SNOMED Clinical Terms - Introduction


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Anne Casey RN MSc FRCN
Editor, Paediatric Nursing
Royal College of Nursing Adviser on Information Standards
Clinical Domain Lead, NHS Information Standards Board for Health and Social Care
(15/10/08, SNOMED Workshop)

Published in: Health & Medicine, Business
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SNOMED Clinical Terms - Introduction

  1. 1. SNOMED Clinical Terms - Introduction Anne Casey RN, MSc FRCN Editor Paediatric Nursing Adviser in Informatics Standards to the Royal College of Nursing Clinical Domain Lead, NHS (England) Information Standards Board for Health and Social Care
  2. 2. Overview Requirements summary SNOMED CT – Basics – Relationships to other terminologies Getting involved – IHTSDO governance – Working groups ‘Local work towards a national / international standard’ Implementation considerations Discussion
  3. 3. SNOMED CT documents at • SNOMED Clinical terms Fundamentals ppt • IHTSDO Modeling style guide overview • SNOMED Clinical Terms® User Guide • Content inclusion principles and practice • Style guides: anatomy, clinical findings, procedures etc • Technical reference guide
  4. 4. eHealth opportunities – Multi-disciplinary, cross sector records and communications – Ways of recording /displaying information not possible in paper records (helpful record structures) – Ways of aggregating individual level data to support population analyses – Content standards for clinical elements of electronic records (that support good standards of treatment and care)
  5. 5. Context ICT that supports clinical decision making and the work of clinicians Future of cross sector working, team based care, single shared record, (consumer-owned) Current ‘mixed economy’ for healthcare records – separate records for each profession – single patient record with different sections for each profession – single patient record – Patient/client held record
  6. 6. Content Requirement patient terminology? nursing terminology medical terminology laboratory terminology physiotherapy terminology, dietetics, …. drugs, equipment terminologies social care terminology …….
  7. 7. Requirements to support interoperability in an eHealth world Standard, multi professional terminology with characteristics that support data entry, retrieval, links to decision support, messaging, maps to other terminologies / classifications, translation etc.
  8. 8. SNOMED Clinical Terms….. …a terminological resource that can be implemented in software applications to represent clinically relevant information comprehensive (>350,000 concepts) multi-disciplinary coverage but discipline neutral structured to support data entry, retrieval, maps etc Maintained and updated based on user input and quality review
  9. 9. Requirements drive the design, development and maintenance of SCT Requirements related to electronic patient records – Support for effective delivery of high quality healthcare to individuals and to populations General requirements for a terminology Implementation and migration requirements Requirements related to the intended user communities – International, multilingual applicability – Support for particular local requirements National and strategic priorities
  10. 10. General Properties Interface - supporting data entry – broad coverage, granular, synonyms, pre-coordinated terms, ‘natural language’, translations Reference - supporting data retrieval – Subtype hierarchies that allow items to be aggregated – Defining relationships that allow computation of equivalence and subsumption – … and aspects of the terminology that manage context
  11. 11. Relationship between SNOMED CT and other terminological systems Different terminologies have features suited to their different purposes, such as... clinical definitions – e.g. pyrexia in an immunocompromised patient = 37.5°C ‘knowledge’ relationships – e.g. contraindications for use of aspirin classification concepts – e.g. other procedure simple coding scheme for use on paper grouping / organisation of terms for particular purposes – e.g. a list of investigations to be done for pyrexial patient
  12. 12. SNOMED CT has a specific set of purposes – it doesn’t do what some other ‘terminologies’ do.. Example 1. ICF ..describes body functions and structures, activities and participation - used to understand and measure health outcomes Example 2. Nursing terminologies such as NANDA diagnoses the description of nursing for practice, education and research; may include knowledge that supports clinical reasoning (e.g. defining characteristics of NANDA diagnoses)
  13. 13. Basic Elements of SNOMED CT Concepts • The basic units of SNOMED CT Descriptions • These relate terms that name the concepts to the concepts themselves. Each concept has at least two Descriptions. Relationships • Relationships are the connections between concepts in SNOMED CT. Attributes / qualifiers - properties of concepts Formal concept definitions - relationships that define the meaning of a concept relative to other concepts Tables – SCT distributed as flat files for incorporation into software (terminology server or direct to EPR ‘catalogue’)
  14. 14. Concepts Represent distinct clinical meanings Are identified by a unique numeric identifier (Concept ID) that never changes and a unique human readable name (Fully Specified Name) Are associated with a set of relationships (the “logical definition”) and two or more descriptions
  15. 15. Descriptions Concept descriptions relate the terms or names of a SNOMED CT concept to the concept itself. “Term” in this context means a phrase used to name a concept. A single description associates a single term with a single Concept ID. Descriptions are an important interface property because they give end users the flexibility to use terms that they are familiar with The Concept ID ties terms with the same meaning together to aid consistent interpretation and retrieval.
  16. 16. Description types Preferred Term • The most common word or phrase used by clinicians to name a concept The Fully Specified Name • Provides an unambiguous way to name a concept Synonyms • The rest of the names that may be used for a concept
  17. 17. A SNOMED CT Concept Some of the descriptions associated with ConceptID 22298006: • Fully Specified Name: Myocardial infarction (disorder) DescriptionID 751689013 • Preferred term: Myocardial infarction DescriptionID 37436014 • Synonym: Cardiac infarction DescriptionID 37442013 • Synonym: Heart attack DescriptionID 37443015 • Synonym: Infarction of heart DescriptionID 37441018
  18. 18. FSNs reduce ambiguity Dressing (oneself) Dressing (observable entity) parent – personal care activity Dressing (e.g. a bandage) Dressing, device (physical object) Dressing (assisting the Dressing patient (procedure) person to dress) Dressing (of wound) Dressing of wound (procedure)
  19. 19. The problem with words and meaning What is a “pyogenic granuloma?” • Pyogenic = pus forming • Granuloma = a collection of inflammatory cells of a particular type But • Pyogenic granuloma = a benign tumor of small blood vessels of the skin • It is neither pyogenic nor a granuloma. Combinations are frequently very different from the sum of their parts
  20. 20. SNOMED is not the “language police” SNOMED CT seeks to • Establish how language is used by clinicians • To represent meaning as faithfully as possible. SNOMED CT declares what it thinks a phrase means • To reflect current usage • To minimise ambiguity • Not to shape or control the way a phrase is used If you want someone to demand that clinicians change what they call “pyogenic granuloma” • That may be someone else’s job • It’s not something SNOMED CT is trying to do
  21. 21. Top-level hierarchies 1. Clinical finding 2. Procedure 3. Observable entity 4. Body structure 5. Organism 6. Substance 7. Pharmaceutical/biologic product 8. Specimen 9. Physical object 10. Physical force 11. Events 12. Environment or geographical Location 13. Social context 14. Situation with explicit context 15. Staging and scales 16. Qualifier value 17. Special concept 18. Linkage concept 19. Record artifact 20. SNOMED-CT UK Administrative Concepts
  22. 22. Relationships The connections between concepts • Every SNOMED CT concept has at least one relationship to another concept • Relationships characterize concepts and give them their meaning • The list of relationships for a particular concept makes up the logical definition of that concept 2 types: • IS-A (sub-type/super-type) • Attribute
  23. 23. Relationships cont… ‘Is a’ relationship also known as supertype-subtype or parent child relationships A relationship is assigned only when that relationship is always known to be true (i.e there are no ‘maybes’)
  24. 24. ‘Only necessarily true’ ‘Pain in calf’ is included in SNOMED CT as it is a concept agreed to be relevant in practice It is also possible to say which calf, how severe, how long etc but these are NOT definitional of the specific phrase ‘pain in calf’
  25. 25. Attribute Relationships Characterize and specify concepts An example of an attribute is FINDING-SITE, which is used to further specify Disease concepts - e.g. part of the logical definition of the concept Pneumonia in SNOMED CT is: - Concept = Pneumonia - Attribute = FINDING-SITE - Value of attribute = Lung structure
  26. 26. ‘Context’ Context refers to the effects of embedding a concept code in a clinical statement A code is embedded in a clinical statement when it is used in a clinical record Embedding a code in a clinical statement Adds information – Date of finding or action – Author, performer, etc. May also elaborate its meaning in one of several ways – Subtype qualification – Axis modification – Affirmation or Negation – Combination
  27. 27. Context: Representation Context can be represented in various ways Pre-coordination of SNOMED CT concepts – Example 160303001 Family History of diabetes mellitus Post-coordination of SNOMED CT concepts that together express a more specific concept – Example 57177007+(246090004=73211009 ) Family history + (Assoc. finding = Diabetes mellitus) Structures and attributes specific to a proprietary data model or a standard reference model – Examples from HL7 RIM ActRelationshipclass moodCodeattribute
  28. 28. Other things – RefSets: Reference Sets [aka Subsets] including language RefSets Extensions: support Realm-specific content that is not required in the international release e.g.leave granted under the Mental Health Act 1983 (England and Wales) Cross Maps: linking SNOMED CT to other terminologies mechanisms for developing and maintaining shared resources
  29. 29. Reference Set mechanism ‘The effective usage of SNOMED CT requires a way to refer to sets of components that are appropriate for a specific use case’ This ‘referring to’ is achieved by the SNOMED CT Reference Set mechanism [SNOMED CT Reference Sets at] NOTE: The preferred term is Reference Set (RefSet), as Subset is potentially misleading (and the RefSet mechanism does more than the original SNOMED Subset mechanism).
  30. 30. Terminology Infrastructure IHTSDO Board SNOMED CT Committees international feedback Working groups SNOMED CT National terminology Service + national subsets National working groups & extensions System suppliers SNOMED CT In Use Other Terminologies
  31. 31. Nursing Special Interest Group Reports to IHTSDO Content Committee Objectives: – ensure adequate content to support nursing practice – Identify and prioritize new content inclusion – Develop partnerships and relationships with (nursing) system suppliers & other specialty organization – Provide guidance about the use of SNOMED CT in Nursing practice Open membership: ICN, ANA, RCN, nurses from IT, clinical practice, education
  32. 32. Examples of Nursing SIG projects Working with SNOMED CT – basic guide Education, advice and counselling Representing assessment scales in SNOMED CT Lines, catheters, cannulae – with anaesthesia
  33. 33. Education Special Interest Group Reports to Quality Committee Open participation Issues – conflict of interest declaration – IPR issues – volunteer v funded work – Consensus v evidence based – use what’s out there; provide back to others; evaluate and refine
  34. 34. Education SIG priorities SNOMED Editors’ curriculum – Specialist additions: mappers, translators – Competency framework and certification – Informs tools specification (safe place to practise!) SNOMED Implementers’ curriculum [educational needs of clinical and other communities] NB curriculum v syllabus or standard course content
  35. 35. SNOMED CT Content development Expert committee System content SNOMED CT developer End user
  36. 36. Contributions to content development and quality review Specialty lists - making implementation easier: radiology, general practice, nursing Encoding of national (international?) standards – Assessment instruments: Glasgow coma scale, Barthel index, – Standard structured records / clinical datasets: diabetic retinopathy screening record, national renal dataset – Archetype repositories
  37. 37. Wouldn’t it be good if.. Clinical guidelines and accompanying audit datasets used consistent, SNOMED aligned terminology
  38. 38. Local work… Emergency Department diagnosis recording using SNOMED ED Subset v national data dictionary term list 450 terms v 22 terms (including diagnosis not classifiable) PRE: 28.9% of 18,457 records had no recorded diagnosis. POST: 7.7% of 18,798 records had no recorded diagnosis Lessons learnt: gaps in subset (770); anatomy post co-ordinated? Tony Shannon, Consultant in Emergency Medicine, Leeds Teaching Hospital & Clinical Lead, Clinical Content Service, NHS Connecting for Health
  39. 39. SNOMED CT – a terminological resource ‘The benefit of recording information in a standard terminology such as SNOMED CT is linked to the benefits of the electronic care record and the benefits of recording clinical information in a structured form’ SNOMED CT - the language of the NHS Care Records Service.
  40. 40. Content standards A ‘terminological resource’ = Many ways to say the same thing SNOMED CT 366,000 Coded Concepts 993,000 Terms For patient safety and 1.46M Relationships good communication we need standards for record and message content including restricted sets of SNOMED terms/codes
  41. 41. Implementation requires evolution of…. SNOMED CT – usable components work Systems Users In the context of ACTUAL requirements for coded data (also evolving)
  42. 42. Implementation of SNOMED CT in clinical systems ‘Level 2 systems have internal support for SNOMED CT using both pre and post co-ordinated content….. most fully exploit the benefits of using SCT. For the most part these systems do not exist and will require the development of new user interfaces, database information and system interfaces.’ [Implementing SNOMED CT within national electronic record solutions – CHIRAD Health Informatics, – Big Issue]
  43. 43. Users? 1. Clinicians Administrative and secretarial staff Secondary users of data: researchers, auditors, coders .. 2. System content developers including expert clinicians 3. Terminology developers
  44. 44. Migration of clinician users… …from unstructured, non …to structured, standard standard, narrative records records and messages …from vague, ambiguous, standard, defined, local terminology and locally evidence based adapted clinical tools terminologies and tools ...from paper records …to ICT that supports clinical workflow, decision making, recording and communication (and has standard terminology for interoperability)