Prognostic value of elevated white blood cell count in hypertension

Chronic low-grade inflammation may contribute to vascular injury and atherogenesis, and has been described in association to high blood pressure (BP). However, as yet the prognostic significance of white blood cell (WBC) count in the setting of uncomplicated hypertension has not been investigated.

In the Progetto Ipertensione Umbria Monitoraggio Ambulatoriale (PIUMA) study, 1617 white patients with essential hypertension (aged 49 +/- 12 years, 55% men) without prevalent cardiovascular or renal disease underwent off-treatment baseline clinical evaluation and were then followed up for 11 years (average 4.9 years).

The WBC count had a direct association with smoking status, serum triglycerides, body mass index, and 24-h BP, and an inverse one with age (all P < .05). During follow-up, 146 patients developed a major fatal or nonfatal cardiovascular event (1.9 events per 100 patient-years). Patients who will develop a cardiovascular event had a higher WBC count (7.08 +/- 1.6 v 6.68 +/- 1.6 x 10(9) cells/L, P = .004). Event rate increased progressively from the first to the fourth quartile of WBC count distribution (1.2, 1.8, 1.9, and 2.3 events per 100 patient-years; P < .01 by log-rank test). After adjustment (Cox model) for the effect of age, gender, diabetes, serum cholesterol, glomerular filtration rate, smoking, left ventricular hypertrophy, and 24-h systolic BP, cardiovascular event risk increased by 24% (95% confidence interval +4% to +48%; P = .019) for each 2 x 10(9) cells/L increase in WBC.

After adjustment for average 24-h BP, established risk factors and target organ damage, an elevated WBC count remains an independent predictor of cardiovascular morbidity in hypertensive patients.