Body mass index and all-cause mortality in US stroke population: a cohort study

BACKGROUND: Obesity and overweight are major global health concerns, associated with increased rates of stroke and mortality. This study sought to investigate the relationship between BMI and all-cause mortality among stroke patients in the United States. METHODS: This study utilized data from 1,603 stroke survivors from the National Health and Nutrition Examination Survey (NHANES) cycles (1999-2018) linked to the National Death Index. BMI was calculated and grouped into normal weight (BMI < 25 kg/m²), overweight (25 ≤ BMI < 30 kg/m²), or obese (BMI ≥ 30 kg/m²). RESULTS: : 0.75 [95% CI: 0.61-0.91], p = 0.004). Subgroup analysis found stronger negative correlations between participants aged 60 years, women, non-Hispanic whites, and non-Hispanic blacks. A gender interaction was observed, suggesting varying effects of BMI on survival between males and females. The restricted cubic spline model indicated a non-linear relationship, with an inflection point at a BMI of 30.26 kg/m². Below this threshold, BMI was inversely linked to mortality, while above it, the association leveled off. CONCLUSIONS: Stroke survivors with elevated BMI, particularly those categorized as overweight or obese, exhibit reduced all-cause mortality in comparison to individuals with normal or low BMI. Further investigation is necessary to clarify this paradox's mechanisms and improve clinical recommendations.