Author: Bruno, Posted on Saturday, July 03 @ 19:07:56 IST by RxPG  

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Question.

For the calculation of positive predictive value of a screening test, the denominator is comprised of:

1. True positives +False negatives.
2. False positives + True negatives.
3. True positives + False positives.
4. True positives + True negatives.


Answer
3. True positives + False positives.

Reference
Park 16th Edition Page 110
Park 17th Edition Page 111
And all the books mentioned above give this

Quality
Spotter

Status
Repeat

QTDF
Park

Discussion
See the formulae

Explanation
Self Explanatory
Comments
Predictive value reflects the diagnostic power of the test. The ‘predictive value of a positive test’ indicates the probability that a patient with a positive test result has in fact; the disease in question. The more prevalent a disease, in a given population, the more accurate will be the predictive value of a positive screening test. the predictive value of a positive test falls as disease prevalence declines.
• In positive predictive test the denominator is: True positive + False positive.
• In negative predictive test, the denominator is: False negative + True negative

Tips
Another definite question in All India !!


Explanation By Dr Bruno, Author of