Evidence based emergency medicine part 2: positive and negative predictive values of diagnostic tests

ABSTRACT

In volume 3, number 2, pages 48-49, we explained some screening characteristics of a diagnostic test in an educational manuscript entitled "Simple definition and calculation of accuracy, sensitivity and specificity" [1]. The present article was aimed to review other screening performance characteristics including positive and negative predictive values [PPV and NPV]. PPV and NPV are true positive and true negative results of a diagnostic test, respectively [2]. In other words, if a subject receives a certain diagnosis by a test, predictive values describe how likely it is for the diagnosis to be correct