Objective: Elevated 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.
Methods: A 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.
Results: During 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 x 10(9)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.
Conclusion: Elevated 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.
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