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Preparing for HL7 V3

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While HL7 V3 is still in the “early adopter” phase, there are now over 100 registered projects in progress worldwide involving V3 – the overwhelming majority being outside the United States. Some important points to keep in mind with this HL7 standard still in an early adopter phase:

  • Most deployments turn out to be rather custom based on realm-specific changes and that the current V3 standard is used as a starting point for a project – rather than the ending point.
  • V3 appears to be morphing even more into a reference model and less of a messaging standard.
  • Things are still in a relative state of flux as far as how V3 will be implemented by entities as evidenced with the National Health Service’s shift in the UK from using “V3 messaging” to “V3 CDA” for the Spine.

Keeping the above caveats in mind, it is still a good idea to prepare for V3 by acquainting yourself with some fundamentals.

With V3 being a model-driven standard, a logical starting point for preparation means starting with the information model upon which all V3 standards are based on – the Reference Information Model (RIM). This means that both V3 HL7 messaging standards (e.g., Inpatient Encounter, Ambulatory Encounter, etc.) and V3 Documents standards (e.g., CDA, CCD, etc.) are all based on the RIM.

As a side note, HL7 users in the United States generally think “HL7” means HL7 2.X messaging standard. Thus, when they think V3, they think about V3 messages replacing the V2 messages. While this is technically possible, market forces are not likely to make the leap to V3 for HL7 messaging anytime soon. If you work for a healthcare provider in the United States, outside of Clinical Document Architecture (CDA), there appears to be little movement towards V3. Some of these topics on the HL7 standards – V2 and V3 – are covered in more depth in a 14-page white paper entitled, The HL7 Evolution (PDF).

With this understanding, we can now get back to V3 and the RIM. With the RIM being an object-oriented methodology implemented via XML, a good starting point to understanding it is to familiarize yourself with the six core classes of the RIM:

  1. Act – represents the actions that are executed and must be documented as health care is managed and provided
  2. Participation – expresses the context for an act in terms such as who performed it, for whom it was done, where it was done, etc.
  3. Entity – represents the physical things and beings that are of interest to, and take part in health care
  4. Role – establishes the roles that entities play as they participate in health care acts
  5. ActRelationship – represents the binding of one act to another, such as the relationship between an order for an observation and the observation event as it occurs
  6. RoleLink – represents relationships between individual roles

With a firm understanding of the above six core classes and their associated attributes (see the latest HL7 Version 3 Normative Edition for details on associated attributes), you should be better prepared to more quickly analyze and implement your first HL7 Standard V3 interface, regardless of whether it is a V3 message or V3 document.

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David Li

David Li is an Implementations Consultant at Corepoint Health. Prior to Corepoint Health, David served as a Business Analyst Specialist with The Trizetto Group assisting payers with development of their member, provider, and consumer portals. Additionally, he has assisted many hospitals with numerous interfaces as a software engineer for a healthcare applications solutions provider.

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  • A footnote related to the use of V3 CDA vs v3 messages: if one asks those that have implemented both (i.e. the actual implementers, not the standards developers) then they see different use-cases (different parts of the overall workflow) that are either best covered by documents or by messages.

    As such it isn’t surprising that the English NHS is now using a mixture of v3 messages and v3 CDA documents to support its objectives. The use of documents (with the primary stated objective to be human readable, and with persistency as its manin characteristic) for the Spine (the archive part of the overall architecture) comes as no surprise. Other parts of the workflow, such as order communication, and patient/person demographics are better served by messages (transient information, status oriented).

    v3 messages/documents tend to be implemented within workflows that involve different healthcare entities, i.e. organizations that have different owners. If that type of communication doesn’t occur that much in a given country, adoption of v3 messaging will be slower than elsewhere.

    That’s why v3 CDA is much more of a success in the US than v3 messaging: v3 messaging is percieved to compete with v2 messaging, whereas v3 CDA has no equivalent in v2.

    -Ren

  • Interesting piece on HL7 v3. I spent a lot of time trying to implement a practical HL7 v3 solution. I quickly realized that to use it for messaging would be highly impractical. There are just too many possible interpretations of how to convey a message using the v3 messaging model. What I did find helpful however was the RIM (Reference Information Model) as a health-care data model.
    Mark Singh MD
    http://clinicore.blogspot.com/

  • Dr. Singh, I agree completely. The standard as a reference model is tremendously useful but as an implementation standard there are too many ways to interpret the specifications. For now, v2.5 provides all but the most advanced messaging – especially now that the xml spec is “official”.

    Thanks for this great article!

  • hi sir! Where can I find examples of XML built on CDA r2 like for discharge summaries or admitting notes?

  • Dear Sir,
    I appreciate this article, I’ve experience of implementation of V.2.x and now I’ve decided to implement the V.3. I’ve read lot of materials like V.3 Guide, MDF 3.0 and ITS but I’m still confused as how V.3 eliminates negotiation of Sender and Receiver by specifying pre-defined application roles. Another confusion is that whether HL7 provide us the repository that will have all related HMD’s related to our domain (for example HMD’s for Lab domain if I want to develop V.3 interface for test ordering and test results) or I’ve to develop my own.
    I need some kind guidelines from your side regarding V3.0 implementation and suggestion of reading materials.
    Regards

  • One thing i would like to point out in the debate of CDA documents vs V3 messages is that you can mine documents from V3 messages just as you can mine data from documents.

    But is it also not a fact that CDA-R2 and HL7V3 CSMP messages look almost the same with the usage of clinical statements and full usage of clinical coding.

  • Hi, just one thing about CDA documents and HL7v3 Messages. If you can implement CDA Documents, then you can implement HL7v3 Messages. Both are the same thing, just a customization of the RIM. If you understand RIM, you understand the rest. Of course, I’m talking from an implementation point of view. I agree with you that the HL7 v3 spec is very open for interpretation.

    Cheers,
    A/C Pablo Pazos Gutierrez

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  • Raja

    One of the things that bothers me with HL7 v3 is that no clear path to “migrate” from v2 has been proposed by HL7.org. In addition, with each hot-fix, the picture seems to get even more muddled.

  • David Li

    Raja, I’d agree that the lack of a clear “migration path” from v2 to v3 is one of the barriers to v3 adoption in the United States.

  • Adnan Siddiqui

    Can anybody send me the material for preparing for the HL7 V3.0 Certification. Virtually I cannot find any material on internet. Please send it to adnan_siddiquis@yahoo.com

  • Hi, I’m working on an implementation of an HL7 v3 interface for an already deployed health care system.

    I’ve been reading HL7 documentation, such as Version 3 Guide. I do understand that it should be implemented using XML. But I have almost same doubts Maqbool Hussain has: “does v3 provides us the repository that will have all related HMD’s related to our domain (for example HMD’s for Lab domain if I want to develop V.3 interface for test ordering and test results) or I’ve to develop my own?”
    And I also would appreciate some guidelines regarding v3 implementation and suggestion of reading materials.

  • Hi Guillermo,

    HL7 provides specification in the form of MIFs (Message interchange format). If you are HL7 member, surely you will have HL7 Normative 2006 and HL7 Normative 2008. With these normative CDs, HL7 provides the specification in the form of MIFs and XML schema. So you can create HL7 Generator/Parser that consumes these MIFs for manipulating HL7 V 3.0 messages.I hope it will be helpful for you.

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