Lower baseline S100A12 levels increased the likelihood of achieving a JIA-ACR100 response at month 3 by 2.7-fold (95% CI: 0.97–7.28), whereas lower baseline S100A12 plus lower CRP increased the likelihood by 3.9-fold (95% CI: 1.40–10.67). Here, S100A12 is linked to juvenile idiopathic arthritis.