271. SEVERE INFECTIONS IN PATIENTS WITH ANCA-ASSOCIATED VASCULITIS TREATED WITH RITUXIMAB

Abstract

Background and objectives Rituximab (RTX) is an anti-CD20 antibody that selectively depletes B-cells and has emerged as a therapy for ANCA-associated vasculitis (AAV) during the past decade. This study sought to quantify, and determine potential risk factors for, severe infections in AAV patients treated with RTX at rheumatology clinics in Mexico City, Mexico and Lund, Sweden. Methods The study consisted of a retrospective case-record review (2005-2015) with standardized data collection related to the occurrence of severe infection in 46 patients with AAV in Mexico City (n = 20) and Lund (n = 26) treated with RTX during their disease course. Median duration of follow-up from first RTX dose to death or end of study was 26 months. Results Eleven (24%) patients suffered a total of 18 severe infections (infection rate of 11.5/100 patient-years). Thirteen of the 18 infections (72%) occurred within the first year of treatment. Risk factors for severe infection were older age at RTX initiation and absence of ENT-involvement at diagnosis. In multivariate analyses, age at RTX infusion was the only independent factor predicting severe infection. Four patients (9%) died during follow-up, all as a result of infection. Conclusions Severe infections are common following RTX treatment, and mortality due to infection is a major concern. Most severe infections occur within the first year of RTX treatment. The negative correlation of ENT involvement with severe infection might reflect GPA phenotype heterogeneity. Older age at time of RTX treatment independently predicts severe infections.