SNOMED CT® Release Format 1 (RF1) Guide - ihtsdo

• as a combination of codes;
• a choice of several possible mappings consisting of one or more codes.
• Current support is for a single Target Code, multiple Target Codes, and a choice of single or multiple
Target Codes.
3. The accuracy of mapping:
• A target mapping may represent a Concept:
• precisely.
• imprecisely:
• target more specific than source;
• target less specific than source;
• imprecise but neither more nor less specific.
• An indication of accuracy can be associated with each Cross Map.
Practical requirements for mapping from SNOMED CT to other terminologies or classifications (Target
Schemes) are not limited to mapping single Concepts in SNOMED CT to single Target Codes. The more
general problem is to map information in a patient record that has been encoded using SNOMED CT Concepts
into an appropriate Target Code or set of Target Codes.
It will be impossible to map some Concepts to any Target Codes in some Target Schemes.
A SNOMED CT Concept may be unmappable for one of several reasons:
• It expresses a concept that is outside the domain covered by the Target Scheme
• It is insufficiently detailed to provide a meaningful cross mapping:
• In this case a mappable code may be found by refining the SNOMED CT Concept (i.e. selecting an |
is a | descendant).
• It is too detailed and information will be lost in the mapping:
• If this loss of detail is unimportant with respect to the purpose of the mapping, it is possible to map the
most proximal more generalized Concept that is mappable, or to create the map but indicate that the
match is not 1:1.
• It is inappropriate to map the concept:
Release File Formats | 117
• For example, disorders that do not apply to humans need not be mapped to an ICD-9 code.
© 2002-2012 International Health Terminology Standards Development Organisation CVR #: 30363434