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Original Investigation
December 10, 2018

Sex and Race Differences in the Association of Incident Ischemic Stroke With Risk Factors

Author Affiliations
  • 1Department of Epidemiology, School of Public Health, University of Alabama at Birmingham
  • 2Department of Emergency Medicine, Alpert Medical School of Brown University, Providence, Rhode Island
  • 3Department of Neurology and Rehabilitation Medicine, University of Cincinnati College of Medicine, Cincinnati, Ohio
  • 4Department of Biostatistics, School of Public Health, University of Alabama at Birmingham
  • 5Epidemiological Cardiology Research Center, Department of Epidemiology and Prevention, Wake Forest University School of Medicine, Winston Salem, North Carolina
  • 6Department of Internal Medicine, Cardiology Section, Wake Forest University School of Medicine, Winston Salem, North Carolina
  • 7Department of Medicine, Weill-Cornell Medicine, New York, New York
  • 8Department of Health and Human Services, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland
  • 9Department of Epidemiology and Biostatistics, Dornsife School of Public Health, Drexel University, Philadelphia, Pennsylvania
  • 10Department of Medicine, Larner College of Medicine, Colchester, Vermont
JAMA Neurol. Published online December 10, 2018. doi:10.1001/jamaneurol.2018.3862
Key Points

Question  Are there sex differences in ischemic stroke incidence among black and white individuals or race-sex differences in the association of risk factors with stroke?

Findings  In this cohort study, among 25 789 black and white individuals in the United States, the ratio of stroke incidence rates between women and men was similar for black and white individuals across age groups, with women having lower stroke risk than men between 45 and 64 years of age and 65 and 74 years of age but similar risk at 75 years and older. For white individuals but not black individuals, the association of hypertension, diabetes, and heart disease with stroke risk differed by sex.

Meaning  Sex-specific risk factor management to prevent stroke may be needed for white individuals but not black individuals.

Abstract

Importance  Race-specific and sex-specific stroke risk varies across the lifespan, yet few reports describe sex differences in stroke risk separately in black individuals and white individuals.

Objective  To examine incidence and risk factors for ischemic stroke by sex for black and white individuals.

Design, Setting, and Participants  This prospective cohort study included participants 45 years and older who were stroke-free from the Reasons for Geographic and Racial Differences in Stroke (REGARDS) cohort, enrolled from the continental United States 2003 through 2007 with follow-up through October 2016. Data were analyzed from March 2018 to September 2018.

Exposures  Sex and race.

Main Outcomes and Measures  Physician-adjudicated incident ischemic stroke, self-reported race/ethnicity, and measured and self-reported risk factors.

Results  A total of 25 789 participants (14 170 women [54.9%]; 10 301 black individuals [39.9%]) were included. Over 222 120 person-years of follow-up, 939 ischemic strokes occurred: 159 (16.9%) in black men, 326 in white men (34.7%), 217 in black women (23.1%), and 237 in white women (25.2%). Between 45 and 64 years of age, white women had 32% lower stroke risk than white men (incidence rate ratio [IRR], 0.68 [95% CI, 0.49-0.94]), and black women had a 28% lower risk than black men (IRR, 0.72 [95% CI, 0.52-0.99]). Lower stroke risk in women than men persisted at age 65 through 74 years in white individuals (IRR, 0.71 [95% CI, 0.55-0.94]) but not in black individuals (IRR, 0.94 [95% CI, 0.68-1.30]); however, the race-sex interaction was not significant. At 75 years and older, there was no sex difference in stroke risk for either race. For white individuals, associations of systolic blood pressure (women: hazard ratio [HR], 1.13 [95% CI, 1.05-1.22]; men: 1.04 [95% CI, 0.97-1.11]; P = .099), diabetes (women: HR, 1.84 [95% CI, 1.35-2.52]; men: 1.13 [95% CI, 0.86-1.49]; P = .02), and heart disease (women: HR, 1.76 [95% CI, 1.30-2.39]; men, 1.26 [95% CI, 0.99-1.60]; P = .09) with stroke risk were larger for women than men, while antihypertensive medication use had a smaller association in women than men (women: HR, 1.17 [95% CI, 0.89-1.54]; men: 1.61 [95% CI, 1.29-2.03]; P = .08). In black individuals, there was no evidence of a sex difference for any risk factors.

Conclusions and Relevance  For both races, at age 45 through 64 years, women were at lower stroke risk than men, and there was no sex difference at 75 years or older; however, the sex difference pattern may differ by race from age 65 through 74 years. The association of risk factors on stroke risk differed by race-sex groups. While the need for primordial prevention, optimal management, and control of risk factors is universal across all age, racial/ethnic, and sex groups, some demographic subgroups may require earlier and more aggressive strategies.

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