What is a case-control study in medical research?

What is a case-control study in medical research?

Markus MacGill

A case-control study is a type of medical research investigation often used to help determine the cause of a disease, particularly when investigating a disease outbreak or a rare condition.

If public health scientists want a relatively quick and easy way to find clues about the cause of, for example, a new disease outbreak, they can compare two groups of people:

• Those who already have the disease – ‘cases’
• Similar people who have not been affected – ‘controls.’

A case-control study is retrospective – the researchers look back at data collected in the past, enabling them to test whether a particular outcome can be linked back to a suspected risk factor. To test for specific causes, the scientists need to formulate a hypothesis about what they think could be behind the outbreak or disease. They then compare how often the group of cases had been exposed to the suspected cause (risk factor), versus how often the controls had been exposed. If the risk factor has a greater prevalence among the cases, then this is some evidence to suggest that it is a cause of the disease.Risk factors could be uncovered by researchers studying the medical and lifestyle histories of the people in each group. A pattern may emerge that links the condition under investigation to certain factors.Case-control research is a central tool used by epidemiologists, who look into the factors that affect the health and illness of populations.Just one risk factor could be investigated for a particular disease outcome. A good example of this is to analyze how many people with lung cancer, versus how many without, have a history of smoking.

A case control study .pdf