Background and purpose: We evaluated the impact of lifestyle factors on the risk of ischemic stroke.
Methods: We used a nested case-control design. The cases comprised 163 persons (median age 69 years) admitted to a stroke unit and diagnosed with acute cerebral infarction. All cases had earlier participated in the North Trøndelag Health Survey. The controls comprised 567 participants from the North Trøndelag Health Survey, matched by sex and year of birth.
Results: Raised systolic (p less than 0.001) and diastolic (p = 0.02) blood pressure, antihypertensive treatment (p less than 0.001), previous myocardial infarction (p less than 0.001), prior stroke (p = 0.002), diabetes (p less than 0.001), and former daily smoking (p = 0.02) were identified as significant risk factors by univariate conditional logistic regression. No difference in risk was detected at different levels of alcohol consumption, salt intake, physical activity, or body mass index. Current smokers had virtually the same risk as nonsmokers. No association was found between stroke and the number of cigarettes smoked per day or the number of years of smoking. Multivariate conditional logistic regression identified diabetes (p = 0.002), raised systolic blood pressure (p less than 0.001), and former daily smoking (p = 0.01) as significant and independent risk factors. Previous myocardial infarction (p = 0.07), previous stroke (p = 0.1), and current daily smoking (p = 0.1) were of marginal significance.
Conclusions: The established medical risk factors for stroke are confirmed. With the possible exception of smoking, we have not identified any lifestyle factor with a significant impact on the risk of ischemic stroke.