White blood cell count and the incidence of ischemic stroke in coronary heart disease patients

PURPOSE: White blood cell (WBC) count is a marker of inflammation and has been associated with the development of cardiovascular disease. We investigated the relationship between WBC counts and the incidence of ischemic cerebrovascular disease in a large cohort of patients with pre-existing atherothrombotic disease and defined blood lipid boundaries. SUBJECTS AND METHODS: We followed up patients with documented coronary heart disease for 4.8 to 8.1 years. An extensive medical evaluation, conducted at baseline, included assessment of vascular risk factors and measures of blood lipids. Among 5435 patients with WBC counts, free of stroke, 295 developed an ischemic cerebrovascular disease (fatal and nonfatal). After review of available medical records, 186 of these cases had ischemic stroke or TIA. RESULTS: Higher WBC counts were associated with increased risk for ischemic cerebrovascular disease. Age-adjusted hazard ratio (HR) was 1.55 with 95% confidence interval (CI) 1.16-2.07, upper WBC tertile compared with the lowest. Adjusting for clinical covariates, WBC count remained an independent predictor for ischemic cerebrovascular disease (HR = 1.39; 95% CI 1.03-1.87, upper WBC tertile compared with the lowest). A similar trend appeared for the endpoint of ischemic stroke/transient ischemic attack (TIA). Further adjustment for plasma fibrinogen did not change the association materially (HR = 1.32; 95% CI 1.01-1.80; upper tertile of WBC compared with lowest). CONCLUSIONS: These findings support the role of WBC count as a simple inexpensive and readily available marker for risk stratification of ischemic cerebrovascular disease among patients with pre-existing atherothrombotic disease and defined blood lipid boundaries.