Table 1.
Diagnostic test accuracy summary statistics [2]
| Summary statistics | Equation | Definition |
|---|---|---|
| Sn | TP/(TP+FN) | Proportion of persons who have positive test results to those with disease |
| Sp | TN/(FP+TN) | Proportion of persons who have negative test result to those without disease |
| PPV | TP/(TP+FP) | Proportion of persons with disease to those who have positive test result |
| NPV | TN/(FN+TN) | Proportion of persons without disease to those who have negative test result |
| LR+ | Sn/(1-Sp) | Ratio of the probability of a positive test result among those with disease to that of a positive test result among those without disease |
| LR- | (1-Sn)/Sp | Ratio of the probability of a negative test result among those with disease to that of a negative test result among those without disease |
| Accuracy of index test | (TP+TN)/(TP+FP+FN+TN) | The proportion of persons who are true positive and persons who are true negative among all subjects |
| DOR | (TP*TN)/(FP*FN) | The ratio of the OR for a positive test result among persons with disease to that among persons without disease |
Sn, sensitivity; Sp, specificity; PPV, positive predictive value; NPV, negative predictive value; LR+, positive likelihood ratio; LR-, negative likelihood ratio; DOR, diagnostic odds ratio; TP, true positive; FP, false positive; FN, false negative; TN, true negative; OR, odds ratio.