Which option describes a case-control study?

Which option describes a case-control study?

• A. Obtaining histories and other information from a group of known cases and from a comparison group to determine the relative frequency of a characteristic or exposure under study
• B. Study of past mortality or morbidity trends to permit estimates of future disease occurrence
• C. Study of the incidence of cancer in men who have quit smoking
• D. Analysis of previous research in different places and under different circumstances to permit the establishment of hypotheses based on cumulative knowledge

Answer: (C)

Case-control studies start with two groups based on outcome: people who already have the disease and a group without the disease. Then researchers look back in time to determine how many in each group were exposed to a suspected risk factor. By comparing exposure frequencies between cases and controls, you can estimate the strength of the association between the exposure and the disease, usually expressed as an odds ratio. This design is especially efficient for studying rare diseases and can examine multiple exposures after the outcome is known. Other descriptions fit different designs: projecting future disease from past mortality or morbidity trends is a time-series/projection approach; studying the incidence of cancer in men who quit smoking describes following groups over time to see new cases, which is a cohort study; and analyzing previous research to form hypotheses is a literature review.

Case-control studies start with two groups based on outcome: people who already have the disease and a group without the disease. Then researchers look back in time to determine how many in each group were exposed to a suspected risk factor. By comparing exposure frequencies between cases and controls, you can estimate the strength of the association between the exposure and the disease, usually expressed as an odds ratio. This design is especially efficient for studying rare diseases and can examine multiple exposures after the outcome is known. Other descriptions fit different designs: projecting future disease from past mortality or morbidity trends is a time-series/projection approach; studying the incidence of cancer in men who quit smoking describes following groups over time to see new cases, which is a cohort study; and analyzing previous research to form hypotheses is a literature review.