Table 1.

Relative risks, odds ratios or hazard ratios of risk factors for stroke.

Risk factor	Type of study	Results	Reference
High blood pressure	Review	A close, progressive, and approximately linear relationship exists between BP levels and primary incidence of stroke	[5]
	Review of 45 observational cohorts involving 13,397 participants	A fivefold difference in stroke risk exists between the highest BP categories (usual DBP 102 mm Hg) and the lowest ones (usual DBP 75 mm Hg)	[6]
	Meta-analysis of 61 prospective observational studies	At ages 40–69, each difference of 20 mm Hg in usual SBP is associated with more than a twofold difference in the stroke death rate.	[7]
	Cohort studies involving 124,774 participants from 13 cohorts in China and Japan	Each 5 mm Hg lower usual DBP is associated with lower risk of both non-hemorrhagic (odds ratio 0.61, 95% CI 0.57–0.66) and hemorrhagic stroke (0.54, 0.50–0.58).	[8]
	National Health Survey of Pakistan	The relative risk comparing the hypertension group with the normal group is approximately 4.	[9]
Tobacco use	Cohort studies in US	In contemporary cohorts, male and female current smokers have similar relative risks for death from stroke (1.92 for men and 2.10 for women).	[10]
	Cohort study involving 202,248 participants in US	Adjusted hazard ratios for death from stroke among current smokers compared with persons who never smoked is 3.2 (99% CI, 2.2–4.7) for women and 1.7 (1.0–2.8) for men.	[11]
	Review	Current smokers have at least a two- to four-fold increased risk of stroke than lifelong nonsmokers or individuals who have not smoked for more than 10 years.	[12]
Diabetes mellitus	Review	People with diabetes have more than double the risk of ischemic stroke, relative to individuals without diabetes.	[13]
	Cohort study involving 3298 stroke-free participants in US	Compared to nondiabetic participants, those with diabetes for 0–5 years (adjusted HR, 1.7; 95% CI, 1.1–2.7), 5–10 years (1.8; 1.1–3.0), and more than 10 years (3.2; 2.4–4.5) are at increased risk of ischemic stroke.	[14]
Diet and Nutrition	Cohort study involving 174,888 participants in US	High consumption of fruits and vegetables is associated with lower risk of stroke. Adherence to the U.S. Department of Agriculture dietary recommendations for vegetable intake among women is associated with a reduced risk of fatal stroke, although this result is not statistically significant (relative risk, 0.84; 95% CI, 0.68–1.04).	[15]
	Cohort study involving 14,407 participants in US	Among overweight persons, a 100 mmol higher sodium intake is associated with a 32% increase (relative risk, 1.32; 95% CI, 1.07–1.64; P = 0.01) in stroke incidence, 89% increase (1.89; 1.31–2.74; P < 0.001) in stroke mortality.	[16]
	Cohort study involving 29,079 participants in Japan	Associations between sodium intake and death from ischemic stroke are significantly positive (hazard ratio, 3.22; 95% CI, 1.22 to 8.53).	[17]
Overweight and obesity	Cohort study involving 17,643 participants in US	Body mass index increases the risk of stroke not only through its impacts on other risk factors but also independently.	[18]
Physical activity	Meta-analysis of 18 cohort and 5 case–control studies	Highly active individuals have a 27% lower risk of stroke incidence or mortality (relative risk of 0.73; 95% CI, 0.67–0.79) than less-active individuals. Moderately active individuals compared with inactive persons (relative risks were 0.83 for cohort, 0.52 for case–control, and 0.80 for both combined).	[19]
Age	Cohort study involving 5201 participants in US	Risk of stroke approximately doubles for each successive decade of life after age 65.	[20]
Gender	Review	Women have more stroke events due to their longer life expectancy and older age at the time of stroke onset; stroke-related outcomes, including disability and quality of life, are poorer in women than in men.	[21]
	Systematic review of 98 articles	Stroke is more common among men, but women become more severely ill; incidence and prevalence rates of men are 33% and 41% higher, respectively, than those of women; stroke is more severe in women, with a case fatality at one month of 24.7% compared with 19.7% for men.	[22]
	Systematic review of 31 articles in Arab countries	Stroke is more common in males than females (range for males 55.9–75%).	[23]
Atrial fibrillation	Cohort study involving 5070 participants in US	In persons with coronary heart disease or cardiac failure, atrial fibrillation doubles the stroke risk in men and trebles the risk in women; in older patients ages 80–89, the attributable risk of stroke from atrial fibrillation is 23.5%.	[24]