Long-term outcome of pediatric anti-complement factor H antibody-associated atypical hemolytic uremic syndrome receiving abbreviated plasma exchange: a retrospective study from a single center

BACKGROUND: Anti-complement factor H antibody- (anti-CFH Ab) associated atypical hemolytic uremic syndrome (aHUS) is a known cause of pediatric complement-mediated thrombotic microangiopathy. In our center, plasma exchange (PEX) until remission paired with immunosuppression continues to be the mainstay of therapy, due to limited access to eculizumab. We wanted to study the long-term outcome of this cohort. METHODS: We conducted a retrospective cohort study of children (<12 years) with Anti-CFH Ab-associated aHUS admitted between January 2017 and December 2024 at our center. Clinical, laboratory, treatment, and outcome data were retrieved from medical records. The primary outcome was renal recovery, defined as eGFR >90 mL/min/1.73 m2 with normal blood pressure, no significant proteinuria, and absence of hematuria at last follow-up or at 5 years. RESULTS: Of 66 records screened, 40 children were eligible. Median age at presentation was 7 years (interquartile range [IQR] 5,8). Median anti-CFH Ab titer was 306 AU/mL (IQR 214-426). Low C3 was noted in 55% of subjects. All patients received PEX (median 11 cycles; IQR 7.25, 20) and immunosuppression. Median follow-up was 24 months (IQR 7-53). At last follow-up, 21 (52.5%) achieved complete renal recovery, while 19 (47.5%) had CKD stage 2-4. Relapse incidence was 7.1 per 100 person-years, usually within 6 months of onset. No baseline clinical, laboratory, or treatment variable except duration of dialysis independently predicted renal recovery. Persistent proteinuria was observed up to 6 months but subsequently improved. CONCLUSIONS: PEX paired with immunosuppression remains effective for anti-CFH Ab-associated aHUS, but further studies are needed to refine protocols and evaluate complement inhibitors for improved long-term outcomes.