C-reactive protein-triglyceride glucose index is a reliable biomarker for osteoarthritis: A cross-sectional study based on NHANES 1999-2018.

Osteoarthritis (OA) is a prevalent degenerative joint disease with strong links to chronic inflammation and metabolic risk factors, yet comprehensive biomarkers for early risk stratification and prognosis are still lacking. The C-reactive protein-triglyceride-glucose index (CTI), as a novel composite marker reflecting both insulin resistance and systemic inflammation, may serve as a useful tool for OA risk assessment and management. We analyzed data from 10,372 participants of the National Health and Nutrition Examination Survey (NHANES) conducted between 1999 and 2018. The association between CTI and the prevalence of OA as well as all-cause mortality was assessed using multivariate logistic regression models, Cox regression models, restricted cubic spline functions, and receiver operating characteristic curves. CTI was significantly associated with OA prevalence (fully adjusted OR = 1.35, 95% CI: 1.21-1.50, P < .001) and showed better predictive performance than either C-reactive protein or triglyceride-glucose index alone. Among the 1064 OA patients, elevated CTI values were independently associated with increased all-cause mortality (HR = 1.24, 95% CI: 1.03-1.50, P = .02), demonstrating a clear dose-response relationship. In this cross-sectional study, CTI was strongly associated with the prevalence of OA and all-cause mortality in patients with OA. However, causality could not be inferred from these observational data.