Efficacy of high-dose intravenous immunoglobulin therapy in Japanese patients with steroid-resistant polymyositis and dermatomyositis

Intravenous immunoglobulin (IVIG) therapy was administered to 15 patients who were refractory to traditional steroid therapy [eight with polymyosis (PM), seven with dermamyosis (DM)] to evaluate its efficacy. Serum creatine kinase (CK) significantly decreased from week 1, and manual muscle test scores (MMT) and activities of daily living (ADL) significantly increased from week 2. Efficacy rates were 93.3% (14/15 patients) as assessed using the MMT score, 80.0% (12/15 patients) using the ADL score, and 100% (15/15 patients) using the serum CK level. When changes in the serum CK level over two four-week periods, one before IVIG therapy (from week −4 to week 0) and one after IVIG therapy (from week 0 to week 4), were transformed to natural logarithms, the four-week change after IVIG therapy was significantly greater than that before IVIG therapy. The estimated duration of the serum CK level remaining normal in 50% of the patients after IVIG therapy was 334.5 days. Adverse reactions were observed in seven of 16 patients (43.8%) during the study period, but none of the adverse reactions were considered to be serious or required emergency treatment. In conclusion, the present study indicates that IVIG therapy is effective for steroid-resistant PM/DM.