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Old 09-18-2012
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Default Epidemiology case

The cut-off value of normal prostate-specifi c
antigen levels is 4.0 ng/dL. If this value were to
be decreased to 3.7 ng/dL, the sensitivity and
specifi city of the test for detecting prostate cancer
will change. How would lowering the normal
value of prostate-specifi c antigen in cancer
screening alter the number of false-positives
and false-negatives?

(A) Decrease both false-positives and falsenegatives
(B) Decrease the number of false-negatives
and increase the number of false-positives
(C) Increase both false-positives and falsenegatives
(D) Increase the number of false-negatives and
decrease the number of false-positives
(E) It would not change either parameter
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Old 09-18-2012
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(B) Decrease the number of false-negatives
and increase the number of false-positives

Sensitivity will go up and specificity will go down.

Therefore, FN (denominator for sensitivity will decrease) and FP (denominator for specificity will increase)
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Old 09-19-2012
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Answer B. Uworld has a question on this concept ,but different Q.

All positives will increase -true positives and false positive .

all negative will decrease- true negatives and false negatives
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Old 02-23-2016
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B

By bringing the cut-off value closer to the normal range, more people without prostate cancer will test positive. Thus, the number of false positives will increase.

As well, decreasing the cut-off value will allow for detection of prostate cancer in people with a PSA value between 3.7 and 4. This would decrease the number of false negatives.
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