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.

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.

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.