A CONTROLLED TRIAL OF HIGH-DOSE INTRAVENOUS IMMUNE GLOBULIN INFUSIONSAS TREATMENT FOR DERMATOMYOSITIS

Background. Dermatomyositis is a clinically distinct myopathy characte rized by rash and a complement-mediated microangiopathy that results i n the destruction of muscle fibers. In some patients the condition bec omes resistant to therapy and causes severe physical disabilities. Met hods. We conducted a double-blind, placebo-controlled study of 15 pati ents (age, 18 to 55 years) with biopsy-proved, treatment-resistant der matomyositis. The patients continued to receive prednisone (mean daily dose, 25 mg) and were randomly assigned to receive one infusion of im mune globulin (2 g per kilogram of body weight) or placebo per month f or three months, with the option of crossing over to the alternative t herapy for three more months. Clinical response was gauged by assessin g muscle strength, neuromuscular symptoms, and changes in the rash. Ch anges in immune-mediated muscle abnormalities were determined by repea ted muscle biopsies. Results. The eight patients assigned to immune gl obulin had a significant improvement in scores of muscle strength (P<0 .018) and neuromuscular symptoms (P<0.035), whereas the seven patients assigned to placebo did not With crossovers, a total of 12 patients r eceived immune globulin. Of these, nine with severe disabilities had a major improvement to nearly normal function. Their mean muscle-streng th scores increased from 74.5 to 84.7, and their neuromuscular symptom s improved. Two of the other three patients had mild improvement, and one had no change in his condition. Of 11 placebo-treated patients, no ne had major improvement, 3 had mild improvement, 3 had no change in t heir condition, and 5 had worsening of their condition. Repeated biops ies in five patients of muscles whose strength improved to almost norm al showed an increase in muscle-fiber diameter (P<0.04), an increase i n the number and a decrease in the diameter of capillaries (P<0.01), r esolution of complement deposits on capillaries, and a reduction in th e expression of intercellular adhesion molecule 1 and major-histocompa tibility-complex class I antigens. Conclusions. High-dose intravenous immune globulin is a safe and effective treatment for refractory derma tomyositis.