The association between red blood cell distribution width-to-albumin ratio and risk of stroke: A cross-sectional analysis of NHANES

Objectives The red blood cell distribution width-to-albumin ratio (RAR) is a novel biomarker that integrates inflammatory, oxidative, and nutritional status and has shown potential for predicting cardiovascular risk. However, its association with stroke risk in the general population has not been adequately explored. This study aimed to assess the relationship between RAR and the prevalence of stroke using nationally representative data from the NHANES. Methods Data from 35,618 U.S. adults who participated in NHANES cycles from 2005 to 2018 were analyzed. RAR was calculated as the ratio of red blood cell distribution width (RDW) to serum albumin and categorized into quartiles: Q1 (2.15–2.86), Q2 (2.86–3.09), Q3 (3.09–3.40), and Q4 (> 3.40). Stroke status was self-reported based on physician diagnosis. Weighted multivariable logistic regression, restricted cubic spline modeling, and subgroup analyses were conducted to examine the association, adjusting for demographic, socioeconomic, behavioral, and clinical variables. Results A significant nonlinear association between RAR and stroke prevalence was observed, with an inflection point at RAR = 3.49. Below this threshold, each unit increase in RAR was associated with a 95% higher likelihood of stroke (OR = 1.95, 95% CI: 1.52–2.50, p < 0.0001). Participants in the highest quartile (Q4) of RAR had an 82% increased risk of stroke compared to those in the lowest quartile (Q1) (OR = 1.82, 95% CI: 1.48–2.24, p < 0.0001). Subgroup analyses revealed stronger associations in individuals without hypertension (OR = 1.74 vs. 1.27 with hypertension, p-interaction = 0.0024), diabetes (OR = 1.48 vs. 1.21 with diabetes, p-interaction = 0.0330), or coronary heart disease (OR = 1.47 vs. 1.07 with disease, p-interaction = 0.0095). Conclusions This study demonstrates a nonlinear positive association between RAR and stroke prevalence, with a particularly strong effect below RAR = 3.49 and in individuals without established cardiovascular comorbidities. RAR may serve as a valuable, easily accessible biomarker for stroke risk stratification.