Introduction

From Hl7book

Contents 1 Introduction 2 The organization 3 HL7 Standards 3.1 Choosing the applicable standard

Introduction

Health Level Seven (HL7) HL7 refers to either to an international all-volunteer, not-for-profit organization involved in development of international healthcare standards, or to one of the specific standards created by the organization. HL7 creates open standards for the exchange, management and integration of electronic healthcare information through the collaboration of an international volunteer community of healthcare subject matter experts and information specialists. HL7 promotes the use of such standards within and among healthcare organizations to increase the effectiveness and efficiency of healthcare delivery. The standards, which support clinical practice and the management, delivery, and evaluation of health services, are the most commonly used in the world.

Such standards or guidelines are an agreed-upon set of rules that allow information to be shared and processed in a uniform and consistent manner. Without data standards, healthcare organizations could not readily share clinical information. Theoretically, this ability to exchange information should help to minimize the tendency for medical care to be so geographically isolated and highly variable.

The organization

HL7 Standards

The HL7 organization creates standards in a number of categories:

• Messaging, or more generically the exchange of healthcare data between applications
• Documents,

The list of products is typically as follows:

• HL7 version 2
• HL7 version 3
• Clinical Document Architecture (CDA)

Choosing the applicable standard

Given that HL7 defines a messaging as a well as a document standard, which could convey more or less the exact same data: when should one use messaging and when would the use of documents be more appropriate?

• Messages are generally used to support an ongoing process. They convey status information and updates related to one and the same business object. In such situations the latest version of the data is of importance, historic versions of one and the same object are generally not of importance apart from logging and auditing purposes.
• Documents are persistent in nature and tend to be used once the process has run its course, i.e. once the actual process is done. The underlying use-case for the use of the data is a different one: a subset of data, selected for use in a transfer of care scenario is stored for use in a persistent manner. Note that the transfer of care may happen at some point in the future when the patient is being treated again.

Typical examples include referral letters or lab reports in the form of documents. A physician makes a selection out of all of the data available and generated during the process (which was supported by messages) and sends that subset to another healthcare provider. The use of documents is often associated with a transfer of responsibility. the creation of a general clinical summary (as is done in some countries) which is stored on a centralized server for long term use is also a kind of transfer of responsibility; in this case a transfer to an as-yet unknown colleague who may be treating the patient in another part of the country or on an emergency ward.

And if one uses messaging, when would one use HL7 v2, and when would one use HL7 v3?

• As with most things in life: if it ain't broken don't fix it. This means that the HL7 v2 messaging interfaces as they're being used today (mainly within hospital organizations) are likely to be used in the foreseeable future. HL7 v2 interfaces are mostly used to support a number of basic processes and rarely use complex modeling of clinical data. HL7 v2 interfaces tend to be peer-to-peer related, with interface variations being translated by communication servers. If one only has to deal with a limited number of systems the strategy of translating between dialects is a viable one.
• If one would like to use messages to convey information between organizations, or on a larger scale with a multitude of healthcare providers within a region/country, then HL7 v3 is a more suitable standard as it specifically caters to the need of distributed environments. The fact that on a nationwide scale one simply can't know the dialect of the receivers any more means that the the stricter modelling and conformance features of HL7 v3 are a definite advantage.