If we will drop the prescribed quantity and will calculate the actual quantity based on discontinue date: drug_exposure.quantity = (discontinue date - start_date + 1) * daily dose - it will contradict the definition of quantity field from OMOP CDM:
The quantity of drug as recorded in the original prescription or dispensing record.
- Would it be OK to populate drug_exposure.quantity with the value not from original prescription?
And one more question on discontinued/stopped medications 
- If I understood correctly from GitHub item End of a Drug Exposure · Issue #71 · OHDSI/CommonDataModel · GitHub : in the case of stopped/discontinued medications it is ok to have days_supply which doesn’t correlate with drug_exposure_end_date. As days_supply populated with the prescribed value may allow to analyse the prescribed duration with the real duration? Or should we recalculate days_supply based on discontinue date?