Background Idiopathic inflammatory myopathy is a group of systemic connective tissue diseases, including dermatomyositis (DM), polymyositis (PM) and inclusion body myositis (IBM). PM/DM are characterized by chronic muscle inflammation and can affect other internal organs. Survival rate and prognostic factors of PM/DM vary widely. The 5-year survival rates for PM/DM range from 60% to 95%. Additionally, the long-term outcome of a large group of Chinese patients with PM/DM is absent. Although Interstitial lung disease (ILD) and coexistent cancer were indicated to be predictors of mortality, few studies conducted multivariate regression analysis to provide independent prognostic factors, as well as the calculation of Standardized Mortality Ratio for PM/DM patients.
Objectives To analyze the survival rate, cause of death and the prognostic outcome factors in idiopathic inflammatory myopathy (IIM).
Methods A total of 201 IIM patients treated in Peking University People's Hospital from January 1996 to September 2013 were included. Medical records were abstracted for clinical, laboratory and therapeutic data.
Results The follow-up time of 201 IIM patients, including 121 with DM, 33 with PM and 47 with CADM, ranged from one to 492 months, and 56 cases were lost to follow up. Overall cumulative survival rate was 93.0%, 87.0%, 86.0% and 84.0% at 1, 3, 5 and 10 years respectively from the disease onset. The rates were similar in DM, PM and CADM. During the follow-up period, 26 (19.3%) patients died, among which 21 cases died within 3 years from the onset. Respiratory failure associated with ILD was the main cause of death, followed by cardiac involvement and coexistent malignancy. Rapidly progressive ILD, myalgia, fever, abnormal ECG, normal CKMB, lymphopenia and hypoalbuminemia, elevated LDH and CEA were associated with mortality (P<0.05). In multivariate Cox regression analysis, elevated CEA was the significant predictor of poor outcome. Therapy with glucocorticoids combined with immunosuppressants for more than one year was negatively correlated with mortality, as well as methylprednisolone pulse therapy for patients with rapidly progressive ILD. Intravenous cyclophosphamide therapy was associated with a better survival than MTX.
Conclusions The ten-year survival rate shows no statistically significant difference among DM, PM and CADM. The survival rate of patients with rapidly progressive ILD is significantly lower than patients with chronic or without ILD. Elevated CEA acts as the independent risk factor for poor prognosis. Glucocorticoids combined with immunosuppressants for more than one year is associated with high survival rate. Intravenous cyclophosphamide therapy is associated with a better survival than MTX.
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Disclosure of Interest None declared