Association between the Nutritional Risk Index and stroke: Evidence from NHANES 2011–2020

Using NHANES data (2011-2020), we assessed the association between the Nutritional Risk Index (NRI) and stroke risk among 22,839 adults (mean age, 49.61 ± 17.07 years), including 910 individuals (3.98%) with stroke. Weighted multivariable logistic regression and restricted cubic spline (RCS) analysis were used to characterize the association, with subgroup analyses to examine consistency across populations and mediation analyses to investigate the roles of lipid and inflammatory biomarkers. Higher continuous NRI was inversely associated with stroke, with each 1-unit increase associated with 4% lower odds (OR = 0.96, 95% CI: 0.95-0.97), and participants in the highest NRI quartile (Q4) had a significantly lower stroke risk than those in the lowest NRI quartile (Q1) (OR 0.60, 95% CI 0.42-0.85). RCS analysis indicated a linear relationship (P for nonlinearity >0.05), and the protective effect of higher NRI remained robust across nearly all subgroups examined. Mediation analyses revealed that total cholesterol, systemic immune-inflammation index, platelet-neutrophil product, neutrophil-to-lymphocyte ratio, and lymphocyte-to-monocyte ratio each partially mediated the NRI-stroke association, with mediation effects ranging from 1.71% to 13.65%. These findings suggest that favorable nutritional status, reflected by higher NRI, is linked to lower stroke risk, with lipid metabolism and inflammation playing mediating roles in this association. Further longitudinal and mechanistic studies are warranted.