In particular, IL-18 and sIL-2R were more useful biomarkers to differentiate AOSD and adult HLH compared to ferritin (IL-18: OR 1.23, 95%CI 1.09–1.39, p=0.0010; sIL-2R: OR 0.80, 95%CI 0.70–0.92, p=0.0020). The gene discussed is IL18; the disease is adult-onset Still disease.