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INTRODUCTION: High blood pressure (BP) is a well-known major risk factor for cardiovascular diseases and is a leading contributor to cardiovascular mortality and morbidity worldwide. Reliable population-based BP data from low-middle income countries are sparse.

OBJECTIVE: This paper reports BP distributions among adults in nine rural populations in five Asian countries and examines the association between high BP and associated risk factors, including gender, age, education, and body mass index.

METHODS: A multi-site cross-sectional study of the major non-communicable disease risk factors (tobacco and alcohol use, fruit and vegetable intake, physical activity patterns) was conducted in 2005 in nine Health and Demographic Surveillance System (HDSS) sites in five Asian countries, all part of the INDEPTH Network. In addition to the self-report questions on risk factors, height and weight, and BP were measured during household visits using standard protocols of the WHO STEPwise approach to Surveillance.

RESULTS: In all the study sites (except among men and women in WATCH and among women in Chililab), the mean levels of systolic BP were greater than the optimal threshold (115 mmHg). A considerable proportion of the study populations - especially those in the HDSS in India, Indonesia, and Thailand - had high BP (systolic BP >/= 140 mmHg or diastolic BP >/= 90 mmHg or on treatment with BP medications). A more conservative definition of high BP (systolic BP >/= 160 mmHg or diastolic BP >/= 100 mmHg) substantially reduced the prevalence rate. The marked differences in the proportion of the populations on high BP medication (range between 0.6 and 10.8%) raised problems in comparing the prevalence of high BP across sites when using the commonly used definition of high BP as in this study. In the four HDSS in Bangladesh, women had a higher prevalence of high BP than men; the reverse was true in the other sites (Chililab, Filabavi in Vietnam; Kanchanaburi, Thailand; and Vadu, India) where men experienced higher prevalence than women. Overweight and obesity were significantly associated with high BP, with odds ratio ranging from two in Chililab to five in Filabavi (both in Vietnam HDSS).

CONCLUSION: The patterns of BP in these nine cross-sectional surveys were complex, reflecting the fact that the Asian countries are at different stages of the epidemiological transition. Actions to prevent the rise of BP levels are urgently required. An emphasis should be placed on cost-effective interventions to reduce salt consumption in the population as an immediate priority.