MUC1 and dermatomyositis: Previous reports revealed that several prognostic factors, including positive anti-MDA5 antibody, high serum ferritin level before treatment, high alveolar-arterial oxygen difference (AaDO2), low % forced vital capacity, and high total ground-glass opacity (GGO) score before treatment, and elevation of Krebs von den Lungen-6 (KL-6) at 2–4 weeks after the beginning of treatment, were poor prognostic factors of DM-IP16–25.