Let me try and clarify the time aspect of the ontology... the question
is not that time doesn't relate to all Entry types. The question is how.
In the Clinical Investigator Ontology Sam and I constructed, there are 3
temporal upper level categories
* history - i.e. information relating to reality the way it was in the
past
* opinion - thoughts formulated at the current point in time based on
what has gone before, and/or what is known so far
* instructions - concrete statements about what should happen in the
future
Obviously these categories were not primarily named based on the
temporal aspect, but nevertheless they are based on temporal
considerations. They correspond relatively well to the epistemic
categories described in Sowa's upper level ontology
<http://www.jfsowa.com/ontology/toplevel.htm> as follows:
* history = Sowa's 'history' category, i.e. a proposition about an
occurrent, including anything that can be observed about the state
of the subject at a point in time
* opinion = Sowa's 'description' category, i.e. propositions about a
continuant, normally the subject of care. A diagnosis of 'Diabetes'
for example is saying that the patient John Smith (a continuant)
organism includes the diabetes process as part of it
* instructions = Sowa's 'script' category, which is itself an
occurrent representing time-based sequences of events, including
conditional decision points
The first and last of these categories are considered by Sowa to be
occurrents, i.e. time-related while the second is not. This seems pretty
clear.
Now consider the diagnosis archetype (an instance of the 'opinion' aka
'description' type)... it contains the main 'proposition' - i.e. the
identified index condition, diabetes or whatever - and a bunch of times
/ dates / durations / other descriptive details. So how is this not
time-based? Well we need to consider that what this information is
really doing is drawing a picture of temporal disease course, in terms
of these dates and times and durations. These are a way of qualifying
the main statement of Diabetes - it is recent, severe, intermittant
(symptoms) etc?
So why does temporal aspect this matter, practically speaking? For the
very simple reason that 'history', i.e. past time, is linear, i.e.
representable as a series of events / states; instructions are future
time, and therefore unavoidably have a branching, conditional nature
e.g. ICU insulin management protocol containing items like: if blood
sugar drops below 130 mg/dl, drop dosage. So the data structures for
historical data - Observations and Actions are unavoidably different
from those for Instructions, which are more like a set of statements,
conditions, etc (the structure can be quite complex). And Evaluations
(we could have named this one better) has neither historical nor
future-instructional nature, but instead the structure of a description
or set of statements (thoughts, ideas) about something else - in other
words, it could be any structure, so we just use a tree. If we
subdivided (as indeed we did in the paper), we could posit a number of
more specialised data structures.
See here
<https://www.google.com/url?q=http://ontology.buffalo.edu/medo/Disease_and_Diagnosis.pdf&sa=U&ei=AUXjT7KtCsit0QWkh6CLCg&ved=0CAUQFjAA&client=internal-uds-cse&usg=AFQjCNFu8-NLJOPGBMQlgg2BFOlcOqwUag>
for Smith/Ceusters/Scheuermann on an ontology for disease course and
diagnosis, in which they identify the same categories of information
more or less - clinical picture / diagnosis / plan.
So to summarise, it came down to finding categories on which /health
information data structures /- i.e. information models - could be based
that would work reliably for most if not all of medicine. Now, having
used these categories for some years, it turns out that they are
remarkably stable. I know that the grey-zone debate on
Observation/Evaluation will continue for ever, but if one steps back for
a second, what you see is that for /most types of clinical /data, it is
obvious which category to use. Most of the archetypes for these types
are not really in question. Further, noone has identified (to my
knowledge) a strong contender for any new kind of category (excepting
for sub-categories of AdminEntry, which will probably appear one day).
I think the main thing we got wrong was naming 'Evaluation' too
narrowly, when what we needed was a name that means 'what the clinician
thought' (if we had used Sowa's 'description' category I am sure we
would now be having arguments about why someone was using a
'description' to record a 'diagnosis'!). We would know we had gotten
things radically wrong if now, 5 years later, it were clear that say
another 5 or 10 data structure types were needed.
If indeed we managed to get this sort of right (for now), it's only
because we had 3 previous attempts (GEHR 1992-95; Australian GeHR
(1997-2000), first draft of openEHR (pre-2005)) where we got it wrong.
This is a hard problem to solve. In HL7v3, it was attempted with the
'mood' code, which is certainly a reasonable starting point
philosophically, but doesn't in the end help you get the right data
structures. This is well known in HL7v3 as a difficulty (and I am not
criticising for that, as I say our own little effort was 10 years in the
making).
The really amazing thing is that traditional epistemological categories
are of such little help. Divisions of a priori / a posteriori / how-to
are only vaguely useful (we used them and gave up on Aus GeHR), and yet
to a clinician, the differences between the observation of blood glucose
over 9mmol/l, Dx of diabetes mellitus and insulin care plan for glucose
management are crystal clear.
I don't doubt that something better is possible in the future, but I
think for now some finer adjustments on the current ontology and data
structures will be of most practical help.
- thomas beale
On 21/06/2012 13:37, Gerard Freriks wrote:
> Sam,
>
> According to me:
> - Observations have in reality points in time or ranges attached to it
> - As do Evaluations about processes in the patient system they have
> in reality times attached to them. Inferences are made at a point in
> time, but relate to inferred processes that come and go, or are
> believed to be present, or not, during a period of time.
> - As do Instructions
> - As do Actions
>
> Time is never is a discriminating factor that sets Observations apart
> from the other Entry types.
> *
> *
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