Diagnostic value of serum levels of procalcitonin and C-reactive protein (CRP), and the Clinical Pulmonary Infection Score (CPIS)
| Optimal cut-off | AUC | Sensitivity | Specificity | NPV | PPV | |
| CRP | ≥19.69 mg·dL−1 | 0.714 | 56 | 91 | 89 | 62.5 |
| Procalcitonin | ≥2.99 ng·mL−1 | 0.870 | 78 | 97 | 94 | 87.5 |
| CPIS | ≥6 | 0.873 | 78 | 80 | 93 | 50 |
| Procalcitonin + CPIS# | 0.961 | 67 | 100 | 92 | 100 |
Data are presented as %, unless otherwise stated. AUC: area under the receiver-operating-characteristic curve; NPV: negative predictive value; PPV: positive predictive value. #: for values of both procalcitonin and CPIS above their optimal cut-off.