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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.

cohort_definition_idYesintegerA foreign key to a record in the COHORT_DEFINITION table containing relevant Cohort Definition information.
subject_idYesintegerA foreign key to the subject in the cohort. These could be referring to records in the PERSON, PROVIDER, VISIT_OCCURRENCE table.
cohort_start_dateYesdateThe date when the Cohort Definition criteria for the Person, Provider or Visit first match.
cohort_end_dateYesdateThe date when the Cohort Definition criteria for the Person, Provider or Visit no longer match or the Cohort membership was terminated.


  • 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.
documentation/cdm/cohort.txt · Last modified: 2014/12/05 21:07 by cgreich