Cohort Definition
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.
More details about cohorts in The Book of OHDSI: https://ohdsi.github.io/TheBookOfOhdsi/Cohorts.html#Cohorts
Field | Required | Type | FK Table | Description |
---|---|---|---|---|
cohort_definition_id | Yes | bigint | A unique identifier for each Cohort. | |
cohort_definition_name | Yes | varchar(255) | A short description of the Cohort. | |
cohort_definition_description | No | text | A complete description of the Cohort definition | |
definition_type_concept_id | Yes | bigint | CONCEPT | Type defining what kind of Cohort Definition the record represents and how the syntax may be executed |
cohort_definition_syntax | No | text | Syntax or code to operationalize the Cohort definition | |
subject_concept_id | Yes | bigint | CONCEPT | A foreign key to the Concept defining the domain of subjects that are members of the cohort (e.g., Person, Provider, Visit). |
cohort_initiation_date | No | Date | A date to indicate when the Cohort was initiated in the Cohort table |
Conventions
- 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). However, cohorts could also be constructed for Providers, Visits or any other Domain.