Evaluating cystatin-C and monocyte-to-high-density lipoprotein cholesterol ratio as indicators of obstructive sleep apnea severity in male patients

Runtian Meng Qiaowen Chen Chih-Yuan Ko ^*

• The Second Affiliated Hospital of Fujian Medical University, Quanzhou, China

Objectives: This study investigates the association between blood cystatin-C (Cys-C) and monocyteto-high-density lipoprotein cholesterol ratio (MHR), both established inflammatory markers, with the severity of obstructive sleep apnea (OSA) in male patients. Methods: A total of 117 male participants who underwent overnight polysomnography (PSG) between February 2019 and December 2022 were included. Based on the apnea-hypopnea index (AHI), participants were categorized into three groups: G1 (AHI < 5 events/hour, n = 9; control group), G2 (5 ≤ AHI < 30 events/hour, n = 32), and G3 (AHI ≥ 30 events/hour, n = 76). Serum Cys-C and MHR levels were measured and analyzed for their correlation with OSA severity. Multivariate logistic regression and receiver operating characteristic (ROC) analyses assessed their diagnostic value, while restricted cubic spline (RCS) analysis examined potential nonlinear relationships. Results: Cys-C and MHR levels increased with OSA severity and showed significant positive correlations with AHI (Cys-C: r = 0.084, P < 0.05; MHR: r = 0.1286, P < 0.05). In multivariate regression, MHR remained an independent correlate of OSA severity (adjusted OR = 47.130, 95% CI: 1.014-6.692, P = 0.008), whereas Cys-C lost statistical significance after adjusting for confounders. RCS analysis found no significant nonlinear relationship (P > 0.05). ROC analysis showed that combining Cys-C and MHR modestly improved diagnostic accuracy (AUC = 0.6622, 95% CI: 0.554-0.77). Subgroup analysis indicated that severe OSA patients with hypertension had higher Cys-C and MHR levels compared to those without hypertension, though the differences were not statistically significant (P > 0.05). Conclusions: Cys-C and MHR are positively associated with OSA severity, with MHR emerging as a stronger independent biomarker. Incorporating these markers into OSA risk stratification may enhance clinical assessment and targeted interventions. Future large-scale prospective studies are needed to validate their prognostic value and clinical utility.