16. HCM (part 3)

Question 1

What are the 2 most important criteria according to the World Health criteria for appraising a screening program?

Answer 1

• Condition being screened for must be an important health problem (depends how serious it is and how common it is)
• A suitable screening test must be available to detect early disease w/ acceptable sensitivity and specificity

Question 2

Define sensitivity of a screening test. Equation?

Answer 2

• Ability of a test to detect disease when disease is actually present
• Sensitivity = TP / (TP + FN)

Question 3

Define specificity of a screening test. Equation?

Answer 3

• Ability of a test to exclude disease when disease is absent
• Specificity = TN / (TN + FP)

Question 4

Explain Baye’s Theorem?

Answer 4

The predictive accuracy of any (less than perf) test is proportional to the prevalence of the disease in the population being tested or proportional to the level of risk of the disease in the person being tested

• more prevalence –> better predictive accuracy; lower FP rate
• less prevalence –> worse predictive accuracy; high FP rate

Question 5

What does a true positive test result indicate?

Answer 5

Disease is present

Question 6

What does a false positive test result indicate?

Answer 6

Test said disease is present, but it really isn’t

Question 7

What does a true negative test result indicate?

Answer 7

Disease is not present

Question 8

What does a false negative test result indicate?

Answer 8

Test said disease is not present, but it really is

Question 9

What aspects of a screening test are not dependent on the population the test is used upon?

Answer 9

Sensitivity and specificity

Question 10

What aspect of a screening test does depend on the population being tested?

Answer 10

Predictive accuracy

Question 11

Define predictive accuracy. Equation?

Answer 11

The likelihood that a (+) test is true

PA = TP / (TP + FP)