What does positive predictive value (PPV) measure?

Positive predictive value (PPV) is a statistic that measures the probability that individuals with a positive test result truly have the disease. It is calculated by taking the number of true positives (those who do have the disease and tested positive) divided by the total number of positive test results (including both true positives and false positives). This means that a high PPV indicates that a positive result from the test is likely to be correct, which is crucial in clinical practice for making informed decisions about patient care.

For instance, in screening for a particular condition, a high PPV suggests that when the test indicates the presence of the disease, the likelihood of actual disease is significant. This is particularly important in situations where treatment decisions will be based on the test results. The utility of PPV in clinical settings emphasizes its role in the overall accuracy of diagnostic tests and their implications for patient management.