B-CELL ACTIVATING FACTOR AS A BIOMARKER OF ACTIVITY OF SYSTEMIC NECROTIZING VASCULITIS (SNV)

Background: Non-specific marker of inflammation such as C-reactive protein (CRP) and the erythrocyte sedimentation rate (ESR) have limited value in assessment of vasculitis activity. Normal ESR values do not exclude the diagnosis of active vasculitis, and its increase may be due to concomitant infection. Objectives: To evaluate the levels of B-cell activating factor and ESR in pts with different activity of SNV. Methods: The serum levels of B-cell activating factor (BAFF) and ESR were measured in 48 pts with SNV (granulomatosis with polyangiitis – 22, eosinophilic granulomatosis with polyangiitis – 9, microscopic polyangiitis – 6, polyarteritis nodosa – 11). The 48 pts included 18 male and 30 female with median age 49; 24 were positive for cytoplasmic antineutrophil cytoplasmic antibodies and 11 for perinuclear antineutrophil cytoplasmic antibodies. At screening, 9 pts were without any treatment, 26 pts were receiving glucocorticoids (GCs) and 13 pts were receiving some cytotoxic agents and GCs. Clinical activities of pts were calculated by the Birmingham Vasculitis Activity Score (BVAS). All pts were divided into 3 groups according to the value of BVAS: group 1 (BVAS≤11; n=12), group 2 (BVAS =12–23; n=23) and group 3 (BVAS≥24; n=13). The outcomes of this study were the differences in marker levels between groups estimated by analysis of the absolute changes in marker levels and the areas under receiver operating characteristic (ROC) curves. Results: The levels of BAFF were significantly higher in group 3 (0.88±0.19 ng/ml) compared with group 1 (0.68±0.13 ng/ml, p<0.05), but did not distinguish from the group 2 (0.90±0.35). There were not significant differences in ESR between groups. ROC analysis indicated that the AUC for ESR is 0.63±0.10 (p=0.17) and for BAFF – 0.72±0.12 (p<0.05), which indicates fair capacity for BAFF differentiate groups of pts with low activity or remission of SNV and pts with severe SNV (sensitivity - 61.5%, specificity - 88.9%), while it was poor for ESR (sensitivity - 85.7%, specificity - 46.4%). Conclusions: There are significant differences in levels of BAFF between pts with BVAS≥24 and pts with BVAS≤11. According to ROC analysis evaluation of serum BAFF level distinguishes pts with active SNV from pts with low activity or remission better than determination of ESR. Disclosure of Interest: None declared DOI: 10.1136/annrheumdis-2017-eular.2200Citation: Annals of the Rheumatic Diseases, volume 76, supplement 2, year 2017, page 615Session: Vasculitis (Poster Presentations )