FHIR is no magic wand. Without proper profiles, interoperability remains an illusion
Good FHIR profiles are the foundation of working interoperability. Marc van Aalten explains how to build them in five steps — using Advance Care Planning as an example.
By Marc van Aalten, Interoperability Expert at Interoplab
Imagine: a patient has made decisions about their end-of-life care. This is documented at their GP. But when they arrive at the hospital the next day, none of that information is visible. Not because the systems don’t exist — but because they can’t talk to each other.
FHIR is supposed to solve this. And it can. But only if the underlying profiles are well-designed. Adopting FHIR without good profiles is like building a highway without lane markings: technically present, but chaotic in practice.
Five steps to good FHIR profiles
1. Understand FHIR basics
FHIR works with Resources as building blocks (Patient, Observation, Procedure). Profiles let you customize those Resources for specific use cases. Extensions allow you to add information not found in the standard Resource model — but use them sparingly.
2. Define your use case
Before you write a line of code, you need to know what you want to exchange and why. Map the source data and the care process. Mindmaps help you structure complex relationships before diving into technical implementation.
3. Search for existing profiles
Nictiz publishes FHIR profiles based on ZIBs as the national standard. Simplifier.net offers an international overview. Always look first to see if a profile already exists that fits — or that you can adapt — before building something new.
4. Keep extensions minimal
Extensions are powerful but dangerous. Every extension you add makes the profile harder to implement and increases the risk of misinterpretation. Ask yourself: is this really necessary, or can I solve it differently?
5. Test and validate
Build test cases that cover both happy paths and edge cases. Use tools like Conformancelab to verify your profile works as intended across different implementations. Share your profile with other implementers and collect feedback.
A practical example: Advance Care Planning
Advance Care Planning (ACP) is a perfect use case for showing how profiles work in practice.
A patient documents their wishes:
- Who should be contacted in a crisis?
- What life-prolonging measures do they want?
- Where should their remains go?
This information needs to be documented once and be accessible across the entire care chain — from GP to hospital to nursing home.
Using FHIR, you create a profile for ACP Decisions. It references the Patient (who made the decision), the Practitioner (who documented it), and the DocumentReference (where the actual document is stored).
Without a good profile, each system interprets ACP differently. With a profile, they all understand: this is a DocumentReference with specific metadata, linked to a Consent resource that describes what the patient wants.
The bigger picture
Good FHIR profiles are not a technical exercise. They’re a prerequisite for trust in interoperability.
When you implement a standard without understanding the underlying profile, you’re making assumptions. Those assumptions often turn out to be wrong. When it’s too late, you’ve already spent months on implementation.
Invest in profile quality upfront. Test early. Validate against the official profile definition. Share your experience with other implementers.
That’s how you turn FHIR from a theoretical promise into a practical tool that actually works.
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