Cohort Definitions

A cohort is defined using one or more Concept Sets. For example, one Concept Set could contain clinical diagnostics codes while another could contain administered drugs.

Cohorts are created using Cohort Definitions that define entry, inclusion and exit criteria for Concept Sets:

• Cohort Entry Events (mandatory): enter people into the cohort by defining medical event codes using Add Initial events.

• Inclusion Criteria (optional): include (or exclude) people from the cohort by defining medical event codes using New inclusion criteria. By default, no criteria are defined.

• Cohort Exit (optional): remove people from the cohort. By default, people will be part of the cohort until the time of death or the end of the follow-up period (end of continuous observation).

Different cohort definition rules are needed for different Atlas Domains. FinnGen uses the following Atlas Domains and tables for medical event codes:

Domain	Cohort definition rule	Table
Condition	Add Condition Occurrence	CONDITION_OCCURRENCE
Procedure	Add Procedure Occurrence	PROCEDURE_OCCURRENCE
Drug	Add Drug Exposure	DRUG_EXPOSURE
Measurement	Add Measurement	MEASUREMENT
Observation	Add Observation	OBSERVATION
Condition	Add Death	DEATH

Topics in the section

• Using the Death register in Atlas

• Filtering by clinical registries in Atlas

• Filtering by demographic criteria in Atlas

• Defining exit rules for a cohort in rules

• Selecting the correct bo in Atlas for events and medical codes

Upcoming topics

Complex cohorts with nested criteria

• How to define cohort with disease onset in a time range (NO INSTRUCTIONS FOR THIS YET)

• How to define cohort using medication intervals (NO INSTRUCTIONS FOR THIS YET)

• How to define cohort with seasonal rules (NO INSTRUCTIONS FOR THIS YET)

• How to import a standard cohort from OHDSI phenotype library (NO INSTRUCTIONS FOR THIS YET)