Multivariate Cox hazard analysis also confirms that serum HMGB1 higher levels in PM/DM patients (≥ 14.5 ng/ml, ROC cutoff value) (HR = 2.10; 95% CI 1.13–5.52; p = 0.023) are an adverse prognostic factor. The gene discussed is HMGB1; the disease is dermatomyositis.