Risk factors & prognosis for Stroke

Nonmodifiable risk factors for stroke

	Age: Exponential increase in risk with age
	Gender: men has greater stroke incidence, but woman lives longer, therefore outnumber men in total strokes
	Family history: first degree relative
	Race: Stroke mortality of African American is double that of White Americans.

Modifiable risk factors

Hypertension:

	Isolated systolic hypertension increases stroke risk by 2 to 4 times
	treatment of hypertension substantially reduces the risk of stroke by about 36% - 42%
	68% of persons are estimated to be aware of their hypertension, less than 30% are controlled
	Treatment recommendation

Cardiac diseases:

Nonvalvular atrial fibrillation (NVAF)

	36% of strokes in those between 80 and 89 years of age are attributed to NVAF
	Treatment Guideline

Valvular heart disease, myocardial infarction, coronary artery disease, congestive heart failure, ECG evidence of left ventricular hypertrophy

Diabetes mellitus

Hyperlipidemia: degree and progression of carotid atherosclerosis are directly related to cholesterol and LDL, inversely proportional to HDL. Treatment recommendation

Asymptomatic carotid stenosis:

	<75% stenosis, risk is 1.5%/year
	>75% stenosis, risk is 3.3%/year

Smoking:

	> 40 cigarette/day, stroke risk increases 2X
	cessation of cigarette smoking reduces the risk of stroke substantially within 2-5 years

Heavy alcohol consumption increase risk, light alcohol consumption may reduce stroke risk.

Transient ischemic attacks: average annual risk for stroke, MI, or death 7.5%/year.

Physical Inactivity: see lifestyle modification

Estimated outcome after ischemic stroke

Stroke evolution: 24% during hospitalization

Mortality

	30 day: 8-20%
	1 year: 15-25%
	5 year: 40-60%

Stroke recurrence:

	30 day: 3-10%
	1 year: 5-14%
	5 year: 25-40%

Functional disability: 24-53% of stroke survivors have complete or partial dependence

Dementia: 34% at 52 months post stroke

Further Reading

	Sacco RL. Risk factors, outcomes & stroke subtypes for ischemic strokes. Neurology 49:5. Nov 1997
	Gorelick, PB. Stroke Risk Factor modification. Am Academy of Neurology. Annual Meeting. 1999.

Treatment recommendation

Hypertension

Lifestyle modifications

	weight loss for those overweight
	limit alcohol intake to no more than 1 oz. ethanol per day (e.g.24oz. beer, 10 oz. wine, 2 oz. hard liquor per day or 0.5 oz ethanol per day for women and lighter weight persons)
	aerobic physical activity (e. 30-45 minutes of brisk walking most days of the week)
	reduce sodium intake to no more than 100mmol/d (2.4g sodium or 6g sodium chloride)
	maintain adequate dietary potassium intake (90mmol/d)
	maintain dietary calcium and magnesium for general health
	stop smoking and reduce dietary saturated fat and cholesterol for overall health benefit.

Pharmacologic treatment

	A diuretic and or a beta blocker are usually used as initial therapy
	Angiotensin converting enzyme inhibitors (ACE I) are the treatment of choice for patients with diabetes mellitus (unless contraindicated)
	ACE I and diuretics are first choice agents for patients with heart failure. ACE I are also recommended for patients with myocardial infarction and systolic dysfunction
	Beta-blockers without intrinsic sympathomimetic activity are used in patients with myocardial infarction.
	African Americans may respond better to monotherapy with diuretics and calcium antagonists than to beta-blockers or ACE I.
	Long-acting acting, once-daily dosing if possible.

Blood Lipids

Mean cholesterol levels increase until about age 64 years, after which they decline.

Recent observational studies have shown a positive association between lipids and ischemic stroke, and cholesterol levels and various subfractions have been linked to extracranial carotid stenosis, whereas HDL-cholesterol has been shown to be protective.

HMG-CoA reductase inhibitors reduce the risk of stroke in post-MI patients.

Pravastatin has been shown to reduce the risk of stroke in patients with previous MI & average cholesterol (< 240mg/dl) by about 31%

Simvastatin has been shown to reduce the risk of stroke and TIA in patients with previous myocardial infarction or angina pectoris and high cholesterol levels (5.5-8.0 mmol/l) by about 30% in post-hoc analysis.

FDA has approved these agents for stroke and TIA prevention in patients with CHD and 'average' or high cholesterol.

The findings generally apply to those < 70 years of age.

The benefit in patients with 'average' cholesterol raises speculation that the effect is mediated by some mechanism other than cholesterol lowering.

Treatment guideline

	LDL-C 130mg/dl, drug treatment is usually recommended
	LDL-C > 100mg/dl but < 130mg/dl, dietary treatment is recommended as the first treatment step.
	The goal is for LDL-C to be < 100mg/dl.