Background/Purpose: Despite the absence of specific guidelines, the treatment with intravenous immunoglobulins (IvIg) is considered effective in patients with refractory idiopathic inflammatory myopathies (IIM). Recently, a new therapeutic approach with subcutaneous immunoglobulins (ScIg) has been proposed. The aim of our study is to evaluate efficacy and safety of ScIg in patients with IIM followed in a rheumatology unit.

Methods: 10 IIM patients (7 Female, mean age 64.4±10.2 years) treated in our rheumatology unit with ScIg were enrolled. Six patients had PM and 3 DM (Bohan and Peter criteria) while 1 had IBM (Griggs criteria). The treatment scheme was 2g/kg/month divided in 4 weekly administrations at home. At baseline and after treatment the following data were collected: myositis specific/associated autoantibodies; indications to the treatment (skin lesions, dysphagia, lung or muscular involvement) and clinical response according to the manual muscle test 8 (MMT8), creatinkinase (CK), physician and patients’ disease activity visual analogue scale (ph-VAS and pt-VAS), and health assessment questionnaires (HAQ).

Results:

Nine patients received ScIg after treatment with IvIg (mean 22 months of treatment) while one started ScIg directly for severe skin involvement. Five patients had Ro52 positivity, 1 Tif1γ, 1 anti-Ku.The indication for the treatment was the presence of refractory disease in 8 patients. All of these patients were treated with high dose steroids and at least 2 immunosuppressant. In 2 patients the treatment was prescribed for recurrent infections during immunosuppressive treatment. In addition, 7 patients had severe dysphagia. Only 1 patient reported an adverse event (vomiting, headache) and stopped the treatment after the first month. In the other nine patients, the duration of the follow-up was 18 months (3-72). At the last evaluation, compared to the switch to ScIg, no statistically significant differences were identified in MMT8, CK, ph-VAS, pt-VAS and HAQ (p=n.s.). The mean daily steroid dose was reduced from 6.1±4.2 to 3.7±2.5 mg (p=n.s.). Dysphagia improved in 4/7 patients. The patient who started ScIg directly for refractory and severe skin involvement improved after 6 months of treatment. No disease flares were identified during the treatment.

Conclusion: Despite their high cost, ScIg confirmed similar efficacy compared to IvIg for the treatment of refractory IIM patients and may represent an alternative. The treatment may allow an improvement of the quality of life of the patients, reducing the necessity of hospitalization. Furthermore was safe and no serious adverse events were reported during the treatment. Additional data with longer follow-up are necessary to confirm our data in different subset of patients.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/subcutaneous-intravenous-immunoglobulins-in-idiopathic-inflammatory-myopathies-analysis-of-a-monocentric-cohort/