Question: Past Medications in FHIR

Dec 3, 2013

Question: 

When the application I work with receives medication information for a particular patient from a GP clinical system we differentiate between current medication and past medication. I’m not aware of a published definition of ‘current’ and ‘past’ in this context and I’m sure it’s not the job of FHIR resources to provide one but is it the intention that the MedicationStatement resource be used to record medicines that the patient is currently taking (or has available to take if needed) – i.e. ‘current medicines’, as well as those that have been stopped and are no longer exerting a physiological effect on the body – i.e. ‘past medicines’?

Answer:

Well, this is not a straight forward answer. There are some complicating factors:

  • Systems (and clinicians) vary wildly whether “medication” refers to prescribed and/or dispensed medications, records of administration, or just claimed belief on the part of the patient and/or the clinician that the patient routinely takes, or expects to take (or something) a particular medication. In FHIR, there are specific resources for all 4 of those things. I think that medication statement is the right one (and it’s intended to be the right one), but the context of the source system cannot be ignored
  • There’s a real lack of clarity about “past” - what makes a medication “past?” This is both a theoretical question, and a practical one.
  • On the theory side, simply because a medication is not longer being administered it cannot be considered to be past until all physiological consequences are finished. This can be a long time (e.g. Amiodarone)
  • On the practical side, how do you know? You have a prescription, it’s expired, so you automatically call it past? Tricky stuff

Having said that, the basic answer is that in FHIR, the anticipation is that there will be lists (a list resource), a (probably curated) list of current medications, and a list of past medications. You can tell by which list a medication statement is in whether it’s considered past or current.

I don’t find that answer entirely convincing, and we’ll be trying to get a clearer picture of this during the trial use period, but I suspect that this won’t be possible- the sheer variation in approach to tracking medication usage continues to astound me. In the end, what you do will have to be driven by local policy or business practice.