Question

A major post office in Washington DC employing 5000 people has been chosen as a site for an anthrax screening program on a trial basis. Although there is a low prevalence of cases, the fatal nature of this disease and the potential risk for employees due to recent threats has generated a proposal to trial this screening program. Use the following data to evaluate the screen in the trial period:

All 5000 employees will be screened. The false negative error rate is noted to be 8%. The false positive error rate is 9%. The prevalence of the disease is found to be 2% at this site.

Construct a 2x2 table to facilitate your calculations and include calculations at the end of the submitted responses to the test.

1. What is the sensitivity of the test in this case?

What does this mean in a sentence?

2. What is the specificity of the test in this case?

What does this mean in a sentence?

3. What is the positive predictive value of this screening test?

What does this mean in a sentence?

4. What is the negative predictive value of this screening test?

What does this mean in a sentence?

5. Given the above information of the screening test – would you recommend that the Post Office continue the screen?

Why or why not?

6. In a town of 4,320 people, the Department of Public Health found 120 people with infectious Ecoli infection in 80 households. A total of 480 people live in the affected homes. Assuming that each household had only one primary case, calculate the secondary attack rate.

Secondary attack rate per 100: ___________

Answer 1

disease Yes I No TP (True Pasiting EP (False Ryting Positive (450) IN (False Negums TN True Neget vel (050) Negative (400) loso Test Result (10) FN = 8 xsooo - 400 I xgooo = 450 100 FP = 100 - TP To = Prevaline 2 = - - FP too TN = 5000 - 95o = 4oso ТР = sensitivity = - + EN Answer 1 Toot4050 selwer 2. - Specificity = - Yaho - TN + FR 4050€ Z 4. PPV - TP - TP + FP NPV = IN EN