medicationCodeableConcept returns ingredients instead of medications

[Richard Hensel]

Can you explain how the mapping is done between the medication in the EMR and the medicationCodeableConcept in the FHIR MedicationOrder? Is each facility responsible for mapping its own formulary to the correct RxNorm rxcui? Or is the mapping done by the drug database vender?

Specifically, I am seeing RxNorm ingredients (IN) being referenced in the medicationCodeableConcept where there should be RxNorm SCD, SBD, etc.

For example, patient 'Amber Read' (in the sandbox) has this medication:

"medicationCodeableConcept": {

                  "coding": [

                     {

                        "system": "http://www.nlm.nih.gov/research/umls/rxnorm",

                        "code": "29046",

                        "display": "Lisinopril",

                        "userSelected": false

                     }

                  ],

                  "text": "lisinopril"

               },

               "dosageInstruction": [

                  {

                     "text": "5 mg, 1 tabs, Oral, Daily",

The rxcui '29046' in RxNorm points to:

rxcui sab                 tty code str

29046 RXNORM IN 29046 Lisinopril

which is an ingredient, not a medication.

The dosage instruction clearly shows that it is a 5 mg tablet, so the correct rxcui should be:

rxcui sab                 tty         code str

311354 RXNORM SCD 311354 Lisinopril 5 MG Oral Tablet

Since our FHIR application needs to know the exact medication ordered, these mis-mappings are very problematic. We've seen this issue in CCDs for years.

(Often, facilities will create their own compounds - especially for children - and use ingredients as the rxcui but in cases like this, its simply a wrong mapping).

So my question is, who is ultimately responsible for creating these mappings and is it possible to reach out to them to correct?

Thanks for any information you can provide.

 

[Richard Hensel]

Just to follow up:

From looking at our client's formularies, I can see that there are often several mappings, which may include SBD, SCD, IN, PIN - all of which are valid for the medication. Is it possible that the EMR code that extracts the RxNorm rxcui is just pulling the first entry and not actually filtering for the best possible result?

[Michele Mottini]

Isn't this user-entered data...and as such wouldn't always be possible that a user picks only the ingredient instead than the complete description?

  - Michele

  CareEvolution Inc

[Richard Hensel]

Do you mean that in their formulary, the facility has only mapped an RxNorm ingredient to that medication?

That's why I'm wondering if it is, in fact, each facility that does its own mapping or is it the drug database vendor (i.e. First Databank)?

[Jenni Syed (Cerner)]

Hi Richard,

Michele is correct - what is specifically chosen/ordered determines how this mapping is exposed. What is ordered often varies between workflows. For example, in inpatient settings, only the ingredients are chosen. Prescriptions, however, are often ordered with more specific strength and information.

The system does not attempt to look at the dosage to choose a more specific coding - these are essentially post-coordinated codes from that perspective in many workflows (the dose and coding are chosen separately rather than entirely contained within the coding).

~ Jenni

[Richard Hensel]

Jenni (and Michele) - thanks to your explanations, now I understand. That question has been bugging me for a long time.