Representing HbA1c result (mmol/mol) in AE

Clinical (archive)
1

Hi,

Any idea how to choose mmol/mol for HbA1c result using DV_QUANTITY in Archetype Editor?

It used to be a proportion (%) but now the international agreement is to use this unit which does not come as an option. Wonder if I exists in UCUM?

This is such a commonly used Lab item – I’m sure someone else must have hit the issue.

Cheers,

-koray

2

Hi Koray,

UCUM is extensible, you can define new units as long as you follow its syntax. In this case you are lucky, as mmol/mol (MilliMolesPerMole) is already used as UCUM unit. You can check it here:
http://www.hl7.de/download/documents/ucum/ucumdata.html

I think I also added all these units as valid UCUM units on LinkEHR

Imágenes integradas 1

Which is represented in ADL as:

C_DV_QUANTITY <
property = <[openehr::507]>
list = <
[“1”] = <
units = <“mmol/mol”>
magnitude = <|0.0..200.0|>
precision = <|0|>

Hope this helps :slight_smile:

3

Hi,

Any idea how to choose mmol/mol for HbA1c result using DV_QUANTITY in Archetype Editor?

It used to be a proportion (%) but now the international agreement is to use this unit which does not come as an option. Wonder if I exists in UCUM?

This is such a commonly used Lab item – I’m sure someone else must have hit the issue.

Cheers,

-koray

4

Hi,

Would it be possible to do a general update of the units used in the Archetype Editor? There are some symbols (like “°”) which apparently are not UCUM compatible and aren’t recognised by the CKM. Also, some unit symbols (like “gm” for gram) aren’t compatible with correct SI symbol use (in this case should be just “g”), and some groups/units like “µmol/L” (amount/volume) or “g/L” (mass/volume) aren’t there at all.

5

Hi,

Just to put some context to this:
I have implemented a UCUM units validator in CKM and also discovered that some of the units in AE should be updated.
This will be deployed with the next release of the openEHR CKM instance as well.

The units file in AE that Peter mentioned can have two entries for a unit: The one used in AE for display purposes (which could be °) and the corresponding expression in UCUM.
But I see two problems:

  1. The UCUM units are not set everywhere where it is required in this file.
  2. Unfortunately, even if a UCUM expression exists, it doesn’t seem to be used when AE serialises the ADL (e.g. still uses ° )

BTW: µmol/L is umol/L in UCUM

Cheers
Sebastian

6

Hi Koray / Peter,

I have created an Issue for this
http://www.openehr.org/issues/browse/AEPR-30 and have attached an
updated PropertyUnits file which allows for Amount (mole) / Amount
(mole) and also changes the 'unit' for Quntified real numbers which
have an empty unit from "" to "1", inline with UCUM and the java
parser.

Ian

7

Hi Sebastian,

I have looked a bit further into the AE code and I can't see the 'UCUM
override' attribute being picked up anywhere and I can see this as
being tricky to change and maintain.

My suggestion is that rather than trying to implement the 'UCUM
override' that we simply edit the propertyUnits.xml 'Text' attributes
to use official UCUM units. I think this will be much quicker to
correct and maintain.

Ian

8

Hi Ian,

That may be the best way, but it increases the problem of how you deal with the old units when an archetype is loaded in AE that has these units.
Ideally, they would be automatically converted, but of course that is trickier.

Cheers
Sebastian

9

Fantastic Ian - works for me now.
Many thanks

Cheers,

-koray