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Dispatch From The US Realm: January WGM Recap & Important News About The Future of US Core & FHIR Release 5

[fa icon="calendar"] Mar 4, 2024 11:29:52 AM / by HL7

Dispatch US Realm

By the US Realm Co-Chairs: Brett Marquard, Steve Posnack and Dan Vreeman, DPT

Greetings HL7 community, your US Realm Steering Committee co-chairs come bearing news. For the past few years, we have started to do a “state of the realm” recap for everyone at the January WGM. The full details are available here, but we wanted to celebrate and acknowledge some of 2023’s great work and what’s to come in 2024 through this post as well.



  • US Core will finalize USCDI v4 in May 2024, and then begin v5 design (in the fall).
  • C-CDA web publishing, using the FHIR StructureDefinition to support USCDI v4 (now) and then v5 (in the fall).
  • Now that ONC’s HTI-1 Final Rule is out and concrete dates are set, the industry transition from US Core 3.1.1 as a baseline to 6.1.0 is upon us. US Realm, in collaboration with other work groups, will be prioritizing its time to focus on supporting this migration. Please engage early and often this year as transition issues pop-up for you.

US Core and HL7 FHIR Release 5

For over a year, the US Realm has been evaluating the evolution of US Core and planning its future versions based on FHIR releases. This planning and transparency is essential for HL7 implementation guide (IG) authors to make informed choices about the FHIR release they choose to meet a particular use case. Given regulatory dates, industry implementation schedules, and the upcoming publication of FHIR Release 6 in the not-too-distant future, the US Realm voted at the January WGM to never publish a US Core implementation guide built on FHIR Release 5.

What’s This Really Mean?

First, this means that until HL7 FHIR R6 is published, IG authors within the US Realm can expect, with certainty, that the US Realm will continue to publish only FHIR R4-based US Core IG versions. We are closely tracking FHIR R6’s publication date and will provide more timing information in the future regarding the predicted release of the first FHIR R6-based US Core IG. Please also keep in mind that “authoring != implementation.” So even when there is a first version of an R6-based US Core IG, we expect a period where a parallel R4-based US Core IG is also published to support an eventual industry transition to R6.

Second, keep calm and carry on with R5-based IG authoring within the US Realm. We recognize that R4 may not always be able support new or expanded use cases and that R5 may offer the FHIR resources necessary to do so. That’s ok! If you’re supporting a specific use case that R5 works best for, go for it. At the same time, please be aware that industry-wide implementation is anchored to the R4-based US Core. As a result, if you have near-term use cases that are intended to be addressed using production implementations, especially those planning to leverage US Core profiles, we recommend that IG authors first look to use R4.

Topics: FHIR, C-CDA, ONC, USCDI, US Realm, US Core IG

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