Page History

Overview

SNOMED CT is an international standard terminology. Therefore, maintenance of the terminology must be seen to adhere to standards that are open and transparent with a clear audit trail for each change made. This is particularly important where a SNOMED CT concept is inactivated and replaced with one or more concepts linked by historical associations or in exceptional cases, where no replacement is deemed necessary.

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Overview

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 As a result, content may change, become outdated, or as a result of improved understanding needs remodeling.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.

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