Table 3

Predictors of SBI

BiomarkerCut-offSensitivity (95% CI)Specificity (95% CI)PPV (95% CI)NPP (95% CI)LR+ (95% CI)LR− (95% CI)
Lactate≥4 mmol/l38.1% (23.6 to 54.4)89.7% (86.5 to 92.3)25% (15.0 to 37.4)94.1% (91.5 to 96.1)3.7 (2.3 to 5.9)0.7 (0.5 to 0.9)
Lactate≥2.5 mmol/l66.7% (50.5 to 80.4)66.2% (61.7 to 70.5)15.1% (10.3 to 21.1)95.6% (92.8 to 97.6)2.0 (1.5 to 2.5)0.5 (0.3 to 0.8)
WBC<5 or ≥15×109/l51.2% (35.1 to 67.1)73.8% (69.4 to 77.8)15.2% (9.7 to 22.3)94.3% 91.2 to 96.5)2.0 (1.4 to 2.7)0.7 (0.5 to 0.9)
CRP≥50 mg/l36.8% (21.8 to 54.1)83.6% (79.4 to 87.2)18.9% (10.8 to 29.7)92.7% (89.3 to 95.3)2.2 (1.4 to 3.6)0.8 (0.6 to 1.0)
  • CRP, C-reactive protein; LR, likelihood ratio; NPV, negative predictive value; PPV, positive predictive value; SBI, serious bacterial infection; WBC, white blood cell count.