Improving Your Critical Appraisal Skills #2

The Cohort Study

Cohort studies are observational studies. They are natural experiments that might be examined prospectively or retrospectively. Classically, cohort studies are used to assess the prognosis of a group of patients. This is (mostly) how the Users’ Guides article examines them. A cohort study tells you about the risk of a certain group of people or patients developing an outcome. Cohort studies can also compare the prognosis of two groups. For example, what are the rates of stroke in patients with chronic atrial fibrillation and in similar people without Afib?