White blood cell count and the risk for coronary artery disease in young adults.

Background: The association between white blood cell (WBC) count and coronary artery disease (CAD) is unknown in young adults. Our objective was to assess the association between WBC count and its changes over time with CAD incidence in the Metabolic, Life-style and Nutrition Assessment in Young adults (MELANY) study, a cohort of Israeli army personnel.

Methods And Findings: 29,120 apparently healthy young men (mean age; 31.2±5.5 years) with a normal baseline WBC count (3,000-12,000 cells/mm(3)) were followed during a mean follow up of 7.5±3.8 years for incidence of CAD. Participants were screened every 3-5 years using a stress test, and CAD was confirmed by coronary angiography. In a multivariate model adjusted for age, body mass index (BMI), LDL- and HDL-cholesterol, blood pressure, family history of CAD, physical activity, diabetes, triglycerides and smoking status, WBC levels (divided to quintiles) above 6,900 cells/mm(3) (quintile 4) were associated with a 2.17-fold increase (95%CI = 1.18-3.97) in the risk for CAD as compared with men in quintile 1 (WBC≤5,400 cells/mm(3)). When modeled as a continuous variable, a WBC increment of 1000 cells/mm(3) was associated with a 17.4% increase in CAD risk (HR 1.174; 95%CI = 1.067-1.290, p = 0.001). A decrease in the WBC level (within the normal range) during the follow-up period was associated with increased physical activity and decreased triglyceride levels as well as with reduced incidence of CAD.

Conclusions: WBC count is an independent risk factor for CAD in young adults at values well within the normal range. WBC count may assist in detecting subgroups of young men at either low or high risk for progression to CAD.