AB0675 Rheumatoid factor positivity is related to clinical and immunological characteristics in patients with eosinophilic granulomatosis with polyangiitis

Background Eosinophilic granulomatosis with polyangiitis (EGPA) is a rare antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV), which is characterised by vasculitis with allergic features such as asthma and eosinophilia. Although rheumatoid factor (RF) positivity is known to be as high as 37%–50% in AAV patients1 the clinical significance of RF-positivity remains unknown. Objectives To investigate clinical features in patients with RF in EGPA. Methods Consecutive patients who were diagnosed with EGPA between January 2008 and January 2018 in Keio University Hospital were enrolled. Clinical information were collected from medical records retrospectively. We divided patients into 2 groups according to RF positivity, and compared clinical features. Results Seventeen patients were enrolled in the study. The mean age was 57.4 years old, and 82% were female. Among them, 11 patients were RF positive (RF positive group) and 6 patients were negative (RF negative group). The female rate tended to be higher in the RF positive group than the negative group (82% vs 50%, p=0.087). While the Birmingham Vasculitis Activity Score was comparable between the two groups (21.5 vs 17.3, p=0.329), general symptoms (fever and weight loss) and gastrointestinal lesions were more frequent in the RF positive group (55% vs 17%, p=0.072; 45% vs 17%, p=0.137) and central nervous involvement was less frequent (18% vs 67%, p=0.024). No patient with negative RF presented with arthralgia/arthritis. The count of eosinophil and IgA levels at diagnosis were significantly higher in the RF positive group than the RF negative group (15704/μl vs 4751/μl, p=0.009; 238 mg/dL vs 162 mg/dL, p=0.048). Interestingly, ANCA positivity was negatively correlated with RF positivity. MPO-ANCA was positive in 27% of the RF positive group and in 66% of the RF negative group, and PR3-ANCA was positive in none of the RF positive group and 17% of the RF negative group. Double negative was more frequent in RF positive group (73% vs 33%, p=0.060). Conclusions RF positivity was associated with clinical and serological characteristics in patients with EGPA, suggesting different pathogenesis or immunological disturbances is related. Reference [1] Pagnoux C, Seror R, Berezne A, Rouabhia S, Goulvestre C, Guillevin L. Remittent non-destructive polysynovitis in P-ANCA-positive vasculitis patients with anti-CCP antibodies. Joint Bone Spine. 2010;77(6):604–7. Disclosure of Interest None declared