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When implementing SNOMED CT there is often a need to link SNOMED CT to other code systems. Examples of practical uses of a map are described in the table below:

Integrating local codes and SNOMED CT
Using a library of clinical phrases as an interface terminologyIn some cases a library of clinical phrases, that is not part of SNOMED CT, may be used as the interface terminology for a particular data entry scenario. In this situation a map from the library of clinical phrases to SNOMED CT can support use of SNOMED CT for storage, analytics, and communication, while retaining the clinical phrases for presentation to the user. 

Communication of clinical data between organizations

Messages and communication services are a means of exchanging data and thus enable effective and efficient sharing of information among healthcare professionals and between patients and providers. SNOMED CT is important for communication because it serves as a semantic foundation for the meaning expressed in a message. Therefore SNOMED CT can ensure consistent and accurate representation of the information communicated, and support the correct interpretation of the clinical information within a message.

Mappings between SNOMED CT concepts and data elements within a communication or messaging specification may be developed and included in an extension to facilitate unambiguous communication of processable meaning across systems and organizations.

Migration to SNOMED CT

A map between the legacy codes from the original system and the corresponding SNOMED CT components can be developed to retain accessibility of legacy data as part of a system that uses SNOMED CT

Integrating statistical classification systems and SNOMED CT

Statistical analysis of SNOMED CT encoded data Clinical information recorded using SNOMED CT may include data that is relevant to reports, statistics, or billing claims which needs to be encoded using a specific code system or a statistical classification, such as ICD-10. Mapping from SNOMED CT to the relevant code system will allow information to be used for those purposes, and at the same time, minimize the requirement for additional manual data entry. Mapping also supports the idea that clinical information collected at the point of care should be represented in a semantically rich way that allows it to be retrieved and processed for a range of different purposes. 

Meaning-based analysis of statistical data

Maps from other code systems or statistical classifications to SNOMED CT may also be included in an extension. For example, in situations where data is originally captured using a specific code system or statistical classification, but a map to SNOMED CT is required to enable analysis which takes advantage of the features of SNOMED CT, for example selective retrieval of data based on the defining characteristics of the concepts. For more information on this topic, please refer to section SNOMED CT Analytic Techniques, in Data Analytics with SNOMED CT.

Key Steps

In section 5 Key Steps we explain the full set of steps for producing any extension. However, not all of these steps are required for all purposes. If producing an extension for the purpose of representing a map between SNOMED CT and other code systems, the following key steps are of particular relevance: 


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