Effect of plasma exchange and immunosuppressive medications on antibody titers and outcome in anti-complement factor H antibody-associated hemolytic uremic syndrome.

BACKGROUND

Anti-complement factor H (anti-CFH) antibody-associated hemolytic uremic syndrome (HUS) is an important cause of acute kidney injury in Indian children. While management comprises plasma exchange and immunosuppression, information on the impact on serial antibody titers and outcomes is limited.

METHODS

This retrospective study included 45 patients with anti-CFH-associated HUS who were followed for ≥12 months. Following the initial plasma exchange sessions, patients received prednisolone and either intravenous (IV) cyclophosphamide (n = 31) or IV rituximab (n = 14), followed by maintenance immunosuppression.

RESULTS

The median anti-CFH antibody titers fell from 3,215.5 [interquartile range (IQR) 1,977.9-8,453.9 to 414.6 (IQR 251.6-1,368.2) AU/ml with plasma exchange therapy (P < 0.0001), and the decline was similar with three, five, or seven plasma exchange sessions (P = 0.08). Serial anti-CFH titers were similar in patients receiving IV cyclophosphamide- and rituximab-based regimens during the 12-month follow-up (P = 0.63). Renal outcomes and relapse frequencies at the 15.4-month follow-up were comparable. Seven patients relapsed 6.5 (IQR 2.2-12.3) months from treatment onset. Patients with relapse had higher antibody titers during remission (P = 0.017). Titers of ≥1,300 AU/ml at 6 months predicted subsequent relapses.

CONCLUSIONS

Our patients with anti-CFH antibody-associated HUS showed a significant fall in antibody titers following daily plasma exchange sessions. Therapy with cyclophosphamide- or rituximab-based regimens was associated with similar outcomes and a comparable decline in antibody titers.