Current treatment of the inflammatory myopathies

Among the main concerns regarding the current therapy for the inflammatory myopathies are a lack of adequate controlled trials, a lack of objective means to reliably measure muscle strength, lack of natural history data, consideration of polymyositis, dermatomyositis, and inclusion-body myositis as a homogeneous group of inflammatory myopathies, and reliance on nonspecific markers for determining prognosis and assessing response to therapies. Prednisone remains the drug of choice in treating these disorders, although a controlled trial has never been undertaken to study its efficacy. Among the steroid-sparing agents, azathioprine, methotrexate, cyclosporine, and chlorambucil are used with invariably low to moderate success. There are no results of controlled trials to indicate whether one of these drugs is superior to another. Intravenous immunoglobulin, which is very expensive, was shown in a controlled trial to be effective in steroid-resistant dermatomyositis not only in dramatically improving muscle strength and skin rash but also in resolving the underlying immunopathology. Controlled trials of intravenous immunoglobulin in patients with polymyositis and inclusion-body myositis are under way. Inclusion-body myositis has emerged as a common inflammatory myopathy that is predictably disabling and resistant to most therapies.