Sensitivity, specificity, positive and negative predictive values (%) of admission PCT and CRP values for septic shock
| Screening value | Sensitivity | Specificity | PPV | NPV |
|---|---|---|---|---|
| PCT > 2 ng/ml | 100 | 62 | 69 | 100 |
| PCT > 5 ng/ml | 99 | 78 | 79 | 99 |
| PCT > 10 ng/ml | 88 | 84 | 82 | 90 |
| PCT > 20 ng/ml | 83 | 92 | 90 | 87 |
| CRP > 20 mg/l | 91 | 62 | 66 | 89 |
| CRP > 30 mg/l | 81 | 70 | 69 | 82 |
| CRP > 40 mg/l | 79 | 77 | 74 | 82 |
| CRP > 50 mg/l | 76 | 80 | 76 | 80 |
| PCT > 2 ng/ml and CRP > 20 mg/l | 91 | 78 | 78 | 91 |
| PCT > 20 ng/ml and CRP > 50 mg/l | 69 | 92 | 88 | 78 |
Optimum diagnostic cut off values derived from the ROC curve are shown in bold.
CRP, C reactive protein; NPV, negative predictive value; PCT, procalcitonin; PPV, positive predictive value; ROC, receiver operating characteristic.