Long-term subcutaneous immunoglobulin use in inflammatory myopathies: A retrospective review of 19 cases.

Subcutaneous immunoglobulin (SCIg) therapy is indicated in primary and secondary immunodeficiency diseases. Its use in practice is being extended to autoimmune diseases. Few studies investigated the feasibility and safety of SCIg in these rare conditions. The aim was to describe the use of SCIg in inflammatory myopathies including polymyositis (PM), dermatomyositis (DM) and inclusion body myositis (IBM), in real-life settings. This case series was based upon a retrospective data collection. The primary objective was to assess the feasibility of the SCIg injections for the treatment of autoimmune diseases and adherence to high doses. Secondary objectives included safety and efficacy. Nineteen cases were identified: 7 patients were diagnosed with PM, 7 with IBM, 2 with DM, and 3 with myositis associated with connective tissue disease. Patients were treated and followed-up for a mean duration of 18.8 months (range 4.5-42). They received a median of 64 SCIg infusions and a total of 1215 infusions. Out of 14 patients, 10 showed an improvement in muscle strength, and 7 out of 11 showed an improvement in muscle disability scale. Two patients were lost to follow-up. Few slight adverse reactions were reported including mainly mild headaches and local skin reactions. Any serious adverse event was reported. These results suggest that the use of high-dose SCIg is feasible, beneficial and safe in patients with inflammatory myopathies. SCIg could be an alternative of IVIg in patients with difficult venous access or with insufficient response, and in patients preferring home care setting.