Assessment of renal function in patients with myositis and treated with subcutaneous immunoglobulin: a series of 24 cases.

Immunoglobulin (Ig) therapy is used to treat a wide range of immunodeficiencies and autoimmune diseases; While, its clinical benefit has been demonstrated in several studies, Ig therapy is associated with a risk of systemic adverse effects. As such, Onset of renal impairment, including acute renal failure, osmotic nephrosis and renal insufficiency, after immunoglobulin administration is rare, but is one of the most significant concerns related to intravenous Ig use at immunomodulatory doses. However, only few studies have investigated the safety of subcutaneous Ig (SCIg) in relation to these rare conditions. The aim of this prospective study is to describe the safety of SCIg (Gammanorm), specifically with regards to renal function, in inflammatory myopathies including mainly polymyositis (PM), dermatomyositis (DM) and inclusion body myositis (IBM). Twenty-four cases were included: 10 patients with PM, 6 with IBM, 5 with DM, 2 with mixed connective-tissue disease (MCTD) and 1 patient with scleromyositis. SCIg was given two to three times per week at 2 g/kg/month in all patients. Patients were treated for a mean duration of 24.6 ± 11.4 months (range 8-37 months) and received a median of 78 SCIg infusions. Renal function was stable over the study period in all patients. High-dose SCIg was well tolerated; the treatment was not withdrawn during the first year in any patient for safety issues. These results suggest that the use of high-dose SCIg is generally feasible and safe in patients with inflammatory myopathies.