Introduction

Background

SNOMED CT terminology provides a common language that enables a consistent way of indexing, storing, retrieving, and aggregating clinical data across specialties and sites of care.

SNOMED International maintains the SNOMED CT technical design, the content architecture, the SNOMED CT content (includes the concepts table, the descriptions table, the relationships table, a history table, and ICD mappings), and related technical documentation.

Purpose

This document provides a summarized description of the content changes included in the January 2021 release of SNOMED Clinical Terms^® (SCT) International Release.

It also includes technical notes detailing the known content or technical issues where the root cause is understood, the fix has been discussed and agreed to, but has yet to be implemented.

The SNOMED International Release Notes are available alongside the January 2021 International Edition release.

Scope

This document is written for the purpose described above and is not intended to provide details of the technical specifications for SNOMED CT or encompass every change made during the release.

Audience

The audience includes National Release Centers, WHO-FIC release centers, vendors of electronic health records, terminology developers and managers who wish to have an understanding of changes that have been incorporated into the January 2021 International Edition release.

Content Development Activity

Summary

Continuous quality improvement and enhancement of existing content is an ongoing process undertaken by SNOMED International in preparation for every release. The January 2021 International Release has seen a continuation of the work driven by contributions from: Kaiser Permanente i.e. Convergent Medical Terminology (CMT), Global Medical Device Nomenclature Agency (GMDNA), Orphanet and other domain specific collaborations as well as requests received via the Content Request System (CRS). 

Additionally quality improvement activities are advanced via project driven initiatives summarized below.  Additional, work items impacting every release are updates to the SNOMED CT derived maps such as ICD-10 and ICD-O; details are included in these release notes.  

Information about editorial decisions may be found in the SNOMED CT Editorial Guide; mapping guidance for ICD-10 can be found at this link https://confluence.ihtsdotools.org/display/DOCICD10

COVID-19

New content has been added to SNOMED CT as part of the ongoing global effort to tackle the Coronavirus pandemic.

Content relating to COVID-19 can be viewed here SNOMED CT COVID-19 Related Content

Any concepts in scope for the SNOMED CT to ICD-10 mapping have been mapped and adhere to the World Health Organization current guidelines.

Content Quality Improvement

Body structure 

New body structure concepts: 383

Planned revision of Cell hierarchy in the January 2021 release

The content under 4421005 |Cell structure (cell structure)| will be updated according to the SEP model and description patterns. Descendants of 362837007 |Entire cell (cell)| will be updated to include the word ‘entire’ in all descriptions. The semantic tag ‘(cell)’ will be changed to ‘(cell structure)’. Descriptions for the rest of the concepts will be updated to include the word ‘structure’.
This improvement will reduce the potential misuse of cell concepts.

Please contact info@snomed.org with any inquiries or to submit feedback.

Reference set updates

Updated and validated release file for the lateralizable body structure reference set.
Updated and validated release files for the SEP refsets.

Clinical finding

New concepts added for clinical finding hierarchy: 1702

Quality Initiative

The Quality Initiative (QI) project is the implementation of the Quality Strategy. After a successful pilot project for the July 2018 release the next stage has been implemented for subsequent releases including January 2021. 

Quality improvement tasks were deployed to improve internal structural consistency and ensure compliance with editorial policy related to the stated modeling of content. Additionally, correction or addition of defining relationships was carried out to accurately reflect current clinical knowledge and ensure the semantic reliability of descriptions associated with a concept.

Total count of changes for the QI project: 

• Stated: A total of 9463 concepts had changes made to the Stated relationships in the model. 
• Inferred: A total of 15750 concepts affected by inferred changes.

269061001|Fracture of vertebra without spinal cord lesion (disorder)

Based on input from the Editorial Advisory Group and a member stakeholder:

269061001 |Fracture of vertebra without spinal cord lesion (disorder)| and descendants have been inactivated with a status of 'Ambiguous' and the historical association POSSIBLY EQUIVALENT TO = 50448004|Fracture of vertebral column (disorder)|. These concepts originated from ICD-9 to represent the notion of "Fracture of X without mention of Y". 

This type of term is not represented in ICD-10 or ICD-11. As "without mention" is not semantically equivalent to "without" and could mean that the information was not available in the record abstraction, these concepts are considered to be ambiguous in their meaning.

419199007|Allergy to substance (finding)

As part of the QI project review of the 419199007 |Allergy to substance (finding)| sub-hierarchy and per the Allergies CRG recommendation, the concepts in this sub-hierarchy that represent allergy to "role groupers" and "Structure + role groupers" will be inactivated starting from the July 2020 release.

A few examples of these concepts are provided below:

• • 294450008 Allergy to anthelmintic agent (finding)
  • 294461000 Allergy to antibacterial drug (finding)
  • 294869008 Allergy to anticoagulant (finding)
  • 293857007 Allergy to anticonvulsant (finding)

12456005 |Iatrogenic disorder (disorder)

Subtypes of 12456005 |Iatrogenic disorder (disorder)| that do not have the word iatrogenic in the FSN have been remodeled so that they are no longer a subtype of this concept.

New subtypes have been added to 12456005 |Iatrogenic disorder (disorder)| where the disorder specifies iatrogenic in the FSN.

25674000|Lichen sclerosus et atrophicus (disorder)

25674000 Lichen sclerosus et atrophicus (disorder) has been inactivated with reason outdated and replaced with new concept 895454001 Lichen sclerosus (disorder).

A new morphology concept 895217008 Lichen sclerosus (morphologic abnormality) has been created and used to remodel the new concept and its 20 descendants. This improvement has resulted in 895454001 Lichen sclerosus (disorder) having no stated subtypes (with all Sufficiently Defined where possible).

40275004 |Contact dermatitis (disorder)

Updated the modeling for 40275004 |Contact dermatitis (disorder)| and subtypes to adhere with a newly constructed template.

52515009|Hernia of abdominal cavity (disorder)

The finding site value for hernia disorder concepts (excluding obstructed hernias which are being managed separately) were reviewed and changes made where required to improve classification results.

106112009|Fetal finding (finding)

The value for the 363698007 |Finding site| attribute for fetal concepts has been updated to << 123037004 |Body structure| MINUS << 55460000 |Fetal structure| unless the site is a unique body structure present during the fetal period.

The fetal semantics are captured using the 246454002 |Occurrence|=303112003 |Fetal period| relationship. These modeling changes has been applied to the fetal content within the Clinical finding hierarchy. Fetal procedure concepts will be reviewed as part of the Procedure QI work.

206002004|Fetal or neonatal effect of maternal medical problem (disorder)

206002004|Fetal or neonatal effect of maternal medical problem (disorder)| and descendants has been inactivated. Replacement concepts that do not include 'or' in the descriptions have been added as subtypes of 70591005|Fetal disorder (disorder)| and 22925008|Neonatal disorder (disorder)|.

Content Tracker Project Updates

Work on hold on the following Content Project:

• IHTSDO- 393 Diabetes Complications - The Diabetes Project Group comprises practicing clinicians. As a result of the COVID-19 pandemic the majority of the participating clinicians have been drafted into supporting the response to this health care crisis. Consequently this project has been put on temporary hold until the pandemic is under control and healthcare staff are able to return to their normal duties. 

Work completed for the following Content Project: 

• IHTSDO-1157 Distinction between Pain and Tenderness. Improvement in the modeling of the Tenderness (finding) sub-hierarchy. 

Other Content Improvements in the Clinical Finding Hierarchy

'On Examination' and 'Complaining of' concepts

'On examination' and 'Complaining of' concepts have been inactivated in the International Edition and moved back to the UK extension.

Disorder X without Disorder Y

The vast majority of existing X without Y concepts originated from ICD-9 with the specific meaning of "X disorder without mention of Y disorder".  As the phraseology indicates a lack of data about disorder Y as opposed to a specific exclusion, this type of concept has not been included in ICD-10, nor proposed for ICD-11, except in the case of "Traumatic brain injury without open intracranial wound".  

Addition of new X without Y concepts may only be made under the following conditions:

1. The request for new content must be accompanied by a rationale as to the difference between "X disorder without Y disorder" and "X disorder."
2. Approval for addition is given by the Head of Terminology.

For the most part, existing X without Y concepts will be inactivated as AMBIGUOUS with a historical MAY BE relationship to "X disorder".  Exceptions to inactivation will be made on a case-by-case basis.

253530007 |Right ventricular outflow tract obstruction (disorder)| and253546004|Left ventricular outflow tract obstruction (disorder)

Occurrence 'congenital' has been removed from these two concepts with remodel of subtypes.

165816005|Human immunodeficiency virus positive (finding)

Human immunodeficiency virus Centers for Disease Control and Prevention and Human immunodeficiency virus World Health Organization class content has been updated to align with the current categories.

268294001 |Chromosome replaced with ring or dicentric (disorder)

268294001 |Chromosome replaced with ring or dicentric (disorder)| has been inactivated and replaced by 1010276004 |Ring chromosome (disorder). All subtypes have been remodeled and marked sufficiently defined where appropriate. 23345003 |Ring chromosome (morphologic abnormality)| has been remodeled to align with expert input to have monosomy, trisomy and ring chromosome concepts as siblings in the morphology hierarchy.

Convergent Medical Terminologies (CMT)

New CMT concepts: 714

• Injury - 162 concepts added.
• Ophthalmology - 552 concepts added.

Procedure

New concepts for procedure hierarchy: 299

Implantation and Insertion procedures

Work continues on content tracker IHTSDO-175. There are ongoing structural changes for the Procedure concepts related to the content tracker. Work on this project will continue for future releases after July 2020.

Content Inactivation - Anesthesia

These concepts have been inactivated from the International release and moved to the US extension:

• 67902001 |Anesthesia for a normal healthy patient (procedure)|
• 23102000 |Anesthesia for a patient with mild systemic disease (procedure)|
• 22211001 |Anesthesia for a patient with severe systemic disease (procedure)|
• 112989003 |Anesthesia for a moribund patient requiring operation (procedure)|
• 71191009 |Anesthesia for a patient with severe systemic disease, life threatening (procedure)| 
  

Content Inactivation - Monitoring

These concepts have been inactivated from the International release and moved to the UK extension:

• 391023009|Osteoporosis - no treatment (regime/therapy)|
• 391030003|Osteoporosis - no treatment response (regime/therapy)|
• 391028000|Osteoporosis - treatment response (regime/therapy)|
• 391003008|Osteoporosis monitoring administration (regime/therapy)|
• 391004002|Attends osteoporosis monitoring (regime/therapy)|
• 391006000|Osteoporosis monitoring default (regime/therapy)|
• 391012005|Osteoporosis monitoring deleted (regime/therapy)|
• 391007009|Osteoporosis monitoring first letter (regime/therapy)|
• 391008004|Osteoporosis monitoring second letter (regime/therapy)|
• 391011003|Osteoporosis monitoring telephone invitation (regime/therapy)|
• 391009007|Osteoporosis monitoring third letter (regime/therapy)|
• 391010002|Osteoporosis monitoring verbal invitation (regime/therapy)|

Evaluation Procedure

• New evaluation procedure concepts - 10 (respiratory procedures, specimen processing and laboratory panels).
• Concept inaction - 13 (inactivated due to duplication or ambiguity).

Collaboration/Harmonization Projects

Orphanet

Working in collaboration with Orphanet (http://www.orpha.net/consor/cgi-bin/index.php), creation of new concepts for the original set of prioritized rare diseases has been completed. The alpha release is now available for feedback, for more information please see April 2020 SNOMED CT Orphanet Simple Map package ALPHA release available

All of the concepts added for the Orphanet project have been mapped to ICD-10. 

ICD-11 Update

A total of 593 new concepts were added for the July 2020 release.

Global Medical Device Nomenclature Agency (GMDNA)

33 new device concepts were added to the physical object hierarchy for GMDN for the January 2021 release.

 For the GMDN mapping equivalence tables: 

• 33 new concepts have been added to in scope and mapped.
• 199 concepts have been modified and removed from the mapping tool as out of scope.
• 84  concepts have been deemed obsolete and removed from the mapping tool and flagged as out of scope.
• 16 concepts have been flagged as out of scope for SNOMED CT and removed from this map.

ICD-O-3.2 Update

A full Impact analysis of both updating the existing SNOMED CT content and updating the current ICD-O-3.1 map has been carried out. In particular this relates to changes to the 400177003 |Neoplasm and/or hamartoma (morphologic abnormality)| sub-hierarchy in SNOMED CT. The impact analysis utilized the final IACR ICD-O-3.2 (WHO IARC) morphology code listing and the new pdf changes documents on their website (http://www.iacr.com.fr/index.php?option=com_content&view=category&layout=blog&id=100&Itemid=577).

For the July 2020 release only minor changes have been made, and 14 new morphologies have been added to the 108369006 |Neoplasm (morphologic abnormality)| sub-hierarchy.

Note - The published maps to ICD-O-3.1 are being updated only for maintenance purposes for the July 2020 release. The maps to ICD-O-3.2 are out of scope for the July 2020 release and are planned for a future release.

Event

New concepts added: 4

Qualifier Value

New concepts added: 65

Occupation

Concepts representing "other" occupations e.g. 79445009 |Other clerk (occupation)| have been inactivated as ambiguous as these represent classification constructs.

Situation with explicit context 

New concepts added: 129

Physical object

New concepts added: 89

• Approximately 200 device concepts in the physical object hierarchy were modeled with the new device attributes in the areas of breast implants, shunts, stent, and cardiac valve prosthesis. Some of these concepts also had FSN and description changes.
• 25 concepts in the physical object hierarchy were inactivated.
• Approximately 630 attribute-value relationships were added to the physical object hierarchy including device characteristic such as sterility, absorbability, and custom-made.
• Editorial guidelines developed and documented and noted content updated accordingly. The guidelines are found on the project space: Reference Documentation - Devices (Please note, you may have to register for Confluence user account in order to access this project and the relevant link).
  

Specimen

New concepts added: 8

Concepts inactivated: 2

Observable Entity 

New concepts added: 117

• 30 new concepts were added in the areas of novel coronavirus detection, insulin rates and doses, test due dates, minimum alveloar concentration.
• Estimate intake of X = 30 concepts new concepts
• Measured intake of X = 30 concept new concepts
• Proportion of X  = 3 new concepts
• Target = 4 new concepts

Organism

New organism concepts added: 135.

Updated descriptions for 60 concepts.

Pharmaceutical / biologic product

Veterinary Extension

23 concepts were moved to the Veterinary Extension.

Metadata concept

In order to support the upcoming RF2 version of the GPS (Global Patient Set) refset, the GPS requires its own moduleID.

A new concept has been added to support this use case 890195008|International Health Terminology Standards Development Organisation Global Patient Set module (core metadata concept)|

Content development activity summary

The map is a directed set of relationships from SNOMED CT source concepts to ICD-10 target classification codes.  The SNOMED CT source domains for the MAP are limited to subtypes of 404684003 |clinical finding|, 272379006 |event| and 243796009 |situation with explicit context|.  The target classification codes are ICD-10 2016 release. 

 Mapped content for January 2021

The map provided for the January 2021  release has been updated, and now represents a complete map from SNOMED CT International release to ICD-10 2016 version.

• 1873 newly authored concepts have been added and mapped
• 3 new codes for special purposes  have been added to the terminology browser in accordance with WHO guidelines:

• · U08 Personal history of COVID-19

  · U09 Post COVID-19 condition

  · U10 Multisystem inflammatory syndrome associated with COVID-19

  
  

  We would welcome feedback on any issues that users of the map may detect when using the map. Issues should be submitted via mapping@snomed.org

Technical Guide Exemplars

The Technical Guide Exemplars document has now been moved from the International Edition release package to a Confluence page.  This page can be found as part of the ICD-10 Mapping Technical Guide (see Appendix B), which is hosted here:  http://snomed.org/icd10map

ICD-O Map

For the July 2020 release only minor changes have been made, and 14 new morphologies have been added to the 108369006 |Neoplasm (morphologic abnormality)| sub-hierarchy.
The published maps to ICD-O-3.1 are being updated only for maintenance purposes for the July 2020 release. The maps to ICD-O-3.2 are out of scope for the July2020 release and are planned for a future release.

SNOMED CT to OWL conversion and classification

The repository containing the toolkit enabling simple SNOMED CT to OWL conversion and classification can be found here, including documentation on its use: https://github.com/IHTSDO/snomed-owl-toolkit

Please contact SNOMED International at support@snomed.org if you would like to provide any feedback on ways to extend and improve the new toolkit.

Technical notes

Known Issues

Known Issues are content or technical issues where the root cause is understood, and the resolution has been discussed and agreed but has yet to be implemented.  This can be due to a number of reasons, from lack of capacity within the current editing cycle, to the risk of impact to the stability of SNOMED CT if the fix were to be deployed at that stage in the Product lifecycle.  

For the SNOMED CT July 2020 International edition, the following Known Issues were identified, and agreed to be resolved in future editing cycles:

Resolved Issues

Resolved issues are Known Issues which were not fixed as part of the previous release lifecycle, but which have now been resolved in the latest release.  They can also be issues found during the Alpha and Beta testing of the current release, which were resolved before the final deployment of the associated Member release.  Finally they can be issues which were reported or found during the testing phase, but which have been closed without any action taken.  

The Resolved Issues for the Snomed CT July 2020 International edition can be found here:

Technical updates

RF2 package format

For future reference, the RF2 package convention dictates that it contains all relevant files, regardless of whether or not there is content to be included in each particular release.  Therefore, the package contains a mixture of files which contain both header rows and content data, and also files that are intentionally left blank (including only a header record).  The reason that these files are not removed from the package is to draw a clear distinction between files that:

• have been deprecated (and therefore removed from the package completely), due to the content no longer being relevant to RF2 in this or future releases, and 
• happen to contain no data in this particular release (and are therefore included in the package but left blank, with only a header record), but are still relevant to RF2, and could therefore potentially contain data in future releases.

This allows users to easily distinguish between files that have purposefully been removed or not, as otherwise if files in option 2 above were left out of the package it could be interpreted as an error, rather than an intentional lack of content in that release.

New Configuration file in the RF2 package, containing Release Metadata 

A new file will be included in the July 2020 International Edition (and all subsequent releases), containing metadata about the Release package itself.  This has been created in conjunction with feedback from the community, and as such will initially contain the following fields:

• effectiveTime
  
• deltaFromDate
  
• deltaToDate
  
• languageRefset(s)
  
• humanReadableLanguageRefset(s)
  
• licenceStatement
  

The file will be in .JSON format, to ensure that it is both machine-readable and human-readable.  It will be named "release_package_information.json".

The metadata will be extended and refined going forward, in order to ensure that it contains the most useful information possible. If anyone has any ideas about any other useful information to include, please send them to info@snomed.org, along with a business case explaining how the information would benefit stakeholders.  Please be aware that this use case will then be assessed by SNOMED International, and the new metadata will only be included in the configuration file if the business case is strong enough.  

Additional Rollup Delta Release package

For those users who did NOT use the March 2020 Interim International Edition release in their systems, the advise on bringing systems up to date is as follows:

1. The best option is to first apply the March 2020 Interim release Delta files (relative to the January 2020 release), and after that apply the official July 2020 Delta files (relative to the March 2020 Interim release).
2. If this is not feasible, then please use the July 2020 International Edition additional Rollup Delta package - please see the Release Notes for full details:
   1. https://confluence.ihtsdotools.org/display/RMT/SNOMED+CT+July+2020+International+Edition+additional+Rollup+Delta+package+-+SNOMED+International+Release+notes

Early visibility of impending change in the July 2020 International edition

Please see the following page for details of all upcoming changes planned for July 2020 and beyond:  https://confluence.ihtsdotools.org/display/RMT/July+2020+Early+Visibility+Release+Notice+-+Planned+changes+to+upcoming+SNOMED+International+Release+packages.

Release Notes naming convention

The Release notes naming convention has been refined to bring it in line with other documentation standards - from this release onwards the files will have the following naming format:

• • doc_SnomedCTReleaseNotes_Current-en-US_INT_[date].pdf

   Instead of the previous underscore after "Current":

• • doc_SnomedCTReleaseNotes_Current_en-US_INT_[date].pdf

Document links

All links provide information that is correct and current at the time of this Release.  Updated versions may be available at a later date, but if so these will need to be requested from the relevant SNOMED International teams.