Aim: This study aimed to investigate the associations of leukocyte count with the risks of stroke and coronary heart disease among the general Japanese population.
Methods: A total of 5,242 residents aged 40-69 years living in two Japanese communities underwent leukocyte count measurements between 1991 and 2000, and the data were updated using 5- or 10-year follow-ups or both. Participants who had histories of stroke, coronary heart disease, or high values of leukocyte count (＞130×102 cells/mm3) were excluded. Hazard ratios with 95% confidence intervals (CIs) were calculated according to quartiles of cumulative average leukocyte count.
Results: During follow-up of 21 years, 327 stroke and 130 coronary heart disease cases were determined. After adjustments for age, sex, community, and updated cardiovascular risk factors, the multivariable hazard ratio (95% CI) for the highest versus lowest quartile of leukocyte count was 1.50 (1.08-2.08) for ischemic stroke, 1.59 (1.00-2.51) for lacunar infarction, 1.42 (0.90-2.26) for non-lacunar infarction, 2.17 (1.33-3.55) for coronary heart disease, and 1.40 (1.11-1.76) for total cardiovascular disease. In smoking status-stratified analyses, the corresponding multivariable hazard ratio (95% CI) was 2.45 (1.11-5.38) for ischemic stroke, 2.73 (1.37-5.44) for coronary heart disease in current smokers, 2.42 (1.07-5.46), 1.55 (0.58-4.15) in former smokers, and 1.17 (0.75-1.82), 1.78 (0.83-3.82) in never smokers.
Conclusion: Leukocyte count was positively associated with the risks of ischemic stroke and coronary heart disease among the general Japanese population, especially in current smokers.
Keywords: Cohort study; Coronary heart disease; Ischemic stroke; Lacunar infarction; Leukocyte count.