Association of white blood cell count with systolic blood pressure within the normotensive range

Hypertension and inflammation promote cardiovascular disease (CVD). Even high normal systolic blood pressure (SBP) is associated with increased CVD risk. We assessed the relationship of elevated SBP within the normotensive range and white blood cell (WBC) count. This is a cross-sectional study of 3484 white asymptomatic individuals (mean age: 43±8 years, 79% males) without hypertension with SBP < 140mm Hg. White blood cell count ≥75th percentile (8.35×10⁹ cells/l) was considered cutoff for elevated WBC. Subjects were classified into three levels of SBP (first: < 120mm Hg, n = 1176, 34%; second: 120-129mm Hg, n = 1654, 47%; third: 130-139mm Hg, n = 654, 19%). Mean WBC count increased linearly across SBP categories (first: 6.14 ± 1.54, second: 6.20 ± 1.52, third: 6.41 ± 1.62, P = 0.02 for trend). There was a linear increase in prevalence of elevated WBC across higher SBP categories (22, 24 and 28%, P = 0.02). As compared to those with SBP < 120mm Hg, in multivariate linear regression analyses (adjusting for age, gender, smoking status, diabetes, body mass index, physical activity, cholesterol/ high-density lipoprotein cholesterol ratio) WBC count was significantly higher among participants with SBP 130-139mm Hg (regression coefficient: 2.64, 95% confidence interval: 1.04-4.24, P = 0.001). Odds ratio for prevalence of elevated WBC with SBP <120mm Hg as reference group was 1.14 (0.92-1.41) for SBP 120-129mm Hg and 1.50 (1.15-1.92) for SBP 130-139mm Hg. In conclusion, Higher SBP within the normotensive range is also associated with elevated WBC count. Further studies are needed to clarify the role of inflammation in high normal SBP and associated CVD risk.