Leukocyte count is associated with incidence of coronary events, but not with stroke: A prospective cohort study

ObjectiveElevated leukocyte count is a classic marker of systemic inflammation. This study examined whether the leukocyte count is associated with incidence of coronary events (CE) and stroke during a long follow-up period.MethodsA total of 17,131 men and 2932 women, aged 27–61 years, without history of cardiovascular disease (CVD), were enrolled. Incidence of CE and stroke was studied in relation to leukocyte concentrations over a mean follow-up of 24 years.ResultsDuring the follow-up period, 2600 CE and 1333 stroke events occurred. After risk factor adjustments, leukocyte concentrations in the highest quartile (vs. lowest, >7.0 vs. <4.7 × 109 cells/L) were associated with CE in men (HR: 1.31, 95%CI: 1.16–1.48, trend p < 0.001), but not significantly in women (HR: 1.46, CI: 0.87–2.46, trend p = 0.13). The increased incidence remained significant after adjustments for plasma fibrinogen in a sub-group of 6018 men (HR: 1.31, CI: 1.08–1.60).The association between leukocytes and CE was most pronounced in younger men (aged 27–46) and men without hypertension. In younger men, high leukocytes were associated with early CE (within 10 years of follow-up) and late CE (>10 years of follow-up). In older men (46–61 years), leukocytes were not associated with CE after more than 10 years of follow-up.The leukocyte count was not associated with incidence of stroke.ConclusionElevated leukocyte count in men is associated with increased incidence of CE, but not with stroke. The increased risk persisted after more than 10 years of follow-up in younger, but not in older men.