Sensitivity, specificity and likelihood ratio values of biomarkers for discrimination of serious bacterial infection at optimal cut-offs
| Biomarker | AUC (95% CI) | Optimal cut-off | Sensitivity | Specificity | LR + | LR − | PPV | NPV |
| WBC, 109/L | 0.632 (0.535 to 0.730) | 13.83 | 50.00% (36.08 to 63.92) | 78.95% (71.03 to 85.53) | 2.38 (1.55 to 3.63) | 0.63 (0.48 to 0.84) | 49.09% (38.70 to 59.56) | 79.55% (74.60 to 83.74) |
| NLR | 0.656 (0.571 to 0.740) | 1.24 | 57.41% (43.21 to 70.77) | 69.17% (60.58 to 76.89) | 1.86 (1.32 to 2.62) | 0.62 (0.44 to 0.86) | 43.08% (34.95 to 51.61) | 79.98% (74.18 to 84.75) |
| ANC, 109/L | 0.681 (0.587 to 0.775) | 6.37 | 53.70% (39.61 to 67.38) | 89.27% (82.57 to 92.93) | 5.01 (3.21 to 7.81) | 0.52 (0.39 to 0.69) | 67.05% (56.58 to 76.06) | 82.59% (78.01 to 86.38) |
| CRP, mg/L | 0.815 (0.747 to 0.883) | 7.2 | 75.47% (61.72 to 86.24) | 75.20% (66.68 to 82.49) | 3.04 (2.16 to 4.28) | 0.33 (0.20 to 0.53) | 55.30% (46.78 to 63.51) | 88.29% (68.27 to 92.44) |
ANC, absolute neutrophil ratio; AUC, area under the curve; CRP, C-reactive protein; LR, likelihood ratio; NLR, neutrophil to lymphocyte ratio; NPV, negative predictive value; PPV, positive predictive value; WBC, white blood cell count.