Mortality of Chinese patients with polymyositis and dermatomyositis

Objective To investigate the mortality and the causes of death in Chinese patients with polymyositis (PM) and dermatomyositis (DM). Methods The clinical data of all consecutive adult PM/DM patients in Rheumatology and clinical immunology department of Peking University First Hospital from January 2007 to Apr2016 were collected. The primary causes of death were identified, the standardized mortality ratio (SMR) and years of life lost (YLL) were calculated based on the National Bureau of Statistics of China for the general population, the survival in the first decade was performed using Kaplan-Meier analysis, and the predictors of mortality were evaluated by multivariable cox regression. Results A total of 85 PM and226 DM cases were included and 68 patients died. Infection (52.3%) was the leading cause of death. The overall age and sex adjusted SMR was 6.0(95%CI 3.5–8.5) for PM, and 9.0(95%CI 6.8–11.2) for DM. The YLL of women and men were 12.2 and 18.3 years respectively for PM, and 37.5 and 28.4 years respectively for DM. The 10-year survival of patients with ILD, malignancy or infection was significantly worse than those without, respectively. The independent predictors of mortality for PM/DM patients were age at disease onset, malignancy and infection. Conclusions Mortality of PM/DM patients in China is substantial, especially in females, and those with ILD, malignancy or infection. Infection was the leading cause of death. Patients with older age at onset, infection, ILD, and malignancy need to be paid more attention. Key Points • This is the first comprehensive report about the mortality situation with a large population in PM/DM patients in China including SMR, YLL, and cause of death, Kaplan-Meier survival analysis and Cox regression analysis for mortality risk factors. • The specific SMRs for PM/DM patients with malignancy and interstitial lung disease were also reported in this study. To our knowledge, only two studies worldwide reported SMRs in PM/DM patients and no figure about YLL was reported so far. • Overall, the mortality figures in this study were higher than those from the western countries, and the leading cause of death was different from the western countries.