On 18/05/2016 12:24, Ian McNicoll wrote:
Hi thomas,
See https://openehr.atlassian.net/browse/SPECPR-96 for discussion on
this. Medication dose and quantities need both SI units and otherwise.
The current restrictions make the modelling much clunkier than is
necessary IMO. I'm not clear why strict adherence to SI is helpful in
this context. Surely part of the point of a health orientated ref
model is to make life easier and medication dose units are a critical
type of quantity in this domain.
I was reviewing that (good statement of needs). The issue isn't SI units
- there are lots of non-SI units in UCUM. The issue is that units of
doses are not scientific units, and can't be represented the same way.
So we shouldn't expect our models of the latter to work properly for
dose units.
Of course I agree that we should make life easier for developers,
systems etc, and also that we have not really done so.
The more I think about this issue over the years, I mostly come to the
same conclusion: we need a special Quantity type that models exactly
what is needed. E.g. something like
class DoseQuantity
unitForm: DvCodedText // type of physical dose entity
tablet, capsule, puff etc
unitAmount: DvQuantity // how much is in a `doseForm` unit
e.g. 5mg
doseCount: Integer // how many items of `doseForm`
to deliver
doseAmount: DvQuantity { // total amount of substance delivered
to patient
Result := doseCount * unitAmount
}
end
Note that this does not include the actual substance, e.g. morphine or
whatever.
- thomas
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