What does a high sensitivity (nearing 100%) mean for a diagnostic test?

A high sensitivity of a diagnostic test indicates that the test is very good at identifying individuals who do have the disease, meaning it correctly identifies a high percentage of true positives. When sensitivity is near 100%, it implies that almost all patients with the disease will test positive. Consequently, if the result of such a test is negative, it is very likely that the disease is not present, allowing for the conclusion that a negative result effectively rules out the disease.

This characteristic makes sensitivity crucial in initial screenings, where it is vital to catch as many cases as possible to ensure none are missed. In contrast, a positive result does not guarantee that a person has the disease because of the potential for false positives, nor can it confirm all conditions, nor does it rule in the disease based solely on a negative result.