Increasing prevalence of hypertension in Hong Kong Cardiovascular Risk Factor Prevalence Study: role of general and central obesity

Abstract

Introduction: General obesity and central obesity are well-known risk factors of hypertension. We investigated the change in the prevalence of hypertension in the population-based prospective Hong Kong Cardiovascular Risk Factor Prevalence Study (CRISPS) and the relationship of change in blood pressure with change in body mass index (BMI) and waist circumference over a follow-up period of 11.9 years. Methods: A total of 2888, 1942 and 1798 subjects in CRISPS-1 (1995-1996), CRISPS-2 (2000-2004) and CRISPS-3 (2005-2008) were included in this analysis respectively. Hypertension was defined as blood pressure ≥140/90 mm Hg or taking anti-hypertensive medication. General obesity was defined as BMI ≥27.5 kg/m2 and central obesity was defined as waist circumference ≥90 cm in men or ≥80 cm in women. Results: The prevalence of hypertension increased from 18.1% to 39.4% (P<0.001 after adjusting for age and sex). The prevalence of central obesity increased from 25.4% to 41.4%, but that of general obesity decreased from 16.8% to 14.8% (both P<0.001 after adjusting for age and sex). Among 1347 subjects who did not take any anti-hypertensive medication at both CRISPS-1 and CRISPS-3, the change in waist circumference, but not that in BMI, was associated with the changes in both systolic and diastolic blood pressures (beta=0.087, P=0.015 and beta=0.122, P<0.001 respectively). Conclusions: The increase in prevalence of hypertension might be explained by the increase in central obesity. Our findings further confirm the importance of waist circumference in this population; calculating the BMI alone may give a false sense of security. Acknowledgement: This study was funded by Hong Kong Research Grant Council grants (HKU7229/01M and HKU7626/07M) and the Sun Chieh Yeh Heart Foundation.