NEHTA Clinical Documents: How not to represent an MRN

Jul 2, 2013

The FAQ about how to represent an MRN, my prior post and the forthcoming handbook for representing Australian identifiers all agree that MRNs are represented like this: ````


So you need an OID that represents the system that allocates the medical record numbers, and you have to get it from somewhere.

But where?

Well, there's an example in the SHS CDA Implementation Guide:
    

What this is trying to say is that the organisation identified by the HPI-O "8003620000000541" has a system that issues medical record numbers, and it has issued "542181" to this patient.

Only, this is not valid - the OID "1.2.36.1.2001.1003.0" has the definition "An identifier issued by the HI Service - IHI, HPI-I, or HPI-O." - but the root here doesn't identify "an identifier". Rather, it identifies a system managed by the organisation identified by that HPI-O. Misusing identifiers like this is what gets implementations into trouble, and systems should not copy this example.

Fortunately, there is such an OID for an HPI-O based Organisation Medical Record Number:

 <id root-=”1.2.36.1.2001.1005.29.[HPI-O]”  extension=”[MRN]”/> ````

Note that this OID is provided as a default option; if the organisation has some other OID to use to identify the MRN, then that OID should be used instead.