Improving Requirements Documentation in the Medical Informatics Initiative Core Data Set Using FHIR Obligations - Lessons Learned.

INTRODUCTION

The Medical Informatics Initiative (MII) aims to enable cross-site secondary use of clinical data in Germany using a FHIR-based Core Data Set (CDS). However, current FHIR Implementation Guides (IG) often lack actor-specific guidance, leading to inconsistent interpretations and implementations.

METHODS

This technical case report explores the use of FHIR Implementation Obligations to clarify responsibilities and expected system behavior within the MII infrastructure. Obligations were modeled using the FHIR obligation extension and ActorDefinition resources, applied to the Patient profile from the CDS Person module. A prototype IG was generated using the HL7 FHIR IG publisher tooling.

RESULTS

Obligations were defined and rendered for multiple actors - such as Data Integration Centers (DIC) and the Health Research Data Portal (FDPG) - across selected Patient profile elements. Obligations were also linked to specific operations, enabling precise workflow targeting. The implementation improved the explicitness of responsibilities that were previously only implied.

DISCUSSION

The study demonstrates that obligations enhance the clarity of FHIR IGs. However, limitations remain: the MII's current IG tooling does not yet support obligations, and conformance testing was not addressed. Further work is needed to standardize ActorDefinition resources, align obligations across modules, and develop validation tooling to realize the full potential of obligation-driven specifications.