Abstract P011: White Blood Cell Count in Young Adulthood and Coronary Artery Calcification in Early Middle Age: Coronary Artery Risk Development in Young Adults (CARDIA) Study

Abstract

Background: White blood cell (WBC) count is associated with incident coronary heart disease (CHD). Coronary artery calcification (CAC) is a measure of subclinical atherosclerosis that predicts CHD events. Since data are sparse regarding the association of WBC count with future CAC, we examined the association of WBC count in early adulthood (age 18-30 yrs.) with the presence of CAC 15 or 20 years later (age 33-50 yrs.). Methods: We included CARDIA participants who had baseline data on risk factors and WBC counts, and participated in the Year (Y) 15 or Y20 examinations with CAC score information. We performed age-, sex-, and race-adjusted linear regression analyses to examine the cross-sectional association between baseline (Y0) WBC count (total and subtypes) and known CHD risk factors, including systolic blood pressure (SBP), BMI, smoking (packs/year), total and HDL-cholesterol. We used multiple logistic regressions to assess prospective associations between Y0 WBC count and the presence of CAC at Y15 and Y20. Results: Among 3094 participants, mean (SD) age at baseline was 25± 4 years, 57% were women and 45% were black. In total, 263 and 566 subjects had CAC score>0 at Y15 and Y20 examination, respectively. Y0 SBP, BMI, and smoking (p<0.001), and HDL-cholesterol (p=0.01) were significantly associated with Y0 total WBC counts. Compared to participants without CAC at Y20, those with CAC score>0 had higher Y0 counts (10 9 /L, SD) of total WBC (6.0 ± 1.8 vs. 6.2 ± 1.9, p=0.04), lymphocyte (2.16 ± 0.75 vs. 2.23 ± 0.76 p=0.05), and eosinophil (0.16 ± 0.13 vs. 0.18 ± 0.16, p<0.001). These counts were positively associated with the presence of Y20 CAC after adjusting for potential confounders ( Table 1 ). Similar patterns were observed for Y15 CAC (data not shown). Conclusion: Total WBC and certain subtype counts in young adulthood are significantly associated with presence of CAC 15 or 20 years later in early middle age. These findings suggest the possible involvement of WBC in the initiation and/or early development of atherosclerosis. Table 1. Y0 WBC counts and CAC presence at Y20 (OR (95% CI) per 1 x 10 9 /L WBC counts Model 1 * Model 2 ** Total WBC 1.24 (1.12, 1.37) 1.11 (1.00, 1.24) Monocyte 1.02 (0.93, 1.13) 0.96 (0.87, 1.07) Neutrophils 1.13 (0.99, 1.28) 1.06 (0.93, 1.21) Lymphocyte 1.16 (1.05, 1.28) 1.03 (0.93, 1.14) Eosinophil 1.17 (1.05, 1.29) 1.14 (1.02, 1.27) * Age, sex, race adjusted; ** Model 1 plus Y0 education, SBP, BMI, TC, HDL, smoking and blood pressure lowering medication use.