Which test performance term defines the percentage of individuals with a disease who test positive?

The term that defines the percentage of individuals with a disease who test positive is sensitivity. Sensitivity measures the proportion of true positives in a population with the disease, indicating how effectively a test identifies individuals who actually have the condition. High sensitivity is crucial in screening tests, as it minimizes false negatives, ensuring that most individuals with the disease are correctly identified and can receive appropriate care. This concept is vital for clinicians and healthcare providers to understand, as it directly impacts the reliability of a test in diagnosing diseases.

In contrast, specificity refers to a test's ability to identify those without the disease, while positive predictive value (PPV) reflects the probability that individuals who test positive truly have the disease. Prevalence describes how common a disease is within a population but does not directly relate to test performance in identifying affected individuals.