CHI3L1 and asthma: Serum YKL-40 levels in patients with severe asthma were higher than the levels in the moderate asthma group (85.60 [56.2-94.3] ng/ml vs. 76.00 [52.9-86.0] ng/ml; p = 0.024) and the mild asthma group (85.60 [56.2-94.3] ng/ml vs. 63.05 [53.6-75.3] ng/ml; p < 0.001).