Glossary · Methodology
Cohort study
In short
A cohort study follows a group of people for years and compares who, with which characteristics or habits, later develops which disease. It is a strong form of observational study, but does not replace an experiment.
Prospective means the data are collected before the outcomes are known. This protects against recall errors, which arise when people who are already ill are asked about their habits in retrospect. A large example is the UK Biobank with around half a million participants.
The result is usually given as a hazard ratio: how much more or less often an event occurs in one group than in another. Confounders are adjusted for as far as they were measured. What was not measured stays in the result.
A cohort shows who gets ill — not why.
Where this comes up in the fact checks
- Sauna & cold – A cohort study counts who goes to the sauna how often and who has died years later — it shows an association, not a cause.
- ApoB test – In the UK Biobank, with all blood lipids considered together, only ApoB was associated with heart attacks.
- Coronary calcium score – A strong risk marker from large cohorts; whether screening prolongs life is not shown by this.
Sources
Related terms: Observational study · Hazard ratio · Mendelian randomization
Information only, not medical advice. The BK-Score is a subjective assessment according to disclosed rules – not a scientific evaluation. Scoring rules