Background: Women have generally lower levels of uric acid compared with men, yet their long-term prognostic impact is unclear in ischemic stroke patients. This study aims to investigate the significance of serum uric acid in relation to 5-year recurrent vascular events and mortality in ischemic stroke patients.
Methods: Consecutive patients with acute ischemic stroke were recruited from the National University Hospital, Singapore, between January 2011 and December 2012. Demographic, risk factor, stroke etiology and severity information were compared with the development of vascular events (defined as stroke, myocardial infarction, and vascular-related death) and all-cause mortality. Blood samples were collected during their acute hospitalization; in a subset of patients, repeated samples were collected 3-6 months later. Uric acid was measured in serum using the Cobas c111 analyzer (Roche, Germany). The effects of uric acid on vascular events and death were evaluated by Cox proportional hazard models.
Results: A total of 531 ischemic stroke patients (mean age 59.2 years; 72% men; mean uric acid 357 mmol/l [men], 319 mmol/l [women]) were followed for a mean of 3 years. During this period, 136 vascular events (72% stroke and transient ischemic attack, 18% myocardial infarction and 10% vascular-related death) and 51 deaths were recorded. In women, significant associations were observed between uric acid levels and vascular-related deaths and all-cause deaths (adjusted hazard ratios 1.01 [95% CI 1.00-1.01; p=0.008] and 1.01 [1.00-1.01; p=0.001] respectively); no association was observed with vascular events. By contrast, no significant association was observed between vascular-related events and deaths in men. 176 patients had uric acid levels repeated. Overall, there was an increase in uric acid levels (326 vs 360 mmol/l; p<0.001, paired t-test) approximately 4 months following stroke onset. These changes, however, did not correlate with subsequent development of vascular and death events in men and women.
Conclusions: In women, uric acid levels predict long-term vascular death and all-cause mortality in ischemic stroke patients. The sex-specific differences in the association between uric acid and stroke outcomes warrant further investigations.