Table 2.

Classical markers and IL-26 performance for active SLE identification (SLEDAI > 4).

	Sensitivity	Specificity	PPV	NPV
Anti-nuclear antibodies (≥ 1/200)	90% [55-100]*	28% [20-38] ***	11% [05-20] ***	97% [82-100] *
Anti-DNA antibodies (Farr) (positivity)	70% [35-93] **	69% [59-78] ***	18% [08-34] ***	96% [88-99] **
Anti-DNA antibodies (ELISA) (positivity)	40% [12-74] **	62% [51-71] ***	10% [03-23] ***	91% [82-97] **
C3 levels (below normal range)	10% [00-45] **	93% [86-97] ***	12% [00-53] ***	91% [84-96] **
C4 levels (below normal range)	30% [07-65] **	77% [67-85] ***	12% [02-30] ***	92% [83-97] **
IL-26 (above “high” threshold)	100% [69-100] **	89% [81-94] ***	48% [26-70] ***	100% [96-100] **

P-values of the comparison of sensitivities, specificities, PPV and NPV for each classical marker (versus IL-26) are depicted by stars (* < 0.05, ** < 0.01, *** < 0.001).

PPV, positive predictive value; NPV, negative predictive value.