FHIR TL;DW: 6 Rules for Successful Interoperability Projects

In our FHIR TL;DW (Too Long; Didn’t Watch) series, we share bite-sized summaries and insights from key HL7 FHIR DevDays presentations.

FHIR interoperability is complex, but there are guiding principles that can help ensure success. In his DevDays talk, “Words of Wisdom for Interoperability Design,” Lloyd McKenzie, a globally recognized expert in healthcare modeling and design, shared six fundamental rules that shape successful interoperability projects. 

Developed from years of real-world experience, these rules provide crucial insights for anyone working on FHIR projects to help make better decisions and increase your chances of long-term success. Here’s a breakdown of Lloyd’s six interoperability rules—and an opportunity to contribute your own.

The 6 Rules of Interoperability 

1. Postel’s Law 

“Be conservative in what you do, be liberal in what you accept from others”. In other words, be careful to send out data that is compliant but be flexible when receiving data from others to maximize interoperability. 

2. The 80% Rule 

FHIR specifications should only include elements and features that most systems (80%) have the capability of handling, ensuring that standards remain broadly usable. Not to be confused with the Pareto Principle—20% of effort brings 80% of benefits. 

3. Fast, Interoperable, Cheap—Pick Two 

In any project, you can’t have all three—there will always be trade-offs. Understanding these constraints helps teams make better strategic decisions about what you can achieve with a particular set of resources for a project. 

4. Tesler’s Law (aka Law of Conservation of Complexity) 

No matter how well-designed a system is, some level of complexity will always exist. As Grahame Grieve, the father of FHIR, suggests, “You can move complexity around, but you can’t make it go away.” The key question is: where should that complexity live? 

5. Grahame’s Postulate 

“Interoperability is primarily a people problem, not a technical problem.” The most elegant technical solution means nothing if the people implementing it aren’t aligned and on board. Consensus, collaboration, and shared commitment are essential for advancing interoperability. 

6. Richel’s Rule 

“If you change the consensus group, you change the consensus.” If a small group makes a decision, but the broader community doesn’t agree, the effort will fail. When making decisions about interoperability, ensure that key stakeholders that you need buy-in from are involved early in decision-making to avoid costly rework later. 

Key Takeaways

Lloyd McKenzie concluded his talk with several big-picture insights about interoperability and standards development: 

• Words of wisdom and best practices are easy to throw around, but their true impact comes from carefully considering how they apply to real-world implementations.
• A long-term perspective is essential—rather than focusing only on immediate deadlines, organizations should think strategically about where and how they want to drive interoperability in the future.
• Stakeholder engagement is crucial—having the right people involved early in the process ensures smoother adoption and alignment. 
• Interoperability standards take time to develop—progress may be slow, but true interoperability requires moving the entire healthcare community forward, not just the technology itself.

What’s the 7th Law?

Lloyd has given us six key interoperability laws—but what about a seventh? 

Do you have a guiding principle or key lesson from your interoperability experience? Join the conversation and share your “7th Law” with the FHIR community!

Learn More From Firely

At Firely, we’re committed to sharing best practices and insights for everything FHIR. For more in-depth insights and discussions on navigating FHIR challenges, explore our blog and FHIR training courses. 

Interested in more talks like this? Join us and HL7 at the next FHIR DevDays, the largest FHIR-only event in the world where you can learn all about FHIR and hone your FHIR expertise. There’s plenty of content for both developers and non-coders, for FHIR starters and FHIR experts alike. 

To watch the full length video of Lloyd Mckenzie’s talk, you can find that here. For all videos from FHIR DevDays 2024, head over to the Devdays 2024 playlist on Youtube.