Mexican Americans Have Higher Risk of Stroke Recurrence
Of the 700,000 people who have a stroke in the U.S. each year, roughly 200,000 have had one before. Recurrent strokes generally have worse outcomes and carry an increased risk of dying. Mexican Americans, the fastest growing segment of the U.S. population, have an increased risk of stroke compared to non-Hispanic whites, but the risk of recurrence and its effect on mortality has not been investigated until now. A study published in the September 2006 issue of Annals of Neurology, the official journal of the American Neurological Association examined stroke recurrence in Mexican Americans (MAs) and found that they had a higher risk compared with non-Hispanic whites (NHWs).
Led by Lynda D. Lisabeth, Ph.D., of the Department of Epidemiology at the University of Michigan, School of Public Health in Ann Arbor, MI, researchers identified stroke cases in Nueces County, TX as part of the BASIC project, a stroke surveillance project designed to study strokes in this isolated, urban community. From the beginning of 2000 until the end of 2004, researchers identified 1,345 patients who had their first stroke by analyzing hospital, nursing home and neurologists' records. A total of 53 percent of these patients were MA. They then identified those who had a recurrent stroke (126) and those who died of any cause following a first stroke (417).
"Recurrent stroke risk differed significantly by ethnicity," the authors state, "with MAs having higher recurrence risk." The differences seemed to be the largest for younger ages. In addition, stroke recurrence was significantly associated with risk of dying, but this was not affected by ethnicity.
Citing another study that showed that Hispanics of Puerto Rican heritage had almost a three-fold increased risk of recurrence compared with NHWs, the authors state "If future work confirms the current finding that Hispanics experience greater stroke recurrence risk compared with NHWs, factors contributing to ethnic differences should be investigated to improve outcomes following incident stroke." The current study also showed that those who had a recurrent stroke had a two to three-fold increased risk of death due to any cause. "The magnitude of this association was considerably larger than other predictors of death in this population including diabetes and coronary artery disease and indicates that in both ethnic groups, secondary stroke prevention is critical to improve survival following ischemic [inadequate blood flow] stroke," the authors state.
The authors note that the study did not examine whether there were differences in how traditional vascular risk factors, such as diabetes and hypertension, were handled in the two groups. "Differences in physician treatment, patient compliance, or differential drug effectiveness by ethnicity could also translate into increased stroke recurrence for MAs," they note. They add that it would be useful to investigate the rate of other vascular events following stroke and that this should be explored in future studies.
One interesting finding of the study was that MAs had better survival than NHWs following ischemic stroke, despite their increased risk of recurrence and the fact that recurrent stroke carried the same risk of dying in the two groups. The authors suggest that there may be unidentified factors that contribute to better survival in the MA population, such as better social support and/or genetic factors. Nonetheless, they suggest that efforts to reduce stroke recurrence in this population are needed.