Overview on cohort study design

Published on February 28, 2023   44 min

A selection of talks on Methods

Hello everyone, this is Dr. Rana Ismail. I'm an adjunct assistant professor at Michigan State University, College of Osteopathic Medicine in the USA. Today, we're going to cover the overview of cohort study design.
In this lecture, we are going to cover one of the main observational designs, the cohort study. We're going to start by defining what a cohort means; how we do a cohort selection; the two types of cohort studies; what we use cohort studies for; the pros and cons of retrospective study design; the things to consider when choosing a cohort study design; the statistics used in cohort studies; and we're going to go over some working examples. Finally, we will cover the proper interpretation of relative risk, which is the hallmark statistic of cohort studies.
As you can see here, we have a Roman legion which here represents a cohort or a group of people, so it's a sample of the population, a legion from the army. And this is exactly what cohort means, a group that you follow over time.
What's a cohort? A cohort is a group of individuals or a well-defined population subset with a common or shared feature that is followed longitudinally over time. The cohort is a representative sample of the population, and there are two ways you can follow the cohort. Forward into the future, that is prospective cohort, or follow the cohort to the past- that is a retrospective cohort. These two designs, prospective and retrospective, prompt the researcher to collect data on predictors of outcomes. In the forward, prospective manner - before the outcome occurs and you measure the outcome over time - or in a retrospective manner, when the outcome has occurred and the researcher collects data on the detector valuables in retrospect. Examples of cohorts, for example, you take a group of healthcare professionals, a group of individuals with certain conditions such as for example diabetes. Or, you take a group of people with certain characteristics, let's say they're Millennials that warn between a certain time period or a group of people who are smokers or anything, they have some exposure.