Table 2.
The sensitivity, specificity and likelihood ratio values of NLR, CRP and WBC for discrimination of SBI in infants aged 7–28 days (95% CI)
| Parameter and threshold value | Sensitivity | Specificity | LR+ | LR− | PPV | NPV | |
| NLR | >0.85 | 86.4% (74.1 to 94.4) | 47% (39.5 to 54.6) | 1.6 (1.4 to 2) | 0.3 (0.1 to 0.6) | 30.3% | 92.8% |
| >1 | 72.7% (58.2 to 83.7) | 55.5% (57.8 to 62.9) | 1.6 (1.3 to 2.1) | 0.5 (0.3 to 0.8) | 30.4% | 88.3% | |
| >1.5 | 56.8% (42.2 to 70.3) | 67.7% (60.2 to 73.4) | 1.8 (1.3 to 2.5) | 0.6 (0.5 to 0.9) | 32% | 85.4% | |
| >2 | 52.3% (37.9 to 66.2) | 78% (71.1 to 83.7) | 2.4 (1.6 to 3.6) | 0.6 (0.4 to 0.8) | 38.9% | 85.9% | |
| >3 | 22.7% (12.8 to 37) | 90.9% (85.5 to 94.4) | 2.5 (1.2 to 5.1) | 0.9 (0.72 to 1) | 40% | 81.4% | |
| CRP (mg/L) | >5 | 79.5% (65.5 to 88.9) | 56.7% (49.1 to 64.1) | 1.8 (1.5 to 2.3) | 0.4 (0.2 to 0.7) | 32.9% | 91.1% |
| >20 | 54.4% (40.1 to 68.3) | 89% (83.3 to 92.9) | 5 (3 to 8.3) | 0.5 (0.4 to 0.7) | 56.9% | 87.9% | |
| >40 | 45.5% (31.7 to 59.9) | 97% (93.1 to 98.7) | 14.9 (5.9 to 37.5) | 0.6 (0.4 to 0.7) | 80.2% | 86.9% | |
| >80 | 15.9% (7.9 to 29.3) | 99.4% (96.6 to 99.9) | 26 (3.3 to 206.5) | 0.9 (0.7 to 1) | 87.6% | 81.5% | |
| ANC (103/μL) | >5 | 75% (60.6 to 85.4) | 58.5% (50.9 to 65.8) | 1.8 (1.4 to 2.3) | 0.4 (0.3 to 0.7) | 32.6% | 89.7% |
| >7 | 56.8% (42.2 to 70.3) | 84.1% (7.8 to 89) | 3.6 (2.3 to 5.6) | 0.5 (0.4 to 0.7) | 48.9% | 87.9% | |
| >10 | 34.1% (21.9 to 48.9) | 93.9% (89.1 to 96.7) | 5.6 (2.7 to 11.6) | 0.7 (0.6 to 0.9) | 59.9% | 84.2% | |
| >15 | 13.6% (6.4 to 26.7) | 100% (97.7 to 100) | n/a | 0.9 (0.8 to 1) | 100% | 81.2% | |
| WBC (103/μL) | >10 | 79.5% (65.5 to 88.9) | 39% (31.9 to 46.7) | 1.3 (1.1 to 1.6) | 0.5 (0.3 to 1) | 25.8% | 87.7% |
| >15 | 50% (35.8 to 64.2) | 78% (71.1 to 83.7) | 2.3 (1.5 to 3.4) | 0.6 (0.5 to 0.9) | 37.8% | 85.4% | |
| >20 | 27.3% (16.4 to 41.9) | 85.7% (79.8 to 90.5) | 1.9 (1.1 to 3.6) | 0.9 (0.7 to 1) | 33.8% | 81.5% | |
| >25 | 9.1% (3.6 to 21.2) | 99.4% (96.6 to 99.9) | 14.9 (1.7 to 130) | 0.9 (0.8 to 1) | 80.2% | 80.3% | |
ANC, absolute neutrophil count; CRP, C reactive protein; LR, likelihood ratio; NLR, neutrophils to lymphocytes ratio; NPV, negative predictive value, PPV, positive predictive value; SBI, serious bacterial infection; WBC, white cell count.