Which study design compares the number of individuals with and without a disease to identify risk factors?

The case-control study design is specifically structured to compare individuals with a disease (cases) to those without the disease (controls) to identify potential risk factors. This method allows researchers to look retrospectively at how many individuals in each group were exposed to certain risk factors, which can help establish associations between exposures and the disease.

The primary aim of a case-control study is to identify factors that may contribute to the development of a condition by comparing the histories of the cases versus the controls, making it particularly effective for studying rare diseases. This design is beneficial because it often requires fewer resources and less time than other study designs while allowing for the exploration of multiple exposures.

In contrast, longitudinal studies follow subjects over time to observe outcomes, cross-sectional studies analyze data at a single point in time without regard to disease status or exposure history, and cohort studies compare subjects based on their exposure status over time to see who develops the disease. Each of these designs serves different purposes in epidemiological research but does not directly compare diseased and non-diseased groups in the way that case-control studies do.