In evidence-based medicine, how is sensitivity defined?

• A. The probability that a test correctly identifies those with the disease (true positive rate).
• B. The probability that a test correctly identifies those without the disease (true negative rate).
• C. The proportion of positive test results that are true positives.
• D. The probability that a negative test result is a true negative.

Answer: (A)

Sensitivity is the ability of a test to correctly identify people who actually have the disease. It equals the proportion of diseased individuals who test positive, i.e., the true positive rate. This matches the concept described in the option. In contrast, specificity refers to correctly identifying those without the disease, while positive predictive value and negative predictive value refer to the likelihood that positive or negative test results are truly positive or negative, respectively.