Determining the Sensitivity and Specificity for a Test Based on its Positive and Negative Likelihood Ratios

The sensitivity (S) and specificity (E) of a test can be calculated from the positive and negative likelihood ratios (LR).

positive likelihood ratio =

= (sensitivity) / (1 - (specificity))

negative likelihood ratio =

= (1 - (sensitivity)) / (specificity)

If these are rearranged:

specificity =

= ((positive LR) – 1) / ((positive LR) – (negative LR))

sensitivity =

= (positive LR) * (1 – (negative LR)) / ((positive LR) – (negative LR))

To read more or access our algorithms and calculators, please log in or register.