CRP and susceptibility to pneumonia measurement: ROC-Curve aspect of the different sub-populations confirmed that these CRP levels can be used in patients with pneumonia (AUC 86.8%; 95% CI, 84.1–89.5) and severe patients (AUC 86.4%; 95% CI, 81.1–91.7) but we must remain cautious in immunosuppressed patients (AUC 82.1%; 95% CI, 70.2–94.0) (Fig. 4).