American Indians Face the Highest Odds for Stroke

THURSDAY, March 4, 2021 (HealthDay News) -- While strokes strike many Americans, a new study shows the risk is particularly high among American Indians.

Researchers already knew that American Indians had the highest risk of atrial fibrillation, which is an irregular heartbeat ("arrhythmia") that can increase the risk of blood clots and stroke.

The new study found that American Indians had a 47% higher risk of having a non-bleeding stroke compared to people from all other racial and ethnic groups in the United States.

"Atrial fibrillation is the most common arrhythmia and one of the most common causes of stroke, and we now recognize likely an important determinant of other adverse consequences, such as dementia, heart attack and chronic kidney disease," said study author Dr. Gregory Marcus. He is associate chief of cardiology for research at the University of California, San Francisco.

"Although it's so common, the root causes of it remain a bit of a mystery, and we are in a period of transition and starting to think about atrial fibrillation as a preventable disease," Marcus said.

Unlike the well-known drug warfarin, which can be a hassle to take for atrial fibrillation, newer anticoagulants ("blood-thinning" drugs) don't require patients to change the dose, have routine blood test monitoring or change their diet, Marcus explained.

"These amazingly effective and safe drugs, and convenient-to-take drugs, are available for atrial fibrillation patients," he said. "However, that does not necessarily translate into atrial fibrillation patients actually having access to them, being prescribed them in the first place, or taking them."

Multiple interventions could help improve outcomes, but the easiest would be to enhance awareness of this heightened risk for stroke among this vulnerable population, Marcus suggested, with an eye toward making sure that doctors follow guidelines in prescribing these therapies.

In the study, the researchers reviewed the medical records of nearly 17 million U.S. adults who were treated in hospitals and other care settings in California from 2005 through 2011. The investigators followed their cases for a median of just over four years.

About 0.6% of the patients were American Indian, nearly 57% were white, 26% were Hispanic, about 9% were Asian and 8% were Black. During those four years, the patients experienced nearly 167,000 strokes, including close to 37,000 strokes in patients who were diagnosed with atrial fibrillation.

American Indians had a 38% higher stroke risk than other population groups who also had atrial fibrillation. Those who did not have atrial fibrillation had a 59% higher risk of stroke than other population groups, the researchers found.

The results add to the growing body of information that race and ethnicity are important factors when diagnosing stroke risk, Marcus said. Reasons for the higher risk for American Indians could include disparities in access to health care as well as hereditary factors and environmental factors, he noted.

In addition to having a higher risk of stroke, American Indians had lower rates of health insurance and lower income levels, as well as higher rates of type 2 diabetes, obesity and smoking, each of which ups stroke risk, according to the report.

The findings were published online March 2 in the Journal of the American Heart Association.

Marcus said the next step would be to conduct randomized trials among American Indian populations.

Larry Curley is executive director of the National Indian Council on Aging, an advocacy group with a mission to improve the socioeconomic health of older American Indians.

Curley said he agrees that more research is needed, including in other regions where there might be differences in risk.

"I know that the California tribes are different than, let's say, the Midwest tribes in Wisconsin or Minnesota [or] on the Plains, like North Dakota, South Dakota," Curley said. "So that would, to me, be a very illuminating study."

There are a number of reasons why American Indians might be facing greater stroke risk, Curley said, naming social determinants of health, lack of funding and also mistrust of the medical establishment because of abuses the tribal members have experienced at the hands of the establishment over the years.

"As a result, that distrust manifests itself in not trusting doctors," he said.

Curley also is concerned about a shortage of doctors in tribal areas and the quality of doctors working there.

He suggested establishing a medical school for American Indian doctors. A mentorship program that would recruit young people interested in medicine into the field is also needed, he added. Curley noted that research he has read shows that a majority of people who do their medical internships in rural areas stay in and continue to work in those areas.

"There are efforts by tribes around the country to, as they're saying, grow our own. I think if we can do that, that would be fantastic," Curley said. "I think existing teaching hospitals need to establish more of those kinds of teaching hospitals in communities or in cities that are close to Indian Country, so they can recruit those young doctors who are coming out of medical school so they can do their internships there."

More information

The U.S. National Library of Medicine has more on American Indian and Alaska Native health.

SOURCES: Gregory Marcus, MD, cardiologist, professor, medicine, and associate chief, cardiology for research, University of California, San Francisco; Larry Curley, MPA, executive director, National Indian Council on Aging, Albuquerque, N.M.; Journal of the American Heart Association, March 2, 2021, online