Health Level 7

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 as a name for the organization that develops standards in health care and support, as well as for versions 2.x and version 3 of the standards and other standards that are developed by the local HL7 organizations in over 35 countries.

The number 7 of the name HL7 refers to the layer 7 of the ISO / OSI reference model for communication ( ISO7498 -1) and is expressing that here the communication is described on the application level.

• 2.1 Technical Objectives of HL7
• 2.2 Principle of operation

• 3.1 HL7 version 2.x 3.1.1 HL7 version 2 message types
• 3.1.2 segments
• 3.1.3 Application Example

Origin

HL7 was founded in 1987 in the U.S., an industry standard (English: Standard) to write for clinical information systems. HL7, Inc. is an American norm group that is accredited by the American National Standards Institute, the American National Standards Institute (ANSI) in 1994. The focus of HL7 in the U.S. is in the data processing of medical data and administrative data.

HL7 affiliated organizations, known as affiliates, now exist in over 30 countries. The first partner company was founded in Germany in 1993. In the U.S., HL7 is an accredited only by many groups addressing industry standards in health care.

Spread

Meanwhile HL7 works as a standards body or international level as associated organization with ISO, CEN, IHTSDO and the CDISC in the Joint Initiative Council of ISO TC 215. In Germany, which is a mirror of this initiative, the competence network together to eHealth standards.

Cooperations exist with various other groups, such as Integrating the Healthcare Enterprise is an initiative of European users and manufacturers with the aim to standardize the exchange of information between IT systems in healthcare and harmonize.

HL7 in Germany

The German organization of HL7 is a registered charity since 1993.

Voluntary membership in the national HL7 organization is based on personal involvement of clinical users and especially to industrial interest (about 100 members). Of the approximately 1,000 hospitals in Germany are about 50 member HL7 Germany. Organisations of bodies of self-government, operating organizations (eg gematik ) and federal agencies (eg DIMDI ) are among the members.

In Germany HL7 is practically only used within hospitals and hardly ever for the exchange of data between the clinical and the established sector in health care. This is partly because that has developed a wealth of data exchange formats in private practice in the practice software, the xDT are probably the formats with the largest circulation.

HL7 and standardization in NAMed

HL7 is working in Germany as an informal group cooperatively with the bodies of the national standards. In the standardization member companies work of HL7 Standards Committee eV NAMed of DIN with. HL7 itself is not member of the DIN. The first proposed standard was submitted to HL7 for the DIN 2008 as the acquisition of ISO 10781 (DIN EN ISO DIS 10781, Publication date: 2008-05, draft).

Effect of HL7

Due to the federal structure of the German administration in healthcare, standardization remains with reference to HL7 far behind the possibilities of the economy. In addition, it is never objective of the industry to provide a standards organization a mandate for restricting competition unification.

Therefore, the apparent power is low to the current discussion, for example, to the electronic patient record (see DIN EN ISO 10781, draft) and no contribution to the discussion of the balance between data availability and data security. An effect on the productivity of hospital information systems (HIS = hospital information systems ) eV is due to the activities of HL7 not reported, the variability in the supply of KIS is not yet influenced by the standardization according to HL7.

Public funding for a broader use of HL7 does not exist at the federal level or in -country programs. A different situation exists in the Netherlands: There is a national program to launch implementation of HL7 standards in national use. These activities are supported by a German company as a contract performance from the Netherlands.

Technical objectives of HL7

Goal of HL7 standards is to simplify the implementation of the medical processes between the systems involved and the creation of interoperability between different operators and manufacturers.

Operation

HL7 creates international standards for the exchange between systems and between institutions, the markup of clinical documents (eg Clinical Document Architecture). A common misconception about HL7 is that this is a software product. In fact, it denotes specifications. The best known are the 2.x versions of HL7 message format, which today are used mainly in hospitals.

HL7 is divided into working groups ( ' Workgroups ') that work cooperatively on the standard. The working groups are directly responsible for the content of the standards. A list of the task fields and the current organizations can be found on the official website hl7.org.

Intended use of the HL7 standards

The HL7 standards can be implemented free of charge; so there are no licenses or fees for the development or for the runtime environment. The distribution of the current standards, although paid, but earlier versions of HL7 2.x standards can be downloaded for free.

HL7 provides interoperability between different information systems in healthcare (eg, hospital information systems (HIS), practice management systems ( PVS), laboratory information management systems (LIMS ), radiology information systems ( RIS) ), systems for providing billing and between systems that act as electronic patient record.

HL7 version 2.x

The series of HL7 Version 2 standard is widely used and system integration within hospitals, for example, for communication of patient and performance data and performance requirements and findings. It will be covered in the hospital the necessary application: Patient Data Administration, communicating findings, performance requirement and transmission, document and exchange of master data, employee data, logistics, materials 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 can be ( as MLLP ) and find parser for HL7 messages, the processing of messages, segments and fields, however, is application- specific and must be implemented by the application developer.

HL7 version 2 message types

The following message types are used ( Auszug! )

• ADT: patient master data and residence data ( Admission, Discharge, Transfer)
• ORM: Requesting a study (Order Message)
• ORR: Response to an ORM message ( OrderResponse )
• ORU: Transmission of Results (Observation Result Unsolicited )
• MDM: transfer of medical documents ( Medical Document Management)
• DFT: submission of performance data for billing ( Detailed Financial Transactions )
• BAR: Transfer of performance in accordance with the OPS standard ( Billing Account Record)

The messages are divided into segments and fields. The following segments are available ( Auszug! )

Segments

HL7 defined include the following segment types:

• EVN: Message ( Event Type)
• MSH: header (message header)
• OBR ( Observation Request)
• OBX ( Observation Result)
• ORC ( Common Order)
• PID ( Patient Identification)
• PV1 ( Patient Visit )
• SFT ( Software Segment)

Example of use

Through an event (Event) the sending of a message is triggered. One such event is, for example, the hospitalization of a patient. After recording on the KIS has been entered, the HIS generates a message of type ADT ( Admission, Transfer, Discharge, ie " admission, transfer, dismissal " ) and the event type eg A01, A02, A03, etc.

About this message is notified its associated clinical subsystems, so that the patient with its master data is there already known. HL7 messages consist of ' segments ', which are divided into ' fields' that are filled with certain ' data types '.

The following example ( see illustrations) a HL7 message type ADT and the 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 each HL7 message. It contains information about the used field separator, the communicating applications, the message and event type and the used HL7 version. The control number (Message Control ID ) in section 10 is clearly on the specification and in the confirmation message of the subsystem, called the acknowledgment referenced.

The PID segment contains all the master data of the patient (name, birthday, address, health insurance number, etc.).

The PV1 segment contains data for one case. These include, inter alia, the recording mode, the settlement, the assigned location of the patient ( station, rooms, bed) and the referring physician.

HL7 Version 3

In the previous version 2 of HL7 is a pragmatic approach, the message exchange in the foreground. This allows the development of faster solutions for pending communication needs - one of the original goals of HL7 - but also carries the risk of the development of inconsistencies.

HL7 version 3 is tailored to the communication needs of the entire health care. The development of this new " generation HL7 " began in 1995, a first standard publication was in 2005. V3 is based, as opposed 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 gain a common understanding about objects and processes between all communication partners. This requires, inter alia, arrangements for form and content, but also on the meaning (semantics), to be used terminologies and the underlying processes are taken.

It is the complete life cycle of a standards - development, adaptation, recognition of the market, use and compliance with Standards - unified and automated. The defined to HL7 Development Framework (HDF ) is based on a series of models which follow the ISO standard, the Unified Modeling Language ( UML). For the models with the necessary information can be derived directly and are therefore requirements of modern IT systems, such as support for development of software.

The HL7 V3 development methodology is ahead of previous ways of developing a news important steps. However, the benefit of a sophisticated methodology also brings with it the need to understand a more comprehensive set of terms and procedures. In addition to the normative part therefore informative parts are received in the HL7 standard. In addition, official, however, nonstandard materials are provided.

The Clinical Document Architecture (CDA, ISO 27932 ) describes an XML-based format for sharing documents in health care, for example, a discharge letters for a patient from the hospital to the family physician.

Arden syntax

Arden syntax describes how knowledge of the processes can be saved in health care and how this can be used to support structured medical decisions (decision support ).

Fhir

This next generation of the HL7 standard is still in development. Fhir as an exchange format is also XML or JSON - based and easier to implement than HL7 V3. Fhir is currently known as a draft standard for trial use, in which the application ability is checked.