SNOMED CT Family of Languages Dr Linda Bird, IHTSDO Implementation Specialist

SNOMED CT Family of Languages We need a consistent ‘family of languages’ that supports SNOMED CT related activities, including: ▪Defining postcoordinated clinical meanings ▪Binding SNOMED CT to information models ▪Defining intensional reference sets ▪Querying SNOMED CT ▪Representing the SNOMED CT concept model

SNOMED CT Languages ▪Compositional Grammar ▪To define a SNOMED CT expression ▪Expression Constraint Language ▪To constrain the set of possible concepts or expressions ▪Query Language ▪To query over SNOMED CT content ▪Template Languages ▪To incorporate ‘slots’ to be filled at a later time

Compositional Grammar To express a clinical idea using a SNOMED CT expression ▪Expression: A structured combination of one or more concept identifiers used to express a clinical idea ▪Precoordinated expression: An expression containing a single concept identifier ▪Postcoordinated expression: An expression containing two or more concept identifiers ▪Use Cases: ▪Expressions in health records ▪Expressions in messages ▪Precoordinated concept definitions ▪Expression associations with LOINC

Compositional Grammar

▪Examples: ▪ |hip joint structure|: |laterality| = |left| ▪ |prosthetic arthroplasty of the hip|: |procedure site| = ( |hip joint structure|: |laterality| = |left|) ▪ |amoxicillin capsule|: { |has active ingredient| = |amoxicillin trihydrate|, |has reference basis of strength| = |amoxicillin| |strength magnitude equal to| = #500, |strength unit| = |mg|} |trade name| = “AMOXIL” ▪<<< |diabetes mellitus|: |finding site| = |endocrine system|

Compositional Grammar ▪Specification and Implementation Guide ▪Introduction ▪Use Cases ▪Requirements ▪Logical Model ▪Syntax Specification ▪Examples ▪Implementation Considerations ▪Appendix A: Concept Definition & Expression Relationship Statements ▪Backwardly compatible with previous specification ▪Two significant enhancements ▪Concrete values ▪Definition status ▪Community Review closes 14 th November

Expression Constraint Language * To constrain the set of possible concepts or expressions ▪Expression Constraint: A computable rule that can be used to define a set of concepts or expressions ▪Use cases: ▪Constrain content of a particular data element in an EHR ▪Create a machine processable query over SNOMED CT concepts ▪Define an intensional reference set ▪Define a range constraint in the SNOMED CT concept model * Draft language available late 2014

Expression Constraint Language

To constrain the set of possible expressions ▪Examples: ▪^ |problem list reference set| ▪<< |procedure|: |finding site| = << |heart structure| ▪< |disorder of lung| AND ! ^ |cardiology reference set| ▪<< |clinical finding| : |associated morphology| = << |infarct| OR |due to| = << |myocardial infarction| ▪< |pharmaceutical / biologic product|: [3..*] |has active ingredient| = < |substance|

Expression Constraint Language Specification and Implementation Guide ▪Currently in review by Languages Advisory Group ▪Committee and community review will follow

Query Language * To query over SNOMED CT content ▪Use cases: ▪Querying SNOMED CT content ▪Defining intensional reference sets ▪Querying patient data ▪Binding SNOMED CT to ICD-11 linearizations ▪Filter Keywords: ▪version ▪effectiveTime ▪active ▪moduleId ▪definitionStatus (concept) ▪characteristicType (relationship) ▪member (reference set)  languageCode (description)  typeId (description)  term (description)  caseSignificanceId (description)  languageRefSet  preferredTerm  fullySpecifiedName  acceptableTerm * Draft language available late 2014

Query Language To query over SNOMED CT content ▪Examples: ▪<< |disease| {{ term = “.* heart.*” }} ▪<< |disease| {{ preferredTerm = “.* heart.*” }} ▪<< |disease| {{ preferredTerm = “.* heart.*”, languageRefSet = |GB English| }} ▪<< |clinical finding| {{ definitionStatus = |defined| }} ▪<< |SNOMED CT concept| {{ version = }} ▪^ |procedure frequency refset| {{ member |frequency| > #100 }}

Template Language * To incorporate slots to be filled at a later time ▪Use cases: ▪Defining reusable patterns for pre- or post-coordination ▪Defining information model constraints ▪Transforming between equivalent information models ▪Expression Template Examples: ▪[[ $diagnosis]]: |finding site| = [[$bodySite]] ▪[[ << |disease| ]]: |finding site| = [[ < |anatomical structure | ]] ▪Expression Constraint Template Example: ▪<< [[$procedure]] * Draft language available early 2015

Questions and Discussion