Abstract P212: Elevated Uric Acid Levels and Risk of Ischemic Stroke among Women
Introduction: Elevated uric acid has been inconsistently associated with a moderately increased risk of total stroke; however the data are sparse among women. Previous studies have failed to address variation by cardiovascular disease (CVD) risk factors and differentiate between stroke types. We aimed to examine the association between uric acid levels and ischemic stroke among women and evaluate effect modification by key CVD risk factors.
Methods: The relationship between uric acid and ischemic stroke was examined using a nested case-control design among female participants of the Nurses’ Health Study who provided blood samples. Uric acid was measured on blood samples collected and stored between 1989-1990. The National Survey of Stroke criteria were utilized to confirm 460 incident cases of ischemic stroke by medical records from 1990-2006. Controls were matched to each case by age, menopausal status, hormone therapy use, ancestry, date of blood draw and smoking status. Multivariable conditional logistic regression models adjusted for BMI, physical activity, alcohol intake, estimated glomerular filtration rate, diabetes and heart disease. The influence of hypertension, total/HDL cholesterol and CRP were examined separately. Significance of effect modification by key risk factors was estimated using likelihood ratio tests.
Results: Significant partial spearman correlations, adjusted for matching factors, were found between uric acid and BMI (r=0.32; p<0.001), triglycerides (r=0.32; p<0.001), total/HDL cholesterol ratio (r=0.30; p<0.001) and C-reactive protein (CRP-r=0.26; p=<0.001). Five percent of controls exhibited hyperuricemia (uric acid>6.8). In matched analysis, the highest quartile of uric acid was significantly associated with greater risk of incident ischemic stroke (Q4 vs. Q1-OR:1.56; 95% CI:1.06-2.29); estimates were elevated but no longer statistically significant after adjustment for CVD risk factors (Q4 vs. Q1-OR:1.42; 95% CI:0.93-2.16). Hyperuricemia (<6.8 vs. >6.8 mg/dL) was significantly associated with risk of stroke in matched (OR=2.06; 95% CI:1.17-3.61) and multivariable analyses (OR=1.92; 95% CI:1.07-3.46). Additional adjustment for hypertension further attenuated the results (OR=1.68; 95% CI:0.92-3.04), as did adjustment for total/HDL cholesterol and CRP (OR=1.67; 95% CI:0.92-3.03). We did not observe significant effect modification of the association between uric acid and key CVD risk factors (age, hypertension, diuretic treatment, BMI, smoking, CRP and postmenopausal hormone use).
Conclusions: There was suggestive evidence for an association between elevated uric acid levels and greater risk of ischemic stroke in this population of women. Estimates were attenuated and no longer significant after adjustment for hypertension, suggesting the association may be mediated in part by history of hypertension.
- © 2013 by American Heart Association, Inc.