Leukocyte count and vascular risk in symptomatic intracranial atherosclerosis

Background: Few data exist about the prognostic value of serum white blood cell (WBC) count among patients with symptomatic cerebrovascular disease. We investigated the relationship between WBC count and vascular risk in patients with symptomatic intracranial atherosclerotic disease enrolled in the Warfarin-Aspirin Symptomatic Intracranial Disease (WASID) study. Methods: The relationships between baseline serum WBC count (categorized into quartiles) and both ischemic stroke alone and the combined endpoint of ischemic stroke, myocardial infarction or vascular death were evaluated using the log-rank test and Cox proportional hazards regression. Results: Compared with the quartile with the lowest WBC counts at baseline (<= 5.9 x 10(9)/l), WASID subjects in both upper WBC quartiles (7.3-8.8; >= 8.9 x 10(9)/l) were more likely to be younger (p= 0.022), diabetic (p = 0.013), on statin treatment (p = 0.015), or have higher mean body mass index (p = 0.015) and triglyceride (p = 0.0065) values. The rate of the primary endpoint was greater among WASID subjects in the upper two WBC quartiles compared with the lower two quartiles (28 vs. 16%, hazard ratio = 1.7; 95% CI = 1.2 - 2.5, p = 0.003). After adjusting for baseline factors found to be significantly related to the time of primary endpoint in multivariate analysis, both upper WBC quartiles (vs. lowest quartile) were independently associated with a greater risk for the primary endpoint (hazard ratio of 1.5; 95% CI = 1.06 - 2.2, p = 0.024). Conclusions: An elevated WBC count at study entry was associated with an increased risk of stroke and vascular death in patients with symptomatic intracranial atherosclerotic disease enrolled in the WASID trial. Copyright (c) 2007 S. Karger AG, Basel.