Table 4.
Accuracy of Laboratory Studies
| Laboratory Measurement (Cutoff or Range) by Source |
Sensitivity | Specificity | Positive Likelihood Ratio (95% Confidence Interval) |
Negative Likelihood Ratio (95% Confidence Interval) |
|---|---|---|---|---|
| White blood cell count, /μL | ||||
| Summary, >14 900 or >15 000 | 1.7 (0.83-3.4) | 0.77 (0.52-1.1) | ||
| Peltola et al,45 1986 (>14 900) | 0.60 | 0.84 | 3.7 (2.1-6.5) | 0.48 (0.37-0.63) |
| Paajanen et al,52 1997 (>15 000) | 0.56 | 0.44 | 1.0 (0.71-1.4) | 1.0 (0.64-1.5) |
| Miskowiak and Burcharth,56 1982 (>15 000) | 0.19 | 0.85 | 1.3 (0.42-3.8) | 1.0 (0.75-1.2) |
| Summary, >10 000 or >10 100 | 2.0 (1.3-2.9) | 0.22 (0.17-0.30) | ||
| Pearl et al,20 1995 (>10 000) | 0.90 | 0.38 | 1.5 (1.3-1.6) | 0.26 (0.20-0.34) |
| Wu et al,38 2003 (>10 000) | 0.92 | 0.29 | 1.3 (1.1-1.6) | 0.26 (0.14-0.49) |
| Harland,43 1991 (>10 000) | 0.92 | 0.70 | 3.1 (1.9-4.8) | 0.11 (0.06-0.20) |
| Van den Broek,53 2004 (>10 100) | 0.80 | 0.76 | 3.4 (1.8-6.3) | 0.26 (0.16-0.44) |
| Kharbanda et al,37 2005 (>8850) | 0.98 | 0.40 | 1.6 (1.5-1.8) | 0.06 (0.02-0.17) |
| Türkyilmaz et al,51 2006 (age-specific)a | 0.70 | 0.79 | 3.4 (1.9-6.3) | 0.37 (0.24-0.56) |
| Absolute neutrophil count, /μL | ||||
| Kharbanda et al,37 2005 (>6750) | 0.97 | 0.51 | 2.0 (1.7-2.2) | 0.06 (0.03-0.16) |
| C-reactive protein, mg/L | ||||
| Mikaelsson and Arnbjornsson,46 1984 | ||||
| ≥25 | 5.2 (1.7-16)b | |||
| 13-24 | 0.23 (0.12-0.43)b | |||
| ≤12 | 1.1 (0.79-1.6)b | |||
| Rodriguez-Sanjuan et al,49 1999 (>17) | 0.58 | 0.80 | 2.9 (1.2-7.0) | 0.53 (0.39-0.72) |
| Peltola et al,45 1986 (>10) | 0.64 | 0.82 | 3.6 (2.1-6.2) | 0.44 (0.33-0.59) |
| Paajanen et al,52 1997 (>10) | 0.85 | 0.33 | 1.3 (1.0-1.6) | 0.45 (0.20-0.98) |
| Wu et al,38 2003 (>8) | 0.79 | 0.44 | 1.4 (1.1-1.8) | 0.47 (0.31-0.72) |
| Erythrocyte sedimentation rate, mm/h | ||||
| Peltola et al,45 1986 (>20) | 0.39 | 0.90 | 3.8 (1.8-8.1) | 0.68 (0.56-0.81) |
| Urinalysis | ||||
| Paajanen and Somppi,55 1996 | ||||
| >3 White blood cells per high-power field | 0.27 | 0.90 | 2.6 (0.99-7.0) | 0.81 (0.66-1.00) |
| >3 Red blood cells per high-power field | 0.05 | 0.90 | 0.48 (0.10-2.3) | 1.1 (0.94-1.2) |
| Positive bacteria culture | 0.02 | 1.00 | 3.6 (0.15-85.4) | 1.0 (0.91-1.0) |
a
Upper limit of normal defined as 15 000/μL for ages 3 to 10 years and 13 000/μL for ages 11 to 16 years.
b
Stratum-specific likelihood ratios.