Difference Between Cohort and Case-Control Study

Key Difference  – Cohort vs Case-Control Study
 

Cohort and case-control study are two of the designs used in research between which some difference can be identified. A researcher who is about to conduct a study on a specific field usually has research objectives and questions. Based on these, the researcher chooses a research design that will be most appropriate for the study. A cohort study is a research design where the researcher studies a group of people, also known as a cohort, for a longer period of time. On the other hand, a case-control study is a research design used by researchers where the research begins with an outcome to comprehend the cause. One key difference between cohort and case-control study is that the cohort study is prospective while the case-control study is retrospective. Through this article let us further examine the differences between a cohort study and a case-control study.

What is a Cohort Study?

A cohort refers to a large group of people who share similar characteristics. This can be an experience that the individuals shared such as exposure to a traumatic event or even a particular year in which the individuals were born, graduated, etc. For example, people born in 1991 belong to a single cohort since they share a specific characteristic with others (year of birth).

Cohort studies are used in various disciplines ranging from social sciences to medicine. In all these disciplines, a cohort is studied with the intention of gaining a unique experience that the individuals underwent. Simply, cohort study relates the life histories of people. In medical disciplines, a cohort study allows the researcher to comprehend a potential cause of disease.

Let us comprehend this through an example. In a cohort study, a researcher begins to study a particular group (such as women) who share a common characteristic. The individuals in the cohort may or may not develop the diseases in question. The researcher then identifies those who have the disease and those who do not and study both groups with the intention of identifying the risk factors.  The specialty in cohort studies is that they can be longitudinal studies that go on for months or even years. Some cohort studies last for decades. In such an atmosphere, it is vital that the researcher maintains a good rapport with the cohort. Now that we have a fair understanding of a cohort study let us move on to the next section.

Difference Between Cohort and Case-Control Study

What is a Case-Control Study?

A case-control study is a research design used by researchers where the research begins with an outcome in order to comprehend the cause. Hence, this is a retrospective study. These studies are mostly used in a range of disciplines.  In a case-control study, there are two groups of people. One who has a condition and the other that does not. Other than these control factors, other factors are similar in both groups. Then the researcher tries to identify the condition that was visible prevalent for the first group and not the second. However, a main concern in case-control studies is that they cannot predict causation, although they can present possible risk factors.

Let us comprehend a case-control study through an example. Imagine a researcher conducts a study on diabetes. The researcher first identified people from a particular region and put them into two groups as the cases and controls. Cases refer to the people who have diabetes and controls refer to the people who do not. Then he conducts a research where he questions the individuals of the two groups to identify possible risk factors.

As you can observe there is a clear difference between a cohort study and a case-control study. Now let us summarizes the difference as follows.

Cohort vs Case-Control Study

What is the Difference Between Cohort and Case-Control Study?

Definitions of Cohort and Case-Control Study

Cohort Study: A cohort study is a research design where the researcher studies a group of people also known as a cohort for a longer period of time.

Case-Control Study: A case-control study is a research design used by researchers where the research begins with an outcome to comprehend the cause.

Characteristics of Cohort and Case-Control Study

Observational study

Cohort Study: A cohort study is an observational study.

Case-Control Study: A case-control study is also an observational study.

Nature

Cohort Study: This study is prospective.

Case-Control Study: This is retrospective.

Grouping

Cohort Study: The researcher studies the entire cohort without grouping as controls and cases.

Case-Control Study: Controls and cases are chosen at the beginning.

 

Image Courtesy:
1. “Women logo” by Unknown – Women’s Health Initiative [Public Domain] via Wikimedia Commons
2. “ExplainingCaseControlSJW“. [CC BY-SA 3.0] via Wikipedia