CHI3L1 and obstructive sleep apnea syndrome: serum CIV and CHI3L1 levels were higher in the OSA group (n = 74) than in the control group, with a significant difference between the severe OSA and control groups (41.78 ± 8.72 vs. 45.52 ± 2.45 ng/ml, 34.79 ± 12.08 ng/ml vs. 60.9 ± 7.2 ng/ml, p < 0.05).