Define sensitivity.

Define sensitivity.

• A. An expression of test accuracy in correctly identifying the absence of a problem as established by a gold standard test
• B. An expression of test accuracy in correctly identifying a problem as established by a gold standard test
• C. The proportion of true positives among all positives
• D. The probability that a person has the condition given a positive test result

Answer: (B)

Sensitivity is the test’s ability to correctly identify people who actually have the condition. It’s the true positive rate: among those whose disease status is confirmed by a gold standard, the fraction that the test marks as positive. For example, if 100 people truly have the disease and the test detects 90 of them, the sensitivity is 90%. A high sensitivity means few missed cases (fewer false negatives), which is especially important in screening. The option that describes this idea correctly focuses on identifying those with the problem; other choices point to specificity (identifying those without the disease), positive predictive value (the proportion of true positives among all positives), or the probability of disease given a positive result (post-test probability/PPV), which are different concepts.

Sensitivity is the test’s ability to correctly identify people who actually have the condition. It’s the true positive rate: among those whose disease status is confirmed by a gold standard, the fraction that the test marks as positive. For example, if 100 people truly have the disease and the test detects 90 of them, the sensitivity is 90%. A high sensitivity means few missed cases (fewer false negatives), which is especially important in screening. The option that describes this idea correctly focuses on identifying those with the problem; other choices point to specificity (identifying those without the disease), positive predictive value (the proportion of true positives among all positives), or the probability of disease given a positive result (post-test probability/PPV), which are different concepts.