1 Introduction

The SNOMED CT to Orphanet equivalency table is a product of an ongoing programme of work carried out under a pre-existing collaboration agreement between INSERM and the International Health Terminology Standards Organisation (IHTSDO). The work commenced in May 2014 and the first joint release of the candidate baseline equivalency table took place in April 2015, for review and feedback.

2 Background

The overarching aim of the collaboration agreement, first established in 2010 and updated in September 2014, was to advance terminology harmonisation and foster interoperability in health information systems. Joint work would build on previous efforts, culminating in joint publication of: 

a) An equivalence table between Orphanet® and SNOMED Clinical Terms (SNOMED CT®) for rare diseases

The initial effort centred on nursing diagnoses, specifically problems – the focus of this release document. Other related work includes the identification of SNOMED CT equivalencies for Orphanet nursing interventions and in the future Orphanet positive nursing diagnoses (i.e. goals or expected outcomes).

3 Motivation

The Orphanet, a product of the INSERM, is a terminology that enables nurses to describe and report their practice in a systematic way. The resulting information is used to support care and effective decision-making, and to inform nursing education and health policy. 
SNOMED CT is the most comprehensive and precise clinical health terminology product in the world, owned and distributed around the world by The International Health Terminology Standards Development Organisation (IHTSDO). 
The equivalency table is intended for use by nurses, and other interested professional groups. Robust systems and processes within INSERM and IHTSDO assure the integrity of both terminologies. 

As Orphanet is intended for use by and for nurses, INSERM has been able to focus attention on the development of Orphanet specifically for nursing practice. This has resulted in a rich and comprehensive resource that nurses can use to describe and report in detail the things that they assess (diagnoses e.g. nausea) and the things that they do (interventions e.g. counseling). The potential benefits of a consistent approach to capturing nursing data are far-reaching. However, nurses do not practice in isolation, they practice alongside many other disciplines. One of the potential risks of a specific nursing-focus is that nursing will be somehow disconnected from a larger health information landscape. 

The table of equivalents provides a vehicle for transforming Orphanet-encoded data into SNOMED CT (e.g. an Orphanet concept in a local system can be transformed via the table to the equivalent SNOMED CT concept for use in a multidisciplinary record). By providing a robust pathway from Orphanet to SNOMED CT, the table of equivalents helps to ensure that users of Orphanet can continue to use their preferred terminology while remaining a central part of the bigger picture and wider implementation of SNOMED CT globally.

4 Design

Decisions concerning source concepts, target concepts and validity of equivalencies were made by consensus of all parties (INSERM, IHTSDO, etc). The SNOMED International Nursing Derivatives Editorial Group now provides international validation of the content included in the set prior to publication with each release.

4.1 Versions

The version of Orphanet used is the May 2017 release.  

The version of SNOMED CT used is the July 2018 International Release.

4.2 Source

The source is a subset of 852 Orphanet concepts.

4.3 Target

All target concepts are drawn from SNOMED CT Clinical Findings and Situation. As part of the work, new concepts were identified as relevant and needed within SNOMED CT. These were modeled as Clinical Findings.

4.4 Direction

The direction is from SNOMED CT International Release to the Orphanet classification in line with the stated use case in section 3.

4.5 Cardinality

The cardinality for all equivalencies in the table is one-to-one.

5 Content

The SNOMED CT to Orphanet equivalency table covers just one semantic type – nursing diagnoses (problems) – with equivalent Orphanet and SNOMED CT concepts for each problem. The table comprises 529 active equivalencies, representing a subset of Orphanet and a subset of SNOMED CT – equivalencies have not been identified for all Orphanet diagnoses, or for all SNOMED CT Clinical Findings. 

5.1 Changes for the July 2018 release

As a result of changes made to the July 2018 release of SNOMED CT, there were 0 Orphanet codes for diagnoses which were removed from the table.

The following members have been removed from the equivalency table:

6 Obtaining the equivalency table

The equivalency table was released in April 2015 as a technology preview/candidate baseline and has subsequently been maintained according to the release schedules of Orphanet and SNOMED CT. The baseline release of the equivalency table was released after July 2015, following agreement between INSERM and IHTSDO. 

Access within IHTSDO member countries is provided by the Member National Release Centre in each country, via the relevant Member page. Affiliates of IHTSDO in non-member countries can access the table through their Member Licensing and Distribution Service (MLDS) account. Please contact info@snomed.org for more information if required. 

The equivalency table is available for download from the Orphanet website: 
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Users of the table should comply with licensing arrangements for both Orphanet and SNOMED CT.

7 Feedback

Feedback should be sent jointly to info@snomed.org and aamherdt@uwm.edu. Feedback should include any issues relating to implementation, suggestions for future content inclusion or general comments regarding the subset.

8 Technical Notes

RF2 package format

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.