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* nb1
 #138450  
  radhe - 11/14/06 11:25
 
  The genetic disease institute at a university hospital has developed a rapid screening test for a serious but treatable inherited metabolic disorder. Although this disorder is predominantly found in a particular ethnic group, it is also found sporadically throughout the entire population. The screening test has a sensitivity of 95% and a specificity of 90%. When used in an ethnically prescreened population where the prevalence of this disorder is 30%, the positive predictive value is 80% and the negative predictive value is 96%. The institute proposes to use this screening test on the general population where the prevalence of this disease is 0.1%. Which of the following is the most likely result of this screening program?

A
) Negative predictive value decreases

B
) Positive predictive value decreases

C
) Sensitivity decreases

D
) Specificity decreases
 
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* rep
#558297
  him_vadodaria - 11/14/06 14:06
 
  you must know BAYES THEOREM
POSITIVE PRID VALUE PROPO TO PREVALENCE ,AND SPECIFICITY AND SENSITIVITY
BEING CONSTANT

so as preve dec. ---PPV--dec. and ---NPV --Increse

ans is....b

 
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* Re:nb1
#558407
  ben - 11/14/06 15:21
 
  PPV -> Test how many people w/ a Positive test Screeining will have disease
NPV -> Test how many poeple w/ Negative Sceeining will not have disease
Prevalence -> The % of People screeined who have disease

So if preval decr so must the PPV and # of People with out diease must therefore incr
 
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