ANN ARBOR, Mich. -- The incidence of ischemic stroke -- the most common type of stroke caused by a clot in the blood vessels of the brain -- has declined over the past decade among non-Hispanic Whites and Mexican Americans over age 60.
The findings by the University of Michigan Health System were published today in the Annals of Neurology, a journal of the American Neurological Association and Child Neurology Society.
Despite the decline, the relative burden of stroke is unchanged and remains higher among Mexican Americans.
The stroke rate is 34 percent higher among Mexican Americans than non-Hispanic whites.
Hispanics/Latinos are now the largest minority group in the U.S. at 17 percent of the population, which is projected to increase to more than 30 percent by 2050, according to the U.S. Census.
Previous research found that Mexican Americans had higher stroke rates than non-Hispanic Whites, a trend that raises concern for the impact on public health as the population ages. Experts estimate that the cost of stroke for the first half of this century in the U.S. could amount to more than $1.5 trillion dollars.
"In minority groups stroke occurs at much younger ages, often resulting in greater disability and significantly higher costs," says lead study author Lewis B. Morgenstern, M.D., Director of the Stroke Program at the University of Michigan Health System. "With stroke causing such a personal, family and economic burden in minorities, our study focuses on Mexican Americans -- one of the largest and fastest growing segments of the U.S. population."
The study resulted from the only ongoing stroke surveillance project focusing on Mexican Americans. Since 2000, every stroke occurring in those age 45 and older living in Nueces County, Texas, has been counted and analyzed for the project Brain Attack Surveillance in Corpus Christi (BASIC).
BASIC is led by the University of Michigan Frankel Cardiovascular Center where researchers collaborate with a neurologist and study staff based in Corpus Christi, Texas. Together they examine the biological and social risk factors for stroke among Mexican Americans, information that may help reduce strokes and improve stroke care across the country.
Two-thirds of those in the study were Mexican American and the remainder primarily non-Hispanic White, with 87 percent born in the U.S., 11 percent in Mexico, and 1 percent who did not know their country of birth. Those born in Mexico have lived in the U.S. an average of 52 years.
Results show ischemic stroke occurred in 2,604 Mexican Americans and 2,042 non-Hispanic Whites, representing a 36 percent decline for the study period, 2000-2010.
Analysis found that the decline was limited to those age 60 and over and was evident in both ethnic populations. The large gap in stroke rates still remains among Mexican American and non-Hispanic White, ages 45-74.
"The dramatic decline in stroke rates during the last decade is encouraging," says Morgenstern, a professor of neurology, emergency medicine and neurosurgery at the U-M Medical School and professor of epidemiology at the U-M School of Public Health.
"However, the ongoing disparity among younger patients emphasizes the need for further interventions to prevent stroke, particularly among young Mexican Americans," he says.
Additional Authors: Melinda A. Smith, Brisa N. Sanchez, Devin L. Brown, Darin B. Zahuranec, Nelda Garcia, Kevin A. Kerber, Lesli E. Skolarus, William J. Meurer, James F. Burke, Eric E. Adelman, Jonggyu Baek and Lynda D. Lisabeth.
Reference: “Persistent Ischemic Stroke Incidence Disparities in Mexican Americans,” Annals of Neurology, Aug. 13, 2013 (DOI:10.1002/ana.23972).
Funding: This study was funded by National Institutes of Health National Institute of Neurological Disorders R01NS38916, NHLBI R01HL098065, and NINDS R01NS070941, NIH NIA K23AG038731, and NIH NINDS K23NS073685