DRUG_EXPOSURE conventions

[Christian_Reich]

@Amit

I am Amit Kumar, a CDISC SDTM Mapping Specialist working in Cytel India. Right now I have got one OMOP CDM Project for ETL creation for an observational study.

We are generating DRUG_EXPOSURE Table in which I have some doubts ,

1. Should we collect all Drug Exposure data captured in raw data like Prior Medication, Study Medication ??
2. Most of Medication History data does not captures date what can we about that.?
   3.What are refill? can we keep them blank?
3. How to generate drug_exposure_id ?

1. Prior medication only if you have the time. Study medication - there is usually no Standard Concept for those, you will have to ask for one in this Forum.
2. Don’t record them. You can only record events if you have the date.
3. You can keep them blank, unless it’s a refill of a prescription.
4. Just count from 1 up. Or use a Fibonacci sequence. Or lottery numbers.

Hope this helps. Again, feel free to contact folks in CDM conversion vendors - #6 by ChrisAndrews.

[Amit (Amitk)]

Hi Christian ,

Thank you so much for responding.

Thank you for providing vendors contact my team will be following it.

Now I addition to above Drug Exposure Table I have some follow up questions regarding the same:

1. With respect to screen shot, Medications history is captured at baseline does not have date field so as per your input we should not include these medication in out Drug Exposure Table.

2.As per OMOP guideline 5.1 Quantity should contain Drug dose captured as in raw data however Effective Drug Dose is its Numerical Equivalent?

3. Route is not getting captured in raw data but we can infer from CRF and Protocol that its “Infusion/Injection” (IV,SC,IM) can we populate Route_concept_id “4112421” and keep route_source_value as blank? Or should we keep both blank as data has not been captured?

Thank you for your support.

Amit

[Christian_Reich]

@Amit:

1. You can record it as an Observation with observation_concept_id=4207283 (“History of drug therapy”), and in the value_as_concept_id you place the RxNorm Ingredient Concept of the respective drug.
2. We are phasing out the effective_drug_dose. Put the amount into the quantity field. The amount can be units (of tablets etc.) or of matter (essentially, milligram). If you have route information, try to convert that to a Dose Form and pick the right RxNorm Drug Form Concept.

[nitishkjha (Nitish Kumar Jha)]

Great…

However if we do so where can we populate other info of Medication history like Dose ,Unit, freq and Route ? In the same observation table ?

Kindly confirm.

[Christian_Reich]

@nitishkjha, @Amit:

Go look in the vocabulary CONCEPT where domain_id=‘Drug’. You will find all the different combinations actually on the market. Which means, you need one concept_id to capture all of the above dimensions. You can also read up here.

[Dymshyts (Dmytry Dymshyts)]

@Christian_Reich
what if we can’t map the drug to exact Clinical Drug or something that has a dosage but the prescription table has a dosage?
My suggestion is to use effective drug dosage in cases when we have Ingredient or Drug Form as a standard concept but have a dosage in prescription table.

[Christian_Reich]

@Dymshyts:

Then put the Ingredient into the drug_concept_id field, and the amount into the quantity field.

[Dymshyts (Dmytry Dymshyts)]

@IYabbarova

Then put the Ingredient into the drug_concept_id field, and the amount into the quantity field.

@Christian_Reich, and Ingredients should have units in drug_strength then?

[Christian_Reich]

@IYabbarova:

Correct. It’s being put in place. Next release.

[IYabbarova (Irina Yabbarova)]

@Christian_Reich
In this case quantity field could contain mixed up information. For example, there can be drug that was mapped to ingredient and there was no other information but qty in source data (let’s say 5 pills), and also the same drug with qty 5, but with dosage info (let’s say 30 mg). At the same time it may be not possible to find RxNorm concept with exact dosage (30 mg) if there is no such concept. What to do in such case?

[Christian_Reich]

@IYabbarova:

If you don’t know the product, and all you are putting in is Ingredient, the quantity is about the compound matter, not some units. So, in your case 30 mg. Make sure you put in the total of the entire exposure. So, if there is a daily dose of 30 mg over a month you need to put in 900 mg.

[Dymshyts (Dmytry Dymshyts)]

@Christian_Reich, all
we have cases similar to this

If you don’t know the product, and all you are putting in is Ingredient, the quantity is about the compound matter, not some units. So, in your case 30 mg. Make sure you put in the total of the entire exposure. So, if there is a daily dose of 30 mg over a month you need to put in 900 mg.

when we can map only to Clinical drug form or Ingredient levels, so in this case units will be defined by the drug_strength table. And we have some cases when the drug dosage can be represented both in MG and Units. In drug_strength we have MG defined, while in our source data there’s Interantional Units ([iU] or [U]), and exact dosage corresponds to the units indeed.
@Alexdavv, can you please provide examples.

[Alexdavv (Alexander Davydov)]

1. nystatin.
   mg is predefined as a unit in DRUG_STRENGTH table. In RxNorm there are no any Clinical Drug Components with mg.

2. bacitracin/ bacitracin zinc.
   mg is predefined as a unit in DRUG_STRENGTH table. In RxNorm there is just only one Clinical Drug Component with mg - bacitracin zinc 0.5 MG/MG which is used just for one single Clinical Drug - bacitracin zinc 0.5 MG/MG / Polymyxin B Sulfate 10 UNT/MG Topical Powder.

3. Penicillin G (almost the same case like bacitracin).

And rather important that in general clinical practise these drugs are measured mostly (sometimes always) in iU. The main question: what units should we use for figures which would be inserted to the DRUG_EXPOSURE.quantity field? If source data contain all the quantities in iU should we convert them to mg and basically how?

[Christian_Reich]

Friends:

Right now, we allow one unit. The ETL would have to convert.

But the vocab team should help by putting out the conversion factors. Let’s figure that out.

[Dymshyts (Dmytry Dymshyts)]

What about the other case:

We have drug administration with the relative units like 20 mg/kg (of patient weight). And we don’t have the weight of the patient to calculate the real dosage.

So we map this to the Clinical Drug Form. And there’s no way to reflect the dosage in drug_exposure table.

[Christian_Reich]

We have drug administration with the relative units like 20 mg/kg (of patient weight). And we don’t have the weight

You really don’t have the dose, then.

But I understand that this sometimes is all you got. And for some drugs the per kg is the important information. Here, I am with @schuemie’s “let’s just add a field”. This is a piece of information we cannot store right now without re-defining the content of other fields.

@Dymshyts: Can you put a proposal into the CDM Github? Something like “dose_per_kg” with allowable values NULL (usual) and Y.

[Mark_Danese]

You might consider being more flexible on the units. The denominator can be weight, body surface area, and maybe 1 or 2 other things I can’t recall at the moment.

[Christian_Reich]

@Mark_Danese:

True. In that case we could add a “alternative_denominator_unit_concept_id”.

[Chris_Knoll]

True. In that case we could add a “alternative_denominator_unit_concept_id”.

That column name would not fit in an oracle database.

[Christian_Reich]

Urgh. Forget the denominator then. alternative_unit_concept_id?