Association between the C-reactive protein-triglyceride-glucose index and obstructive sleep apnea risk: Mediating role of body mass index in U.S. adults.

Obstructive sleep apnea (OSA) is characterized by intermittent hypoxia, fragmented sleep, and heightened sympathetic activity, drivers of oxidative stress, systemic inflammation, and metabolic dysregulation. The C-reactive protein-triglyceride-glucose index (CTI) has recently emerged as a composite marker of inflammatory and metabolic states. This study aimed to investigate the association between the CTI index and OSA risk in a nationally representative United States adult population. We analyzed data from 4564 participants in the 2015 to 2018 National Health and Nutrition Examination Survey. Logistic regression, restricted cubic spline modeling, and subgroup analyses were performed to examine the association between CTI and OSA risk. Predictive performance of CTI was compared with triglyceride-glucose and C-reactive protein using receiver operating characteristic curves. Mediation analysis assessed the role of body mass index (BMI). Higher CTI was positively associated with increased OSA risk, and no significant evidence of nonlinearity was observed (P for nonlinear = .424). Each unit increase in CTI corresponded to a 43% higher odds of OSA, and those in the highest quartile had over twice the odds compared with the lowest. CTI showed slightly higher discriminatory ability than the TyG index and CRP, although its overall discriminative performance remained modest. BMI statistically mediated 56.3% of the observed association. Findings were consistent across subgroups. CTI was independently associated with OSA among United States adults, with BMI accounting for a substantial proportion of this association. As a readily available biomarker integrating inflammatory and metabolic information, CTI may provide additional value for OSA risk assessment.