Survival Analysis and Risk Factors for Survival in Idiopathic Inflammatory Myopathies: a Retrospective Cohort Study

Objective To study predominant risk factors for survival in idiopathic inflammatory myopathies(ⅡM). Methods The clinical data of 163 cases of ⅡM were reviewed, who received the diagnosis and treatments in West China Hospital from January 1997 to December 2010. Kaplan-Meier survival curve was used for the survival analysis of these patients with ⅡM. Univariate and multivariate analysis of risk factors for survival in the patients with ⅡM were carried out by Log-rank test, univariate Cox regression analysis and Cox regression model respectively. Results There were 21 death occured among 163 patients with ⅡM, and the estimated 3, 5, 10-year survival rate was 93%, 89%, 80% respectively. The mortality of the patients with dermatomyositis(DM) or amyophathic dermatomyositis(ADM) increased significantly when compared with polymyositis(PM,P=0.033,P=0.06). The mortality of ⅡM patients complicated with tumor or cadiovascular involvement was much higher than that of those patients without any complications (P<0.001,P=0.015). Tumor and cadiovascular involvement were two independent risk factors for the survival of ⅡM individuals. Conclusion DM and ADM have much unfavorable prognosis than PM. Tumor and cadiovascular involvement are two major risk factors for the survival of ⅡM patients.