Question

CA-125 is a marker for the screening of ovarian cancer. To characterize this test, histopathological confirmation of ovarian cancer was done in a cohort of patients. 60/100 women who tested positive for this test had ovarian cancer and 20/100 women who tested negative had ovarian cancer. What is the negative predictive value of this test?

• A. 20/100
• B. 40/100
• C. 60/100
• D. 80/100

Answer 1

The Correct Option is D

The Negative Predictive Value (NPV) of a test is the probability that subjects with a negative test result truly don't have the disease. To calculate the NPV, we use the formula:

NPV = (True Negatives) / (True Negatives + False Negatives)

From the problem statement, we have:

• 20 patients who tested negative had ovarian cancer (False Negatives, FN = 20).
• Assuming 100 total tested negatives, then True Negatives (TN) = 100 - 20 = 80.

Applying the values to the NPV formula:

NPV = 80 / (80 + 20) = 80 / 100 = 0.8

This calculates the NPV to be 80 out of 100, or 80%.