documentation:cdm:cohort

COHORT table

The COHORT table contains records of subjects that satisfy a given set of criteria for a duration of time. The definition of the cohort is contained within the COHORT_DEFINITION table. Cohorts can be constructed of patients (Persons), Providers or Visits.

Field	Required	Type	Description
cohort_definition_id	Yes	integer	A foreign key to a record in the COHORT_DEFINITION table containing relevant Cohort Definition information.
subject_id	Yes	integer	A foreign key to the subject in the cohort. These could be referring to records in the PERSON, PROVIDER, VISIT_OCCURRENCE table.
cohort_start_date	Yes	date	The date when the Cohort Definition criteria for the Person, Provider or Visit first match.
cohort_end_date	Yes	date	The date when the Cohort Definition criteria for the Person, Provider or Visit no longer match or the Cohort membership was terminated.

Conventions

The core of a Cohort is the unifying definition or feature of the Cohort. This is captured in the cohort_definition_id. For example, Cohorts can include patients diagnosed with a specific condition, patients exposed to a particular drug, or Providers who have performed a specific Procedure.
Cohort records must have a Start Date
Cohort records must have an End Date, but may be set to Start Date or could have applied a censored date using the Observation Period Start Date.
Cohort records must contain a Subject Id, which can refer to the Person, Provider, or Visit record. The Cohort Definition will define the type of subject through the subject concept id.