Obesity linked to increased stroke risk
Obesity is a key risk factor for coronary heart disease, but its relationship with cerebrovascular disease is perhaps less clear. A Finnish prospective cohort study set out to address this by looking at the association of different markers of obesity with the incidence of stroke.
The study included 49,996 patients, aged 25-74 years, with no history of coronary disease or stroke.
Participants were followed up for 19.5 years. The primary aim was to correlate various measures of obesity, including body mass index (BMI), waist circumference and waist:hip ratio, with the incidence of stroke.
During the follow-up 3,228 patients had a stroke, of which 2,554 were ischaemic and 674 haemorrhagic. The results were adjusted for confounding factors such as age, smoking, physical activity, educational level, family history of stroke, alcohol, blood pressure and cholesterol.
In comparison with the normal weight group (BMI 18.5-24.9) there was a clear and significant association with increasing weight and the incidence of total and ischaemic stroke, with the greatest incidence seen in the obese group (BMI >30). This finding occurred in both men and women.
The results were less clear-cut when looking at abdominal obesity. The incidence of total and ischaemic stroke increased in the higher quartiles of waist circumference and waist:hip ratio in men, but not in women.
Haemorrhagic stroke did not share these associations, although there was some evidence of a U-shaped curve in women, with increased incidence in the leanest and most obese patients.
Obesity seems to confer similar risks for developing thromboembolic cerebrovascular disease as it does with coronary disease – at least when BMI is used as the defining parameter. Abdominal obesity confers risk of stroke for men, but not for women.
Such studies add further support to global risk reduction strategies for all forms of cardiovascular disease.
Hu G, Tuomilehto J, Silventoinen K et al. Body mass index, waist circumference, and waist-hip ratio on the risk of total and type-specific stroke Arch Intern Med 2007;167:1420-7Reviewer
Dr Peter Savill
GPSI Cardiology, Southampton