Characteristics and Risk Factors of Severe infection in ANCA-associated vasculitis

Abstract Background : There is a close relationship between ANCA-associated vasculitis and infections. Based on a cohort of ANCA-associated vasculitis patients from East China, this study aimed todescribe the infection characteristics and prognosis of the patients, and explore the risk factors for severe infections. Methods : Relevant data from the cohort of ANCA-associated vasculitispatients (n=82) at the affiliated Huashan Hospital, Fudan University, collected between 2012 and 2021 was retrospectively reviewed to describe the basic characteristics and treatment response of the completely relieved vasculitis patients (n=63) and non-completely relieved AAV patients (n=19), and to compare the incidence of severe infections and prognosis between AAV patients with underlying infections (n=17) and those without infection(n=65). Results : 65% of the infections occurred within the first three months of AAV-induced treatment. The main site of common infection was the urinary system, with Escherichia coli being the most common pathogen. The main site of severe infections was the respiratory system, and the main pathogenic bacteria included Klebsiella pneumoniae, Candida albicans, and Aspergillus. The complete remission rate of patients with underlying infections before diagnosis of AAV was lower than that of patients without underlying infections before the onset of the disease (58.82% vs 81.84%, p=0.048), and even if the dose of immunosuppressants was reduced, the incidence of severe infections in patients with underlying infections was higher than that in patients without infections (63.64% vs 32.36%, p=0.0055). The presence of underlying infections at the time of diagnosis of AAV (HR=4.569, 95% CI=1.518-14.302, p=0.007), elevated ALT at the onset of the disease (HR=3.163, 95% CI=1.060-9.371, p=0.039), and the use of cyclophosphamide (HR=4.081, 95% CI=1.246-13.279, p=0.020) were found to be the risk factors for severe infections. Conclusions: Bacterial and fungal pneumonia are the main types of severe infection after ANCA-associated vasculitis immunosuppressive therapy. The presence of underlying infection and impaired liver and kidney function at the time of diagnosis of AAV are independent risk factors for severe infections in ANCA-associated vasculitis patients after receiving immunosuppressive therapy. Patients with underlying infection with AAV have a lower complete response rate and are still prone to severe infection after receiving reduced immunosuppressive therapy.