Question

QUESTION 38 Calculate the net sensitivity of using both tests in sequence for Test 1 (antinuclear antibodyl: Sensitivity - 60%, Specificity - 70%, Test 2 (American College of Rheumatology critieria); Sensitivitý - 95%, Specificity - 95%? Express your answer as a percentage. QUESTION 39 Calculate the net specificity of using both tests in sequence for Test 1 (antinuclear antibody): Sensitivity - 60%, Specificity = 70%, Test 2 (American College of Rheumatology criteria); Sensitivity - 95%, Specificity - 95%? Express your answer as a percentage rounded to one (1) decimal place if applicable.

Answer 1

We will use the following abbreviations:

The sensitivity of test 1 as sens 1 = 60 % = 0.60

The sensitivity of test 2 as sens 2 = 95% = 0.95

The specificity of test 1 as spec 1 = 70% = 0.70

The specificity of test 2 as spec 2 = 95% = 0.95

Net sensitivity = sens 1 * sens 2

= 0.6 * 0.95

= 0.57 = 57%

Net specificity = spec 1 + spec 2 - spec 1 * spec 2

= 0.7 + 0.95 - 0.7 * 0.95

= 0.985 = 98.5%