As clinical practice evolves and adapts to meet the changing needs of healthcare advances, it is important that SNOMED CT reflects these changes, so that clinicians can content is updated to address these changes. Reference sets may also need to be updated to reflect content changes and to enable clinicians to adequately represent new and emerging techniques /and practices. For any implementation of SNOMED CT it It is therefore important to establish processes for end users and other stakeholders to submit requests for changes. Related to reference sets the types of changes that may be required include:

• Inactivation Addition of new reference set membersAddition
• Removal of new reference set members
• Changes to existing reference set members

Types of

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Reference Set Changes

Addition of New Reference Set Members

Inactivation of reference set members

As for any components in SNOMED CT, reference set members are inactivated if they are no longer required as part of the reference set. The RF2 versioning mechanism is also embedded in the reference set design, which enable full history tracking of each reference set similarly to the SNOMED CT components.

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When new members are requested for inclusion in a reference set, it should be determined whether any existing components in SNOMED CT are sufficient, or whether it requires a new component to be added - either in the International Edition or as part of an Extension.

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Removal of Reference Set Members (Inactivation)

To remove a referenced component from a reference set, the relevant reference set member is inactivated. This is done by adding a new row to the reference set in which the value of the active column is set to false. The SNOMED CT versioning mechanism tracks the full history of additions, changes and inactivations because each row in the reference set contains a effective time column indicating when the change became effective. This is the same versioning mechanism with is used to track addition, inactivation and modification of SNOMED CT components.

Changes to Existing Reference Set Members

Changes to reference set members can vary, dependent on the refset type and the situation. Examples of changes include:

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