Severe Polymyositis Improved By Intravenous Immunoglobulin Infusions

A DGReview of: "Results and long-term followup of intravenous immunoglobulin infusions in chronic, refractory polymyositis: An open study with thirty-five adult patients"

Arthritis & Rheumatism
02/26/2002 ~ By Anne MacLennan

Seventy percent of patients with chronic refractory polymyositis improve following receiving treatment with intravenous immunoglobulin infusions.

Furthermore, efficacy remains stable in 50 percent of these patients for at least three years after discontinuation of the therapy. These are the findings of a long-term open study of treatment with intravenous immunoglobulin infusions (IVIG) in 35 adult patients with chronic, refractory polymyositis. P. Cherin and colleagues from the Hôpital Pitié-Salpêtrière, Paris, France did this work.

Polymyositis is a rare inflammatory muscular disease of unknown cause. Corticosteroids and immunosuppressive drugs are the first choice of therapy, but they are not always effective and may cause serious side effects. Because many studies indicate polyvalent IVIG is of interest for treating dermatomyositis, these researchers sought to evaluate efficacy and benefits over time of IVIG in patients with polymyositis refractory to traditional treatments. Twenty of the 35 patients were female and 15 were male. All were white, average age was in the early 40s.

All were treated with high doses of IVIG after traditional treatments. These included prednisone (35 patients), methotrexate (24), azathioprine (13) azathioprine, cyclophosphamide (four), cyclosporine (seven), chlorambucil (one), plasmapheresis (eight), lymphopheresis (one) and total body irradiation (one).

In the two months before initiation of IVIG therapy, there had been no changes in the patients' treatment, and doses were not increased during IVIG treatment.

Preparations of polyvalent human IVIG with increased concentrations of intact IgG were used in the study, and patients received 1 gm/kg/day for two consecutive days per month. Mean course of treatment was four to six months.

Clinical assessment involved evaluation of proximal muscle power, muscle disability scale score and oesophageal disorders; biochemical evaluations done before each treatment period were compared by Student's t-test and nonparametric Wilcoxon test.

Twenty-five of the patients (71.4 percent) showed significant clinical improvement in the short term. Mean muscle power, which was estimated before and after IVIG therapy, significantly improved. All patients had a significant biochemical response, with mean creatine kinase levels during IVIG therapy decreasing significantly before the fourth IVIG perfusion. Side effects were noted in six patients and were usually minor.

Initial prednisone dose was able to be reduced by more than 50 percent in all patients. Mean follow-up time for the 25 patients who responded favourably to IVIG treatment was 51.4 ± 13.1 months. Twelve of these 25 patients remained in full remission following the initial course of IVIG, resulting in complete stoppage of medication in five patients or low doses of steroids in seven patients.

The condition of six patients remained improved, and no other drugs were prescribed, but these patients remained dependent on IVIG infusions.

Seven of the 25 patients who responded well to IVIG treatment relapsed at an average of 17.1 months (between four and 23 months) after the discontinuation of IVIG.