What does sensitivity measure in the context of diagnostic testing?

Sensitivity in the context of diagnostic testing refers to the ability of a test to correctly identify individuals who have a particular disease. It is defined as the proportion of true positive results among those who are actually affected by the disease. In other words, sensitivity measures how many patients with the disease produce a positive test result, making it a critical metric for determining how effectively a diagnostic tool detects the presence of a condition.

A high sensitivity means that the test is good at identifying those with the disease, minimizing the risk of false negatives—instances where the test fails to detect the disease in individuals who are actually affected. This property is particularly valuable in screening situations where it is important to catch as many cases as possible to provide timely treatment.

In contrast, other choices describe different statistical measures or aspects of diagnostic tests that do not pertain to sensitivity. For example, some options might describe specificity, the incidence of false positives, or the general confirmatory ability of a test, which are separate concepts from the measurement of sensitivity.