Case-control study

In a case-control study it is investigated if persons with a certain disease (so-called cases) have been exposed more or less frequently than comparable persons without this disease (so-called controls). Frequently a certain disease is examined in more detail within the scope of a cohort study. All persons with this disease (so-called cases) are selected from the cohort as well as an accidental part of persons from the cohort without this disease (so-called controls) are selected. Subsequently further interrogations or polls are carried out for this subgroup. This type of study is referred to as nested case-control study since the case-control study is nested into a cohort study.