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

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

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)

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

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

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.

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)

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

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

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

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.

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