We use RxNorm as the standard for drugs, and RxNorm encodes drug strength in its drug identifiers (e.g. concept ID 19041845 stands for 'Carbocysteine 250 MG Oral Tablet'). However, especially outside of the US there are many drugs that are prescribed in a different strength than what is in RxNorm. For example, in Japan clarithromycin is most often prescribed as 200mg tablets, and there is no corresponding code in RxNorm (only 50mg ,250mg, 500mg, 1000mg tablets). As a consequence, we are forced to map to the ingredient level, and lose the strength information even though it is available and structured in the source data. In general, this makes the idea of deriving a dose_era table pretty useless: only part of the prescriptions of an ingredient will have associated strength as encoded in RxNorm clinical (or branded) drugs, but for the most part the information is lost, and the loss is non-random.
To fix this, I suggest we copy some of the fields of the drug_strength table to the drug_exposure table:
And we'll probably also need to add
- dose_form_concept_id (indicating whether its a tablet, solution, cream, etc.)
This way, if we're unable to map to a clinical drug, we can map to the ingredient and use these fields to keep all the relevant information. For drugs with multiple ingredients, we could use one row per ingredient.
@Christian_Reich: what do you think? Something to add to CDM v5.1?