Are respiratory complications common causes of death in inflammatory myopathies? An autopsy study

Background and objective: Polymyositis (PM) and dermatomyositis (DM) are idiopathic inflammatory myopathies that are associated with a variety of clinical manifestations including pulmonary complications. The objective of the present study was to determine the causes of deaths in this complex patient population. Methods: A computer-assisted search of medical and autopsy records identified a total of 39 patients with either PM or DM who underwent an autopsy at the Mayo Clinic (Rochester, MN, USA) over a 29-year period from 1 January 1981 to 31 December 2009. The immediate causes of death along with contributing causes were determined by reviewing all available clinical data and autopsy findings. We also analysed the discordance between ante-mortem clinical diagnoses provided by clinicians and the final diagnosis by the post-mortem analysis. Results: Respiratory (33%), infectious (28%) and cardiovascular diseases (26%) accounted for the majority of immediate causes of death. Acute exacerbation of chronic interstitial lung disease (15%) and bronchopneumonia (15%) were the most common specific causes. Immediate cause of death was not suspected in nearly one third of cases and included bronchopneumonia, sepsis, acute myocardial infarction, aspiration pneumonia, pulmonary embolism, aortic stenosis, mycotic aneurysm rupture and acute haemoperitoneum. Conclusions: We conclude that pulmonary injury is the immediate cause of death in one third of patients with PM/DM; acute exacerbation of chronic interstitial lung disease and bronchopneumonia were the most common specific causes. Immediate cause of death was not established ante-mortem in nearly one third of cases, and some of these causes were treatable. The causes of death in patients with inflammatory myopathies have not been extensively evaluated. We reviewed autopsy data from patients with inflammatory myopathies seen at our institution and show that respiratory complications are common and often unsuspected causes of death.