HL7
Health Level 7 ( HL7 ) is a group of international standards for the exchange of data between healthcare organizations and their computer systems .
HL7 is used to refer to the organization that develops and supports health care standards, and versions 2.x and 3 of the standards and other standards developed by local HL7 organizations in over 35 countries.
The number 7 of the name HL7 refers to layer 7 of the ISO / OSI reference model for communication (ISO7498-1) and expresses that the communication is described here at the application level.
origin
HL7 was founded in the USA in 1987 to write an industry standard for clinical information systems. HL7, Inc. is an American standards group that has been accredited by the American National Standards Institute (ANSI) since 1994. The main focus of HL7 in the USA is data processing for medical data and administrative data.
HL7 affiliated organizations, so-called affiliates, now exist in over 30 countries. The first partner company was founded in Germany in 1993. In the USA too, HL7 is just one of many accredited groups working on industry standards in healthcare.
Spread
In the meantime, HL7 works as a standards body on an international level as an associated organization with ISO , CEN , IHTSDO and CDISC in the Joint Initiative Council of ISO TC 215. In Germany, as a mirror of this initiative, the competence network has merged to form eHealth standards.
There are also collaborations with various other groups, such as IHE as an initiative of users and manufacturers with the aim of standardizing and harmonizing the exchange of information between IT systems in the healthcare sector.
HL7 in Germany
The German organization of HL7 has been a registered association since 1993.
The voluntary membership in the national HL7 organization is based on the personal commitment of clinical users and above all on industrial interest (approx. 100 members). Of the approx. 1000 clinics in Germany, around 50 are members of HL7 Germany. Organizations of corporate bodies, self-administration, business organizations (e.g. gematik) and federal authorities (e.g. DIMDI) are also members.
In Germany, HL7 is practically only used within hospitals and almost never for the exchange of data between the clinical and the private sector in the healthcare sector. This is partly due to the fact that an abundance of data exchange formats has developed in practice software in the private practice area, with the xDT being arguably the most widely used formats.
HL7 and standardization in NAMed
HL7 works in Germany as an informal group cooperative with the committees of the national standardization. Member companies of HL7 e. V. in the DIN standards committee NAMed . HL7 itself is not a member of DIN. The first standard proposal for HL7 was presented at DIN 2008 as an adoption of ISO standard 10781 (DIN EN ISO DIS 10781, edition 2008-05, draft).
Effect of HL7
As a result of the federal structure of the German administration, also in the health care system, the standardization remains far behind the possibilities of the national economy, also with reference to HL7. In addition, the industry is unwilling to give a standards organization a mandate for a standardization that restricts competition.
Therefore, the discernible performance for the current discussion is low, for example for the electronic patient record and no contribution to the discussion of the balance between data availability and data security. An effect on the productivity of clinical information systems (HIS = hospital information systems) through the activities of HL7 eV is not reported, the variability of the supply of HIS has so far not been influenced by the standardization according to HL7.
There is no public funding for a wider use of HL7, neither at federal level nor in state programs. The situation is different in the Netherlands, where there is a national program for the implementation of the HL7 standards in national use. These activities are supported by a German company as a contract service from the Netherlands.
Technical objective of HL7
The aim of HL7 standards is to simplify the implementation of medical processes between the systems involved and to create interoperability between different operators and manufacturers.
Working method
HL7 creates international standards for the exchange between systems and between institutions, for the markup of clinical documents (e.g. the Clinical Document Architecture ). A common misconception about HL7 is that it is a software product. In fact, it denotes specifications. The best known are the 2.x versions of the HL7 message format, which are mainly used in hospitals today.
HL7 is divided into work groups which work cooperatively on the standard. The working groups are directly responsible for the content of the standards. A list with the fields of activity and the current organizations can be found on the official website.
Purpose of the HL7 standards
The HL7 standards can be implemented free of charge, so there are no licenses or fees for development or for the runtime environment. The distribution of the current standards is chargeable.
HL7 offers interoperability between various information systems in the healthcare sector (e.g. hospital information systems (HIS), practice management systems (PVS), laboratory information management systems (LIMS), radiology information systems (RIS)), systems for service accounting and between systems that function as electronic patient files.
HL7 version 2.x
The series of HL7 Version 2 standards is widely used and is used for system integration within hospitals, for example for communicating patient and performance data as well as performance requirements and findings. The necessary areas of application in the hospital are covered: patient data administration, communication of findings, service request and transfer, document and master data exchange, employee data as well as logistics, material management and resource planning.
The exchange format for HL7 Version 2 is simple and text-based. HL7 is not plug and play . Although HL7 transport layers (such as MLLP) and parsers for HL7 messages can be found, the processing of messages, segments and fields is application-specific and must be implemented by the application developer.
HL7 version 2 message types
The following message types are used (excerpt!)
- ADT: patient master data and common data ( A dmission, D ischarge, T ransfer)
- ORM: Request for an investigation ( Or der M essage)
- ORR: Reply to an ORM message ( Or der R esponse, status messages)
- ORU: Degree of transmission ( O bservation R esult U nsolicited)
- MDM: Transmission of medical documents ( M edical D ocument M anagement)
- DFT: transmission power data for billing ( D etailed F inancial T ransactions)
- BAR: Transmission of performance data according to the OPS standard and the ICD10 standard ( B illing A ccount R ecord)
The messages are divided into segments and fields. The following segments exist (excerpt!)
Segments
HL7 defines the following segment types, among others:
- EVN: Message type ( Ev e n t Type)
- MSA: Acknowledgment ( M e s sage A cknowledgment)
- MSH: header ( M e s say H eader)
- OBR: ( Ob servation R equest)
- OBX: ( Ob servation Result)
- ORC: ( C ommon Or der)
- PID ( P atient Id entification)
- PV1: ( P atient V isit)
- SFT: ( S o f tware Segmen t )
- ERR: Error ( Err or)
Application example
The dispatch of a message is triggered by an event. Such an event is, for example, the hospitalization of a patient. After the admission has been entered on the HIS , the HIS generates a message of the type ADT ( Admission, Transfer, Discharge , ie "Admission, transfer, discharge") and the event type e.g. B. A01, A02, A03 etc.
This message is used to inform the connected clinical subsystems so that the patient and their master data are already known there. HL7 messages consist of 'segments' which are divided into 'fields' which are filled with certain 'data types'.
The following example (see figures) of an HL7 message of type ADT and event type A01 (new recording) consists of three segments: Message Header (MSH) , Patient Identification (PID) and Patient Visit (PV1) .
The MSH segment is at the beginning of every HL7 message. It contains information on the field separators used, the communicating applications, the message and event type and the HL7 version used. The control number ( Message Control ID ) in field 10 is unique according to the specification and is referenced in the confirmation message of the subsystem, the so-called acknowledgment .
The PID segment contains all of the patient's master data (name, birthday, address, health insurance number, etc.).
The PV1 segment contains data on a case. These include a. the type of admission, the type of billing, the assigned location of the patient (ward, room, bed) and the referring doctor.
HL7 version 3
In the previous version 2 of HL7, a pragmatic approach to message exchange is in the foreground. This allows the development of quick solutions for upcoming communication needs - one of the original goals of HL7 - but also carries the risk of developing inconsistencies.
HL7 Version 3 is tailored to the communication needs of the entire healthcare sector. The development of this new "Generation HL7" began in 1995, the first standard publication followed in 2005. V3 is based, in contrast to version 2, on a formal methodology (HL7 Development Framework HDF) and object-oriented principles.
One of the main goals of HL7 V3 is to achieve a uniform understanding of objects and processes between all communication partners. For this purpose, agreements are made about form and content, but also about meaning (semantics), the terminology to be used and the underlying processes.
The complete lifecycle of a standard - development, adaptation, market acceptance, use and compliance with the standard - is standardized and automated. The HL7 Development Framework (HDF) defined for this is based on a series of models that follow the ISO standard of the Unified Modeling Language (UML). The necessary messages are derived directly from the models and should therefore also meet the requirements of modern IT systems, e.g. B. in software development.
The HL7 V3 development methodology is significantly ahead of previous ways of developing messages. However, the usefulness of a more sophisticated methodology also brings with it the need to understand a wider range of terms and procedures. In addition to the normative parts, informative parts are therefore also included in the HL7 standard. In addition, official but non-standard materials are provided.
The Clinical Document Architecture (CDA, ISO 27932) describes an XML -based format for the exchange of documents in the healthcare system, for example a discharge letter for a patient from the hospital to the general practitioner.
Arden syntax
The Arden syntax describes how knowledge about processes in healthcare can be stored and how this can be used to support medical decisions in a structured manner (decision support).
FHIR
Fast Healthcare Interoperability Resources (FHIR) is the next generation of HL7 standards. It is an exchange format that is also based on XML or JSON and is easier to implement than HL7 V3. The current version is FHIR Release # 4 from December 27, 2018: First Normative Content .
literature
- Gunther Schadow: Hospital communication with HL7 - analysis, implementation and application of a protocol standard for medical data communication . Shaker 2000, ISBN 3-8265-7887-2 .
- Barry Smith and Werner Ceusters: HL7 RIM: An Incoherent Standard (PDF; 217 kB) (MIE 2006), Studies in Health Technology and Informatics, vol. 124, 133-138.
Web links
- German website for Health Level Seven
- Austrian website on Health Level Seven
- HL7 user group Switzerland
- HL7 is a member of the Joint Initiative on SDO Global Health Informatics Standardization
Individual evidence
- ^ Joint Initiative on SDO Global Health Informatics Standardization
- ↑ HL7 Agreements
- ^ Structure of HL7 Germany
- ↑ DIN NAMed annual report 2007 (PDF; 2.4 MB)
- ↑ DIN: DIN EN ISO 10781 Medical Informatics - HL 7 Functional Model for an Electronic Health Record System (EHRS FM), Edition 2 (ISO 10781: 2015); English version EN ISO 10781: 2015 . Ed .: DIN. Berlin December 2015, p. 81 .
- ^ Working groups HL7 International
- ↑ All Published Versions of FHIR. HL7 International, accessed February 17, 2018 .