AMERICAN JOURNAL OF HUMAN BIOLOGY 27:417–420 (2015)
Short Report
Percentiles and Regional Distribution of Skinfold Thickness Among Children and Adolescents in Shandong, China YING-XIU ZHANG,* JIN-SHAN ZHAO, AND ZUN-HUA CHU Shandong Center for Disease Control and Prevention, Shandong University Institute of Preventive Medicine, Shandong, China
Objective: Skinfold thicknesses (SFT) have long been considered important and valid measurements of subcutaneous fat. The present study reported the percentiles and regional distribution of SFT among children and adolescents in Shandong, China. Methods: Data for this study were obtained from a large cross-sectional survey of schoolchildren. A total of 42,268 students (21,200 boys and 21,068 girls) aged 7–18 years from 16 districts participated in this study. Triceps, subscapular, and abdomen SFT of all subjects were measured. Results: Shandong children and adolescents had a high SFT level and substantial regional disparities in SFT were observed. Boys and girls resident in high socioeconomic status (SES) districts had higher SFT level than those living in moderate and low SES districts. Conclusion: The SFT level of children and adolescents is associated with regional SES in Shandong, China. This may be interpreted as a result of geographic variation between the districts in the process of urbanization, living standC 2014 Wiley V ards, nutritional conditions, dietary patterns, and public health. Am. J. Hum. Biol. 27:417–420, 2015. Periodicals, Inc.
Although body mass index (BMI) is widely used as a surrogate measure of adiposity, it does not distinguish between fat mass and fat-free mass, and its limitations are widely known (McCarthy et al., 2006; Prentice and Jebb, 2001). A number of different tools and methodologies have been developed to measure body composition, and skinfold thicknesses (SFT) have been shown to be closely correlated with total body fatness as well as with other nutrition and biochemical measures (Addo et al., 2012; Freedman et al., 2009). Furthermore, SFT measurements are noninvasive, simple, and less expensive than laboratory-based techniques, so they have been widely applied in large-scale epidemiological studies. Shandong Province, located in the lower reaches of the Yellow River, is an important littoral province in East China. It has a total area of 156,700 square kilometers and had a total population of 95.79 million in 2010. Little is known about the distribution of SFT among children and adolescents in this region. In this article, based on 2010 provincial data, we report the percentiles and regional distribution of SFT among children and adolescents in Shandong, China. SUBJECTS AND METHODS The study was approved by the Ethical Committee of the Shandong Center for Disease Control and Prevention, Shandong, China.
cents 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 (Zhang and Wang, 2012). Age groups were divided according to criteria of ‘exact age’, so that, for example, cohort 7.5 (represented by ‘7.5’ in the plots) designates students aged 7.0–7.9 years. Classification of subgroups The information about gross domestic product (GDP) per capita of the 16 districts in 2010 was collected from Shandong Statistical Yearbook (Shandong Provincial Bureau of Statistics, 2011). The 16 districts were divided into three groups [high socioeconomic status (SES), moderate SES and low SES] according to their GDP per capita in 2010. High SES was defined as GDP per capita above 8,000 dollars (including Jinan, Qingdao, Yantai, Weihai, Dongying, and Zibo). Moderate SES was defined as GDP per capita above 5,000 but below 8,000 dollars (including Weifang, Taian, Laiwu, Binzhou, and Rizhao), and low SES was defined as GDP per capita below 5,000 dollars (including Jining, Dezhou, Liaocheng, Linyi, and Heze). Measurements
Study population
All measurements were performed by well-trained health professionals in each of the 16 districts using the same type of apparatus and following the same procedures. SFT were measured on the right side of the body
Data for this study were obtained from a large crosssectional survey of schoolchildren. A total of 42,268 students (21,200 boys and 21,068 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 to October, 2010. It is, so far, the largest representative sample of school-aged children and adoles-
*Correspondence to: Ying-Xiu Zhang, Shandong Center for Disease Control and Prevention, Shandong University Institute of Preventive Medicine, 16992 Jingshi Road, Jinan 250014, Shandong, China. E-mail: [email protected] Received 16 June 2014; Revision received 29 July 2014; Accepted 4 September 2014 DOI: 10.1002/ajhb.22628 Published online 3 October 2014 in Wiley Online Library (wileyonlinelibrary.com).
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52.0 58.0 65.0 71.5 75.5 71.5 66.5 60.0 57.0 63.0 67.0 65.0 51.0 55.5 61.5 63.0 66.0 64.3 68.5 70.2 69.4 72.5 76.0 76.0 43.0 45.0 50.0 57.5 60.5 58.0 54.0 49.9 47.4 52.0 53.0 55.5 43.3 41.5 49.0 52.0 54.7 55.5 58.0 61.5 61.0 65.0 66.6 67.5 25.0 28.0 31.5 36.0 38.0 37.0 33.4 33.0 33.0 37.0 38.8 37.5 26.5 29.0 32.5 37.0 39.0 41.6 45.5 49.0 52.0 54.0 55.0 55.5 15.0 15.5 16.0 17.0 18.5 21.5 21.0 20.0 21.0 22.0 23.0 23.0 16.5 16.5 19.0 19.5 21.0 26.0 28.5 31.5 31.5 38.0 40.0 39.8 20.0 22.0 25.0 27.5 29.0 28.0 27.0 24.0 23.0 25.0 28.0 28.0 20.0 20.6 23.0 24.0 25.0 25.4 27.0 27.5 27.4 29.0 30.0 29.0 16.0 18.0 19.0 22.2 23.0 22.0 20.0 18.0 18.0 19.5 20.5 20.0 16.5 17.0 19.0 19.5 20.0 20.0 20.0 21.6 21.5 22.9 24.3 24.5 12.0 13.0 15.0 17.0 18.0 17.0 16.0 14.9 14.6 16.0 16.0 17.0 13.0 12.0 14.0 16.0 16.5 16.7 17.5 18.6 19.0 20.0 21.0 21.0
4.5 4.5 5.0 5.3 5.5 7.0 7.0 6.5 7.0 7.0 8.0 7.5 4.6 4.5 5.5 6.0 6.5 9.0 10.0 11.0 11.0 13.5 14.0 13.3
5.0 5.5 6.0 7.0 7.5 9.0 8.0 8.0 8.5 9.0 10.0 9.5 5.5 5.5 7.0 7.5 9.0 10.5 11.5 13.0 13.0 15.0 16.0 16.0
8.5 9.5 11.0 12.6 14.0 14.0 12.0 12.0 12.0 14.0 14.0 14.0 9.0 9.0 11.0 12.5 14.0 15.0 16.0 17.5 18.5 19.5 20.2 20.4
15.0 17.0 19.0 22.0 23.0 22.0 20.0 19.0 19.0 21.0 21.5 21.5 15.0 15.0 18.0 19.4 20.0 21.0 22.0 23.6 23.5 25.0 26.0 25.5
17.5 19.0 20.0 22.0 24.0 25.5 24.0 23.5 24.5 26.0 27.5 27.0 19.0 20.0 22.5 23.6 25.5 30.5 33.0 37.0 38.0 42.0 44.3 44.1
50th 25th 15th 85th 75th 50th 85th 75th
15th
25th
Fig. 1. The 50th percentile curves for SSFT of Shandong and Chinese adolescents in 2010.
using a skinfold caliper (Minjian, GMCS-PZQ; Beijing Xindong Huateng Sports Instruments Company) to the nearest 0.5 mm, at the three sites: (i) triceps, halfway between the acromion process and the olecranon process; (ii) subscapular, 1.0 cm below the tip of the scapula, at an angle of 45 to the lateral side of the body; (iii) abdomen, intersection of right midclavicular line, and navel horizontal line, the fold is lifted parallel to the long axis of the body. In each participant, three measurements were taken and the middle value was recorded for one skinfold site. The sum of triceps, subscapular, and abdomen skinfold thickness (SSFT) was analyzed.
7.0 8.0 9.0 10.0 10.5 10.9 10.0 10.0 10.0 11.0 12.0 12.0 7.0 7.5 9.0 9.8 11.0 12.0 13.0 14.0 15.0 15.5 16.0 17.0 5.0 5.5 5.5 6.0 6.5 7.0 7.0 7.5 8.0 8.5 9.0 9.5 5.5 5.5 6.0 6.3 7.0 9.0 9.5 10.0 11.0 12.0 13.0 13.0 4.5 5.0 5.0 5.0 5.0 6.0 6.1 6.5 7.0 7.5 8.0 8.0 5.0 5.0 5.0 5.0 6.0 7.0 8.0 9.0 9.1 11.0 11.5 11.5 16.5 19.0 20.0 22.3 23.0 22.5 20.0 20.0 17.5 20.0 19.0 20.0 17.0 18.5 20.0 20.5 21.0 21.0 21.5 23.0 22.5 23.5 24.0 25.0
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Girls
7.5 8.5 9.5 10.5 11.5 12.5 13.5 14.5 15.5 16.5 17.5 18.5 7.5 8.5 9.5 10.5 11.5 12.5 13.5 14.5 15.5 16.5 17.5 18.5
1751 1892 1735 1807 1792 1781 1758 1672 1808 1715 1735 1754 1782 1814 1819 1824 1753 1720 1759 1703 1782 1681 1722 1709
6.0 6.0 6.0 6.5 7.0 7.5 7.0 6.0 6.0 6.0 6.0 6.0 6.5 6.5 7.0 7.0 7.0 9.0 10.0 10.0 10.0 11.5 12.0 12.0
7.0 7.4 8.0 8.5 9.0 9.0 8.0 7.2 7.4 8.0 7.5 7.5 8.0 8.0 9.0 9.0 9.5 10.5 11.0 12.0 12.2 13.5 14.0 14.0
10.0 11.0 11.0 13.0 14.0 13.5 11.1 11.0 10.2 11.0 11.5 11.0 10.5 11.0 12.0 13.0 14.0 14.0 15.0 16.0 16.5 17.5 17.5 17.5
14.0 15.5 16.5 19.0 19.5 19.0 16.0 16.0 15.0 16.0 15.6 16.0 15.0 15.0 16.5 17.5 18.0 18.5 19.0 20.5 20.5 21.0 21.0 21.9
25th 15th Gender
Age/years
N
15th
25th
50th
75th
85th
50th
Statistical analyses
Boys
Abdomen Subscapular Triceps
TABLE 1. Percentile values for skinfold thickness (SFT) of Shandong Chinese children and adolescents by gender and age in 2010 (mm)
SFT sum
75th
85th
Y.-X. ZHANG ET AL
SFT levels of children and adolescents were presented as percentiles by age group and gender, and the 50th percentile of SSFT in different SES districts were compared by Kruskal–Wallis analyses. All analyses were performed with the statistical package SPSS/PC 1 version 11.5. RESULTS Percentiles of SFT The percentile values of triceps, subscapular and abdomen SFT by age and gender in the sample are shown in Table 1. The 50th percentile values of SFT increased in a gender-specific pattern with age. In girls, the 50th percentiles of triceps, subscapular, and abdomen SFT increased with the age, from 10.5, 7.0, and 9.0 mm at 7 years to 17.5, 17.0, and 20.4 mm at 18 years, respectively. In boys, age-dependent changes were more complex. The 50th percentiles of triceps SFT increased from 10.0 mm (7 years) to 14.0 mm (11 years), then decreased to 10.2 mm (15 years), and then slightly increased to 11.0 mm at 18 years; subscapular SFT increased from 7.0 mm (7 years) to 10.9 mm (12 years), then decreased to 10.0 mm (15 years), and then slightly increased to 12.0 mm at 18 years; abdomen SFT increased from 8.5 mm (7 years) to 14.0 mm (12 years), then decreased to 12.0 mm (15 years), and then slightly increased to 14.0 mm at 18 years. Girls had higher SFT than peer boys after entering puberty. For example, the 50th percentiles of SSFT in girls aged 13–18 years were higher than boys by 12.1–19.0 mm, at rates of 36–57%. Comparing the reference values of 50th percentile for Chinese children and adolescents (Research Section of the
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Fig. 2. The 50th percentile for SSFT of boys (a) and girls (b) aged 7–18 years in different socioeconomic status (SES) districts in Shandong, China, 2010.
Constitution and Health of Chinese Students, 2012), we found that the 50th percentiles of SSFT for Shandong children and adolescents were higher than the reference values (Fig. 1). The 50th percentiles of SSFT for children and adolescents aged 7–18 years in Shandong are above the reference values for Chinese children and adolescents by 3.5–6.5 mm (at rates of 12–23%) for boys and 2.0– 4.5 mm (at rates of 4–16%) for girls, respectively. Regional distribution of SFT The 50th percentile for SSFT of children and adolescents in different SES districts are shown in Figure 2. An increasing trend was observed from the low SES district to the moderate and high SES districts in all age groups (7–18 years). For boys, the 50th percentiles of SSFT of children and adolescents aged 7–18 years in high SES district were higher than moderate and low SES districts by 2.5–3.6 mm (at rates of 7–14%) and 5.6–8.0 mm (at rates of 18–27%), respectively. For girls, these figures were 2.2– 3.2 mm (at rates of 4–12%) and 6.0–8.9 mm (at rates of 15–26%), respectively.
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 SES and that the patterns vary from country to country, depending on the degree of economic development of a country (McLaren, 2007). Studies from developed countries showed that high SES youths are less likely to be obese than their lower SES counterparts (Shrewsbury and Wardle, 2008; Singh et al., 2010). In contrast, in developing countries, such as Indonesia, Brazil, and China, high SES youths are more likely to be obese than their lower SES counterparts (Ji and Cheng, 2008; Julia et al., 2004; Silva, 2013). We have reported that children and adolescents from high SES districts were taller, heavier, and more likely to be obese than their peers from moderate and low SES in Shandong, China (Zhang and Wang, 2012). This study indicated that boys and girls resident in high SES district had higher SFT level than those living in moderate and low SES districts, and this may be related to the difference in living conditions and lifestyle. Children and adolescents in high SES district have better access to energy-dense foods. The major strength of this study is that, based on the data from a large population, the distribution and regional disparities in SFT among children and adolescents are examined. However, this study has two limitations. First, 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 macroanalysis based on the regional SES. The absence of detailed information concerning living environments, nutritional status, dietary pattern, and physical activity at the individual level limited our study. In summary, the distributions of SFT for children and adolescents were examined for the first time in Shandong, one of the populous provinces in China. Shandong children and adolescents had a high SFT level and the SFT level was associated with regional SES. This may be interpreted as a result of geographic variation between the districts in the process of urbanization, living standards, nutritional conditions, dietary patterns, and public health. ACKNOWLEDGMENTS 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 to Mr. B. Yu for providing access to the survey data.
DISCUSSION
LITERATURE CITED
The national data confirmed that Shandong province is one of the areas of China with higher prevalences of overweight and obesity among children and adolescents (Ji and Cheng, 2008). In this study, we found that Shandong children and adolescents had a high SFT level, with the 50th percentiles of SFT of children and adolescents aged 7–18 years in Shandong being above the reference values for Chinese children and adolescents by 3.5–6.5 mm for boys and 2.0–4.5 mm for girls. This is consistent with the high prevalence of overweight and obesity among children and adolescents in Shandong.
Addo OY, Pereira MA, Himes JH. 2012. Comparability of skinfold thickness to DXA whole-body total fat in their associations with serum triglycerides in youths. Eur J Clin Nutr 66:989–993. Freedman DS, Katzmarzyk PT, Dietz WH, Srinivasan SR, Berenson GS. 2009. Relation of body mass index and skinfold thicknesses to cardiovascular disease risk factors in children: the Bogalusa Heart Study. Am J Clin Nutr 90:210–216. Ji CY, Cheng TO. 2008. Prevalence and geographic distribution of childhood obesity in China in 2005. Int J Cardiol 131:1–8. Julia M, van Weissenbruch MM, de Waal HA, Surjono A. 2004. Influence of socioeconomic status on the prevalence of stunted growth and obesity in prepubertal Indonesian children. Food Nutr Bull 25:354–360. McCarthy HD, Cole TJ, Fry T, Jebb SA, Prentice AM. 2006. Body fat reference curves for children. Int J Obes 30:598–602.
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McLaren L. 2007. Socioeconomic status and obesity. Epidemiol Rev 29:29– 48. Prentice AM, Jebb SA. 2001. Beyond body mass index. Obes Rev 2:141– 147. Research Section of the Constitution and Health of Chinese Students (RSCHCS). 2012. Report on the physical fitness and health research of Chinese school students. Beijing: Higher Education Press. p 110–121 [in Chinese]. Shandong Provincial Bureau of Statistics. 2011. Shandong Statistical Yearbook. Beijing: China Statistical Publishing House. p 45 [in Chinese].
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Shrewsbury V, Wardle J. 2008. Socioeconomic status and adiposity in childhood: a systematic review of cross-sectional studies 1990–2005. Obesity 16:275–284. Silva DAS. 2013. Socioeconomic inequalities in abdominal obesity in Brazilian female adolescents: a national-based study. Eur J Pediatr 172: 1665–1670. Singh GK, Siahpush M, Kogan MD. 2010. Rising social inequalities in US childhood obesity, 2003–2007. Ann Epidemiol 20:40–52. Zhang YX, Wang SR. 2012. Differences in development and the prevalence of obesity among children and adolescents in different socioeconomic status districts in Shandong, China. Ann Hum Biol 39:290–296.
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Short Report
Percentiles and Regional Distribution of Skinfold Thickness Among Children and Adolescents in Shandong, China YING-XIU ZHANG,* JIN-SHAN ZHAO, AND ZUN-HUA CHU Shandong Center for Disease Control and Prevention, Shandong University Institute of Preventive Medicine, Shandong, China
Objective: Skinfold thicknesses (SFT) have long been considered important and valid measurements of subcutaneous fat. The present study reported the percentiles and regional distribution of SFT among children and adolescents in Shandong, China. Methods: Data for this study were obtained from a large cross-sectional survey of schoolchildren. A total of 42,268 students (21,200 boys and 21,068 girls) aged 7–18 years from 16 districts participated in this study. Triceps, subscapular, and abdomen SFT of all subjects were measured. Results: Shandong children and adolescents had a high SFT level and substantial regional disparities in SFT were observed. Boys and girls resident in high socioeconomic status (SES) districts had higher SFT level than those living in moderate and low SES districts. Conclusion: The SFT level of children and adolescents is associated with regional SES in Shandong, China. This may be interpreted as a result of geographic variation between the districts in the process of urbanization, living standC 2014 Wiley V ards, nutritional conditions, dietary patterns, and public health. Am. J. Hum. Biol. 27:417–420, 2015. Periodicals, Inc.
Although body mass index (BMI) is widely used as a surrogate measure of adiposity, it does not distinguish between fat mass and fat-free mass, and its limitations are widely known (McCarthy et al., 2006; Prentice and Jebb, 2001). A number of different tools and methodologies have been developed to measure body composition, and skinfold thicknesses (SFT) have been shown to be closely correlated with total body fatness as well as with other nutrition and biochemical measures (Addo et al., 2012; Freedman et al., 2009). Furthermore, SFT measurements are noninvasive, simple, and less expensive than laboratory-based techniques, so they have been widely applied in large-scale epidemiological studies. Shandong Province, located in the lower reaches of the Yellow River, is an important littoral province in East China. It has a total area of 156,700 square kilometers and had a total population of 95.79 million in 2010. Little is known about the distribution of SFT among children and adolescents in this region. In this article, based on 2010 provincial data, we report the percentiles and regional distribution of SFT among children and adolescents in Shandong, China. SUBJECTS AND METHODS The study was approved by the Ethical Committee of the Shandong Center for Disease Control and Prevention, Shandong, China.
cents 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 (Zhang and Wang, 2012). Age groups were divided according to criteria of ‘exact age’, so that, for example, cohort 7.5 (represented by ‘7.5’ in the plots) designates students aged 7.0–7.9 years. Classification of subgroups The information about gross domestic product (GDP) per capita of the 16 districts in 2010 was collected from Shandong Statistical Yearbook (Shandong Provincial Bureau of Statistics, 2011). The 16 districts were divided into three groups [high socioeconomic status (SES), moderate SES and low SES] according to their GDP per capita in 2010. High SES was defined as GDP per capita above 8,000 dollars (including Jinan, Qingdao, Yantai, Weihai, Dongying, and Zibo). Moderate SES was defined as GDP per capita above 5,000 but below 8,000 dollars (including Weifang, Taian, Laiwu, Binzhou, and Rizhao), and low SES was defined as GDP per capita below 5,000 dollars (including Jining, Dezhou, Liaocheng, Linyi, and Heze). Measurements
Study population
All measurements were performed by well-trained health professionals in each of the 16 districts using the same type of apparatus and following the same procedures. SFT were measured on the right side of the body
Data for this study were obtained from a large crosssectional survey of schoolchildren. A total of 42,268 students (21,200 boys and 21,068 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 to October, 2010. It is, so far, the largest representative sample of school-aged children and adoles-
*Correspondence to: Ying-Xiu Zhang, Shandong Center for Disease Control and Prevention, Shandong University Institute of Preventive Medicine, 16992 Jingshi Road, Jinan 250014, Shandong, China. E-mail: [email protected] Received 16 June 2014; Revision received 29 July 2014; Accepted 4 September 2014 DOI: 10.1002/ajhb.22628 Published online 3 October 2014 in Wiley Online Library (wileyonlinelibrary.com).
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52.0 58.0 65.0 71.5 75.5 71.5 66.5 60.0 57.0 63.0 67.0 65.0 51.0 55.5 61.5 63.0 66.0 64.3 68.5 70.2 69.4 72.5 76.0 76.0 43.0 45.0 50.0 57.5 60.5 58.0 54.0 49.9 47.4 52.0 53.0 55.5 43.3 41.5 49.0 52.0 54.7 55.5 58.0 61.5 61.0 65.0 66.6 67.5 25.0 28.0 31.5 36.0 38.0 37.0 33.4 33.0 33.0 37.0 38.8 37.5 26.5 29.0 32.5 37.0 39.0 41.6 45.5 49.0 52.0 54.0 55.0 55.5 15.0 15.5 16.0 17.0 18.5 21.5 21.0 20.0 21.0 22.0 23.0 23.0 16.5 16.5 19.0 19.5 21.0 26.0 28.5 31.5 31.5 38.0 40.0 39.8 20.0 22.0 25.0 27.5 29.0 28.0 27.0 24.0 23.0 25.0 28.0 28.0 20.0 20.6 23.0 24.0 25.0 25.4 27.0 27.5 27.4 29.0 30.0 29.0 16.0 18.0 19.0 22.2 23.0 22.0 20.0 18.0 18.0 19.5 20.5 20.0 16.5 17.0 19.0 19.5 20.0 20.0 20.0 21.6 21.5 22.9 24.3 24.5 12.0 13.0 15.0 17.0 18.0 17.0 16.0 14.9 14.6 16.0 16.0 17.0 13.0 12.0 14.0 16.0 16.5 16.7 17.5 18.6 19.0 20.0 21.0 21.0
4.5 4.5 5.0 5.3 5.5 7.0 7.0 6.5 7.0 7.0 8.0 7.5 4.6 4.5 5.5 6.0 6.5 9.0 10.0 11.0 11.0 13.5 14.0 13.3
5.0 5.5 6.0 7.0 7.5 9.0 8.0 8.0 8.5 9.0 10.0 9.5 5.5 5.5 7.0 7.5 9.0 10.5 11.5 13.0 13.0 15.0 16.0 16.0
8.5 9.5 11.0 12.6 14.0 14.0 12.0 12.0 12.0 14.0 14.0 14.0 9.0 9.0 11.0 12.5 14.0 15.0 16.0 17.5 18.5 19.5 20.2 20.4
15.0 17.0 19.0 22.0 23.0 22.0 20.0 19.0 19.0 21.0 21.5 21.5 15.0 15.0 18.0 19.4 20.0 21.0 22.0 23.6 23.5 25.0 26.0 25.5
17.5 19.0 20.0 22.0 24.0 25.5 24.0 23.5 24.5 26.0 27.5 27.0 19.0 20.0 22.5 23.6 25.5 30.5 33.0 37.0 38.0 42.0 44.3 44.1
50th 25th 15th 85th 75th 50th 85th 75th
15th
25th
Fig. 1. The 50th percentile curves for SSFT of Shandong and Chinese adolescents in 2010.
using a skinfold caliper (Minjian, GMCS-PZQ; Beijing Xindong Huateng Sports Instruments Company) to the nearest 0.5 mm, at the three sites: (i) triceps, halfway between the acromion process and the olecranon process; (ii) subscapular, 1.0 cm below the tip of the scapula, at an angle of 45 to the lateral side of the body; (iii) abdomen, intersection of right midclavicular line, and navel horizontal line, the fold is lifted parallel to the long axis of the body. In each participant, three measurements were taken and the middle value was recorded for one skinfold site. The sum of triceps, subscapular, and abdomen skinfold thickness (SSFT) was analyzed.
7.0 8.0 9.0 10.0 10.5 10.9 10.0 10.0 10.0 11.0 12.0 12.0 7.0 7.5 9.0 9.8 11.0 12.0 13.0 14.0 15.0 15.5 16.0 17.0 5.0 5.5 5.5 6.0 6.5 7.0 7.0 7.5 8.0 8.5 9.0 9.5 5.5 5.5 6.0 6.3 7.0 9.0 9.5 10.0 11.0 12.0 13.0 13.0 4.5 5.0 5.0 5.0 5.0 6.0 6.1 6.5 7.0 7.5 8.0 8.0 5.0 5.0 5.0 5.0 6.0 7.0 8.0 9.0 9.1 11.0 11.5 11.5 16.5 19.0 20.0 22.3 23.0 22.5 20.0 20.0 17.5 20.0 19.0 20.0 17.0 18.5 20.0 20.5 21.0 21.0 21.5 23.0 22.5 23.5 24.0 25.0
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Girls
7.5 8.5 9.5 10.5 11.5 12.5 13.5 14.5 15.5 16.5 17.5 18.5 7.5 8.5 9.5 10.5 11.5 12.5 13.5 14.5 15.5 16.5 17.5 18.5
1751 1892 1735 1807 1792 1781 1758 1672 1808 1715 1735 1754 1782 1814 1819 1824 1753 1720 1759 1703 1782 1681 1722 1709
6.0 6.0 6.0 6.5 7.0 7.5 7.0 6.0 6.0 6.0 6.0 6.0 6.5 6.5 7.0 7.0 7.0 9.0 10.0 10.0 10.0 11.5 12.0 12.0
7.0 7.4 8.0 8.5 9.0 9.0 8.0 7.2 7.4 8.0 7.5 7.5 8.0 8.0 9.0 9.0 9.5 10.5 11.0 12.0 12.2 13.5 14.0 14.0
10.0 11.0 11.0 13.0 14.0 13.5 11.1 11.0 10.2 11.0 11.5 11.0 10.5 11.0 12.0 13.0 14.0 14.0 15.0 16.0 16.5 17.5 17.5 17.5
14.0 15.5 16.5 19.0 19.5 19.0 16.0 16.0 15.0 16.0 15.6 16.0 15.0 15.0 16.5 17.5 18.0 18.5 19.0 20.5 20.5 21.0 21.0 21.9
25th 15th Gender
Age/years
N
15th
25th
50th
75th
85th
50th
Statistical analyses
Boys
Abdomen Subscapular Triceps
TABLE 1. Percentile values for skinfold thickness (SFT) of Shandong Chinese children and adolescents by gender and age in 2010 (mm)
SFT sum
75th
85th
Y.-X. ZHANG ET AL
SFT levels of children and adolescents were presented as percentiles by age group and gender, and the 50th percentile of SSFT in different SES districts were compared by Kruskal–Wallis analyses. All analyses were performed with the statistical package SPSS/PC 1 version 11.5. RESULTS Percentiles of SFT The percentile values of triceps, subscapular and abdomen SFT by age and gender in the sample are shown in Table 1. The 50th percentile values of SFT increased in a gender-specific pattern with age. In girls, the 50th percentiles of triceps, subscapular, and abdomen SFT increased with the age, from 10.5, 7.0, and 9.0 mm at 7 years to 17.5, 17.0, and 20.4 mm at 18 years, respectively. In boys, age-dependent changes were more complex. The 50th percentiles of triceps SFT increased from 10.0 mm (7 years) to 14.0 mm (11 years), then decreased to 10.2 mm (15 years), and then slightly increased to 11.0 mm at 18 years; subscapular SFT increased from 7.0 mm (7 years) to 10.9 mm (12 years), then decreased to 10.0 mm (15 years), and then slightly increased to 12.0 mm at 18 years; abdomen SFT increased from 8.5 mm (7 years) to 14.0 mm (12 years), then decreased to 12.0 mm (15 years), and then slightly increased to 14.0 mm at 18 years. Girls had higher SFT than peer boys after entering puberty. For example, the 50th percentiles of SSFT in girls aged 13–18 years were higher than boys by 12.1–19.0 mm, at rates of 36–57%. Comparing the reference values of 50th percentile for Chinese children and adolescents (Research Section of the
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Fig. 2. The 50th percentile for SSFT of boys (a) and girls (b) aged 7–18 years in different socioeconomic status (SES) districts in Shandong, China, 2010.
Constitution and Health of Chinese Students, 2012), we found that the 50th percentiles of SSFT for Shandong children and adolescents were higher than the reference values (Fig. 1). The 50th percentiles of SSFT for children and adolescents aged 7–18 years in Shandong are above the reference values for Chinese children and adolescents by 3.5–6.5 mm (at rates of 12–23%) for boys and 2.0– 4.5 mm (at rates of 4–16%) for girls, respectively. Regional distribution of SFT The 50th percentile for SSFT of children and adolescents in different SES districts are shown in Figure 2. An increasing trend was observed from the low SES district to the moderate and high SES districts in all age groups (7–18 years). For boys, the 50th percentiles of SSFT of children and adolescents aged 7–18 years in high SES district were higher than moderate and low SES districts by 2.5–3.6 mm (at rates of 7–14%) and 5.6–8.0 mm (at rates of 18–27%), respectively. For girls, these figures were 2.2– 3.2 mm (at rates of 4–12%) and 6.0–8.9 mm (at rates of 15–26%), respectively.
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 SES and that the patterns vary from country to country, depending on the degree of economic development of a country (McLaren, 2007). Studies from developed countries showed that high SES youths are less likely to be obese than their lower SES counterparts (Shrewsbury and Wardle, 2008; Singh et al., 2010). In contrast, in developing countries, such as Indonesia, Brazil, and China, high SES youths are more likely to be obese than their lower SES counterparts (Ji and Cheng, 2008; Julia et al., 2004; Silva, 2013). We have reported that children and adolescents from high SES districts were taller, heavier, and more likely to be obese than their peers from moderate and low SES in Shandong, China (Zhang and Wang, 2012). This study indicated that boys and girls resident in high SES district had higher SFT level than those living in moderate and low SES districts, and this may be related to the difference in living conditions and lifestyle. Children and adolescents in high SES district have better access to energy-dense foods. The major strength of this study is that, based on the data from a large population, the distribution and regional disparities in SFT among children and adolescents are examined. However, this study has two limitations. First, 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 macroanalysis based on the regional SES. The absence of detailed information concerning living environments, nutritional status, dietary pattern, and physical activity at the individual level limited our study. In summary, the distributions of SFT for children and adolescents were examined for the first time in Shandong, one of the populous provinces in China. Shandong children and adolescents had a high SFT level and the SFT level was associated with regional SES. This may be interpreted as a result of geographic variation between the districts in the process of urbanization, living standards, nutritional conditions, dietary patterns, and public health. ACKNOWLEDGMENTS 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 to Mr. B. Yu for providing access to the survey data.
DISCUSSION
LITERATURE CITED
The national data confirmed that Shandong province is one of the areas of China with higher prevalences of overweight and obesity among children and adolescents (Ji and Cheng, 2008). In this study, we found that Shandong children and adolescents had a high SFT level, with the 50th percentiles of SFT of children and adolescents aged 7–18 years in Shandong being above the reference values for Chinese children and adolescents by 3.5–6.5 mm for boys and 2.0–4.5 mm for girls. This is consistent with the high prevalence of overweight and obesity among children and adolescents in Shandong.
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