3. Types of epidemiological studies

3.2 Analytic studies

3.2.1 Observational studies

Figure 5: The principle of a case-control study

Figure 5: The principle of a case-control study

A. Case-control studies

An observational study is conducted on 2 groups :

  • The group with the disease: the cases

  • The group without the disease: the controls

This type of study compares the proportion of people in the 2 groups who have been exposed to an environmental factor, or they have an element associated with their lifestyle (e.g. consumption of alcohol, smoking, etc.), with genetics, etc.

For example:

  • the link between lung cancer and smoking

  • the link between oral contraceptives and the risk for thrombosis