Stream: terminology
Topic: URI for VSAC hosted Value Sets
Mary Dobbins (Nov 17 2021 at 21:10):
We're implementing US Core 4 and wondering what to use as the URI for value sets hosted by VSAC. Is there a designated strategy?
Bryn Rhodes (Nov 17 2021 at 22:51):
The base canonical is set by VSAC, so here's an example: http://cts.nlm.nih.gov/fhir/ValueSet/2.16.840.1.113883.3.526.3.1240
Mary Dobbins (Nov 18 2021 at 14:58):
@Bryn Rhodes Do I have to use REST API to find this? Is it as simple as using the name space http://cts.nlm.nih.gov/fhir/ValueSet/ with the value set OID? Thanks for your help, Bryn.
Bryn Rhodes (Nov 18 2021 at 15:11):
Yes, use that canonical base with the value set OID and that is the canonical URL for the ValueSet. The great thing about that is that because of the way VSAC publishes their FHIR API, it is _also_ the resolveable URL for the ValueSet, if you just click the link it will take you there (you need to provide your VSAC API Key).
Mary Dobbins (Nov 18 2021 at 19:10):
Yes, got it, thanks much, Bryn!
Robert McClure (Nov 20 2021 at 01:50):
One word of caution: That cts standard structure is true for all value sets you obtain from VSAC. Sometimes VSAC includes a value set that was defined someplace else and as of this moment, they have ignored the other canonical url. It is my understanding they plan to support replicating the non-VSAC url sometime in the future but for now, when they do this they are in essence creating there own value set that is a clone.
That sounds more concerning than it is because VSAC users must assume that if you find the value set in VSAC, VSAC is the source of truth, but that assumption is dangerous over the long term.
Eric Haas (Nov 22 2021 at 15:19):
We provided some documentation around using vsac here for US Core. Was that not helpful?
Robert McClure (Nov 22 2021 at 18:51):
@Eric Haas , sure that is helpful. But the issue I'm raising has to do with situations where a value set with the same name, same content, shows up in multiple places and one of them is VSAC. And when VSAC starts hosting other value sets, we need to make sure it all works correctly. So far, particularly given the way we decided to handle the aligned C-CDA-USCore approach to race-ethnicity, gender identity, and particularly birth sex there could have been a problem. But we found a way around it.
So no need to make changes to the text you reference for now.
Last updated: Apr 12 2022 at 19:14 UTC
