How do the risk factors for ischemic and hemorrhagic stroke contrast and compare? What risk factors are the strongest predictors?
Stroke is the third leading cause of death and the leading cause of disability in the United States. Stroke and transient ischemic attack affect approximately 700,000 people each year. (1) The 3 major subtypes of stroke are ischemic stroke, intracerebral hemorrhage (ICH), and subarachnoid hemorrhage (SAH), and each has multiple pathophysiologic mechanisms. Ischemic stroke may be caused by small-vessel lipohyalinosis, extracranial carotid atherosclerosis, cardioembolism, and hypercoagulable disorders. Causes of ICH include hypertension and cerebral amyloid angiopathy, and causes of SAH include cerebral aneurysm and arteriovenous malformation. In general, stroke risk increases with advancing age and occurs at a higher rate among men than women and among African Americans and Hispanic persons than white persons. (2-4) The exception is SAH, which tends to occur more often in young women. (3)
Hypertension is the most important modifiable risk factor for all 3 subtypes of stroke. (4-6) Treatment has been found to reduce the overall risk of disease by approximately 34%. (7) Evidence has suggested that angiotensin-converting enzyme inhibitors, in particular, may reduce the risk of recurrent stroke. (8)
While cigarette smoking is a strong risk factor for coronary artery disease (CAD), it is an even stronger risk factor for SAH: nearly 70% of cases occur in current or former smokers. (5) While smoking has been associated with ischemic stroke, there is evidence that smoking may particularly contribute to large-vessel (extracranial carotid or intracranial atherosclerotic) ischemic stroke. (9) The connection between smoking and ICH is controversial, with several large, population-based studies finding no association between them. (6,10)
Frequent alcohol use (more than 2 drinks per day) has been identified consistently as an important risk factor for both SAH and ICH....