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EU drugs to RxNorm, call for help

OHDSI in Europe
#1

Hi OHDSI Community,

we’ve worked on a mapping of our national drug codes (Austria, PZN) to RxNorm. To our knowledge, all previous mapping efforts in Austria use the official PZN->ATC mapping to get to RxNorm on ingredient level only. For our current OMOP project we tried to use more available information (strength, dose form, translations, etc.) to automatically derive a more precise mapping. At first glance this approach seems to work reasonably well, but we have no means to validate our approach.

One idea for a validation would be to exploit existing PZN->EU approval number mappings available to us, and compare them to other EU->RxNorm mappings available somewhere in Europe. We have these approval numbers e.g. in the form “EU/1/04/276/001”.

My hope is to find such an EU->RxNorm mapping through this community or any other helpful leads. I very much appreciate this community and any help from you.

Thank you,
Florian

#2

Hello Florian,

OMOP CDM uses synthetic vocabulary called RxNorm Extension to accomodate international (as in: everything outside of RxNorm’s homefield of US) drugs. To do that, we split every source concept into a set of defining attributes (dosage, ingredients, dose form, brand name etc.), and build extension of existing RxNorm hierarchy to accomodate both the source concept and all of it’s virtual parents (e.g. dosage and ingredient combined, but without dosage data), where match to existing concepts is impossible. And beyond just ingredient level, there are a lot of international variation of brand names relation to ingredients, common dosages and accepted dose forms.

It should be technically possible with our methods to limit matching just to existing concepts, and to only “real” RxNorm vocabulary for that purpose. What is the source structure of PZN? Does it provide attributes like ingredients for drug concepts explicitly, in separate lookup tables?

1 Like
#3

Hi Eduard,

thanks for your reply, and sorry for not explicitly stating that we actually were doing the mapping to RxNorm (were possible) and RxNorm Extension (were needed). Our source vocabulary has ingredients, strength, dose form and additional information (e.g. package form, non-active ingredients, sometimes brand names, ATC codes, EU registration numbers). This additional information is not present for all drugs and present in german language.

So, I’m really looking for existing mappings from drugs with EU registration numbers (can be from any european country I suppose) to RxNorm/RxE.

#4

I am very certain that we do not store EU approval numbers anywhere, so you would have to find lookups from national vocabularies to EU approval numbers elsewhere. However, OMOP has multiple European national drug classification systems currently mapped to RxNorm/RxE, with varying level of current support. If you have EU number lookup for each of these classification systems, you could utilize the existing mapping.

Among those are BDPM (France), GGR (Belgium) and dm+d (UK, if it may still count), and probably more others. To view all existing Drug vocabularies, you can look at VOCAB filters here, or take a look at all available vocabularies here(this page requires free registration).

That all being said, there is a documented semi-automated process to obtain mappings from source to RxN/E directly, by mapping all their “building blocks” like ingredients and dose forms to corresponding RxNorm/RxE atoms. That is the OMOP way, and how mappings from BDPM and like are built in the first place. If your end goal is to have PZN mapped, that way may even be easier, depending on availability of EU numbers lookups. There is this documentation page, that describes the process, but I’m not sure if it is the most recent one. Asking @Alexdavv and @zhuk.

#5

Thank you so much, I think this was the hint I needed. I found downloadable files for BDPM that contain EU registration numbers and with that I should be able to achieve my goals.

I’m aware of the semi-automated process, and I was more or less adopting this process in my mapping efforts. Thanks for this reminder.

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#6

Dear @floriankatsch,

We are doing a similar project now, mapping our Hungarian drug codes, and we also thought of using the EU registration number. (Thanks, @MaximMoinat, for pointing me to this thread.)
Could you help us by providing the source where you found the BDPM downloadable files with the EU registration number? We would also use this process to create an EU registration number - RxNorm and RxE mapping. Or did you already create this mapping file? If yes, and it is not too much to ask, we would happily reuse it. :slight_smile:

Thank you,
Agota

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#8

Edit: corrected the link

Hi @Agota_Meszaros,

I’m currently using the “Specialties file” and “Presentation file” from https://base-donnees-publique.medicaments.gouv.fr/telechargement.php.
CIP7 code contained there are also used to identify drug products in OMOPs BDPM vocabulary, the Specialty Identifier Code (CIS) is used to identify drugs and has EU registration numbers assigned. However, the EU registration numbers are coarser than the one I have available in my source data, e.g. “EU/x/xx/xxx”, so multiple drugs get effectively assigned to a single EU registration number. We therefore use the common ancestor of all RxNorm drugs assigned in this way to a EU number for our validation.

We currently prepare the manuscript on our results, feel free to reach out for further information.

Best, Florian

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