361. A History of Autoimmune Disease is associated with fewer Relapses in patients with ANCA Vasculitis

Objectives: To explore the frequency and impact of an autoimmune disease past-medical history (PMH) in the clinical picture and outcomes of patients with antineutrophil cytoplasmic autoantibodies (ANCA) associated vasculitis (AAV). Patients and methods: This was a retrospective study of patients with biopsy-proven AAV, >16 years old, with detailed information about their PMH. Outcomes of interest included remission, treatment resistance, relapse, end-stage kidney disease (ESKD), and death. Results: 206 patients with biopsy-proven AAV and available information regarding their PMH were studied. 63(30.6%) of them had a history of autoimmune disease prior to AAV diagnosis. The mean age overall was 54.1 years. One huned and five patients (51%) were positive for PR3-ANCA, 101(49%) for MPO-ANCA. Granulomatosis with polyangiitis was diagnosed in 79(38.3%), microscopic polyangiitis in 97(47.1%) and renal-limited vasculitis in 30(14.6%) individuals. Remission rate was similar among patients with and without a PMH of autoimmune disease. Time-to-event analysis indicated that the relapse-free survival was significantly longer in patients with PMH of autoimmune disease (148.2 versus 61.9 months, p-value