UK Terminology Centre (UKTC)
SNOMED CT, READ2 & CTV3 code usage
GP Connect systems are expected to handle coded data as follows:
- Data originally entered into a system using the preferred system (i.e. SNOMED CT)
- SHALL be returned as SNOMED CT. The SNOMED CT DescriptionID should be included in addition to the ConceptID where available. The DescriptionID can convey a different meaning to the ConceptID due to the difference in the specific wording used for the two codes.
- If no suitable code exists in the value set (i.e. if only text is available, then just text MAY be used).
- Data originally entered into a system using an alternate coding system (i.e. READ2 or CTV3)
- SHALL be returned in the code system it was originally entered in (i.e. READ2 or CTV3) AND
- SHALL also be returned as a preferred code (i.e. SNOMED CT) if a valid mapping/alternate code exists (i.e. there is a NHS Digital assured READ2 or CTV3 to SNOMED CT mapping in place).
Assured mappings can be found in the NHS Data Migration download.
Case sensitivity of terminologies
Throughout this specification, coded values are always treated as a pair composed of “system” and “code”, where the system is a URL that identifies the code system that defines the codes. Note, that system values are always case sensitive. Different code systems make their own rules as to whether the codes they define are case sensitive or not. Note that all the codes defined by FHIR itself are case sensitive and SHALL be used in the provided case (usually, but not always, lowercase).