HL7FHIR (pronounced "fire") has become the dominant standard for exchanging electronic health care data worldwide. Created by Health Level Seven International (HL7), it represents a fundamental shift from earlier healthcare interoperability approaches toward modern, web-native APIs that developers can implement in hours rather than months. Mandated by regulators in the United States, Brazil, Israel, and other countries, FHIR is reshaping how patients, providers, and systems share clinical information.
Background
The initial concept for FHIR was published in August 2011 by Grahame Grieve under the working title "Resources For Health" (RFH). HL7 adopted the work item in September 2011 and the standard rapidly progressed through trial-use releases: DSTU1 (2014), DSTU2 (2015), STU3 (2017), Release 4 with the first normative content (2019), and Release 5 (2023). FHIR was explicitly designed to address the implementation complexity that hampered adoption of HL7 v2, v3, and the Clinical Document Architecture (CDA), combining the best features of those predecessors with a developer-friendly web architecture.
Purpose and Scope
FHIR defines a framework for healthcare data exchange built on RESTful HTTP, with data represented in JSON, XML, or RDF. The fundamental building blocks are "Resources" -- discrete, modular data objects representing clinical and administrative concepts such as Patient, Observation, Medication, DiagnosticReport, and Encounter. Resources can be retrieved and manipulated individually via their own URLs, offering a service-oriented alternative to document-centric approaches.
The standard also provides mechanisms for adaptation: Profiles constrain resources for specific use cases, Extensions add locally needed data elements, and Implementation Guides package profiles and guidance for particular domains. This design allows FHIR to serve contexts ranging from mobile phone health apps to national-scale data networks.
Key Resource Categories
| Category | Examples |
|---|---|
| Administrative | Patient, Practitioner, Organization, Location |
| Clinical | Condition, Observation, Procedure, AllergyIntolerance |
| Medications | Medication, MedicationRequest, MedicationAdministration |
| Diagnostics | DiagnosticReport, ImagingStudy, Specimen |
| Financial | Claim, ExplanationOfBenefit, Coverage |
| Infrastructure | CapabilityStatement, OperationDefinition, SearchParameter |
Serializations and Technical Formats
FHIR resources can be serialized in JSON (most commonly used in REST APIs), XML (traditional HL7 format), and RDF/Turtle (for linked data use cases). Each resource carries a human-readable XHTML narrative for clinical safety, ensuring that even systems that cannot process the structured data can display meaningful content to clinicians.
Governance and Maintenance
FHIR is developed and maintained by HL7 International through its FHIR Infrastructure and domain-specific Work Groups. The standard follows a mixed maturity model: individual resources and operations carry maturity levels from 0 (draft) to normative (N), allowing stable parts to be relied upon while others continue evolving through trial use. HL7 actively monitors implementations and incorporates feedback into subsequent releases.
Notable Implementations
In the United States, the 2020 CMS Interoperability and Patient Access final rule and the ONC 21st Century Cures Act Final Rule mandate FHIR-based APIs for Medicare, Medicaid, and health plan data exchange. Apple integrated FHIR into the iPhone Health app in 2018, enabling patients to view medical records from participating hospitals. Brazil's National Health Data Network (RNDS), launched in 2020, uses FHIR R4 for all national health information exchanges. Israel has undertaken a national FHIR adoption program through the FHIR IL community. Open-source implementations include HAPI-FHIR (Java), the SMART on FHIR framework, and reference libraries in multiple languages.
Related Standards
- SNOMED CT -- Clinical terminology widely used within FHIR resources for coding diagnoses, procedures, and findings
- ICD -- International Classification of Diseases, commonly mapped alongside FHIR for billing and epidemiological reporting
- HL7 CDA -- The Clinical Document Architecture that FHIR increasingly supplements or replaces for clinical document exchange