Evaluating Renal Disease in Pediatric-Onset Antineutrophil Cytoplasmic Antibody-Associated Vasculitis: Disease Course, Outcomes, and Predictors of Outcome.

Objective: We aimed to study the disease course, outcomes, and predictors of outcome in pediatric-onset antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) affecting the kidneys.

Methods: Patients eligible for this study had a diagnosis of granulomatosis with polyangiitis (GPA), microscopic polyangiitis, or ANCA-positive pauci-immune glomerulonephritis, were 18 years or younger at diagnosis, had renal disease defined by biopsy or dialysis dependence, and had clinical data at diagnosis and at either 12 or 24 months. Ambispective data from A Registry for Children with Vasculitis/Pediatric Vasculitis Initiative Registry was used. The primary outcome was inactive renal disease (pediatric vasculitis activity score = 0 or 1) at 12 months. Secondary outcomes included rates of improved renal function and damage within 24 months. Renal function, defined by estimated glomerular filtration rate, was categorized into Kidney Disease Improving Global Outcomes (KDIGO) stages at diagnosis and tested as a predictor of outcome using a proportional-odds logistic regression model.

Results: A total of 145 patients were included: 68% were female, and 78% had GPA. At 12 months, 83% of patients achieved inactive renal disease; however, 42% had evidence of permanent renal damage. Compared with patients with normal renal function at diagnosis, patients with moderate to severely reduced renal function, or kidney failure at diagnosis, had an odds ratio of 8.62 (P = 0.002; 95% confidence interval [CI] 2.31-32.1) and 26.3 (P < 0.001; 95% CI 6.32-109), respectively, for being in a non-normal KDIGO category at 12 months.

Conclusion: The majority of patients with pediatric AAV achieve inactive renal disease by 12 months; however, almost half have evidence of damage. Renal function at diagnosis is a strong predictor of renal function at 12 months.