Clustering of cardiovascular risk factors and risk of development of hypertension in Japanese male office workers.

Abstract

Background: Obesity, hypercholesterolaemia, low high-density lipoprotein cholesterol levels, hypertriglyceridaemia, high fasting plasma glucose levels, hyperuricaemia and increased white blood cell count levels are all positively associated with the risk of hypertension, but the effect of the clustering of these risk factors on the risk for development of hypertension remains unclear.

Design: Longitudinal study at a work site in Osaka, Japan.

Methods: We examined 3784 Japanese male office workers aged 30 to 59 years who were hypertension-free [systolic blood pressure (SBP) < 140 mmHg, diastolic blood pressure (DBP) < 90 mmHg, no medication for hypertension, and no past history of hypertension]. Blood pressures were measured at annual health examinations from May 1996 to May 2001.

Results: After controlling for potential predictors of hypertension, the relative risk of hypertension (SBP>/=140 mmHg, DBP>/=90 mmHg, or both or prescription of antihypertensive medication) compared with the presence of no risk factors was 1.41 (95% CI, 1.21 to 1.64), 1.64 (95% CI, 1.38 to 1.96), 1.93 (95% CI, 1.56 to 2.39), 2.01 (95% CI, 1.51 to 2.68) and 3.34 (95% CI, 2.07 to 5.38) (P value for trend < 0.001) for respective risk factors of 1, 2, 3, 4 and >/=5. Even after the subjects were stratified according to blood pressure, the clustering of risk factors was associated with an increased risk of hypertension for subjects in all three categories of normotension: low-normal, normal, and high-normal.

Conclusions: Clustering of cardiovascular risk factors associated with hypertension precedes an increase in the risk of hypertension in Japanese men.