Eli5 – Efficacy, sensitivity and specificity of a clinical study

Question

Please can someone explain what these mean exactly? For context I am looking at the study of Ottawa ankle rules. This study looked to develop a set of rules that could be used in order to detect significant ankle fractures

In: 3

Answer 1

Broadly speaking:

– Efficacy: does a treatment do the main thing we want it to?

– Sensitivity: does a test/assessment pick up on the thing we want it to measure?

– Specificity: when that test/assessment registers positive, how often is it a false positive?

Without looking up that particular study, I imagine sensitivity/specificity applies to their method of detecting fractures. Efficacy as a term is more used to describe treatments, and doesn’t usually refer to diagnostic tests.