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Adding Defined Daily Dose (DDD) from WHO


(Ilya Katz) #1

Is there a way to access defined daily dose (DDD) information for drugs, as created by the WHO (https://www.whocc.no/ddd/definition_and_general_considera/) within the OMOP common data model. The WHO connects ATC codes to this index so it would presumably be a relatively simple mapping, but I haven’t seen DDD among the vocabularies that are currently being updated.


How to update vocabulary regularly for our data
(Anna Ostropolets) #2

Daily dose is a part of ATC codes, so it (ideally) would be incorporated into the mapping from ATC to RxNorm so that ATC codes with specific daily dosages will be mapped to corresponding RxNorms with the appropriate dosages. Still work in progress though, see here:ATC Working Group: Meeting Agenda and Minutes


(Dmytry Dymshyts) #3

Wait, what if someone uses 2 or 4 or 1/2 pills a day? How do you relate daily dosage to the drug product dosage?


(Mandar) #4

@Dymshyts I noticed that this thread is about a year old. Can we now get dosing information from the OMOP drug_exposure table?


(Anna Ostropolets) #5

There is currently no way to get this information from the vocabulary, mainly because ATC specifies daily dosage and not the strength per a unit of drug. So, say, 2 grams of aspirin can correspond to one tablet 2g, two tablets 1 g, 4 tablets 500 mg and so on.
We don’t have a good solution to this issue, so any suggestions would be greatly appreciated.


(Mandar) #6

@aostropolets Anna, looks like in the current drug_exposure table we can get information regarding the drug (e.g., OMOP ID: 19019273, naproxen 500 MG Oral Tablet), quantity (e.g., 30), and days (e.g., 10).

Curious on the semantics of quantity, does this mean 30 tablets or 30 strips each containing 10 tablets?

Can we use this data to estimate?

  1. Daily dosage
  2. Dosage per dose(e.g., depending on 2 or 3 times per day even assuming uniform dosage per dose)

(Don Torok) #7

The code to create dose era’s has to determine the daily does. See https://github.com/OHDSI/Era-Constructor/blob/master/v5/PostgreSQL/postgres_v5_drug_era_without_stockpile.sql


(Anna Ostropolets) #8

Depends on the ETL, but generally it is 30 tablets. If a drug is in a form of box, e.g. Aspirin 500 MG Tablet [Box of 30], the quantity would represent the number of boxes.

You can use drug_exposure data to estimate the daily dosage, but I don’t see how it can be linked to vocabularies. CDM tables populated by ETL specialists from the source data and pre-defined OMOP Vocabs live separate lives.


(Andrew S. Kanter, MD MPH FACMI FAMIA) #9

I would think that most clinical systems include either a SIG for prescribing or a quantity for dispensing. I don’t think either would normally include packaging (although a pharmacy inventory system might). As a clinician I usually would see something like: Naproxen 500 mg (oral tablet), 1 by mouth four times per day… so drug + strength + form (coded), dose quantity, frequency, duration plus possible dispensed quantity (4x30d=120 pills). In some EMRs, this is captured as a coded drug only with separate fields for dose (strength x quantity), route, frequency, duration, etc. Naproxen 500 mg by mouth four times a day (Naproxen 500 mg PO QID)


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