When a screening test's cut-off point is lowered (shifted to include more borderline positives), which of the following changes CORRECTLY describes the expected effect?

• A Sensitivity decreases and specificity increases
• B Both sensitivity and specificity increase
• C Sensitivity increases and specificity decreases ✓
• D PPV increases and sensitivity decreases

Explanation

Lowering the cut-off classifies more individuals as test-positive, capturing more true cases (increasing sensitivity/fewer false negatives) but also classifying more healthy individuals as positive (decreasing specificity/more false positives). Sensitivity and specificity are inversely related for a continuous variable test; there is always a trade-off illustrated by the ROC curve.

Reference: Park's Textbook of Preventive and Social Medicine, 27th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.