Leukocyte Count and Risks of Stroke and Coronary Heart Disease: The Circulatory Risk in Communities Study (CIRCS).

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.