Leukocyte Count as an Independent Predictor of Recurrent Ischemic Events

Abstract

Background and Purpose— Inflammatory markers predict first-time ischemic events. We investigated whether leukocyte and differential counts predict recurrent events and ischemic events in high-risk populations, and whether such events are preceded by acutely exacerbated inflammation. Methods— We studied 18 558 patients with ischemic stroke, myocardial infarction, or peripheral arterial disease who participated in the trial of Clopidogrel versus Aspirin in Patients at Risk of Ischemic Events (CAPRIE), a study that compared the occurrence of ischemic stroke, myocardial infarction, or vascular death under randomized treatment with aspirin or clopidogrel. Leukocyte counts were frequently assessed during followup. Results— Compared with the quartile with lowest leukocyte counts at baseline (8.2×10 ⁹ /L) had higher risks for ischemic stroke (relative risk 1.30; P =0.007), myocardial infarction (relative risk 1.56, P P 9 /L; P =0.005). Conclusions— Leukocyte counts and mainly neutrophil counts are independently associated with ischemic events in these high-risk populations. An increase of leukocyte counts over baseline levels heralds a period of increased risk lasting about one week.