Black and Hispanic people may be more likely to have another intracerebral hemorrhage or a stroke caused by bleeding in the brain, than white people, according to a study published in the June 6, 2018, online issue of Neurology®, the medical journal of the American Academy of Neurology.
Hemorrhagic stroke makes up only 10 to 15 percent of all strokes, but it is the deadliest and most disabling type of stroke. Once people have had a first stroke of this kind, they are at high risk of having another one, which is often fatal.
"Previous studies have shown that black and Hispanic people are at greater risk of having a first bleeding stroke, but studies have not looked at ethnic and racial differences in recurrent intracerebral hemorrhage," said study author Alessandro Biffi, MD, of Massachusetts General Hospital in Boston and a member of the American Academy of Neurology. "Since controlling high blood pressure is the main method of preventing second strokes and we know that there are racial and ethnic differences in the prevalence of high blood pressure and its severity, we really wanted to investigate these differences."
For the study, researchers combined results from two studies of people who had an intracerebral hemorrhage, for a total of 2,291 people. Of those 1,121 were white, 529 black, 605 Hispanic and 36 of other race/ethnicity. The participants' blood pressure readings were taken at the start of the study and at least once every six months after that. A total of 41 participants had previously had an intracerebral hemorrhage before the one involved in this study.
The 1,532 people in one study were followed for a year after the stroke and during that time 23 people had another stroke, for a recurrence rate of 1.5 percent. The 759 people in the second study were followed for an average of about four years. During that time 75 people had another stroke, for a recurrence rate of 3.9 percent.
Combining both studies, there were 26 second strokes among the 1,121 white people, or 1.7 percent, compared to 35 second strokes among the 529 black people, or 6.6 percent, and 37 among the 605 Hispanic people, or 6.1 percent. The researchers found that black people were more than twice as likely as white people to have another stroke and Hispanic people were about 70 percent more likely than whites to do so.
The average systolic blood pressure was higher for black and Hispanic people than for whites, with an average of 149 mmHg for black people, 146 mmHg for Hispanic people and 141 mmHg for white people. Systolic blood pressure of less than 120 mmHg is considered normal; pressure of 140 mmHg or more is considered high.
Once researchers adjusted the results for the blood pressure differences, they found that black people were still nearly twice as likely to have another stroke as white people and Hispanic people were about 50 percent more likely to have another stroke.
"The differences in blood pressure among these groups do not fully account for the differences in the risk of having another stroke," Biffi said. "More research is needed to determine the factors behind this disparity."
Limitations of the study include that the number of recurrent strokes was limited and that the study captured only long-term blood pressure changes, not day-to-day variations.