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THIS IS OUTDATED. All documentation is now on the github wiki. Please refer there or to the CDM working group for more information

The COHORT_DEFINITION table contains records defining a Cohort derived from the data through the associated description and syntax and upon instantiation (execution of the algorithm) placed into the COHORT table. Cohorts are a set of subjects that satisfy a given combination of inclusion criteria for a duration of time. The COHORT_DEFINITION table provides a standardized structure for maintaining the rules governing the inclusion of a subject into a cohort, and can store operational programming code to instantiate the cohort within the OMOP Common Data Model.

cohort_definition_idYesintegerA unique identifier for each Cohort.
cohort_definition_nameYesvarchar(255)A short description of the Cohort.
cohort_definition_descriptionNoCLOBA complete description of the Cohort definition
definition_type_concept_idYesintegerType defining what kind of Cohort Definition the record represents and how the syntax may be executed
cohort_definition_syntaxNoCLOBSyntax or code to operationalize the Cohort definition
subject_concept_idYesintegerA foreign key to the Concept to which defines the domain of subjects that are members of the cohort (e.g., Person, Provider, Visit).
cohort_instantiation_dateNoDateA date to indicate when the Cohort was instantiated in the COHORT table


  • The cohort_definition_syntax does not prescribe any specific syntax or programming language. Typically, it would be any flavor SQL, a cohort definition language, or a free-text description of the algorithm.
  • The subject_concept_id determines what the individual subjects or entities of the Cohort consists of. In most cases, that would be a Person (patient). But cohorts could also be constructed for Providers, Visits or any other Domain. Note that the Domain is not codified using the alphanumerical domain_id like in the CONCEPT table. Instead, the corresponding Concept is used. The Concepts for each domain can be obtained from the DOMAIN table in the domain_concept_id.
documentation/cdm/cohort_definition.txt · Last modified: 2017/09/25 14:59 by clairblacketer