Circulating CHI3L1 autoantibodies serve as a diagnostic biomarker in patients with obstructive sleep apnea.

While polysomnography (PSG) is the gold standard for diagnosing obstructive sleep apnea (OSA), its limited availability means that many patients remain undiagnosed. This study seeks to evaluate whether CHI3L1-Ab could serve as a diagnostic biomarker for OSA. A total of 366 individuals, including 333 OSA patients and 33 healthy controls, were recruited for this study, all of whom underwent polysomnography. Enzyme-linked immunosorbent assay (ELISA) was used to measure CHI3L1-Ab levels, and clinical factors were analyzed to assess their relationship with CHI3L1-Ab expression. OSA patients exhibited significantly higher CHI3L1-Ab levels compared to healthy controls (P < 0.05), with an area under the curve (AUC) of 0.721. Subgroup analysis revealed the highest AUC of 0.735 (95% CI 0.637-0.832) in patients with severe OSA. Logistic regression analysis, which incorporated age, BMI and CHI3L1-Ab levels, demonstrated strong predictive performance with an AUC of 0.846 (95% CI 0.815-0.942). The corresponding nomogram allowed individualized risk estimation based on these predictors. The combination of CHI3L1-Ab levels, age and BMI demonstrated strong predictive accuracy in distinguishing OSA from healthy individuals. These findings also suggest that elevated CHI3L1-Ab levels could serve as an independent diagnostic biomarker for OSA.