Prognosis in adult polymyositis.

The effects of long-term corticosteroid treatment have been assessed in 20 patients with polymyositis. Cases were only accepted if a muscle biopsy showed the characteristic features of inflammation and muscle fibre degeneration. If the muscle disorder was only a minor feature of generalised collagen disease or there was evidence of coexisting neuropathy, the patients were excluded. Over a mean follow-up period of 5 years, 8 patients died and only 4 improved. These results have been compared with those in other series. An attempt has been made to correlate muscle biopsy findings with prognosis, and the reasons for the poor outcome are discussed.