Abstract: Objective To investigate the life threatening factors of dermatomyositis(DM).Methods 216 cases of DM were collected from the Peking Union Medical College Hospital in 1970 to 1997.The criteria for the diagnosis of DM were based on the report of Bohan and Peter in 1975.The mean follow up period of these patients was 5.8±4.7 years (ranged from 2 to 27 years).The clinical and laboratory data were retrospectively analysed with the SAS and Stata statistical software package,chisquare test was used for monofactorial study,and multiple factors were analysed using logistic regression.Results There were 43 out of 216 DM patients (19.9%) died;among them,18 out of 24 (11.1%) complicated with malignancy,13 out of 32(14 8%)complicated with pulmonary fibrosis During the first year after onset,the mortality rate was quite high (9.7%) The survival rates were 87.5% in the second year and 81 5% in the fifth year respectively Life threatening factors were malignancy,pulmonary fibrosis and acute onset of the disease.Aging and cardiac disorders were not identified as a fatal risk factor in this series of patients.Conclusion Poor prognostic factors in DM were malignancy,pulmonary fibrosis and acute onset of the disease.

Key words: Dermatomyositis, Prognosis