Survival, mortality and causes of death in inflammatory myopathies

To investigate the causes of death, survival and clinical factors associated with mortality, in a group of Spanish patients with inflammatory myopathies (IM) followed in the same University Hospital during a 25 year period.

A cross sectional study was performed, including 107 patients diagnosed with IM according to the Bohan and Peter criteria. Demographical and clinical information were extracted from the charts. Bivariate odds ratio with 95% confidence interval (CI) was used to measure the strength of association between variables. Kaplan-Meyer analysis was used to estimate survival. Univariate and multivariate Cox regression analysis were used to study clinical associations with mortality.

Twenty-eight patients (26%) died. Deaths were considered to be disease related in 21 cases. Main causes of death were cancer extension, cardiac involvement and lung involvement. Survival for the whole group was 92, 80 and 71% after 1, 5 and 10 years, respectively. By the log rank test, survival was lower for patients with cancer (p = 0.0001) as well as in those with cardiac involvement (p < 0.00001), compared to patients without these conditions. Cox univariate analysis showed that mortality was associated with higher age at IM onset, left ventricular dysfunction, the presence of cancer and the smoking habit. In Cox multivariate analysis, only left ventricular dysfunction (HR = 4.6; 95%CI 2.0-10.3; p > 0.0001) and the presence of cancer (HR = 3.3; 95%CI 1.4-7.4; p = 0.005) remained associated with mortality.

Although a great improvement has been achieved in the last decades in controlling IM, our study indicates that the mortality rate in this group of patients remains high. Cancer and cardiac involvement are important causes of death, and also prognostic factors for mortality in our group of patients. A careful search for cardiac involvement should be done in every patient with IM.