Most of us are using FHIR R4.
But how many of us are aware of the breaking changes between R4 and R5, not to mention R6?
Here’s an example.
The Media resource type that exists in R4 was removed in R5, replaced by the existing DocumentReference resource type.
This was a good move, as it consolidated common functionality into a single resource type.
Problem is, if you use R4 you may have no choice but to use the Media resource type. Not if you’re building your data model correctly.
You may say: “Media had a level 1 maturity in R4, it was always prone to change. You should have known better.”
Better than to use it?
Most reference elements (links to other resources) in FHIR are typed to specific resource types. A “subject” can usually only reference a Patient or a Group resource.
Likewise, the DiagnosticReport resource’s “media” element can ONLY reference a Media resource in R4. Using a DocumentReference resource here would fail validation.
Even with the best of intentions and careful selection of resources based on their maturity level it’s not always possible to “future proof” your FHIR implementation and application.
Not if you have a full and rich data model.
An argument could be made that data migration problems will not be that serious. And this may be true for anyone who has “rolled their own” FHIR façade.
But if you’re using a managed FHIR server, you’re going to have to pay a migration price eventually.
Changes between R4 and R5: https://hl7.org/fhir/R5/diff.html
Changes between R4 and R6 (so far): https://build.fhir.org/diff.html
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