Risk factors for first-ever stroke in the EPIC-Norfolk prospective population-based study

Abstract

Background: Many studies examining stroke risk factors have focused on men and younger age groups. We examined stroke risk factors over a wide age range including elderly and women in a British population.

Methods: We examined the prospective relationship between known risk factors for stroke and stroke incidence in 22 516 men and women aged 40-79 years without stroke at baseline in the years 1993-1997 participating in the European Prospective Investigation into Cancer-Norfolk.

Results: During a total of 214 542 person-years of follow-up, 507 incident strokes occurred (fatal=162). Stroke risk increased with increasing age [relative risk (RR) 1.65, 95% confidence interval: 1.54, 1.75 per increase in 5 years]. Our results confirm the importance of modifiable risk factors for stroke in men and women, in particular, blood pressure and smoking. Higher systolic blood pressure of 10 mmHg was associated with RR of 1.19 (1.13, 1.24) and current smokers had RR of 1.70 (1.29, 2.23) compared with never smokers independent of age, sex, body mass index, cholesterol, triglycerides and diabetes. Having a systolic blood pressure greater than 140 mmHg compared with less than 140 mmHg was equivalent to being 6 years older and current smoking compared with nonsmoking equivalent to being 5 years older and diabetes 5 years older in terms of stroke risk.

Conclusion: Classical modifiable stroke risk factors, blood pressure and smoking, may have a substantial impact on the age-related increase in stroke risk in men and women.