Background Raised levels of serum rheumatoid factors (RFs) of different immunoglobulin classes had been reported in a high proportion of patients with rheumatoid vasculitis. RF used to be studied and was shown elevated in some forms of vasculitides. Patients with antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) are often positive for RF. However, the clinical significance of RF has been seldom examined in AAV.
Objectives The aim of this study was to investigate association between the presence of RF and clinical features and outcomes in AAV.
Methods Eighty-one patients were diagnosed with AAV from 2006 to 2015 in our hospital. Among 81 patients, forty-seven patients (17 males, median age 67 years) who were not complicated with rheumatoid arthritis and in whom RF was measured before the treatment, were studied, retrospectively. Patients were classified using the European Medicines Agency vasculitis classification algorithm. AAV included eosinophilic granulomatosis with polyangitis (n=10), granulomatosis with polyangitis (n=14), microscopic polyangitis (n=16) and unclassifiable vasculitis (UV) (n=7). Patients with UV with MPO-ANCA or PR3-ANCA were included in this study. IgM-RF was measured using a latex agglutination assay. Disease activity was assessed with Birmingham vasculitis activity score (BVAS). IgM-RF, C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), serum ferritin, IgG, IgM, IgA, MPO-ANCA and PR3-ANCA were obtained from hospital records. Clinical manifestations between RF-positive subset (n=29) and RF-negative subset (n=18) were analyzed using Fisher's exact and Wilcoxon rank sum tests. Correlation coefficients were established with Spearman's correlation coefficient. Data were shown as medians (interquartile range).
Results BVAS was higher (14 (12–22) vs 12 (6–16), P=0.026) in the RF-positive subset than the RF-negative subset. CRP and ESR were higher (P=0.020 and 0.007, respectively) in the RF-positive patients. IgM-RF titers significantly correlated with BVAS (r=0.50, P=0.0004). In addition, CRP, ESR, IgM and IgG also had a significant correlation with IgM-RF titers. The frequency of initiation of dialysis therapy (14% vs 6%), usage of mechanical ventilation (14% vs 0%) and mortality (10% vs 0%) were higher in the RF-positive subset than in the RF-negative subset although no significant differences were shown.
Conclusions In AAV, IgM-RF titers are significantly correlated with disease activity and inflammatory markers. Presence of RF could be a poor prognostic factor in patients with AAV.
Watts R, Lane S, Hanslik T, et al. Development and validation of a consensus methodology for the classification of the ANCA-associated vasculitides and polyarteritis nodosa for epidemiological studies. Ann Rheum Dis 2007;66:222–227.
Westedt ML, Herbrink P, Molenaar JL, et al., Rheumatoid factors in rheumatoid arthritis and vasculitis. Rheumatol Int 1985;5:209–14.
Kronbichler A, Kerschbaum J, Gründlinger G, et al. Evaluation and validation of biomarkers in granulomatosis with polyangiitis and microscopic polyangiitis. Nephrol Dial Transplant 2016;31(6):930–6.
Disclosure of Interest None declared