Prevalence and Risk Factors of the Rural People on Prehypertension Status in Lanxi County of Heilongjiang Province

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Author: Lili LING, Jingbo ZHAO, Shiying FU, Yujuan ZHAO, Fuman WANG, Liting YANG, Lihang DONG

Prevalence and Risk Factors of the Rural People on Prehypertension Status in Lanxi County of Heilongjiang Province Lili LINGa, Jingbo ZHAOa,*, Shiying FUb,*, Yujuan ZHAOa, Fuman WANGa, Liting YANGa, Lihang DONGa a Department of Epidemiology, School of Public Health, Harbin Medical University, Harbin, 150081, PR China bInstitute of Cardiovascular Disease, the First afflicated Hospital of Harbin Medical University, Harbin, 150081, PR China *Corresponding author: zhaojb168@sina.com fushiying12@sina.com

Background:

To access the prevalence of prehypertension and associated risk factors in residents of rural Lanxi county in Heilongjiang province. Methods: Through cluster sampling methods, a resident group of 5272 residents aged ¡Ý15 years old in Lanxi county was selected. A survey on blood pressure (BP) and associated risk factors was carried out. An overnight fasting blood specimen of residents aged ¡Ý35 years old was collected . Chi-square test, t-test and logistic regression analyses were then performed. Results: The total prevalence of prehypertension was 36.34%. The prevalence of prehypertension was higher in males (39.50%) than females (33.41%) (x2=58.989, PIntroduction The new blood pressure (BP) categories ¨C normal blood pressure, prehypertension and hypertension, were introduced by the Seventh Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC-7) in 2003[1]. ¡°Prehypertension¡± is defined as systolic blood pressure (SBP) 120 to 139 or diastolic blood pressure (DBP) 80 to 89 mm Hg, based on ¡°two or more properly measured seated BP readings on each of two or more office visits.¡± If SBP and DBP fall into different categories, the category associated with the higher of the two pressures is applied[2]. Prehypertension is a precursor of clinical hypertension and consequently of the cardiovascular disease and renal risks associated with elevated BP (ie, SBP ¡Ý140 or DBP ¡Ý90 mm Hg) [3]. The 2005 China Guidelines on Prevention and Management of High Blood Pressure defined this blood range of prehypertension as high normal blood pressure[4]. There are few studies on the prevelence of prehypertension in population. And there are only limited reports that investigated the prevalence of prehypertension in China. To our knowledge, this is the first report to study the prevalence and risk factors of prehypertension in population of Heilongjiang area.

Subjects and Methods Study subjects This investigation was based on a epidemiological study in Heilongjiang with a cross-sectional survey adopting a cluster random sampling scheme. According to a 1 / 3 ratio, we randomly selected 11 villages in Lanxi county of Heilongjiang province, in China. 5,272 residents including 2733 female subjects and 2539 male subjects were surveyed between 2006 and 2007, with response rate of 96.19%. All the subjects wre over 15 years old and had resided in the area for more than 5 years. Informed consent was obtained from each subject. An overnight-fasting venous blood specimen of residents aged ¡Ý35 years old were collected to measure fasting plasma glucose (FPG), triglyceride (TG) and high-density lipoprotein cholesterol (HDL-C) . Epidemiological Survey The survey was carried out using internationally standardized methods, following a common protocol. Data collection was conducted in examination centers at local stations or community clinics in the participants¡¯s residential area. In a few instances, where participants were unable to attend the examination centre, the interview and examination were conducted in their home. During the clinic or home visits, trained research staff administered a standard questionaire. Information including age, gender, nationality, education, family history of hypertension, medical history of hypertension and diabetes, was collected. Life habits such as smoking and drinking were also surveyed. The weight, height, waist circumference (WC) and BP of the subjects were measured. BMI was calculated as weight (kg)/height (m)2. We chose to use people's education levels (high school) as the indicator of socioeconomic status [5]. A smoker was defined in this inquiry as a person who had smoked as much as one cigarette a day for at least one year. Alcohol consumption was defined as the weekly consumption of beer, wine and hard liquor converted into grams of alcohol, which was more than 84 g/week [6]. The participant¡¯s Blood pressures were measured after at least 5 min of rest in a sitting position. And his/her right arm was placed at the heart level. Korotkoff phases I and V were used for SBP and DBP, respectively. SBP/DBP values were taken as the mean of 3 measurements recorded by well-trained doctors using a mercury sphygmomanometer. Measurements of TG, HDL-C and FPG Blood specimens were collected using a vacuum tube containing EDTA (Becton Dickinson, Franklin Lakes, NJ), and then centrifuged (2, 500g) and serum glucose was measured using glucose oxidase method (BECKMAN semi-automatic biochemistry analyzer, Model 700s, America) at the examination sites. The remained serum was sent to the Clinical testing centre of First Affiliated hospital of Harbin Medical University, and was analysed (Hitachi,Tokyo,Japan) on the same day. Definitions The criterias for normal BP, prehypertension and hypertension used in the present study were consistent with the definitions set by the JNC 7 report[1]. Normal BP was defined as not being on antihypertensive medication and having a SBP high school Family history (%) no yes smoking(%) nonsmoker ever smoker current smoker drinking(%) no yes WC* WC(%) Men 1698(94.70) 95(5.30) 35.229¡À14.889

516(28.78) 421(23.48) 378(21.08) 268(14.95) 140(7.81) 59(3.29) 11(0.61)

932(51.98) 850(47.41) 11(0.61)

1546(86.22) 247(13.78)

1244(69.38) 43(2.40) 506(28.22)

1578(88.01) 215(11.99) 75.242¡À8.713

1372(76.52) 421(23.48) 22.419¡À3.2023

1504(83.88) 262(14.61) 27(1.51) 1003(52.35)

1844(96.24) 72(3.76) 40.157¡À15.76

379(19.78) 356(18.58) 434(22.65) 368(19.21) 248(12.94) 103(5.38) 28(1.46)

1030(53.76) 869(45.35) 17(0.89)

1568(81.84) 348(18.16)

1189(62.06) 54(2.82) 673(35.13)

1524(79.54) 392(20.46) 78.472¡À9.0883

1314(68.58) 602(31.42) 23.42¡À3.5163

1403(73.23) 443(23.12) 70(3.65)

5.1124

91.4382

2.3143

13.2355

22.0903

48.5273

29.2300

65.0330

0.0238

0.3144

0.0003

Table 3 Comparison in FPG, TG and HDL-C between normotensives and prehypertensives aged ¡Ý 35 NT (n=856) PRE £¨n=1181£© ¦Ö2/t P TG(%) 590(68.93) 266(31.07)

806(94.16) 21(2.45) 29(3.39) 890(75.36£© 291(24.64)

880(74.51) 301(25.47)

1065(90.18) 46(3.90) 70(5.93) 5.5366

7.7145

10.5772 0.0186

0.0055

0.0050

Abbreviations: NT, normotensive; PRE, prehypertension; WC, waist circumference; TG, triglyceride; HDL-C, high-density lipoprotein cholesterol; FPG, fasting plasma glucose.

Rusults Associated With Blood Pressure Status From Univariate and Multivariate Logistic Regression Models Result from univariate logistic regression model showed that, being male, of Han ethnicity, age (¡Ý35£©, family history of hypertension, currently smoking, drinking status, WC (men ¡Ý85, women ¡Ý 80), BMI (¡Ý25.0 ), TG (¡Ý1.7) and FPG (¡Ý6.1) were risk factors of prehypertension. While HDL-C (high school Familyhistory(%) no yes smoking(%) nonsmoker ever smoker current smoker drinking(%) no yes WC(%) Men 1 0.698(0.510,0.955)

1 1.151(0.949,0.397) 1.563(1.291,1.893) 1.869(1.522,2.297) 2.412(1.886,3.084) 2.377(1.681,3.361) 3.463(1.703,7.042)

1 0.925(0.813,1.053) 1.398(0.652,3.001)

1 1.412(1.178,1.694)

1 1.314(0.873,1.977) 1.392(1.210,1.601)

1 1.888(0.576,2.261)

1 1.493(1.291,1.727) 0.0244

0.1539 0.2388 0.3894

0.0002

0.1901 1 0.733(0.530,1.014)

1 1.079(0.878,1.325) 1.459(1.173,1.817) 1.846(1.442,2.363) 2.449(1.841,3.259) 2.421(1.652,3.548) 3.998(1.924,8.310)

1 1.169(0.999,1.368) 1.192(0.540,2.632)

1 1.346(1.113,1.629)

1 0.770(0.499,1.188) 0.996(0.845,1.172)

1 1.152(0.925,1.434)

1 1.158(0.973,1.379) 0.0607

0.4702 0.0007 0.0509 0.6641

0.0022

0.2370 0.9578

0.2053

0.0991

BMI,kg/m2

TABLE 5: Rusults of TG, HDL-C and FPG from univariate and multivariate logistic regression models Univariate analysis Multivariate analysis OR(95%CI) P OR(95%CI) P TG,mol/L 1 0.759(0.624, 0.922)

1 1.658(0.981, 2.800) 1.826(1.173, 2.842)

0.0188 0.0055

0.0588 0.0076 1 1.218(0.982, 1.511)

1 0.794(0.652, 0.968)

1 1.559(0.921, 2.639) 1.691(1.083, 2.641)

0.0730

0.0221

0.0980 0.0209

TG, triglyceride; HDL-C, high-density lipoprotein cholesterol; FPG, fasting plasma glucose.

Discussion

Prehypertension is the primary stage of hypertension, it is important to study the prevalence and associated risk factors of prehypertension in a population for the prevention of hypertension. In Framingham Study [7] participants with BP levels in the 120 to 129/80 to 84 mmHg range, the BP progressed over 4 years to hypertensive levels in 17.6% of individuals between 30 and 64 years of age and in 25.5% of those ¡Ý65 years of age£¬In the group with BP levels in the 130 to 139/85 to 89 mm Hg range, the incidence of hypertension was 37.3% and 49.5% for the 30 to 64year and ¡Ý65-year groups, respectively. We can infer that prehypertensives at different ages progress to hypertensives at different rates. Our study found that the prevalence of prehypertension in Heilongjiang province was 36.34%. We can infer that there would some prehypertensives examined progressed to hypertensives over the next few years. The prevalences of prehypertension were high in 15~, 25~ and 35~, but the gender-specific prevalences of prehypertension decreased with age in subjects ¡Ý35. The prevalence of pehypertension in teenagers was high. We can infer that there would be part of prhypertension progressed to hypertension in young ages. These data portends the need for screening and prevention hypertensive programmes that begin at a young age. Univariate logistic model showed that, being male, of Han ethnicity, age ( ¡Ý35), with family history of hypertension, current smoking status, drinking status, WC (men ¡Ý85, women¡Ý80), BMI (¡Ý25), TG (¡Ý1.7 ) and diabetes were the risk factors of prehypertension, while HDL-C (References 1. Chobanian AV, Bakris GL, Black HR, Cushman WC, Green LA, Izzo JL Jr, Jones DW, Materson BJ, Oparil S, Wright JT Jr, Roccella EJ; National High Blood Pressure Education Program Coordinating Committee. Seventh report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure. Hypertension 2003;42:1206 ¨C1252. 2. JNC-6. The sixth report of the Joint National Committee on Prevention, Detection,Evaluation, and Treatment of High Blood Pressure. Arch Intern Med 1997;157:2413¨C2446. 3. Laura P. Svetkey. Management of Prehypertension. Hypertension 2005;45:1056-1061; 4. The Ministry of Health Cardiovascular Disease Prevention Research Center. Hypertension guildlines in China [J ]. Hypertension 2005;13:S14. 5. Wang Y, Wang QJ. The prevalence of prehypertension and hypertension among US adults according to the new Joint National Committee Guidelines. Arch Intern Med 2004;164:2126¨C34. 6. Pei-Shan Tsai, et al. Prevalence and determinants of prehypertension status in the Taiwanese general population. Journal of Hypertension 2005;23:1355-1360 7. Vasan RS, Larson MG, Leip EP, Kannel WB, Levy D. Assessment of frequency of progression to hypertension in non-hypertensive participants in the Framingham Heart Study: a cohort study. Lancet 2001;358:1682¨C1686. 8. Charles Agyemang, Ellis Owusu-Dabo. Prehypertension in the Ashanti region of Ghana, West Africa: An opportunity for early prevention of clinical hypertension. Public Health 2008;122:19¨C24 9. Zhaoqing Sun, et al. Prevalence and risk factors of the rural adult people prehypertension status in Liaoning Province of China. Circ J 2007;71:550 ¨C553 10. Wichai Aekplakorn, et al. Prevalence and management of prehypertension and hypertension by geographic regions of Thailand: the Third National Health Examination Survey, 2004. Journal of Hypertension 2008;26:191¨C198 11. Choi KM, Park HS, Han JH, Lee JS, Lee J, Ryu OH, Lee KW, Cho KH, Yoon D, Baik SH, Choi DS, Kim SM. Prevalence of prehypertension and hypertension in a Korean population: Korean National Health and Nutrition Survey 2001. J Hypertens 2006;24:1515¨C21 12. Sun Z, et al., Prevalence of prehypertension, hypertension and, associated risk factors in Mongolian and Han Chinese populationsin Northeast China. Int J Cardiol 2007 13. Greenlund KJ, Croft JB, Mensah GA. Prevalence of heart disease and stroke risk factors in persons with prehypertension in the United States, 1999¨C2000. Arch Intern Med 2004;164:2113¨C2118. 14. Okosun IS, Boltri JM, Anochie LK, Chandra KM. Racial/ethnic differences in prehypertension in American adults: population and relative attributable risks of abdominal obesity. J Hum Hypertens 2004;18:849¨C55. 15. Laura P. Svetkey. Management of Prehypertension. Hypertension 2005; 45:056-1061