HL7 and FHIR, explained for clinics

Why standards matter to a clinic

Every system in a clinic stores information in its own way. A standard is an agreement on the shape of that information when it moves: what a lab result looks like, what an appointment contains, how a patient is identified. The more of a clinic's systems speak the same standard, the less custom work each connection needs.

HL7 version 2: the workhorse

HL7 v2 dates from the late 1980s and still carries most of the clinical messages exchanged in North America. A message is a block of text made of segments, each a line of fields separated by vertical bars. It is compact and reliable, and every hospital and lab system speaks it.

The limits of HL7 v2 are its age: messages are pushed from one system to another in shapes fixed decades ago, every interface needs its local variations agreed, and there is no standard way to ask a system a question.

FHIR: health information for the web

FHIR (Fast Healthcare Interoperability Resources, pronounced "fire") reorganizes health information into resources: small, defined building blocks that can be read, created, updated and searched over a standard web API. R4 is the release most national specifications build on.

FHIR in Canada

Canada Health Infoway publishes the pan-Canadian interoperability specifications, built on FHIR R4. The ones a clinic is most likely to hear about are:

• CA Core+, the Canadian baseline profiles for common clinical data.
• PS-CA, the Pan-Canadian Patient Summary: a standard summary of a patient's key health information.
• CA:FeX, the FHIR exchange specification for moving information between systems.
• CA:eReC, the eReferral and eConsult specification.

Clinical terminology standards sit underneath: SNOMED CT Canadian Edition for clinical concepts, and pCLOCD and LOINC for laboratory observations. Federal legislation now before Parliament, Bill S-5, would give interoperability requirements legal force for health IT vendors.

FHIR in the United States

Under the 21st Century Cures Act, certified health IT must provide standardized FHIR APIs for patient and population access, and information blocking is prohibited. US clinics on certified EHRs therefore have a FHIR route into at least part of their record.

What this means when you connect your clinic

Standards make integration cheaper. Making it automatic still takes work: clinic EMRs support FHIR unevenly, provincial feeds still run on HL7 v2, and most vendors extend the standards with their own APIs for the records the standards do not yet cover. A working integration uses each route where it is strongest and applies the clinic's own rules on top. That combination is what our EMR integration guide calls the layer in the middle.

Questions, answered