Docs stress stroke prevention

WASHINGTON – A new study confirms trends that have long been worrisome for clinicians who work with Native populations: American Indians appear to have a higher incidence of stroke compared to white and black Americans, and their first strokes tend to be more deadly. Given the dire data, health experts say it’s another big opportunity to talk about prevention.

The findings, published in “Circulation: Journal of the American Heart Association” Sept. 23, indicated that the stroke incidence rate was 679 per 100,000 person years for Native people.

Past studies in persons of similar age found the stroke incidence rate 306 per 100,000 person years for Caucasians and 607 per 100,000 person years for blacks.

During more than 13 years of followup, 306 of 4,507 participants suffered a first stroke, usually when in their mid-60s. Just as in whites and blacks, ischemic stroke – stroke caused by a blockage that cuts off blood supply to the brain – was more common than hemorrhagic or bleeding stroke, at a rate of 86 percent versus 14 percent.

None of the study’s participants, ages 45 to 74, had a history of stroke when they were recruited for the study from 1989 to 1992. Nearly 60 percent of the volunteers were women.

Among Indians age 18 and over, about 5.8 percent have had a stroke, compared to 3.4 percent of blacks and 2.3 percent among whites, according to data gathered by the American Heart Association/American Stroke Association.

The study is the largest longitudinal, population-based study of cardiovascular disease and risk factors among Indians to date. Researchers analyzed data from the Strong Heart Study, an observational study of adult members of 13 tribes living in southwestern Oklahoma, central Arizona, and North and South Dakota.

The research was funded by the National Heart, Lung and Blood Institute.

Ying Zhang, the study’s lead author and an assistant professor at the College of Public Health at the University of Oklahoma Sciences Center, said that first strokes appear to be more deadly in Indians. The death rate was approximately 18 percent within one month of stroke and 32 percent within one year of stroke.

Why the higher rates for Indians? Researchers cited a correlation of high rates of hypertension, diabetes and cigarette smoking in the Native population as possible reasons for the higher stroke incidence. They said each of the risk factors provides important avenues for intervention to reduce risk.

Researchers also found a high association between stroke and protein in the urine which is a marker for kidney dysfunction that is often associated with diabetes. They concluded that more studies of the association between kidney function and stroke incidences are needed.

They did not, however, find an association between alcohol use and stroke incidence in the studied group.

Greg Watson, a medical professional who has worked with several tribes, said he is “not at all” surprised by the study’s findings.

“We have known that stroke is a problem in the Indian population for a long time, and now we have some well-studied numbers to back it up,” he said.

“It’s yet another call for all of us to put on our prevention hats and really help younger Indians understand that they need to be out exercising and stopping bad habits, like cigarette smoking and eating high-fat foods.”

Laura Blackburn, another tribal health expert, said that it is much more difficult to reduce the risk of stroke once unhealthy behaviors are already part of a person’s routine.

“At that point, you’re already working from a deficit,” she said. “This is not to say that someone who has been unhealthy in the past can’t dramatically reduce their risk for a stroke. ... Still, it is more desirable to prevent the risk as early as possible.”

The Centers for Disease Control and Prevention lists several preventative steps that all people can take to lower their risk, whether they have had a stroke or not.

Top among them are preventing and controlling high blood pressure, high blood cholesterol and diabetes; not using cigarettes; treating atrial fibrillation (abnormal heart rhythm); moderating alcohol use; and maintaining a healthy weight through regular physical activity and a healthy diet.

Researchers involved with the study said clinicians who care for Indian patients should use the information to reduce their risk of stroke by providing appropriate treatment and by advising them to modify their lifestyle.