White blood cell count and cardiovascular disease. Insights from the Framingham Study

Abstract

Objective: To examine the relation of white blood cell (WBC) count to the development of cardiovascular disease (CVD), including coronary heart disease, stroke, peripheral arterial disease, and cardiac failure. Traditional CVD risk factors, hematocrit, and vital capacity were considered.

Design: Prospective cohort analysis with one baseline examination of relevant risk factors and 12 years of follow-up for CVD.

Participants and methods: A community-based sample (Farmingham Offspring Study) of 1393 men and 1401 women who were free of CVD at the onset of the study and who were between the ages of 30 and 59 years at baseline. Time-dependent multiple variable logistic regression methods were used.

Results: There were 180 CVD events in men and 80 in women. The WBC count was correlated most strongly with the number of cigarettes smoked per day, hematocrit, and vital capacity. Among nonsmoking men with WBC counts within the normal range, the age-adjusted WBC count was significantly associated with CVD and coronary heart disease incidence. For each 1.0 x 10(9)/L-cell difference in WBC count, the CVD risk increased 32%. In women, each 1.0 x 10(9)/L-cell increment in WBC count was associated with a 17% increase in CVD risk, but only in smokers, and the relationship was not statistically significant after adjustment for relevant risk factors.

Conclusions: The degree of elevation of WBC count within the normal range is a marker for increased risk of CVD that is partially explained by cigarette smoking. Future studies should include differential WBC determinations to assess their association with CVD.