Hi All
I got a question about the time in the observations, like blood pressure, Heart_rate, etc. There is no item in a Archetype that contains the time of the event.So, how it would be saved (i e time of the blood pressure or herat rate that is measured ). I know that in the HISTORY class there are some attributes for saving the time of the event. But as the Archetypes are our model for making templates and inserting data and there is no item to save the time in the observation,so how it will be saved?
You are not the first person looking for such attributes.
Archetypes are not designed to be the sole model for somthing like a screen template or form. You need to combine it with the stable reference model (RM) - that is what two-level modelling is all about. As you assumed correctly are in the RM classes HISTORY, EVENT and COMPOSITION (for the context). You will need to implement (or re-use the open source Java one) what is often called a “kernel” in openEHR. It brings the stable RM and the archetypes together. This component could be the basis to run and control (maybe even create) e.g. screen forms.
Hi Thilo
Thanks for the reply.
But there’s something cloudy in it for me.I mean when someone is entering gathered data in a template (as you said by bringing Archetypes and RM toghether) where this attribut will be saved whereas Archetypes are responsible to have content(like systiloc blood pressure, time, position, etc) related to a subject of
health.Because the time that blood pressure is 120/80 , is part of content.
I hope I have explained my question clearly.
archetypes assemble generic RM classes. The actual data will be saved in instances of these classes. The archetype restricts the endless RM class combinations to sensible and clinical meaningful ones.
The stable set of RM classes provide important medico-legal (e.g. audit trail) and technical (e.g. generic db storage) requirements that are the same across the whole health domain and most likely won’t change soon.
I think you (and others before) are struggeling with the “missing time attribute” because this part of the RM is currently not visibly exposed in the archetype editor or template designer. The reasoning behind is that such attributes are fixed i.e. not archetypable! There have been discussions about this issue and this will certainly be addressed in future generations of tools.
If we had to model everything like event series and timing in archetypes, then we would get in a real mess because everyone would do it in a different way. That’s why the reference model generically models important things such as the recording of the time of an event - so you don’t have to explicitly think about that every time that you want to model timing. The OBSERVATION class in the openEHR RM has a very nice model for events and time series so that you can just model your event without having to model the intricacies of timing over and over. What openEHR doesn’t do is have a time on every node like some other formalisms whether you like it or not - in this way, software systems ALWAYS know exactly where to find the time of an event and what it means.
When you need to, you can explicitly model a particular time or date - for instance if you have a look at the problem-diagnosis evaluation, you will see a number of different date/times modelled. However its important not to model things that are already in the reference model as you get all of that for free!
As far as the data instances go, what Thilo is saying is that the archetypes just specify which bits of the RM will be used for a particular data instance that represents some concept. This means that the RM models are there in the data so that you can use the timing elements of the RM.
Creating archetypes is easy, however creating good archetypes needs a little training.
You probably need to read the EHR RM specification – and about the observation in particular. Archetypes just say how to use these classes to represent the clinical concepts so the timing on the event is a feature of the event class in the reference model. The archetype just describes ‘pre-ordained’ events (like an interval known as paradox based on variation over an interval).