Healthcare Interoperability Explained: FHIR, HL7 and What Actually Matters
A practical explanation of health data exchange standards: what each one does, where they're used, and which ones your practice actually needs to care about.
Healthcare SBC Integration Team
Interoperability Engineering ·
Interoperability discussions collapse quickly into acronyms. This is a practical guide to what each standard actually does and when it matters to a practice.
HL7 version 2: the workhorse
HL7v2 is a messaging standard from the late 1980s that still carries the overwhelming majority of clinical data exchange in production today. It's pipe-delimited, cryptic, and enormously effective at moving discrete events between systems.
The message types you'll encounter most: ADT for admissions, discharges and transfers; ORM for orders; ORU for results; SIU for scheduling; and DFT for charges. If your practice receives lab results electronically, you're almost certainly receiving ORU messages.
FHIR: the modern API standard
FHIR (Fast Healthcare Interoperability Resources) is a REST API standard using JSON, built around discrete resources like Patient, Observation, Condition and MedicationRequest.
FHIR is what powers patient-access APIs, third-party health apps and SMART on FHIR applications launched from inside an EHR. It's also the standard federal regulation increasingly points to, which is why it matters even if you never touch it directly.
CCDA: the document approach
Where HL7v2 sends events and FHIR sends discrete resources, CCDA sends documents: a structured XML summary of a patient's care, used for transitions of care, referrals and patient record requests.
CCDA generation and consumption is required for ONC certification and is what most HIE query-and-retrieve exchange returns today.
X12 EDI: the money side
Everything above concerns clinical data. Financial exchange runs on X12 EDI: 270/271 for eligibility, 276/277 for claim status, 837 for claims, 835 for remittance and 278 for authorizations.
This is the least discussed and most financially consequential category of interoperability in a practice. Real-time eligibility alone prevents a large share of denials.
What actually matters for your practice
- Lab and imaging result interfaces (HL7v2 ORU): eliminates faxes and manual entry
- Hospital ADT feeds: enables transitional care management and post-discharge follow-up
- Real-time eligibility (270/271): prevents the largest single category of denials
- Electronic remittance (835): enables automated payment posting
- Patient-access FHIR API: required for information-blocking compliance
- HIE connectivity: gives providers outside records at the point of care
The regulatory floor
The 21st Century Cures Act information-blocking provisions require that practices not unreasonably interfere with the access, exchange or use of electronic health information. In practice this means patients and other providers must be able to get records without artificial friction.
This isn't optional, and 'our vendor charges for that interface' is generally not an accepted justification. Building standards-based exchange is now a compliance requirement, not a differentiator.