Test characteristics for WBC decision thresholds (n = 66)*
| WBC threshold (109 cells/l) | Sensitivity (%) | Specificity (%) | PPV* (%) | NPV* (%) | LR+ | LR− |
|---|---|---|---|---|---|---|
| *The prevalence of bacterial infections in our study population was 12%. Neonates classified as having pneumonia were excluded from this analysis. | ||||||
| LR+, likelihood ratio for a positive test; LR−, likelihood ratio for a negative test; NPV, negative predictive value; PPV, positive predictive value. | ||||||
| 5 | 100 | 2 | 12 | 100 | 1.0 | 0.0 |
| 10 | 100 | 31 | 17 | 100 | 1.4 | 0.0 |
| 12 | 75 | 53 | 18 | 94 | 1.6 | 0.5 |
| 15 | 50 | 74 | 21 | 91 | 1.9 | 0.7 |
| 17 | 38 | 89 | 33 | 91 | 3.8 | 0.7 |
| 20 | 0 | 93 | 0 | 87 | 0.0 | 1.1 |
| 22 | 0 | 97 | 0 | 88 | 0.0 | 1.0 |
| 25 | 0 | 98 | 0 | 88 | 0.0 | 1.0 |