[Plasma exchange in dermatomyositis and polymyositis. Retrospective study of 38 cases of plasma exchange].

In order to evaluate the efficacity of plasma exchanges (PE) in dermatomyositis and polymyositis, the case histories of 38 patients, who had undergone plasma exchanges between 1980 and 1986 in 10 French plasmapheresis centers, were studied. Large volume PE were performed in 34 patients after failure of conventional therapy and were part of the initial regimen for the 4 others. The initial activity of the muscle disease was acute in 27 patients and subacute or chronic in 11 cases. Clinical results were evaluated on a functional scale based on changes in muscle force: 24 patients improved (10 appreciably and 14 moderately) and 14 remained unchanged. PE were well tolerated in 23 patients. But side effects occurred in 15 patients, necessitating treatment withdrawal in 4 cases. PE seem to be more effective when the dermatomyositis is acute and evolutive than when it is chronic and insidious. The encouraging results of this exhaustive retrospective study prompt us to set up a prospective randomized trial.