Pick the right answer when 2 screening tests are done in series:
(A) Increased sensitivity and decreased specificity (B) Increased specificity and decreased sensitivity (C) Increased sensitivity and increased specificity (D) Decreased sensitivity and decreased specificity
(B) Ans. b. Increased specificity and decreased sensitivitySensitivity: Ability of a screening test to identify correctly all those who have the disease (Cases).Specificity: Ability of a screening test to identify correctly all those who don't have the disease (healthy).Positive predictive value (PPV): Ability of a screening test to identify correctly all those who have the disease, out of all those who test positive on a screening test.Negative predictive value (NPV): Ability of a screening test to identify correctly all those who don't have the disease, out of all those who test negative on a screening test.Screening tests used in the series: where the result of the first test determines whether to run the second test or not.Screening tests used in parallel: where the second test is independently performed regardless of what the first test result is. And, both are done at the same time.If multiple tests are applied in series, the specificity & PPV will increase, the sensitivity & NPV will decrease.If multiple tests are applied in Parallel, the sensitivity & NPV will increase, the specificity & PPV will decrease.