The document discusses using FHIR terminology services to access SNOMED CT. It describes the complexity of terminologies and need for consistent implementation. FHIR provides a standard way to build terminology APIs to address common application needs like retrieving codes, validation, translation and search. Value sets in FHIR can represent subsets of codes from SNOMED CT and be expanded for use. A New Zealand implementation example is provided.

1. FINDING WITH FHIR
HL7NZ Standards Workshop– June27, 2016
Accessing SNOMED CT With
FHIR Terminology Services
PeterJordanMScLLBMCPD
Vice-ChairHL7NewZealand

2. Page 2 • HL7 New Zealand
The SNOMED CT Landscape in NZ
• Comprehensive Terminology > 300,000 active concepts…each with
multiple descriptions & relationships.
• Endorsed by MoH for EHR clinical content coding at point of care.
• Replacing Read Codes in primary care.
• Numerous implementation options…
 A code system – store information
 An interface Terminology – capture & display
 An indexing system - retrieve
 A common terminology – meaningful communication & integration
 A dictionary – query, analyse & report; link health records to
knowledge resources
• 2016 SNOMED CT Expo: Oct 27-28 Wellington

3. Page 3 • HL7 New Zealand
The Problem
• Terminology is HARD: very few – if any – existing
systems do it well.
• Consistency required for clinical safety and
downstream uses (analytics, research, etc.).
• Friendly & efficient UIs (controls or text + Natural
Language Processing?)
• HIE issues are common to ALL systems
• Risks of individual implementation approach
– Inconsistent implementations – e.g. pre or post coordination?
– Version Lags if Facility/Vendor based deployment
– Duplicate/Overlapping Reference Sets
– Inconsistent Mapping to Read (NZ variations)

4. Page 4 • HL7 New Zealand
Mitigation
• Sector-wide implementation
• National Release Centre – single source
• National Reference Sets
• Single set of NZ Read to SCT maps
• Terminology Services
• Common standards-based APIs

5. Page 5 • HL7 New Zealand
Terminology Services
• Repository of coded clinical concepts, descriptions &
relationships plus tools for maintenance of vocabulary
resources, but…
• There’s a lot of complexity here:
o Code Systems / Ref Sets / Value Sets / Bindings
o Value Sets are complex (intensional, extensional, implicit)
o Underlying terminology logic much more complex (expressions)
• Most applications much simpler
o List of codes and displays in some table structure
o This is a known problem – in many countries

6. Page 6 • HL7 New Zealand
Terminology Services API
• Bridge the Gap: delegate all this complexity to
specialist software
• Provide a set of services that do what
applications need
• It becomes easy to write applications that do
terminology well
• FHIR – a framework well-suited to building these
APIs.

7. Page 7 • HL7 New Zealand
Application Needs
• Give me a list of codes (filtered
by term, super type, expression)
• How do I display this code?
• Is this code valid?
• Translate this code to a different
code system
• Integrate terminology search
into my application (including
client-side caching)

8. Page 8 • HL7 New Zealand
Application Needs API Gives
• Give me a list of codes (filtered
by term, super type, expression)
• How do I display this code?
• Is this code valid?
• Translate this code to a different
code system
• Integrate terminology search
into my application (including
client-side caching)
• $expand
• $lookup
• $validate-code
• $translate
• $closure

9. Page 9 • HL7 New Zealand
FHIR Terminology Resources
• Code System – defines a set of codes with meanings, e.g.
URL, version, description, key properties, filters
• Value Set – selects a set of codes from one, or more, Code
Systems constructed from…
 Inline code system or..
 Set of codes defined in other code systems, e.g. SNOMED CT by listing
the codes (extensional) and/or providing selection criteria
(intensional)
 Can be expanded – turned into a simple collection of enumerated
codes & descriptions, ready to use for data entry or validation.
• Concept Map – mappings between Code Systems

10. Page 10 • HL7 New Zealand
Using SNOMED CT With FHIR Value Sets
• Implicit Value Sets
o defined as part of each request
o provide a interface to distinct subsets
o basis for $expansion operations [base]/ValueSet/$expand
o URLs with base identifier
?identifier=http://snomed.info/sct/ 900000000000207008 /version/20160131
…plus a query portion defining scope…
o All concepts in the edition/version /fhir_vs
...but maybe add a text filter! /fhir_vs&filter=midlife
o All concepts subsumed by (descendants of) another concept
/fhir_vs=isa/38341003
o All concepts in specified reference set /fhir_vs=refset/450970008

11. Page 11 • HL7 New Zealand
NZ Implementation Example
• Patients First Terminology Server
http://its.patientsfirst.org.nz/RestService.svc/Terminz
NB: Display preferred terms, rather than fully specified names.

12. Page 12 • HL7 New Zealand
Questions and Comments?
Next steps…beta testing!
Test Page: http://itp.patientsfirst.org.nz/Home/Terminology
Feedback to peter.jordan@patientsfirst.org.nz