White blood cell count: An independent predictor of coronary heart diseasemortality among a national cohort

An association between elevated white blood cell (WBC) count and coronary h eart disease (CHD) mortality has been previously observed. However, the rel ationship between WBC count and CHD mortality independent of cigarette smok ing and the possible interaction between WBC count and smoking remains uncl ear. We examined the association between WBC count and CHD mortality with C ox regression analyses of data from 8914 adults, aged 30-75, in the NHANES II Mortality Study (1976-1992). Covariates included age, sex, race, educati on, physical activity, smoking status, hypertensive status, total serum cho lesterol, body mass index, hematocrit, and history of cardiovascular diseas e, stroke, and diabetes. During 17 follow-up years, there were 548 deaths f rom CHD (ICD-9 410-414) and 782 deaths from diseases of the heart (ICD-9 39 0-398, 402, 404, 410-414, 415-417, 420-429). Mean WBC count (x10(9) cells/L ) was greater among persons who died from CHD (7.6 vs 7.2, P < .001). Compa red to persons with a WBC count <6.1, persons with a WBC count > 7.6 were a t increased risk of death from CHD (relative risk = 1.4, 95% confidence int erval = 1.1-1.8) after adjustment for smoking status and other CVD risk fac tors. Similar results were observed among nonsmokers (RR = 1.4, 95% CI = 0. 9-2.0). These results suggest that higher WBC counts are a predictor of CHD mortality independent of the effects of smoking and other traditional CVD risk factors, which may indicate a role for inflammation in the pathogenesi s of CHD. Additional studies are needed to determine whether interventions to decrease inflammation can reduce the risk for CHD associated with elevat ed WBC. (C) 2001 Elsevier Science Inc. All rights reserved.