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Changes to digital terminologies

View details of the planned changes to dm+d and SNOMED CT UK Drug Extension digital terminologies and the delivery timeline.

Digital Medicines is standardising a seamless exchange of information about patient medications, allergies, intolerances and prescriptions across all NHS clinical IT systems. 

Currently there are gaps in end-to-end exchange of medicines data meaning manual transcription is involved which is open to clinical error.

To reduce this risk, several changes are being made to dm+d and SNOMED CT UK Drug Extension during 2023 and 2024 to make these two terminologies more closely aligned in terms of content and availability.

This will improve safety and efficiency, reduce transcription and clinical errors and allow staff to focus even more on care and provide patients with a better experience.


Issues to resolve

There are differences between the content in dm+d and SNOMED CT UK Drug Extension.

There are also differences between the release cycles of the data. This means the same medication may have different information published about it depending on when the most recent release is available to the user. This creates confusion and challenges for interoperability. Sometimes there is a time lag of up to 6 weeks before the same data is published in both terminologies.


Changes to dm+d content

Addition of dm+d historical codes​ as an (XML) release file

To support other enhancements, end users will need access to dm+d historic codes to ensure medications that have had more than one code change can still be correctly found. 

To avoid affecting existing products and process flows, the dm+d historic codes will be added as an added XML release file with the dm+d weekly release and into the Terminology Server.

What to consider

  • If your system supplier manages your dm+d data, ask them if and how they plan to use this data
  • If the trust manages dm+d data, will you start to use this data? 
  • Which dm+d concepts do you use that contain fields for ‘current’ and ‘previous IDs’

The dm+d historic code file will be a bonus/supplementary file within the weekly TRUD release.

Historic code data files will be found in the ZIP file under a folder named: HISTORIC_CODES

XML filename format: f_history1_0DDMMYY.xml

XSD filename: history_V1_0.xsd

Update current dm+d VTM content to link to 'contains only' Medicinal Product concepts in SNOMED International Edition

dm+d virtual therapeutic moietys (VTMs) and virtual medicinal products (VMPs), where an equivalent exists, use SNOMED CT International Edition (IE) concept identifiers as their unique ID. Recent changes to the IE model and editorial policy mean that the IE definition of VTM and the dm+d definition no longer align. 

In dm+d, the VTM groups together VMPs that have only that VTM - for example, paracetamol and codeine VMPs are not children of paracetamol VTM.

The IE definition of these existing concepts (that dm+d is linked to) has changed to ‘contains some’. That is, the VMPs below a VTM have this VTM and possibly others too, whilst concurrently introducing new ‘contains only’ concepts. Therefore, some dm+d VTMs are now linked to incorrect IE concepts.

This will have implications on implementations using VTM/VMP inheritance and links to support - for example, allergy.

All VTMs using IE codes will be changed to the correct ‘contains only’ VTM where applicable. Where a new IE ‘contains only’ VTM does not exist, a UK extension ID will be assigned.

What to consider

  • Do you use/map to VTM concepts?
  • If your system supplier manages your dm+d data, ask them how they plan to make these changes in their systems and what impact there may be to end users
  • How will dm+d updates be managed where you have systems that integrate with each other?
  • If the trust manages dm+d data, what will be the process for taking and handling the code changes in dm+d updates? Do you use ‘current’ and ‘previous’ VTM IDs?

The availability of dm+d ‘historic codes’ will support you with these changes.

Shift to use of UK extension IDs for all VMP concepts in both dm+d and SNOMED CT UK Drug Extension

dm+d VTMs and VMPs (where an equivalent exists) use SNOMED CT International Edition (IE) concept identifiers as their unique ID. Recent changes to the SNOMED CT IE model and editorial policy mean that the IE definition of VMP and the dm+d definition no longer align. This change in the IE led to a requirement to update the concept ID for several hundred high volume (usage) VMPs in dm+d. The impact was destabilising for EPS and has led to mistrust in the stability of the dm+d product long term.

To shield EPS from further ‘unplanned for’ changes, because of IE churn, it is proposed to move all VMPs to extension ID and no longer use IE concept identifiers. This would mean a one off, managed, implementation of change but would mean protection (of dm+d) from any further instability created by international change.

The link to the SNOMED CT IE would be at VTM level as content at this level is stable, hence minimal risk of churn despite keeping international identifiers.

Addition of Ingredients for VTMs in dm+d (XML) release files and SNOMED CT UK Drug Extension

In dm+d, ingredients are authored for VMPs but not currently for VTMs. VTM-Ingredient link information cannot be derived from any content currently in dm+d. A VTM can, at times, have an ingredient that is a level of abstraction above the VMP ingredient - for example, base vs salt.

Ingredients will be added for VTMs at time of authoring as it will aid in the modelling/classification of the SNOMED CT UK Drug Extension content.

Addition of 'Trade Family' and 'Trade Family Group' to dm+d (XML) release files

The SNOMED CT UK Drug Extension has a ‘6th box’ – the Trade Family (and a link to an associated Trade Family Group that groups together trade names that have, for example, different active ingredients), a brand equivalent to a VTM. This extra data is not available in the native dm+d XML release.

Trade Family and Trade Family Group will be added to the dm+d authoring process and extra XML files produced for this information to be distributed with the native dm+d XML release. This will streamline the process for implementers with a need for Trade Family and Trade Family Groups but who only use dm+d (and not the SNOMED CT UK Drug Extension).


Changes to SNOMED CT UK Drug Extension content

Addition of Ingredients for VTMs in dm+d (XML) release files and SNOMED CT UK Drug Extension

In dm+d, ingredients are authored for VMPs but not currently for VTMs. VTM-Ingredient link information cannot be derived from any content currently in dm+d. A VTM can, at times, have an ingredient that is a level of abstraction above the VMP ingredient - for example, base vs salt.

Ingredients will be added for VTMs at time of authoring as it will aid in the modelling/classification of the SNOMED CT UK Drug Extension content.

Stated parent(s) for ingredients and 'modification of' defined for dm+d content - extra modelling to be added to the SNOMED CT UK Drug Extension

dm+d uses SNOMED CT substances as the ‘ingredients’ assigned in the dm+d model. These substances in dm+d are currently a flat file with no associations/links between them.

NHS England will define a correct hierarchy for substances within the SNOMED CT UK Drug Extension to enable correct classification of drug extension content (allowing better QA and automated build) and to support implementors in their use of ingredient content.

This will become increasingly important on the implementation of Identification of Medicinal Products (IDMP) standards and alignment to it for interaction with MHRA data and use in the International Patient Summary.

Stated parent(s) for form and unit of measure concepts defined for dm+d content - extra modelling to be added to the SNOMED CT UK Drug Extension

dm+d uses SNOMED CT forms and units of measure in the dm+d model. These are currently flat files in dm+d with no associations/links inherent in each file.

NHS England will define a correct hierarchy for form and unit of measure within the SNOMED CT UK Drug Extension to enable correct classification of drug extension content (allowing better QA and automated build) and to support implementors in their use of form and unit of measure content.

This will become increasingly important on the implementation of Identification of Medicinal Products (IDMP) standards and alignment to it for interaction with MHRA data and use in the International Patient Summary.

Update SNOMED UK Drug Extension model​ to reflect the SNOMED International model for national drug extensions

The above enhancements will amend the SNOMED CT UK Drug Extension model, implementing new modelling available within the SNOMED CT environment. Developments in the International Edition mean the bespoke UK Drug Extension build can now be redesigned to ensure alignment between the UK Drug Extension and SNOMED CT International. 

To support quicker processing of dm+d data within NHS England and enable the 4 weekly SNOMED CT UK Drug Extension release to be published 2 days after the weekly dm+d release, a bi-directional data feed will be built, allowing NHS England to work on closer to real time data and thus reduce post dm+d release processing time. This will move closer to supplying a ‘synchronous’ dm+d and SNOMED CT UK Drug Extension content every 4 weeks.


Proposed timescales

The schedule below provides the intended delivery dates, but they are subject to change. Please visit this page on a regular basis to ensure you are aware of the latest delivery dates.

Changes Current delivery forecast Supporting resources
Addition of dm+d historical codes​ as an (XML) release file Live from 16 January 2023  
Updating current dm+d VTM content to link to 'contains only' medicinal product concepts in SNOMED International edition

Live from 13 February 2023

Remaining updates -  from April 2023 

File VTM content to link to contains only

Shift to use of UK extension IDs for all VMP concepts in both dm+d and SNOMED CT UK Drug Extension

Live 27 February 2023 - sample batch

Live 20 March 2023 - sample batch 02

Live from 8 May 2023 - see batch information for details

Batch information

Identifying VMP ID Changes

Addition of 'Ingredients for VTMs' in dm+d (XML) release files and SNOMED CT UK Drug Extension Quarter 2 2024  
Addition of 'Trade Family' and 'Trade Family Group' to dm+d (XML) release files To be confirmed  
Stated parent(s) for ingredients and 'modification of' defined for dm+d content  From 25 September 2023  
Stated parent(s) for form and unit of measure concepts defined for dm+d content - extra modelling to be added to the SNOMED CT UK Drug Extension

Phase 1 forms from 20 November 2023

Phase 2 forms - Quarter 1 2024

Further information on drug forms

Identifying VMP drug form changes

Updating SNOMED UK Drug Extension model​ to reflect the SNOMED International model for national drug extensions To be confirmed  

Aligning the release cycles

Once the content changes to dm+d and SNOMED CT UK Drug Extension have been completed, the release cycles of dm+d and SNOMED CT UK Drug Extension will become more closely aligned so that every 4 weeks, both data sets are released within a couple of days of each other.

Details will be announced in due course.


Further help

If you have any specific queries relating to the dm+d and SNOMED CT UK Drug Extension changes, please contact [email protected].

Last edited: 9 January 2024 5:08 pm