The following multivariate logistic regression analysis identified IFN-γ (p = 0.017), spleen SUVmean (p = 0.035), and anti-MDA5 antibody (p = 0.049) as clinical factors that were significantly correlated with development of sHLH in IIM patients (Supplementary Table 7). Here, IFNG is linked to acquired idiopathic inflammatory myopathy.