Subset

Subsets are an important resource in many implementations, grouping concepts in SNOMED CT that apply to a specific use case, like clinical specialties data entry, translations prioritization, data analysis, or others. The tools described in this section allow the implementers to create and maintain SNOMED CT subsets.

Subsets vs Reference Sets vs ValueSets

A subset of SNOMED CT concepts is a defined set of concepts taken from a wider set of concepts, in general from the complete terminology. 

Subsets in SNOMED CT are represented as Simple Type Reference Sets (Refsets), according to the RF2 specifications. The specifications support additional reference set patterns, that allow the users to represent more complex data structures, including additional columns beyond the simple membership to the set.

In HL7 FHIR specifications, subsets are presented as ValueSets. A ValueSet resource instance specifies a set of codes drawn from one or more code systems, intended for use in a particular context. 

In the context of a SNOMED CT Implementation, the requirement to create subsets can be satisfied by tools that create any of these components, generic subsets with custom formats, standard RF2 reference sets, or HL7 FHRI ValueSets. The choice of tooling depends on the requirements of other components of the implementation project, especially the terminology server that will be used to provide access to the subsets. 

SNOMED Internacional Reference Set and Translation Tool

This tool is maintained by SNOMED International and is used to maintain Reference Sets and Translations for many national extensions.

The features related to Refset Authoring tasks include:

• Creation of Extensional and Intensional Simple Type Reference Sets
• Adding members by direct selection, by uploading flat files, or by specifying queries
• Maintenance tasks related to the update to new releases of dependencies
• Collaborative workflow for content revisions
• Refset export for publication
• Management of refset metadata
• Refset directory

Other Subset tools

• ART ValueSet Editor
  • https://art-decor.org/mediawiki/index.php/ART_Value_Set_Editor
• clinFHIR ValueSet Editor
  • http://clinfhir.com/valuesetCreator.html
• HealthTerm, CareCom
  • https://www.carecom.com/products/#healthterm
• Snow Owl collaborative terminology authoring platform, B2i
  • http://b2i.sg/
• termSpace collaborative authoring environment, termMed
  • http://www.termspace.com/landing/index.html
• Trifolia ValueSet Editor
  • https://www.lantanagroup.com/our-software-products/trifolia-on-fhir/