Association between the Geriatric Nutritional Risk Index and sarcopenia in American adults aged 45 and older

Objectives: Nutrition is closely related to the occurrence of sarcopenia. Evidence shows that sarcopenia has a serious impact on population health and the social economy. Geriatric Nutritional Risk Index (GNRI) is a useful prognostic predictor for several chronic diseases. Our original intention was to investigate whether GNRI correlates with sarcopenia.

Methods: We included 4,709 adults aged 45 years and older from the National Health and Nutrition Examination Survey from 2009 to 2018 in this cross-sectional study. According to the level of GNRI, they were categorized into High-GNRI and Low-GNRI groups, while sarcopenia was assessed using skeletal muscle index. Multivariate logistic regression was employed to investigate the independent relevance between the GNRI and the prevalence of sarcopenia. We examined the linear or nonlinear relevance between GNRI and sarcopenia using the Restricted Cubic Spline (RCS) curve, and the threshold effect was analyzed. We explored whether some specific populations are more susceptible to GNRI affecting the occurrence of sarcopenia through subgroup analysis.

Results: The incidence of sarcopenia was substantially reduced in the High-GNRI group (17.7% vs. 13.2%; p = 0.013). We found that GNRI is an essential predictor of sarcopenia (OR: 0.57; 95%CI: 0.41-0.79; p = 0.001). The occurrence of sarcopenia was reduced by increasing GNRI. Subgroup analysis showed that some specific populations were more susceptible to GNRI, which reduced the incidence of sarcopenia in individuals. These populations included high school graduates and above (p = 0.006), non-Hispanic white (p = 0.045), married or living with a partner (p = 0.03), and non-diabetic (p = 0.021). The RCS curve showed a non-linear inverse relevance between GNRI and sarcopenia (non-linear p = 0.033), with a threshold identified at GNRI = 91.935.

Conclusions: GNRI is a reliable predictor of sarcopenia in Americans aged 45 and older, with a nonlinear inverse relationship identified at a threshold GNRI of 91.935.