Combined predictors of SBI
| Combination of biomarkers | Sensitivity (95% CI) | Specificity (95% CI) | PPV (95% CI) | NPV (95% CI) | LR+ (95% CI) | LR− (95% CI) |
| Lactate and WBC | 22.0% (10.6 to 37.6) | 96.4% (94.2 to 97.9) | 36.0% (18.0 to 57.5) | 93.1% (90.4 to 95.2) | 6.1 (2.9 to 13.0) | 0.8 (0.7 to 1.0) |
| Lactate and CRP | 10.5% (4.2 to 24.1) | 98.1% (96.1 to 99.1) | 36.4% (15.2 to 64.6) | 91.3% (88.1 to 93.7) | 5.5 (1.7 to 17.9) | 0.9 (0.8 to 1.0) |
| WBC and CRP | 21.1% (9.6 to 37.3) | 91.6% (88.2 to 94.3) | 21.1% (9.6 to 37.3) | 91.6% (88.2 to 94.3) | 2.5 (1.2 to 5.1) | 0.9 (0.7 to 1.0) |
| Lactate and WBC and CRP | 5.3% (1.5 to 17.3) | 99.2% (97.6 to 99.7) | 40.0% (11.8 to 76.9) | 91.0% (87.7 to 93.4) | 6.4 (1.1 to 37.1) | 1.0 (0.9 to 1.0) |
Lactate ≥4 mmol/l; WBC <5 or ≥15×109/l; CRP ≥50 mg/l.
CRP, C-reactive protein; LR, likelihood ratio; NPV, negative predictive value; PPV, positive predictive value; SBI, serious bacterial infection; WBC, white blood cell count.