HL7 development in 2007/8

1. HL7 development in 2007/8 Rik Smithies Chair HL7 UK NProgram Ltd, CFH

2. HL7 development Clinical Statement • Reached DSTU, Sept 2007 • The model for structured (coded) clinical data in HL7 • Actually been more or less constant for some time.

3. HL7 development Clinical Statement / CDA • Started life in GP2GP project, pre-NPfIT • Now part of the foundation for CDA • Success of CDA partly that CS part optional • But there for the full structure when needed • CDA is V3, not an easy alternative, it’s easy V3.

4. HL7 development (Digression into) CDA • Unlike rest of V3 you don’t create a message design with CDA • CDA is the message, pre-built • No tooling necessary, no need to deeply understand V3 modelling from scratch. • You specialise CDA how you like, with written documents if required. • “Use this code in this section, don’t use that section”

5. HL7 development CDA • You can also ‘constrain’ with V3 modelling (CFH method) • In practice you will probably want some machine processable constraints to narrow down CDA use. • Generated schemas, generated schematrons, or hand made schematrons.

6. HL7 development Templates • Also passed DSTU September 2007 • Typically used on top of CDA • Adds rigour and specialisation for local needs • Small patterns of data used to tighten another model • Can be diagrams (V3 RIM models) • Can be text in a paper document – zero bar to entry. • But must be valid additional statements about V3 model • “Don’t use this class of the standard CDA” • “This part of the message must use code X even though CDA allows any code here”

7. HL7 development Templates • been around almost as long as Clinical Statement • Much confusion as to what they were • Various apparently different techniques • Realised that technique not the key • but the fact of an additional constraint on an underlying model, however expressed

8. HL7 development Templates • Much UK and HL7 UK input to the specification • especially on the diagram based constraint style • CFH tooling to support this approach • Other tooling exists to convert “structured english assertions” to machine checkable rules.

9. HL7 development TermInfo • Third part to get DSTU in Sept 2007 • Means “Terminology Model/Information Model” • How to fit a terminology model specifically SNOMED codes into an Information Model namely HL7.

10. HL7 development TermInfo • “codes” often duplicate things you can do with message models • eg HL7 has slot for procedure method • SNOMED allows specifying method in the code itself • 2 ways to say the same thing • reinforcing? doubling? contradicting?

11. HL7 development TermInfo • TermInfo lays down the rules for how SNOMED and HL7 work together • CFH had adopted a pragmatic position • early SNOMED adopter. • UK ideas drove TermInfo standard • quite a bit of resistance • compromise won out • CFH position compatible with outcome

12. HL7 development Other changes: • PA (Patient Admin) • Produced structure for UK style Registered GP • after requirements raised by HL7 UK TC • Tooling • CFH leading on tooling, update later.

13. HL7 development Other changes: • Datatypes V2, balloting now. • Set of building blocks (basic types) • UK input • Improved for UML tooling compatibility and to harmonise with other standards. • V2 – update later.

14. HL7 development RIM Based Architecture • New thinking in HL7 • Started in the Netherlands • Realised several production systems used V3 RIM as their internal model • Unexpected since “V3 is just messaging, right?” ~ lore • But messages are clinical models in own right • RIM supports wide range of data for messaging • A RIM based system therefore supports a wide range of medical data, in a single model

15. HL7 development RIM Based Architecture • Meeting convened at January WGM • Existing HL7 Java group have similar code • Parses, digests, stores, creates HL7 V3 messages • By understanding just the RIM • Running in live environment • RIM has rigour to support implementation • It works - not well publicised! • Good validation of the RIM as a general purpose reference model • “It’s not just messaging”