Kidney Transplantation in Childhood-Onset ANCA-Associated Vasculitis

KEY POINTS: Among 72 patients with childhood-onset ANCA-associated vasculitis, kidney transplant survival was good (86%). ANCA-associated vasculitis relapse occurred in 8 patients (11%), a median of 71 months after transplantation and resulted in graft failure in only one case. Positive ANCA at the time of transplantation did not predict graft failure but was associated with a higher risk of relapse and worse graft function. BACKGROUND: 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 multicenter 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 per 1.73 m 2 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 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 (interquartile range, 25-97), 70 patients (97%) were alive, 62 (86%) had a functioning graft, 28 (39%) had developed chronic graft dysfunction, and 8 (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 (hazard ratio [HR], 12.11; 95% confidence interval [CI], 1.19 to 122.49). Positive ANCA at the time of transplantation was significantly associated with a chronic graft dysfunction (HR, 4.16; 95% CI, 1.71 to 10.13) and AAV relapse (HR, 23.1; 95% CI, 2.67 to 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.