Table 4

Diagnostic accuracy of CRP, abnormal white cell count (<5000/uL or >15 000/uL) and elevated neutrophil count (>10 000/uL) at predicting meningococcal disease

TestSensitivity (95% CI)Specificity (95% CI)PPV (95% CI)NPV (95% CI)Positive LHR (95% CI)Negative LHR (95% CI)
CRP>6 mg/L1.00 (0.46 to 1.0)0.29 (0.23 to 0.35)0.03 (0.01 to 0.06)1.00 (0.94 to 1.00)1.4 (1.3 to 1.5)NA
CRP≥10 mg/L1.00 (0.46 to 1.0)0.39 (0.33 to 0.45)0.03 (0.01 to 0.07)1.00 (0.95 to 1.00)1.6 (1.5 to 1.8)NA
CRP≥20 mg/L1.00 (0.46 to 1.0)0.54 (0.47 to 0.60)0.04 (0.01 to 0.10)1.00 (0.96 to 1.00)2.2 (1.9 to 2.5)NA
CRP≥50 mg/L0.60 (0.17 to 0.93)0.78 (0.73 to 0.83)0.05 (0.01 to 0.15)0.99 (0.96 to 0.99)2.8 (1.3 to 6.0)0.5 (0.2 to 1.5)
Abnormal white cell count0.60 (0.17 to 0.93)0.67 (0.61 to 0.73)0.03 (0.01 to 0.11)0.99 (0.95 to 1.00)1.8 (0.9 to 3.9)0.6 (0.2 to 1.7)
Elevated neutrophil count0.40 (0.07 to 0.83)0.73 (0.67 to 0.78)0.03 (0.00 to 0.11)0.98 (0.95 to 1.00)1.5 (0.5 to 4.4)0.8 (0.4 to 1.7)
  • CRP, C reactive protein; LHR, likelihood ratio; NPV, negative predictive value; PPV, positive predictive value.