Relationship between body mass index and ischaemic stroke in Chinese elderly hypertensive patients

Background: Despite obesity being a major risk factor for ischaemic stroke (IS), the association between body mass index (BMI) and IS in patients with hypertension remains uncertain. Objective: To assess the association between BMI and IS among elderly hypertensive patients in China. Methods and results: We recruited 3500 hypertensive patients aged ≥60 between 1 January 2010 and 31 December 2011 in China and ascertained their stroke status until December 2016. Multivariate Cox regression was used to evaluate the association between BMI and IS with interaction tests for exposure and covariates. A total of 3315 subjects (mean age 71.41±7.20 years, 44.5% were men) were included for data analysis. During an average follow-up period of 5.5 years, there were 206 onset cases (6.21%) of IS. When BMI was treated as a continuous variable, it was positively associated with the incidence of new onset IS (HR=1.14; 95% CI: 1.05 to 1.34; p=0.005) after adjusting for potential confounders. Meanwhile, when BMI was treated as a categorical variable, the highest category (≥28 kg/m²) was strongly associated with an increased risk for IS compared with normal BMI category (18.5 to 24 kg/m²) (HR=1.36, 95% CI: 1.09 to 1.80; p<0.001) in the fully adjusted model. Subgroup and interaction analysis also demonstrated that BMI independently associated with IS among males, smokers, alcohol drinkers, diabetic patients, people with uncontrolled blood pressure, decreased estimated glomerular filtration rate and those aged ≥70 years. Conclusion: BMI was significantly associated with IS and was an independent risk of IS in Chinese elderly hypertensive patients.