Procedure.usedCode is listed as Must Support to enable reference to a Codeable Concept that was used during the procedure and it was previously recommended to address a type of device placed during a procedure. However, during discussion Monday Q4 during the May 2022 WGM with OO and CQI, the consensus opinion recommended use of usedReference since it specifically allows reference to another resource and enables further detailed expression of the resource element rather than merely a code. The current example for use is to provide exclusive feeding with human breast milk and Procedure.usedReference referencing Substance would allow more direct expression of the information required. The usedCode would only allow a specific code from a value set or a direct reference code, but without further detail about the item/substance used. Further, the referenced Device, Medication, and Substance should be QICoreDevice, QICoreMedication, and QICoreSubstance.

Note - in FHIR R5, the concept is merely .used which can be a codeable concept or a reference. The reason the usedCode and usedReference are individually defined in FHIR R4 was a tooling limitation that only allowed 1 datatype per element, something that changes in FHIR R5. Therefore, could consider removing Must Support for reasonCode but it is more appropriate to keep it there as well as adding Must Support to reasonReference.