In medicine, sensitivity of a test means positivity in disease. For example if serum antinuclear antibody (ANA) has 100% sensitivity for Systemic Lupus Erythematosus(SLE); which means a negative serum ANA excludes SLE. The use of a test with 100% sensitivity is best used to screen for disease and excludes the disease when the test is negative.
But you already know positive serum ANA does not confirm SLE (DDx: Rheumatoid arthritis, Progressive Systemic Sclerosis).
To calculate the sensitivity of a test; one has to divide TRUE POSITIVE with a total of TRUE POSITIVE plus FALSE NEGATIVE.
| Disease | No Disease | |
| Positive test | True positive | False positive |
| Negative test | False Negative | True Negative |
