Which of the following statements about screening tests are correct? (Select all that apply)
A)The sensitivity of a test is the proportion of all persons who have the disease who test positive
B)The predictive value of a negative test (or negative predictive value, NPV) is not affected by the sensitivity of the test
C)The prevalence of the disease of interest does not affect the accuracy of a screening test
D)The prevalence of the disease of interest does not affect the performance of a screening test
E)The specificity of a test is the proportion of all those who do not have the disease who test positive
F)Across‐sectionalsurveyisthebeststudydesigntoassesstestaccuracy

Question

Quizplus · Accepted Answer

An insensitive test (B) will increase the number of false
negatives, thus increasing the denominator of the NPV (true negatives ÷ all those who
test negative) thereby decreasing the NPV.The specificity is actually the complement of
E, i.e.the proportion of those who do not have the disease who test negative.While the
prevalence of a disease does not affect the accuracy (sensitivity and specificity) of a
screening test, it will affect the performance of the test in practice (D).It is a good idea to
think these measures (sensitivity, specificity, predictive values) through to be sure you
are comfortable with what each is measuring.

Which of the Following Statements About Screening Tests Are Correct