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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.