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Term list(s) vs. SNOMED -CT ® subset. 2 nd AAHA Software Vendors Summit – April 21, 2009.

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Presentation on theme: "Term list(s) vs. SNOMED -CT ® subset. 2 nd AAHA Software Vendors Summit – April 21, 2009."— Presentation transcript:

1 Term list(s) vs. SNOMED -CT ® subset. 2 nd AAHA Software Vendors Summit – April 21, 2009

2 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)

3 Lists of words… Terminologies are about information sharing, retrieval, aggregation and analysis. Its 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.

4 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.

5 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.

6 Why a controlled vocabulary / nomenclature? Controlled vocabularies should automate recognition of and accurate substitution of synonyms. Controlled vocabularies should facilitate retrieval and categorization.

7 Complaints about SNOMED Its 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, its expensive. Not the license fees, the cost of making it work.

8 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 its own competent nomenclature to continue to live without a competent nomenclature

9 SNOMED history Reduce storage sizeReduce Storage sizeStorage not an issue Categorize informationMultiple code-based mono-hierarchies Poly-hierarchical categorization Functional Subsets Pathology contentAll Medicine Veterinary content separate, then integrated SNOVET DOES NOT EXIST Integrated content Computability for retrieval. Natural language, artificial intelligence, decision support SNOP SNOMED I & II SNOVET SNOMED III SNOMED RT SNOMED CT 1965 2000 IHTSDO

10 Development history SNOP Morphologies SNOMED Morphologies, Etiologies, Locations SNOVET Same structure as SNOMED Mix of existing SNOMED, additional veterinary content SNOMED III Disorders, Morphology, Living organisms, social context Veterinary content re-integrated SNOMED RT Logic based approach to SNOMED. Axes became hierarchies. Most significantly, the poly-hierarchic approach to classification. SNOMED CT SNOMED RT on steroids. Post merger with CTv3.

11 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

12 Solution to synonymy Obvious duplicates in AAHA draft list: HYPERGLYCEMIA, BLOOD GLUCOSE INCREASED AAHA Category = Hematology, Lymphatic, Endocrine HYPERGLYCEMIA, BLOOD GLUCOSE INCREASED 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)

13 Local Synonyms It is POSSIBLE to allow practitioners to add their own favorite description of a concept. Analysis / transmission by conceptID.

14 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.

15 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.

16 Functional Subsets All of SNOMED Vet Subset Cardiovascular disease subset Algorithm Cardiovascular Diseases Intersection = Veterinary Cardiovascular Diseases

17 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.

18 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

19 Subsets All veterinary contentRoot Veterinary Subset (large) 100 k ? BacteriaLiving organism automated subset 8500 concepts Abnormal MorphologiesBody structure automated subset 4000 concepts Respiratory FindingsFindings/disorders automated subset 850 SeveritiesAutomated from qualifiers5

20 AAHA Subset(s) SNOMED then remove hierarchies that are NOT of interest. Someone has to decide whats not of interest Someone familiar with SNOMED Someone with domain knowledge Desired functionality We think its 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.

21 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

22 What were 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

23 Mapping (why we didnt just map AAHAs 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)

24 Mapping 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

25 AAHA terminology development There is no final version Walk dont run No syntax (post-coordination) just yet Breadth first, depth later

26 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.

27 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.

28 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

29 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

30 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.

31 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.

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