Risk factors for stroke in subjects with normal blood pressure: a prospective cohort study.
Although stroke is strongly associated with hypertension, some individuals with normal blood pressure (BP) experience a stroke. This prospective study explored risk factors for stroke in subjects with normal BP. A total of 11,228 men and 17,174 women, 45 to 73 years old, were examined in a population-based cohort study. Normal BP was defined as BP <140/90 mm Hg and no treatment for hypertension. The incidence of stroke was followed over a mean period of 6 years. In the cohort, 10,938 (38%) had normal BP. Of them, 56 patients experienced a first-ever stroke (12% of all stroke). Compared with subjects without stroke during follow-up, these stroke subjects were older, had lower education, were often smokers and alcohol nondrinkers, and had a history of coronary heart disease (CHD), gastric ulcer, or renal calculus. Subjects with stroke had a higher body mass index (BMI) and a high-normal BP (130 to 139/85 to 89 mm Hg) more often. In a backward stepwise Cox-regression analysis, age (per 1 year; relative risk [RR], 1.12), current smoking (RR, 3.21), BMI (per SD; RR, 1.39), high-normal diastolic BP (RR, 2.35), history of CHD (RR, 4.92), and gastric ulcer (RR, 2.21) remained significantly associated with incidence of stroke. In subjects with normal BP, there are a number of potentially modifiable risk factors associated with an increased incidence of stroke.