• Simple Map from SNOMED CT Reference Set

• Simple Map to SNOMED CT Reference Set

• Complex and Extended Map from SNOMED CT Reference Sets

• Map to SNOMED CT with Correlation and Origin Reference Set

Purpose

A 1193544002 |Simple map with correlation from SNOMED CT to SNOMED CT type reference set (foundation metadata concept)| supports the representation of simple maps from SNOMED CT concepts to SNOMED CT concepts. No constraints are put on the number of SNOMED CT concepts to which each SNOMED CT concept is mapped.

Data structure

A |Simple map with correlation from SNOMED CT to SNOMED CT type reference set (foundation metadata concept)| is a Component - Component reference set used to represent maps from SNOMED CT concepts to SNOMED CT concepts. Its structure is shown in the following table.

Simple map with correlation from SNOMED CT to SNOMED CT type reference set - Data structure

The following metadata hierarchy supports this reference set:

Simple map with correlation to |SNOMED CT type reference set (foundation metadata concept)| in the Metadata Hierarchy

The tables below show the descriptors that define examples of reference sets that follow the pattern.

Refset Descriptor rows for Simple Map with correlation from SNOMED CT to SNOMED CT Reference Set

Sample Content from a Simple Map with correlation from SNOMED CT to SNOMED CT Reference Set

Purpose

A 1193543008 |Simple map with correlation to SNOMED CT type reference set (foundation metadata concept)| supports the representation of simple maps from values in other code systems to SNOMED CT concepts. No constraints are put on the number of SNOMED CT concepts to which a particular code is mapped.

Data structure

A 1193543008 |Simple map with correlation to SNOMED CT type reference set (foundation metadata concept)| is a String - Component reference set used to represent maps from codes in another terminology, classification or code system to SNOMED CT concepts. Its structure is shown in the following table.

Simple map with correlation to SNOMED CT type reference set - Data structure

The following metadata hierarchy supports this reference set:

Simple map with correlation to SNOMED CT type reference set (foundation metadata concept)| in the Metadata Hierarchy

The tables below show the descriptors that define examples of reference sets that follow the pattern.

Refset Descriptor rows for Simple map with correlation to SNOMED CT type reference set

Sample Content from a Simple Map to SNOMED CT Reference Set

Purpose

A 900000000000496009 |Simple map from SNOMED CT reference set| supports the representation of simple maps from SNOMED CT concepts to values in other code systems. No constraints are put on the number of coding schemes supported, the number of codes within a particular scheme mapped to by a single SNOMED CT concept or the number of SNOMED CT concepts mapping to a particular code. However, this type of reference set is usually only appropriate where there is a close "one-to-one" mapping between SNOMED CT concepts and coded values in another code system.

Data structure

A 900000000000496009 |Simple map from SNOMED CT reference set| is a String Reference Set used to represent maps from SNOMED CT concepts to codes in another terminology, classification or code system. Its structure is shown in the following table.

Table: Simple map from SNOMED CT reference set - Data structure

The following metadata hierarchy supports this reference set:

Simple Map from SNOMED CT Reference Sets in the Metadata Hierarchy

The tables below show the descriptors that define examples of reference sets that follow the pattern.

Refset Descriptor rows

Sample Content from a Simple Map From SNOMED CT Reference Set

Purpose

A 1193542003 |Simple map with correlation from SNOMED CT type reference set| supports the representation of simple maps from SNOMED CT concepts to values in other code systems. No constraints are put on the number of codes mapped from a single SNOMED CT concept.

Data structure

A 1193542003 |Simple map with correlation from SNOMED CT type reference set| is a String - Component reference set used to represent maps from SNOMED CT concepts to codes in another terminology, classification or code system, with the correlation between these codes. Its structure is shown in the following table.

Simple map with correlation from SNOMED CT type reference set - Data structure

The following metadata hierarchy supports this reference set:

Simple map with correlation from SNOMED CT type reference sets in the Metadata Hierarchy

The tables below show the descriptors that define examples of reference sets that follow the pattern.

Refset Descriptor rows for Simple map with correlation from SNOMED CT type reference set

Sample Content from a Simple map with correlation from SNOMED CT type reference set

Purpose

A 1187636009 |Simple map to SNOMED CT type reference set| supports the representation of simple maps from values in other code systems to SNOMED CT concepts. No constraints are put on the number of SNOMED CT concepts mapping to by a particular code. However, this type of reference set is usually only appropriate where there is a close "one-to-one" mapping between the coded values in another code system and SNOMED CT concepts.

Data structure

A 1187636009 | Simple map to SNOMED CT type reference set| is a String Reference Set used to represent maps from codes in another terminology, classification or code system to SNOMED CT concepts. Its structure is shown in the following table.

Simple map to SNOMED CT reference set - Data structure

The following metadata hierarchy supports this reference set:

Simple Map to SNOMED CT Reference Sets in the Metadata Hierarchy

The tables below show the descriptors that define examples of reference sets that follow the pattern.

Refset Descriptor rows for Simple map to SNOMED CT type reference set

Sample Content from a Simple Map to SNOMED CT Reference Set

Purpose

The 705111002 |Map to SNOMED CT with correlation and origin type reference set| is used to meet the requirements for representation of maps from codes in another code system (other-codes) to a SNOMED CT concept, where the following requirements apply.

1. A requirement to indicate the degree of correlation between the SNOMED CT concept and the other-codes.

2. A requirement to indicate whether a concept or code was added to either code system as a result of the mapping process and, in this case, to indicate in which code system the concept or code originated.

3. A requirement to represent the SNOMED CT attribute to which the other-code should be applied in order to capture the full specificity of the value represented by the other-code.

4. No requirements for mapping rules or advice to be included with each map.

Map to SNOMED CT with Correlation and Origin Reference Set - Data structure

The following metadata hierarchy supports this reference set:

Map to SNOMED CT with correlation and origin type reference set in the Metadata Hierarchy

The tables below show the descriptors that define examples of reference sets that follow the pattern.

Refset Descriptor rows for Map to SNOMED CT with correlation and origin type reference set

Sample Content from a Map to SNOMED CT with correlation and origin type reference set

Purpose

The 705109006 |Code to expression type reference set| is designed to enable associations between codes in another code system (other-codes) and SNOMED CT concepts, where the following constraints apply:

1. Some of the other-codes cannot be mapped to an individual SNOMED CT concept.

2. Licensing conditions (or other considerations) prevent addition of new SNOMED CT concepts to represent the same meaning as the other-codes.

3. The other-codes can be logically defined using the SNOMED concept model to represent the same meaning (sufficiently defined) or a similar though less specific meaning (primitive).

4. Other requirements similar for those applicable to mapping may also apply including:

   1. An indication of the degree of correlation between the other-code and the SNOMED CT expression.

   2. An indication of whether the other-code was created before any single concept representation of that meaning in SNOMED CT or whether the single concept representation in SNOMED CT predated the creation of the association.

The general approach to the above requirements is to associate each of the other-codes with a representation of the same logic based definition as would have been applied to a SNOMED CT concept with that meaning. However, since the other-code are not identified by an SCTID, the logical definition cannot be represented using defining relationships. There are two potential approaches to this, one would be to use a general purpose description logic language (e.g. OWL) and the other is to use a SNOMED CT expression to represent each definition. The is designed to support the expression-based approach.

Code to Expression Reference Set - Data structure

The following metadata hierarchy supports this reference set:

Code to Expression Reference Set in the Metadata Hierarchy

The tables below show the descriptors that define examples of reference sets that follow the pattern.

Refset Descriptor rows for a Code to Expression Reference Set

Sample Content from a Code to Expression Type Reference Set

Purpose

A 447250001 |Complex map from SNOMED CT type reference set| supports the representation of maps where each SNOMED CT concept may map to one or more codes in a target scheme. This type of reference set supports the general set of mapping data required to enable a target code to be selected at run-time from a number of alternate codes. It supports target code selection by accommodating the inclusion of machine readable rules and/or human readable advice. An 609331003 |Extended map from SNOMED CT type reference set| adds an additional field to allow the categorization of maps.

Data structure

A 447250001 |Complex map from SNOMED CT type reference set| is an Integer - Integer - String - String - String - Component reference set. The pattern is currently used for the map to ICD-9-CM. Its structure is as shown in the following table, with one exception - the table below includes an additional field (mapCategoryId) which is not used for this type of map.

An 609331003 |Extended map type reference set (foundation metadata concept)| follows the same pattern but adds one additional column. It is an Integer - Integer - String - String - String - Component - Component reference set and this pattern is currently used for maps to ICD-10. Its structure is shown in the following table, and includes the mapCategoryId.

Table: Complex and Extended map from SNOMED CT type reference sets - Data structures

Values for are allocated on a sequential basis (for each refsetId and referencedComponentId combination) during authoring starting at 1. However, distributed mapGroup are not necessarily sequential, as some mapGroup may be created and removed during a mapping process between releases. For maps where each SNOMED CT concept only maps to at most one of a group of alternate target codes, the mapGroup field are usually be set to '1'.

Values for will be allocated on a sequential basis (within each map group) starting from '1'. For maps that do not require run - time alternatives, the mapPriority field is set to '1'.

The and fields enable run-time selection (within vendor's software) from a number of alternative map records within a mapGroup. Where there are no alternatives maps these columns of the release files will be empty (zero length string). Where alternative maps exist one or both of columns will be populated where relevant information is available.

Where both fields are populated, and a vendor's system is capable of processing a machine readable rule, this should take priority over the human readable advice. Where neither field is populated, a vendor's system should allow the end-user to select the appropriate target code from the alternates.

For more details on this topic in relation to the ICD-10 maps released as part of the SNOMED CT International Edition please see the .

The specific grammar and content of the rules for resolving complex mapping cases depends on the nature of the target code system or classification. In general, each map is accompanied by a rule which is tested against other data and can be evaluated to return one of the following values:

• True - in which case the map target applies;

• False - in which case the map target does not apply;

• Indeterminate - in cases where there is insufficient accessible data to determine whether the map target applies. In this case manual resolution of the map using the map advice provided will be required.

The mapping rules assume access to a number of variables, that can be bound to appropriate attributes in the vendor's system information model. These include the age and gender of the patient and information about coexisting situations (e.g. records of other disorders, procedures or events in the same patient record).

Detailed definitions of the mapping rules used forms part of individual specifications for maps to particular target code systems and classifications. This will initially be provided separately and will accompany the release of the relevant mapping files. For example, the set of rules used for mapping to ICD-10 are included in the .

The following metadata supports this reference set:

List: Complex and Extended Map from SNOMED CT References Sets in the Metadata Hierarchy

The tables below examples of the descriptors for specific reference sets that follow the and patterns.

Table: Refset Descriptor Rows for a Complex Map from SNOMED CT Reference Set

Refset Descriptor Rows for an Extended Map from SNOMED CT type Reference Set

Sample Content from an Extended Map from SNOMED CT Reference Set