Question

A particular diagnostic test for disease X has a sensitivity of 90% and a specificity of 90%. What is the negative predictive value of the test?

90%
10%
1%
18%
It cannot be determined from the information given.

Answer 1

Sensitivity is the proportion of true positives that are correctly identified by the test.
Specificity is the proportion of true negatives that are correctly identified by the test.

Answer 2

Positive predictive value = the proportion of patients with positive test results who are correctly diagnosed.
Negative predictive value = the proportion of patients with negative test results who are correctly diagnosed.

Answer 3

NPV = (specificity*(1-prevalence))/((1-sensitivity)*prevalence+specificity*(1-prevalence))

Answer 4

It cannot be determined from the information given. Right?

Answer 5

That is right, unless you know the ratio of positive tests vs negative tests or the ratio of deseased vs non deseased