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Introduction: Structured, interoperable medication data is essential for safe prescribing, clinical decision support (CDSS), and cross-institutional pharmacoepidemiological research. In Germany, several FHIR^®-based Implementation Guides (IGs) exist for medication representation, including profiles developed by KBV (eRezept), Gematik (ePA), MII, MIO, ISiK, and the European EU-MPD. However, it remains unclear whether these profiles support machine-readable representation of complex dosage instructions, particularly those with conditional logic tied to laboratory results. Addressing this is critical for automating clinical workflows and ensuring research-ready data quality.

Methods: We constructed a test scenario using a conditional, multi-phase Phenprocoumon regimen: “3 mg daily for 3 days, then continue with 3 mg if INR <2, or reduce to 1.5 mg if INR ≥2.” This scenario was encoded using FHIR^® R5 resources (e.g., MedicationRequest, Dosage, Observation, PlanDefinition). Six current German/European medication IGs were reviewed for their ability to support this scenario along eight evaluation axes: identifier coding, simple dosage, multi-phase dosage, conditional dosage, PRN, lab linkage, therapy goals, and decision logic artifacts. We rated each axis using a traffic-light system (green/yellow/red) and mapped them to HIMSS interoperability levels (foundational, structural, semantic, organizational).

Results: All profiles support encoding of basic dosages (quantity, frequency). Four of the six (ePA, MIO, ISiK, EU-MPD) support multiple dosage phases. However, none of the profiles allows conditional logic (e.g., IF INR <2 THEN 3 mg ELSE 1.5 mg) to be represented in a computable format. Such rules must be expressed in narrative fields (e.g., patientInstruction). Structured linkage to laboratory data (e.g., INR values) and formal therapy goals are either unsupported or weakly defined. Key FHIR^® resources for computable workflows (e.g., PlanDefinition, RequestGroup) are absent or excluded from these IGs. Only the EU-MPD mandates the use of international terminologies like ATC and UCUM, while most German profiles lack semantic enforcement.

Conclusion: German FHIR^® medication profiles enable foundational and structural interoperability but fall short at the semantic and organizational levels. As a result, they cannot support automated decision-making or research use cases involving complex dosing. This limits both the safety and secondary usability of medication data.

We propose a coordinated roadmap to close this gap:

• Interoperability Maturity Model: Classify and guide profiles from L0 (narrative) to L3 (computable).
• Standardized Conditional Logic: Develop a canonical Dosage.condition extension.
• Executable Examples: Include runnable FHIR® Bundles in implementation guides and clinical guidelines.
• CDSS Integration: Align profiles with CDS Hooks and BPM+ for automated support.

These steps require alignment across German and European stakeholders (e.g., Gematik, HL7 Germany, KBV, MII) and should be prioritized to achieve research-capable, patient-safe digital prescribing infrastructures.

The authors declare that they have no competing interests.

The authors declare that an ethics committee vote is not required.

References

[1] Sass J, Zabka S, Essenwanger A, et al. Fast Healthcare Interoperability Resources (FHIR) representation of medication data derived from German procedure codes using IDMP terminology. Stud Health Technol Inform. 2021;281:231-235.
[2] Salgado-Baez E, Heidepriem R, Delucchi Danhier R, et al. Toward interoperable digital medication records on FHIR: development and technical validation of a minimal core dataset. JMIR Med Inform. 2025;13(1):e64099.
[3] Jung S, Bae S, Seong D, et al. Shared interoperable clinical decision support service for drug-allergy interaction checks: implementation study. JMIR Med Inform. 2022;10(11):e40338.
[4] Tabari P, Costagliola G, De Rosa M, Boeker M. State-of-the-art FHIR-based data model and structure implementations: systematic scoping review. JMIR Med Inform. 2024;12:e58445.
[5] HL7 International. FHIR US Core Implementation Guide (v8.0.0) – MedicationRequest Profile Guidance. 2023.