Increasing prevalence of hypertension and central obesity in the Hong Kong cardiovascular risk factor prevalence study

Abstract

INTRODUCTION: Hypertension is known to be related to obesity. We studied the prevalence of hypertension over a period of 11.9 years in the population-based Hong Kong Cardiovascular Risk Factor Prevalence Study (CRISPS) cohort and investigated its association with changes in body mass index (BMI) and waist circumference. METHODS: A total of 2888, 1942 and 1798 subjects in CRISPS-1 (1995–1996), CRISPS-2 (2000–2004) and CRISPS-3 (2005–2008), respectively, were included in this analysis. Hypertension was defined as blood pressure ‡140/90 mmHg 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: An increase in the prevalence of hypertension was observed in the cohort, which might be explained by the increase in central rather than general obesity. Our findings further confirm the importance of measuring the waist circumference, as opposed to just calculating the BMI, in this population.