White blood cell count as a risk factor for hypertension; a study of Japanese male office workers.
OBJECTIVE
To investigate the association of white blood cell (WBC) count with risk of hypertension.


METHODS
Cross-sectional and longitudinal studies.


METHODS
A work site in Japan.


METHODS
A total of 3776 Japanese male office workers aged 23-49 years were enrolled in this study; 2900 hypertension-free [systolic blood pressure (SBP) < 140 mm Hg, diastolic blood pressure (DBP) < 90 mm Hg, no medication for hypertension, and no past history of hypertension] men were followed up over a 4-year period.


METHODS
Blood pressure levels and the incidence of hypertension (SBP > or = 140 mm Hg and/or DBP > or = 90 mm Hg or medication for hypertension) according to WBC count at study entry.


RESULTS
After controlling for potential predictors of hypertension, SBP and DBP levels increased in a dose-dependent manner among both never-smokers and ex-smokers as WBC count increased. Among current smokers, only SBP level increased progressively with WBC count level. The multivariate-adjusted relative risk for development of hypertension compared with the first WBC count quintile was 1.29, 1.21, 1.67, and 1.92 among never-smokers (P for trend = 0.002): and 1.34, 1.46, 1.84, and 1.97 among ex-smokers (P for trend = 0.030) with the second, third, fourth, and fifth quintiles, respectively. Among current smokers, the respective multivariate-adjusted relative risks for hypertension relative to the first WBC count quintile were 0.91, 0.97, 1.08, and 0.84 (P for trend = 0.999).


CONCLUSIONS
WBC count is an important risk factor for hypertension, and the increased risk for hypertension associated with WBC count is more pronounced in non-smokers.
Nakanishi
Noriyuki
N
Department of Social and Environmental Medicine, Course of Social Medicine, Osaka University Graduate School of Medicine F2, Japan. noriyuki@pbhel.med.osaka-u.ac.jp
Sato
Mitsuru
M
Shirai
Kokoro
K
Suzuki
Kenji
K
Tatara
Kozo
K
D000328:Adult; D001794:Blood Pressure; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D006801:Humans; D006973:Hypertension / Q000453:epidemiology / Q000209:etiology*; D015994:Incidence; D007958:Leukocyte Count; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D012307:Risk Factors; D012907:Smoking; D016540:Smoking Cessation; D013599:Systole