Objective To analyze the correlation between body mass index(BMI) and stroke risk in people aged 40 years and above in Fuyang City, and explore the interaction between BMI and other risk factors such as lifestyle and clinical indicators in the stroke risk.

Methods A multi-stage stratified random sampling method was adopted to conduct a cross-sectional survey among 3 835 residents aged 40 years and above in Fuyang City.Non-parametric test and χ² test were used to analyze the univariate association between each index and stroke.Further, the multivariate logistic regression model was applied to evaluate the independent influence and interaction of BMI and other factors, and the optimal cut-off value of BMI for predicting stroke was determined through the receiver operating characteristic(ROC) curve.

Results The results of multivariate logistic regression showed that BMI, age, dyslipidemia, and hypertension, etc.were all independent risk factors of the occurrence of stroke(P < 0.05 to P < 0.01).Taking BMI < 24 kg/m² as the control group, the association between the BMI and stroke risk was further explored.The stratified analysis results of BMI showed that the stroke risk in the 24-28 kg/m² group was 2.129 times that of the control group(95%CI: 1.316-3.444, P < 0.01).The stroke risk in the >28 kg/m² group was 1.631 times that of the control group(95%CI: 1.030-2.582, P < 0.05).After adjusting the covariates such as gender, age and educational level, all three models showed that BMI was an independent risk factor of stroke.The results of ROC curve analysis showed that the optimal cut-off point of BMI for predicting stroke was 24.5 kg/m², with an area under the curve of 0.727(95%CI: 0.473-0.955), a sensitivity of 72.3% and a specificity of 70.0%.

Conclusions BMI is an independent risk factor of stroke among people aged 40 years and above in Fuyang City.When BMI is ≥24 kg/m², it may have a synergistic effect with other risk factors(such as age, hypertension and dyslipidemia), jointly increasing the risk of stroke.