Lp Paper

Loren Pachuta
HL7 Version 2 Vs Version 3
HL7, also known as health level 7 is an all-volunteer non-profit organization that is involved in the development of international healthcare standards. The ultimate goal of HL7 is to standardize data and make efficient and seamless communication throughout healthcare industry. The term HL7 is associated with the standards that have been created by the organization. There are two well-known versions of HL7, version 2 and version 3. As of now version 2 is used by the majority of HL7 users. There are both positive and negative aspects of making the switch from version 2 to version 3.
HL7 is one of many American National Standards Institute (ANSI) accredited Standards developing organizations involved in the health care industry. The name Health Level 7 comes from the seven levels of the Open Systems Interconnection model. Level 7 is the application level. The HL7 organization was founded in 1987 and the American National Standards Institute (ANSI) recognized it in 1994. HL7 is used to create a standard in hospital information systems. The standards are designed to improve care delivery, optimize workflow, reduce ambiguous data, and make the transfer of information a smooth process between hospitals, government agencies, and healthcare providers. Before HL7, every interface between systems was custom designed and required a significant amount of work. In earlier years there were less interfaces because they were so expensive. Since about the year 2000 the cost of interfaces has significantly been decreasing over the years and the quantity of clinical interfaces is growing which presents a desperate need for standardization across them.
A HL7 message is a way to transmit data between disperate systems. Each message consists of a group of segments in a defined sequence. Message types are identified by a 3-character code and are used in conjunction with a trigger event. A trigger event is a real world event that initiated communication and the sending of a message. Trigger events are sometimes referred to as message events. Both message types and trigger evens make up the MSH-9 field of an HL7 message. For example an MSH-9 field containing ADT-A01 means that ADT is the message type and A01 is the trigger event. Messages combined with different trigger events produce different messages. There are fifty-one trigger events that are associated with the ADT message type. There are tons of different message types in HL7. Some popular message types are ACK(General Acknowledgement), ADT(Admit Discharge Transfer), BAR(Add/Change Billing Account), DFT(Detailed Financial Transaction), MDM(Medical Document Management), MFN (Master Files Notification) and ORM(Order: (Pharmacy/Treatment). Another segment of the HL7 message is dedicated to the patient identification.
Users of HL7 are typically divided in to 3 segments or groups of people. The first group is the clinical interface specialists. Clinical interface specialists deal with moving clinical data, creating tools that make it possible to move the clinical data, and creating clinical applications that need to share or exchange data with other systems. They are responsible for moving clinical data between applications or healthcare providers. Another group is the government or other politically homogeneous entities. These types of people look toward the future of sharing data across multiple entities or in future data movement. They have the greatest interest in mandating a messaging standard. The third and final group is the medical informatists. They work within the field of health informatics. Health informatics is the study of logic of healthcare and how clinical knowledge is created. These types of users seek a form of hierarchical structure or healthcare knowledge, terminology, and workflow.
HL7 version 2 came out in 1989 and is still used today. The most popular and commonly used versions are 2.3 and 2.3.1. At least 75% of HL7 users are using one of those two versions. HL7 version 2 was for the most part, created by the users of applications (the clinical interface specialists). The developmental process was very user lead and real world focused. The initial goal of HL7 2 was avoiding large amounts of custom expensive coding and to create something that didn’t have 100% custom interfaces for everything. The group loosely defined an implied data model partially because they didn’t have a standards history to rely on. At the time there was a big issue with a lack of interest from the major application vendors.
The biggest complaint about version 2 is that it provides loose and optional standards and is too customizable. It was obviously better than what they had previously but the loose standards can lead to discrepancies and miscommunication in HL7 interfaces. Chances are it is preferred by a users (clinical interface specialists) standpoint but is less favorable by government officials as well as medical informaticists. There are no precise standards leaving things too ambiguous at times. HL7 version 2 is also not inclusive of international needs. It needs to support the need for local variants. Although any specific version 2 is compatible with each other, there is no compatibility with version 3. Defining a detailed list of items to be discussed and negotiated before interfacing is a required aspect of version 2.
HL7 version 3 started development in 1995 and did not come out until 2005. It is XML based. Version 3 is based on a formal methodology and object oriented principles. There is a uniform set of models. 90% or more of the interface is predefined. The new standard is an explicit data model, clear definitions and less flexibility in individual message elements, which was done to create a stricter standard and overall less complicated interface for users. There are formalisms for vocabulary support and support for large-scale integration. Version 3 also has an expanded scope to include community medicine, epidemiology, veterinary medicine, and clinical genomics.
HL7 version 3 is only used by a very small percentage of HL7 users. As of now people currently using HL7 version 3 are considered to be the early adopters despite the fact that it has been in existence for a decent amount of time. It is popular among physicians in the Netherlands because they never used HL7 version 2. Government entities have begun to plan on using it to create interfaces between systems that have previously been separate. Healthcare entities in Europe, Canada, and Germany have launched initiatives to implement version 3. “The Canadian Institute for health information has some localization standards produced for version 2 primarily in the area of Claims and Reimbursements.”(Corepoint Health 11). Many clinical software applications are being replaced and upgraded in the United Kingdom and a national exchange spine is being built. Most of the reasoning for adopting version 3 is the users lack of version 2 or government forcing the upgrade to version 3. Another reason for adopting version 3 are to use it for applications without legacy communication requirements. Some examples include the US Centers for Disease Control, National Electronic Disease Surveillance System and the United States Food and Drug Administration’s clinical trials reports.
There are quite a bit of differences between version 2 and version 3. Version 2 reflects the complexity aspect of healthcare. Version 2 provides 80% of the interface and a framework to negotiate the remaining 20% interface by interface where as version 3 provides 90%. Version 2 is compatible with any type of version 2. Version 3 is more of a true standard and less of a framework for negotiation. The model-based standard of version 3 provides more consistency. Application roles of version 3 are well defined and have significantly less message options. In the long term version 3 is less expensive to build and maintain long-term interfaces. Despite the significant differences between version 2 and 3 there are still some similarities. Both versions are still growing. Some are starting to use version 3 and version 2 is still growing in usage. The biggest reason people aren’t switching to version 3 is the problems that go along with upgrading. Because they’re not compatible with eachother, it is an extremely difficult process to upgrade from version 2 to version 3. The process of changing would involve both maintaining version 2 while simultaneously converting everything from version 2 to be compatible with version 3. People are also less likely to start out with version 3 when it is only used by such a small percentage of all of the HL7 users in the world. The whole point of HL7 is to have standardized data that makes for seamless communication. The fact that so few people use version 3 also gives users of version 2 uncertainties that version 3 is the future and worthwhile. It would be difficult to use version 3 while the majority is still using version 2 when they are not compatible with one another. From the financial aspect alone, it is fairly certain that there is no way that version 2 will ever disappear. I don’t see a substantial amount of people switching to version 3 without the help of the government mandating it as a standard and offering assistance with the transition from version 2 to 3. It would be extremely costly but in the end it would lead to easier and faster communication and less headaches in the future once the transition was complete.

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"HL7 Resources | Corepoint Health." Healthcare Interoperability & Workflow Management Software | Corepoint Health. Corepoint Health. Web. 09 May 2011. <http://www.corepointhealth.com/resource-center/hl7-resources>.

"The HL7 Evolution." The HL7 Evolution. Corepoint Health, 2009. Web. 20 Apr. 2011. <http://www.corepointhealth.com/sites/default/files/whitepapers/hl7-history-v2-v3.pdf>.

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