Table 3.
Performance of laboratory tests in the diagnosis of infected nonunion
| WBC | CRP | ESR | D-dimer | |
|---|---|---|---|---|
| False positive, n | 2 | 4 | 5 | 3 |
| True negative, n | 32 | 30 | 29 | 31 |
| True positive, n | 4 | 13 | 18 | 24 |
| False negative, n | 28 | 19 | 14 | 8 |
| Sensitivity (95% CI) | 12.5% (4.08–29.93) | 40.6% (24.21–59.21) | 56.3% (37.88–73.16) | 75.0% (56.25–87.87) |
| Specificity (95% CI) | 94.1% (78.94–98.97) | 88.2% (71.61–91.16) | 85.3% (68.17–94.46) | 91.2% (75.19–97.69) |
| PPV (95% CI) | 66.7% (24.11–94.00) | 76.5% (49.76–92.18) | 78.3% (55.79–91.71) | 88.9% (69.70–97.09) |
| NPV (95% CI) | 53.3% (40.10–66.14) | 61.2% (46.24–74.46) | 67.4% (51.34–80.46) | 79.5% (63.06–90.13) |
Abbreviations: WBC, white blood cell; CRP, C-reactive protein; ESR, erythrocyte sedimentation rate; PPV, positive predictive value; NPV, negative predictive value.