May 4, 2006 — The American Heart Association (AHA)/American Stroke Association (ASA) have issued a 2006 update of their 2001 guidelines on primary stroke prevention. These guidelines are published in the May 4 Rapid Access issue of Stroke: Journal of the American Heart Association.
The new report includes several recommendations regarding the identification and modification of stroke risk factors. The writing group, led by Larry B. Goldstein, MD, with the Duke University Medical Center, in Durham, NC, reviewed several lines of evidence and conducted a systematic literature review of new reports from 2001 to January 2005.
While the death rate from stroke has declined by about 18.5% since 1993, the annual incidence of stroke, which afflicts about 700 000 people a year in the United States, has declined by less than 1%, according to information in an AHA written release.
Risk factors and markers for a first stroke were classified according to their potential for modification (nonmodifiable, modifiable, or potentially modifiable) and strength of evidence (well-documented or less well-documented).
According to the report, nonmodifiable risk factors include age, sex, race/ethnicity, and family history. As was previously known, stroke is more likely to affect the elderly, men, African Americans, and people with a family history of stroke.
In addition, data published since 2001 suggest that low birth weight is also a potential nonmodifiable risk factor; adults born with a birth weight of 2500 g or less are at more than twice the risk for stroke compared with those with a birth weight of less than 4000 g, according to the report, although the reason for this relationship remains unclear.
Modifiable risk factors cited by the report include high blood pressure, smoking and passive smoking, lack of physical activity; and inadequate treatment of atrial fibrillation, carotid artery disease, and heart failure.
The guidelines recommend the use of a risk assessment tool, such as the Framingham Stroke Profile, to assess stroke risk. In addition, the report suggests that patients with rare genetic causes of stroke should be referred for genetic counseling, and high-risk patients with diabetes should be treated with statins.
In addition, the report recommends that transcranial Doppler ultrasound screenings should be conducted in children with sickle cell anemia at age 2 years, and transfusion therapy should be considered for those found to be at high risk for stroke. Adults with sickle cell anemia also should be assessed for known stroke risk factors, the report suggests.
Sleep apnea newly was cited as a potentially modifiable risk factor for stroke. Other less well-documented and potentially modifiable risk factors mentioned include the metabolic syndrome, alcohol use, illicit drugs, and use of oral contraceptives (OCs) in female smokers.
"We know that treating sleep apnea is associated with a reduction of blood pressure," Dr Goldstein noted in a written release. "And although we don't have direct evidence that treating sleep apnea will reduce stroke risk, the feeling is that it will. But that is not yet supported by randomized trials."
The guidelines also listed various other emerging risk factors for stroke, including inflammation, infection, and migraine.
Nutritional factors associated with stroke suggested that higher potassium and lower sodium may benefit patients perhaps "through mechanisms that are independent of blood pressure." In addition, recommendations to "meet current guidelines for daily intake of folate (400 µg/d), B6 (1.7 mg/d), and B12 (2.4 µg/d) by consumption of vegetables, fruits, legumes, meats, fish, and fortified grains and cereals (for nonpregnant, nonlactating individuals) may be useful in reducing the risk of stroke," the report indicates.
With regard to the use of low-dose aspirin, women whose risk is sufficiently high for the benefits to outweigh the risks may benefit from this approach. However, the evidence is not strong enough to recommend aspirin in men at high risk for stroke, according to the guidelines.
Other recommendations included the use of prophylactic carotid endarterectomy surgery by a surgeon with a low complication rate for asymptomatic patients with severe carotid blockage and avoidance of using hormone therapy (with estrogen, with or without progestin) for the primary prevention of stroke.
Stroke. Posted online May 4, 2006.