Abstract
BACKGROUND AND PURPOSE: Elevated plasma uric acid has been inconsistently associated with an increased risk of total stroke; however, data are sparse amongst women. The association between plasma uric acid concentrations and ischaemic stroke amongst women was examined and the effect modification by key cardiovascular risk factors was evaluated. METHODS: A nested case-control design with matching by age, race/ethnicity, smoking status, menopausal status, postmenopausal hormone therapy use, date of blood draw and fasting status was utilized amongst female participants of the Nurses' Health Study who provided blood samples between 1989 and 1990. Plasma uric acid was measured on stored blood samples. The National Survey of Stroke criteria were utilized to confirm 460 incident cases of ischaemic stroke by medical records from 1990 to 2006. Multivariable conditional logistic regression models were estimated. RESULTS: In matched analysis, risk of ischaemic stroke increased by 15% for each 1 mg/dl increase in plasma uric acid [95% confidence interval (CI) 3%-28%], but was no longer significant after adjustment for cardiovascular risk factors, particularly history of hypertension. The highest quartile of uric acid was significantly associated with greater risk of ischaemic stroke (relative risk 1.56; 95% CI 1.06-2.29, extreme quartiles) in matched analysis, but estimates were no longer significant after adjustment for cardiovascular risk factors (relative risk 1.43; 95% CI 0.93-2.18). Significant effect modification by key cardiovascular risk factors was not observed. CONCLUSIONS: Plasma uric acid levels were not independently associated with increased risk of ischaemic stroke in this cohort of women. Whilst plasma uric acid was associated with stroke risk factors, it was not independently associated with stroke risk.