Influence of age at onset on the duration of treatment in idiopathic adult polymyositis and dermatomyositis.

Twenty-five patients with adult idiopathic dermatomyositis/polymyositis were followed for 59 +/- 39.3 months from initiation of therapy. Forty-two percent of the patients were able to discontinue prednisone therapy after 56 +/- 33 months of therapy and remained disease free for 34 +/- 35.2 months after discontinuing therapy. The mean dose of prednisone in 14 patients being treated at the end of the follow-up period was 16.0 mg. A positive correlation between age at diagnosis and duration of therapy was noted, but not with the creatine kinase value at diagnosis. Sex and dermal involvement were also not associated with treatment duration. All seven patients who received immunosuppressants continued to receive treatment during the follow-up period.