 messaging. Since deployed well over 1 billion HL7v3 message have flowed across the system. – Sovereign

Answer 4

CDA is an specification of HL7 v3. V3 is divided in domains, and CDA is like one specific domain for clinical documents. The Reference Information Model (RIM) of v3 is the general model for all v3 based standards, CDA is just one of those standards.

Locus

Answer 5

The CDA and HL7 v 3.x are synonymous.

Hide

This is incorrect. HL7 v3 is a family of domains, CDA is just one of those domains. – Locus