Prognostic Factors and Long-Term Outcome with ANCA-Associated Kidney Vasculitis in Childhood

Background and objectives. Anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis is extremely rare in children. We report the clinico-pathological features, long-term outcomes, and prognostic factors of a large paediatric cohort of patients with ANCA-associated kidney vasculitis. Design, setting, participants, and measurements. This retrospective study included 85 consecutive patients with kidney biopsy-proven ANCA-associated vasculitis followed at tertiary referral centres in Italy and Canada. Kidney biopsies were categorised as focal, crescentic, sclerotic or mixed following Berden's classification. The prognostic significance of baseline clinical, laboratory and histological findings was analysed with respect to kidney failure or chronic kidney disease (CKD) 3-5/kidney failure. Results. Fifty-three patients had microscopic polyangiitis (62%) and 32 granulomatosis with polyangiitis (38%). Rapidly progressive glomerulonephritis was the most frequent presentation (39%); one third of the patients also had nephrotic-range proteinuria. Kidney biopsies were classified as focal in 21% of the patients, crescentic in 51%, sclerotic in 15% and mixed in 13%. Remission-induction therapies included cyclophosphamide in 78% of cases. Twenty-five patients (29%) reached kidney failure. The median time to kidney failure or last follow-up was 35 months (6-89) in the whole cohort, and 73 months (24-109) among the patients who did not reach this outcome. Cases with sclerotic histology showed significantly shorter kidney survival [HR 11.80 (95% CI 2.49-55.99)] and CKD 3-5-free survival [HR 8.88 (95% CI 2.43-32.48)] as compared with focal/mixed ones. Baseline eGFR, low serum albumin, hypertension, central nervous system complications and sclerotic histology, which reflected severe kidney involvement, were associated with both kidney failure or CKD stage 3-5/kidney failure at unadjusted analysis; no independent prognostic factors emerged at multivariate analysis. Conclusions. Children with ANCA-associated kidney vasculitis often have aggressive presentation; one-third of them progress to kidney failure and usually do so early during the follow-up. A severe renal presentation is associated with the development of CKD or kidney failure.