Idiopathic inflammatory myopathy (IIM) is an autoimmune disease characterized by chronic muscle weakness and myositis with unknown etiology. IIM may affect the function of multiple organs and has a poor prognosis. In the present study, the causes of mortality in patients with IIM admitted to the Xiangya Hospital during the last 14 years were investigated. The investigation included an analysis of frequent causes of IIM, and of infections and associated complications. A cohort study was conducted on 676 patients with IIM that were admitted to Xiangya Hospital from January, 2001 to January, 2015. There were 49 patient mortalities (7.2% of the total cases), of which 34 mortalities were infection-associated and 15 were not infection-associated. The proportion of infection-associated IIM mortalities had increased since 2001. Of the 34 infection-associated mortalities, 31 cases (63.3%) were of fungal and bacterial infections, most frequently infecting the lungs and the blood. Klebsiella pneumoniae and Acinetobacter baumannii were the most commonly isolated pathogens, and co-infection with the two pathogens was observed in the majority of cases. In the IIM mortalities not associated with infection, there were 2 acute myocardial infarction cases, 2 acute interstitial lung disease cases, 4 malignancies and 1 case of each of the following: Arrhythmia, pneumothorax, ventilator weakness, pulmonary artery hypertension, gastrointestinal bleeding, liver failure and renal failure. Three mortalities were secondary to viral hepatitis in the present study. Pathogenic infection was the most frequent cause of mortality in patients with IIM. The remaining causes of mortality included secondary to heart failure, lung dysfunction and malignancy. Following the ubiquitous application of glucocorticoids and immunosuppressants, the proportion of infection-associated mortalities increased in patients with IIM. Thus, in addition to focusing on the primary disease, infection should receive increased attention during clinical practice.
Keywords: dermatomyositis; idiopathic inflammatory myopathies; polymyositis.