Test sensitivity and specificity are reciprocal to each other, such that when one is increased, the other is decreased and it will almost always cause a corresponding change in the other. If the sensitivity is increased to ensure the capture of all positives, the results will also include some false positives because the specificity has decreased.
Conversely, if an assay’s test threshold (cut-off for positivity) is high, to exclude any false negatives, the results will include some false negatives because the sensitivity has decreased.
In general:
- Increases in sensitivity (lower threshold cut-off values for +); more false-positive test results (Note: This is most apparent when the prevalence of the disease state is low.)
- Increases in specificity (higher threshold cut-off values for +); more false-negative test results (Note: This is most apparent when the prevalence of the disease state is high.)
