Infectious complications of ANCA-associated vasculitis: Description and associated outcome.

Abstract

In ANCA-associated vasculitis (AAV), both the disease and its treatments contribute to systemic complications, among which, infections represent a major cause of morbidity and mortality. This study aimed to evaluate the prevalence and prognosis of infectious complications in AAV, to identify associated risk factors, and to describe long-term outcomes. This retrospective monocentric study included patients followed in the Nephrology and Internal Medicine departments at Conception Hospital after a first episode or relapse of AAV between 2004 and 2024. Infection was considered if requiring hospitalization or an anti-infectious therapy. Follow-up was conducted until January 1^st, 2025. Among 264 patients included, the incidence of infection was 43.9%, with respiratory infections accounting for 49.1% of cases and bacterial infections for 75.3%, mainly with gram negative bacillus. Infection episodes were significantly associated with age >65 years (p =0.02), hypertension (p=0.04), diabetes (p =0.01), a high Five-Factor Score (p =0.005), a high BVAS (p =0.03), anti-PR3 positivity (p =0.03), acute kidney injury (p=0.004), cyclophosphamide (p =0.05), and intravenous corticosteroid for induction (p =0.03). In multivariate analysis, anti-PR3 positivity (aOR = 2.0, p=0.03) was independent risk factors, whereas methotrexate appeared protective (aOR = 0.08, p=0.001). Infections were independently linked to vasculitis relapses (aOR = 2.8, p=0.007) and cardiovascular events (aOR 3.0, p =0.01). Survival analysis demonstrated a significant association between mortality and infection (HR 2.14 _95%CI[1.59-2.91], p<0.001). Infections are frequent complications in AAV, and exert an independent impact on mortality. Anti-PR3 positivity increases infection risk, whereas methotrexate appears protective.