What does sensitivity measure in medical testing?

Sensitivity in medical testing refers to the ability of a test to correctly identify individuals who have a specific disease. It is defined as the proportion of true positives among all patients who actually have the disease. Specifically, sensitivity is calculated as the number of true positive results divided by the sum of true positive and false negative results. This measurement is crucial because a test with high sensitivity will detect most patients who have the disease, minimizing the risk of missed diagnoses.

The significance of sensitivity is particularly evident in conditions where early detection can significantly impact treatment outcomes. A highly sensitive test is desirable in screening situations, where it is important to identify as many individuals with the disease as possible, even at the expense of a few false positives.

The other options do not accurately represent the concept of sensitivity. For instance, the first option relates to specificity, which measures the proportion of true negatives among patients without the disease. The third option regarding further testing does not pertain directly to sensitivity but rather to decision-making based on test results. Lastly, the fourth option describes false positives, which are not a measure of sensitivity but rather represent errors in test accuracy that sensitivity aims to mitigate.