Relationship between body mass index and the risk of hypertension in elderly patients with dyslipidemia

Objective To investigate the relationship between body mass index (BMI) and the risk of hypertension in elderly patients with dyslipidemia. Methods Dyslipidemia patients aged 60 years and above were selected from Tianjin surveillance points of China Chronic Disease Surveillance (2019-2023). The data of gender, age, height, blood pressure, BMI, disease history and other indicators were collected through cross-sectional survey. Chi-square test and multivariate logistic regression were used to analyze the influencing factors of hypertension. Restricted cubic spline curves were drawn to quantify the association between BMI and hypertension and identify the key nodes. Results A total of 25 229 patients with dyslipidemia were included in this study. The average age was (66.88±3.62) years old, and the prevalence of hypertension was 55.9% (14 109/25 229). Multivariate logistic regression analysis showed that after adjusting for confounding factors, for every 1 kg/m² increase in BMI, the risk of hypertension in elderly patients with dyslipidemia increased by 12% (OR=1.12, 95% CI 1.11-1.13, P<0.001). The risk of hypertension was 1.54 times higher in overweight group (OR=1.54, 95% CI 1.46-1.63, P<0.001), and 2.56 times higher in obese group (OR=2.56, 95% CI 2.38-2.76, P<0.001) than that in normal and low body mass group. The risk of hypertension in the obese group was 2.77 times (95% CI 2.40-3.21, P<0.001) and 2.66 times (95% CI 2.35-3.00, P<0.001) higher than that in the normal and underweight groups respectively in subjects with low high-density lipoprotein cholesterol (HDL-C) and high total cholesterol (TC). Restricted cubic spline analysis showed that after adjusting for confounding factors, the relationship between BMI and the risk of hypertension in elderly patients with dyslipidemia showed an approximately "S"-shaped relationship (non-linear test P<0.001). When BMI<24 kg/m², the risk of hypertension did not change significantly with BMI (OR=0.99, 95% CI 0.95-1.04, P=0.857); when BMI was 24-29 kg/m², the risk of hypertension increased with the increase of BMI (OR=1.11, 95% CI 1.06-1.16, P<0.001), while when BMI>29 kg/m², the risk of hypertension did not change significantly with BMI (OR=1.02, 95% CI 0.99-1.05, P=0.133). Conclusion There is a "S"-shaped relationship between BMI and the risk of hypertension in the elderly patients with dyslipidemia, when BMI is between 24 to 29 kg/m², the risk of hypertension increases with BMI, when BMI is below or above the threshold, the risk of developing hypertension does not vary with changes in BMI.