IL18 and adult-onset Still disease: Using the cutoff value of <2006 U/mL of sIL-2R distinguished the AOSD group from the adult HLH group with 77.4% sensitivity and 69.6% specificity (ROC-AUC 0.81, 95%CI: 0.71–0.91, p<0.0001, Figure 2B), indicating that the differential diagnostic ability of IL-18 was superior to that of sIL-2R.