- Email: [email protected]
Prevalence of prehypertension, hypertension and, associated risk factors in Mongolian and Han Chinese populations in Northeast China
International Journal of Cardiology 128 (2008) 250 – 254 www.elsevier.com/locate/ijcard
Prevalence of prehypertension, hypertension and, associated risk factors in Mongolian and Han Chinese populations in Northeast China☆ Zhaoqing Sun a , Liqiang Zheng b , Changlu Xu a , Jue Li b , Xingang Zhang a , Shuangshuang Liu a , Jiajin Li a , Dayi Hu b , Yingxian Sun a,⁎ a
Division of Cardiology, Shengjing Hospital of China Medical University, Shenyang, 110004, PR China b Heart, Lung and Blood Vessel Center, Tongji University, Shanghai, PR China Received 21 February 2007; received in revised form 15 August 2007; accepted 18 August 2007 Available online 21 December 2007
Abstract Background: The present study aimed to determine the prevalence of prehypertension, hypertension, and associated risk factors between Mongolian and Han populations in Northeast China. Methods: The study was conducted in 2004–2006, and used a multistage cluster sampling method to select a representative sample. A total of 9236 Mongolian people and 36,154 Han people in the same area, age 35 years or older, were examined. The survey on blood pressure and associated risk factors was carried out. Results: Overall, the prevalence of prehypertension for Mongolian people was 43.6%, for Han people was 44.3%. The prevalence of hypertension in Mongolian was higher than in Han (42% vs 36.7%, p b 0.05). The prevalence of hypertension was positively correlated with age, smoking, body mass index (BMI), waist circumference (WC), lipid disorder, diabetes, salt intake and family history of hypertension in Mongolian, whereas it was positively correlated with age, female, smoking, drinking, BMI, WC, lipid disorder, diabetes, salt intake and family history of hypertension in Han. The rates of awareness, treatment and control in Mongolian and Han were very low (29.7% vs 29.2%, 23.6% vs 23.5%, 0.7% vs 1.2%). Conclusions: Hypertension and prehypertension were common in Mongolian and Han populations in Northeast China, and it were associated with many risk factors. The percentages of hypertensives who were aware, treated, and controlled were unacceptably low. These results place great emphasis on the urgent need for a public health program to improve the detection, prevention and treatment of hypertension in the rural area of Northeast of China. © 2007 Elsevier Ireland Ltd. All rights reserved. Keywords: Prehypertension; Hypertension; Mongolian; Han
1. Introduction The Seventh Report of the Joint National Committee (JNC7) on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure proposed a new classification for individuals between normal blood pressure and established hypertension, in which people with systolic blood pressure ☆
That supported by Grants from the key technology Research and Development program of Liaoning Province (2003225003). ⁎ Corresponding author. Tel.: +86 13804068889; fax: +86 24 83955081. E-mail address: [email protected] (Y. Sun). 0167-5273/$ - see front matter © 2007 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.ijcard.2007.08.127
(SBP) between 120 and 139 mmHg or diastolic blood pressure (DBP) 80 and 89 mmHg were categorized as having ‘prehypertension’ [1]. Currently, prehypertension is not categorized as a disease; however, prehypertensive individuals are known to be at increased risk for progression to hypertension [2] and even slight elevation of blood pressure is considered to increase cardiovascular risk [3]. Thus, prehypertensive subjects should consider changing their lifestyles to prevent cardiovascular diseases [4]. The JNC-7 classification of prehypertension emphasizes the need for public education to decrease blood pressure levels in the at-risk population, and thus avert the development of hypertension in
Z. Sun et al. / International Journal of Cardiology 128 (2008) 250–254
many of these individuals. Hypertension is known to be one of the most important risk factors for cardiovascular disease and it is becoming more prevalent in developing countries. A recent cross-sectional study in China estimated that 129 million people aged 35–74 years have hypertension [5]. Although the exact causes and mechanisms of hypertension were not known, it was generally believed that both genetic factors and environmental factors [6], such as higher sodium intake [7], cigarette smoking [8] etc., were involved in determining the levels of blood pressure and the prevalence of hypertension. There are 56 nationalities in China. Han is the largest nationality. Mongolian is one of the minority nationalities. There are 5 million Mongolian people in China. Mongolian people like to make friends with others and like to eat meat and drink wine almost every day. Little was known about the genetic background and epidemiological data of prehypertension and hypertension in this population. Therefore, the present study was undertaken to compare the prevalence of prehypertension and hypertension, and the risk factors for hypertension between Mongolian and Han populations. 2. Materials and methods 2.1. Study subjects The procedures followed were in accordance with ethical standards of the responsible committee on human experimentation of China Medical University. Informed consent was obtained from each patient. This investigation was based on a large-scale epidemiological study in China with a crosssectional survey that adopted a multistage, stratified clustering sampling scheme [5] in rural areas of Fuxin County, Liaoning province, China. The participants with a history of tumor or congestive heart failure, or pregnant women were rejected. 53,400 subjects that were all had been over 35 years age should be surveyed, actually a total of 9236 Mongolian Chinese and 36,154 Han Chinese were surveyed between 2004 and 2006, and the response rate was 85%. Information on demographic characteristics including age, gender, education, ethnicity, occupation, and household income was collected. The information on history of hypertension and use of antihypertensive medications was also obtained by using a standard questionnaire. Life habits such as smoking and drinking were also surveyed. We chose to use people's education levels (bhigh school, high school, N high school) as the indicator of socioeconomic status [9], For most agerelated comparisons, participants were separated into four groups according to age (35–44 years, 45–54 years, 55– 64 years, ≥ 65 years). The weight, height and WC of subjects were measured; BMI was calculated as weight (kg)/height (m)2. According to the World Health Organization (WHO) criteria, BMI was categorized into three groups as normal (BMI b 25), overweight (25 ≤ BMI b 30) and obesity (BMI ≥ 30). Drinking status was assessed by alcohol consumption, alcohol consumption was defined as the weekly consumption of beer, wine and hard liquor converted
251
into grams of alcohol. Current drinking was defined as alcohol consumption (≥ 8 g/week) [10]. Smoking was defined as people who smoked at least one cigarette every day and continued for at least 1 year. Smoking was assessed as a part of the questionnaire. The individuals were asked whether they currently smoked or not (Do you smoke currently?). According to the specific diet habit of the rural area that we investigated, salt intake was measured through investigating the total amount of salt consuming in a family for 1 year to calculate salt intake for every person in the family in 1 day [11]. Diabetes and lipid disorders were defined as a history of physician-diagnosed report. 2.2. Blood pressure measurement Blood pressure was measured after the subject had rested for at least 5 min, using an electric sphygmomanometer (OMRON, HEM-741C) by doctors. The subject's arm was placed at the heart level. Three measurements were taken. SBP was defined as the average of three SBP readings. DBP was defined as the average of three DBP readings. As categorized by JNC-7 [1], we defined prehypertension as SBP between 120 and 139 mmHg or DBP between 80 and 89 mmHg. Hypertension was defined as an average SBP ≥ 140 mmHg, an average DBP ≥ 90 mmHg, and/or selfreport current treatment for hypertension with antihypertensive medication [5]. Awareness of hypertension was defined as self-report of any prior diagnosis of hypertension by a health care professional among the population defined as having hypertension. Treatment of hypertension was defined as use of a prescription medication for management of high blood pressure at the time of the interview. Control of hypertension was defined as pharmacological treatment of hypertension associated with an average SBP b 140 mmHg and an average DBP b90 mmHg [5]. 2.3. Statistical analysis All data analyses were conducted by use of SPSS 11.5 statistical software package. Continuous variables were presented as mean values and standard deviation. Categorical variables were presented as frequencies. Associations between categorical variables were tested by the use of contingency tables and the x2 test. Statistical hypotheses were tested using the 2-tailed t-test. To evaluate the association between hypertension and associated factors, multivariate logistic regression analysis was applied to estimate the odds ratio (OR) of hypertension through the levels of various explanatory factors. The adjusted OR was presented together with a 95% confidence interval (CI). For all comparisons, pvalues b 0.05 were considered statistically significant. 3. Results Table 1 presented the prevalence of prehypertension and hypertension between Mongolian people and Han people.
252
Z. Sun et al. / International Journal of Cardiology 128 (2008) 250–254
Table 1 Prevalence of prehypertension and hypertension between Mongolian and Han presented as percentage (%) of the total number of the studied subjects Age, year
35–44 45–54 55–64 ≥65 Total a
Han (n = 36,154)
Mongolian (n = 9236)
Prehypertension
Hypertension
Prehypertension
Hypertension
Male
Female
Total
Male
Female
Total
Male
Female
Total
Male
Female
Total
59.1 51.2 41.6 31.2 49
45.7 42.2 33.2 27.8 39.6
52.3 46.7 37.4 29.5 44.3
21.0 34.1 46.3 59.6 35.8
20.9 35.9 52.0 63.1 37.7
21.0 35.0 49.1 61.3 36.7
59.8 47.6 39.2 27.6 47.6
47.9 41.4 34.3 25.6 39.9
53.7 44.4 36.7 26.5 43.6
27.4 40.1 53.2 65.9 41.7
23.3 41.9 56.7 67.7 42.2
25.3 41.1 55 66.9 42 a
The prevalence of hypertension between Mongolian and Han is statistically significant (p b 0.05).
The prevalence of prehypertension was 43.6% in Mongolian (male 47.6%, female 39.9%) and 44.3% in Han (male 49%, female 39.6%). The prevalence of hypertension in Mongolian was higher than that in Han (42% vs 36.7%, p b 0.05). With the age increasing, the prevalence of prehypertension decreased, whereas the prevalence of hypertension increased in both nationalities. The prevalence of prehypertension in male was higher than that in female, whereas the prevalence of hypertension in male was lower than that in female. The demographic characteristics, health-related behaviors and lifestyle factors for Mongolian and Han are shown in Table 2. BMI, WC, current drinking status, lipid disorder, and salt intake were higher in Mongolian than that in Han (all p b 0.001). The mean systolic blood pressure and diastolic blood pressure were also higher in Mongolian than that in Han (p b 0.001). There were no statistical difference in age, current smoking status, diabetes between Mongolian and Han. The results of multivariate logistic regression analysis revealed that the prevalence of hypertension in Mongolian was positively correlated with age, smoking, BMI, WC, lipid disorder, diabetes, salt intake and family history of Table 2 Demographic characteristics of subjects between Mongolian and Han Characteristics
Male, % Age (years)* Education, % bHigh school High school NHigh school Mean systolic blood pressure (mmHg)* Mean diastolic blood pressure (mmHg)* BMI (kg/m2)* WC (cm)* Current smoking status, % Current drinking status, % Salt intake (g/day)* Diabetes Lipid disorder, %
Han
Mongolian
(N = 36,154)
(N = 9236)
p b0.001 0.697 b0.001
50 51.2 ± 11.8
48 51.2 ± 11.8
46.2 48.9 5.0 133.6 ± 22.6
42.5 48.8 8.7 136.1 ± 23.2
b0.001
82.5 ± 12.7
83.7 ± 12.8
b0.001
23.1 ± 3.1 80.4 ± 9.5 41.4 29.9 15.7 ± 12.3 0.4 3.8
23.6 ± 3.1 81.9 ± 9.0 41.4 34.1 16.3 ± 12.6 0.5 4.4
b0.001 b0.001 0.955 b0.001 b0.001 0.155 0.004
*Mean ± SD; WC = waist circumference; BMI = body mass index.
hypertension; whereas it was positively correlated with age, female, smoking, drinking, BMI, WC, lipid disorder, diabetes, salt intake and family history of hypertension in Han (Table 3). Table 4 presented the percentages of participants with hypertension who were aware of their hypertensive status, who was being treated with antihypertensive medications and who had their hypertension controlled. Overall, 29.7% Mongolian hypertensive people and 29.2% Han hypertensive people were aware of their diagnosis, only 23.6% for Mongolian and 23.5% for Han were taking prescribed medication to lower their blood pressure, and more Han people achieved blood pressure control than Mongolian people (1.2% vs 0.7%, p b 0.05). 4. Discussion Our study indicates that elevated blood pressure was a prevalent problem in Mongolian and Han populations of Northeast China; approximately 85.6% of Mongolian adults and 81% Han adults had prehypertension or hypertension. Compared to Han people, more Mongolian people had hypertension (42% vs 36.7%, p b 0.05). Low awareness and inadequate management of hypertension deserve great attention. Prehypertension is a new category of blood pressure classification. Our study found an overall prehypertension prevalence rate of 43.6% in Mongolian and 44.3% in Han. These were higher than the prevalence rate observed in other studies [9,10,12]. Consistent with previous reports, we found that the prevalence rate of prehypertension was greater in male than in female both in Mongolian adults and Han adults. We also revealed that the prevalence rate of prehypertension decreased with age increasing which was different from Taiwanese adults and American adults [9,10]. In our study, individuals aged ≥ 65 years were less likely to have prehypertension than 35–44 year s age group (26.5% vs 53.7%), the reason was that the majority of individuals in the old age group (66.9%) had progressed to clinical hypertension. Our study underscores the urgent need to inform the general public and health professionals about the new guidelines. The prehypertension people should be told the seriousness of hypertension and the importance of promoting
Z. Sun et al. / International Journal of Cardiology 128 (2008) 250–254
253
Table 3 Factors associated with hypertension between Mongolian and Han population from multivariate logistic regression models Han
Gender Male Female Age (per 1 year) Education status bHigh school High school NHigh school Smoking status No Yes Drinking status No Yes BMI, kg/m2 25–30 ≥30 WC, cm Lipid disorder No Yes Family history of hypertension No Yes Diabetes No Yes Salt intake (g/day)
Mongolian
OR (95% CI)
p
OR (95% CI)
p
1.000 (reference) 1.278 (1.204–1.357) 1.063 (1.060–1.065)
b0.001 b0.001
1.000 (reference) 1.042 (0.927–1.170) 1.064 (1.059–1.069)
0.491 b0.001
1.000 (reference) 0.846 (0.617–1.169) 0.731 (0.533–1.003)
0.300 0.052
1.000 (reference) 1.206 (0.760–1.913) 1.130 (0.715–1.786)
0.428 0.601
1.000 (reference) 1.126 (1.060–1.195)
b0.001
1.000 (reference) 1.146 (1.019–1.289)
1.000 (reference) 1.274 (1.192–1.361) 1.000 (reference) 1.879 (1.768–1.997) 2.903 (2.437–3.459) 1.018 (1.015–1.020)
b0.05
b0.001 b0.001 b0.001
1.000 (reference) 0.999 (0.882–1.103) 1.000 (reference) 1.698 (1.516–1.902) 2.403 (1.730–3.338) 1.018 (1.012–1.023)
b0.001 b0.001 b0.001
1.000 (reference) 3.158 (2.774–3.596)
b0.001
1.000 (reference) 2.606 (2.046–3.320)
b0.001
1.000 (reference) 2.930 (2.749–3.123)
b0.001
1.000 (reference) 2.748 (2.435–3.100)
b0.001
1.000 (reference) 2.295 (1.649–3.194) 1.006 (1.004–1.008)
b0.001 b0.001
1.000 (reference) 1.866 (1.042–3.342) 1.007 (1.003–1.011)
b0.05 b0.001
b0.001
0.994
Adjusted for gender, age, education, smoking status, drinking status, BMI, WC, salt intake, lipid disorder, diabetes and family history of hypertension. OR = odds ratio; CI = confidence interval; WC = waist circumference; BMI = body mass index.
appropriate lifestyle modification; so as to prevent these people from developing hypertension and cardiovascular disease. Hypertension was one of the most important cardiovascular risk factors. It has been considered that there may be difference in blood pressure levels, the prevalence of hypertension, and the risk factors for hypertension among the various races and regions. The current study showed that the prevalence of hypertension in Mongolian and Han was very high (Mongolian 42%, Han 36.7%); although the Table 4 Percentage of persons with hypertension who are aware, treated, and controlled, between Mongolian and Han Age, year
Han, %
Mongolian, %
Aware
Treated
Controlled
Aware
Treated
Controlled
35–44 45–54 55–64 ≥65 Total
19.9 26.6 35.1 33.5 29.2
14.9 20.9 29.0 27.3 23.5
1.1 1.3 1.4 1.1 1.2
18.3 27.8 36.1 35.5 29.7 a
12.9 21.4 30.3 29.0 23.6 a
0.4 1.2 0.6 0.6 0.7 b
a The awareness and treatment rate of hypertension between Mongolian and Han is not statistically significant (p N 0.05). b The controlled rate of hypertension in Mongolian is significantly different from that in Han (p b 0.05).
mean BMI, WC and the prevalence of lipid disorders and diabetes in the populations we investigated were not high as that observed in the West such as American and others; I think following economic development changes, in lifestyle and diet such as more drinking, smoking, high salt intake etc. and an increase in life expectancy may explain the high prevalence of hypertension. Different genetic factors may also play an important role in the development of hypertension. Similar to the findings of other studies [10,13–15], the present study indicates that age, smoking, overweight and obesity, lipid disorder, diabetes, salt intake and family history of hypertension were clearly associated with hypertension both in Mongolian and Han. Whereas female, drinking only were associated with hypertension occurring in Han. Previous studies have revealed that alcohol in larger amounts (more than two portions a day) and cigarette smoking increase blood pressure and overall mortality [16]. The mechanisms involved in the pressor effect of a moderate dose of alcohol primarily involve an increase in cardiac output and heart rate. Cigarette smoking raises blood pressure, probably through the nicotine-induced release of norepinephrine from adrenergic nerve endings. When smokers quit, a trivial rise in blood pressure may occur,
254
Z. Sun et al. / International Journal of Cardiology 128 (2008) 250–254
probably reflecting a gain in weight [17]. In the present study, the prevalence of hypertension was positively correlated with drinking only in Han, but not in Mongolian. The reason for this discrepancy was not clear. Overweight and obesity have become highly prevalent in Western countries and are rapidly reaching epidemic proportions in the developing world. The relationship between obesity and hypertension was well recognized. Overweight and obesity increase the risk of elevated blood pressure. Obesity can also cause metabolic syndrome, increased cardiac load and peripheral vascular resistance. A previous study reported that the prevalence of hypertension was 2- to 6-fold higher in obese than in normal-weight individuals [18]. In the present study, the individuals with increased BMI and WC were shown to be at increased risk for hypertension both in Mongolian and Han. Lipid disorder and diabetes were also positively correlated with the prevalence of hypertension. These findings suggest that the potential health benefits from obesity prevention are considerable public health importance. The current study showed that the prevalence of hypertension in Mongolian was higher than that in Han. The possible contributing factors might be as follow: 1) More Mongolian people were at the status of overweight or obesity. 2) More Mongolian people were at the status of lipid disorder; they consumed more salty food. 3) Genetic factors may play an important role in the development of hypertension. We will study for the reason. The rates of awareness, treatment and control in the present study were lower than that previously reported in our country (29.7% vs 44.7%, 23.6% vs 28.2%, 0.7% vs 8.1%) [5]. The reasons for the poor awareness, treatment and control of hypertension in Mongolian and Han were likely multifactor: such as poor health education, difficult access to medical care, furthermore, the lower income in rural areas is a barrier for treatment of hypertension. Increasing public awareness of hypertension using public education and health provider strategies may be a high national health priority. We also could conclude that most of who were treated were not controlled (Mongolian 0.7%, Han 1.2%); we should follow up treated subjects to find causes of failure to control hypertension. In conclusion, prehypertension and hypertension were found to be highly prevalent in Mongolian and Han, and the rates of awareness, treatment and control of hypertension were very low in both nationalities. These results underscore the urgent need for developing a high blood pressure education program to coordinate the effort of detection, prevention, and treatment of hypertension in the rural area of Northeast China. Acknowledgments We thank our subjects for their enthusiastic participation. This research was supported by Grants from the key technology
Research and Development program of Liaoning Province (2003225003).
References [1] Chobanian AV, Bakris GL, Black HR, Cushman WC, Green LA, Izzo Jr JL. The Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure: the JNC 7 report. JAMA 2003;289:2560–72. [2] 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;358:1682–6. [3] Lewington S, Clarke R, Qizilbash N, Peto R, Collins R. Age-specific relevance of usual blood pressure to vascular mortality: a meta-analysis of individual data for one million adults in 61 prospective studies. Lancet 2002;360:1903–13. [4] Whelton PK, He J, Appel LJ, et al. Primary prevention of hypertension: clinical and public health advisory from The National High Blood Pressure Education Program. JAMA 2002;288:1882–8. [5] Gu D, Reynolds K, Wu X. Prevalence, awareness, treatment, and control of hypertension in China. Hypertension 2002;40:920–7. [6] Sugimoto K, Katsuya T, Ohkubo T. Association between angiotensin II type 1 receptor gene polymorphism and essential hypertension: the Ohasama Study. Hypertens Res 2004;27:551–6. [7] Tochikubo O, Nishijima K. Sodium intake and cardiac sympatho-vagal balance in young men with high blood pressure. Hypertens Res 2004;27:393–8. [8] Matsui Y, Kario K, Ishikawa J, Hoshide S, Eguchi K, Shimada K. Smoking and antihypertensive medication: interaction between blood pressure reduction and arterial stiffness. Hypertens Res 2005;28: 631–8. [9] 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;164:2126–34. [10] Tsai P-S, Ke T-L, Huang C-J, Tsai J-C, Chen P-L, Wang S-Y. Prevalence and determinants of prehypertension status in the Taiwanese general population. J Hypertens 2005;23:1355–60. [11] Sun Z, Zheng L, Sun Y. Prevalence and Risk Factors of the Rural Adult People Prehypertension Status in Liaoning Province of China. Circ J 2007;71:550–3. [12] Choi KM, Park HS, Han JH, et al. Prevalence of prehypertension and hypertension in a Korean population: Korean National Health and Nutrition Survey 2001. J Hypertens 2006;24: 1515–21. [13] Gupta PC, Gupta R, Pednekar MS. Hypertension prevalence and blood pressure trends in 88 653 subjects in Mumbai, India. J Hum Hypertens 2004;18:907–10. [14] Geleijnse JM, Kok FJ, Grobbee DE. Impact of dietary and lifestyle factors on the prevalence of hypertension in Western populations. Eur J Public Health 2004;14:235–9. [15] Nakanishi N, Suzuki K. Daily life activity and the risk of developing hypertension in middle-aged Japanese men. Arch Intern Med 2005;165:214–20. [16] Matsui Y, Kario K, Ishikawa J, Hoshide S, Eguchi K, Shimada K. Smoking and antihypertensive medication: interaction between blood pressure reduction and arterial stiffness. Hypertens Res 2005;28: 631–8. [17] Terres W, Becker P, Rosenberg A. Changes in cardiovascular risk profile during the cessation of smoking. Am J Med 1994;97: 242–9. [18] Droyvold WB, Midthjell K, Nilsen TI, Holmen J. Change in body mass index and its impact on blood pressure: a prospective population study. Int J Obes Relat Metab Disord 2005;29:650–5.
Prevalence of prehypertension, hypertension and, associated risk factors in Mongolian and Han Chinese populations in Northeast China☆ Zhaoqing Sun a , Liqiang Zheng b , Changlu Xu a , Jue Li b , Xingang Zhang a , Shuangshuang Liu a , Jiajin Li a , Dayi Hu b , Yingxian Sun a,⁎ a
Division of Cardiology, Shengjing Hospital of China Medical University, Shenyang, 110004, PR China b Heart, Lung and Blood Vessel Center, Tongji University, Shanghai, PR China Received 21 February 2007; received in revised form 15 August 2007; accepted 18 August 2007 Available online 21 December 2007
Abstract Background: The present study aimed to determine the prevalence of prehypertension, hypertension, and associated risk factors between Mongolian and Han populations in Northeast China. Methods: The study was conducted in 2004–2006, and used a multistage cluster sampling method to select a representative sample. A total of 9236 Mongolian people and 36,154 Han people in the same area, age 35 years or older, were examined. The survey on blood pressure and associated risk factors was carried out. Results: Overall, the prevalence of prehypertension for Mongolian people was 43.6%, for Han people was 44.3%. The prevalence of hypertension in Mongolian was higher than in Han (42% vs 36.7%, p b 0.05). The prevalence of hypertension was positively correlated with age, smoking, body mass index (BMI), waist circumference (WC), lipid disorder, diabetes, salt intake and family history of hypertension in Mongolian, whereas it was positively correlated with age, female, smoking, drinking, BMI, WC, lipid disorder, diabetes, salt intake and family history of hypertension in Han. The rates of awareness, treatment and control in Mongolian and Han were very low (29.7% vs 29.2%, 23.6% vs 23.5%, 0.7% vs 1.2%). Conclusions: Hypertension and prehypertension were common in Mongolian and Han populations in Northeast China, and it were associated with many risk factors. The percentages of hypertensives who were aware, treated, and controlled were unacceptably low. These results place great emphasis on the urgent need for a public health program to improve the detection, prevention and treatment of hypertension in the rural area of Northeast of China. © 2007 Elsevier Ireland Ltd. All rights reserved. Keywords: Prehypertension; Hypertension; Mongolian; Han
1. Introduction The Seventh Report of the Joint National Committee (JNC7) on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure proposed a new classification for individuals between normal blood pressure and established hypertension, in which people with systolic blood pressure ☆
That supported by Grants from the key technology Research and Development program of Liaoning Province (2003225003). ⁎ Corresponding author. Tel.: +86 13804068889; fax: +86 24 83955081. E-mail address: [email protected] (Y. Sun). 0167-5273/$ - see front matter © 2007 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.ijcard.2007.08.127
(SBP) between 120 and 139 mmHg or diastolic blood pressure (DBP) 80 and 89 mmHg were categorized as having ‘prehypertension’ [1]. Currently, prehypertension is not categorized as a disease; however, prehypertensive individuals are known to be at increased risk for progression to hypertension [2] and even slight elevation of blood pressure is considered to increase cardiovascular risk [3]. Thus, prehypertensive subjects should consider changing their lifestyles to prevent cardiovascular diseases [4]. The JNC-7 classification of prehypertension emphasizes the need for public education to decrease blood pressure levels in the at-risk population, and thus avert the development of hypertension in
Z. Sun et al. / International Journal of Cardiology 128 (2008) 250–254
many of these individuals. Hypertension is known to be one of the most important risk factors for cardiovascular disease and it is becoming more prevalent in developing countries. A recent cross-sectional study in China estimated that 129 million people aged 35–74 years have hypertension [5]. Although the exact causes and mechanisms of hypertension were not known, it was generally believed that both genetic factors and environmental factors [6], such as higher sodium intake [7], cigarette smoking [8] etc., were involved in determining the levels of blood pressure and the prevalence of hypertension. There are 56 nationalities in China. Han is the largest nationality. Mongolian is one of the minority nationalities. There are 5 million Mongolian people in China. Mongolian people like to make friends with others and like to eat meat and drink wine almost every day. Little was known about the genetic background and epidemiological data of prehypertension and hypertension in this population. Therefore, the present study was undertaken to compare the prevalence of prehypertension and hypertension, and the risk factors for hypertension between Mongolian and Han populations. 2. Materials and methods 2.1. Study subjects The procedures followed were in accordance with ethical standards of the responsible committee on human experimentation of China Medical University. Informed consent was obtained from each patient. This investigation was based on a large-scale epidemiological study in China with a crosssectional survey that adopted a multistage, stratified clustering sampling scheme [5] in rural areas of Fuxin County, Liaoning province, China. The participants with a history of tumor or congestive heart failure, or pregnant women were rejected. 53,400 subjects that were all had been over 35 years age should be surveyed, actually a total of 9236 Mongolian Chinese and 36,154 Han Chinese were surveyed between 2004 and 2006, and the response rate was 85%. Information on demographic characteristics including age, gender, education, ethnicity, occupation, and household income was collected. The information on history of hypertension and use of antihypertensive medications was also obtained by using a standard questionnaire. Life habits such as smoking and drinking were also surveyed. We chose to use people's education levels (bhigh school, high school, N high school) as the indicator of socioeconomic status [9], For most agerelated comparisons, participants were separated into four groups according to age (35–44 years, 45–54 years, 55– 64 years, ≥ 65 years). The weight, height and WC of subjects were measured; BMI was calculated as weight (kg)/height (m)2. According to the World Health Organization (WHO) criteria, BMI was categorized into three groups as normal (BMI b 25), overweight (25 ≤ BMI b 30) and obesity (BMI ≥ 30). Drinking status was assessed by alcohol consumption, alcohol consumption was defined as the weekly consumption of beer, wine and hard liquor converted
251
into grams of alcohol. Current drinking was defined as alcohol consumption (≥ 8 g/week) [10]. Smoking was defined as people who smoked at least one cigarette every day and continued for at least 1 year. Smoking was assessed as a part of the questionnaire. The individuals were asked whether they currently smoked or not (Do you smoke currently?). According to the specific diet habit of the rural area that we investigated, salt intake was measured through investigating the total amount of salt consuming in a family for 1 year to calculate salt intake for every person in the family in 1 day [11]. Diabetes and lipid disorders were defined as a history of physician-diagnosed report. 2.2. Blood pressure measurement Blood pressure was measured after the subject had rested for at least 5 min, using an electric sphygmomanometer (OMRON, HEM-741C) by doctors. The subject's arm was placed at the heart level. Three measurements were taken. SBP was defined as the average of three SBP readings. DBP was defined as the average of three DBP readings. As categorized by JNC-7 [1], we defined prehypertension as SBP between 120 and 139 mmHg or DBP between 80 and 89 mmHg. Hypertension was defined as an average SBP ≥ 140 mmHg, an average DBP ≥ 90 mmHg, and/or selfreport current treatment for hypertension with antihypertensive medication [5]. Awareness of hypertension was defined as self-report of any prior diagnosis of hypertension by a health care professional among the population defined as having hypertension. Treatment of hypertension was defined as use of a prescription medication for management of high blood pressure at the time of the interview. Control of hypertension was defined as pharmacological treatment of hypertension associated with an average SBP b 140 mmHg and an average DBP b90 mmHg [5]. 2.3. Statistical analysis All data analyses were conducted by use of SPSS 11.5 statistical software package. Continuous variables were presented as mean values and standard deviation. Categorical variables were presented as frequencies. Associations between categorical variables were tested by the use of contingency tables and the x2 test. Statistical hypotheses were tested using the 2-tailed t-test. To evaluate the association between hypertension and associated factors, multivariate logistic regression analysis was applied to estimate the odds ratio (OR) of hypertension through the levels of various explanatory factors. The adjusted OR was presented together with a 95% confidence interval (CI). For all comparisons, pvalues b 0.05 were considered statistically significant. 3. Results Table 1 presented the prevalence of prehypertension and hypertension between Mongolian people and Han people.
252
Z. Sun et al. / International Journal of Cardiology 128 (2008) 250–254
Table 1 Prevalence of prehypertension and hypertension between Mongolian and Han presented as percentage (%) of the total number of the studied subjects Age, year
35–44 45–54 55–64 ≥65 Total a
Han (n = 36,154)
Mongolian (n = 9236)
Prehypertension
Hypertension
Prehypertension
Hypertension
Male
Female
Total
Male
Female
Total
Male
Female
Total
Male
Female
Total
59.1 51.2 41.6 31.2 49
45.7 42.2 33.2 27.8 39.6
52.3 46.7 37.4 29.5 44.3
21.0 34.1 46.3 59.6 35.8
20.9 35.9 52.0 63.1 37.7
21.0 35.0 49.1 61.3 36.7
59.8 47.6 39.2 27.6 47.6
47.9 41.4 34.3 25.6 39.9
53.7 44.4 36.7 26.5 43.6
27.4 40.1 53.2 65.9 41.7
23.3 41.9 56.7 67.7 42.2
25.3 41.1 55 66.9 42 a
The prevalence of hypertension between Mongolian and Han is statistically significant (p b 0.05).
The prevalence of prehypertension was 43.6% in Mongolian (male 47.6%, female 39.9%) and 44.3% in Han (male 49%, female 39.6%). The prevalence of hypertension in Mongolian was higher than that in Han (42% vs 36.7%, p b 0.05). With the age increasing, the prevalence of prehypertension decreased, whereas the prevalence of hypertension increased in both nationalities. The prevalence of prehypertension in male was higher than that in female, whereas the prevalence of hypertension in male was lower than that in female. The demographic characteristics, health-related behaviors and lifestyle factors for Mongolian and Han are shown in Table 2. BMI, WC, current drinking status, lipid disorder, and salt intake were higher in Mongolian than that in Han (all p b 0.001). The mean systolic blood pressure and diastolic blood pressure were also higher in Mongolian than that in Han (p b 0.001). There were no statistical difference in age, current smoking status, diabetes between Mongolian and Han. The results of multivariate logistic regression analysis revealed that the prevalence of hypertension in Mongolian was positively correlated with age, smoking, BMI, WC, lipid disorder, diabetes, salt intake and family history of Table 2 Demographic characteristics of subjects between Mongolian and Han Characteristics
Male, % Age (years)* Education, % bHigh school High school NHigh school Mean systolic blood pressure (mmHg)* Mean diastolic blood pressure (mmHg)* BMI (kg/m2)* WC (cm)* Current smoking status, % Current drinking status, % Salt intake (g/day)* Diabetes Lipid disorder, %
Han
Mongolian
(N = 36,154)
(N = 9236)
p b0.001 0.697 b0.001
50 51.2 ± 11.8
48 51.2 ± 11.8
46.2 48.9 5.0 133.6 ± 22.6
42.5 48.8 8.7 136.1 ± 23.2
b0.001
82.5 ± 12.7
83.7 ± 12.8
b0.001
23.1 ± 3.1 80.4 ± 9.5 41.4 29.9 15.7 ± 12.3 0.4 3.8
23.6 ± 3.1 81.9 ± 9.0 41.4 34.1 16.3 ± 12.6 0.5 4.4
b0.001 b0.001 0.955 b0.001 b0.001 0.155 0.004
*Mean ± SD; WC = waist circumference; BMI = body mass index.
hypertension; whereas it was positively correlated with age, female, smoking, drinking, BMI, WC, lipid disorder, diabetes, salt intake and family history of hypertension in Han (Table 3). Table 4 presented the percentages of participants with hypertension who were aware of their hypertensive status, who was being treated with antihypertensive medications and who had their hypertension controlled. Overall, 29.7% Mongolian hypertensive people and 29.2% Han hypertensive people were aware of their diagnosis, only 23.6% for Mongolian and 23.5% for Han were taking prescribed medication to lower their blood pressure, and more Han people achieved blood pressure control than Mongolian people (1.2% vs 0.7%, p b 0.05). 4. Discussion Our study indicates that elevated blood pressure was a prevalent problem in Mongolian and Han populations of Northeast China; approximately 85.6% of Mongolian adults and 81% Han adults had prehypertension or hypertension. Compared to Han people, more Mongolian people had hypertension (42% vs 36.7%, p b 0.05). Low awareness and inadequate management of hypertension deserve great attention. Prehypertension is a new category of blood pressure classification. Our study found an overall prehypertension prevalence rate of 43.6% in Mongolian and 44.3% in Han. These were higher than the prevalence rate observed in other studies [9,10,12]. Consistent with previous reports, we found that the prevalence rate of prehypertension was greater in male than in female both in Mongolian adults and Han adults. We also revealed that the prevalence rate of prehypertension decreased with age increasing which was different from Taiwanese adults and American adults [9,10]. In our study, individuals aged ≥ 65 years were less likely to have prehypertension than 35–44 year s age group (26.5% vs 53.7%), the reason was that the majority of individuals in the old age group (66.9%) had progressed to clinical hypertension. Our study underscores the urgent need to inform the general public and health professionals about the new guidelines. The prehypertension people should be told the seriousness of hypertension and the importance of promoting
Z. Sun et al. / International Journal of Cardiology 128 (2008) 250–254
253
Table 3 Factors associated with hypertension between Mongolian and Han population from multivariate logistic regression models Han
Gender Male Female Age (per 1 year) Education status bHigh school High school NHigh school Smoking status No Yes Drinking status No Yes BMI, kg/m2 25–30 ≥30 WC, cm Lipid disorder No Yes Family history of hypertension No Yes Diabetes No Yes Salt intake (g/day)
Mongolian
OR (95% CI)
p
OR (95% CI)
p
1.000 (reference) 1.278 (1.204–1.357) 1.063 (1.060–1.065)
b0.001 b0.001
1.000 (reference) 1.042 (0.927–1.170) 1.064 (1.059–1.069)
0.491 b0.001
1.000 (reference) 0.846 (0.617–1.169) 0.731 (0.533–1.003)
0.300 0.052
1.000 (reference) 1.206 (0.760–1.913) 1.130 (0.715–1.786)
0.428 0.601
1.000 (reference) 1.126 (1.060–1.195)
b0.001
1.000 (reference) 1.146 (1.019–1.289)
1.000 (reference) 1.274 (1.192–1.361) 1.000 (reference) 1.879 (1.768–1.997) 2.903 (2.437–3.459) 1.018 (1.015–1.020)
b0.05
b0.001 b0.001 b0.001
1.000 (reference) 0.999 (0.882–1.103) 1.000 (reference) 1.698 (1.516–1.902) 2.403 (1.730–3.338) 1.018 (1.012–1.023)
b0.001 b0.001 b0.001
1.000 (reference) 3.158 (2.774–3.596)
b0.001
1.000 (reference) 2.606 (2.046–3.320)
b0.001
1.000 (reference) 2.930 (2.749–3.123)
b0.001
1.000 (reference) 2.748 (2.435–3.100)
b0.001
1.000 (reference) 2.295 (1.649–3.194) 1.006 (1.004–1.008)
b0.001 b0.001
1.000 (reference) 1.866 (1.042–3.342) 1.007 (1.003–1.011)
b0.05 b0.001
b0.001
0.994
Adjusted for gender, age, education, smoking status, drinking status, BMI, WC, salt intake, lipid disorder, diabetes and family history of hypertension. OR = odds ratio; CI = confidence interval; WC = waist circumference; BMI = body mass index.
appropriate lifestyle modification; so as to prevent these people from developing hypertension and cardiovascular disease. Hypertension was one of the most important cardiovascular risk factors. It has been considered that there may be difference in blood pressure levels, the prevalence of hypertension, and the risk factors for hypertension among the various races and regions. The current study showed that the prevalence of hypertension in Mongolian and Han was very high (Mongolian 42%, Han 36.7%); although the Table 4 Percentage of persons with hypertension who are aware, treated, and controlled, between Mongolian and Han Age, year
Han, %
Mongolian, %
Aware
Treated
Controlled
Aware
Treated
Controlled
35–44 45–54 55–64 ≥65 Total
19.9 26.6 35.1 33.5 29.2
14.9 20.9 29.0 27.3 23.5
1.1 1.3 1.4 1.1 1.2
18.3 27.8 36.1 35.5 29.7 a
12.9 21.4 30.3 29.0 23.6 a
0.4 1.2 0.6 0.6 0.7 b
a The awareness and treatment rate of hypertension between Mongolian and Han is not statistically significant (p N 0.05). b The controlled rate of hypertension in Mongolian is significantly different from that in Han (p b 0.05).
mean BMI, WC and the prevalence of lipid disorders and diabetes in the populations we investigated were not high as that observed in the West such as American and others; I think following economic development changes, in lifestyle and diet such as more drinking, smoking, high salt intake etc. and an increase in life expectancy may explain the high prevalence of hypertension. Different genetic factors may also play an important role in the development of hypertension. Similar to the findings of other studies [10,13–15], the present study indicates that age, smoking, overweight and obesity, lipid disorder, diabetes, salt intake and family history of hypertension were clearly associated with hypertension both in Mongolian and Han. Whereas female, drinking only were associated with hypertension occurring in Han. Previous studies have revealed that alcohol in larger amounts (more than two portions a day) and cigarette smoking increase blood pressure and overall mortality [16]. The mechanisms involved in the pressor effect of a moderate dose of alcohol primarily involve an increase in cardiac output and heart rate. Cigarette smoking raises blood pressure, probably through the nicotine-induced release of norepinephrine from adrenergic nerve endings. When smokers quit, a trivial rise in blood pressure may occur,
254
Z. Sun et al. / International Journal of Cardiology 128 (2008) 250–254
probably reflecting a gain in weight [17]. In the present study, the prevalence of hypertension was positively correlated with drinking only in Han, but not in Mongolian. The reason for this discrepancy was not clear. Overweight and obesity have become highly prevalent in Western countries and are rapidly reaching epidemic proportions in the developing world. The relationship between obesity and hypertension was well recognized. Overweight and obesity increase the risk of elevated blood pressure. Obesity can also cause metabolic syndrome, increased cardiac load and peripheral vascular resistance. A previous study reported that the prevalence of hypertension was 2- to 6-fold higher in obese than in normal-weight individuals [18]. In the present study, the individuals with increased BMI and WC were shown to be at increased risk for hypertension both in Mongolian and Han. Lipid disorder and diabetes were also positively correlated with the prevalence of hypertension. These findings suggest that the potential health benefits from obesity prevention are considerable public health importance. The current study showed that the prevalence of hypertension in Mongolian was higher than that in Han. The possible contributing factors might be as follow: 1) More Mongolian people were at the status of overweight or obesity. 2) More Mongolian people were at the status of lipid disorder; they consumed more salty food. 3) Genetic factors may play an important role in the development of hypertension. We will study for the reason. The rates of awareness, treatment and control in the present study were lower than that previously reported in our country (29.7% vs 44.7%, 23.6% vs 28.2%, 0.7% vs 8.1%) [5]. The reasons for the poor awareness, treatment and control of hypertension in Mongolian and Han were likely multifactor: such as poor health education, difficult access to medical care, furthermore, the lower income in rural areas is a barrier for treatment of hypertension. Increasing public awareness of hypertension using public education and health provider strategies may be a high national health priority. We also could conclude that most of who were treated were not controlled (Mongolian 0.7%, Han 1.2%); we should follow up treated subjects to find causes of failure to control hypertension. In conclusion, prehypertension and hypertension were found to be highly prevalent in Mongolian and Han, and the rates of awareness, treatment and control of hypertension were very low in both nationalities. These results underscore the urgent need for developing a high blood pressure education program to coordinate the effort of detection, prevention, and treatment of hypertension in the rural area of Northeast China. Acknowledgments We thank our subjects for their enthusiastic participation. This research was supported by Grants from the key technology
Research and Development program of Liaoning Province (2003225003).
References [1] Chobanian AV, Bakris GL, Black HR, Cushman WC, Green LA, Izzo Jr JL. The Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure: the JNC 7 report. JAMA 2003;289:2560–72. [2] 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;358:1682–6. [3] Lewington S, Clarke R, Qizilbash N, Peto R, Collins R. Age-specific relevance of usual blood pressure to vascular mortality: a meta-analysis of individual data for one million adults in 61 prospective studies. Lancet 2002;360:1903–13. [4] Whelton PK, He J, Appel LJ, et al. Primary prevention of hypertension: clinical and public health advisory from The National High Blood Pressure Education Program. JAMA 2002;288:1882–8. [5] Gu D, Reynolds K, Wu X. Prevalence, awareness, treatment, and control of hypertension in China. Hypertension 2002;40:920–7. [6] Sugimoto K, Katsuya T, Ohkubo T. Association between angiotensin II type 1 receptor gene polymorphism and essential hypertension: the Ohasama Study. Hypertens Res 2004;27:551–6. [7] Tochikubo O, Nishijima K. Sodium intake and cardiac sympatho-vagal balance in young men with high blood pressure. Hypertens Res 2004;27:393–8. [8] Matsui Y, Kario K, Ishikawa J, Hoshide S, Eguchi K, Shimada K. Smoking and antihypertensive medication: interaction between blood pressure reduction and arterial stiffness. Hypertens Res 2005;28: 631–8. [9] 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;164:2126–34. [10] Tsai P-S, Ke T-L, Huang C-J, Tsai J-C, Chen P-L, Wang S-Y. Prevalence and determinants of prehypertension status in the Taiwanese general population. J Hypertens 2005;23:1355–60. [11] Sun Z, Zheng L, Sun Y. Prevalence and Risk Factors of the Rural Adult People Prehypertension Status in Liaoning Province of China. Circ J 2007;71:550–3. [12] Choi KM, Park HS, Han JH, et al. Prevalence of prehypertension and hypertension in a Korean population: Korean National Health and Nutrition Survey 2001. J Hypertens 2006;24: 1515–21. [13] Gupta PC, Gupta R, Pednekar MS. Hypertension prevalence and blood pressure trends in 88 653 subjects in Mumbai, India. J Hum Hypertens 2004;18:907–10. [14] Geleijnse JM, Kok FJ, Grobbee DE. Impact of dietary and lifestyle factors on the prevalence of hypertension in Western populations. Eur J Public Health 2004;14:235–9. [15] Nakanishi N, Suzuki K. Daily life activity and the risk of developing hypertension in middle-aged Japanese men. Arch Intern Med 2005;165:214–20. [16] Matsui Y, Kario K, Ishikawa J, Hoshide S, Eguchi K, Shimada K. Smoking and antihypertensive medication: interaction between blood pressure reduction and arterial stiffness. Hypertens Res 2005;28: 631–8. [17] Terres W, Becker P, Rosenberg A. Changes in cardiovascular risk profile during the cessation of smoking. Am J Med 1994;97: 242–9. [18] Droyvold WB, Midthjell K, Nilsen TI, Holmen J. Change in body mass index and its impact on blood pressure: a prospective population study. Int J Obes Relat Metab Disord 2005;29:650–5.