ARTHRITIS IN ADULT IGA VASCULITIS

Background: Arthritis is one of the main clinical features of IgA vasculitis (IgAV). Joint involvement represents the second most common manifestation in childhood IgAV with the predilection for the knees and ankles. Objectives: We aimed to describe the characteristics of arthritis in adult IgAV cohort. Methods: We analysed medical records of histologically proven adult IgAV cases, diagnosed between January 2010 and December 2020 at our secondary/tertiary rheumatology centre. The frequency, temporal occurrence and the localization of arthritis was recorded. In addition, we searched for potential differences in other IgAV features between patients with and without arthritis. Results: During the 132-month observation period we identified 328 new IgAV cases (59.5% males, median (IQR) age 64.3 (45.1; 76.1) years). Forty-eight (14.6%) patients developed arthritis. Arthritis was the first IgAV manifestation in 16 (4.9%) patients. Arthritis was mono-, oligo- and poly- articular (involving up to 15 joints) in 13 (4.0%), 25 (7.6%) and 10 (3.0%) patients, respectively. Arthritis was most common in wrists and ankles (each in 18 (37.5%) patients); metacarpophalangeal joints and knees (each in 11 (22.9%)); proximal interphalangeal joints (9 (18.8%)); elbows (8 (16.7%)) and metatarsophalangeal joints (4 (8.3%)). Clinical differences between IgAV patients with and without arthritis are presented in table 1 . Patients with arthritis were significantly younger, more commonly developed gastrointestinal tract involvement compared to those without arthritis. Arthritis remitted in all with immunomodulatory treatment (given predominantly for necrotic skin purpura or visceral involvement). Follow up (FU) data accessible for 42/48 (87.5%) patients with arthritis showed that IgAV relapsed in 10 (23.8%) patients during a median (IQR) 24.5 (12.9; 40.7) month FU. Relapses were limited to skin and/or kidneys, there were no relapses of arthritis. Table 1. Clinical characteristics of IgA vasculitis patients with and without arthritis Clinical characteristics Arthritis IgAV (48) Non-arthritis IgAV (280) P value Male gender (%) 56.3 60.0 0.636 Age (years)* 49.9 (36.1-66.9) 65.4 (48.4;77.5) <0.001 Ever smoker (%) 50.0 43.6 0.435 Prior infection (%) 43.8 30.4 0.094 Generalized purpura 50.0 50.0 1.0 Skin necroses (%) 35.4 49.6 0.085 GI involvement (%) 47.9 25.0 0.002 Renal involvement (%) 47.9 46.8 1.0 Elevated serum IgA (%) 33.3 (11/33) 52.0 (115/221) 0.061 Legend: * median and IQR; GI gastrointestinal; Conclusion: Arthritis in adult IgAV was frequently oligoarticular, involved large and small joints of both upper and lower extremities, and was not prone to chronic course and recurrence. In addition, we found an association between arthritis and gastrointestinal tract involvement. Disclosure of Interests: None declared Citation: Ann Rheum Dis, volume 80, supplement 1, year 2021, page 664Session: Vasculitis – small vessel vasculitis (POSTERS only)