IFIH1 and dermatomyositis: Risk factors predicting poor prognosis have been established in polymyositis (PM)/DM patients including age, serum ferritin level, skin ulcers, partial arterial pressure of oxygen (PaO2) and anti-MDA5 antibody [2, 9–11], among which anti-MDA5 antibody was consistently reported as poor prognostic risk factor in most studies [12].