Polymyositis and dermatomyositis: short term and longterm outcome, and predictive factors of prognosis.

OBJECTIVE: To assess short term and longterm outcome of polymyositis (PM) and dermatomyositis (DM), and predictive variables of PM/DM course.

METHODS: The medical records of 77 consecutive patients with PM/DM were reviewed. The criteria for PM/DM diagnosis were based upon Bohan and Peter criteria.

RESULTS: Thirty-one patients (40%) achieved remission of PM/DM, whereas 33 (43%) improved and 13 (17%) worsened their clinical status. Short term recurrences of PM/DM (during tapering of therapy) occurred in 36 patients and longterm recurrences (after discontinuation of therapy) in 9 patients. PM/DM were associated with both decreased functional status and quality of life at longterm followup: (1) only 52% of patients considered to be in remission experienced a return to previous normal activities; and (2) 45% of the other patients with nonremitting PM/DM still had a marked reduction of activities (as shown by the disability scale of the Health Assessment Questionnaire). Overall mortality was as high as 22%, and the main causes of death were cancer and lung complications. Factors associated with PM/DM remission were younger age and shorter duration of clinical manifestations prior to therapy initiation. Variables associated with poor outcome of PM/DM were older age, pulmonary and esophageal involvement, and cancer.

CONCLUSION: Our series shows both high morbidity and mortality related to PM/DM, emphasizing that management of PM/DM patients at an early stage is required. Lung complications (i.e., aspiration pneumonia due to PM/DM related esophageal dysfunction and ventilatory insufficiency) were one of the main causes of death in our series, indicating that investigating for subclinical esophageal and lung impairment should become an integral part of initial PM/DM evaluation. The presence of poor prognostic factors should prompt both close followup and aggressive therapy in patients with PM/DM.