Aug 2019
HL7-Health Standards
(Last Updated On: October 3, 2019)

This post was updated to reflect current trends and information.

HL7 – Health information exchange

Digital transformation has affected many industries and processes. One of the processes affected is Health Information Exchange — HIE. It is evident, that effective exchange of medical data between various health institutions allows serving more people and could reduce the cost of treatment.

In this article, we will discuss the international standards for the transfer of clinical and administrative data Health Level 7 (HL7).

Health Information System (HIS)

Introduction to HL7 StandardsHealth service digitization has led to the creation of many Health Information System (HIS) which are systems to automate document management in a medical institution and consists of electronic medical records, data from various studies, monitoring from different medical devices related to the patient’s condition, and other information.

The focus of any Health Information System is the Electronic Health Records (EHR). The medical information stored in the EHR is represented by a complex set of heterogeneous data, both textual, digital, and graphics, which are originally located in different systems. For successful synchronization of this information in different HIS, it is necessary not only to transfer them via protocols, but also to convert this data to the form that is accepted in another Health Information System, and vice versa.

To solve Health Information Systems integration challenges, there is a set of international standards that define the rules for the exchange of information in the Healthcare Industry.

Health Information Exchange standards

It should be mentioned that over the past 50 years, many different standards for Health Information Exchange have been developed. The most Popular are:

However, by comparison all other, HL7 standard showed the best results and is currently the most common in the Healthcare Industry.

How is HL7 used in healthcare

The following is a comparative table of the functionality of the three standards:

 Hospital information system  X  X  X
 Radiology information  X  –  X
 Storage and sharing of images  X  –  X
 Master Patient Index (MPI)  –  –  X
 Graphic diagnosis  X  –  X
 Archiving  X  –  X
 Comments on the diagnosis  –  –  X
 Images in the documentation  X  –  X
 Intermediate reports  –  –  X
 Video in the documentation  –  –  X
 Patient registration  –  –  X
 Electronic health record (EHR)  X  X  X
 Invoice creation  –  X  X
 Recipes  –  –  X
 Transforming data  –  –  X
 Emergency information  –  –  X
 Medical practices  –  X  X


As you can see in the table above, HL7 Standard can transmit graphic images. This option was developed due to the specifics of the healthcare industry, since often during the examination and treatment of patients in addition to text, visual information is generated. This may include x-rays, ultrasound, and tomographic results, and the volume of visual graphics data is growing annually.

What is HL7 standard?

HL7 - Health information exchangeThe HL7 standard (Health Level 7) is the set of international standards for the exchange, management, and integration of electronic medical information.

Health Level Seven International (HL7) is not-for profit organizations that are developing standards for the integration, exchange, sharing, and retrieval of electronic health information. HL7 has more than 1,600 members from 50 countries, including over 500 corporate members such as healthcare providers, government agencies, pharmaceutical companies, and others.

The HL7 standard is widely used for electronic document exchange in medical institutions, especially in those where the patient receives intensive care, for example, in hospitals.

HL7 includes:

Objectives, concepts and general structure of HL7

In the HL7  “Seventh level” – an analogy with the highest level of the communication model of Open Systems Interconnection model (OSI). The seventh level supports the performance of such tasks as:

  • structuring the transmitted data;
  • system design capabilities;
  • achieving gear consistency;
  • security;
  • identification of participants;
  • availability

The most important components of HL7

RIM Reference Information Model

Reference Information Model – the basic concept for all HL7 is the information model – the main source of data content for all HL7 messages and documents.

RIM consists of several technologies:

  • USAM – Unified Service Action Model. An object model for any action possible in the system;
  • MIM – Message Information Model. Messages models;
  • R-MIM Refined Message Information Model. A context-based model.


Functional model in terms of system design UML. The concept of a storyboard is taken from the movie industry and represent significant moments of message transmission as frames. Each frame describes the key participants and their interaction. A set of frames represents both the transmission of a message and the functioning of a large system.

A description of the operation of triggers that launching events (for example, a form after filling out becomes “filled” and / or “signed”). Each interaction is described by a storyboard (in the UML sequence diagram).

Each interaction is described by a storyboard (in the UML sequence diagram). By means of RIM and storyboard, it is possible to express a highly personalized patient history.


Descriptions of the specifics of subject areas. An attribute in a RIM-description can be a dictionary item.


Hierarchical Message Descriptor – determinant of the hierarchical structure of the message.

HMD principles:

  • The transmission system must understand the genesis of classes.
  • messages during transmission are arranged in a linear structured sequence.

EHR System

Electronic Health Record Systems – the system of electronic medical history. Description of the full functionality of the EHR consisting of sections:

  • Care Management
  • Clinical Support
  • Information Infrastructure – a total of 125 functions.

HL7 FHIR (Fast Healthcare Interoperability Resources)

HL7 FHIR (Fast Healthcare Interoperability Resources) The most popular version of HL7 standards is HL7 FHIR (Health Level 7 – Fast Healthcare Interoperability Resources). According to HL7 International Annual report 2018 one of the strategic goals of this organization is: “Establish Fast Healthcare Interoperability Resources (FHIR) as a primary standard for global health data interoperability and enhance and maintain quality of and accessibility to HL7 standards in current use”.


What is the difference between hl7 and FHIR?

HL7 FHIR combines all the successful solutions of previous versions of HL7 and contains a new architectural concept, as well as an open approach to the development and evolution of the standard.

Key principles of HL7 FHIR

  • focus on practical implementation (convenient for developers)
  • Following the evolving web technologies
  • Incorporating only the most important/common concepts into the specification to keep it small and describe 20% of the concepts involved in 80% of the informatized scenarios;
  • Open standard and Open Source development
  • Mandatory “human-readable data” level during the exchange.

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