Interfaces & APIs for healthcare: The key to digital interoperability

The Core Problem in Healthcare IT

Short: Healthcare institutions run on dozens of separate systems.

Healthcare institutions run on dozens of separate systems. Hospital information systems, electronic health records, laboratory platforms, imaging systems, and billing infrastructure rarely communicate natively.

The result: data must be transferred manually or through fragile point-to-point connections. Clinical staff waste time on administrative data entry. Errors occur at every handoff.

APIs solve this by creating standardized data exchange between systems — regardless of which vendor built each one.

Two Approaches to Healthcare Data Exchange

Traditional: HL7 v2.x and DICOM

The Health Level Seven (HL7) specification — especially version 2.x — has been used for decades. It defines message structures for clinical and operational data: patient registration, lab results, appointment scheduling.

DICOM governs medical image exchange. Radiographs and CT scans use this standard to move between imaging systems and viewing stations.

Both standards are widely deployed. Both are also rigid. They lack support for modern web and mobile environments.

Modern: FHIR

FHIR (Fast Healthcare Interoperability Resources), developed by HL7 International, uses REST architecture and standard data formats (JSON, XML). It was designed for web and mobile from the start.

FHIR makes it possible to build consumer-facing health apps, patient portals, and cross-institution data sharing using the same tools as any modern web service.

Comparison: HL7 v2.x vs. FHIR

Dimension	HL7 v2.x	FHIR
Technology foundation	Proprietary protocols, message-based	RESTful services, HTTP
Data structure	Segment-based, complex to parse	JSON, XML — straightforward
Integration capability	Point-to-point, fragmented	Standardized, modular
Application scope	Institution-to-institution	Web, mobile, cloud platforms
Implementation timeline	Long, resource-intensive	Faster, developer-friendly

Practical API Use Cases in Healthcare

Cross-Institution Patient Data Sharing

FHIR APIs allow hospitals, GP practices, and specialist clinics to share patient records securely. With patient consent, a specialist receives relevant history before the appointment — without fax or CD.

Remote Patient Monitoring

Wearable devices transmit vital signs via API to clinical monitoring systems. Alerts trigger when parameters fall outside defined thresholds. Clinicians receive relevant notifications — not raw data streams.

AI-Assisted Diagnostics

AI diagnostic systems receive medical images or lab values through standardized APIs. Results return to the clinical workflow system automatically. The clinician sees AI-generated findings alongside standard reports.

Digital Appointment and Referral Management

Booking APIs connect patient portals to clinical scheduling systems. Referral APIs route specialist requests with relevant patient data attached. Manual phone-based coordination decreases.

What Healthcare Organizations Must Address in API Projects

Data Protection Under GDPR and KHZG

Health data falls under GDPR Article 9 — the strictest protection category. Any API that processes patient data requires:

• A legal basis for processing (typically explicit consent or medical necessity)
• Data processing agreements with all involved parties
• Technical and organizational measures (TOMs) documented and audited

The Hospital Future Act (KHZG) in Germany funds digital infrastructure for hospitals — including interoperability projects. FHIR-based integrations are explicitly supported.

Access Control and Auditability

Every API call that touches patient data must be logged. Access must be role-based. Audit logs must be tamper-proof and retained for legally required periods.

"A well-designed API is the invisible bridge between systems — and often the biggest lever for efficiency." — Björn Groenewold, Managing Director, Groenewold IT Solutions