What type of measure is typically used in case-control studies to assess exposure?

In case-control studies, the odds ratio is commonly used to assess the association between exposure and outcome. This is because case-control studies start with an outcome (or disease) and look backward to determine exposure status. The odds ratio compares the odds of exposure among cases (those with the outcome) to the odds of exposure among controls (those without the outcome).

By calculating the odds of being exposed for both groups, researchers can infer whether the exposure might be related to the disease. The odds ratio provides a measure of strength and direction of the association, helping to determine if those who have the disease were more likely to have been exposed compared to those who do not have the disease. This makes it particularly suitable for situations where the outcome is already known and influences the analysis of the data.

Other measures, such as risk ratio and incidence rate, are typically applied in cohort studies where the direction of time is from exposure to outcome, and they require a different study design that tracks the development of disease over time rather than starting with the disease. Therefore, the odds ratio is the appropriate measure for analyzing exposure in case-control studies.