Purpose

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

Data structure

A is an Integer - Integer - - - - . 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 ( ) which is not used for this type of map.

An follows the same pattern but adds one additional column. It is an Integer - Integer - - - - - and this pattern is currently used for maps to ICD-10. Its structure is shown in the following table, and includes the .

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

Map Group, Priority and Rules

Values for are allocated on a sequential basis (for each and combination) during authoring starting at 1. However, distributed are not necessarily sequential, as some may be created and removed during a mapping process between releases. For maps where each only maps to at most one of a group of alternate , 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 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 . 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 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 ICD-10 Mapping Technical Guide

Mapping Rule Specifications

The specific grammar and content of the rules for resolving complex mapping cases depends on the nature of the 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 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 are included in the ICD-10 Mapping Technical Guide.

Metadata

The following metadata supports this :

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

  900000000000454005 |Foundation metadata concept|
		900000000000455006 |Reference set|
				447250001 |Complex map from SNOMED CT type reference set|
				609331003 |Extended map from SNOMED CT type reference set|

Descriptor Templates

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

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

refsetId	referencedComponentId (Referenced component)	attributeDescription (Attribute description)	attributeType (Attribute type)	attributeOrder (Attribute order)
				0
				1
				2
				3
				4
				5
				6

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

refsetId	referencedComponentId (Referenced component)	attributeDescription (Attribute description)	attributeType (Attribute type)	attributeOrder (Attribute order)
				0
				1
				2
				3
				4
				5
				6
				7

Example Data

Sample Content from an Extended Map from SNOMED CT Reference Set