328 Immunosuppressive therapies in children with biopsy-proven iga vasculitis nephritis: a tertiary centre experience

Background IgA Vasculitis Nephritis (IgAVN) can lead to severe presentation including nephrotic syndrome. Data pertaining to the treatment outcomes of IgAVN with persistent moderate or nephrotic range proteinuria in children are, however, limited. Objectives The aim of this study is to determine the response to immunosuppressive therapies in this patient population. Methods We conducted a retrospective review on all children presenting with IgAV before 18 years between January 2009 and December 2019 in the Paediatric Nephrology Centre in Hong Kong. Patients with biopsy-proven IgAVN developing persistent moderate or severe nephrotic-range proteinuria despite ACE-inhibitor (ACEi), and followed for 24 months or more were included. Patient demographics, clinical and laboratory data, therapies received, and treatment outcomes were evaluated. Results Of the 177 patients with IgAV, 42 children developed proteinuria. 21 Chinese patients (76% boy) had persistent proteinuria despite ACEi and kidney biopsy confirmed IgAVN at a median age of 8.5 years (IQR 5.8–11.2). At baseline, 3 (14%), 14 (66%), 3 (14%) and 1 (4%) patients had moderate proteinuria, nephrotic-range proteinuria, nephrotic syndrome and nephritic-nephrotic syndrome, respectively. All patients had normal kidney function, except one child with an estimated GFR of 31 ml/min/1.73 m2. Median urine protein to urine creatinine ratio (UPCR) was 4.4 mg/mg (IQR 2.4–9.0) and serum albumin was 32 g/L (IQR 28–33.5). Histological findings were classified according to International Study of Kidney Diseases in Children (ISKDC): Class II (n=5, 24%), Class IIIa (n=9, 42%), Class IIIb (n=6, 29%), Class IV (n=1, 5%). All patients received corticosteroid at a median time of 33 days (IQR 12–52) since kidney involvement. Whereas 7 children (33%) with severe disease received monthly intravenous cyclophosphamide as induction therapy, 12 patients (57%) and 2 patients (10%) received calcineurin inhibitors and azathioprine, respectively. The maintenance therapy consisted of corticosteroid and one additional immunosuppression, including calcineurin inhibitors (n=16, 76%), azathioprine (n=4, 19%) and mycophenolate mofetil (n=1, 5%). Over a median follow-up period of 3.6 years (IQR 2.8–5.6), 18 patients (86%) attained complete remission at a median of 139.5 days (IQR 102–225) since immunosuppressants initiation. The other 3 patients achieved partial remission. Three patients (14%) relapsed in 7.5 months (IQR 1.2–16.2) following complete remission but resolved promptly with treatments. At last follow-up, all patients had normal kidney function and the median UPCR was 0.11 mg/mg (IQR 0.10–0.16). Conclusions Immunosuppressive therapies were associated with favourable renal outcomes in children with biopsy-proven IgAVN presented with persistent moderate or nephrotic range proteinuria despite ACEi. Further studies are required to determine the optimal treatments in this patient population.