Purpose: Polymyositis and dermatomyositis are inflammatory muscular diseases of unknown cause. Many interventions are available to treat patients with these conditions including corticosteroids, immunosuppressive drugs, plasmapheresis, and total body irradiation. However, these therapies are not always effective, and they may be associated with certain serious side effects. An attempt was made to evaluate the efficacy of polyvalent intravenous immunoglobulin (IVIG) in patients with polymyositis or dermatomyositis refractory to traditional treatment.
Patients and methods: Twenty patients (16 women and 4 men; mean age 43 [16 SD] years), 14 with chronic refractory polymyositis and six with dermatomyositis, received high doses of IVIG because of the failure of traditional treatments (prednisone [19], methotrexate [10], azathioprine [6], cyclophosphamide [3], cyclosporine [3], chlorambucil [1], plasmapheresis [8], lymphopheresis [1], and total body irradiation [1]). In one patient with positive results on picornavirus serologic testing, IVIG was the first treatment choice. IVIG therapy was given with prednisone in 15 patients, with methotrexate in six patients, and with plasmapheresis in one patient. There were no changes in treatment in the 2 months before the introduction of IVIG therapy and no increases in dose during this treatment. Preparations of polyvalent human intravenous gammaglobulins with increased intact immunoglobulin G were used. Thirteen patients received 1 g/kg daily for 2 days each month, and seven patients received 0.4 g/kg daily for 5 days each month. The mean duration of treatment was 4 months.
Results: Clinical assessment, which consisted of the measurement of proximal muscle power, and biochemical studies were carried out before each treatment period. Significant clinical improvement was noted in 15 of the 20 patients. Mean muscle power estimated for the 20 patients before and after IVIG therapy was statistically significantly reduced (p less than 0.01). Eighteen patients showed biochemical improvement, and two patients with normal initial serum creatine kinase levels showed clinical improvement. Mean creatine kinase levels for the 20 patients during IVIG therapy showed a statistically significant decrease from the first IVIG perfusions (p less than 0.01). Side effects of IVIG therapy were noted in four patients; however, these effects were mild. During IVIG therapy, steroid doses were significantly reduced from the second or the third IVIG infusion (p less than 0.05).
Conclusion: IVIG is an efficacious new therapy for polymyositis and dermatomyositis and should play a role in the treatment of these diseases, replacing or reducing steroid and immunosuppressive medications.