In our implementation of LOINC, we are sending all of the code components in the ORU HL7 message in OBX-3.2. Another group in our company has raised the issue where in the LOINC manual, the short name should be sent. In the HL7 2.5.1 Implementation Guide for Electronic Laboratory Reporting to Public Health, example messages show both short names and full components. My questions are:
1. Which one should be sent?
2. Did this change recently? If so, when did it change?
The short answer is that there is no ‘right’ answer for all circumstances.
Historically, we (LOINC) have recommended the use of the ShortName (over the colon-separated fully-specified name) in HL7 messages because it fit within the space allocated by most lab reporting systems (30 characters), would work as a column name on a flowsheet, and used common acronyms people would recognize. I think the fully specified name has more instances of ‘reserved characters’ like “^” and “&” which would need to be properly escaped, and we’ve heard a few folks mention difficulty with their systems doing this…though there is a clear cut way to do it.The base HL7 2.x standard doesn’t specify (and actually would be valid if you sent your own label as the display name associated with a LOINC code — something we don’t recommend). More recently we developed (and now have fully-populated) a Long Common Name. These are probably more understandable to human readers and might be preferable, but they can be quite long, so some systems may not accomodate. The HL7 implementation guides for certain use cases (e.g. ELR to public health) may or may not constrain the freedom of the base standard with respect to the preferred display name, thus leaving the choice up to the exchanging partners. This has also come up in the recent EHR certification testing specs, and we have made comments to NIST about it. This display name issue is being discussed as a project in the HL7 vocab workgroup because it is not unique to LOINC.
So, if there are no other constraints, I’d recommend the Long Common Name, but the Short Name or Fully-specified Name are valid in most contexts too. Since the Long Common Name has only recently reached a state of moderate maturity, we haven’t yet updated the LOINC Users’ Guide, but we probably will revise it to include a summary of the above sometime in the near future. We also definitely recommend the simultaneous messaging of the senders local code and local name (in addition to the LOINC code and Name) to facilitate debugging and detection of mis-mappings.