NucLexNuclear Medicine Lexicon and Theranostics Ontology
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Lexicon · Mathematical and computational foundations

Lexicon entryDraftNX-C019

Value set

Fully specified name: Value set (concept)

A selection of codes intended for a particular use or context.

Scope note
A value set may draw on multiple code systems and depend on their versions.
Synonyms
None recorded as true synonyms in this context.
Monograph
FHIR terminology resources (draft)
External mappings
None recorded. In W0 no mapping to SNOMED CT® or any external authority is asserted for this entry. A future mapping record will carry source system, identifier, version, relation type, evidence, author, confidence where meaningful, and review state.
Formal status
Editorial entry only. It is not part of any released ontology and a prose edit here changes no formal definition.

Draft. This entry is an unreviewed draft. Its sources have not been checked by a named person and no domain reviewer has approved it. Treat every claim as provisional.

Notes

A value set is a list of codes chosen for a purpose: the codes a field may contain, the codes that define a cohort, the codes a report should group together. In FHIR (Fast Healthcare Interoperability Resources) the ValueSet resource describes such a selection either by listing codes explicitly (an extensional definition) or by stating rules over one or more code systems, such as "all descendants of this concept" (an intensional definition). A terminology server can expand an intensional value set into its explicit members at a given point in time.

The scope note identifies the two properties a user most often overlooks. First, a value set may draw on several Code system authorities at once; a set of "radiopharmaceutical administration" codes might combine procedure codes from one system with substance codes from another. Second, an intensional value set depends on the versions of the code systems it references. A rule that selects descendants of a concept yields different members after the code system is updated, so a cohort defined by a value set is not stable unless the versions are pinned.

For a physician or researcher the practical lesson is that "the codes for X" is never a complete specification without the code systems, their versions, and the date of expansion. The FHIR R5 ValueSet page is the authoritative reference.

Sources consulted (1)
  • https://www.hl7.org/fhir/R5/valueset.html