In the context of calculating sensitivity, which elements are used in the numerator?

Sensitivity, also known as the true positive rate, is a measure used to evaluate the performance of a diagnostic test. It quantifies the ability of the test to correctly identify individuals who have a particular disease or condition. The formula for sensitivity is as follows:

Sensitivity = True Positives / (True Positives + False Negatives)

In this context, the numerator specifically consists of true positives, which are the cases that the test correctly identifies as having the condition. This aspect is crucial because it directly reflects the test's capacity to detect the disease effectively.

False negatives, which are cases where the test fails to identify the condition despite its presence, are included in the denominator because they represent instances where the test did not perform correctly. Therefore, true positives are critical for understanding how well the test can identify the condition for those who truly have it.

This understanding is foundational for interpreting diagnostic tests in phlebology and other medical fields, emphasizing the importance of a high sensitivity in tests designed to detect medical conditions accurately.