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HCPCS > RxNorm one-to-many mapping

As @Christian_Reich pointed out in an earlier discussion, some HCPCS codes map to multiple RxNorm codes. Specifically, when there’s no way to infer the SCD RxNorm code, we get a one-to-many map to every ingredient. This only seems to be the case for a handful of HCPCS codes:

select c.concept_id, c.concept_code, c.concept_name, count(c2.concept_id)
from concept c
join concept_relationship cr on c.concept_id = cr.concept_id_1 and c.vocabulary_id = 'HCPCS'
join concept c2 on c2.concept_id = cr.concept_id_2 and c2.vocabulary_id = 'RxNorm'
group by c.concept_id, c.concept_code, c.concept_name
having count(c2.concept_id) > 1

but nonetheless, I’m curious how folks are handling it. We’re currently inserting multiple rows into drug_exposure, each with a different drug_exposure_id. Maybe later on down the line, we can put something into fact_relationship indicating that all four drug_exposure_ids come from the same product. Are others doing the same thing? Does this approach seem rational?

@esholle:

Well, there are folks pushing for adding the MIN class back into RxNorm, which currently are taken out. It has fixed ingredient combos. Reason we are considering this is that it is easier to do that and add the combo-Clinical Drug Components, that trying to keep it out.

Will keep you posted. We are having a lot of open heart surgeries on the vocabulary going on right now. Scary. But good. Love having the community pushing things.

t