HLA-DRB1 and juvenile idiopathic arthritis: RF-positive polyarticular JIA was significantly associated with HLA-DRB1*04:05 and HLA-SE (OR = 5.1, 95% CI = 2.5–11, pc < 0.001; OR = 5.3, 95% CI = 2.5–11, Pc < 0.001, respectively) (Table 2).