The objective of the message exchange module of ENHIS is to standardize the data exchange protocol and format of the health information system, the information systems of health care providers and the public health care information system.
The Electronic Health Record (EHR) exchanges all nationally approved medical documents on the message level. The individual event-based documents provided to EHR will form a person’s medical history.
All messages deployed in the EHR are standardized. The agent centre based on the infrastructure of EHR are the same and universal for all participants in the eHealth information system. The agent centre of EHR is capable of exchanging all messages that conform to the standard. The medical or other functional content of the message is handled by agents realized in ERA and other eHealth projects (functional modules). Agents can be registered with the EHR information system without modifying the digital health record infrastructure (agent centre).
Standards for the EHR message exchange are established nationally on the basis of the international XML-based standard HL7 v3. Information systems that interface with EHR (participants) must be capable of transmitting/receiving messages that comply with the EHR standards. Additional information on the international standard HL7 is available on the website http://www.hl7.org.
Also the coding of messages with medical content is standardized by using such international standards as SNOMED, LOINC, etc. Health care providers are obligated by law to comply with standards in exchanging medical data.
The Estonian eHealth Foundation deals with the standardization process of nationally approved medical document standards, classifiers and nomenclatures (including administration of web-based publication of web-based center of medical document standards and classifiers). These documents are published in the publicly available web server along with the instructions of deploying messages. The publishing centre is a central environment of publishing medical classifiers and standards that is administered and developed by the eHealth Foundation. The centre will publish the standards, classifiers and nomenclatures to be deployed in the Electronic Health Record. In addition, the centre will provide interfacing and usage instructions for the EHR information system. At present the centre is being tested which means that the data provided by it can be modified or supplemented during the implementation. The centre is available at http://pub.e-tervis.ee
Information systems that are interfaced with the EHR forward messages at the moment ceratain health event takes place, i.e. at the same moment when the information that makes up the content of the message is created and stored in the information system of the health care provider. The message exchange channel is secure public (Data Exchange Layer X-Road).