Hi,
Shouldn’t the BMI archetype on CKM be of type Evaluation? One does not observe BMI, it is a calculation.
openEHR-EHR-OBSERVATION.body_mass_index.v1
Thanks for your comments.
Bert
I think evaluation requires the interpretation from a professional. On a calculation there is no interpretation, the interpretation comes from the result of the calculation, like saying the patient is obese.
Good argument, I keep that in mind
Bert
I would say one needs both:
Evaluation: when calculating by the author the BMI-number using existing weight/height data
Observation: when reading/copying by the author aa a BMI-result from a source
Gerard Freriks
+31 620347088
gfrer@luna.nl
Also a good argument 
A good solution would then be, put it in a cluster, so it can be sticked into whatever is right for the situation.
Bert
from ehr_im
OBSERVATION (for all observed phenomena,including mechanically or manually measured, and responses in interview)
My interpretation is automatic calculations are included in “mechanically measured”.
Also
EVALUATION (for assessments, diagnoses, plans, risks, recommendations)
I don’t see an evaluation in the execution of a numeric formula, but I can see it in the recording of an evaluation in terms of the result of executing the formula. Similar case the calculation of the mean systolic BP based on a series of events = 140 mmHg (is OBS), and stating “high BP” or “hypertension” is EV).
My ‘definitions’
Observation: a result obtained by an author using human senses
Calculation: a kind of Evaluation by a human or device using Observations and knowledge (rules, formula)
Evaluation/assessment: Interpreting observations caused by processes using existing knowledge
Diagnosis: Special case of Evaluation. The process pertains to processes in the Patient system.
Gerard Freriks
+31 620347088
gfrer@luna.nl
Kattensingel 20
2801 CA Gouda
the Netherlands
I think this is a case of putting too much weight into the names of the archetype classes.
Basically:
· OBSERVATIONs are used when you need a point in time event (or series of them) or an interval event with or without a math function, ie want the same thing done over and over again with the same protocol, or you need to specify the patient state.
· EVALUATIONs are used when you don’t need any of the above, and the use case doesn’t fit with ACTIONs, INSTRUCTIONs or ADMIN_ENTRY either.
BMI is evidence that is reached by calculation of measurements, it’s not a clinical assessment. Based on the BMI, you could draw a conclusion that the person is obese, which would be recorded in an EVALUATION archetype (typically EVALUATION.problem_diagnosis).
Thanks Silje,
to my personal opinion, I think this is the best answer, at least the first part. The second part consist of negation, I would like a more positive description about when to use an evaluation. That is per example in the third part of your answer.
I like to thank all for your considerations shared on this mailinglist.
Best regards
Bert Verhees
these days, systolic and diastolic are calculated by BP measuring machines that actually measure mean arterial pressure.
An Evaluation is meant to represent a clinical assessment or inference of some kind, including classification, diagnosis etc.
- thomas
HI All
The fact that BMI is derived from two other measurements does not make it an evaluation. It is objective and when it was measured, max, min, average etc are all of interest.
An evaluation is a clinical statement of persistent relevance. Silje’s example of Obesity or Malnutrition are good examples. There may be a date of onset but there may not be. Personality disorder is an example of the latter. Dates in evaluation archetypes tend to be specific to that concept.
Cheers, Sam
Sam,
I reserve Observation for all that can be observed by the five human senses.
All that is derived by, for instance, a calculation, or rules, or a thought process, is an Evaluation.
This means that sometimes BMI is read or heard and therefor an Observation.
Or derived using observed values like Weight and Body length and there for an Evaluation.
I disagree with the definitions as provided by Silje.
Each item in the EHR has an associated point in time, since life unrolls in time as does documentation.
A definition that is based on exclusions only is not correct.
E.g. 'Something is a bee, because it is NOT a lion, Not a tulip, and NOT a mosquito’ does NOT qualify as a correct sensible definition.
What are the formal definitions of Observation and Evaluation in the context of an EHR?
Gerard Freriks
+31 620347088
gfrer@luna.nl
Kattensingel 20
2801 CA Gouda
the Netherlands
It is clear to me.
Not only our senses observe, mostly we use devices to observe. Sometimes very complex devices, like MRI, their are a lot of calculations in those devices, billions of calculations.
BMI is something that often takes two devices to measure, but it could be possible to create a single device which does this. So in that case it would be an Observation? Than it will also be if not a computer does the math, but a human being.
To judge however if a BMI is a sign of obesity, that is subjective. For a normal person, a BMI of 28 could be obese, but for a weightlifter, because of all those heavy muscles, a BMI of 30 still is not obese. So that would be evaluations.
Bert
What are the definitions?
Gerard Freriks
+31 620347088
gfrer@luna.nl
Kattensingel 20
2801 CA Gouda
the Netherlands
Read for yourself Gerard:
Saying this, it comes to my mind that often complex devices, also supported by computers, AI-algorithms, etc, not only observe but also evaluate/interpret.
So what comes out of the machine can be a mixture of observations and evaluations, hard to distinguish, and also rather academical to distinguish.
Maybe the reference-model is in need of another term, that can be partly observation and partly evaluation. And when we have that term, it is questionable if that term shouldn’t have been there at the first place.
Bert
I read NO definition of Observation.
I see NO definition section.
A good definition is a text that precisely denotes a concept and is written such that the defined term can be substituted by that text without any changes.
A good definition is not using the concept name in its definition.
Gerard Freriks
+31 620347088
gfrer@luna.nl
Kattensingel 20
2801 CA Gouda
the Netherlands
Let us stick to one subject of a time, else the discussion will become confusing.
What is your good definition of Observation and Evaluation, on which base you disagree with what others write about it?
For those who are interested in the background…
the underlying design of the Entry types were the result of an epistemological analysis of kinds of information that could be generated in clinical work. That required an analysis of the ‘clinical cognitive loop’ as I now think of it, which is similar to a scientific investigation (theory building), but goes further and then intervenes in reality, based on the theory of what is going on.
So briefly, the types are:
-
Observation - data gathered, including what is called ‘subjective’ data, e.g. patient-reported pain. It is assumed that both manual and machine means are used to gather data, and that the data may be of unlimited complexity. However, the data are ‘about’ the one individual, i.e. the patient (patient’s kidney, skin, CV system, etc)
-
Evaluation - inferences made by human mind or machine, by comparing the individual data to the current knowledge base - i.e. standard medical knowledge, diagnostic guidelines, etc - any knowledge that is ‘about’ categories, e.g. ‘patient with high BP’, ‘patient with raised blood glucose 2h after challenge’, etc. These can be understood as some kind of ‘opinion’, since there can always be errors in matching the observation to the knowledge, or even knowing which observations matter and so on (think: episodes of House). Typical clinical words for Evaluation are ‘assessment’, ‘diagnosis’, but even just identifying a ‘problem’ is a kind of evaluation. An evaluation that has been made can be considered some kind of clinical decision on which actions can be based.
-
Instruction - request to various actors to perform specific actions, based on the Evaluation(s), typically medications, other therapies, education, further observation.
-
Action - record of actions actually performed.
-
Admin_entry - record of administrative statements recording passage of patient around the care system.
The actual data structures we defined for these types are in some cases quite structured, e.g. Observation, Instruction, Action. This was based on the idea that these kinds of Entry have data of a certain shape. For example, Observations are by definition time-linked samples in past time, so the data structure is a time-series. Additionally, the data/state/protocol triple format mimics the reality of measurement.
As we gained experience with these Entry types over the years, it became apparent that there are some grey areas, e.g. path labs and radiology can send back results containing ‘interpretations’ and so on. If we were to redo the analysis today, we might potentially have somewhat more flexible structures, and rely a bit more on archetyping to specifiy the epistemic category of each Entry. However, I would say that the current system has held up pretty well, and the grey zone is pretty small.
It should be additionally understood that concretely defined data structures are what make it possible for software engineers to build clinical software that can work with the data.
Compare this with software based on most of the extant message formats or other more freeform models - there is no support for even the most basic things like time-series of data, or state machine transitions of orders. While there are sometimes debates about whether some data item should be an Observation or Evaluation, once the choice has been made (at least for international or national archetypes), everyone has the same representation of that data, and software is guaranteed to be able to process its basic structures (time points, data/state/protocol etc).
So, of course what is there is not perfect, but it seems to have held up reasonably well, and new additions like Task Planning will make it better.
Here are some FAQs about the Entry types that talk about the grey zone etc.
- thomas
I don’t disagree that we may need a more subtle analysis in the future that deals with the supersmart machines that are now mixing pure measurement with interpretation. For now, I would suggest that the best dividing criterion for choosing Observation or Evaluation is to ask the question:
- is this information (only) ‘about’ the individual patient?
- YES => Observation- or does it contain inferences made by comparing individual data against knowledge of clinical categories?
- YES => Evaluation
if it seems to be mixed, e.g. a path result containing both the raw result e.g. microbiology ‘organism = giardia’ and an interpretation ‘probable giardiasis’, you have to consider using both an Observation and an Evaluation, or that only one of them is really relevant.
There is a good philosophical and practical reason to distinguish between Observation and Evaluation - Observations can be expensive to make, but are generally reliable. In difficult cases, Evaluations can be wrong, and need to be revisited. The EHR needs to be able to show the observational data distinct from subsequent interpretations so that an investigation for a difficult case can proceed efficiently.
- thomas