Middle-aged blacks are at higher risk for a first stroke, but not a second stroke

Although blacks in middle age (45-65) have three times the risk for a first stroke than whites of the same age, they don’t have a higher risk for subsequent strokes, according to a first-of-its-kind study published online January 20, 2016 in the journal Neurology.

“The interaction between black race and age appears to be remarkably different for the risk of first versus second stroke,” said study author George Howard, DrPH, Professor and Chair of Biostatistics at the University of Alabama at Birmingham School of Public Health, Birmingham, AL. “There was very little difference in race for the risk of a second stroke.”

The study began with 29,682 participants from the REasons for Geographic And Racial Differences in Stroke (REGARDS) study. Of this large cohort, 2,993 people at the start of the study had a history of stroke. Of these, 301 people had a second stroke during 7 years of follow up. In addition, 818 people had a first stroke during the study.

When researchers analyzed the data, they found that blacks were 2.7 times more likely than whites to have a first stroke by age 45; however, this disparity narrowed in older age such that, by age 85, blacks and whites have the same risk for a first stroke.

“However,” the authors wrote, “at younger ages, the apparent larger effect of a previous stroke on the risk of recurrent stroke in white than in black individuals is not because white individuals with a previous stroke have a much greater stroke risk than black individuals with a previous stroke, but rather that the risk of first stroke is substantially lower than the risk of first stroke among black individuals.”

In fact, race did not appear to increase risk for a second stroke in black participants at any age.

Other risk factors do play a role, though. “Almost all of the ‘traditional’ risk factors for a first stroke proved to also be a risk factor for a second stroke,” Dr. Howard said. “These risk factors include heart disease, high blood pressure, diabetes, smoking, irregular heartbeat, and others.”

This finding indicates that preventing and controlling these risk factors helps to avoid both primary and secondary strokes, the authors concluded.