Draft Editorial Guidance

Introduction

SNOMED CT is a dynamic and evolving terminology in which the content must remain concurrent with current clinical practice and our evolving understanding of disease processes and treatments. As a result, content may change, become outdated, or as a result of improved understanding needs remodeling. However, individual patient records are created at a point in time and may use concepts that later become inactivated and replaced. For legal reasons, it is important that the concepts used at the time the record was made should persist over time and so in order to ensure that records made prior to a change in the status of that concept remain available to extraction routines both for population analysis and more importantly to ensure that individuals do not get lost to routine follow-up for ongoing care.

Managing and making transparent the history of a given concept over time is the responsibility of SNOMED International and this is achieved through the concept inactivation process. In order to make the process transparent, it is necessary to clearly document the reason for a given change in the status of a concept and provide vendors and users with the information necessary to understand those changes. Vendors can then use this information in such a way as to protect the meaning encapsulated in the individual's clinical record over time and ensure that decision support, routine analysis, and population studies can continue consistently and without

There are two key elements to the inactivation process, firstly allocating an appropriate reason for the concept inactivation and secondly providing a clear understanding of the level of semantic equivalence through the historical association link between the inactivated concept and it's replacement where it exists. To further improve the quality of our own audit trail additional information and links to reference sources can be added within text fields that accompany each inactivation.

The vendor can use the historical association 'type' to understand the level of semantic equivalence between the inactivated concept and its replacement and as a guide to what action should be taken by the end-user in updating their patient records and routine extraction routines in response to each inactivation.

Below is a summary of the inactivation reasons and the meaning of each of the historical associations and their implications for vendors/users. The link to the detailed guidance for each inactivation reason is provided

Inactivation Reasons

Inactivation Reason	Association	Summary Definition
Ambiguous Concept	POSSIBLY_EQUIVALENT_TO	The inactivated concept is inherently ambiguous, and each of the potential meanings represented by the concept is semantically identical to at least one other clinical concept.
Classification Concept	REPLACED_BY	The inactivated concept originates from the “closed world” classification paradigm and as such is inappropriate content for use within the clinical record.
Concept Moved Elsewhere	ALTERNATIVE	The jurisdictional control of a concept passes between extensions, or between the international core and an extension.
Duplicate Concept	SAME_AS	The inactivated concept semantically represents exactly the meaning of the remaining active concept. Note that the meaning of the concept is based on the FSN.
Erroneous Concept	REPLACED_BY	The inactivated concept has an FSN which contains an error that when corrected potentially changes the semantic meaning of the concept.
Meaning Unknown	No association required	The meaning of the inactivated concept cannot be determined.
Non-Conformance to Editorial Policy	REPLACED_BY ALTERNATIVE No suitable replacement identified	The inactivated concept does not comply with the current Editorial Policy and when updated to comply with the policy potentially changes the semantic meaning of the concept.
Outdated Concept	REPLACED_BY POSSIBLY_REPLACED_BY No suitable replacement identified	The inactivated concept is an outdated concept that is no longer considered to be clinically acceptable or semantically interoperable internationally.

Historical Associations

Association	Summary Definition
SAME_AS	For the Author: The SAME_AS association type exists to declare when any pair of different concept identifiers in fact represent exactly the same semantics. They are true semantic duplicates, for all time. Because of this statement of unambiguous and exact, bidirectional semantic equivalence, (A) SAME_AS (B) explicitly implies that everything ever subsequently said about B is, by definition, also true of A. (And, technically, also vice versa though, since A is inactive, nothing new should ever be said about it) Implications for the vendor/user: Given that the inactivated concept is semantically equivalent to the retained concept there should be no requirement for the user to either review the replacement or necessarily be aware of the inactivation.
POSSIBLY_EQIVALENT_TO	For the Author: The POSSIBLY_EQUIVALENT_TO association is to be used where an inactive concept was previously the conflation or disjunction of two or more distinct possible meanings, at least one of which is also now represented as a current SNOMED concept. The implication of a set of POSSIBLY_EQUIVALENT_TO associations is that all possible EPR instances previously coded to the inactivated code can be re-coded to one or other of the listed association concepts, without exception and also without either adding or losing any semantics not already expressed by the original coding. No other active concept either does - or could ever - exist that would more precisely capture what was expressed by a clinician originally selecting the inactivated code. Implications for the vendor/user: Where a POSSIBLY_EQUIVALENT_TO association is encountered this implies that a decision is to be made by the end-user as to which of the available POSSIBLY_EQUIVALENT_TO associations correctly represents the original meaning stated by the clinician. The vendor must provide adequate tooling to enable the end-user to view all of the POSSIBLY_EQUIVALENT_TO associations and select the most appropriate one to replace the inactivated concept.
EQUIVALENT_TO	The jurisdictional control of a concept passes between extensions, or between the international core and an extension.
RPLACED_BY	The inactivated concept semantically represents exactly the meaning of the remaining active concept. Note that the meaning of the concept is based on the FSN.
REPLACED_BY	The inactivated concept has an FSN which contains an error that when corrected potentially changes the semantic meaning of the concept.
POSSIBLY_REPLACED_BY	The meaning of the inactivated concept cannot be determined.
ALTERNATIVE	The inactivated concept does not comply with the current Editorial Policy and when updated to comply with the policy potentially changes the semantic meaning of the concept.
	The inactivated concept is an outdated concept that is no longer considered to be clinically acceptable or semantically interoperable internationally.

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Draft Editorial Guidance

Introduction

Inactivation Reasons

Historical Associations

Editorial Guidance