Stream: terminology
Topic: Handling change from hl7.org/fhir/v3 to terminology.hl7.org
Elliot Silver (Aug 26 2021 at 22:43):
I'm working with an organization that has published numerous value sets (represented both as FHIR ValueSets, as well as in other forms) containing codes from HL7 v3. Many of these value sets are quite old, and date back to before THO.
Now that all the CodeSystems have moved to THO, what is best practice for updating the value sets? Should they continue to use code system canonical urls of the form hl7.org/fhir/v3/..., or should they be updated? What advice should we give to our user community in terms of how they handle existing data (is http://hl7.org/fhir/v3/AcknowledgementCondition#AL the same value as http://terminology.hl7.org/CodeSystem/v3-AcknowledgementCondition#AL? Does HL7 have mappings we can point users to? (I know the mapping is trivial, but using a mapping would mean that they handle this change, the same as they handle converting from a local code to any standard terminology? What advice have other organizations given to their users? What have other organizations done internally?
Alternatively, what is the downside to staying with the old code system canonicals? The canonical won't resolve, but canonicals aren't required to. What else?
Thanks.
Rob Hausam (Aug 27 2021 at 14:50):
@Elliot Silver Using your example, in FHIR R4 and beyond the official canonical url for the v3 AcknowledgementCondition code system is http://terminology.hl7.org/CodeSystem/v3-AcknowledgementCondition - so to be FHIR conformant you must use that url in Coding.system and in ValueSet.compose.include.system. And in STU3 for those same elements you must use http://hl7.org/fhir/v3/AcknowledgementCondition. Apparently we don't have NamingSystem resources for translating these canonical identifiers in THO, but I think we could consider that. @Ted Klein?
Ted Klein (Aug 27 2021 at 22:12):
I agree with your recommendations. In addition, note that any new codes or changes to existing codes will ONLY be applied to the source of truth in THO; the older copies of v3 content in the older FHIR specs (URL based in hl7.org/fhir/v3/...) are essentially frozen past history snapshots and no longer actively maintained. As far as the NamingSystem resources go, the update to the THO UI layout that more clearly shows the provenance and history of URLs that particular code systems have been published with in the past will be more obvious; although these are persistent in NamingSystem resources, they will be named "Technical Identifiers". At this time we only have official policy for creating these for external (non-HL7) terminology resources, but I suspect we will need to extend this to the HL7 ones.
Last updated: Apr 12 2022 at 19:14 UTC
