Intravenous immunoglobulin for ANCA‐associated systemic vasculitis with persistent disease activity

Intravenous immunoglobulin (IVIg) is a potential alternative treatment for anti‐neutrophil cytoplasm antibody (ANCA)‐associated systemic vasculitis (AASV) with less toxicity than conventional immunosuppressive agents. This randomized, placebo‐controlled trial aimed to investigate the efficacy of a single course of IVIg (total dose 2 g/kg) in previously‐treated AASV with persistent disease activity in whom there was an intention to escalate therapy. Vasculitic activity was monitored by the Birmingham vasculitis activity score (BVAS), C‐reactive protein (CRP) and ANCA levels. Treatment response was defined as a reduction in BVAS of more than 50% after 3 months, and there was an intention to keep doses of concurrent immunosuppressive drugs unchanged during this period; follow‐up continued to 12 months. Seventeen patients were randomized to receive IVIg and 17 to receive placebo. Treatment responses were found in 14/17 and 6/17 of the IVIg and placebo groups, respectively ( p =0.015, OR 8.56, 95%CI 1.74–42.2). Following infusion of trial medication, greater falls in CRP were seen at 2 weeks ( p =0.02) and 1 month ( p =0.04) in the IVIg group. No differences were observed between ANCA levels or cumulative exposure to immunosuppressive drugs, and after 3 months there were no differences in CRP levels or disease activity between the IVIg and placebo groups. Seventeen adverse effects occurred after IVIg and six after placebo: they were mostly mild, although reversible rises in serum creatinine occurred in four from the IVIg group. A single course of IVIg reduced disease activity in persistent AASV, but this effect was not maintained beyond 3 months; mild, reversible side‐effects following IVIg were frequent. IVIg is an alternative treatment for AASV with persistent disease activity after standard therapy.