Association between C-reactive protein-triglyceride glucose index and risk of sarcopenia in older adults: findings from CHARLS and NHANES

BACKGROUND: Insulin resistance (IR) and inflammation are two crucial risk factors of sarcopenia. C-reactive protein-triglyceride glucose index (CTI) has been proposed to be a novel biomarker reflecting IR and inflammation. However, association between CTI and sarcopenia risk remains unclear. AIM: To explore the association between CTI and sarcopenia risk. METHODS: Data were obtained from Nutrition Examination Survey (NHANES) 2001-2010 and China Health and Retirement Longitudinal Study (CHARLS) 2011-2015. NHANES was used for cross-sectional analysis, and weighted logistic regression analysis was conducted to explore association between CTI and sarcopenia. CHARLS was used for longitudinal analysis, and the primary endpoint was the first occurrence of sarcopenia over follow-up. Logistic regression analysis and Cox proportional hazard analysis were conducted to explore the relationship between CTI and the risk of sarcopenia. Restricted cubic spline (RCS) analysis was performed to investigate the non-linear association between CTI and sarcopenia risk, and receiver operating characteristics (ROC) curves and the area under the ROC curve (AUC) were utilized to assess the predictive capability of CTI on the risk of sarcopenia. RESULTS: A total of 11,286 Americans and 1478 Chinese aged ≥60 years were included in this study. Logistic and Cox regression analysis revealed the cross-sectional (OR: 1.52, 95 %CI: 1.15-1.99, P = 0.004) and longitudinal (HR: 1.35, 95 %CI: 1.10-1.65, P = 0.004) correlation between CTI and sarcopenia risk after adjusting the covariates. For the two databases, non-linear association between CTI and sarcopenia risk was observed (P for non-linear <0.001). Additionally, compared to CRP and the TyG index, CTI exhibited the best predictive capability for sarcopenia risk, with the highest AUC (CHARLS: 0.730, NHANES: 0.722). CONCLUSION: There exist both the cross-sectional and longitudinal association between CTI level and sarcopenia risk in older adults, and it is crucial to monitor CTI in the prevention and treatment of sarcopenia.