What characterizes the structure of a Case-Control study?

In a Case-Control study, subjects are identified based on their disease status, which is a key feature of this research design. This means that individuals who have the disease (cases) are compared to individuals who do not have the disease (controls). The primary goal is to investigate whether a certain exposure or risk factor is associated with the disease. By selecting subjects in this way, researchers can examine past exposures or characteristics that may have contributed to the development of the disease. This design is particularly useful for studying rare diseases, as it allows researchers to focus on those who are affected rather than needing to follow a large population over time to see who develops the disease.

Longitudinal tracking of patient outcomes refers to cohort studies where subjects are followed over time to assess the development of outcomes, which is not characteristic of case-control studies. Random assignment of exposure and control groups is a defining feature of randomized controlled trials, not case-control studies. While retrospective data collection can occur in case-control studies, it is not a defining characteristic since data could also be collected prospectively, this is particularly relevant to cohort studies. Hence, identifying subjects based on disease status stands out as the defining characteristic of a Case-Control study.