FHIR (Fast Healthcare Interoperability Resources) integration enables healthcare systems to exchange structured clinical data in real time using a globally standardized API framework defined by HL7 (Health Level Seven International) [1]. Instead of building custom point-to-point interfaces between systems, FHIR provides a shared data model based on modular Resources that all compliant systems can interpret consistently [1,2].
In modern clinical ecosystems, three standards typically work together:
- FHIR for clinical data exchange [1]
- SMART on FHIR for secure application launch and authorization within EHR workflows [4]
- FHIRcast for synchronizing clinical context across multiple applications in real time [5]
Together, these standards form the foundation of interoperable digital healthcare environments and support scalable clinical application ecosystems [2], can reduce duplicate work, improve interoperability and allow clinicians to access the right information without switching between disconnected systems.
What is FHIR?
FHIR is the HL7 international standard for healthcare data exchange, designed to enable interoperable, web-based communication between healthcare systems [1].
FHIR is built around modular components called Resources, each representing a clinically meaningful concept such as:
- Patient
- Observation
- DiagnosticReport
- ImagingStudy
- Medication
- Procedure
Each Resource follows a consistent structure, enabling standardized interpretation across systems [1,2].
For clinicians, this means information can be exchanged more reliably between:
- Electronic health records
- PACS and imaging viewers
- Laboratory information systems
- Pathology systems
- Clinical decision support platforms
- AI applications
- Research databases
- Patient portals
FHIR has evolved through multiple releases. R4 is the most widely adopted version, and HL7 is preparing R6 as the next release, with the full specification balloted as a normative standard [6,10–14].
FHIR’s design principle is summarized by HL7 as enabling implementation “without sacrificing information integrity” while reducing integration complexity [1].
How FHIR Connects Clinical Systems
FHIR replaces fragmented system-to-system interfaces with a unified API-based communication model.
A useful analogy is to think of FHIR as a universal medical language spoken by software. Without FHIR, every healthcare application requires its own custom translation for every other system. With FHIR, applications speak the same standardized language.
FHIR enables:
- Standard API requests (RESTful)
- Structured JSON/XML clinical resources
- Reusable integration logic across systems [1,2]
A simplified workflow looks like this:
- A clinician opens a patient record
- The EHR queries FHIR APIs for structured data
- Imaging, lab, pathology, and external systems respond with standardized resources
- Applications display synchronized clinical context
- New observations can be written back into the record via FHIR APIs [1]
This model reduces redundant data entry and improves cross-system consistency [2]. Instead of manually copying information between systems, the data moves automatically in a standardized format.
Why FHIR Matters in Clinical Practice
Although FHIR is a technical standard, its value is primarily clinical. Interoperability frameworks are widely regarded as a prerequisite for digital medicine [7]. They can improve:
- information accessibility at the point of care
- continuity across care settings
- reduction of redundant testing and documentation
- integration of decision support systems
FHIR specifically supports:
- multimodal data integration (imaging, labs, pathology, genomics)
- longitudinal patient views
- cross-institutional collaboration
- AI-assisted clinical workflows [7,9]
What is SMART on FHIR?
SMART on FHIR extends FHIR by enabling secure, standardized launch and authorization of third-party clinical applications inside EHR environments [4].
It is built on widely adopted security standards (OAuth2/OpenID Connect) and allows applications to:
- authenticate users securely
- access patient context automatically
- respect role-based permissions
- run across different EHR systems without reimplementation [4]
A key design goal is application portability across healthcare systems, enabling a “write once, run anywhere” model for clinical software [4].
Why SMART on FHIR matters
Every new clinical application has traditionally meant its own integration project: a custom interface, a firewall and account setup, a test cycle, and then a connection that has to be maintained and re-validated whenever either side is updated. SMART on FHIR replaces this with a single mechanism the EHR already provides. Applications register against the existing FHIR endpoint and authenticate through OAuth2/OpenID Connect, so there is no per-application interface to write or maintain. IT keeps control over what is approved, which scopes are granted, who may use it, and can revoke access centrally.
In practice this changes which tools are realistically available to clinicians. When every application requires its own integration project, requests for a specialized tool compete for the same limited IT capacity, and narrow ones rarely win. A tool for a single indication or a rare disease is hard to justify against the same integration effort as a department-wide system. With a standardized launch mechanism, that effort is much smaller, so small and highly specialized applications become practical to deploy. It also means these applications open from within the EHR with the patient already in context, using the existing login and permissions.
What is FHIRcast?
While SMART on FHIR enables secure application launch, FHIRcast ensures real-time synchronization of clinical context across multiple applications.
FHIRcast defines a publish/subscribe model where applications share:
- active patient context
- selected imaging study
- clinical encounter state
This prevents workflow fragmentation when multiple tools are used simultaneously [5].
FHIRcast is particularly relevant in environments where clinicians work across:
- imaging viewers
- reporting systems
- EHR platforms
- AI-assisted analysis tools
Without synchronization, each system would require independent patient selection, increasing cognitive load and error risk [5].
Why FHIRcast matters
Every additional application on the workstation usually means selecting the patient again for each case. Across a full worklist those seconds add up, and they are usually what decides whether a genuinely useful tool is used or quietly dropped after a few weeks.
FHIRcast eliminates this step. When a radiologist opens the next study in the PACS worklist, the applications subscribed to that session, such as the reporting system, an analysis tool or the EHR view, switch to the same patient and study on their own. The patient is selected once and the subscribed applications follow every context change for the rest of the session.
Because context synchronization is defined as an open standard rather than a vendor-specific mechanism, this also applies to applications from different suppliers working side by side.
FHIR vs SMART on FHIR vs FHIRcast
| Standard | Role in Clinical Ecosystem |
|---|---|
| FHIR | Standardizes healthcare data exchange [1] |
| SMART on FHIR | Enables secure app launch and authorization inside EHRs [4] |
| FHIRcast | Synchronizes clinical context across applications in real time [5] |
Together, they form a layered interoperability architecture [1,4,5].
Clinical Value Across Medical Disciplines
Interoperability needs are universal in modern medicine because care increasingly depends on multi-source data integration.
FHIR enables structured access to:
- diagnostic imaging data
- laboratory results
- histopathology reports
- genomic and molecular data
- medication histories
- longitudinal care pathways
Standardized data exchange supports communication between care teams and the pooling of data across institutions, which can make multidisciplinary decision-making more efficient [7].
FHIR and Artificial Intelligence in Healthcare
FHIR has become a foundational enabler for clinical AI systems because it provides:
- structured, standardized datasets
- vendor-neutral access to clinical data
- scalable integration across institutions
This reduces the need for custom data pipelines for each hospital deployment [2,7].
Recent digital health literature emphasizes that standardized interoperability frameworks are essential for safe and scalable clinical AI adoption [7,8].
Find out why interoperability matters, what stands in its way, and how FHIR and AI are shaping the future of healthcare in our interview with Johannes Kast, Mint Medical’s Director of Research and Development, available to read or watch: Systems on FHIR: Driving Healthcare Innovation Through Interoperability.
Frequently Asked Questions
Is FHIR Replacing Existing Systems?
No, FHIR is generally not a replacement for EHRs, PACS, laboratory systems, or hospital information systems. Instead, it functions as an interoperability layer above existing infrastructure, enabling integration without full system replacement [1].
Is FHIR widely adopted in healthcare?
Yes, adoption is increasing globally, particularly in regulatory-driven markets where interoperability requirements are mandated [3,9].
Is FHIR secure enough for clinical use?
FHIR relies on established web security standards (TLS, OAuth2, OpenID Connect) and is typically implemented with additional governance layers such as SMART on FHIR authorization frameworks [4].
What problem does FHIR solve?
FHIR addresses the long-standing challenge of heterogeneous healthcare systems lacking a shared data model, which has historically limited interoperability and data reuse [2].
References
[1] HL7 International. FHIR Release 5 Specification (R5). https://hl7.org/fhir/
[2] Mandel JC, Kreda DA, Mandl KD, Kohane IS, Ramoni RB. SMART on FHIR: a standards-based, interoperable apps platform for electronic health records. Journal of the American Medical Informatics Association. 2016;23(5):899–908. https://doi.org/10.1093/jamia/ocv189
[3] Centers for Medicare & Medicaid Services (CMS). FHIR and Interoperability Overview. https://www.cms.gov/priorities/burden-reduction
[4] HL7 International. SMART App Launch Framework (SMART on FHIR). https://hl7.org/fhir/smart-app-launch/
[5] HL7 International. FHIRcast Implementation Guide. https://fhircast.hl7.org/
[6] HL7 International. FHIR R6 Snapshot (Sept 2026) https://hl7.org/fhir/6.0.0-snapshot1/foundation-module.html#roadmap
[7] Lehne M, Sass J, Essenwanger A, Schepers J, Thun S. Why digital medicine depends on interoperability. npj Digital Medicine. 2019;2:79. https://communities.springernature.com/posts/52522-why-digital-medicine-depends-on-interoperability
[8] Topol EJ. High-performance medicine: the convergence of human and artificial intelligence. Nature Medicine. 2019;25:44–56. https://doi.org/10.1038/s41591-018-0300-7
[9] Ayaz M, Pasha MF, Alzahrani MY, Budiarto R, Stiawan D. The Fast Health Interoperability Resources (FHIR) standard: systematic literature review of implementations, applications, challenges and opportunities. JMIR Medical Informatics. 2021;9(7):e21929. https://medinform.jmir.org/2021/7/e21929
[10] gematik GmbH, Kompetenzzentrum für Interoperabilität im Gesundheitswesen (KIG). Verwendung von FHIR in Deutschland [Use of FHIR in Germany]. INA – Interoperabilitäts-Navigator. https://www.ina.gematik.de/iop-themenwelten/nationale-internationale-entwicklungen/verwendung-von-fhir-in-deutschland
[11] HL7 Europe. HL7 Europe publishes new Implementation Guides for EHDS priority categories of health data. October 16, 2026. https://hl7europe.org/hl7-europe-publishes-new-implementation-guides-for-ehds-priority-categories-of-health-data/
[12] European Parliament and Council of the European Union. Regulation (EU) 2025/327 on the European Health Data Space. Official Journal of the European Union. 2025. https://eur-lex.europa.eu/eli/reg/2025/327/oj/eng
[13] U.S. Department of Health and Human Services. 45 CFR § 170.215 – Application Programming Interface Standards. Electronic Code of Federal Regulations. https://www.ecfr.gov/current/title-45/subtitle-A/subchapter-D/part-170/subpart-B/section-170.215
[14] Centers for Medicare & Medicaid Services (CMS). Fact Sheet: CMS Interoperability and Prior Authorization Final Rule (CMS-0057-F). 2024. https://www.cms.gov/files/document/fact-sheet-cms-interoperability-and-prior-authorization-final-rule-cms-0057-f.pdf
