FHIR Versioning and How To STILL Stay Up To Date

The world has changed a lot since December 19, 2019, when 1upHealth published the first “version” of this post, FHIR® Versioning and How to Stay Up To Date. What throws me the most? A cohort of students have been through four years of high school or college completely.

Over the course of the last four years, the available FHIR versions have also changed, and they will continue to evolve for the foreseeable future. The purpose of this post is to explain the new developments of the standard, but first I want to level set around FHIR, FHIR versions, and the history of FHIR standards.

What is FHIR and what are “FHIR versions”? 

As we covered in the 2019 blog, in healthcare, many data standards are set by HL7. The process of creating and releasing a new standard is challenging, due to variability in protocol standardization that often encompasses multiple versions and various use cases across different constraints. In an attempt to solve this problem, HL7 introduced FHIR® (or Fast Healthcare Interoperability Resources) in 2012. 

FHIR is built around “resources,” which are modular components that enable patients and doctors to quickly and easily access discrete data. While FHIR is providing a modern form of healthcare interoperability based on modern web technologies, there are some drawbacks around versions and inconsistent implementation methodology. The FHIR standard is continuously evolving. It’s not always easy for organizations to stay up to date. Here’s a look at the history of different versions of FHIR.

FHIR Version History: A Primer

Back in December 2019, when the last blog was written, DSTU2, STU3, and R4 were the most relevant FHIR versions in use, and all services at 1upHealth supported these three formats. 

FHIR DSTU2, which stands for Second Draft Standard for Trial Use, was released October 24, 2015 with various updates from the original DSTU1, encompassing addition and removal of elements, updates to code elements, status, and more. 

FHIR STU3, which stands for Release 3 Standard for Trial Use, was released February 21, 2017 and encompassed over 2,400 changes. Examples of updates included version management consolidation, improvements to resource definitions, technical changes to RESTful APIs, and more. 

FHIR R4, or Release 4, was finalized on December 27, 2018. R4 has normative content, meaning that some resources and attributes will not change (where earlier versions of the standard were more flexible, with breaking changes between versions).

At the time of its release, we predicted R4 would be revolutionary because adoption of R4 promised a true, consistent standard and viable interoperability. Examples of what was added as part of FHIR R4 were new elements like age, address, annotation, dosage, money, booleans, and more – all of which further expand the amount of data able to be queried.

FHIR: Still Championing Interoperability

Our initial prediction about FHIR R4 being revolutionary? Spot on. It’s now the de facto standard, powering everything from the 2020 CMS Patient Access API to the new CMS Payer-to-Payer and Provider Access API regulations kicking in by 2027. Why? FHIR’s modular resource approach enables seamless data exchange across diverse systems, a crucial step in improving care delivery and unlocking the power of health information.

But innovation marches on. FHIR is a living standard, continuously evolving with feedback-driven releases that expand its capabilities. While earlier versions laid the groundwork, today’s key players are:

FHIR R4: Stable & Established (think reliable workhorse)

  • Released: November 2019
  • Resources: ~150 core, 200+ extensions
  • Stability: Widely adopted, mature resources
  • Great starting point for most


FHIR R4b: Testing & Improvement (think beta tester)

  • Released: December 2022
  • Resources: Minor changes to R4, few new niche resources
  • Stability: Less stable than R4, intended for early adoption
  • For early adopters and specific needs


FHIR R5: New Frontiers (think explorer)

  • Released: March 2023
  • Resources: 55+ new resources across various areas
  • Stability: Trial use only, not production-ready
  • Major update, a glimpse of the future


FHIR R6: Coming Soon (think next big thing)

  • Status: Under development, expected 2024
  • Resources: Building on R5, aiming for stability
  • Stay tuned for the future of FHIR!


The Rise of FHIR as the Interoperability Champion

Since its introduction, FHIR has become the undisputed leader in healthcare data interoperability. Its modular, flexible, and standardized approach has resonated across the country (and the world), leading to widespread usage and standardization.

The Future is Interoperable

Continuing widespread adoption of FHIR promises a future with seamless data exchange and improved utilization of clinical data. This will require robust collaboration between healthcare stakeholders to ensure ongoing development and consistent implementation. 

Evolving versions of the FHIR standard provide a critical framework for this interplay and understanding the details and nuances of each version is crucial so as to choose the right tool for the job. In the same way that decisions around FHIR R4 in 2019 are continuing to impact payers and providers today, tomorrow in preparation for 2027, and beyond 2027 as the new regulations go live, the choices you make today may persist and reverberate for the next decade or more. So be smart, choose wisely, and let’s keep pushing to make true interoperability a reality.

For more information on FHIR fundamentals, use cases, and 1upHealth’s role in FHIR:

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