Case-control (retrospective) studies are one of the basic types of observational studies in the medical market – similar to cohort studies, they serve to quantify the relationship between exposure (the causative agent) and its effect (disease phenomenon).
The idea of the research process is based upon a comparative analysis of a group of people suffering from a particular disease (research group) and a group of healthy people (control group) – within the scope of the analysis, you begin from the endpoint (moment of exposure), and the risk of exposure is assessed retroactively.
Use of case-control studies
Observational studies of this type are carried out in order to:
- Define the risk factors (including those specific for rare diseases)
- Diagnose the causes of diseases (including chronic diseases – cancer, heart disease, metabolic disorders)
Retrospective epidemiological studies are particularly applicable to those ailments which would require very large cohorts or long exposure times to research. They also support the analysis of the epidemiological situation of dynamic populations which demonstrate considerable mobility of participants, and help streamline the evaluation of public health programs.
Methodology of case-control studies
When designing a case-control study, one has to bear in mind the fact that factors which may interfere with the results of the analysis are primarily:
Personal bias when selecting specific people for research and control groups – different ways of participant selection, use of different sources of population
Measurement errors – differences in the accuracy of the exposure indication, and the condition of the control group
Impact of distortion factors on the size of sample group size