Healthcare Infrastructure & Security
Healthcare interoperability
How health systems exchange data and understand it the same way: HL7 FHIR R4 and its resources, HL7 v2 messages, CDA, code systems such as LOINC, SNOMED CT and ICD, and the national record systems of Europe.
Interoperability means two systems can exchange health data and both interpret it the same way. It takes three things: a format (HL7 FHIR R4 for APIs, HL7 v2 for most hospital messaging, CDA for documents), shared code systems (LOINC for tests, SNOMED CT for clinical terms, ICD-10 for diagnoses, ATC for medicines, UCUM for units) and agreed profiles such as the International Patient Summary, which countries use for cross-border exchange.
| API standard | HL7 FHIR R4 (4.0.1); R5 published, R4 still the most deployed |
|---|---|
| Hospital messaging | HL7 v2 (ADT, ORM, ORU) |
| Documents | CDA and C-CDA |
| Code systems | LOINC, SNOMED CT, ICD-10 / ICD-11, ATC, RxNorm, UCUM |
| Cross-border in the EU | International Patient Summary, MyHealth@EU |
What are the main health data standards?
- Healthcare interoperability standards: the complete mapOne map of the standards behind health data: HL7 v2 messages, CDA documents, FHIR resources, DICOM and DICOMweb for images, IHE profiles, openEHR for storage, OMOP for research, and the code systems they all share.
- What FHIR is and why it matters for your medical recordHL7 FHIR is the standard in which hospitals, apps and authorities exchange medical data.
- HL7 vs FHIR: the difference between HL7 v2, CDA and FHIR, and which one you needHL7 is the organisation and a family of standards; FHIR is its newest one.
- FHIR R4 vs R5: Differences and Which Version to UseFHIR R4 (2019) is the version most of the world runs on; R5 (2023) adds topic-based subscriptions and new resources, and R6 is in development.
- CDA and C-CDA explained: HL7 clinical documentsHL7 CDA is an XML standard for clinical documents that a human can read and a computer can parse.
- CDA vs FHIR: documents vs resources, explainedCDA is a document standard: one signed XML file that stays whole.
- openEHR vs FHIR: Differences and When to Use EachopenEHR and HL7 FHIR are often compared, but they solve different problems: openEHR models and stores the long-term clinical record with archetypes and templates; FHIR exchanges data between systems through resources and APIs.
- CDS Hooks explained: hooks, cards, prefetchCDS Hooks is the HL7 standard for calling a decision-support service from inside an EHR workflow: when a chart is opened, an order is selected or signed.
How are FHIR resources built?
- FHIR Patient resource explained, with an examplePatient is the FHIR resource every other clinical resource points to.
- FHIR Observation Resource Explained (with JSON Example)The Observation is the FHIR resource for measurements: lab results, vital signs, symptoms, scores.
- FHIR Condition resource explained, with an exampleCondition records a diagnosis, a problem or a symptom with its course over time.
- FHIR Encounter resource explained, with an exampleEncounter is the FHIR resource for a visit, an admission, a telehealth call or a home visit: when it happened, in what setting, who took part, why, and what was diagnosed.
- FHIR DiagnosticReport explained, with an exampleDiagnosticReport is the FHIR resource for the signed report: it groups Observations into a panel, carries the conclusion and the PDF, and records who issued it and when.
- FHIR DocumentReference vs DiagnosticReport: When to Use EachThree FHIR resources handle reports and files.
- FHIR MedicationStatement vs MedicationRequest ExplainedFHIR has four medication resources for four different facts: a prescription (MedicationRequest), a dispensing (MedicationDispense), a dose given (MedicationAdministration) and what the patient says they take (MedicationStatement).
- FHIR AllergyIntolerance Resource Explained (with Example)How an allergy is recorded in FHIR: clinicalStatus, verificationStatus, type, category, criticality and reaction with severity, coded in SNOMED CT.
- FHIR Immunization Resource Explained (Vaccination Records)How vaccinations are stored in FHIR: the Immunization resource with status, vaccine code, date, lot number and dose number, how not-given doses are recorded, and how vaccination records travel in the International Patient Summary.
- FHIR Bundle Types Explained: Transaction, Batch, Document, SearchsetA FHIR Bundle is a container for several resources.
- FHIR CodeableConcept vs Coding ExplainedNearly every coded element in FHIR is a CodeableConcept: a list of codings from different code systems plus the original text.
- FHIR profiles and extensions explainedA FHIR profile is a StructureDefinition that narrows a base resource: required elements, must-support, fixed codes, slicing, bindings, invariants.
- FHIR Implementation Guides Explained: US Core, IPS, ProfilesBase FHIR is deliberately broad; implementation guides (IGs) narrow it for a country or use case with profiles, must-support elements and terminology bindings.
- FHIR Search Parameters Explained (with Examples)How to query a FHIR server: search parameters by type (token, date, reference, string, quantity), prefixes such as ge and lt, modifiers such as :exact and :missing, chaining, _include and _revinclude, sorting, _count and paging, with example URLs for lab results.
- FHIR Subscriptions explained: topics, channels, R4 to R5A FHIR Subscription asks a server to call you when something changes.
- FHIR Bulk Data Export ($export) ExplainedThe FHIR Bulk Data Access IG defines $export to move data for many patients at once as NDJSON files.
How do hospital systems exchange messages?
- HL7 v2 ADT and ORU Messages ExplainedHL7 v2 is still how most hospital systems talk to each other.
- HL7 v2 ORM and OML order messages explainedHow an order travels in HL7 v2: the ORM^O01 general order message and the newer OML^O21 laboratory order, the ORC segment that controls the order (new, cancel, status), the OBR segment that says what was ordered, the ORR and ACK responses, and how the same order looks as a FHIR ServiceRequest.
- Interface engines explained: what they do, when you need oneAn interface engine receives messages from one system, transforms them and delivers them to others, with queues, retries, monitoring and audit.
- Hospital system integration explained: HIS, engines, lab, radiologyHow the systems inside a hospital talk to each other and to the outside: the HIS or EHR at the centre, the interface engine routing HL7 v2 and FHIR, laboratory and radiology, pharmacy, devices, telemedicine and patient apps.
- How to integrate a lab system (LIS) with an EHRA laboratory interface is the most common hospital integration and the easiest to get wrong.
Which code systems describe the data?
- What Is a LOINC Code? Lab Test Codes ExplainedLOINC gives every lab test and clinical measurement a universal code, so a result from one lab means the same in another system.
- What Is SNOMED CT? Clinical Terminology ExplainedSNOMED CT is the largest clinical terminology in the world, used to record diagnoses, findings, allergies and procedures as codes.
- LOINC vs SNOMED CT: which code goes whereLOINC names what was measured or asked: tests, panels, vital signs, document types.
- SNOMED CT vs ICD-10: what each one is forSNOMED CT is a clinical terminology for recording what a clinician sees; ICD-10 is a classification for counting diseases and billing.
- ICD-10 vs ICD-11: Differences ExplainedICD-11 replaced ICD-10 as the WHO standard in January 2022, but most countries still code in ICD-10.
- ICD-10 vs ICD-10-CM vs ICD-10-GM: national variantsThe WHO publishes ICD-10; countries publish their own modifications: ICD-10-CM in the US, ICD-10-GM in Germany, ICD-10-AM, ICD-10-CA, CIM-10 in France.
- RxNorm vs ATC Medication Codes ExplainedRxNorm names clinical drugs down to strength and form for US systems; ATC classifies active substances by organ and therapeutic group for international statistics and exchange.
- UCUM Units Explained for Lab Results (mg/dL, mmol/L, 10*3/uL)UCUM is the code system for units of measure in electronic health data.
- How to map local lab codes to LOINC, step by stepMost laboratories report with their own test codes.
- FHIR terminology servers: $lookup, $expand, $translateA terminology server holds code systems (SNOMED CT, LOINC, ICD-10), value sets and concept maps and answers questions about codes through FHIR operations.
How do national and cross-border systems work?
- National electronic health records: Europe and the US comparedA country-by-country map of national health record infrastructures: Germany's ePA, France's Mon espace santé, Italy's FSE, Spain's HCDSNS, the Dutch MedMij and LSP, the NHS in England, Austria's ELGA, Poland's P1, the Nordics and the US networks.
- MyHealth@EU and the cross-border patient summaryMyHealth@EU exchanges health data between EU countries through national contact points: the patient summary and ePrescription today, lab results, images, discharge reports and documents next.
- International Patient Summary (IPS) explainedThe IPS is the standard document a doctor who has never seen you, anywhere in the world, can read in seconds: allergies, medications, conditions, vaccinations.
- Cross-Border ePrescription in the EU (MyHealth@EU) ExplainedThrough MyHealth@EU, some EU countries let pharmacies dispense an electronic prescription issued in another member state, and share patient summaries.
- Germany's ePA: How EHR Systems Connect via the TI (FHIR)Germany's elektronische Patientenakte is hosted by health insurers, created by default since 2025 and reached through the Telematikinfrastruktur.
- France: Mon espace santé and the DMP, explainedMon espace santé is France's national personal health space, opened by default since 2022.
- Austria's ELGA electronic health record, explainedELGA is Austria's national electronic health record since 2015: opt-out and document-based, sharing discharge letters, lab and radiology reports as CDA documents through IHE XDS registries, plus e-Medikation and the central e-Impfpass.
- Italy's FSE 2.0: national health record explainedThe Fascicolo Sanitario Elettronico is Italy's health record, built by each region and connected nationally; FSE 2.0 adds a national gateway, a central data repository and FHIR.
- Spain: HCDSNS and regional health records, explainedSpain has 17 regional health services with their own records, connected through the national HCDSNS so a patient's summary and reports can be read in another region.
- Netherlands: MedMij and LSP, explainedThe Netherlands has no national health record.
- Poland: P1, IKP and e-recepta, explainedPoland rolled out e-recepta (2020), e-skierowanie (2021), e-zwolnienie, the medical events register and electronic document exchange through the central P1 platform run by the Centre for e-Health, with IKP and the mojeIKP app for citizens.
- UK: NHS Spine, GP Connect and the NHS App, explainedEngland's health data runs on the Spine (demographics, Summary Care Record, e-prescriptions, e-referrals) and FHIR APIs such as GP Connect that open GP records to other settings and the NHS App.
For developers
Anpheros Platform
Build on interoperable health data
Anpheros Platform is a FHIR R4 API for medical records, with patient consent, a free sandbox and SDKs for Dart, Flutter and TypeScript.