When SNOMED CT content is promoted from an extension module into a less dependent module (e.g. the international edition) to enable broader use, specific changes occur in the RF2 files of the associated SNOMED CT releases. In this section, we provide examples of how the relevant RF2 release files are changed when a concept is promoted and explain how the resulting files are used.
SNOMED CT is distributed to users using one of two main approaches:
As a SNOMED CT edition, in which the SNOMED CT extension content is combined together with the files from the International Edition (and any other dependent module)
As a SNOMED CT extension, which contains only the new content added into the extension. To deploy a SNOMED CT extension, it must be combined with the international versioned edition that it is dependent on (and any other dependent modules), and any conflicts resolved (as explained below).
The diagram below illustrates these two approaches. In each approach, 3 release file types are distributed - the , the and the . Please refer to for more information.
Please note: Delta files have been removed from the SNOMED International release package, but a Delta Generation Tool is available for those who need it. The Delta Generation Tool allows users to create their own Delta between two fixed release dates - you can find it here:
In the following sections, we illustrate how each of the Concept files would appear both before and after the promotion of the fictitious concept from the to the .
In these examples, we will assume that the was:
Created in the on 31st September 2018
Updated in the on 31st March 2020
Promoted to the on the 31st July 2020
We also assume the following dependencies:
Before promotion: The 31st March 2020 version of the National Extension is dependent on the 31st January 2020 International Edition
After promotion: The 31st September 2020 version of the National Extension is dependent on the 31st July 2020 International Edition
In the following section, we will first illustrate the changes using the SNOMED CT edition distribution method. And in the subsequent section, we will illustrate these changes using the SNOMED CT extension distribution method. In both cases, we will consider the impact to all three release file types - the , the and the -
In this section, we illustrate the changes to the release files when promoting a concept using the edition distribute method.
Concept File - Full (National Edition 20200331)
Concept File - Snapshot (National Edition 20200331)
Concept File - Snapshot (National Edition 20200931)
Concept File - Delta (National Edition 20200331)
In this section, we illustrate the changes to the release files when promoting a concept using the extension distribute method.
Concept File - Full (National Extension 20200331)
Concept File - Full (International Edition 20200131)
No rows in the International Edition reference
Concept File - Snapshot (National Extension 20200931)
Concept File - Snapshot (International Edition 20200731)
Concept File - Delta (National Extension 20200331)
Concept File - Delta (International Edition 20200131)
No rows in the International Edition reference
Concept File - Delta (National Extension 20200931)
No rows in the Extension Concept File reference
Concept File - Delta (National Extension 20200931)
20180931
1
20180931
1
20200331
1
20200731
1
20200331
1
20200731
1
20180931
1
20200331
1
20200731
1
20200331
1
20200731
1
20200331
1
20200331
1
20200731
1
20200331
1
SNOMED CT content may sometimes need to be moved from one module to another, to enable it to be published in a different edition. Moving SNOMED CT content up the module dependency chain (i.e. from a given module to a module on which it depends) is known as content promotion. This may be required to make the content accessible to a wider audience. Moving SNOMED CT content down the module dependency chain (i.e. from a given module to a module that is dependent on it) is known as content demotion. This may be required to make the content accessible to a narrower audience. In these situations, it is essential to be aware of the principles for promotion and demotion. These principles ensure the integrity and traceability of the content, in both the original module and the module to which it is moved.
SNOMED CT components may be promoted from an extension module into a less dependent module to enable broader use. For example, an extension concept may be promoted to the International Edition to enable SNOMED CT users to share the concept. Please note that a component may only be promoted to a module on which the extension module depends (as specified in the module dependency reference set).
When promoting components from an extension into the International Edition, the donating organization (i.e., the owner of the extension) should submit a promotion request to SNOMED International with the details of all components to be promoted. The SNOMED International authoring team process the request and consider whether the content is acceptable for inclusion in the International Edition.
Once promoted, a new version of the component is available in the International Edition with a new EffectiveTime , an international moduleId , and the same SNOMED CT identifier as was used in the originating extension. From that point forward, SNOMED International becomes responsible for maintaining the promoted content. Future releases of the extension content alone, which are dependent on the new version of the International Edition (that contains the promoted content), will no longer include the promoted content in their Snapshot and Delta release files.*1 The promoted content will, however, continue to appear in the Full release files of the extension Edition with an older EffectiveTime to reflect the ownership history of this content within the extension. Please note that the SNOMED CT identifiers of all promoted content will remain unchanged, and will therefore continue to include the namespace identifier of the originating organization.
Please note that it is essential that the promoted content is not inactivated in the extension from which it was promoted, as this would make it appear to users of the extension that the content is inactive. It is also important that the meaning of the content remains the same after it has been promoted, to ensure that the component identifiers permanently represent the same clinical meaning.
The diagram below illustrates how extension content is promoted to the SNOMED CT International Edition.
In some circumstances it may be necessary to demote SNOMED CT components. Demotion means moving a component from a given module to a module that is dependent on it. For example, moving a concept (and its associated descriptions and stated relationships) from the International Edition to a National Extension.
Content demotion is generally not recommended, because there are several risks associated with the management of demoted content. Once demoted, a different version of the component will be seen in different editions, and this redundancy needs to be managed carefully. Consideration should, therefore, be given when making the decision to demote a component.
If content demotion is deemed necessary, then it is very important to use a safe approach. As shown in the diagram below, the recommended approach for demoting SNOMED CT content is to inactivate the component in the source module and activate the component in the destination module at a more recent effective time.
Updates should also be made to the respective component inactivation reference sets to indicate that the component has been inactivated. For more information on inactivation and historical associated reference sets, see .
The following diagram shows the RF2 file changes that are required to demote an example concept from the international edition to an extension module. Please note that it is essential that the effectiveTime of the active component in the destination module is more recent than the effectiveTime of the inactive component in the source module. This is done to ensure that the demoted component is seen as active in any edition that uses the extension module to which it was demoted.
When a concept from the International Edition is inactivated but still in use nationally, action is needed to resolve this. Inactivated concepts should generally not be used in production systems and should be replaced with active concepts, typically guided by historical associations. However, in some cases, circumstances may require continued use of an inactivated concept. This document provides guidance on the principles and considerations involved in managing such scenarios.
The answer to this question is ‘sometimes’, but careful analysis is required before choosing to reactivate. Several factors need to be considered. In some cases, reactivation is strongly discouraged, while in others, it may be acceptable if handled correctly. Our overall advice is to approach reactivation cautiously, evaluating each case individually.
Before reactivating a concept, consider the following:
Reason for Inactivation : If reactivation is discouraged for a specific reason, a new concept that reflects the intended meaning may be the best option.
Type of Concept : The impact of reactivation varies by concept type. For example, reactivating an administrative concept inactivated due to being out of the scope of the International Edition, may be acceptable. However, reactivating a clinical concept inactivated due to ambiguity could compromise patient safety and should be avoided.
Usage : What is the frequency of use? How will the inactivation impact users and systems? There needs to be a good clinical use case or business reason for reactivation. It may be used as an interim step whilst a more long-term solution is put into place and then the concept in question is inactivated again. If the concept is used locally or within a single country, reactivation may be possible. However, if it supports cross-border interoperability, reactivation is strongly discouraged. In such cases, creating a new concept in your extension is preferred, ensuring that any involved consumers can unambiguously interpret the meaning.
Please note that multiple extensions may choose to reactivate an inactivated concept, resulting in multiple versions with potentially conflicting interpretations or uses. Therefore, it is essential that these reactivated concepts are not used for cross-border interoperability.
The table below summarizes the actions to take when considering reactivating an inactivated concept, depending on the reason for inactivation.
An inactivated extension concept may be reactivated in more than one extension module, however prior to doing so consideration needs to be given to
The potential for the meaning of the concept to be understood differently in different jurisdictions.
The potential for the use of the concept in more than one jurisdiction.
If the concept is reactivated in multiple extensions, one might assume that the meaning of the component is the same as the SCTID is the same. If this component is then exchanged between jurisdictions, there is the possibility of inaccurate interpretation of meaning.
The January 2021 International Release included the bulk inactivation of “on examination concepts. These concepts had come from the UK as part of CTV3 and were in high usage by UK GP’s. The UK NRC reactivated these concepts in bulk to prevent disruption to users. The concepts are now being reviewed and some are being inactivated within the UK extension.
In 2021, over 2000 concepts relating to breeds were inactivated from the international release and reactivated in the veterinary extension. Examples: 64158000 |Angora goat (organism)|, 62137007 |Labrador retriever (organism)|.
51631009 |Ligation of major artery of extremity (procedure)| was inactivated as ambiguous for September 2023 release. This concept should not be reactivated in an extension due to the ambiguity of the term ‘major’ - no clear definition of this exists.
When creating a new concept to replace an inactivated concept, it’s helpful to establish a historical association between the inactivated international concept and the active extension concept.
Historical associations are important because they form the backbone for maintaining continuity and traceability of clinical data when concepts are inactivated or replaced. These associations allow systems to link inactivated concepts to their appropriate replacements or related active concepts, ensuring that the integrity of historical data is preserved.
A key reason for establishing historical associations is to facilitate the querying of historical data using the Expression Constraint Language (ECL). ECL enables the retrieval of SNOMED CT concepts based on a range of criteria, including concepts with established historical associations. When a historical association is created between an inactivated concept and its replacement or related concept, history supplements enable users to include inactivated concepts in their queries. This ensures that historical clinical information remains accessible and interpretable, even as terminology evolves.
In most cases, historical associations will already exist between the inactivated concept and an active international concept. However, to ensure complete traceability, you should also create a historical association linking the inactivated concept to the new extension concept.
Please refer to the following pages to learn more about managing concept inactivation and historical associations:
Reference Set Practical Guide:
Expression Constraints Specification and Guide:
Reason for inactivation
Guidance
Considerations
Ambiguous
Do not reactivate
The historical association target concepts should be considered as replacements. In the event these are not suitable then a new unambiguous concept should be created.
Classification-derived component
Content type
Guidance
Considerations
Clinical concept
Discouraged
Consider the reason for inactivation
Administrative concept
May be reactivated
Discouraged
The historical association target concept(s) should be considered as replacements. In the event these are not suitable then a new unambiguous concept should be created.
Duplicate component
Do not reactivate
The active concept that has the same meaning as the inactivated concept should be used as the replacement.
Erroneous component
Do not reactivate
The historical association target concept(s) should be considered as replacements. In the event these are not suitable then a new unambiguous concept should be created.
Meaning of component unknown
Do not reactivate
A new unambiguous concept should be created.
Non-conformance to editorial policy
May be reactivated
The decision to reactivate depends on the type of content and usage.
Outdated component
May be reactivated
Clinically outdated (in most countries) - do not reactivateNot internationally semantically interoperable - may be considered for reactivation
Consider the reason for inactivation
Metadata concept
Discouraged
Referential integrity of the post-classification result should not be compromised
SNOMED CT components and reference set members are added, modified or inactivated according to the SNOMED CT editorial principles and policies.
General principles that apply to all SNOMED CT extension content include:
Organizations may add, inactivate or modify components and reference set members, which belong to modules owned by that organization.
It is the responsibility of the extension producer to ensure the quality and integrity of the extension is maintained, and that all content changes are made in a module that is owned by the extension producer themselves.
For more information about assigning modules in extensions, please refer to the section below on Module Assignment.
No changes are permitted to content of the International Release, except for the addition of new versions of this content in a module owned by the extension producer.
Any modifications resulting in changes to the classification of international content must be accompanied by a disclaimer notifying users of the differences between the extension edition and the International Edition. Please note that modifications of this kind pose a risk to the comparability and interoperability of data captured using different SNOMED CT editions.
Any substantive improvements or corrections to the content in the International Edition that is made in an extension should be forwarded to SNOMED International in a timely fashion to improve the quality of the International Edition for all users.
Extension producers should assign all new extension content to a module which they own. Therefore every concept, description, relationship and reference set member, which is managed within an extension, should belong to a module created and owned by the extension producer. As illustrated in the image below, this is accomplished by setting the moduleId attribute in each component and reference set file to a module concept that was created by the extension producer in the given extension. Any dependencies between components or reference set members in the extension module, and components or reference set members in other modules are specified in the .
For information on how to move content from one module to another, please refer to
Some reference sets, which belong to the International Edition (e.g. the and the ) were designed to be extended by adding new members in an extension module.
Other reference sets, which belong to the International Edition (e.g. ) may be adapted in an extension module, following the principles described in
