Epidemiology & Prevention USMLE Step 1 Practice Question
A 62-year-old man presents with a 3-month history of intermittent hematochezia. Vital signs: BP 128/82, HR 92, RR 16, Temp 37.2°C, SpO2 98% on room air. A screening blood test for a colon cancer biomarker currently uses a threshold of 10 units/mL; his level is 8 units/mL. Investigators lower the threshold to 6 units/mL. Hemoglobin is 11.2 g/dL. Recent colonoscopy shows no polyps. Which effect is most likely?
Answer choices
- ANo change in sensitivity or specificity
- BIncreased sensitivity and decreased specificityCorrect answer
- CDecreased sensitivity and decreased specificity
- DDecreased sensitivity and increased specificity
- EIncreased sensitivity and increased specificity
- FDecreased specificity without affecting sensitivity
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