Abstract
<title>Abstract</title> <p>Purpose The aim of this study is to investigate the effects of geriatric nutritional risk index (GNRI) and relative fat mass (RFM) on metabolic syndrome (MetS) and all-cause mortality in the elderly, and to evaluate their interaction. Methods Use data from the National Health and Nutrition Examination Survey (NHANES) from 1999 to 2018. Recruit 6896 participants aged 60 and above with complete data. Survey-weighted logistic regression was deployed to quantify the correlations of the two exposure markers with MetS. Weighted Cox regression was separately adopted to evaluate their associations with total mortality. Restricted cubic spline (RCS) models were fitted to visualize non-linear dose-response tendencies between exposures and outcomes. Compare survival differences using Kaplan Meier curves, and explore interaction effects using subgroup analysis and multiplicative with additive interaction analysis. Results After adjusting for confounders, GNRI was independently associated with all-cause mortality but showed no significant correlation with MetS. RFM was significantly associated with MetS but did not show an independent association with all-cause mortality. RCS analysis revealed nonlinear associations between GNRI and mortality risk as well as MetS, and between RFM and MetS. The Kaplan Meier curve further confirms that the survival rate in the low GNRI group significantly decreases. NO significant interaction between RFM and GNRI in two different outcomes. Conclusion GNRI acts as an independent prognostic marker for total mortality among older adults. RFM is significantly associated with the development of MetS. There is no significant interaction between the two indicators in two different outcomes.</p>