In a small pilot study, 12 women with endometrial cancer and 12 controls matched on age, race, weight, and parity, and asked about estrogen use, what study design is this?

In a small pilot study, 12 women with endometrial cancer and 12 controls matched on age, race, weight, and parity, and asked about estrogen use, what study design is this?

• A. Concurrent cohort
• B. Retrospective cohort
• C. Case-control
• D. Cross-sectional

Answer: (C)

This design starts with people who have the disease and a comparable group without the disease, then looks back to see who was exposed. Here, 12 women with endometrial cancer (cases) and 12 matched controls were identified, and afterward their estrogen use was assessed. That backward-looking comparison of exposure between those with and without the outcome is the hallmark of a case-control study. Matching on factors like age, race, weight, and parity helps control for those potential confounders so any association with estrogen use is not simply due to those differences. It’s not a cohort study, because you don’t begin with exposure status and follow people to see who develops the disease; it’s not cross-sectional, which would assess exposure and disease at the same time; and it isn’t a retrospective cohort, which would start with exposure and look backward for disease in a defined exposed vs unexposed group.

This design starts with people who have the disease and a comparable group without the disease, then looks back to see who was exposed. Here, 12 women with endometrial cancer (cases) and 12 matched controls were identified, and afterward their estrogen use was assessed. That backward-looking comparison of exposure between those with and without the outcome is the hallmark of a case-control study. Matching on factors like age, race, weight, and parity helps control for those potential confounders so any association with estrogen use is not simply due to those differences. It’s not a cohort study, because you don’t begin with exposure status and follow people to see who develops the disease; it’s not cross-sectional, which would assess exposure and disease at the same time; and it isn’t a retrospective cohort, which would start with exposure and look backward for disease in a defined exposed vs unexposed group.