Kidney Transplantation in Childhood-Onset Anti-Neutrophil Cytoplasmic Antibody-Associated Vasculitis: Long-Term Outcomes and Prognostic Factors

BACKGROUND: Anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) is rare in children, and results in kidney failure in up to one third of cases. There is very limited knowledge on kidney transplantation in childhood-onset AAV. We assessed kidney transplantation outcomes and prognostic factors in a multicentre cohort of patients with childhood-onset AAV. METHODS: Patients diagnosed with AAV during childhood (≤18 years) who received a kidney transplant were included in this retrospective study. We determined patient and graft survival, rates of chronic graft dysfunction (defined as eGFR<60 mL/min/1.73 m2 for ≥3 months) and AAV relapse, and assessed determinants of outcome with logistic regression models. Patients were matched 1:2 for age, sex, and era of transplantation with non-AAV recipients from The Hospital for Sick Children in Toronto, Canada, and their graft survival was compared. RESULTS: We included 72 patients, of whom 53 (74%) had microscopic polyangiitis and 19 (26%) granulomatosis with polyangiitis. Their median age (interquartile range, IQR) at the time of diagnosis and transplantation was 12 (9-14) and 14 (12-16) years, respectively. After a median post-transplant follow-up of 53 months (IQR 25-97), 70 patients (97%) were alive, 62 (86%) had a functioning graft, 28 (39%) had developed chronic graft dysfunction, and eight (11%) had experienced AAV relapse. Graft survival was comparable between AAV and non-AAV recipients. Acute rejection was the only independent predictor of graft failure (HR 12.11, 95% CI 1.19-122.49). Positive ANCA at the time of transplantation was significantly associated with a chronic graft dysfunction (HR 4.16, 95% CI 1.71-10.13) and AAV relapse (HR 23.1, 95% CI 2.67-200.28). CONCLUSIONS: Patients with childhood-onset AAV show good overall and graft survival after kidney transplantation and a low rate of post-transplant relapse. Further studies are warranted to confirm whether positive ANCA at the time of transplantation is associated with poorer graft outcomes.