The effect of lowering the cut off value

[stfidel]

The American Diabetes Association (ADA) recently lowered the cutoff value for fasting glucose used in diagnosing diabetes mellitus from 140 mg/dL to 126 mg/dL. This reference interval change would be expected to produce which of the following alterations?

A. Decrease the test's sensitivity
B. Increase the test's false negative rate
C. Increase the test's negative predictive value
D. Increase the test's positive predictive value
E. Increase the test's specificity

[neoeinstein]

C?........

[Anders]

I would go with D

[shan564]

C.

Negative predictive value essentially means... if the test is negative, what are the chances that I really don't have the disease? If you lower the threshold for diagnosis, a negative result becomes more reassuring. In other words, you'll have fewer people with a negative test who really do have the disease.

The positive predictive value will actually go down. If you have a person with a blood sugar of 130 who is not diabetic, that person will now have a positive test. In other words, you'll have more people with a positive test but no real disease.

[stfidel]

This question was discussed here
http://www.usmle-forums.com/usmle-st...off-value.html