SNOMEDSNOMEDCore StructuresCore Structures

NAHLNNAHLNJanuary 2005January 2005

Las Vegas, NVLas Vegas, NV

SNOMED CoreSNOMED Core

SNOMED CoreSNOMED Core

Concepts Table Each row in this table represents a medical concept.

Descriptions Table Each row in this table specifies a term that can be applied to describe a

single clinical concept.Relationships Table

Each row in this table specifies a relationship between two clinical concepts. The nature of each relationship is represented using a special kind of clinical concept.

SNOMED CoreSNOMED Core

A concept is described by the term (string) in 2-n descriptions

At least the Fully Specified Name (FSN) + Preferred Term

Each description refers to (only) 1 concept.

SNOMED CoreSNOMED Core

A concept is the source of 1-n relationships (except the root concept).A concept is the target of 1-n relationships.A concept represents the type of relationship.A relationship refers to 3 concepts: a source, a target, and a relationship type.

Terminology of TerminologyTerminology of TerminologyConceptConcept embodiment of a particular meaningembodiment of a particular meaning Really a “virtual” element in the systemReally a “virtual” element in the system The string in concepts table is a member of the The string in concepts table is a member of the

related list of descriptions.related list of descriptions.DescriptionDescription Any string used to represent a conceptAny string used to represent a conceptRelationshipRelationship (in SNOMED) an object – attribute – value triple (in SNOMED) an object – attribute – value triple

connecting two concepts through an attributeconnecting two concepts through an attribute Relationships in SNOMED are explicit rather than Relationships in SNOMED are explicit rather than

implicit (as was the case in SNOMED III)implicit (as was the case in SNOMED III)

Concepts Table FieldsConcepts Table FieldsKey FieldsConceptId The unique SNOMED Clinical Terms Identifier for this

Concept.

Data FieldsConceptStatus The status of a Concept indicates whether it is in active use

and, if not, indicates the reason for withdrawal from current use.

FullySpecifiedName A unique phrase that describes a Concept in a way that is intended to be unambiguous.

CTV3ID The Read Code for this Concept.

SNOMEDID The current SNOMED identifier for this Concept.

IsPrimitive Indicates whether a Concept is Primitive or Fully defined by its current set of Defining characteristics.

Relationships TableRelationships TableKey FieldsRelationshipId The unique SNOMED CT Identifier of this Relationship.

Data FieldsConceptId1 The unique SNOMED CT Identifier of the Concept which is the

source of this Relationship.

RelationshipType The unique SNOMED CT Identifier of the Concept which represents the type of relationship between the related Concepts.

ConceptId2 The unique SNOMED CT Identifier of the Concept which is the target of this Relationship.

CharacteristicType An indication of whether a Relationship specifies a defining characteristic of the source Concept or a possible qualifying characteristic of that Concept.

Refinability An indication of whether it is possible to refine the target Concept when this relationship is used as a template for clinical data entry.

RelationshipGroup An integer value that links together Relationships which are part of a logically associated Relationship group.

Concept -> RelationshipConcept -> Relationship

72704001727040011166760081166760087162000071620000

Concept IDConcept IDRelationship IDRelationship IDConcept IDConcept ID

Relationship Table

Fracture (morphology)Fracture (morphology)M-12000M-120007270400172704001

Associated MorphologyAssociated MorphologyG-C504G-C504116676008116676008

Fracture of FemurFracture of FemurDD-13100DD-131007162000071620000

Concept NameConcept NameSNOMED IDSNOMED IDSCT IDSCT ID

Concepts Table

Relationship GroupsRelationship Groups

A mechanism for retaining relationships A mechanism for retaining relationships between definition “parts”between definition “parts”Avoids relationship “nesting”Avoids relationship “nesting”

Relationship GroupsRelationship Groups

Is a Contusion to heartIs a Open wound of trunkGroup 1

Associated morphology Open woundFinding site Thoracic structure

Group 2Associated morphology Contusion - lesionFinding site Heart structure

Contusion to heart with open wound into thorax

Relationship and Characteristic Relationship and Characteristic TypesTypes

RelationshipsType field is the concept code that RelationshipsType field is the concept code that specifies the attribute in the triple.specifies the attribute in the triple.CharacteristicType tells whether the relationship CharacteristicType tells whether the relationship is:is: Defining (0)Defining (0) Qualifying (1)Qualifying (1) Historical (2 – history table only)Historical (2 – history table only) Additional (3 – for facts that cannot be defining)Additional (3 – for facts that cannot be defining)

Relationships - RefineabilityRelationships - Refineability

Indicates whether the target concept can Indicates whether the target concept can be further refined when the relationship is be further refined when the relationship is used in a clinical templateused in a clinical template Not refineable (0)Not refineable (0) Optional (2)Optional (2) Mandatory (3)Mandatory (3)

Not our problem just now.Not our problem just now.

Descriptions TableDescriptions TableKey FieldsDescriptionId The unique SNOMED CT Identifier for this Description.

Data FieldsDescriptionStatus The status of a Description indicates whether it is in active use

and, if not, indicates the reason for withdrawal from current use.

ConceptId The unique SNOMED CT Identifier of the associated Concept. (Foreign key to Concepts Table).

Term The text of a Term used to describe the associated Concept.

InitialCapitalStatus An indication of whether the capitalization status of the first character of the Term is significant.

DescriptionType An indication of whether the Term is the Fully Specified Name, Preferred Term or Synonym for the Concept to which this Description applies.

LanguageCode An indication of a Language or Dialect in which this Description is valid. The language or dialect subset ultimately defines the descriptions for each concept.

Concepts -> DescriptionsConcepts -> Descriptions

233604007233604007 D2-0007FD2-0007F Pneumonia (concept)Pneumonia (concept)

22Synonym In Local ExtensionSynonym In Local Extension233604007233604007xxxxxxxxxxxxzzzzzz11x11x

22Synonym in NAHLN ExtensionSynonym in NAHLN Extension233604007233604007xxxxxxxxxxxxyyyyyy11x11x22Synonym in CoreSynonym in Core233604007233604007xxxxxx01xxxxxxx01x

11PneumoniaPneumonia23360400723360400762181001762181001733Pneumonia (Disorder)Pneumonia (Disorder)233604007233604007350049016350049016

1 = “preferred” description (term) – preferred by SNOMED, perhaps not your users2 = synonym (alternate)3 = fully specified name

Component History TableComponent History Table(future use)(future use)

Key FieldsKey Fields

ComponentIDComponentID The unique SNOMED CT Identifier for the changed Component.

ReleaseVersionReleaseVersion The version of SNOMED CT in which this change was made.

Data FieldsData Fields

ChangeTypeChangeType An indication of the nature of the change.

StatusStatus The status of this Component after the change.

ReasonReason An optional text Description of the reason for the change.

Historical RelationshipsHistorical RelationshipsKey FieldsRelationshipId The unique SNOMED CT Identifier of this Relationship.

Data FieldsConceptId1 The unique SNOMED CT Identifier of the Concept which is the

source of this Relationship.

RelationshipType The unique SNOMED CT Identifier of the Concept which represents the type of relationship between the related Concepts.

ConceptId2 The unique SNOMED CT Identifier of the Concept which is the target of this Relationship.

CharacteristicType An indication of whether a Relationship specifies a defining characteristic of the source Concept or a possible qualifying characteristic of that Concept.

Refinability An indication of whether it is possible to refine the target Concept when this relationship is used as a template for clinical data entry.

RelationshipGroup An integer value that links together Relationships which are part of a logically associated Relationship group.

Historical RelationshipsHistorical Relationships

Allowed attribute values SAME AS (redundant) MAYBE A (ambiguous - 2 or more) REPLACED BY (major changes) WAS A (IS A no longer valid) MOVED TO (namespace change) MOVED FROM (namespace change)

SCTIDSCTID

The SCTID data type is a 64-bit integer, which is subject to the following constraints:

Only positive integer values are permitted. The minimum permitted value is 100,000 (6 digits) The maximum permitted value is

999,999,999,999,999,999 (18-digits). As result of rules for the partition-identifier and check-

digit, many integers within this range are not valid SCTIDs.

SCTIDSCTIDThe SCTID does not contain semantic information related to the meaning of a concept or termIt does however have a structure that is designed to allow different types of terminological components to be recognized.

The nature of a component can be derived from the table in which a component is distributed.

Partitioning the SCTID avoids reuse of the same identifier for a different type of component – thus avoiding ambiguity.

This also allows the nature of the identifier to be recognized when stored in a record or transferred in a message.

SCTIDSCTID

SCTID for centrally distributed component.

SCTIDSCTID

SCTID for a component in an extension.

SCTID Partition ValuesSCTID Partition Values0000 A conceptA concept

0101 A descriptionA description

0202 A relationshipA relationship

0303 A subsetA subset

0404 A Cross Map setA Cross Map set

0505 A Cross Map targetA Cross Map target

1010 A concept in an extensionA concept in an extension

1111 A description in an extensionA description in an extension

1212 A relationship in an extensionA relationship in an extension

1313 A subset in an extensionA subset in an extension

1414 A Cross Map set in an extensionA Cross Map set in an extension

1515 A Cross Map target in an extensionA Cross Map target in an extension

IndexesIndexes

Excluded wordsExcluded wordsDescription word keyDescription word keyConcept word keyConcept word keyDescription dual keyDescription dual keyConcept dual keyConcept dual key