Which statement correctly defines sensitivity and specificity?

Which statement correctly defines sensitivity and specificity?

• A. Sensitivity is the true positive rate; specificity is the true negative rate.
• B. Sensitivity is the true negative rate; specificity is the true positive rate.
• C. Sensitivity is the proportion of true negatives among all true negatives.
• D. Sensitivity and specificity are not used with diagnostic tests.

Answer: (A)

Sensitivity and specificity describe how a diagnostic test performs in identifying disease and non-disease. Sensitivity is the true positive rate: among those who actually have the disease, the proportion that test positive. It is calculated as true positives divided by the sum of true positives and false negatives. Specificity is the true negative rate: among those who do not have the disease, the proportion that test negative. It is calculated as true negatives divided by the sum of true negatives and false positives. So stating that sensitivity is the true positive rate and specificity is the true negative rate captures exactly what these metrics measure. The other statements either swap the definitions, misstate what is being measured, or claim these metrics aren’t used for diagnostic tests, which isn’t correct.

Sensitivity and specificity describe how a diagnostic test performs in identifying disease and non-disease. Sensitivity is the true positive rate: among those who actually have the disease, the proportion that test positive. It is calculated as true positives divided by the sum of true positives and false negatives. Specificity is the true negative rate: among those who do not have the disease, the proportion that test negative. It is calculated as true negatives divided by the sum of true negatives and false positives. So stating that sensitivity is the true positive rate and specificity is the true negative rate captures exactly what these metrics measure. The other statements either swap the definitions, misstate what is being measured, or claim these metrics aren’t used for diagnostic tests, which isn’t correct.