Ethnic Differences in Risk Factors for Ischemic Stroke

Abstract

Background and Purpose— The aim is to estimate the relative risk and population attributable risk (PAR) of risk factors for ischemic stroke by ethnic group. Methods— In this case–control study, cases of first ischemic stroke were taken from the South London Stroke Register and controls from a cross-sectional prevalence survey covering the same area. PAR was determined for each risk factor by ethnic group. Multivariable analysis was used to examine the association between risk factors and ischemic stroke across all ethnic groups. Results— 664 cases and 716 controls aged 45 to 74 years were included, with ethnicity of white 78%:42%, black Caribbean 16%:43%, and black African 6%:15%, respectively. For the white group, high PAR was found for ischemic heart disease (IHD) on ECG (56% [95% CI, 49% to 62%]), obesity (49% [95% CI, 40% to 56%]), hypertension (HT) (38% [95% CI, 29% to 46%]), smoking (31% [95% CI, 19% to 41%]), transient ischemic attack (TIA) (23% [95% CI, 19% to 27%]), and atrial fibrillation (AF) (16% [95% CI, 10% to 21%]). In the black Caribbean compared with the white group, PAR was higher for HT (46% [95% CI, 21% to 63%]) and diabetes mellitus (DM) (29% [95% CI, 14% to 42%]), and lower for current smoking (18% [95% CI, 1% to 32%]) and AF (10% [95% CI, 0% to 18%]). In the black African group HT had a higher PAR (59% [95% CI, 91% to 82%]) than the other groups. PAR for AF (11% [95% CI, −11% to 29%]), obesity (30% [95% CI, −20% to 60%]), and DM (4% [95% CI, −25% to 26%]) was low compared with the other groups. In multivariable analysis, risk factors associated with ischemic stroke included TIA, AF, IHD on ECG, smoking, excess alcohol, obesity, HT, and DM. Conclusion— In the first European case-control study examining risk factors for ischemic stroke in black Caribbean and African populations, some differences were demonstrated in the impact of risk factors between these groups. It may be important to address such differences when developing stroke preventative strategies.