Bridging the Gap between HL7 CDA and HL7 FHIR: A JSON Based Mapping

The Austrian electronic health record (EHR) system ELGA went live in December 2016. It is a document oriented EHR system and is based on the HL7 Clinical Document Architecture (CDA). The HL7 Fast Healthcare Interoperability Resources (FHIR) is a relatively new standard that combines the advantages of HL7 messages and CDA Documents. In order to offer easier access to information stored in ELGA we present a method based on adapted FHIR resources to map CDA documents to FHIR resources. A proof-of-concept tool using Java, the open-source FHIR framework HAPI-FHIR and publicly available FHIR servers was created to evaluate the presented mapping. In contrast to other approaches the close resemblance of the mapping file to the FHIR specification allows existing FHIR infrastructure to be reused. In order to reduce information overload and facilitate the access to CDA documents, FHIR could offer a standardized way to query CDA data on a fine granular base in Austria.