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Introduction to Vocabulary Russell Hamm Informatics Consultant Apelon, Inc. Co-chair HL7 Vocabulary WG Adapted from Ted Klein, CG Chute MD DrPH, Stan M.

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Presentation on theme: "Introduction to Vocabulary Russell Hamm Informatics Consultant Apelon, Inc. Co-chair HL7 Vocabulary WG Adapted from Ted Klein, CG Chute MD DrPH, Stan M."— Presentation transcript:

1 Introduction to Vocabulary Russell Hamm Informatics Consultant Apelon, Inc. Co-chair HL7 Vocabulary WG Adapted from Ted Klein, CG Chute MD DrPH, Stan M. Huff MD, Beverly Knight, Cecil Lynch MD, Russ Hamm HL7 Tutorial May, 2009 St. Paul, MN (Yay!)

2 March, © , Health Level Seven, Inc. Outline Why Terminology Terminology Basics Terminology Services

3 March, © , Health Level Seven, Inc. What is the Role of Vocabulary? Defines the meaning of data – i.e. changes data to information through instantiation of semantic rules Is the Human readable value a user sees Allows for intersystem interoperability by disambiguation of the message payload Required for –data translation –data aggregation Is the single most important component for interoperability

4 March, © , Health Level Seven, Inc. What is a Structured Terminology? A structured terminology is composed of concepts along with synonymous terms, properties and various relationships, especially a taxonomy Relationships –Taxonomy (is-a) –Partonomy (part-of) –Etiology (caused-by) –Therapy (treated-by) –Position (located-in) –…–…

5 March, © , Health Level Seven, Inc. Structured Terminology Elements Concepts represent unique ideas Codes uniquely identify concepts Terms refer to concepts Typically –Humans communicate concepts using terms –Computers communicate concepts using codes Concepts are language independent; terms are dependent Myocardial infarction (disorder) Myocardial disease (disorder) Heart disease (disorder) Myocardial finding (finding) Disorder of Myocardium Disorder of heart muscle Myocardial disease, NOS Cardiac disorder Cardiopathy Disorder of heart Heart disease, NOS Morbis cordis Myocardial observation Myocardial infarction MI Cardiac infarction Heart Attack infarctus du myocarde

6 March, © , Health Level Seven, Inc. Example scenario 1.English term entered by clinician to represent an idea 2. Term is encoded in SNOMED 3. Code is recorded in Electronic Health Record 4. Record is retrieved 5. Record is transmitted to another application or institution 6. Code is extracted 7. Term is requested e.g., French term Consumer term French consumer term Interplay among Terminology Elements

7 March, © , Health Level Seven, Inc. Why Code Data? (translation and understanding) Cold –February is a cold month. –She met his gaze with a cold stare. –Julia is in bed with a cold. February is a month. She met his gaze with a stare. Julia is in bed with a

8 March, © , Health Level Seven, Inc. Data Aggregation TermDescription IDConcept ID myocardial infarction cardiac infarction heart attack myocardial infarct MI - Myocardial infarction infarction of heart

9 March, © , Health Level Seven, Inc. Strategic Role of Vocabulary Interface to Knowledge Resources –Guidelines, Critical Paths, Reminders –Decision Support, Reference Support Practice Analysis –Quality Improvement –Clinical Epidemiology –Outcomes Analyses

10 March, © , Health Level Seven, Inc. Outline Why Terminology Terminology Basics Terminology Services

11 March, © , Health Level Seven, Inc. Terminology Definitions A set of concepts, designations, and relationships for a specialized subject area The terms that are characterized by special reference within a discipline are called the terms of the discipline and collectively form the Terminology. Terms that function in general reference over a variety of languages are simply words, their totality is a Vocabulary.

12 March, © , Health Level Seven, Inc. How do we represent patient data? Reference Terminologies –SNOMED CT®, LOINC® High Level Classifications –ICD-10 Terminologies with a specific purpose –DPG – Day Procedure Group –CMG – Case Mix Groups Within the context of information models –ISO, HL7, openEHR, …

13 March, © , Health Level Seven, Inc. Types of Clinical Terminologies

14 March, © , Health Level Seven, Inc. Reference Terminologies VS Interface Terminologies Reference Terminologies Represent a large number and range of possible concepts in a consistent manner Specify relationships between concepts Meet requirements for a semantic foundation for reliable retrieval –Based on inherent meaning –Independent of initial purpose of collection May not meet the requirements for ease of data entry Interface Terminologies Assist entry and display of information –Synonyms, etc (alternate or common terms) –Provides a national refinement option Provides consistent data entry Does not meet the requirement for data retrieval based on implicit meaning A combination of Interface & Reference Terminology features is required to meet data entry AND retrieval requirements.

15 March, © , Health Level Seven, Inc. Terminology Models May consist of the following attributes Code system Code system version Concept Code Concept Designation Concept Property Concept Relationship

16 March, © , Health Level Seven, Inc. An example of a Terminology Information Model

17 March, © , Health Level Seven, Inc. Concepts Concept defines a unitary mental representation of a real or abstract thing; an atomic unit of thought Should be unique in a given terminology May have synonyms in terms of representation May be a primitive or compositional term

18 March, © , Health Level Seven, Inc. Coded Concept A Coded Concept is unique within the Code System that defines it. Coded Concepts may be characterized by zero or more Concept Properties. A Coded Concept has the following minimal attributes: – code - an identifier that uniquely names the class or "concept" within the context of the defining Code System. – status - represents the current status of the Coded Concept within the Code System.

19 March, © , Health Level Seven, Inc. Metadata Data about a datum Allows for a full description of a data element such that the data element can be classified and potentially reproduced Provides the necessary information to allow vocabulary interoperability Example includes the following LOINC code : –GLUCOSE: –SCNC: –PT: –UR: –QN: –TEST STRIP metadata

20 March, © , Health Level Seven, Inc. Concept Domain Definition: –An HL7 Concept Domain is a named category of like concepts that will be bound to one or more coded elements. –Concept Domains exist to constrain the intent of the coded element –Concept Domains are independent of any specific vocabulary or code system or Realm –They exist at the Universal level only and ALL must be registered at HL7 international. May further constrain the intent of a Concept Domain by creating a Sub Domain (& therefore create a hierarchy) Provides a high level grouping for all things possible in a given domain from which value sets will be constructed Naming rules have been created to provide consistency Examples: –OrderableLabType

21 March, © , Health Level Seven, Inc. Code System At various times referred to as an ontology, classification, terminology, or code set/table. Within the HL7 context, a collection of codes with associated designations and meanings –Concept codes within a code set must not change meaning. –Codes may be added or retired –Definitions may be clarified –New relationships may be established –Codes must not be reused –Names should be unique –Code systems have versions –Contain codes & synonyms –Print names at the concept & code level Can have more than one print name –Have semantic relationships between them & hierarchies –Some allow post co-ordination (eg UCUM & SNOMED CT)

22 March, © , Health Level Seven, Inc. Code System (continued) Code systems may vary in size and complexity from a simple code/value table… CodeValue MMale FFemale UUndifferentiated … to a complex reference terminology containing many 100,000s of concepts, relationships and the like.

23 March, © , Health Level Seven, Inc. Code System Examples LOINC CPT-4 NIC NOC ICD-9-CM ICD-10 SNOMED International SNOMED-CT ISO 4217 Currency codes ISO Country Codes IETF Mime Types HL7 Version 2 Table 1 ISO 639 Language Codes International Airport Codes IANA Character Sets HL7 Version 3 Administrative Gender HL7 Version 3 ActClass …

24 March, © , Health Level Seven, Inc. Value Sets A Value Set represents a uniquely identifiable set of valid concept representations, where any concept representation can be tested to determine whether or not it is a member of the value set. Value sets exist to constrain the content for a coded element in an HL7 static model or data type property. Value sets cannot have null content, and must contain at least one concept representation. All have an OID & may have its own name Can refer to a specific version of a code system They can exist in UV as X_Domains (although do not need this format for the name any longer) Can create a sub-Value Set Value set complexity may range from a simple flat list of concept codes drawn from a single code system, to an unbounded hierarchical set of possibly post-coordinated expressions drawn from multiple code systems. Can be expressed as –Enumerated (or extensional) specifies a complete set of codes –Intentional (or definitional, expression) filter or rules are defined to specify the allowable codes Can consist of codes from one or more code systems BUT cannot have representations of a single concept from more than one code system

25 March, © , Health Level Seven, Inc. Structural Vocabulary Vocabulary intended to define the structural classes in a data model from which objects can be created –Examples; the HL7 Version 3 structural codes that define Class Codes, Mood codes etc. or a high level namespace in an ontology model describing a grouping for more primitive concepts such as Living Organism with sub-classes of Virus, Bacterium, Fungi, Parasite These codes identify information structures in HL7 that are used to inform the message objects that will carry the clinical data; they are not generally the clinical objects! The value of this kind of code carried in a data element may not change after the class in which it appears is instantiated

26 March, © , Health Level Seven, Inc. Descriptive Vocabulary Defines the terms and codes for concepts The data used to populate a data element Provides the core component for system and data interoperability Examples: –Anthrax –Gram negative rod –centrifugal rash –MRI of brain These are the information payload that are carried in the fields in a message or an information model instance

27 March, © , Health Level Seven, Inc. Binding Realms Defines the interoperability space Restricts what may be carried in a coded model element –May restrict (instantiate) a Concept Domain, being bound to it within a Realm (Representative Realm Binding –May be bound directly to the model element (universally where the model is used) There are 4 types of Realms (Universal, Representative, Example & Unclassified) –Universal constitutes the core HL7 realm which by definition is invariable. Structural elements and most datatypes are examples of contents in this realm. –Representative content that provide a plausible basis for adoption across specialized (including geographic) realms (ie Allows jurisdictions to author value sets, templates, and content) Content must be sufficiently comprehensive and internally consistent to be adoptable and implementable by specialized realms. Affiliates may choose to use an existing representative value set when determining what bindings to use within their binding realm – Example In the absence of Representative Realm HL7 provides a Realm to designate content with no expectation to be complete or implementable. –Unclassified a realm that can accommodate content that is new and being created or legacy content that has not yet been promoted to one of the three main realms.

28 March, © , Health Level Seven, Inc. Terminology Binding Terminology Binding is the link between the terminology component and the message model and determined by the Binding Realm. Concept Domain in the message model is tied to a value set with the terminology (with a start & end date) The binding may be to a specific set of codes or a changing set of codes Static Binding - the allowed values of the value set do not change automatically as new values are added to a value set. Dynamic Binding - the intent is to have the allowed values for a coded item automatically change (expand or contract) as the value set is maintained over time

29 March, © , Health Level Seven, Inc. Global Uniqueness (OIDs) All identifiers must be globally unique and OIDs (Object Identifiers) are used to achieve uniqueness Sequence of integers representing a Registration Authority tree –…a convenient mechanism for assigning world-unique identifiers to standard-related objects 1 Each OID uniquely identifies something –Could be a Registration Authority (such as HL7) –Could be a Registered Object (such as LOINC) New entries can be registered in a de-centralized fashion

30 March, © , Health Level Seven, Inc. Global Uniqueness (OIDs) Used in health informatics for uniquely identifying entities, concepts & events Five types of OIDs –Common Public Identifiers Real-world identifiers which are known by humans & frequently used outside of the direct business relationship with the issuer of the identifier (e.g. SIN, drivers license) –Local Public Identifiers Typically generated by generated by clinical systems & communicated in their message (e.g. lab order or prescription #s) –Private Identifiers Include identifiers necessary for smooth operation of automated systems & not used by practitioners or patients (e.g. event, query, application identifiers) –Common Code Systems Include all code systems intended for use where the organization responsible is not the sender/receiver (e.g. LOINC®, SNOMED CT®) –Local Code Systems Those that are only used in communication by or with the organization responsible for creating that code system (e.g. internal lab test codes).

31 March, © , Health Level Seven, Inc. Outline Why Terminology Terminology Basics Terminology Services

32 Common Terminology Services (CTS)

33 March, © , Health Level Seven, Inc. What CTS is An HL7 ANSI standard – Defines the minimum set of requirements for interoperability across disparate healthcare applications A specification for accessing terminology content –The CTS identifies the minimum set of functional characteristics a terminology resource must possess for use in HL7. A functional model –Defining the functional characteristics of vocabulary as a set of Application Programming Interfaces (APIs)

34 March, © , Health Level Seven, Inc. The Problem Terminology systems vary considerably in both content and structure. –NDF-RT –RxNorm –SNOMED-CT –ICD-9 and ICD-10 –CPT Requirements of terminology vary widely Implementation decisions of terminology vary widely Storage formats may differ (relational database, XML,...)

35 March, © , Health Level Seven, Inc. Common Terminology Services (CTS) Purpose is to specify a common Application Programming Interface (API) to access terminological content Client software doesnt have to know about specific terminology data structures and/or how to access them Server software can plug and play with many clients

36 March, © , Health Level Seven, Inc. CTS API Application Service Interface Data CTS...

37 March, © , Health Level Seven, Inc. CTS API CTS MS Access Tables Application Service Interface Data HL7 Vocab Browser HL7 Terminology Server Find codes having *myelitis Select * from VOC_concept_designation WHERE text like %myelitis

38 March, © , Health Level Seven, Inc. CTS API – Different Client, Same Service IHC Picklist Tool MS Access Tables Application Service Interface Data HL7 Terminology Server Find codes having *icillin Select * from VOC_concept_designation WHERE text like %icillin CTS

39 March, © , Health Level Seven, Inc. CTS API – Different Server, Same Client IHC Picklist Tool SNOMED CT Oracle Tables Application Service Interface Data APELON DTS Find codes having *icillin Select * from conc_repr WHERE text like %icillin AND... CTS

40 March, © , Health Level Seven, Inc. CTS API – Distributed Services IHC Picklist Tool Internet Service Application Service Interface Data Find codes having *icillin CTS Web Portal

41 March, © , Health Level Seven, Inc. Common Terminology Services API Allows Client Software to be developed Independently from Service Server Software Allows Terminology Plug-and-Play Allows Client Plug-and-Play Defines a Functional Contract

42 March, © , Health Level Seven, Inc. Common Terminology Services Message Processing Application Vocabulary Message Processing Application Message API Vocabulary API

43 March, © , Health Level Seven, Inc. Common Terminology Services RuntimeBrowser Message API Message RuntimeMessage Browser Vocabulary API Vocabulary Runtime Vocabulary Browser Mapping / Translation Vocabulary Mapping Services Are Also Partitioned by Function

44 March, © , Health Level Seven, Inc. Code System – CTS Model

45 March, © , Health Level Seven, Inc. CTS Runtime Message API Examples FunctionDescription validateCode Determine whether the supplied coded attribute (CD) is valid in this vocabulary domain and context. validateTranslation Determines whether the translation portion of the coded attribute is valid in this domain and context. translateCode Translate the input code into a form that is valid in the target contexts.

46 March, © , Health Level Seven, Inc. CTS Runtime Message API Examples FunctionDescription fillInDetails Fill in the details for the coded attribute, including all code system names, versions and display names. subsumes Determine whether the parent attribute subsumes the child. areEquivalent Determine whether attribute value 1 and 2 are logically equivalent lookupValueSetExpansion Return a hierarchical list of selectable concepts for the vocabulary domain and context

47 March, © , Health Level Seven, Inc. CTS Runtime Vocabulary API FunctionDescription lookupCodeSystemInfo Return detailed information about the named code system isConceptIdValid Determine whether the concept code is valid in the code system. lookupDesignation Determine whether the relationship exists between the source and target code

48 March, © , Health Level Seven, Inc. Additional CTS APIs CTS Message Browsing API –Used by HL7 Modelers CTS Vocabulary Browsing API –Used by HL7 Terminology Authors and Value Set Building CTS Mapping API –Used to translate concept codes from one system to another Details can be found on HL7 Ballot spec

49 March, © , Health Level Seven, Inc. Common Terminology Services Interface specification –Different message processing applications, same functions –Different terminology structures, philosophy – same behavior Language Bindings –(Currently) specified in OMG IDL –Java interface binding –Java bean binding –WSDL/SOAP binding Version 1.0 Finalized Spring 2004 –CTS1 balloted and adopted as an ISO standard Fall 2008 Version 2.0 Balloted Spring 2008

50 March, © , Health Level Seven, Inc. Common Terminology Services Resources: Specification: –http://hl7.orghttp://hl7.org Implementations :

51 March, © , Health Level Seven, Inc. CTS 2 CTS I Limitations –Varying Vocabulary Formats –Varying repository formats –Vocabulary content overlap CTS 2 –Functional Specification –Functionality Enhancements Terminology Authoring Management of Terminology Versions Enhanced Terminology Mapping Functions –SOA SIG / HSSP –Based on a common model for vocabulary Terminology Use and Development Lifecycle Model

52 March, © , Health Level Seven, Inc. CTS 2 Status Being worked on by a long list of contributors –IHTSDO –Mayo Clinic –GE, Apelon –UC Davis, Emory –Others… Was balloted as a DSTU in March 2009 Comments are going through the disposition process Is being updated with the new HL7 vocabulary model –Currently only implemented in the MIF Current plan is to ballot CTS 2 as a DSTU in the March 2009 ballot cycle

53 March, © , Health Level Seven, Inc. Conclusions Vocabulary covers a lot of territory Critical component for interoperability There is a lot more involved than a table of mnemonics There are significant resources available Come and contribute in the Vocabulary Technical Committee! Questions? Thank you very much!

54 March, © , Health Level Seven, Inc. Thank you Russell Hamm Informatics Consultant Apelon, Inc.


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