term list s vs snomed ct subset
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Term list(s) vs. SNOMED -CT ® subset. 2 nd AAHA Software Vendors Summit – April 21, 2009. Lists of words…. Nomenclature The system or set of names for things Vocabulary A collection or list of words with explanations of their meanings Classification

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term list s vs snomed ct subset

Term list(s) vs. SNOMED -CT® subset.

2nd AAHA Software Vendors Summit – April 21, 2009

lists of words
Lists of words…
  • Nomenclature
    • The system or set of names for things
  • Vocabulary
    • A collection or list of words with explanations of their meanings
  • Classification
    • The result of classifying; a systematic distribution, allocation, or arrangement, in a class or classes; esp. of things which form the subject-matter of a science or of a methodic inquiry. (SNOMED)
lists of words1
Lists of words…
  • Terminologies are about information sharing, retrieval, aggregation and analysis.
  • It’s difficult if not impossible to justify the effort required to “do terminology right” from a data entry perspective.
  • A functional terminology must attend to both perspectives.
what do we need
What do we need?
  • Nomenclature ONLY
    • Provides a simple list for data entry
  • Vocabulary / Classification
    • We can be CERTAIN that the “term” (description in SNOMED) means what we think it means.
    • We can develop rules that allow us to combine concepts to express ideas more complicated than those contained in the nomenclature.
    • We can use the knowledge base supported by the vocabulary/classification to search, retrieve and analyze our data.
why a controlled nomenclature
Why a controlled nomenclature?
  • Aggregation of text-based content from multiple sources
    • Multiple individuals
    • Multiple institutions
  • Any time you rely on a computer to manipulate language and “meaning” is critical.
why a controlled vocabulary nomenclature
Why a controlled vocabulary / nomenclature?
  • Controlled vocabularies should automate recognition of and accurate substitution of synonyms.
  • Controlled vocabularies should facilitate retrieval and categorization.
complaints about snomed
Complaints about SNOMED
  • It’s too…
    • Big
    • Complicated
    • Expensive
  • Yes but…
    • We can make it smaller (sort of), and use small pieces (for most purposes).
    • Use it in simple and straightforward ways
    • But nothing, it’s expensive.
      • Not the license fees, the cost of making it work.
why pick something as big and complicated as snomed
Why pick something as big and complicated as SNOMED?
  • Viable nomenclatures must be maintained.
  • SNOMED is the ONLY actively maintained nomenclature that has veterinary content.
  • Veterinary medicine CANNOT afford:
    • to build it’s own competent nomenclature
    • to continue to live without a competent nomenclature
snomed history
SNOMED history










development history
Development history
  • SNOP
    • Morphologies
    • Morphologies, Etiologies, Locations
    • Same structure as SNOMED
    • Mix of existing SNOMED, additional veterinary content
    • Disorders, Morphology, Living organisms, social context
    • Veterinary content re-integrated
    • Logic based approach to SNOMED. Axes became hierarchies. Most significantly, the poly-hierarchic approach to classification.
    • SNOMED RT on steroids. Post merger with CTv3.
what do we get
What do we get ?
  • Sound technical solution to synonyms.
    • Ability to “localize” the synonyms
  • Compatibility with other “lists”
  • Ability to merge AAHA-based records with others (e.g., a cardiology specialty subset)
  • Functional Sub-setting
  • Enhanced queries
solution to synonymy
Solution to synonymy
  • Obvious duplicates in AAHA draft list:
      • AAHA Category = Hematology, Lymphatic, Endocrine
      • AAHA Category = Metabolic
  • (NOT) Obvious duplicates in AAHA draft list
    • Thyroid gland mass
      • AAHA Category = Hematology, Lymphatic, Endocrine
    • Mass, thyroid
      • AAHA Category = Neoplasm
    • In SNOMED, both = 237557003 = Mass of thyroid gland (finding)
local synonyms
“Local” Synonyms
  • It is POSSIBLE to allow practitioners to add their own favorite description of a concept.
    • Analysis / transmission by conceptID.
compatibility with other lists
Compatibility with other lists
  • AAHA list can be part of “mixed animal” system
  • AAHA list would integrate (could be used to query) a more granular specialty list.
functional sub setting
Functional Sub-setting
  • We only need PORTIONS of SNOMED
  • DIFFERENT portions of SNOMED needed for different contexts in HIS.
  • Retain the ability to use ALL of SNOMED to search, retrieve, analyze data produced using sub-sets.
  • Be prepared to transfer (copy) from SNOMED to subset as needs change.
functional subsets


“Cardiovascular disease” subset Algorithm



Cardiovascular Diseases

Intersection = Veterinary Cardiovascular Diseases

snomed subset
  • “…a set of Concepts, Descriptions, or Relationships that are appropriate to a particular language, dialect, country, specialty, organization, user or context.”
  • “…simplest form, the Subset Mechanism is a list of SNOMED identifiers (SCTIDs).”
  • “…may be used to derive tables that contain only part of SNOMED CT.”
  • Can be selected by clever query, if underlying definitions in SNOMED are sound.
existing subset s
Existing Subset(s)
  • Non-human subset
    • This subset assists applications that desire to exclude concepts which are not human medical concepts (i.e., paw and fin).
    • Note that this is NOT a veterinary subset as that subset would include terms shared with humans such as brain and eye.
  • Pathology subsets (3)
  • CAP Cancer checklists
  • Allergen subsets
aaha subset s
AAHA Subset(s)
  • SNOMED then remove hierarchies that are NOT of interest.
    • Someone has to decide what’s “not of interest”
      • Someone familiar with SNOMED
      • Someone with domain knowledge
    • Desired functionality
      • We think it’s important to distribute a subset of the hierarchy above the AAHA subset with relationships
        • Facilitate retrieval queries, may be possible to use the hierarchy to control “lists in correct context” (this does not currently exist.
subset development ideal
Subset development (Ideal)
  • Build a competent Veterinary Subset of SNOMED
    • Veterinary subset a resource shared by the profession.
      • Managed by central “authority”
      • Distributed by SNOMED?
  • Use algorithm approaches to create “microsubsets”
what we re doing instead
What we’re doing instead…
  • Intellectual investment (by AAHA) in a list of terms representing desirable small animal medical content.
  • “Mapping” by VTSL and EHRTF
  • Add “missing” content through SNOMED Extension mechanism.
  • AAHA terms expressed as SNOMED descriptions.
  • Permanent identifiers
mapping why we didn t just map aaha s list
Mapping (why we didn’t just map AAHA’s list).
  • Mapping is directional
    • Largely the result of differing granularity between “target” and “source”
      • 1:1 – Concept is the same
        • Term may be identical or synonym – remember to distinguish on CONCEPT not on string
      • Narrow to Broad – Source concept is more specific than target
      • Broad to Narrow – Source concept is more general than target
    • Two maps may be needed for bi-directional functionality (unless entire map is 1:1)
  • 1:1 maps will represent a majority
  • Broad (source) to narrow (SNOMED)
    • Good argument that SNOMED needs more content
  • Narrow (source) to broad (SNOMED)
    • SNOMED may need/want the content
    • Map to a post-coordinated concept may be required
aaha terminology development
AAHA terminology development
  • There is no “final version”
  • Walk don’t run
    • No syntax (post-coordination) just yet
    • Breadth first, depth later
snomed extensions
SNOMED Extensions
  • Enable authorized organizations (VTSL maintains two namespaces) to add Concepts, Descriptions, Relationships and Subsets to complement those that are centrally maintained as the core content of SNOMED CT.
  • specialized terminology needs of an organization.
    • ISIS / ZIMS
    • USDA
    • FDACVM
  • Extensions maintain unique identification across organizations.
snomed extensions1
SNOMED Extensions
  • Distinguishable from the main body of SNOMED CT
    • in the thesaurus
    • when stored in a patient record, query or decision support protocol.
  • Distinguishable from other Extensions, in the same way as they are distinguishable from the main body of SNOMED CT.
  • Able to be distributed and processed in the same way as equivalent components from the main body of SNOMED CT without requiring specific adaptations of SNOMED-enabled applications.
existing extension s
Existing Extension(s)
  • US Drug extension
    • List of drugs marketed in the United States
    • Veterinary drugs have not been maintained in some time.
  • UK Drug extension
what are we doing to the aaha diagnostic terms list
What are we doing to the AAHA Diagnostic Terms list?
  • Two reviews by VTSL veterinarians, third review by AAHA team.
  • Determining what each term MEANS
  • Mapping each term to SNOMED
  • Editing the terms
    • Slightly more natural English
    • Separating list of synonyms into individual descriptions
    • Limiting commas to one “use” only
    • Converting to sentence case
  • Providing SNOMED identifiers for each description
aaha terms version changes
AAHA Terms (version changes)
  • AAHA terms will have SNOMED-based identifiers
  • AAHA terms will be mapped to SNOMED concepts
  • Phrasings more like natural English
  • Only one use of commas
  • “Within-term” synonyms will be separate descriptions.
future project s
Future project(s)
  • Plan / build user request system
  • Characterize AAHA content
    • Patient findings
    • Laboratory findings
    • Morphologies
  • Add, then “clean up” upper hierarchy
    • Hierarchy to display "in appropriate context"
      • (Liver things show up when vet wants liver things).
  • Create similar specialty-based subsets
    • Increased specificity/granularity
      • Cardiology, Neurology, etc.