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Table 4 Sensitivity, specificity, PPV, NPV, and accuracy of inflammatory markers

From: Synovial fluid IL-1β appears useful for the diagnosis of chronic periprosthetic joint infection

Parameters ESR (mm/h) CRP (mg/L) SF IL-1β (pg/ml) SF PMN (%) SF IL-1β +CRP SF IL-1β+ PMN%
AUC (95%CI) 0.627 (0.521, 0.725) 0.712 (0.609, 0.801) 0.991 (0.945, 1.000) 0.981 (0.928, 0.998) / /
Cutoff level 34 13 312.7 69.96 SF IL-1β>312.7
+CRP>13
SF IL-1β>312.7+ PMN%>69.96
Sensitivity (%) (95%CI) 54.05 (36.9, 70.5) 89.19 (74.6, 97.0) 97.30 (85.8, 99.9) 94.59 (81.8, 99.3) 86.49 (70.43, 94.92) 91.89 (76.98, 97.88)
Specificity (%) (95%CI) 78.57 (65.6, 88.4) 50.00 (36.3, 63.7) 94.64 (85.1, 98.9) 92.86 (82.7, 98.0) 96.43 (86.62, 99.38) 100 (92.00,100)
PPV (%) 62.50 54.10 92.31 89.74 94.12 100
NPV (%) 72.13 87.50 98.15 96.30 91.53 94.92
Accuracy (%) 68.82 65.59 95.70 93.55 92.47 96.77
  1. CRP C-reactive protein, ESR erythrocyte sedimentation rate, CI confidence interval, PPV positive predictive value, NPV negative predictive value