Re: [Gnumed-devel] clinician input wanted: how to implement "coding"

[James Busser]

> I am still looking for more use cases defining genuine
> *medical* desires.

I was thinking about how we assess severity or risk or prognosis from data and 
how coding may better enable that.

The Body Mass Index (BMI) is derived from the patient's weight (in kilos) 
divided by the square of the height (in meters). For GNUmed to calculate this 
for us for any patient, we may want GNUmed to be able to:

- locate for a patient, from in the measurements table, a weight (if one can be 
found) but GNUmed also needs to determine if this weight is in kilos or other 
unit (pounds) and, if in pounds, convert it. I cannot recall whether LOINC is 
so specific to also specify the units of measurement or if GNUmed would have to 
consult a "units" field.

- locate, for the patient, a height and resolving the same issues as to units 
(metres vs centimeters vs inches vs feet & inches)

- recognize that there exists more than one LOINC for certain measurements, for 
example weight coul dbe while NPO or else with or without clothes or maybe 
there are also some other kinds of weight

- decide how to deal with the fact that a measurement could be "old" and 
therefore a BMI could be based on a combination of a weight that was two months 
old (because it was not measured at every visit) and a height that was from 2 
years ago (because the height is documented even less often). Accordingly this 
"BMI" could be formatted so as to visually warn the user about the dates for 
example appending in parens the date of the most recent element and/or the 
oldest element

- it might be desirable to graph the BMI over time (based on a series of 
weights)

- another good example would be cardiovascular risk scores which are based on a 
combination of age and sex and family history and blood pressure and laboratory 
measurements. However even if we would wish to "submit" these data to a 
calculator and query the result we would need a coded way to designate the sex 
which is not in all languages "M" and "F" and also the family history.