ABSTRACT
The aim of a case-control study is to assess whether historical exposure to one or more risk factors in people who have a disease is comparable to that in people who do not have the disease. Case-control studies are generally easier and quicker to complete than cohort studies. In a case-control study, a number of cases are assembled, consisting of subjects who already have a known disease. In addition, a number of controls are gathered who do not have the disease, but who are similar in other respects. Both groups are then investigated in order to ascertain whether they were exposed to a particular risk factor. In a case-control study, data are collected by surveying subjects or collecting information from medical records. The odds ratio should normally be used in a case-control study. The Chi-squared test can also be employed. However, care needs to be taken when interpreting results, as a strong association does not necessarily indicate a causal relationship.
