A new study has found that long-term high systolic blood pressure (SBP) may be associated with an increased risk of stroke, particularly ischemic stroke and intracerebral hemorrhage. The study, which pooled data from 38,167 participants across six U.S. longitudinal cohorts, did not find consistent evidence that race and ethnicity modified the association between cumulative mean SBP and stroke risk.
Published in JAMA Network Open, the report calculated time-dependent cumulative mean SBP for each participant using repeated blood pressure measurements over a median follow-up period of 21.6 years. The study included participants from the Atherosclerosis Risk in Communities Study, Coronary Artery Risk Development in Young Adults Study, Cardiovascular Health Study, Framingham Offspring Study, Multi-Ethnic Study of Atherosclerosis, and Northern Manhattan Study.
The researchers adjusted their analyses for sociodemographic factors, vascular risk factors, and time-dependent antihypertensive medication use. They used multiple imputation to replace missing covariates at baseline and set statistical significance at a 2-sided P value of less than .05.
Over the follow-up period, 3,502 participants experienced a stroke, with ischemic stroke (83.3%) being more common than intracerebral hemorrhage (11.2%) and subarachnoid hemorrhage (2.7%).
A 10-mm Hg higher cumulative mean SBP was associated with a 20% higher risk of overall stroke (hazard ratio [HR], 1.20; 95% confidence interval [CI] 1.18-1.23), a 20% higher risk of ischemic stroke (HR, 1.20; 95% CI, 1.17-1.22), and a 31% higher risk of intracerebral hemorrhage (HR, 1.31; 95% CI, 1.25-1.38). The 13% higher risk of subarachnoid hemorrhage associated with a 10-mm Hg higher cumulative mean SBP was deemed as not statistically significant (HR, 1.13; 95% CI, 0.99-1.29; P = .06).
Compared with White participants, Black participants had a 20% higher risk of ischemic stroke (HR, 1.20; 95% CI, 1.09-1.33) and a 67% higher risk of intracerebral hemorrhage (HR, 1.67; 95% CI, 1.30-2.13), while Hispanic participants of any race had a 281% higher risk of subarachnoid hemorrhage (HR, 3.81; 95% CI, 1.29-11.22). However, the researchers found no consistent evidence that race and ethnicity modified the association between cumulative mean SBP and stroke risk.
"Our results suggest that cumulative mean SBP was a potent modifiable risk factor for stroke, ischemic stroke, and intracerebral hemorrhage," the authors wrote. "Our findings highlight the importance of providing culturally informed stroke prevention programs addressing modifiable risk factors such as blood pressure, along with social determinants of health and structural inequities in society."
The study's strengths include its large, diverse sample pooled from multiple cohorts, long follow-up period, and use of expert-adjudicated stroke outcomes. Limitations include the lack of adjustment for some socioeconomic factors and the small number of subarachnoid hemorrhage cases.
Complete ethics declarations are available within the study.