Prevalence rate of metabolic syndrome and dyslipidemia in a large professional population in Beijing

Atherosclerosis 184 (2006) 188–192

Prevalence rate of metabolic syndrome and dyslipidemia in a large professional population in Beijing Zhi-Yan Li, Guo-Bing Xu ∗ , Tie-An Xia Department of Clinical Laboratory, Peking University First Hospital, Beijing 100034, China Received 3 June 2004; received in revised form 15 February 2005; accepted 2 March 2005 Available online 31 May 2005

Abstract The metabolic syndrome (MS) was a clustering of some cardiovascular risk factors, including hypertriglyceridemia, obesity, insulin resistance, glucose intolerance and hypertension. MS patients are at a risk of cardiovascular morbidity and mortality. Although the prevalence of MS in variety of ethnic group has been well documented, limited information is available about the prevalence in Chinese population. The aim of this study is to investigate the prevalence of the MS and dyslipidemia among 16,342 subjects (8801 males and 7541 females) aged 20–90 years in Beijing. 51.9% males and 40.8% females had at least one abnormal serum lipid concentration. The age-standardized prevalence of MS was 13.2% according to Chinese Diabetes Society (CDS) definition of the MS. The prevalence increased with age in both genders. MS was more commonly seen in males than in females (15.7% versus 10.2%). According to the diagnostic criterion, dyslipidemia was observed in 51.9% of males and 40.8% of females, and there was obvious difference between them (P < 0.001). This report on the MS and dyslipidemia from Beijing professional population showed a high prevalence of these disorders. Efforts on promoting healthy diets and physical activity in China should be undertaken. © 2005 Elsevier Ireland Ltd. All rights reserved. Keywords: Metabolic syndrome; Cholesterol; Low-density lipoprotein cholesterol; High-density lipoprotein cholesterol; Triglyceride; Prevalence

1. Introduction The metabolic syndrome (MS) was characteristic of elevations of apolipoprotein B, remnant lipoproteins and small LDL particles; reduced HDL cholesterol; elevated blood pressure; insulin resistance and glucose intolerance; and coagulation abnormalities. People with the MS were at increased risk for developing diabetes and cardiovascular disease as well as increased mortality from CVD and all causes. The Third Report of the National Cholesterol Education Program Expert Panel on detection, evaluation and treatment of high blood cholesterol in adults (ATP III) highlighted the importance of treating patients with MS to prevent coronary heart disease [1]. According to NHANES III, an estimated 47 million U.S. residents had the MS. The age-adjusted prevalence for adults ∗

Corresponding author. E-mail address: zyli [email protected] (G.-B. Xu).

0021-9150/$ – see front matter © 2005 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.atherosclerosis.2005.03.033

was 23.7%. The number of people with MS increased with age, affecting more than 40% of people in their 60s and 70s [2]. Limited information was available about the prevalence of the MS in China. Then the study was conducted to investigate the prevalence rate of MS and dyslipidemia in a population-based study in Beijing.

2. Material and methods 2.1. Study population From September 2003 to July 2004, a total of 16,344 adults in Beijing (8803 males, 7541 females) aged 20–90 years who attended the medical examinations were recruited in the study, including corporation clerks, educational faculties (over 90%) and health officers. The majority of the subjects had received good education (over 3/4 were university men and graduate students). 9.9% used antihypertensive

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medication, 3.4% received hypoglycemic agents or insulin and 5.7% used hypolipidemic medication. Informed consent was obtained from each subject. 2.2. General examination Subjects were asked to complete questionnaires regarding personal health, lifestyle and family health history. Replicate measures of height and waist circumference (WC) to the nearest 0.1 cm and weight to the nearest 0.1 kg were made. Then body mass index (BMI) was computed using weight (in kilograms) divided by the square of the height (in meters squared). Arterial blood pressure was measured at the end of the physical examination with subject in sitting position and at least 30 min at rest. Blood pressure measurements were taken by a cardiologist using standard mercury sphygmomanometer, three times, at the right arm relaxed and well supported by a table, with an angle of 45◦ from the trunk. The systolic blood pressure (SBP) level was determined by the first perception of sound (of tapping quality). The diastolic blood pressure (DBP) level was determined by phase V when the repetitive sounds become fully muffed (disappear). Changes in loudness were not considered. Means of replicate measurements were used in all analyses. 2.3. Biochemical analysis Subjects were asked to fast for 12 h before venipuncture. Serum samples were stored at 4 ◦ C, then analysis was carried out within 24 h. Blood glucose was determined using a glucose oxidase method. The concentrations of TC and TG were measured by routine enzymatic methods. HDL-C and LDLC concentration were measured by the homogeneous assay method. All lipids reagents as well as the lipid calibrator were made by Daiichi Pure Chemicals Co., Ltd. Assays for glucose and lipids were performed on a Hitachi 7600 clinical chemistry system (Hitachi, Tokyo, Japan). The biochemical assays were carried out in a clinical laboratory that followed the criteria of the World Health Organization Lipid Reference Laboratories. 2.4. Definitions and desirable cut-off points According to the ATP III criterion, subjects having three or more of the following abnormalities were defined as having the MS: (1) WC >102 cm in males or >88 cm in females; (2) blood pressure ≥130 mmHg systolic or ≥85 mmHg diastolic; (3) serum triglyceride level ≥1.7 mmol/L; (4) HDL-C <1.04 mmol/L in males or <1.29 mmol/L in females; (5) fasting blood glucose (FBG) level ≥6.1 mmol/L [1]. Subjects who did not meet the criterion of high blood pressure or high fasting glucose, but were treated with anti-hypertensive drugs or self-reported diabetes mellitus, were also considered to fulfil the criteria for high blood pressure or high fasting glucose, respectively.

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According to the Chinese Diabetes Society (CDS) definition, MS was defined as ≥3 of the following abnormalities: (1) BMI ≥25 kg/m2 ; (2) blood pressure ≥140/90 mmHg or under antihypertensive medication; (3) serum triglyceride level ≥1.7 mmol/L or HDL-C <0.91 mmol/L in males and <1.0 mmol/L in females; (4) FBG level ≥6.1 mmol/L or under antidiabetic medication [3]. Hypercholesterolemia was defined as TC levels >5.7 mmol/L, high LDL-C as LDL-C >3.4 mmol/L, hypertriglyceridemia as TG >1.7 mmol/L and low HDL-C as HDL-C <0.9 mmol/L [4]. 2.5. Statistical analysis For the purpose of data analysis, the study population was divided into 6 age groups (20–29, 30–39, 40–49, 50–59, 60–69 and ≥70 years). Variables have been compared using χ2 -test as appropriate. The P-values were two-sided, and the term statistically significantly implies a P-value <0.05. All data were analyzed using the Statistical Program for Social Sciences 10.0 software program (SPSS Inc., Chicago, IL).

3. Results 3.1. General features in the population Table 1 showed the clinical features of the subjects. 3.2. The age-standardized prevalence rate of MS using ATP III and CDS criteria The age-standardized prevalence of the MS using ATP III and CDS criteria in the study population was 8.6% and 12.2%, respectively. As shown in Fig. 1, the prevalence rate using CDS criteria was higher than that using ATP III criteria in both genders. The prevalence rate of MS defined by CDS criteria is shown in Table 2. The prevalence increased with age in both genders. In males, the lowest prevalence was seen in the 20–29 age group (5.8%), followed by 30–39 (8.5%), 40–49 (21.3%), 50–59 (23.1%), 60–69 (23.3%) and >70 (24.9%) age group. In females, 0.8% of 20–29 age group, 2.4% of 30–39 group, 12.6% of 40–49 group, 17.9% of 50–59 group, Table 1 The clinical data x¯ ± s

Item

Male (kg/m2 )

BMI WC (cm) SBP (mmHg) DBP (mmHg) TG (mmol/L) HDL-C (mmol/L) FBG (mmol/L)

24.1 87.2 118 76 1.74 1.27 4.90

Female ± ± ± ± ± ± ±

2.9 8.8 15 9 1.48 0.29 1.20

22.8 78.5 113 72 1.43 1.50 4.86

± ± ± ± ± ± ±

3.4 8.2 18 10 1.24 0.34 1.03

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Table 2 Prevalence of individual components of metabolic syndrome using ATP III and CDS criteria (%) Age group

Hypertension

Hyper TG

Hypo HDL-C

Hyper FBG

Overweight

MS

ATP III

CDS

ATP III/CDS

ATP III

CDS

ATP III/CDS

ATP III

CDS

ATP III

CDS

Male 20–29 30–39 40–49 50–59 60–69 ≥70

4.7 7.5 27.6 39.1 48.7 58.7

4.2 6.1 21.4 32.7 40.2 49.1

18.4 34.1 45.2 44.8 41.5 36.2

9.3 15.4 17.3 21.9 16.9 15.7

4.7 8.9 6.1 7.9 6.0 5.8

0.7 2.1 6.7 14.2 15.1 16.2

2.6 7.2 24.1 23.9 16.7 16.3

20.4 36.7 50.1 48.7 42.9 40.2

3.1 6.7 14.2 17.6 17.1 15.9

5.8 8.5 21.3 23.1 23.3 24.9

Female 20–29 30–39 40–49 50–59 60–69 ≥70

2.4 4.1 23.5 37.1 45.2 54.6

1.8 2.7 16.8 27.6 33.9 45.3

4.9 9.3 21.0 35.3 47.1 42.8

10.1 17.3 19.3 18.7 22.9 19.1

2.5 3.8 4.7 3.3 3.8 1.9

0.2 1.7 3.5 9.3 12.0 15.8

2.7 7.6 11.0 17.1 20.8 17.2

8.5 10.3 29.6 35.7 38.5 36.2

0.3 2.0 9.2 11.8 14.2 17.4

0.8 2.4 12.6 17.9 19.4 23.1

19.4% of 60–69 group and 23.1% of those over 70 had MS. Overall, the MS was more common in males than in females (14.2% versus 10.0%, P < 0.001). Table 2 displayed the prevalence of component of MS in relation to gender and age group. BMI ≥25 kg/m2 and hypertriglyceridaemia were the most common components of the MS, especially in males (38.8% and 32.95%, respectively). BMI ≥25 kg/m2 , hypertriglyceridaemia and low HDL-C were the most common combination of metabolic abnormalities (n = 901, 44.9%). Presence of one or more components of the MS was common in both genders: 35.0% had one component, 17.3% had two components, 10.1% had three components and 3.1% had four components (Table 3). 3.3. The prevalence rate of dyslipidemia According to the diagnostic criterion, dyslipidemia was observed in 51.9% of males and 40.8% of females, and there was obvious difference between them (P < 0.001). The current prevalence rates of high TC and high LDL-C is presented in Table 4. 4.1% of males and 2.6% of females aged 20–29 years had hypercholesteremia. In 40–49 age group, the rate was higher than 15% in both genders. Focusing our analysis in ≥70 age group, we observed that hypercholesteremia

Table 3 Age-standardized prevalence of components of metabolic syndrome using CDS criteria Number of components 0

1

2

3

4

Male Female

27.0 43.2

36.2 33.7

21.1 12.9

11.6 8.3

4.1 1.9

Total

34.5

35.0

17.3

10.1

3.1

occurred in 23.3% of males and 39.6% of females. The prevalence rate of hyper-LDL-C showed the same tendency as that of hyper-TC. Hypo-HDL-C occurred more frequently in males than in females. 6.4% of males and 1.6% of females had HDL-C levels <0.91 mmol/L. As shown in Table 3, 18.4% of males and only 4.9% of females aged 20–29 years had hypertriglyceridemia, and 45.2% of males and 21.0% of females in 40–49 age group. However, in the old group (60–69 and ≥70 age group), the prevalence rate was higher in females. There was a weak inverse correlation between TG concentrations and HDL-C level (r = −0.336, P = 0.01). Of those who had HDL-C levels <0.91 mmol/l, 11.7% of males and 2.4% of females had hypertriglyceridemia. Combined hyperlipidemia (TC >5.7 mmol/L and TG >1.7 mmol/L) was observed in 11.0% of males and 9.4% of females. The rate was dramatically lower than that of isolated high TG or isolated high TC.

4. Discussion

Fig. 1. The standardized prevalence of metabolic syndrome using ATP III and CDS criteria.

MS was originally described by Reaven [5] as a quartet of hypertension, glucose intolerance and dyslipidemia (high TG, low HDL-C), with insulin resistance or hyperinsulinemia. Epidemiologic studies have shown that MS occurs in a wide variety of ethnic groups including Caucasians, African–Americans, Mexican–Americans, Asian-Indians and Chinese [6–9]. The prevalence of the syndrome depends

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Table 4 Prevalence of dyslipidemia (%) Group

Hyper TC >5.7 mmol/L

Hyper LDL-C >3.6 mmol/L

Hyper TG >1.7 mmol/L

Hyper and hypo HDL-C <0.91 mmol/L

Combined hyperlipidemia TC >5.7 mmol/L and TG >1.7 mmol/L

Male 20–29 30–39 40–49 50–9 60–9 ≥70

4.1 8.8 17.9 18.4 18.9 23.3

5.0 9.1 17.5 18.5 19.0 20.7

18.4 34.1 45.2 44.8 41.5 36.2

4.7 8.9 6.1 7.9 6.0 5.8

2.3 5.4 14.0 12.2 10.4 12.3

Female 20–29 30–39 40–49 50–59 60–69 ≥70

2.6 3.1 16.4 32.3 39.4 39.6

1.9 3.6 11.3 22.7 30.1 30.7

4.9 9.3 21.0 35.3 47.1 42.8

1.7 1.6 1.5 1.4 1.5 0.7

0.7 0.9 5.4 16.2 22.6 20.7

on the definition used. The World Health Organization (WHO) [10], the European Group for the Study of Insulin Resistance (EGIR) [11] and the United States National Cholesterol Education Program (NCEP) Adult Treatment Panel (ATP) III [1] provided clinical definitions of MS. These criteria, although similar in that they focus on obesity, dyslipidemia, hyperglycemia and hypertension, differ in the individual constituents and the threshold levels. Owing to the lack of uniform criteria for the definition of MS, the prevalence of the MS has varied markedly between different studies [12]. In Shanghai, the frequency of the WHO syndrome was 17.14%, and was prevalent in 10.95% of population using the NCEP–ATP III [13]. In this study, the prevalence was 8.6%, which was lower than the rate using CDS criteria. The main reason was that the cut-off values of BMI and WC were unfit for Chinese population. In the study by Xing et al., the prevalence of WC > 102 cm in males and > 88cm in females was 7.54% [14]. While, in the white adults aged 20–74 years old in U.S., the rate was 37.8% [1]. Since the BMI and WC of Chinese were much smaller than those of the U.S. subjects, lower cut-off point should be used according to the suggestion of the Working Group of Obesity in China. A better definition has been put forward by CDS, which defined BMI ≥25 kg/m2 as overweight. The CDS criteria are more sensitive in predicting the risk of cardiovascular events than the NCEP-ATP criteria as well as the WHO criteria. In addition, the CDS criteria are more simple, practical and easier to popularize. In our study, according to the CDS criteria, 12.2% (age-standardized) of subjects had the MS. The prevalence rate was similar to that previously published [15]. The prevalence of the MS was shown higher among males compared with females in Beijing, which was in agreement with Chen [9]. However, among African–Americans and Mexican–Americans the MS was more frequent in females. The discrepancy in a variety of ethnic groups was likely due to the difference in body fat between males and females. In China, females generally have less consumption of fatty food,

and overweight and obesity are less common among them. In our study, the greatest difference observed between the two sexes was the prevalence of overweight (35.7% in males versus 23.1% in females). The prevalence of the syndrome increased with age in both genders. Others have also reported the effect of age on the prevalence of MS [9,15]. This increasing trend can be attributed to a similar age-related trend in each of the components of MS. Obesity and hypertriglyceridemia were the component of the MS most often observed, so we conducted ulterior study to investigate the current prevalence of dyslipidemia in an urban population of China. We observed that a large proportion of subjects had hyperlipidemia (51.9% of males and 40.8% of females). This could be attributed to the great change in dietary patterns and the decrease in strength of physical activity. There has been an increasing trend in fat consumption in China during the past decade [16,17] due to the rapid economic development and consequently, the abandonment of low-fat traditional diets in favor of high-fat ‘affluent’ diets [16]. On the other hand, more and more people in Beijing now go to work by car, bus or subway instead of on foot or by bike. They usually use washing machine and dishwasher as the substitute for handwork. Consequently, it was no wonder that serum lipid levels and the prevalence of dyslipidemia significantly increased in Beijing populations. It should be noted that our results might not be indicative of the Chinese population as a whole because we selected a professional population in Beijing as subjects instead of using random sampling. However, this population represented a large inhabitant group with average but stable income and living condition, less physical activities, better health awareness and higher educational background in big cities. In conclusion, the main findings in this study include an observed high prevalence rate of the MS and dyslipidemia in Beijing professional population, which may both increase the risk of CAD. Guidelines for the proper management of risk factors, targeting the prevention and treatment of atheroscle-

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rotic vascular disease, have been published in the U.S. [18] and Europe [19]. Such guidelines are also necessary for the countries in the Asian–Pacific area and it is necessary to collect data from this area on cardiovascular risk factors. Public health programs to alter the plasma lipid concentrations in Chinese population should be strengthened to prevent further increases in serum lipid levels as well as in CAD. And more efforts on promoting healthy diet, physical activity in China must be undertaken. References [1] Expert Panel on Detection and Treatment of High Blood Cholesterol in Adults. Executive summary of The Third Report of the National Cholesterol Education Program (NCEP) Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol (Adult Treatment Panel III). JAMA 2001; 285:2486–97. [2] Ford ES, Giles WH, Dietz WH. Prevalence of the metabolic syndrome among US adults: findings from the third National Health and Nutrition Examination Survey. JAMA 2002;287:356–9. [3] Expert Panel on Metabolic Syndrome of Chinese Diabetes Society. Recommendations on Metabolic Syndrome of Chinese Diabetes Society (Chinese). Chin J Diab 2004; 12:156–61. [4] Fang Y, Wang ZL, Ning TH, et al. Recommendations on prevention and treatment of dyslipidemia (Chinese). Chin J Cardiol 1997;25:169–75. [5] Reaven GM. Role of insulin resistance in human disease. Diabetes 1988;37:1595–607. [6] Ford, Earl S. The metabolic syndrome and mortality from cardiovascular disease and all-causes: findings from the National Health and Nutrition Examination Survey II Mortality Study. Atherosclerosis 2004;173:307–12. [7] M¨aki-Torkko N, Juonala M, R¨onnemaa T, Viikari J, Raitakari O. W09.234 Metabolic syndrome in Finnish young adults: prevalence and association to carotid artery intima-media thickness. The cardiovascular risk in young Finns study. Atherosclerosis 2004;5:54–5.

[8] Hell´enius M-L, Rosell M, Sandgren J, de Faire U. High prevalence of overweight and metabolic syndrome among 60 year old women and men in Stockholm, Sweden. Atherosclerosis 2000;151:276. [9] Chen L, Jia WP, Lu JX, et al. Prevalence of metabolic syndrome among Shanghai adults in China (Chinese). Chin J Cardiol 2003;31:909–12. [10] Alberti KG, Zimmet PZ. Definition, diagnosis and classification of diabetes mellitus and its complications. Part 1: diagnosis and classification of diabetes mellitus provisional report of a WHO consultation. Diab Med 1998;15:539–53. [11] Balkau B, Charles MA. Comment on the provisional report from the WHO consultation. European Group for the Study of Insulin Resistance (EGIR). Diab Med 1999;16:442–3. [12] Balkau B, Charles MA, Drivsholm T, et al. Frequency of the WHO metabolic syndrome in European cohorts, and an alternative definition of an insulin resistance syndrome. Diab Metab 2002;28:364–76. [13] Jia WP, Xiang KS, Chen L, et al. A comparison of the application of two working definitions of metabolic syndrome in Chinese population (Chinese). Natl Med J Chin 2004;84:534–8. [14] Xing HD, Chen W, Zhang XL, Fang JH. The survey of the situation of metabolic syndrome in the population of Dongcheng District of Beijing (Chinese). Chin J Diab 2004;112:169–72. [15] Li JZ, Wang S, Zeng P. Prevalence of metabolic syndrome in Beijing institutional populations (Chinese). Basic Med Sci Clin 2004;24:217–21. [16] The World Health Organization. Diet, nutrition, and the prevention of chronic diseases: Report of a WHO Study Group. WHO Technical Report Series 797: Geneva, 1990. [17] The World Bank. China: long-term issues and options in the health transition. The World Bank: Washington, DC, 1992. [18] National Cholesterol Education Program. Report of the NCEP Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults. Arch Int Med 1988; 148:36–69. [19] Py¨or¨al¨a K, De backer G, Graham I, Poole-Wilson P, Wood D. on behalf of the Task Force. Guidelines, Prevention of coronary heart disease in clinical practice; recommendations of the task force of the European Society of Cardiology, European Atherosclerosis Society, and European Society of Hypertension. Atherosclerosis 1994; 110:121–61.