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Terminology and Terminology Services
Russell Hamm
Introductions
• Name: Russ Hamm
• Company: Intelligent Medical Objects
• Background: • Co-chair of HL7 Vocabulary Work Group• Co-chair HL7 Infrastructure Steering Division• Member of HL7 Technical Steering Committee• Active in HL7 terminology and modelling standards for 15+ years
Acknowledgements
• HL7 FHIR Community
• HL7 Vocabulary Community
• IMO FHIR Developers
Outline of Today’s Discussion
• Why terminologies are important in health information exchange
• Fundamentals of terminology elements used in exchanging coded data (Code Systems, Concepts, Value Sets)
• Terminology Services in support of terminology enabled healthcare applications
Electronic Health Data• Longitudinal Conception-to-Grave
• Retention for lifetime and beyond
• Comprehensive for all categories of clinical data• History, physical, pharmacy, laboratory, …
• All types and formats of data• Text, numeric, images, video, sound, coded, ...
• Legal record for all or part of a patient’s data
Why Terminology?
• Provide consistent meaning and promote shared understanding• Electronic health data sharing and portability
• Analysis and reporting
• Interoperability
• Facilitate communication between humans and computers
• Satisfy mandates and recommendations without replacing local systems and code systems
What is a Terminology?
• Defines a set of concepts each with a unique, coherent meaning
• May define relationships between concepts
• May define synonymous termsproviding alternative representations
• May provide additional information (properties) to further define concepts
Terminology
• Reference Terminology• Represent a large number and range of possible concepts in a consistent manner• Specify relationships between concepts• May not meet the requirements for ease of data entry
• Interface Terminology• Clinically relevant data entry• Fine grained and specific synonymy (alternate, common terms)
A combination of Interface & Reference Terminology may be required to meet both data entry and retrieval requirements
Types of Terminology• Developed specific to domains and uses in healthcare
• HL7 – Messaging and modelling• ICD-10-CM – Classification of diagnoses, symptoms, and abnormal findings• LOINC – Laboratory results, panels, nursing• RxNorm – Clinical drugs• SNOMED CT – Clinical reference terminology for clinical terms
• Often overlap between terminologies• Medications, labs, clinical diagnosis, billing• Terminology mapping is used to manage overlap and use
Value Sets
• Set of codes drawn from one or more code systems, intended for use in a particular context
• Diabetes Problem Patient Cohort Identification
• Heart Failure Problem Patient Cohort Identification
• Cystic Fibrosis Laboratory Results
Value Sets
• Persisted by its definition
• Value Set Definition (VSD) is a machine-processable expression that defines the allowable coded content (codes) that are members of the Value Set
• Value Set Expansion (VSE) is the collection of codes produced by processing the Value Set Definition
Value Set Definitions
• Extensional• Explicitly enumerate each of the Value Set concepts
• Intensional• An algorithm that, when executed by a terminology service (or interpreted by
a human), yields the intended set of concepts
Value Set – Extensional DefinitionClinical Quality Measure (CQM) Value Sets for “Statin Allergen": Includes seven codes from the RxNorm Code System
Developed by: United States National Library of Medicine Value Set Authority Center
Published on: 1-January-2018
This value set includes the following RxNorm codes:
• 301542: rosuvastatin
• 36567 : Simvastatin
• 41127: fluvastatin
• 42463 : Pravastatin
• 6472: Lovastatin
• 83367: atorvastatin
• 861634: pitavastatin
Value Set – Extensional Expansion
• Processing the extensional definition generates the resulting Value Set Expansion
• Pros• Will always resolve the same Value Set
Expansion• Easy to process
• Cons• Tedious to develop for large Value Sets• Version specific, will not include concept updates
in newer versions
Value Set – Intensional Definition
Value set "Nutritional Status": This is a value set that includes 34 concepts including filter rules to include or exclude the dependents of some concepts
Developed by: United States National Library of Medicine Value Set Authority Center
Published on: 1-July-2018
Value Set – Intensional Expansion
• Processing the intensional definition generates the resulting (truncated) Value Set Expansioncontaining 123 concepts.
• Pros• May resolve a different Value Set Expansion
based on the Value Set Definition (i.e. is the definition tied to a specific code system version?)
• Cons• More advanced tools needed to generate both
the Value Set Definition and Expansion• Definition alone may not be useful (most people
just want the codes)
FHIR Representation of Terminology
• FHIR supports representation of Terminologies (Code Systems) and Value Sets
• Resources defined in the Terminology Model Module
• Foundation for representing coded data for both externally-defined standard and FHIR-defined terminologies
FHIR – Code System
• Identifying URL • Code System Version• Metadata such as description, copyright,
publication date, etc.• Key properties such as case sensitivity, version safe,
compositional grammar, etc.• Properties of the concepts themselves• Some or all of the concepts in the code system
including, code, display, definition, designations, etc.
FHIR - Coded Data Types
• Coded values are typically systemand code
• code*, Coding, CodeableConcept
FHIR - Coded Data Types• code
• Primitive data type• Represents the code only. Code System is implicit - defined as part of element definition; not
carried in the instance
• Coding• Complex data type• Referenced as a tuple: Code and Code System
• CodeableConcept• Complex data type• Plain text and/or one or more Coding elements• Collection of Coding for same concept – e.g. ICD-10 and SNOMED CT coding for Diabetes Type II
FHIR – Value SetFHIR Value Sets select from one or more Code Systems for a given context or use case
• FHIR Condition Clinical
• Heart Failure Problem Patient Cohort Identification
• Cystic Fibrosis Laboratory Results
FHIR - ConceptMap
• Defines a mapping from a set of concepts defined in one terminology to one or more concepts defined in other terminologies.
• Standard and local terminologies
• Equivalence (how similar a concept is to another) and context (business case) of the mapping
Terminology Services
• Mechanism for applications to interact with, and operate on terminology elements
• Take advantage of the knowledge in the underlying terminology model• Interoperate among various standard and local terminologies
• Software• Centralize terminology content• Represent terminology consistently• Standardize access to disparate terminologies (as much as possible)
Terminology Services Use
• Informaticians to create, extend, localize, subset, and map terminologies
• Interface applications to translate data elements between applications
• Clinical applications to select and standardize captured clinical data
Examples of Terminology Service Operations• Term/name normalization:
What is the SNOMED CT name for Tennis Elbow?
• Billing code translation: What is the ICD-10 code for Lateral Epicondylitis?
• Grouping and aggregation:Is Lateral Epicondylitis a soft tissue disorder?
• Clinical knowledge:Find a short-term treatment for Lateral Epicondylitis?
• Code Translation:
What is the RxNorm Code for Methylprednisolone?
Lateral Epicondylitis
M77.11
Yes
Methylprednisolone
1357886
Terminology Service Deployment
Application layer deployment• Separate terminology server used to manage and maintain controlled
vocabularies • Terminology data exported and loaded into local applications
ClinicalApplication
TerminologyServer
TerminologyServer
Real-time terminology services• Applications communicate directly with the
terminology server• Provide access to Terminology Model
knowledge (subsumption and concept model)• Global or regional deployment
ExportedData
ClinicalApplication
FHIR Terminology Services
• Provide a simple set of functions built on the definitions provided by a collection of CodeSystem, Value Set and ConceptMap resources
• Build on the basic principles for using terminologies in FHIR
• Terminology Service Capability Statement defines the operations and content supported by each service
FHIR Terminology Service Operations – CodeSystem
• $lookup• Get additional details about a coded value, including definition, status, designations, and
properties.
• $validate-code• Validate that a coded value is in the code system.
• $subsumes• Test the subsumption relationship between two coded values
• $find-matches• Return one or more possible matching codes given a set of properties (and text)
FHIR Terminology Service Operations - ValueSet
• $expand• Value Set Definition used to create Value Set Expansion
• $validate-code• Validate coded value is in a Value Set Expansion
FHIR Terminology Service Operations - ConceptMap
• $translate• Translate a code from one Value Set to another
• $closure• Provide support for ongoing maintenance of a client-side transitive closure table based
on server-side terminology logic
FHIR Terminology Services
• Some available FHIR Terminology Services
• Apelon DTS – Open source, and a full blown terminology service that is filling out their FHIR API• Art-Decor – FHIR API to the content in art-décor• FHIRServer (Grahame Grieve’s server)• HAPI – Provides some terminology services but I’m not sure how complete and tested this is• IMO FHIR Demo Server – Standard Terminologies and Value Sets• Ontoserver – Official terminology service for Australia. • Terminz – Terminology services for New Zealand• VSAC – US Value Set Authority Center
Summary• Terminologies
• Provide the conceptual framework to unambiguously represent data for electronic health information sharing and portability.
• Provide consistent meaning for data to promote shared understanding essential for interoperation among systems and applications.
• Terminology Services are the mechanism for to applications interact with and operate on terminology elements.