Table 3:

Discriminant power of individual and combined biomarkers as measured by AUC

	Group 1 vs Group 3
Biomarker	N	AUC (95% CI)	Sensitivity, Specificity
COL3A1	88	0.687 (0.571, 0.79)	(0.917, 0.425)
COMP	87	0.569 (0.443-0.694)	(0.766, 0.425)
PGA	88	0.481 (0.365, 0.587)	(0.688, 0.325)
ESR	82	0.574 (0.44, 0.693)	(0.822, 0.351)
CRP	70	0.624 (0.485, 0.757)	(0.278, 1)
anti-CSF2	87	0.686 (0.569, 0.792)	(0.787, 0.55)
IgA ASCA	84	0.618 (0.495, 0.74)	(0.479, 0.806)
IgG ASCA	84	0.569 (0.437, 0.692)	(0.333, 0.889)
OmpC	84	0.651 (0.531, 0.766)	(0.688, 0.611)
CBir	84	0.658 (0.534, 0.771)	(0.375, 0.889)
ANCA	84	0.611 (0.482, 0.728)	(0.771, 0.444)
COL3A1 (≥1039)* + anti-CSF2 (≥1.6)*	87	0.801 (0.713, 0.889)	(0.702, 0.825)

^*The cutoff of COL3A1 is based on the CART model. The cutoffs for other serology markers are the ones to define positivity in RISK study. This model is compared with the univariate COL3A1 (p=0.12) and anti-CSF2 (p=0.035) using DeLong's test for comparing two correlated ROC curves (Elisabeth R. DeLong, David M. DeLong and Daniel L. Clarke-Pearson“Comparing the areas under two or more correlated receiver operating characteristic curves: a nonparametric approach”. Biometrics 1988, 44, 837–845).

COL3A1 = collagen type III alpha 1 chain, COMP = cartilage oligomeric matrix protein, PGA = Physician Global Assessment, ESR = erythrocyte sedimentation rate, CRP = C-reactive protein, Anti-CSF2 = autoantibodies against colony stimulating factor 2, ASCA = anti- Socchoromyces cerevisiae antibodies, OmpC = antiouter membrane protein C precursor, CBir = anti-flagellin, ANCA = perinuclear anti-neutrophil cytoplasmic antibodies