FHIR valueset Page

Welcome to "ValueSet" discussion page. Please put any comments about this page here. Contents will be reviewed periodically.

NICTIZ, ART DECOR input

Suggested changes to FHIR resources

• ValueSet.description -> looking for a way to make this multi-language (example: epSOS valuesets). Shouldn't need multiple instances of a valueset (with the same codes) just to be multi-language.
  • GG: well, wouldn't that apply to name as well? Is there a real use case for this? How many value sets will get multiple descriptions? (agree not to have multiple instances - would be an extension)

• ValueSet.identifier -> how does this relate to the URL identifier for a ValueSet? E.g. When we use http://hl7.org/fhir/valuesets/body-site, is the identifier "body-site" by convention? If companies having valueset repositories merge, what happens to the references? Are we always using the identifier (no problem) or the actual URL reference (might change and then result in duplicates/clashes).
  • GG: I think that the identifier is the thing that is stable and the target of a reference from a coded value. The literal URL is too unstable (i.e. when repositories merge!). I will document this better if there's agreement

• ValueSet.version -> should be a timestamp, why not make it "instant"
  • GG: huh? how can it be an instant? All the snomed value sets have granularity of day, I don't think we can force it past that

• ValueSet.date -> rename to functional name like "statusChanged"
  • GG: well, really? how any other ways could you read date?

• ValueSet.expansion.contains also needs an "abstract" element.
  • GG: well, the notion is that it's abstract if there's no code. Code system used to be like that, but ended up needing code for abstract concepts (v3, yay). Does an expansion have a use case for this?

• ValueSet.expansion.contains why is system not 1..1 (compose & define have system 1..1)? Is that for "just" returning display, not code/codesystem? Should there then not be a rule that IF a code is given, the system is 1..1
  • GG: yes, if there's no code, there might just be a label for a category that has no formal meaning. So no system too. Agree that there should be an invariant about this

• ValueSet.Compose.Include is used for both inclusion and exclusion criteria. Would "Selection", "Codes", "CodedConcepts" or "ConceptCollection" be a better name?
  • GG: how about "Rules"?

• Suggestion to add elements for CTS2 "official release date" and "expiration date".
  • GG: well, what are their definitions?

• Were IHE SVS1, SVS2 and DECOR valuesets (extension of SVS1) considered, instead of introducing a new ValueSet resource?

• Suggestion to rename valueset status "testing" to "experimental", because "testing" can cause confusion with IHE's "DSTU" testing phase.

ValueSet ART DECOR/FHIR comparison

• status codes:
  • cancelled (=withdrawn)
  • deprecated (=superseded)
  • draft (=draft)
  • final (=production)
  • new ("to become draft, do not look at yet, alpha version")
  • rejected (=withdrawn)
  • Not in DECOR: testing
  • Not in DECOR: review
    • GG: is the difference between new and draft useful?

• dates
  • effectiveDate (more or less the creation date, may be changed but is used to reference this version, maps to "version" in FHIR)
  • officialReleaseDate (not currently used)
  • expirationDate (not currently used)
  • Generally speaking: FHIR traces last status change, so e.g. after going "superseded", the date of publication is lost. There's one "date".
    • GG: yes, this is a good point. Suggestions?

• ValueSet composition
  • Inclusion/exclusion by means of "all", "descendant", "system", "children", not supported by DECOR for lack of usecases.
    • GG: we use "system". The use case is pretty straightforward. I'm not sure about the difference between "all", "descendent" and particularly "children", but we need at least one of all and descendent - all codes subsumed by another code is definitely a use case.
  • Generally speaking: not enough to cover CTS2, but too much for the FHIR practical principles.
  • Only usecase is valueset composition: set of coded concepts from one or more codesystems, existing valueset + new coded concepts, existing valueset + nullflavors
    • GG: ? - don't understand the last two

Suggested changes to FHIR Profile resources

• ValueSet and Resource metadata (status, notably) is modelled differently, why?
• Constraints on elements are expressed using ocl/xpath, but for common constraints (like unit, currency, min/max value etc) this is more complex than necessary, so here, to adhere to FHIR principles, the simple cases should become simple, so introduce specific constraints for: unit, currency, minInclude, maxInclude, fractionDigits, minLength, maxLength, value (see ART DECOR element/property).

Profile ART DECOR/FHIR comparison

• DECOR always inlines the binding in the element definitions, why is this a separate structure in Profile for FHIR?