Therefore, it was hypothesized that the combination of these three laboratory tests could be used to predict and diagnose the severity of patients with anti-MDA5 antibody-positive PM/DM.ILD was found to be one of the most common systemic complications of IIM, and ILD associated with DM, especially in patients with anti-MDA5 antibody-positive CADM, has a rapid progression and poor prognosis. Here, IFIH1 is linked to polymyositis.