1 Introduction

1.1 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.

1.2 Purpose

This document provides a summarized description of the content changes included in the January 2017 release of SNOMED Clinical Terms^® (SCT) International Release.

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

This document is available alongside the January 2017 International Edition release.

1.3 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.

1.4 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 2017 International Edition release.

2 Content Development Activity

2.1 Summary

Continuous quality improvement and enhancement of existing content is ongoing based on requests received via the Content Request System (CRS). The January 2017 International Release has seen a continuation of the work driven by contributions from the Kaiser Permanente Convergent Medical Terminology (CMT), Global Medical Device Nomenclature Agency (GMDNA) and Orphanet to add new content to SNOMED CT.  Additionally, member-identified priority projects, have driven enhancements in the anatomy hierarchy, while other project-driven changes have resulted in new content additions and enhancements to existing content detailed below.

2.2 Content Quality Improvement

• In total: 5123 new concepts were authored with an additional 13899 changes made to existing concepts. 

  
  

2.2.1 Anatomy 

2.2.1.1 Laterality

To support systems that cannot implement post-coordination at the moment, the Editorial Advisory Group (EAG) approved the acceptance of requests for pre-coordination of concepts with laterality. 

• • New lateralized concepts have been added as follows:

1. 1. 1. 250+ in anatomy and
      2. 400 in disorder and procedure hierarchies

2.2.1.2 Structure/Entire/Part

• • The naming conventions for supporting the Structure/Entire/Part (SEP) model have been enhanced to resolve potential ambiguity between structure and entire concepts. All descriptions for Entire concepts must contain the word 'entire'.

1. 1. 1.  9,000 + descriptions without 'entire' have been inactivated and
      2. 3,600 + new descriptions added to facilitate searching

2.2.2 Clinical finding

• 23 new nutrition and dietetics concepts to support clinical documentation, care planning and research for nutrition. 
• 45 new laboratory finding concepts to support microbiology, chemistry and pathology

2.2.3 Convergent Medical Terminologies (CMT)

• 619 concepts were added for the January 2017 release, updating domains in Cardiology, Ophthalmology and Radiology.

2.2.4 Diagnostic Imaging Procedures

• 10 new concepts, Dual energy computed tomography and body site specific subtype concepts added

2.2.5 Functioning

• Disambiguation of the "Interpretation value (qualifier value)" hierarchy, with correction of approximately 600 findings using this as a target for an attribute

2.2.6 Disorders

2.2.6.1 Orphanet

• • As a result of collaboration with Orphanet (http://www.orpha.net/consor/cgi-bin/index.php) 700 new concepts have been created to represent rare diseases in the disorder hierarchy.

2.2.6.2 ICD-11 Harmonization plan

• • 1200 ICD-11 concepts added from the Mortality and Morbidity Linearization

2.2.7  LOINC

• 215 new concepts among the substance, Techniques, body structure hierarchies added to support antibody, antigen, DNA and RNA components needed to map to LOINC Parts. 

2.2.8 Observables

• Fully modelled more than 150 physiological measurement concepts (body temperature, respiratory rates, heart rates, blood pressure) based on the IHTSDO-979 Vital Signs Observables Inception/Elaboration document. 
• Created 10 required, metadata, attribute and range concepts in different hierarchies

2.2.9 Organisms

• 250 concepts to support microbiology reporting.

2.2.10 Physical objects

•  Concepts representing test kits were relocated from the Substance hierarchy to the Physical object hierarchy. Because the meaning of the concept was not changed, the concept IDs were retained. Duplicates were resolved; new FSNs were created. 
   

• Over 300 concepts with redundant IS A relationships were revised to remove redundancy
• Combined/compound allergy concepts inactivated as ambiguous
• Drug indicated (situation)| sub-hierarchy reviewed and modeling updated.
• Inactivated disjunctive substance concepts
• Created around 10 required metadata, attribute and range concepts in different hierarchies.

2.4 SNOMED CT derived products

2.4.1 ICD-10 map

The SNOMED CT to the International Statistical Classification of Diseases and Related Health Problems, Tenth Revision (© World Health organisation 1994) 2016 Version map (SNOMED CT to ICD-10 Map) is included in the SNOMED CT International release as a Baseline. The SNOMED CT to ICD-10 Map was created to support the epidemiological, statistical and administrative reporting needs of IHTSDO member countries and WHO Collaborating Centres.

The SNOMED CT to ICD-10 Map is released in Release Format 2 (RF2) only. It is located in the file der2_iisssccRefset_ExtendedMapFull_INT_20170131.txt, which is in the Map folder under Refset, in each of the three RF2 Release Type folders.

The SNOMED CT to ICD-10 Map is released as Refset 447562003 |ICD-10 complex map reference set (foundation metadata concept)|.

2.4.1.1 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.

All pre-coordinated concepts issued by the IHTSDO within the current international release of SNOMED CT with active status within the following SNOMED CT domains may be mapped:

2.4.1.2 Mapped content for January 2017

The map provided for the January 2017 release has been updated, and now represents a complete map from SNOMED CT International release to ICD-10 2016 version.

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

3 Technical notes

3.1 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 January 2017 International edition, the following Known Issues were identified, and agreed to be resolved in the next editing cycle (to be published in July 2017):

3.2 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 - in this case the January 2017 International Edition.  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 January 2017 International edition can be found here:

3.3 Technical updates

3.3.1  RF1 package

In line with the RF1 deprecation plan approved by the General Assembly in October 2015, SNOMED International has now removed the RF1 files from the International Edition release package.

There is a new open sourced program available from SNOMED International (under an Apache v2 open source license) that allows for an algorithmic derivation of RF1 files from the authoritative RF2 distribution.  This is available from Github here: https://github.com/IHTSDO/rf2-to-rf1-conversion

3.3.2  RF2 package naming convention

The naming convention of the RF2 package zip file has been improved, in order to reflect the version of the release package, within the existing Product name/Release Date version standard, as follows:

SnomedCT_[Product][Format(optional)]_[Release Status]_[Release date/time]

This format includes all of the additional information required to quickly and uniquely identify the correct package to use at any one time, without adversely impacting any of the related policies (such as the Snomed CT URI standard, etc).

3.3.3  Release Notes location

The Release Notes file has been removed from the zip file containing the main release package, and is now available as a separate file to be downloaded from the same MLDS version as the International Release package.  This is available from the “January 2017 v1.0” version in the “SNOMED CT International Edition” project, which can be found on the “IHTSDO Releases” page in MLDS, accessed here: 

https://mlds.ihtsdotools.org/#/ihtsdoReleases

3.3.4  Resource File location

The Stated Relationship to OWL resource file has been removed from the zip file containing the main release package, and is now available as a separate file to be downloaded from the same MLDS version as the International Release package.  This is available from the “January 2017 v1.0” version in the “SNOMED CT International Edition” project, which can be found on the “IHTSDO Releases” page in MLDS, accessed here: 

https://mlds.ihtsdotools.org/#/ihtsdoReleases

3.3.5  New refset added to the RF2 package

This refset is a "Lateralizable body structure reference set" (SCTID: 723264001), and has the following attributes:

• It is a Simple Refset 
• It can be used as a normal RF2 refset 
• It only shows concepts which have not yet been lateralised in SNOMED CT but which could be in future, and is not a complete set of Laterality concepts
• It will also be used by the RF1 conversion package in order to use the laterality content in the conversion to RF1 
• It has been added to the existing Simple Refset file in the International edition package (der2_Refset_SimpleSnapshot_INT_20170131.txt)

3.3.6  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

1. ...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 
2. ...files that just 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.

3.3.7  Early visibility of impending change in the July 2017 International edition

In 2009 the General Assembly decided that from April 26 2017 SNOMED International would no longer license the use of SNOMED antecedent works. See http://www.ihtsdo.org/snomed-ct/what-is-snomed-ct/previous-versions-of-snomed-ct.

In line with this decision, SNOMED International will stop publishing SNOMED RT codes for new SNOMED CT concepts after the January 2017 release. As of the July 2017 release, SNOMED International will also remove the SNOMED RT reference set (900000000000498005 |SNOMED RT identifier simple map (foundation metadata concept)|) from the Simple Reference set file in the International Edition.

SNOMED International again strongly urges users of these antecedent versions to migrate to SNOMED CT as soon as possible.  If anyone wishes to use the RT refset purely for migration purposes, SNOMED International will therefore host a static, non-maintained version (based on the January 2017 content) in a package to be hosted here in MLDS: https://mlds.ihtsdotools.org/#/viewReleases/viewRelease/5376