In pediatric screening, what do sensitivity and specificity describe?

• A. Sensitivity measures true positives; Specificity measures true negatives.
• B. Sensitivity measures false positives; Specificity measures false negatives.
• C. Sensitivity and Specificity both measure only true positives.
• D. Sensitivity measures true negatives; Specificity measures false positives.

Answer: (A)

Sensitivity and specificity describe how well a screening test distinguishes children who have a condition from those who do not. Sensitivity is the ability of the test to correctly identify those who actually have the condition; it’s the proportion of true positives among all children who truly have it. Specificity is the ability to correctly identify those who do not have the condition; it’s the proportion of true negatives among all children who truly do not have it.

In practice, a highly sensitive test catches most affected children (few false negatives), while a highly specific test minimizes identifying healthy children as affected (few false positives). It’s also helpful to remember that false positives are those without the condition who test positive, and false negatives are those with the condition who test negative. Often, there’s a balance or trade-off between sensitivity and specificity depending on how the test threshold is set.