Status of the first nationwide dissemination of FHIR-based standards in Denmark. The Danish health data sharing ecosystem was established 30+ years ago, and now is the time for transition. The Danish modernization strategy consists of FHIR based sharing formats and choice of data sharing paradigm: messaging, document sharing and RESTful services. The strategy is to use all data sharing paradigms offered by FHIR, depending the use case.

The first case is the HospitalNotification standard, sent from regional hospitals to the municipality care team. This, our first FHIR message-type is now implemented nationwide, and we present lessons learned as an early adaptor of FHIR messaging. The message is revised and enhanced from an old Danish EDIFACT message-type.

Lessons learned are gains from using HL7 state machine and the intentions of HL7v2 ADT-messages, where notification is expanded from admission and discharge to also support for status as ex. hospital leave, and a transition with fewer admissions and more hospital encounters up to 72 hours, and increased use of telemedicine. The requirement for notifications now also support multiple recipients, since there are multiple EHR’s in the municipality.

Other cases of data sharing paradigms are under development or implementation, ex. IHE XDS document sharing of the patients "diagnosis card" (a problem list), with the great benefit of using the same FHIR building blocks cross multiple sharing paradigms. Another ex. is an only-once FHIR-service based platform where the municipalities can upload data for multiple purpose like statistics and quality work.

Lessons learned are also unexpected costs, and we present our analysis for reasons as due to new functionality, new FHIR technology, or FHIR messaging.

The presentation gives lessons learned from the FHIR implementation projects, and brings value to the broader evaluation of FHIR implementations and gives recommendations for new projects.