Stream: implementers
Topic: Max dose per course
Rik Smithies (Oct 09 2018 at 16:55):
How to express this? If the course is not precisely time limited and has more than one administration, and can be given more than once per lifetime, then none of the max dose options in Dosage work. (Unless "course" is used as a time unit...)
Lloyd McKenzie (Oct 09 2018 at 17:37):
Course = disease episode? Duration of prescription?
Rik Smithies (Oct 09 2018 at 17:50):
duration of treatment e.g. 500 micrograms 2–4 times a day until symptoms relieved, maximum 6 mg per course
Rob Hausam (Oct 09 2018 at 18:46):
I don't know if you have a definition for "course", but I assume that it would be something like "a contiguous period of regular administration" (probably with a particular therapeutic goal in mind), with individual courses separated by some "sufficient" (however that's defined) intervening time period between them. The sufficient intervening time period would likely be dependent on the usual duration of therapy, the drug half-life, etc. That's my supposition at the moment, anyway. And then still to figure out how best to express it in FHIR ...
Lloyd McKenzie (Oct 09 2018 at 21:20):
That sounds like a maximum over the course of the order - that sounds like a reasonable extension.
Rik Smithies (Oct 10 2018 at 09:08):
@Rob Hausam yes that's exactly it, from my understanding anyway. @Lloyd McKenzie presumably a modifier extension? Next question is how to say that there is this "sufficient time" between the courses. The full request includes "do not repeat course within 3 days". Can that be done with timing? Another modifier extension I would assume.
Rob Hausam (Oct 10 2018 at 11:43):
Hmm. I was trying to think how it might not be a modifier extension, but I guess it probably must be, as if you ignored the extension you would interpret the total order differently and you would be missing a potentially critical constraint which could be a patient safety issue.
Lloyd McKenzie (Oct 10 2018 at 14:46):
It wouldn't be a modifier extension. It doesn't change the definitions of any other elements in the resource. (It is something you'd presumably want exposed in narrative though.)
Rob Hausam (Oct 10 2018 at 14:53):
That was my first thought. I started to say that and then I talked myself out of it. :)
Rob Hausam (Oct 10 2018 at 15:04):
The conclusion that I talked myself into is that this rule probably applies here: "If it is not safe for an application processing the content of the resource to ignore the extension it SHALL be represented differently using a Modifier Extension". I'm not seeing that it will be safe (at least for certain medications and situations) for an application to ignore this extension.
Lloyd McKenzie (Oct 10 2018 at 15:06):
Modifier has nothing to do with safety. It has to do with changing the meaning of elements. The best way to think about it is whether a decisions support system that only processed and cared about the core elements would have its results invalidated by the introduction of the extension
Rob Hausam (Oct 10 2018 at 15:10):
If that's correct, then it seems to me that we need to change (or remove) the 5th bullet under Notes in http://build.fhir.org/extensibility.html.
Lloyd McKenzie (Oct 10 2018 at 15:13):
It certainly needs to be revamped. Can you submit a change request?
Rob Hausam (Oct 10 2018 at 15:14):
yes
Rob Hausam (Oct 10 2018 at 16:00):
Rik Smithies (Oct 10 2018 at 17:46):
I am a bit surprised that this isn't a modifierExtension because it could change decision support from "yes give" to "no had too much already", though that decision would perhaps only affect another instance of this resource type. Is there somewhere else to say "this is important you cannot ignore it". Is mustUnderstand still a thing?
Lloyd McKenzie (Oct 10 2018 at 17:49):
It's not a question of whether decision support might want to pay attention to the new element. It's a question of whether it changes the meaning of the other elements.
Lloyd McKenzie (Oct 10 2018 at 17:50):
You can certainly put mustSupport on it certain contexts - but there are lots of reasons why a system might pay attention to a prescription and not care about dosage at all.
Last updated: Apr 12 2022 at 19:14 UTC
