High‐dose intravenous immunoglobulin pulse therapy in patients with progressive immunoglobulin A nephropathy: a long‐term follow‐up

Summary In progressive immunoglobulin A nephropathy (IgAN), intravenous immunoglobulin (IVIg) treatment has been used to delay disease progression, but the long‐term efficacy is largely unknown. We report the clinical outcomes after IVIg therapy in six male patients with progressive IgAN [median glomerular filtration rate (GFR) 31 ml/min per 1·73 m 2 ] followed for a median observation period of 8 years. In this single‐arm, non‐randomized study, IVIg was given monthly at a dose of 2 g/kg body weight for 6 months. The course of renal function was assessed by linear regression analysis of GFR and proteinuria, and was compared to eight patients with IgAN (median GFR 29 ml/min per 1·73 m 2 ) without IVIg as a contemporaneous control group. IgAN disease progression was delayed after IVIg therapy on average for 3 years. The mean loss of renal function decreased from − 1·05 ml/min per month to − 0·15 ml/min per month ( P  = 0·024) and proteinuria decreased from 2·4 g/l to 1·0 g/l ( P  = 0·015). The primary end‐point (GFR < 10 ml/min or relapse) occurred 5·2 years (median; range 0·4–8·8) after the first IVIg pulse, and after 1·3 years (median; range 0·8–2·4) in the control group ( P  = 0·043). In Kaplan–Meier analysis, the median renal survival time with IVIg was prolonged by 3·5 years (IVIg 4·7 years versus control 1·2 years; P  = 0·006). IVIg pulse therapy may be considered as a treatment option to reduce the loss of renal function and improve proteinuria in patients with progressive IgAN.