A physical examination,digital rectal exam,was used to screen for prostate cancer in 290 men with biopsy-proven prostate cancer and in 516 age- and race-matched control men,all of whom showed no evidence of cancer at biopsy.The results of the physical examination were positive in 136 cases and in 165 control men.Now,the health commissioner in City A decides to use a physical exam,digital rectal exam,as a primary screening test for prostate cancer.What will be the positive predictive value of the physical examination?
A) 45%
B) 47%
C) 68%
D) 82%
E) Cannot calculate it based on given information

Question

Quizplus · Accepted Answer

To calculate the positive predictive value,we should have a prevalence of the disease in the population.However,in this question,we do not have any information on the prevalence of the disease.Therefore we cannot calculate the positive predictive value.Positive predictive value equals the "number of people who were identified as diseased by the test among who actually have the disease" divided by the "total number of people who were identified as diseased by the test."

A Physical Examination,digital Rectal Exam,was Used to Screen for Prostate