Evaluating renal disease in pediatric-onset anti-neutrophil cytoplasmic antibody-associated vasculitis: disease course, outcomes, and predictors of outcome.

Objectives: We aimed to study the disease course, outcomes, and predictors of outcome in pediatric-onset anti-neutrophil 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 (MPA), or ANCA positive pauci-immune glomerulonephritis, were ≤ 18 years at diagnosis, had renal disease defined by biopsy or dialysis dependence, and had clinical data at diagnosis and either 12- or 24-months. Ambispective data from the ARChiVE/PedVas Registry was used. The primary outcome was inactive renal disease (PVAS = 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 (eGFR), was categorized into KDIGO (Kidney Disease Improving Global Outcomes) stages at diagnosis and tested as a predictor of outcome using a proportional odds logistic regression model.

Results: 145 patients were included. 68% were female, 78% had GPA. At 12-months, 83% of patients achieved inactive renal disease; however, 42% had evidence of permanent renal damage. Compared to 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% CI: 2.31, 32.1) and 26.3 (p <0.001, 95% CI: 6.32, 109), respectively, for being in a worse KDIGO category at 12-months.

Conclusion: The majority of pediatric-AAV patients 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.