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a55 yrs old man visits his primary care physician with a complaint of urinary frequency.examination finds a 1 cm nodule on his prostate gland ,the physician orders a prostete specific ag serum test ,by common standard a psy level greater than 4 ng/ml is considered abnl ,using this standard this test has 80%sensitivity and 90%specificity ,a recently published epidemiologic article found that in a cross sectional study ,10% of men of this age have prostate cancer ,the result on this pt is 7 ,what is ur best estimate of liklihood that this man actually has prostate cancer?
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u have sen, spec and prevalence.
take any number for the sample (N), and draw 2X2 table and figure it out.
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thanks u r trying to help
i have done that already but tell me what 10% has to do with this?
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can any body tell me is this q asking for ppv or not ?
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and if it is how to correlate it with prevalence/
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Considering N= 100
TP= 8
Fp=2
FN= 9
Tn=81
PPV= Tp/Tp+Fn
=approximately 50%
