Elevated white blood cell count as a risk factor of coronary artery disease: inconsistency between forms of the disease.

White blood cells (WBC) destabilize coronary artery plaques and an elevated WBC count is a risk factor of coronary artery disease (CAD). Nevertheless, the differences between the forms of CAD in the relationship with WBC count remain to be elucidated. To study these differences, we reviewed the health-checkup records from 1994 to 1999 for 6021 Japanese post office workers without any cardiovascular abnormalities. Baseline WBC counts of patients with acute coronary syndrome (ACS) were significantly higher than those of subjects free from coronary artery discase (mean +/- SD = 9210 +/- 2703/microL vs 6205 +/- 1635/microL, P<0.001), while the patients with stable angina pectoris (sAP) (6233 +/- 1528/microL) were similar to subjects without coronary artery disease in baseline WBC counts. Hypertension at the baseline was related to sAP (relative risk [95% CI] = 61.78 [17.29 to 78.66]) but not to ACS. Conversely, hypercholesterolemia and cigarette smoking were risk factors for ACS (relative risk [95% CI] = 11.48 [2.39 to 18.03] and 10.04 [3.00 to 12.12], respectively) but not for sAP. Multivariate logistic regression analysis found only WBC count (1000/microL) discriminated between ACS and sAP (P=0.038, odds ratio 2.049 [1.042-4.016]). We conclude that an elevated WBC count may be a risk factor of ACS but not sAP, and this finding is consistent with previous reports demonstrating the effects of WBCs in the destabilization of coronary artery plaques.