The effect of previous strokes on the relationship between ankle-brachial index determinations and incident strokes: A population-based, longitudinal prospective study in older adults

OBJECTIVE

Abnormal ankle-brachial index (ABI) determinations may be associated with an increased risk of incident strokes. However, the impact of previous strokes in this relationship is unknown. We estimated the role of previous strokes on the association between abnormal ABI determinations and incident stroke risk in community-dwelling older adults.

METHODS

Atahualpa residents aged ≥60 years received ABI determinations, cardiovascular risk factors assessment, and brain MRIs. ABIs were classified as abnormal if ≤0.9 or ≥1.4. Incident strokes were diagnosed by a certified neurologist with the aid of a post-event MRI. Poisson regression models were fitted to estimate stroke incidence rate ratio (IRR) according to categories of ABI.

RESULTS

Analysis included 389 participants (mean age: 68.2 ± 8.1 years). Eighty-six persons (22%) had abnormal ABI determinations. Incident strokes occurred in 38 (9.8%) individuals after a mean follow-up of 6.1 ± 1.9 years. Abnormal ABIs were associated with incident strokes in unadjusted analyses (p = 0.002) as well as in a Poisson regression model adjusted for demographics and clinical covariates (IRR: 2.57; 95% C.I.: 1.29-5.13), but not when the model was adjusted for neuroimaging covariates (IRR: 1.46; 95% C.I.: 0.67-3.20). Interaction models showed that having both abnormal ABI and non-lacunar strokes at baseline made the individual 9.7 times more likely to have an incident stroke (95% C.I.: 3.87-24.4). The risk was reduced to 2.2 (95% C.I.: 0.96-5.13) for those who only had an abnormal ABI.

CONCLUSIONS

An abnormal ABI is associated with a doubling the risk of incident strokes, but its importance is superseded by history of non-lacunar strokes.

Genetic Contributors of Incident Stroke in 10,700 African Americans With Hypertension: A Meta-Analysis From the Genetics of Hypertension Associated Treatments and Reasons for Geographic and Racial Differences in Stroke Studies

Background: African Americans (AAs) suffer a higher stroke burden due to hypertension. Identifying genetic contributors to stroke among AAs with hypertension is critical to understanding the genetic basis of the disease, as well as detecting at-risk individuals.

Methods: In a population comprising over 10,700 AAs treated for hypertension from the Genetics of Hypertension Associated Treatments (GenHAT) and Reasons for Geographic and Racial Differences in Stroke (REGARDS) studies, we performed an inverse variance-weighted meta-analysis of incident stroke. Additionally, we tested the predictive accuracy of a polygenic risk score (PRS) derived from a European ancestral population in both GenHAT and REGARDS AAs aiming to evaluate cross-ethnic performance.

Results: We identified 10 statistically significant (p < 5.00E-08) and 90 additional suggestive (p < 1.00E-06) variants associated with incident stroke in the meta-analysis. Six of the top 10 variants were located in an intergenic region on chromosome 18 (LINC01443-LOC644669). Additional variants of interest were located in or near the COL12A1, SNTG1, PCDH7, TMTC1, and NTM genes. Replication was conducted in the Warfarin Pharmacogenomics Cohort (WPC), and while none of the variants were directly validated, seven intronic variants of NTM proximal to our target variants, had a p-value <5.00E-04 in the WPC. The inclusion of the PRS did not improve the prediction accuracy compared to a reference model adjusting for age, sex, and genetic ancestry in either study and had lower predictive accuracy compared to models accounting for established stroke risk factors. These results demonstrate the necessity for PRS derivation in AAs, particularly for diseases that affect AAs disproportionately.

Conclusion: This study highlights biologically plausible genetic determinants for incident stroke in hypertensive AAs. Ultimately, a better understanding of genetic risk factors for stroke in AAs may give new insight into stroke burden and potential clinical tools for those among the highest at risk.

Serum Nonesterified Fatty Acids and Incident Stroke: The CHS

Background

Significant associations between total nonesterified fatty acid (NEFA) concentrations and incident stroke have been reported in some prospective cohort studies. We evaluated the associations between incident stroke and serum concentrations of nonesterified saturated, monounsaturated, polyunsaturated, and trans fatty acids.

Methods and Results

CHS (Cardiovascular Health Study) participants (N=2028) who were free of stroke at baseline (1996–1997) and had an archived fasting serum sample were included in this study. A total of 35 NEFAs were quantified using gas chromatography. Cox proportional hazards regression models were used to evaluate associations of 5 subclasses (nonesterified saturated, monounsaturated, omega (n)‐6 polyunsaturated, n‐3 polyunsaturated, and trans fatty acids) of NEFAs and individual NEFAs with incident stroke. Sensitivity analysis was conducted by excluding cases with hemorrhagic stroke (n=45). A total of 338 cases of incident stroke occurred during the median 10.5‐year follow‐up period. Total n‐3 (hazard ratio [HR], 0.77 [95% CI, 0.61–0.97]) and n‐6 (HR, 1.32 [95% CI, 1.01–1.73]) subclasses of NEFA were negatively and positively associated with incident stroke, respectively. Among individual NEFAs, dihomo‐γ‐linolenic acid (20:3n‐6) was associated with higher risk (HR, 1.29 [95% CI, 1.02–1.63]), whereas cis‐7‐hexadecenoic acid (16:1n‐9c) and arachidonic acid (20:4n‐6) were associated with a lower risk (HR, 0.67 [95% CI, 0.47–0.97]; HR, 0.81 [95% CI. 0.65–1.00], respectively) of incident stroke per standard deviation increment. After the exclusion of cases with hemorrhagic stroke, these associations did not remain significant.

Conclusions

A total of 2 NEFA subclasses and 3 individual NEFAs were associated with incident stroke. Of these, the NEFA n‐3 subclass and dihomo‐γ‐linolenic acid are diet derived and may be potential biomarkers for total stroke risk.

Transportation noise and risk of stroke: a nationwide prospective cohort study covering Denmark

BACKGROUND

Studies on transportation noise and incident stroke are few and inconclusive. We aimed to investigate associations between road-traffic and railway noise and the risk of incident stroke in the entire Danish population.

METHODS

We estimated road-traffic and railway noise (Lden) at the most and least exposed façades for all residential addresses across Denmark (2.8 million) for the period 1990-2017. Based on this, we estimated the 10-year time-weighted mean noise exposure for 3.6 million Danes aged >35 years, of whom 184 523 developed incident stroke during follow-up from 2000 to 2017. Analyses were conducted using Cox proportional-hazards models, with adjustment for various individual- and area-level demographic and socio-economic covariates collected from registries and air pollution [fine particulate matter with particles with a diameter of ≤2.5 µm (PM2.5) and nitrogen dioxide (NO2)].

RESULTS

A 10-dB increase in the 10-year mean road-traffic noise at the most exposed façade was associated with an incidence rate ratio (IRR) of 1.04 [95% confidence interval (CI): 1.03-1.05] for all strokes. For road-traffic noise at the least exposed façade, the IRR per 10 dB was 1.03 (95% CI: 1.02-1.04) for all strokes. Railway noise was not associated with a higher risk of stroke.

CONCLUSION

Road-traffic noise increased the risk of stroke. These findings add to the evidence of road-traffic noise as a cardiovascular risk factor.

Association between Body Mass Index and Stroke Risk Among Patients with Type 2 Diabetes

CONTEXT

Very few studies focused on the association between body mass index (BMI) and stroke risk among patients with diabetes.

OBJECTIVE

We aimed to investigate the association between BMI and stroke risk in patients with type 2 diabetes.

DESIGN

Demographic, anthropometric, laboratory, and medication information were extracted from the National Patient-Centered Clinical Research Network common data model.

PARTICIPANTS

We performed a retrospective cohort study of 67 086 patients with type 2 diabetes.

MAIN OUTCOME MEASURES

Incident stroke including both ischemic and hemorrhagic stroke were defined.

RESULTS

During a mean follow up of 3.74 years. 8918 incident stroke events occurred. Multivariable-adjusted hazard ratios across different categories of BMI at baseline (18.5-24.9 [reference group], 25.0-29.9, 30.0-34.9, 35.0-39.9, and ≥40 kg/m2) were 1.00, 0.92, 0.85, 0.74, and 0.63 (Ptrend <0.001) for total stroke; 1.00, 0.93, 0.88, 0.77, and 0.65 (Ptrend <0.001) for ischemic stroke; and 1.00, 0.79, 0.50, 0.50, and 0.41 (Ptrend <0.001) for hemorrhagic stroke, respectively. When we used an updated mean value of BMI, the graded inverse association of body mass index with stroke risk did not change. This linear association was consistent among patients of different subgroups. Further sensitivity analysis excluding patients who were diagnosed stroke within 6 months after first diagnosis of type 2 diabetes or including non-smokers only also confirmed our findings.

CONCLUSION

The present study found an inverse association between BMI and the risk of total, ischemic, and hemorrhagic stroke among patients with type 2 diabetes. More clinical and molecular insights are still needed in explaining these findings.

Total and differential white blood cell counts in late life predict 8-year incident stroke: the Honolulu Heart Program

OBJECTIVES

To study the association between total and differential white blood cell (WBC) count and incident stroke in an older Asian population.

DESIGN

Prospective population-based study with 8 years of follow-up.

SETTING

The Honolulu Heart Program, Oahu, Hawaii.

PARTICIPANTS

Japanese-American men aged 71 to 93 who were free of stroke and had baseline WBC counts measured in 1991-93 (N=3,342).

MEASUREMENTS

Participants were divided into quartiles of total and differential WBC count for analysis and were followed for incident stroke (thromboembolic and hemorrhagic (hemorrhagic)) for 8 years using data from a comprehensive hospital surveillance system.

RESULTS

Age-adjusted incident stroke rates increased significantly with increasing WBC quartile (Q1, 7.68; Q2, 9.04; Q3, 9.26; Q4, 14.10 per 1,000 person-years of follow-up, P=.001). Hazard ratios (HRs) for stroke for each quartile of total and differential WBC count were obtained using Cox regression analysis, with the lowest quartile as the reference group. After full adjustment, including age; cardiovascular risk factors; fibrinogen; prevalent coronary heart disease, cancer, or chronic obstructive pulmonary disease, and nonsteroidal anti-inflammatory drug use, HRs were 1.62 (95% confidence interval (CI)=1.04-2.52, P=.03) in the highest quartile of total WBC and 2.19 (95% CI=1.41-3.39, P<.001) in the highest quartile of neutrophil counts. Significant associations were also seen for thromboembolic but not for hemorrhagic strokes. No significant associations were found between lymphocyte or monocyte counts and incident stroke or subtypes.

CONCLUSION

In elderly Japanese-American men, higher total WBC and neutrophil counts were independent predictors of overall stroke, as well as thromboembolic stroke.