We are preparing our source data for mapping to the OMOP CDM. Our data originate from a prescribed drug register that contains all pharmacy-dispensed medications for all individuals in the source population over time. For these individuals we also have information on inpatient and outpatient care visits from a patient register. We are unsure whether the records from the prescribed drug register should be inserted into the visit_occurrence table as pharmacy visits. I.e, for analyses involving drug exposures, is it necessary for these pharmacy records to be linked to the visit_occurrence table via the visit_occurrence_id, or would it be sufficient to map these records to drug specific tables only? Thank you!
It is not required to link a drug exposure to a (pharmacy) visit. Often drug exposures are only linked to visit if given as part of a inpatient/outpatient visit. Do you have an analytical use case for creating visits for just drug dispensing?
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Thanks for the prompt and clear response. We don’t have an analytical use case, as the drug exposures aren’t linked to inpatient or outpatient visits.
There is no official position from the community on this. My recommendation is to use a person visit centric approach, ie no event record should exist without an entry in visit table. This is the recommendation of the HEVA workgroup.
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OHDSI’s “official position” is a Visit Occurrence record is NOT required for any clinical event, including records in the Drug Exposure table. You can find all rules and requirements for OMOP CDM v5.4 here.
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