Although the incidence and mortality of stroke have been declining since the 1960s, stroke remains the third most common cause of death, after heart disease and cancers. This decline is likely related to reductions in risk factors, mainly cessation of smoking and treatment of hypertension.

Because of population increases, especially among the elderly, absolute numbers of strokes and stroke-related deaths have nevertheless increased. An estimated 750,000 people in the United States experience stroke each year (recurrent in about 10%), and more than seven times that figure, approximately 4.4 million, have experienced stroke before and are at varying risk of developing epilepsy.

Stroke incidence and mortality are similar among men and women, but because of differences in age distribution, 60% of stroke deaths occur in women. Incidence and mortality are also higher among African Americans than European Americans, with only about two-thirds of this difference accountable by differences in cardiovascular and socioeconomic risk factors. Age-adjusted mortality per 100,000 people is 61.5 for white men, 57.9 for white women, 88.5 for black men, and 76.1 for black women.31,32

In the United States, there are also regional differences in stroke incidence, which is highest in the southeastern United States (the “Stroke Belt”) and lowest in the southwestern and highly populated northeastern states.

Worldwide, there are large variations in incidence and mortality, with several countries of Eastern Europe having the highest rates. Among Asians, including Asian Americans, stroke incidence is high, especially in relation to relatively lower cardiovascular morbidity and mortality. This group also includes a higher proportion (about one-third) of hemorrhagic strokes relative to ischemic strokes. Also, large artery stenosis more commonly involves intracranial rather than extracranial vessels in both Asian Americans and African Americans than in European Americans.

In addition to age, hypertension (systolic and diastolic), smoking (for hemorrhage, as well as ischemia), and ethnic and regional differences, other risk factors for ischemic stroke include previous stroke, heart disease, and diabetes.31 Evidence for hypercholesterolemia as a risk factor is mixed, although recent studies suggest a benefit of statin-type cholesterol-lowering agents; these may have other effects in addition to lowering cholesterol, such as altering endothelial surfaces. Interestingly, low cholesterol has been associated with an increased incidence of hemorrhagic strokes, especially when combined with hypertension. Obesity is associated with several other risk factors, and any independent effect is likely to be small. Cancer, especially adenocarcinoma, predisposes to hypercoagulable states. Family history may elevate risk by approximately 50%, apart from other risk factors, and may be decisive in a minority of individuals with intracranial aneurysms and vascular malformations or inborn coagulation anomalies predisposing to bleeding or clotting. Risk of ischemic stroke also increases with blood levels of fibrinogen, homocysteine, and hematocrit, even within the normal range. Lack of exercise also increases risk of ischemic stroke, in addition to being linked to other risk factors, such as heart disease. Moderate alcohol use may be somewhat protective against ischemic stroke, but heavy use definitely increases the risk of hemorrhage. Among women, high-dose oral contraceptives increase risk of ischemia, especially when combined with smoking and older age; this combination is also associated with subarachnoid hemorrhage.31 Heart disease is a marker for atherosclerosis predisposing to stroke and is an independent risk factor for embolic disease. Atrial fibrillation is a widely recognized risk. Other heart conditions that are also significant include myocardial infarction, especially of the anterior wall; congestive heart failure; left ventricular hypertrophy; and patent foramen ovale.

Adapted from: Bromfield, EB, and Henderson GV. Seizures and cerebrovascular disease. In: Ettinger AB and Devinsky O, eds. Managing epilepsy and co-existing disorders. Boston: Butterworth-Heinemann; 2002;269–289.
With permission from Elsevier (www.elsevier.com). 

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Reviewed By: 
Steven C. Schachter, MD
on: 
Wednesday, March 31, 2004