Sunday, February 18, 2007

Connecting for Health: A Glimmer of Light

Interesting news from the United Kingdom, where so much effort and treasure have been expended in the last two years in attempting to base a national system for health information exchange on HL7 v3 messages. The HL7 approach is based on the requirement that a new kind of message should be created for each of the many separate kinds of information transmission. Once again, this requirement has proved economically unfeasible to implement in a non-toy environment.

Miracle of miracles: the UK National Health Service has decided not to use HL7v3 for clinical messages.

The NHS describes this as "a small technical change that better facilitates the carrying of fully coded messages in some circumstances." This is, however, to downplay the huge significance of the choice. It means that the NHS, after huge efforts on the part of some of the best minds in health IT, has found that HL7v3 messages are just too painful and difficult to use. Connecting for Health will use instead the Clinical Document Architecture (CDA), which is the HL7 document format, and which -- in version 1 at least -- is one of the few well crafted pieces of HL7 artefact. This means, in effect, that CfH is moving to a single generic message that is able to take anything as payload. This is a complete dis-endorsement of the HL7v3 message approach by HL7's biggest supporter (by far) -- hence the attempt to downplay it politically.

Unfortunately, there are still issues remaining. CDA is a single-document specification; thus it has no provision for cross-document linking or for EHR repository versioning. CDA is heavily text oriented, and although it can store some structured content, the definition of that content at the entry level is limited to RIM types. Thus, we predict, many of the familiar problems of v3 will be thrown up once again.

1 comment:

Tim Benson said...

You obviously did not read my article carefully. NHS Connecting for Health has resolved to base future clinical messages on HL7 CDA Release 2 - not CDA velease 1 as you imply.

HL7 CDA Release 2 is an implementation of HL7 V3, which includes structured clinical data, using the HL7 Clinical Statement Pattern, together with an additional human-readable rendering of each part of the message. This is valuable for recipients with legacy systems who cannot yet process fully structured messages. As such, CDA Release 2, which became a standard in 2005, is an enhancement on earlier HL7 V3 messages, which do not have a human-readable component.