LAUSR

OBJECTIVE Aging may be a risk factor for morbidity in anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV). We compared the rate and better characterized the type of disease- and treatment-related complications affecting young and elderly patients with AAV. METHODS All new cases of granulomatosis with polyangiitis or microscopic polyangiitis diagnosed in three referral centers between 2000-2016 were included. Patients were stratified by age into young or elderly (< or ≥65 years old, respectively). Data were collected from diagnosis until end of follow-up, with scheduled annual visits or additional visits in case of relapse or complication requiring hospitalization. RESULTS Of 141 patients included, 42 were elderly and 99 were young at the time of AAV diagnosis. Median follow-up was 58.0 [25-75% IQR, 31.0-60.0] months in young and 48.0 [23.25-60.0] months in elderly patients (p>0.05). Overall, the elderly group was associated to higher damage accrual assessed by Vasculitis Damage Index during follow-up (β=0.28, p<0.05). Sixty-three (44.7%) patients had acute kidney injury due to AAV-glomerulonephritis at diagnosis. In contrast to elderly, young patients showed significant improvement in renal function over time, particularly in the first 6 months while on induction treatment (ΔeGFR, median [25-75%IQR], 5.3 [0.4-14] versus 22.8 [5.9-52.1] ml/min/1.73m2, p=0.008), without significant changes after ANCA type stratification. Despite similar immunosuppressive therapy approaches and relapse rates, elderly patients had a higher rate of severe infections compared to younger patients (HR 2.1, 95% CIs: 1.1-4.4, p=0.043). CONCLUSIONS Elderly patients with AAV had higher susceptibility to disease- and treatment-related morbidity than younger patients, particularly to renal and infective morbidity.