[Gnumed-devel] coding systems

[ihaywood]

I've got an empty booking now and a proposal for coding systems, which is an 
integration of some ideas from various people which have been floating around.

single table

create tables code
(
     fk_coding_system integer references coding_systems (id),
     code text not null,
     description text not null,
     synonym boolean,
     popularity integer,
     fk_population integer references population (id),
     soap_cat char check (soap_cat in ('s', 'o', 'a', 'p')),
     unique (coding_system, description)
);

synonym is true if the description is exactly interchangeable with the code. 
False if it is a further refinement/specification of that clinical concept.
(this is the equivalent of Horst's clinical thesarus)

The idea is a whole range of codes are available for the notes entry widget:
LOINC for measurements (BP, glucose, height, weight), MBS for procedures, ICD-
10 for diagnosis and ATC for meds.
Plus we have some "whimsical" or "bespoke" coding systems, such as referral 
disciplines, forms, anatomical drawings and patient handouts.
When a code is selected from a drop-down list, the middleware asks the GUI
layer if a popup widget exists for that coding system, and displays it if it 
does.
The widget is passed code.description, which it can use to pre-fill one or
more lines, for example we may have
Amoxycillin : synonym=True as it exactly matches the ATC code; and
Amoxycillin 250mg QID for 5 days: synomyn=False, it "overspecifies" the code
This is passed to the prescribing widget (because it's mapped to the ATC 
coding system), which is now ready for prescribing as it can parse the string

This allows users to quickly build up favourite "recipes" of drugs/test 
groups/etc.

code.population is used to add some "common sense", so for children I only get
amoxycillin syrup, for example.
In the SOAP widget only codes from the relevant soap_cat are show, in free 
text the reverse (soap_cat of the code is used to tag the text)

Comments please

Ian