Disease and treatment-related morbidity in young and elderly patients with granulomatosis with polyangiitis and microscopic polyangiitis

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.