Question

If 50% of women who are diagnosed with venous thrombosis are found to be taking oral contraceptives compared to those without thrombosis, which type of study is this?

• A. Cohort
• B. Case Study
• C. Cross-Sectional
• D. ANOVA

Hint:

Case-control studies are retrospective and useful for studying rare diseases and their risk factors.

Answer 1

The Correct Option is B

A case study (more specifically a case-control study in epidemiology) compares subjects with a particular condition (cases) to those without the condition (controls) to identify factors that may be associated with the condition. - Here, women diagnosed with venous thrombosis (cases) are compared to women without thrombosis (controls) based on oral contraceptive use.
- A cohort study follows a group over time to see who develops the outcome; not applicable here since the data is retrospective.
- Cross-sectional studies measure exposure and outcome simultaneously at a single point in time, not comparing based on disease presence retrospectively.
- ANOVA is a statistical test used to compare means across groups, not a study design.
Therefore, this study is a case study (case-control) design.

Answer 2

The scenario compares women who already have venous thrombosis against those who do not, then looks back at how many in each group were taking oral contraceptives. Match this design against each option.

1. Cohort: A cohort study starts with a group defined by exposure status, such as oral contraceptive users versus non-users, and follows them forward in time to see who develops the outcome. Here the starting point is disease status, not exposure status, and there is no forward follow-up, so this option is incorrect.
2. Case Study: This describes a case-control design, where subjects are first grouped by whether they have the disease, cases with venous thrombosis and controls without it, and their past exposure to oral contraceptives is then compared between the two groups. That is exactly the setup described, so this option is correct.
3. Cross-Sectional: A cross-sectional study measures exposure and outcome at the same single point in time in one sample, without dividing subjects by disease status first. The scenario instead starts from disease status and looks backward at exposure, so this option is incorrect.
4. ANOVA: ANOVA is a statistical test for comparing means across three or more groups, not a way of designing a study or collecting data, so it cannot be the answer to a question asking about study design, making this option incorrect.

The design that starts from disease status and looks backward at past exposure is the case-control design.

Therefore, the correct answer is Case Study.