Real life picture of the use of intravenous immunoglobulins in idiopathic inflammatory myopathies: Results of a multicentric study

Background: despite the absence of specific guidelines, the treatment with intravenous immunoglobulins (IvIg) is considered effective in patients with refractory idiopathic inflammatory myopathies (IIM). The aim of our study is to evaluate the effectiveness and the safety of IvIg and define the possible profile of IIM patients candidate to IvIg treatment. Methods: we performed a retrospective study of IIM pts. treated with IvIg (2 g/kg/month). We collected demographic, epidemiological, laboratory and clinical data. Additionally, to evaluate the toxicity, the adverse events occurred during the treatment were collected. Results: 123 patients with IIM were included in the study. The main indications for the prescription of IvIg were muscle (83.7% of patients) and esophageal involvement (45.5% of patients). IvIg were started mainly for refractory disease. At the end of treatment (mean duration 14 months), muscular necrosis enzymes decreased significantly and dysphagia VAS decreased significantly (p < 0.001), while MMT value increased (104.6 ± 24.2 vs. 127.0 ± 22.2 p < 0.001). Ninety-six pts. (78%) responded to IvIg. They had a shorter disease duration (p < 0.001), higher creatine kinase levels (p < 0.001), and higher prevalence of myalgias at the baseline (p = 0.023) compared to non-responders. The presence of Raynaud's phenomenon (p = 0.023–odds ratio 0.28 [0.11–0.72]) and skin involvement (p = 0.004, odds ratio 0.18 [0.06–0.55]), were associated to a worse response. Adverse events were mostly mild and transitory. Conclusions: Despite their high cost, IvIg confirmed their effectiveness in refractory IIM pts., particularly in muscular and esophageal manifestations. Specific clinical characteristics at the baseline may identify the patients with higher probability of response to the treatment.