Table 1

Diagnostic statistics of dichotomised biomarkers

S100A12MRP8/14*hsCRPS100A12 or hsCRPMRP8/14 or hsCRP
Positive predicted outcome if … (cut-off level)*≥175 ng/ml≥690 ng/ml≥0.3 mg/dlS100A12 ≥175 ng/ml or hsCRP ≥0.3 mg/dlMRP8/14 ≥690 ng/ml or hsCRP ≥0.3 mg/dl
Flare within 0–3 months after treatment withdrawal
Sensitivity, % (95% CI)67 (38 to 88)87 (60 to 98)29 (8 to 58)79 (49 to 95)93 (66 to 100)
Specificity, % (95% CI)84 (77 to 89)64 (57 to 71)87 (81 to 91)75 (68 to 81)58 (50 to 66)
PPV, % (95% CI)26 (13 to 43)17 (10 to 28)15 (4 to 34)20 (11 to 34)15 (8 to 25)
NPV, % (95% CI)97 (92 to 99)98 (94 to 100)94 (89 to 97)98 (94 to 100)99 (95 to 100)
Positive likelihood ratio4.122.422.143.142.22
Negative likelihood ratio0.400.210.820.290.12
Youden index0.50480.50830.15200.53570.5100
Flare within 3–6 months after treatment withdrawal
Sensitivity, % (95% CI)30 (12 to 54)45 (23 to 68)35 (15 to 59)55 (32 to 77)65 (41 to 85)
Specificity, % (95% CI)86 (79 to 91)65 (57 to 73)89 (83 to 94)79 (72 to 85)61 (53 to 69)
PPV, % (95% CI)21 (8 to 41)15 (7 to 26)30 (13 to 53)26 (14 to 41)18 (10 to 29)
NPV, % (95% CI)90 (84 to 95)90 (83 to 95)91 (86 to 95)93 (87 to 97)93 (86 to 97)
Positive likelihood ratio2.091.303.332.611.67
Negative likelihood ratio0.820.840.730.570.57
Youden index0.15620.10360.24470.33950.2618
Flare within 0–6 months after treatment withdrawal
Sensitivity, % (95% CI)46 (29 to 63)63 (45 to 79)32 (17 to 51)65 (46 to 80)76 (59 to 89)
Specificity, % (95% CI)86 (79 to 91)65 (57 to 73)89 (83 to 94)79 (72 to 85)61 (53 to 69)
PPV, % (95% CI)42 (26 to 59)29 (19 to 41)41 (22 to 61)41 (28 to 55)31 (21 to 42)
NPV, % (95% CI)87 (81 to 92)88 (81 to 94)86 (79 to 91)91 (85 to 95)92 (85 to 97)
Positive likelihood ratio3.181.813.073.071.97
Negative likelihood ratio0.630.570.760.450.38
Youden index0.31340.28220.21830.43650.3766
  • * The predicted outcome of the single biomarkers was set positive if the observed level was greater or equal than the reported cut-off level, respectively.

  • Some of the data on MRP8/14 have been previously reported.7

  • hsCRP, high-sensitivity C reactive protein; NPV, negative predictive value; PPV, positive predictive value.