Pre-Work: Home Screening Tests
Instructions: Read the article “Understanding Sensitivity and Specificity with the Right Side of the Brain” along with the scenario below and then answer the following questions.
Scenario: In Irvine, 11,477 people have G6PD deficiency out of a total population of 149,058. As a pharmacy owner in the city, two separate companies have approached you to purchase/place their screening test in your pharmacy. Tests A requires 35 µL of blood, results are available in 5 minutes using the device, and costs $40. Test B requires saliva from a mouth swab, the sample needs to be mailed back to the company for analysis (3 business days for results), and costs $15. The technical specifications of each test is listed below:
Test A can correctly identify 5000 of the 11,477 with G6PD deficiency, but also identifies 13,500 healthy people as having G6PD deficiency
Test B can correctly identify 9000 of the 11,477 with G6PD deficiency, but also identifies 27,000 healthy people as having G6PD deficiency
1. For each test, calculate its sensitivity, specificity, PPV, and NPV
2. If a patient were to purchase this test, clearly and concisely describe in patient friendly language what sensitivity and specificity mean/measure
3. If a patient were to purchase this test, clearly and concisely describe in patient friendly language what positive and negative predictive value mean/measure
4. If the prevalence of G6PD deficiency were to increase, how would this affect the sensitivity/specificity of these tests?
5. If the prevalence of G6PD deficiency were to decrease, how would this affect the positive/negative predictive values of these tests?