Association of the combined triglyceride-glucose and frailty index with chronic kidney disease: evidence from two national cohort studies.

OBJECTIVE

This study aimed to explore the relationships between TyG-Frailty Index (TyGFI), a comprehensive indicator of the triglyceride-glucose (TyG) index and frailty index (FI), and the risk of chronic kidney disease (CKD).

METHODS

A total of 8721 participants from the China Health and Retirement Longitudinal Study (CHARLS) and 9670 participants from the U.S. National Health and Nutrition Examination Survey (NHANES) were included for cross-sectional study; while 4102participants from CHARLS were included for longitudinal study. For longitudinal study, cumulative TyGFI (CumTyGFI) is calculated, and the participants were categorized into four clusters on the basis of the dynamic changes in the TyGFI through K-means clustering. Multivariable logistic regression models and cox proportional hazards models were applied to estimate associations with CKD, with adjustment for demographic, clinical, and lifestyle covariates. Restricted cubic spline (RCS) and subgroup analyses were used to explore dose-response relationships and interaction effects, respectively.

RESULT: Higher TyGFI, older age, hypertension, diabetes, and dyslipidemia were associated with CKD. In fully adjusted models, the highest TyGFI quartile (CHARLS: OR 3.98, 95% CI 3.03-5.22; NHANES: OR 4.49, 95% CI 3.55-5.69), highest CumTyGFI quartile (HR 4.18, 95% CI 3.09-5.65), and "increasing TyGFI alteration" cluster (HR 3.56, 95% CI 2.69-4.71) all showed significant associations, with dose‑response trends confirmed by RCS.

CONCLUSION

In two national datasets, higher TyGFI was associated with prevalent CKD in the cross-sectional analyses and with incident CKD in the longitudinal CHARLS analysis. TyGFI may serve as a compact epidemiological marker combining metabolic and frailty-related burden, although its predictive and clinical utility requires further validation.