Interoperability

Key facts

Statutory definition

21st Century Cures Act (2016), Section 4003

Core U.S. data set

United States Core Data for Interoperability (USCDI)

Main API standard

HL7 FHIR

National exchange framework

Trusted Exchange Framework and Common Agreement (TEFCA)

What is interoperability?

The 21st Century Cures Act defines interoperable health IT as technology that enables secure exchange and use of electronic health information from other health IT without special effort by the user, allows complete access to all electronically accessible health information for authorized uses under law, and does not constitute information blocking.

Moving a file is not enough. Systems are interoperable only when the receiver can interpret the data correctly, for example recognizing that a lab result, medication or diagnosis means the same thing in both places.

Federal policy pushes interoperability from several directions. Certified health IT must support USCDI data elements and FHIR APIs, CMS rules require many payers to offer FHIR-based APIs, TEFCA sets a nationwide network of networks, and information blocking rules penalize unreasonable interference with data access.

Levels of interoperability

A widely used model describes four levels:

• Foundational: one system can send data to another, even if the receiver cannot interpret it.
• Structural: data follows a shared format, such as HL7 version 2 messages, C-CDA documents or FHIR resources.
• Semantic: both sides use shared vocabularies, such as LOINC for lab tests, SNOMED CT for clinical findings, RxNorm for drugs and ICD-10-CM for diagnoses.
• Organizational: governance, consent policies and trust agreements let exchange happen across organizations.

Why interoperability matters

Gaps in interoperability show up as cost, delay and missing data:

• Care coordination: hospitals send admission, discharge and transfer notifications so primary care teams can follow up.
• Value-based care: organizations in risk contracts depend on exchanged clinical data to manage quality measures and costs.
• Health IT and AI products: standardized FHIR APIs reduce the custom interface work needed for each new EHR customer.
• Data analysis: shared vocabularies and identifiers such as the NPI and NDC make it possible to join clinical, claims and reference data.