The IL-18 levels of AOSD patients (3016.2 ± 2389.4 pg/mL) were higher than those of RA patients (121.5 ± 234 pg/mL, p < 0.001) and HC (30 ± 31.8 pg/mL, p < 0.001). This evidence concerns the gene IL18 and adult-onset Still disease.