We have discussed this in our modeller meeting and we can’t think of any use cases where orders are given with different routes depending on dosage. The one exception is initial doses, for example misoprostol for induction of labour, where the initinal dose may be administered vaginally and subsequent doses may be given orally.
However this would usually be handled as a separate order, as part of an order set.
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There are other situations such as an order for antiemetic to be given prn, either orally or IM depending on whether the patient can tolerate an oral medication without throwing up. In the current modelling scenario, it would require two separate prn orders, one for each route.
The clinical purist in me, with a medicolegal bias, would prefer amount, timing and route all to be found in one place. Software could manage the apparent replication of the route, but in fact it would be more faithful in recording the deliberate clinical intent.
It would be interesting to investigate if separation of the route into a different part of the model could contribute to a clinical safety issue unless the software reminds the clinician to check the assumed route.
Always worth checking we’re in agreement. This is our modelling intent, but given the ubiquity of FHIR, working out where to draw the line where alignment turns to compromise can be grey sometimes and how to balance pragmatism vs purist approaches.
Anyone disagree?
I don’t think this would be necessary. The “Route” element in INSTRUCTION.medication_order has occurrences 0…*, so you could put in as many alternative routes as you wish.
As long as the assumption holds that 99% of orders have the same single route or same set of alternative routes for all different dosages and timings within that order, I don’t see how bundling route with dosage would be more faithful to the clinical intent.
It could be interesting to see the justifications for modelling it the way they have in FHIR. Anyone know where we can do that? Or who we could ask?
Different routes often require different doses - oral vs IM analgesics/antiemetics will require 2 orders.
Just as we record the actual term a clinician chooses from a value set, even if a preferred term is stored and used for persistence, I’m still curious about the investigating the medicolegal issues re ensuring that the complete order for how a drug should be administered needs to be explicitly recorded.
Also understanding the provenance of our model - where else is this design pattern used in parallel standards or are we isolated here?
I’m assuming we’re talking hospital settings here? When you’re into PRN injectable analgesics/antiemetics they would normally be titrated, not given according to a set dosage.
Sure. Do we have any legal frameworks to lean on in this level of detail?
Good question. The “Route” element was added to the INSTRUCTION.medication_order archetype by @ian.mcnicoll on 29 Oct 2015, with this set of references:
openEHR Foundation Medication archetypes http://www.openehr.org/knowledge
NEHTA's Therapeutic Good Use Data Group from the NEHTA Website http://www.nehta.gov.au
Intermountain Healthcare Medication order model, Personal Communication to Sam Heard by Dr Stan Huff.
Royal Australian College of General Practitioners. Fact Sheet: Medicines List. 2010.
At that time, FHIR was at DSTU2, and had Route as part of the “DosageInstruction” group within the MedicationOrder resource: MedicationOrder - FHIR v1.0.2. I.e. similar to today’s pattern only they’ve divided it up into separate resources. I don’t know how to find the references for FHIR resources.
The ‘complete order’ from a legal /safety perspective has to include the medication name and form and anything else, so you could argue that the FHIr Dosage is more disconnected in that sense.
THe background to this work was all pre-FHIR and came out of a whole bunch of prior art UK GP2GP , the NEHTA work, C-CDA, som nice data models out of University of Dundee and a lot of practical feedback from implementers.
I can sort of maybe see an equal argument for doing it the FHIR way and some potential downsides as discussed above, but I can’t see any compelling reason for changing things any time soon. The differences are trivial from a tech perspective, in terms of mappings. Once the full set of models are constructed in a template the final templates/profiles would look almost the same, and our models have been thoroughly road-tested in terms of applicability to prescribing systems, not just data exchange. We have many, many patient records running against the current models.
and FHIR is still a bit of a movable feast (which I agree with BTW), so may change again. Just don’t think this question is worth much time or effort right now. If the mapping was awkward that might be different but it is really pretty trivial to adjust between the two sets of models.
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Generally speaking, if it ain’t stated in the documentation of the specific resource page in FHIR, then it ain’t true 
I found this discussion in the FHIR Jira: https://jira.hl7.org/browse/FHIR-10066
I’m not sure I’m able to follow it, but to me the argument for moving ‘Route’ to ‘Dosage’ seems to be “it was this way in HL7v2”. 
THe examples that are in that discussion we can actually support as we do allow multiple routes.
Examples provided by Scott:
An example of PO/IV
Ondansetron 8mg orally or IV twice a day as needed for nausea
Really 2 orders:
Ondansetron 8mg orally twice a day as needed for nausea
OR
Ondansetron 8mg IV twice a day as needed for nausea (ignoring for the moment that it should be given over 30 min)
Here's a classic:
Compazine® (prochlorperazine) 5-10mg PO or 25mg PR bid prn n/v
And as 2 orders
Compazine® (prochlorperazine) 5-10mg PO bid prn n/v
Or
Compazine® (prochlorperazine) 25mg PR bid prn n/v
What we do not support is differential dosage/site/method instructions for each route. There are definitely some use cases for that but I have also seen guidance that suggests that this is not good prescribing practice, and I’m pretty sure I would have got a b*****ing from the nursing and pharmacy staff if as a junior I had tried to combine them, at least in a written ward medication order!! THey would have said, create separate orders for each route.
It feel unsafe to me but I think we need to seek guidance from pharmacy colleagues on best practice.
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There is one (very common) medication in perioperative medicine which is frequently ordered with multiple routes: Paracetamol
A typical adult prescription is Paracetamol 1g PO/IV/PR QID, with potentially severe consequences if it is administered simultaneously via different routes.
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Thanks Nathan! Paracetamol is sometimes ordered with multiple routes even on regular wards, where the idea is that the nurse chooses the most appropriate route at the time of administration. But I’ve never seen it ordered with multiple routes in one order, with different dosages based on the route?
Ah yes - I think that I misunderstood the problem sorry. We are talking about one particular situation - low bioavailability medications, where the amount of absorption of the drug differs significantly depending on the route.
This is tricky clinically, and even trickier to cope with on the information tech side. The bioavailability (which is usually estimable) really needs to be included as part of the model, because what matters from the safety perspective is the amount absorbed by the patient.
For example, a patient receiving 20mg morphine PO along with 5mg morphine IV is much more likely to be in good shape than one receiving 20mg morphine IV and 5mg PO!
In clinical practice, we do tend to only prescribe one form at a time with these meds for that safety reason. But it sure would be nice to be able to confidently prescribe these drugs via different routes and differing doses. This is however a 1% thing, as you say.
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Thanks Nathan, that makes sense. I’d be interested to see the current recommendations for handling this - two separate orders or one rather complex order? Btw, are these often regular orders, or usually PRN?
A mixture. They tend to be for dynamic situations where the patient may fluctuate between being able to take orally or not (the common perioperative situation), or have intermittent IV access.
It isn’t commonly done really, but it is done commonly enough that it really should be catered for.
For clinical safety, the absorbed amount of drug is the vital variable. I doubt that any current system takes it into account though (would love to be proven wrong)!
I think the commonest use case for this kind of prescribing via a choice of either Route A OR Route B, but not both, is in pain relief - making sure appropriate analgesics can be given as required. Post op is a common use case and it was routine for all my palliative care patients, back when I was a lass.
yup agree. We do already cover those simple instructions where the same dosage instructions apply every route. Our solution is actually more sympathetic to that scenario than the FHIR models since we allows common instructions for all routes .
THe question is whether there are situations where different dose instructions can be applied to each route without creating multiple orders.I can imagine some use cases for that e.g. Paracetamol Oral / Paracetamol IV - right arm (for someone with lymphoedema). I am also coming across some possible requirements in mental health but so far the professional guidance is somewhat unclear - digging further!!
If we did decide to go down this road it would mean a very significant breaking change to the archetype , so I think we want to be clear that there is a solid and safe reason for doing so, and I that is the case, it might be an opportunity to review the overall design (in terms of supporting Med Statement etc).
This is not my area obviously, but just ruminating on this whole conundrum… is there value in considering alternate routes of the same medications (i.e. the scenario where specialist nurses might decide on the ward) as the same (in IT & modelling terms) as literally alternate medications, which I assume must be dealt with somewhere, i.e. to cover cases of allergy, unavailability (e.g. while travelling) or just ‘finding one that works’ (e.g. mental health)? Then each route version of morphine (say) is actually a separate medication order.
This idea might come undone if these route variations can occur on the same ‘order’, but normally an order = one form of a medication AFAIK. If on the ward morphine can be supplied PO or IV, it implies that it is already generally available in some sense, i.e. each new pack or IV vial is not separately ‘ordered’. I’m guessing a bit here…
Anyway, just an idea…
Hi THomas - that is indeed the de-facto situation i.e the prescriber has to create 2 separate orders for each route/associated dose. In hospital prescribing, the form is normally not defined - just route. The exact form is often left to ward staff/pharmacist to choose
There are clinical safety concerns either way , and the 2 orders approach is often mandated in local guidance.
.If the form or product is prescribed, I would say that should probably be 2 orders but this is where we need good pharmacy colleague advice. Working on it!!
Is there currently a way to associate N ‘alternate’ medications, i.e. ones that are supposed to have the same therapeutic effect? Probably tricky territory I guess, since ACE inhibitors and Beta-blockers are at some level ‘alternatives’ for hypertension, but have totally different physiological mechanisms…