Strengths of HL7V3.0

Optionality -HL7 version 3.0 has very little optionality which is one of the weaknesses of version 2.x. The RIM which is the basis for version 3 has no concept of optionality. The need for a value in the message is defined by trigger event rather than the data definition. This has led to better message definitions. Optionality in version 3 is replaced by “Conditionality” which means that the presence of a data field in the message may be allowed or not depending on the value of another field..

Model based - Version 3.0 is based on an object oriented model; Reference Information Model (RIM) to create message specifications. The model provides an explicit representation of the semantic and terminology relationships that is present in the information present in the fields of HL7 messages.

Conformance - HL7’s version 3.0 is primarily intended to be a stable and definite standard which will allow vendors to conform to a universal standard. This will allow regulatory agencies and local HL7 bodies where applicable test the applications to an agreed standard and provide a conformance certificate to the vendor.

Technology independent - Version 3 introduced the concept of “Implementable Technology Specification (ITS)” which describes the process of instantiating a message from its definition. Currently XML is the widely used and probably only one ITS available publicly. But unlike V2.x; HL7V3.0 ITS allows other technologies to be used for messages e.g. UML ITS, JavaBeans etc.

Electronic Health Record - HL7 version 3 offers a much more efficient method to communicate information between clinical systems by providing the context of information in the messages which is not possible in version 2.x. It also provides the ability to collect clinically coded information for the purpose of maintaining Electronic Health Record for sharing clinical data consistently across organizations. Version 3 is emerging as the standard of choice for creating national EHR’s due to the level of semantic interoperability provided by it.

Localization and Refinement: HL7 Inc allows a balloted HL7V3.0 specification to be further constrained for region specific profile aided by a HL7 Inc Affiliate. This localization of messages allows quick deployment of HL7V3.0 for an organization or region to meet their specific needs.

Strengths of HL7V2.x

Strengths of HL7V2.x

Mature Standard – HL7V2.x emerged as a mature stable standard in healthcare informatics after the specifications went through series of review iterations and modifications to cater to the needs of market. The HL7V2.x specifications are currently available and ready for use and easily implementable. A large number of existing applications are HL7V2.x conformant.

International Standard – HL7 has international affiliates in around 28 countries covering all major countries. It has emerged as the dominant clinical information standard in these markets. Majority of the HL7V2.x specifications including HL7V2.3/2.4 have been classified as ANSI accredited standards. HL7V2.4 is now being proposed as ISO standard. Apart from this some countries such as Germany have legislations that stipulate use of HL7V2.x.

Backward Compatibility - The biggest advantage of HL7V2.x is the ability of different versions of HL7V2.x to interoperate with one another. The rules for compatibility between different versions (e.g. V2.3.1, V2.4 and V2.5) have been documented in the specifications. These rules describe the transmission and receipt of messages and converting their contents to data values with full backward compatibility between all HL7V2.x versions.

Optionality - The use of optionality in HL7V2.x messages is helpful in gaining consensus and documenting compact specification. If a data field is declared optional within a segment then the segment can be re-used in different messages without defining a new segment which requires similar data fields. However there is a wide misuse of this optimality which will be discussed in next section.

Message Size: The chief virtue of HL7V2.x message specification is that its syntax is quite compact and hence the size of the message is minimal. This brings a huge benefit to the economy of bandwidth