Drug Exposure

The Drug Exposure domain captures records about the utilisation of a drug when ingested or otherwise introduced into the body. A drug is a biochemical substance formulated in such a way that when administered to a person it will exert a certain physiological effect. Drugs include prescription and over-the-counter medicines, vaccines, and large-molecule biologic therapies. Radiological devices ingested or applied locally do not count as drugs.

Drug Exposure is inferred from clinical events associated with orders, prescriptions written, pharmacy dispensing, procedural administrations, and other patient-reported information, for example:

• The “Prescription” section of an EHR captures prescriptions written by physicians or from electronic ordering systems.
• The “Medication list” section of an EHR for both non-prescription products and medications prescribed by other providers.
• Prescriptions fulfilled by pharmacies.
• Drugs administered as part of a procedure, such as chemotherapy or vaccines.

Field	Required	Type	FK Table	Description
drug_exposure_id	Yes	bigint		A system-generated unique identifier for each Drug utilisation event.
person_id	Yes	bigint	PERSON	A foreign key identifier to the Person who is subjected to the Drug. The demographic details of that Person are stored in the PERSON table.
drug_concept_id	Yes	bigint	CONCEPT	A foreign key that refers to a Standard Concept identifier in the Standardized Vocabularies for the Drug concept.
drug_exposure_start_date	Yes	date		The UTC start date for the current instance of Drug utilisation.
drug_exposure_start_datetime	No	datetime		The UTC start date and time for the current instance of Drug utilisation.
drug_exposure_end_date	No	date		The UTC end date for the current instance of Drug utilisation. This is populated in the event that a datetime is not available (e.g. for home administrations).
drug_exposure_end_datetime	No	datetime		The UTC end date and time for the current instance of Drug utilisation. It is NULL if the administration is not complete.
verbatim_end_date	No	date		Not used.
drug_type_concept_id	Yes	bigint	CONCEPT	A foreign key to the predefined Concept identifier of the “Type Concept” domain in the Standardized Vocabularies reflecting the type of Drug Exposure recorded.
stop_reason	No	varchar(20)		Not used.
refills	No	integer		Not used.
quantity	Yes	numeric/float
days_supply	No	integer		Not used.
sig	No	text		Not used.
route_concept_id	No	bigint	CONCEPT	A foreign key to a predefined concept in the Standardized Vocabularies reflecting the route of administration.
lot_number	No	varchar(50)		Not used.
provider_id	No	bigint	PROVIDER	Not used.
visit_occurrence_id	No	bigint	VISIT_OCCURRENCE	A foreign key to the Visit Occurrence during which the Drug Exposure was initiated.
visit_detail_id	No	bigint	VISIT_DETAIL	A foreign key to the Visit Detail during which the Drug Exposure was initiated.
drug_source_value	No	varchar(50)		Not used.
drug_source_concept_id	No	bigint	CONCEPT	Not used.
route_source_value	No	varchar(50)		Not used.
dose_unit_source_value	No	varchar(50)		Not used.
last_updated_datetime	Yes	datetime		Initially this is the time the row was written to OMOP. If the row is subsequently updated, it then becomes the most recent update time.
deleted_datetime	No	datetime		NULL initially. Set to the time when the row was marked for deletion. A value in this column sent to the central data source will result in this row being deleted (by person_id ) from the combined dataset. Deletions only need to be sent once.

Conventions

• Valid Concepts for the drug_concept_id field belong to the “Drug” domain. Most Concepts in the Drug domain are based on RxNorm, but some may come from other sources (like dm+d). Concepts are members of the Clinical Drug or Pack, Branded Drug or Pack, Drug Component or Ingredient classes.
• A Drug Type is assigned to each Drug Exposure to track from what source the information was drawn or inferred from. The valid domain_id for these Concepts is “Type Concept”.
• The route_concept_id refers to a Standard Concept of the “Route” domain. Note: Route information can also be inferred from the Drug product itself by determining the Drug Form of the Concept, creating some partial overlap of the same type of information. However, the route_concept_id could resolve ambiguities of how a certain Drug Form is actually applied. For example, a “Solution” could be used orally or parenterally, and this field will make such determination.
• If possible, the Visit in which the drug was prescribed or delivered is recorded in the visit_occurrence_id field through a reference to the VISIT_OCCURRENCE table.