Infections as a predominant cause of death in adult patients with idiopathic inflammatory myopathies.

Objectives: To evaluate causes of death in the single-centre Polish cohort of patients with idiopathic inflammatory myopathies (IIM) and to identify risk factors associated with fatal outcomes.

Methods: Electronic medical database was retrospectively analysed, data on the clinical symptoms, serological profiles, administered treatment and outcomes in IIM patients were collected. Two subgroups were distinguished - the deceased and the survived group. Statistical analysis was performed to identify differences between the subgroups and risk factors contributing to fatal outcomes.

Results: 79 patients with IIM were identified, most frequently with antisynthetase syndrome, dermatomyositis and polymyositis. Among them 9 patients (11.39%) deceased. The mean age at the time of diagnosis was 57.10 ± 14,59years old. Median diagnostic delay reached 5 months. The majority of the deaths (77.78%) occurred within the first 18 months after IIM diagnosis. As compared to the survivors, patients with fatal outcomes were more frequently affected by cardiac involvement (p=0.026), suffered from concomitant autoimmune disorders (p=0.028) were treated with mycophenolate mofetil (p=0.005) and cyclophosphamide (p=0.006). 89.89% of all deaths in our cohort were caused by various infections, predominantly of the respiratory tract. Although 10.13% of the patients had a history of malignancy, none of the deaths was caused by malignancy.

Conclusions: Patients with IIM associated with cardiac involvement and concomitant autoimmune diseases may be at higher risk of fatal outcomes. Infections were the predominant cause of death in our cohort of patients. The majority of fatal outcomes occurred at the relatively early stage of the disease.