IJCA-18123; No of Pages 2 International Journal of Cardiology xxx (2014) xxx–xxx
Contents lists available at ScienceDirect
International Journal of Cardiology journal homepage: www.elsevier.com/locate/ijcard
Letter to the Editor
Socioeconomic inequalities in abdominal obesity among children and adolescents in Shandong, China Ying-xiu Zhang ⁎, Jin-shan Zhao, Zun-hua Chu Shandong Center for Disease Control and Prevention, Shandong University Institute of Preventive Medicine, Shandong, China
a r t i c l e
i n f o
Article history: Received 14 April 2014 Accepted 17 April 2014 Available online xxxx Keywords: Abdominal obesity Prevalence Regional disparity Socioeconomic status Child and adolescent
The prevalence of childhood obesity is increasing rapidly worldwide [1]. Socioeconomic factors may play an important role in the development of obesity. Many previous studies have confirmed that the population distribution of childhood obesity is associated with socioeconomic status (SES) and that the patterns vary from country to country, depending on the degree of economic development of a country [2,3]. Studies from developed countries showed that high SES youths are less likely to be obese compared with their lower SES counterparts [4,5]. In contrast, in developing countries such as Indonesia, Brazil and China, high SES youths are more likely to be obese compared with their lower SES counterparts [6–8]. Abdominal fat distribution is associated with greater health risks than total body fat [9]. Recent evidence suggests that compared with overall obesity, abdominal obesity appears to be more strongly associated with cardiovascular disease (CVD) risk factors [10]. In this article, based on provincial data in 2010, we report the prevalence and regional disparities in abdominal obesity among children and adolescents in Shandong, China. Data for this study were obtained from a large cross-sectional survey of schoolchildren. A total of 42,234 students (21,192 boys and 21,042 girls) from 16 districts in Shandong Province, students of Han nationality, aged 7–18 years, participated in the National Surveys on Chinese Students' Constitution and Health, which were carried out in September ⁎ Corresponding author at: Shandong Center for Disease Control and Prevention, Shandong University Institute of Preventive Medicine, 16992 Jingshi Road, Jinan 250014, Shandong, China. Tel./fax: +86 531 82679413. E-mail address: [email protected] (Y. Zhang).
to October 2010. It is, so far, the largest representative sample of schoolaged children and adolescents in Shandong, China. All subjects voluntarily joined this study with informed consents. The sampling method was stratified multistage sampling based on selected primary and secondary schools and has been described in detail elsewhere [11]. The information about gross domestic product (GDP) per capita of the 16 districts in 2010 was collected from Shandong Statistical Yearbook [12]. The 16 districts were divided into three groups (high SES, moderate SES and low SES) according to their GDP per capita in 2010. High SES was defined as GDP per capita above 8000 dollars (including Jinan, Qingdao, Yantai, Weihai, Dongying and Zibo), moderate SES was defined as GDP per capita above 5000 but below 8000 dollars (including Weifang, Taian, Laiwu, Binzhou and Rizhao), and low SES was defined as GDP per capita below 5000 dollars (including Jining, Dezhou, Liaocheng, Linyi and Heze). All measurements were conducted by a team of trained technicians in each of the 16 districts. Each technician is required to pass a training course for anthropometric measurement organized by the investigation team in Shandong. Waist circumference (WC) was measured midway between the lowest rib and the superior border of the iliac crest with an inelastic measuring tape at the end of normal expiration to the nearest 0.1 cm. Abdominal obesity was defined by previously published WC references (≥ 90th percentile) based on Chinese national data [13]. The mean values of WC for boys and girls aged 7–18 years in different SES districts are shown in Figs. 1 and 2. We found that boys and girls in high SES districts had higher WC levels compared with their peers in moderate and low SES districts. The mean values of WC of children and adolescents aged 7 to 18 years in high SES districts were higher than in moderate and low SES districts by 1.08–2.11 cm and 1.86–3.15 cm for boys and 0.60–1.27 cm and 1.20–2.24 cm for girls. The overall prevalence of abdominal obesity among children and adolescents aged 7–18 years was 20.21% and 16.59% for boys and girls, respectively; χ2 tests indicated that boys had higher prevalence compared with girls (χ2 = 92.12, P b 0.01). The prevalence of abdominal obesity among children and adolescents by regional SES is shown in Table 1. An increasing trend was observed from the low SES group to the moderate and high SES groups. The overall prevalence rates of abdominal obesity in the three SES groups were 16.12%, 20.51% and 22.84% for boys and 15.47%, 16.66% and 17.34% for girls. For boys, statistical significant differences were observed between any two groups (P b 0.01). For girls, statistical significant differences were observed between the high and low SES groups (P b 0.01).
http://dx.doi.org/10.1016/j.ijcard.2014.04.222 0167-5273/© 2014 Elsevier Ireland Ltd. All rights reserved.
Please cite this article as: Zhang Y, et al, Socioeconomic inequalities in abdominal obesity among children and adolescents in Shandong, China, Int J Cardiol (2014), http://dx.doi.org/10.1016/j.ijcard.2014.04.222
2
Y. Zhang et al. / International Journal of Cardiology xxx (2014) xxx–xxx
80
Table 1 Prevalence of abdominal obesity among children and adolescents aged 7–18 years in different SES districts.
75
Groups
cm
70 High SES Moderate SES Low SES
65 High SES
60
Low SES
% (95% CI)
n
% (95% CI)
9050 5896 6246
22.84 (21.98–23.70) 20.51 (19.48–21.54) 16.12 (15.21–17.03) χ2 = 103.85, P = 0.000
8918 5853 6271
17.34 (16.55–18.13) 16.66 (15.71–17.61) 15.47 (14.57–16.37) χ2 = 9.31, P = 0.009
SES: socioeconomic status.
Age/years
7
8
9
10
11
12
13
14
15
16
17
18
Fig. 1. Mean values of WC for boys aged 7–18 years in different SES districts.
80 75 70
cm
Girls
n
Moderate SES
55 50
Boys
65
References
High SES
60
Moderate SES Low SES
55
Age/years
50 7
8
9
10
11
12
13
14
15
16
The present study further highlights that the prevalence of childhood abdominal obesity is wide in Shandong Province, one of the populous provinces in China. Abdominal obesity among children and adolescents is associated with affluence. Intervention and strategy for obesity should be based on this specific context targeting high SES areas. Surveys on Students' Constitution and Health are conducted under the auspices of the Department of Education in Shandong Province, China. We thank all the team members and all participants. Special thanks are due to Mr. B Yu for providing access to the survey data.
17
18
Fig. 2. Mean values of WC for girls aged 7–18 years in different SES districts.
China is a developing country with highly unbalanced regional development. In this study, we found that children and adolescents in high SES districts had higher prevalence of abdominal obesity compared with those from moderate and low SES districts; this may be related to the regional difference in living conditions and lifestyle; children and adolescents in high SES districts have better access to energy-dense foods. Three limitations are noted. Firstly, a district (Zaozhuang) did not participate in the National Survey on Students' Constitution and Health; thus, the sample did not cover all districts of Shandong Province. Secondly, this study is a macro-analysis based on the regional SES; lacking individual SES information probably underestimated the true effects of SES on obesity. Thirdly, the absence of detailed information concerning living environments, nutritional status, dietary pattern, and physical activity at the individual level also limited our study.
[1] Wang Y, Lobstein T. Worldwide trends in childhood overweight and obesity. Int J Pediatr Obes 2006;1:11–25. [2] Wang Y. Cross-national comparison of childhood obesity: the epidemic and the relationship between obesity and socioeconomic status. Int J Epidemiol 2001; 30:1129–36. [3] McLaren L. Socioeconomic status and obesity. Epidemiol Rev 2007;29:29–48. [4] Shrewsbury V, Wardle J. Socioeconomic status and adiposity in childhood: a systematic review of cross-sectional studies 1990–2005. Obesity 2008;16:275–84. [5] Singh GK, Siahpush M, Kogan MD. Rising social inequalities in US childhood obesity, 2003–2007. Ann Epidemiol 2010;20:40–52. [6] Julia M, van Weissenbruch MM, de Waal HA, Surjono A. Influence of socioeconomic status on the prevalence of stunted growth and obesity in prepubertal Indonesian children. Food Nutr Bull 2004;25:354–60. [7] Silva DAS. Socioeconomic inequalities in abdominal obesity in Brazilian female adolescents: a national-based study. Eur J Pediatr 2013;172:1665–70. [8] Ji CY, Cheng TO. Prevalence and geographic distribution of childhood obesity in China in 2005. Int J Cardiol 2008;131:1–8. [9] Despres JP. Is visceral obesity the cause of the metabolic syndrome? Ann Med 2006;38:52–63. [10] Despres JP, Lemieux I. Abdominal obesity and metabolic syndrome. Nature 2006;444:881–7. [11] Zhang YX, Wang SR. Differences in development and the prevalence of obesity among children and adolescents in different socioeconomic status districts in Shandong, China. Ann Hum Biol 2012;39:290–6. [12] Shandong Provincial Bureau of Statistics. Shandong Statistical Yearbook. Beijing: China Statistical Publishing House; 2011 45 [in Chinese]. [13] Ji CY, Sung RYT, Ma GS, Ma J, He ZH, Chen TJ. Waist circumference distribution of Chinese school-age children and adolescents. Biomed Environ Sci 2010;23: 12–20.
Please cite this article as: Zhang Y, et al, Socioeconomic inequalities in abdominal obesity among children and adolescents in Shandong, China, Int J Cardiol (2014), http://dx.doi.org/10.1016/j.ijcard.2014.04.222
Contents lists available at ScienceDirect
International Journal of Cardiology journal homepage: www.elsevier.com/locate/ijcard
Letter to the Editor
Socioeconomic inequalities in abdominal obesity among children and adolescents in Shandong, China Ying-xiu Zhang ⁎, Jin-shan Zhao, Zun-hua Chu Shandong Center for Disease Control and Prevention, Shandong University Institute of Preventive Medicine, Shandong, China
a r t i c l e
i n f o
Article history: Received 14 April 2014 Accepted 17 April 2014 Available online xxxx Keywords: Abdominal obesity Prevalence Regional disparity Socioeconomic status Child and adolescent
The prevalence of childhood obesity is increasing rapidly worldwide [1]. Socioeconomic factors may play an important role in the development of obesity. Many previous studies have confirmed that the population distribution of childhood obesity is associated with socioeconomic status (SES) and that the patterns vary from country to country, depending on the degree of economic development of a country [2,3]. Studies from developed countries showed that high SES youths are less likely to be obese compared with their lower SES counterparts [4,5]. In contrast, in developing countries such as Indonesia, Brazil and China, high SES youths are more likely to be obese compared with their lower SES counterparts [6–8]. Abdominal fat distribution is associated with greater health risks than total body fat [9]. Recent evidence suggests that compared with overall obesity, abdominal obesity appears to be more strongly associated with cardiovascular disease (CVD) risk factors [10]. In this article, based on provincial data in 2010, we report the prevalence and regional disparities in abdominal obesity among children and adolescents in Shandong, China. Data for this study were obtained from a large cross-sectional survey of schoolchildren. A total of 42,234 students (21,192 boys and 21,042 girls) from 16 districts in Shandong Province, students of Han nationality, aged 7–18 years, participated in the National Surveys on Chinese Students' Constitution and Health, which were carried out in September ⁎ Corresponding author at: Shandong Center for Disease Control and Prevention, Shandong University Institute of Preventive Medicine, 16992 Jingshi Road, Jinan 250014, Shandong, China. Tel./fax: +86 531 82679413. E-mail address: [email protected] (Y. Zhang).
to October 2010. It is, so far, the largest representative sample of schoolaged children and adolescents in Shandong, China. All subjects voluntarily joined this study with informed consents. The sampling method was stratified multistage sampling based on selected primary and secondary schools and has been described in detail elsewhere [11]. The information about gross domestic product (GDP) per capita of the 16 districts in 2010 was collected from Shandong Statistical Yearbook [12]. The 16 districts were divided into three groups (high SES, moderate SES and low SES) according to their GDP per capita in 2010. High SES was defined as GDP per capita above 8000 dollars (including Jinan, Qingdao, Yantai, Weihai, Dongying and Zibo), moderate SES was defined as GDP per capita above 5000 but below 8000 dollars (including Weifang, Taian, Laiwu, Binzhou and Rizhao), and low SES was defined as GDP per capita below 5000 dollars (including Jining, Dezhou, Liaocheng, Linyi and Heze). All measurements were conducted by a team of trained technicians in each of the 16 districts. Each technician is required to pass a training course for anthropometric measurement organized by the investigation team in Shandong. Waist circumference (WC) was measured midway between the lowest rib and the superior border of the iliac crest with an inelastic measuring tape at the end of normal expiration to the nearest 0.1 cm. Abdominal obesity was defined by previously published WC references (≥ 90th percentile) based on Chinese national data [13]. The mean values of WC for boys and girls aged 7–18 years in different SES districts are shown in Figs. 1 and 2. We found that boys and girls in high SES districts had higher WC levels compared with their peers in moderate and low SES districts. The mean values of WC of children and adolescents aged 7 to 18 years in high SES districts were higher than in moderate and low SES districts by 1.08–2.11 cm and 1.86–3.15 cm for boys and 0.60–1.27 cm and 1.20–2.24 cm for girls. The overall prevalence of abdominal obesity among children and adolescents aged 7–18 years was 20.21% and 16.59% for boys and girls, respectively; χ2 tests indicated that boys had higher prevalence compared with girls (χ2 = 92.12, P b 0.01). The prevalence of abdominal obesity among children and adolescents by regional SES is shown in Table 1. An increasing trend was observed from the low SES group to the moderate and high SES groups. The overall prevalence rates of abdominal obesity in the three SES groups were 16.12%, 20.51% and 22.84% for boys and 15.47%, 16.66% and 17.34% for girls. For boys, statistical significant differences were observed between any two groups (P b 0.01). For girls, statistical significant differences were observed between the high and low SES groups (P b 0.01).
http://dx.doi.org/10.1016/j.ijcard.2014.04.222 0167-5273/© 2014 Elsevier Ireland Ltd. All rights reserved.
Please cite this article as: Zhang Y, et al, Socioeconomic inequalities in abdominal obesity among children and adolescents in Shandong, China, Int J Cardiol (2014), http://dx.doi.org/10.1016/j.ijcard.2014.04.222
2
Y. Zhang et al. / International Journal of Cardiology xxx (2014) xxx–xxx
80
Table 1 Prevalence of abdominal obesity among children and adolescents aged 7–18 years in different SES districts.
75
Groups
cm
70 High SES Moderate SES Low SES
65 High SES
60
Low SES
% (95% CI)
n
% (95% CI)
9050 5896 6246
22.84 (21.98–23.70) 20.51 (19.48–21.54) 16.12 (15.21–17.03) χ2 = 103.85, P = 0.000
8918 5853 6271
17.34 (16.55–18.13) 16.66 (15.71–17.61) 15.47 (14.57–16.37) χ2 = 9.31, P = 0.009
SES: socioeconomic status.
Age/years
7
8
9
10
11
12
13
14
15
16
17
18
Fig. 1. Mean values of WC for boys aged 7–18 years in different SES districts.
80 75 70
cm
Girls
n
Moderate SES
55 50
Boys
65
References
High SES
60
Moderate SES Low SES
55
Age/years
50 7
8
9
10
11
12
13
14
15
16
The present study further highlights that the prevalence of childhood abdominal obesity is wide in Shandong Province, one of the populous provinces in China. Abdominal obesity among children and adolescents is associated with affluence. Intervention and strategy for obesity should be based on this specific context targeting high SES areas. Surveys on Students' Constitution and Health are conducted under the auspices of the Department of Education in Shandong Province, China. We thank all the team members and all participants. Special thanks are due to Mr. B Yu for providing access to the survey data.
17
18
Fig. 2. Mean values of WC for girls aged 7–18 years in different SES districts.
China is a developing country with highly unbalanced regional development. In this study, we found that children and adolescents in high SES districts had higher prevalence of abdominal obesity compared with those from moderate and low SES districts; this may be related to the regional difference in living conditions and lifestyle; children and adolescents in high SES districts have better access to energy-dense foods. Three limitations are noted. Firstly, a district (Zaozhuang) did not participate in the National Survey on Students' Constitution and Health; thus, the sample did not cover all districts of Shandong Province. Secondly, this study is a macro-analysis based on the regional SES; lacking individual SES information probably underestimated the true effects of SES on obesity. Thirdly, the absence of detailed information concerning living environments, nutritional status, dietary pattern, and physical activity at the individual level also limited our study.
[1] Wang Y, Lobstein T. Worldwide trends in childhood overweight and obesity. Int J Pediatr Obes 2006;1:11–25. [2] Wang Y. Cross-national comparison of childhood obesity: the epidemic and the relationship between obesity and socioeconomic status. Int J Epidemiol 2001; 30:1129–36. [3] McLaren L. Socioeconomic status and obesity. Epidemiol Rev 2007;29:29–48. [4] Shrewsbury V, Wardle J. Socioeconomic status and adiposity in childhood: a systematic review of cross-sectional studies 1990–2005. Obesity 2008;16:275–84. [5] Singh GK, Siahpush M, Kogan MD. Rising social inequalities in US childhood obesity, 2003–2007. Ann Epidemiol 2010;20:40–52. [6] Julia M, van Weissenbruch MM, de Waal HA, Surjono A. Influence of socioeconomic status on the prevalence of stunted growth and obesity in prepubertal Indonesian children. Food Nutr Bull 2004;25:354–60. [7] Silva DAS. Socioeconomic inequalities in abdominal obesity in Brazilian female adolescents: a national-based study. Eur J Pediatr 2013;172:1665–70. [8] Ji CY, Cheng TO. Prevalence and geographic distribution of childhood obesity in China in 2005. Int J Cardiol 2008;131:1–8. [9] Despres JP. Is visceral obesity the cause of the metabolic syndrome? Ann Med 2006;38:52–63. [10] Despres JP, Lemieux I. Abdominal obesity and metabolic syndrome. Nature 2006;444:881–7. [11] Zhang YX, Wang SR. Differences in development and the prevalence of obesity among children and adolescents in different socioeconomic status districts in Shandong, China. Ann Hum Biol 2012;39:290–6. [12] Shandong Provincial Bureau of Statistics. Shandong Statistical Yearbook. Beijing: China Statistical Publishing House; 2011 45 [in Chinese]. [13] Ji CY, Sung RYT, Ma GS, Ma J, He ZH, Chen TJ. Waist circumference distribution of Chinese school-age children and adolescents. Biomed Environ Sci 2010;23: 12–20.
Please cite this article as: Zhang Y, et al, Socioeconomic inequalities in abdominal obesity among children and adolescents in Shandong, China, Int J Cardiol (2014), http://dx.doi.org/10.1016/j.ijcard.2014.04.222
