Table 4.
Best Thresholds With Diagnostic Accuracy for Mycoplasma pneumoniae–Positive Community-acquired Pneumonia (CAP) Versus M. pneumoniae–Negative CAP in Children
| Parameter | Threshold | Sensitivity (95% CI) | Specificity (95% CI) | Positive LR (95% CI) | Negative LR (95% CI) | AUC (95% CI) |
|---|---|---|---|---|---|---|
| Clinical features | ||||||
| Age, y | >5 | 0.90 (.74–.96) | 0.59 (.42–.74) | 2.18 (1.43–3.31) | 0.18 (.06–.53) | 0.77 (.64–.89) |
| Fever, d | >6 | 0.72 (.54–.85) | 0.76 (.60–.88) | 3.08 (1.61–5.87) | 0.36 (.19–.67) | 0.72 (.59–.86) |
| RTI symptoms, d | >6 | 0.72 (.54–.85) | 0.71 (.54–.83) | 2.46 (1.40–4.34) | 0.39 (.21–.73) | 0.79 (.68–.91) |
| Biomarkers | ||||||
| PCT, μg/L | <0.25 | 0.97 (.83–.99) | 0.56 (.39–.71) | 2.19 (1.49–3.21) | 0.06 (.01–.43) | 0.81 (.70–.92) |
| CRP, mg/L | <50 | 0.86 (.69–.95) | 0.62 (.45–.76) | 2.25 (1.44–3.54) | 0.22 (.09–.58) | 0.76 (.63–.88) |
| WBC count, ×109 cells/L | <18.00 | 0.95 (.77–.99) | 0.38 (.22–.57) | 1.55 (1.13–2.13) | 0.12 (.02–.89) | 0.71 (.56–.86) |
| ANC, ×109 cells/L | <8.00 | 0.67 (.45–.83) | 0.60 (.41–.77) | 1.67 (.94–2.94) | 0.56 (.28–1.10) | 0.71 (.56–.86) |
| Combination | ||||||
| Age + fever + RTI symptoms | As defined above | 1.00 (.88–1.00) | 0.44 (.29–.61) | 1.79 (1.33–2.41) | NA | 0.82 (.71–.92) |
| Age + fever + RTI symptoms + PCT | As defined above | 1.00 (.88–1.00) | 0.32 (.19–.49) | 1.48 (1.17–1.87) | NA | 0.90 (.83–.97) |
The threshold is the optimal cutoff that maximizes the distance to the identity (diagonal) line in the receiver operating characteristic curve in Figure 2 according to the Youden J statistic using the “coords” function in R software environment (version 3.6.0) [22].
Abbreviations: ANC, absolute neutrophil count; AUC, area under the receiver operating characteristic curve; CI, confidence interval; CRP, C-reactive protein; LR, likelihood ratio; NA, not available; PCT, procalcitonin; RTI, respiratory tract infection; WBC, white blood cell.