CHI3L1 and juvenile idiopathic arthritis: On the other hand, analysis of correlations between YKL-40 levels and ADAMTS5 levels in the blood of patients with JIA revealed significant correlations between the above-mentioned variables in patients in the 3rd (r = 0.506, p < 0.001), 12th (r = 0.574, p < 0.001), and 18th (r = 0.491, p = 0.002) month of biological therapy.