Risk for nonhemorrhagic stroke elevated among American Indian adults with, without AF
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American Indian adults experienced a 47% greater risk for nonhemorrhagic stroke compared with white, Black, Hispanic and Asian adults, researchers reported.
According to data published in the Journal of the American Heart Association, the increased risk was not accentuated by the presence of atrial fibrillation, and researchers suggested other factors such as genetics, environmental exposures or access to health care may be at play.
“In previous research, we have confirmed that American Indian individuals, when compared with those in other racial or ethnic groups, have the highest risk of atrial fibrillation, which is a quivering or irregular heartbeat that can substantially increase the risk of blood clots and stroke,” Gregory M. Marcus, MD, MAS, professor of medicine and associate chief of cardiology for research at the University of California, San Francisco, said in a press release. “While American Indian people are known to have a particularly high risk for stroke, in general, the relationship between AF and nonhemorrhagic, or nonbleeding, stroke among this group has not been thoroughly studied.”
For this analysis, researchers utilized data from the Healthcare Cost and Utilization Project to identify nearly 17 million adult residents of California who received care in an ED, inpatient hospital unit or ambulatory surgery setting from 2005 to 2011 (0.6% American Indian). Researchers evaluated the risk for nonhemorrhagic stroke among American Indians compared with white, Blacks, Hispanic and Asian residents.
After adjustment for age, sex, income, insurance, hypertension and other traditional CV risk factors, the researchers found American Indians experienced a 47% greater risk for nonhemorrhagic stroke compared with the other races/ethnicities (adjusted HR = 1.47; 95% CI, 1.4-1.55; P < .0001).
American Indians with AF experienced a 38% greater risk for nonhemorrhagic stroke compared with individuals of other races/ethnicities with AF (aHR = 1.38; 95% CI, 1.23-1.55; P < .0001).
Findings were similar among subgroups of California residents who were only admitted to EDs or inpatient hospital units and those older than 35 years with at least two encounters.
An interaction analysis found no relationship between presence of AF and risk for nonhemorrhagic stroke among individuals who are American Indian (HR without AF = 1.59; 95% CI 1.51-1.67; HR with AF = 1.39; 95% CI 1.24-1.57; P for interaction = .05).
“The results of our study add to the growing body of evidence that race and ethnicity are important factors when assessing stroke risk,” Marcus said in the release. “However, our findings that conventional risk factors such as AF may not be the cause for this increased risk among American Indian individuals suggest other influences are in play. These could possibly be related to hereditary factors, environmental exposures or disparities in access to health care, and this clearly warrants further attention.”
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