Question of the Day

You need a very sensitive test if:

1. Disease is rare (e.g.: BSE)
2. Early Dx improves prognosis (e.g.: HIV in people)
3. The disease is highly lethal or consequences of missing a case are severe (e.g.: rabies, brucellosis, BSE, screw-worm, FMD, EIA)

Remember that a HIGHLY SENSITIVE test will have very FEW false negatives.
That means if a test is highly sensitive, you can TRUST a NEGATIVE TEST.

This sounds contradictory, but it makes more sense if you review this sensitivity diagram.

Sensitivity=a/(a+c). “a” are true positives. “c” are false negatives.
If sensitivity is HIGH then “c” (FALSE negs) must be small.

Therefore, high sensitivity means you can really trust a NEGATIVE result to be correct.