📖 FHIR's 80/20 principle
Healthcare is too varied for one base data model to contain every detail needed by every country, specialty, organization, and project. FHIR therefore aims to provide a manageable common core that supports the requirements shared by many implementations.
This idea is often called FHIR’s 80/20 principle: focus the base specification on the relatively small set of requirements that covers a large share of common interoperability needs. It is a design principle, not a measured quota.
It does not mean that:
- every resource contains exactly 80% of all possible fields;
- only 80% of healthcare use cases can use FHIR; or
- the remaining requirements should be ignored.
FHIR handles context-specific requirements mainly through profiles
and extensions. For example, Patient.birthDate is optional in the
base Patient resource. A local profile can require it when a particular
workflow needs every Patient record to include a birth date. When the
base resource has no suitable element for a necessary concept, a
governed extension can represent that information.
The result is a shared base that systems can recognize, together with explicit local rules for the details that differ between use cases.