he Seventh Report of the Joint National Committee (JNC-7) on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure in 2003 proposed a new classification for individuals between normal blood pressure (BP) and established hypertension. The report detailed that people with systolic BP (SBP) between 120 and 139 mmHg or diastolic BP (DBP) 80 and 89 mmHg were categorized as having 'prehypertension'. 1 Prehypertension tended to increase in severity over time. 2 Prehypertension progressed to clinical hypertension at a rate of 19% over 4 years. 3 The relationship between BP and risk of cardiovascular disease events was continuous and consistent. 4 Beginning at a SBP/DBP of 115/75 mmHg, the risk of cardiovascular disease was doubled with each increment of 20/10 mmHg. [5][6][7] Lifestyle modification or even medical treatment was recommended for individuals with prehypertension. 1 However, little was known about the epidemiology of prehypertension in the countryside of China when the report was released. We investigated rural adult people from 2004 to 2005 in Liaoning Province. The purpose was to determine the prevalence of prehypertension and associated risk factors in the rural adult people of China.
Methods
Study ParticipantsThe procedures followed were in accordance with ethical standards of the responsible committee on human experimentation of China Medical University. This investigation was based on a large-scale epidemiological study in a typical area of China with a cross-sectional survey that adopted a cluster multi-stage and random sampling method in Fuxin County, Liaoning Province. A total of 35,360 participants over 35 years age were in the survery area; however 29,970 individuals were examined between 2004 and 2005, with the response rate 84.8%. Associated factors included age, ethnicity, education, smoking, drinking, salt intake, lipid disorder, diabetes, body mass index (BMI) and waist circumference (WC). For most age-related comparisons, participants were separated into 4 groups according to age (35-44 years, 45-54 years, 55-64 years, ≥65 years). For ethnicity, on the basis of self-reported information, participants were grouped as Han people, Mongolian, and others. We chose to use people's reported education levels (high school) as the indicator of socioeconomic status. 8 Smoking habits were recorded and the term 'smoker' was considered if a person smoked at least 10 cigarettes every day. The weight and height of subjects were measured and BMI was calculated as weight (kg)/height (m) 2 . According to the World Health Organization criteria, BMI were categorized into 3 groups as normal (BMI <25), overweight (25≤ BMI <30) and obesity (BMI ≥30). WC was also measured. Salt intake was measured by investigating the total amount of salt consumed in a family for 1