Background: Sarcopenia poses a major global health issue, with intrinsic capacity (IC) linked to its risk. This study examined the link between IC and sarcopenia in middle-aged and older Chinese individuals, focusing on the mediating role of triglycerides-total cholesterol-body weight index (TCBI), a new easy-to-calculate nutritional indicator.

Methods: The investigation utilized 2015 data from the China Health and Retirement Longitudinal Study (CHARLS), focusing on individuals aged 45 years or older. Sarcopenia was evaluated using the 2019 guidelines from the Asian Sarcopenia Working Group. After adjusting for various confounders, we employed multiple logistic regression to explore the link between IC, TCBI, and sarcopenia, and used a mediation model to evaluate TCBI's role in the IC-sarcopenia. Subgroup analysis examined the heterogeneity among various groups.

Results: This research encompassed a cohort of 6,554 individuals, displaying an average age of 59.4 ± 9.1 years, comprising 5,758 non-sarcopenia and 796 sarcopenia individuals. Mean IC was 5.1 ± 1.0 for non-sarcopenia group and 4.4 ± 1.2 for sarcopenia group. In the non-sarcopenia group, the median TCBI was 1446.4, and the interquartile range (IQR) was 922.3-2283.4. In the sarcopenia group, the median TCBI was 841.6, and the IQR was 584.9-1304.1. Significant differences in IC and TCBI were observed between the non-sarcopenia and sarcopenia groups (p < 0.001). Following rigorous adjustment for all covariates, IC was inversely associated with sarcopenia, and the risk of sarcopenia decreased by 15% for each unit increase in IC (OR = 0.85, 95%CI: 0.76-0.95, p = 0.004). Higher TCBI was associated with a 28% decrease in sarcopenia risk per unit increase (OR = 0.72, 95% CI: 0.58-0.90, p = 0.004). TCBI's indirect effect on the IC-sarcopenia link was -4.91 × 10^-3 (p < 0.001), explaining 12.29% of the total effect variation.

Conclusion: The study found that IC is negatively correlated with sarcopenia, while TCBI is negatively correlated with sarcopenia, and TCBI mediates the relationship between IC and sarcopenia.

Keywords: CHARLS; cross-sectional study; intrinsic capacity; nutritional index; sarcopenia.

Copyright © 2025 Ding, Li and Zhao.

背景： 肌少症是一个重大的全球健康问题，其风险与内在能力（IC）有关。本研究考察了中老年人群中IC和肌少症之间的联系，并重点关注甘油三酯-总胆固醇-体重指数（TCBI），这是一种新的易于计算的营养指标，在其中间的作用。

方法： 该研究使用了2015年中国健康与退休纵向调查（CHARLS）的数据，关注45岁及以上的人群。肌少症根据亚洲肌少症工作组2019年的指南进行评估。在调整各种混杂因素后，我们采用多变量逻辑回归来探索IC、TCBI和肌少症之间的联系，并使用中介模型来评估TCBI在IC-肌少症关系中的作用。亚组分析考察了不同群体间的异质性。

结果： 本研究涵盖了一个由6554名个体组成的队列，平均年龄为59.4 ± 9.1岁，其中包括5758名非肌少症和796名肌少症个体。非肌少症组的平均IC为5.1 ± 1.0，而肌少症组则为4.4 ± 1.2。在非肌少症组中，TCBI的中位数是1446.4，四分位距（IQR）范围为922.3-2283.4。而在肌少症组中，TCBI的中位数是841.6，四分位距（IQR）范围则是584.9-1304.1。非肌少症和肌少症两组在IC和TCBI方面存在显著差异（p -3 （p

结论： 研究表明，IC与肌少症呈负相关，而TCBI也与肌少症呈负相关，并且TCBI在IC和肌少症之间起到了中介作用。

关键词： CHARLS；横断面研究；内在能力；营养指数；肌少症。