CASE 1

A rapid screening test was recently developed for detection of Adenovirus strains 8 and 19 which cause

outbreaks of pinkeye. The incidence of pinkeye in the general population is 10%, and the sensitivity and

specificity of the new rapid test is 90% and 85%, respectively.

1. What is the positive predictive value of the new screening test?

2. What is the negative predictive value of the new screening test?

Three years after introduction of the rapid screening test, a vaccine is developed for Adenovirus strains

8 and 19 which reduces the incidence to 5%.

3. What is the positive predictive value of the screening test given the change in incidence?

4. What is the negative predictive value of the screening test given the change in incidence?