Recording of estimates using reference model attributes

Clinical (archive)
1

Hi everyone,

During a recent review of the Body weight archetype in the Norwegian CKM (http://arketyper.no/ckm/#showArchetype_1078.36.25), the following comment was submitted for the «Use» element :

“The text needs better specification of how the reference model is to be used to record estimates. There are attributes for “accuracy” and “precision” but it is not obvious how these could be used to explicitly record an estimate.”

This points back to (the Norwegian translation of) this paragraph:

“Can also be used for recording an approximation of body weight measurement in a clinical scenario where it is not possible to measure accurately body weight - for example, weighing an uncooperative child, or estimating the weight of an unborn fetus (where the ‘subject of data’ is the Fetus and recording occurs within the mother’s health record). This is not modelled explicitly in the archetype as the openEHR Reference model allows the attribute of Approximation for any Quantity data type. At implementation, for example, an application user interface could allow clinicians to select an appropriately labelled check box adjacent to the Weight data field to indicate that the recorded weight is an approximation, rather than actual.”

As far as I can see, the part of this relating to the reference model was added in revision 6.2 (http://www.openehr.org/ckm/#showArchetype_1013.1.399_2) in 2009. Almost the exact same wording is used in the Height/Length archetype.

Could anyone explain exactly how reference model attributes can be used to achieve this flagging of a quantity as an estimate?

Kind regards,
Silje Ljosland Bakke

Coordinator, National Editorial Board for Archetypes, National ICT Norway
Special Adviser, R&D dept, E-health section, Bergen Hospital Trust

Tel. +47 40203298

Web: http://arketyper.no / Twitter: @arketyper_no

2

Hi Silje,

We didn't use it so far, but there is an optional magnitude_status attribute that can contain values as:

"~"
"<"
">"
...

to indicate estimations and approximations.

In the serialized Object it should look like this:

<value xsi:type="DV_QUANTITY">
<magnitude_status>~</magnitude_status>
                             <magnitude>50</magnitude>
                             <units>mm[Hg]</units>
                             <precision>0</precision>
</value>

Best,

Birger

3

Thanks Birger, for your quick and informative reply! Now we can safely publish the Height/length archetype! J

4

You can also use the accuracy, which is a numeric e.g. +/-10%. Both can make sense, but probably not on the same measurement. Accuracy is for when the measuring method is quantitative but contains error. Magnitude_status was originally added to openEHR to deal with pathology results e.g. protein in urine etc where the measurement was approximate in some way, e.g. 'off the scale'.

But I think the values ~, <, > are perfectly valid and quite informative things to add to other kinds of measurements, including this example. Note that the presence of this in the quantity means it doesn't need to be explicitly archetyped.

- thomas

5

Hi Silje and all,

You can always click on the datatype icon (or the little arrow next to its name) in CKM to see some of the most important RM attributes for this datatype.

Cheers
Sebastian