Treatment of inflammatory myopathies

Abstract

Idiopathic inflammatory myopathies, notably polymyositis and dermatomyositis are comparatively uncommon diseases and few randomised, double blind placebo controlled trials have been done. Final validation of measures to assess outcome and response to treatment is awaited. Corticosteroids are an effective initial treatment, although rarely tested in randomised controlled trials. Unfortunately, not all patients respond to them and many develop undesirable side effects. There is thus a need for second line agents notably immunosuppressives or intravenous immunoglobulin. There are no defined guidelines or best treatment protocols agreed internationally and so the medical approach must be individualised, based on the severity of clinical presentation, disease duration, presence of extramuscular features, and prior therapy and contraindications to particular agents. There is still a significant percentage of non-responders (around 25%) and clinical relapses. Novel therapeutic approaches are now directed towards cytokine modulation and the use of monoclonal antibodies targeting B and T cells.