cohort
Meaning of cohort: In research, a cohort is a defined group of people sharing a characteristic or experience, followed over time to study health outcomes.
Definition of cohort
A cohort is a group of people who share a defined characteristic or experience, such as a birth year, an occupation, or exposure to a particular medication, and who are studied together over time. The term is used broadly in epidemiology and clinical research whenever investigators want to observe how a shared trait relates to later health outcomes.
In a cohort study, researchers follow a defined group forward in time, comparing outcomes between those with and without a particular exposure or characteristic, to identify factors that increase or decrease the likelihood of developing a condition. Some cohort studies instead look backward, reconstructing exposure and outcome information from existing records.
Because a cohort study observes people rather than assigning them to a treatment, it can suggest an association between an exposure and an outcome but generally cannot establish that the exposure caused the outcome as directly as a controlled trial can.
Used in a sentence
The research team assembled a cohort of patients diagnosed within the same year to track long term outcomes.
Good to know
A cohort study is often confused with a clinical trial, but a cohort study observes existing groups rather than randomly assigning an intervention, which limits its ability to establish cause and effect.