462
Letters to the Editor
Synchronous prevalence of obesity and elevated blood pressure among children and adolescents in Shandong, China Ying-xiu Zhang ⁎, Jing-yang Zhou, Jin-shan Zhao 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 11 March 2014 Accepted 2 April 2014 Available online 13 April 2014 Keywords: Overweight Obesity Elevated blood pressure Prevalence Adolescent
The worldwide prevalence of hypertension in adults has become a major public health problem, since it is the main risk factor for cardiovascular disease (CVD), accounting for nearly 45% of global CVD morbidity and mortality [1]. Importantly, several epidemiological studies have provided ample evidence that hypertension in adults has its onset in childhood; children with elevated blood pressure (BP) are more likely to become hypertensive adults [2–5]. Therefore, elevated BP in childhood was a predictor of hypertension in adulthood and contributes to the current epidemic of CVD. Unfortunately, the prevalence of high BP in the pediatric population is rising, and the increase is believed to be related to the epidemic of childhood obesity [6,7]. Based on these observations, early detection and intervention in children with elevated BP is an important action for the control and prevention of hypertension in adulthood. China is the largest developing country in the world, and has now joined the world epidemic of obesity with its rapid economic growth and urbanization [8]. In 2010, it was estimated that 9.9% and 5.1% of Chinese school-aged children and adolescents were overweight and obese, representing an estimated 30.43 million individuals [9]. In this article, we report the prevalence of obesity and elevated BP among children and adolescents in Shandong, China. Data for this study were obtained from a cross-sectional survey of schoolchildren which was carried out in October 2012. A total of 15,966 students (7959 boys and 8007 girls) from 7 districts in Shandong Province, students of Han nationality, aged 7–17 years, participated in this study. All subjects voluntarily joined this study with informed
consents. The sampling method was stratified multistage sampling based on selected primary and secondary schools. Six public schools (two primary schools, two junior high schools, and two senior high schools) from each of the 7 districts in Shandong were randomly selected and invited to participate in the study. From the selected schools, two classes in each grade were selected, and all students of the selected classes were invited to join the study. All measurements were conducted by a team of trained technicians in each of the 7 districts. All measurements were taken using the same type of apparatus and followed the same procedures. Height without shoes was measured using metal column height-measuring stands to the nearest 0.1 cm. Weight was measured using lever scales to the nearest 0.1 kg while the subjects wore their underwear only. Systolic blood pressure (SBP) and diastolic blood pressure (DBP) were measured using a mercury sphygmomanometer after each subject had rested for at least 15 min in a sitting position. BP was measured twice on the right arm with an appropriately sized cuff and the average value was recorded on the study form. DBP was defined via Korotkoff Sound 5. Body mass index (BMI) was calculated from their height and weight (kg/m2). The age- and gender-specific BMI cutoff points recommended by the Working Group on Obesity in China were used to define overweight and obesity [10]. Relatively high BP status was defined as SBP and/or DBP ≥ 95th percentile for age and gender [11]. The prevalence of overweight, obesity and relatively high BP among children and adolescents in the sample are shown in Table 1. The overall prevalence of overweight, obesity and relatively high BP were 15.28%, 12.88% and 19.55% for boys, and 10.28%, 6.53% and 15.85% for girls; χ2 tests indicated that all the figures of boys were significantly higher than girls (P b 0.01). For both boys and girls, adolescents (aged 13–17 years) had higher prevalence of relatively high BP and lower prevalence of combined overweight and obesity than children (aged 7–12 years) (P b 0.01). Significant regional differences in the prevalence of overweight, obesity and relatively high BP were observed. For boys, the prevalence of relatively high BP and combined overweight and obesity varied from 24.77% and 35.88% in Jinan to 11.55% and 18.18% in Weifang, and for girls, from 21.38% and 21.75% in Jinan to 10.42% and 11.89% in Linyi. More interestingly, we found that the prevalence of relatively high BP increased with the combined overweight and obesity in the seven
Table 1 Prevalence of overweight, obesity and relatively high BP among children and adolescents aged 7–17 years, (%). Gender Boys
Girls
Age/years 7–17 7–12 13–17 7–17 7–12 13–17
n
Ov (95% CI)
Ob (95% CI)
Ov + Ob (95% CI)
RHBP (95% CI)
7959 4436 3523 8007 4454 3553
15.28 (14.49–16.07)⁎ 16.59 (15.50–17.68)⁎ 13.62 (12.49–14.75)⁎,⁎⁎ 10.28 (9.61–10.95) 9.97 (9.09–10.85) 10.67 (9.65–11.69)
12.88 (12.14–13.62)⁎ 16.48 (15.39–17.57)⁎ 8.35 (7.44–9.26)⁎,⁎⁎
28.16 (27.17–29.15)⁎ 33.07 (31.69–34.45)⁎ 21.97 (20.60–23.34)⁎,⁎⁎
19.55 13.64 26.99 15.85 13.36 18.97
Ov, overweight. Ob, obesity. RHBP, relatively high blood pressure. ⁎ P b 0.01 for gender difference. ⁎⁎ P b 0.01 compared with 7–12 year old group.
⁎ 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).
6.53 (5.99–7.07) 8.94 (8.10–9.78) 3.52 (2.91–4.13)⁎⁎
16.81 (15.99–17.63) 18.90 (17.75–20.05) 14.19 (13.04–15.34)⁎⁎
(18.68–20.42)⁎ (12.63–14.65) (25.52–28.46)⁎,⁎⁎ (15.05–16.65) (12.36–14.36) (17.68–20.26)⁎⁎
Letters to the Editor
463
Fig. 1. Prevalence of relatively high BP and combined overweight and obesity among boys aged 7–17 years in seven districts.
Fig. 2. Prevalence of relatively high BP and combined overweight and obesity among girls aged 7–17 years in seven districts.
districts. The correlation coefficient were 0.988 for boys and 0.974 for girls (P b 0.01). The synchronous prevalent trends are shown in Figs. 1 and 2. The higher prevalence of relatively high BP in Shandong children and adolescents may be related to the physical characteristics and dietary customs of Shandongese. For example, within China, children and adolescents in Shandong had higher BMI and BP levels. A survey carried out in 2011 shown that per capita daily intake of salt was 12.5 g in the Shandong population, 2-times greater than the recommended nutrient intake [12]. Two limitations are noted. First, BP measurement at a single visit usually overestimates hypertension prevalence; however, the purpose of using BP categories in the analysis was to obtain a general idea of the extent of elevated BP in the studied adolescents rather than to diagnose the presence of hypertension among them. Thus, in this paper, we use the term ‘relative high BP’ rather than ‘high BP’. Second, the absence of detailed information concerning living environments, nutritional status, dietary pattern, and physical activity at the individual level also limited our study. The present study further highlights that there is prevalence of childhood overweight/obesity and elevated BP in Shandong Province, one of the populous provinces in China. The ongoing rise in the prevalence of elevated BP in children and adolescents is considered to be accompanied with the epidemic of childhood obesity and overweight prevalence. These findings emphasize the importance of overweight and obesity prevention in order to prevent future-related problems such as hypertension in children and adolescents. This study was supported by the medical and health program of Shandong Province, China (2009-HZ049). We would like to thank all the team members and all participants.
References
http://dx.doi.org/10.1016/j.ijcard.2014.04.010 0167-5273/© 2014 Elsevier Ireland Ltd. All rights reserved.
[1] Ezzati M, Vander Hoorn S, Lawes CM, et al. Rethinking the “diseases of affluence” paradigm: global patterns of nutritional risks in relation to economic development. PLoS Med 2005;2:404–12. [2] Bao W, Threefoot SA, Srinivasan SR, Berenson GS. Essential hypertension predicted by tracking of elevated blood pressure from childhood to adulthood: the Bogalusa Heart Study. Am J Hypertens 1995;8:657–65. [3] Vos LE, Oren A, Bots ML, Gorissen WH, Grobbee DE, Uiterwaal CS. Does a routinely measured blood pressure in young adolescence accurately predict hypertension and total cardiovascular risk in young adulthood? J Hypertens 2003;21:2027–34. [4] Chen X, Wang Y. Tracking of blood pressure from childhood to adulthood: a systematic review and meta-regression analysis. Circulation 2008;117:3171–80. [5] Klumbiene J, Sileikiene L, Milasauskiene Z, Zaborskis A, Shatchkute A. The relationship of childhood to adult blood pressure: longitudinal study of juvenile hypertension in Lithuania. J Hypertens 2000;18:531–8. [6] Muntner P, He J, Cutler JA, Wildman RP, Whelton PK. Trends in blood pressure among children and adolescents. JAMA 2004;91:2107–13. [7] Nguyen M, Mitsnefes M. Evaluation of hypertension by the general pediatrician. Curr Opin Pediatr 2007;19:165–9. [8] Cheng TO. China's epidemic of child obesity: an ounce of prevention is better than a pound of treatment. Int J Cardiol 2014;172:1–7. [9] Ji CY, Chen TJ, WGOC. Empirical changes in the prevalence of overweight and obesity among Chinese students from 1985 to 2010 and corresponding preventive strategies. Biomed Environ Sci 2013;26:1–12. [10] Ji CY, Working Group on Obesity in China (WGOC). Body mass index reference for screening overweight and obesity in Chinese school-age children. Biomed Environ Sci 2005;18:390–400. [11] Mi J, Wang TY, Meng LH, et al. Development of blood pressure reference standards for Chinese children and adolescents. Chin J Evid Based Pediatr 2010;15:4–14 [in Chinese]. [12] Bi ZQ, Wang LH, Zong L, Xu AQ. Salt intake hypertension prevalence and economic burden of Shandong population. Jinan: Shandong Science and Technology Press; 2013p. 21–30 [in Chinese].
Letters to the Editor
Synchronous prevalence of obesity and elevated blood pressure among children and adolescents in Shandong, China Ying-xiu Zhang ⁎, Jing-yang Zhou, Jin-shan Zhao 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 11 March 2014 Accepted 2 April 2014 Available online 13 April 2014 Keywords: Overweight Obesity Elevated blood pressure Prevalence Adolescent
The worldwide prevalence of hypertension in adults has become a major public health problem, since it is the main risk factor for cardiovascular disease (CVD), accounting for nearly 45% of global CVD morbidity and mortality [1]. Importantly, several epidemiological studies have provided ample evidence that hypertension in adults has its onset in childhood; children with elevated blood pressure (BP) are more likely to become hypertensive adults [2–5]. Therefore, elevated BP in childhood was a predictor of hypertension in adulthood and contributes to the current epidemic of CVD. Unfortunately, the prevalence of high BP in the pediatric population is rising, and the increase is believed to be related to the epidemic of childhood obesity [6,7]. Based on these observations, early detection and intervention in children with elevated BP is an important action for the control and prevention of hypertension in adulthood. China is the largest developing country in the world, and has now joined the world epidemic of obesity with its rapid economic growth and urbanization [8]. In 2010, it was estimated that 9.9% and 5.1% of Chinese school-aged children and adolescents were overweight and obese, representing an estimated 30.43 million individuals [9]. In this article, we report the prevalence of obesity and elevated BP among children and adolescents in Shandong, China. Data for this study were obtained from a cross-sectional survey of schoolchildren which was carried out in October 2012. A total of 15,966 students (7959 boys and 8007 girls) from 7 districts in Shandong Province, students of Han nationality, aged 7–17 years, participated in this study. All subjects voluntarily joined this study with informed
consents. The sampling method was stratified multistage sampling based on selected primary and secondary schools. Six public schools (two primary schools, two junior high schools, and two senior high schools) from each of the 7 districts in Shandong were randomly selected and invited to participate in the study. From the selected schools, two classes in each grade were selected, and all students of the selected classes were invited to join the study. All measurements were conducted by a team of trained technicians in each of the 7 districts. All measurements were taken using the same type of apparatus and followed the same procedures. Height without shoes was measured using metal column height-measuring stands to the nearest 0.1 cm. Weight was measured using lever scales to the nearest 0.1 kg while the subjects wore their underwear only. Systolic blood pressure (SBP) and diastolic blood pressure (DBP) were measured using a mercury sphygmomanometer after each subject had rested for at least 15 min in a sitting position. BP was measured twice on the right arm with an appropriately sized cuff and the average value was recorded on the study form. DBP was defined via Korotkoff Sound 5. Body mass index (BMI) was calculated from their height and weight (kg/m2). The age- and gender-specific BMI cutoff points recommended by the Working Group on Obesity in China were used to define overweight and obesity [10]. Relatively high BP status was defined as SBP and/or DBP ≥ 95th percentile for age and gender [11]. The prevalence of overweight, obesity and relatively high BP among children and adolescents in the sample are shown in Table 1. The overall prevalence of overweight, obesity and relatively high BP were 15.28%, 12.88% and 19.55% for boys, and 10.28%, 6.53% and 15.85% for girls; χ2 tests indicated that all the figures of boys were significantly higher than girls (P b 0.01). For both boys and girls, adolescents (aged 13–17 years) had higher prevalence of relatively high BP and lower prevalence of combined overweight and obesity than children (aged 7–12 years) (P b 0.01). Significant regional differences in the prevalence of overweight, obesity and relatively high BP were observed. For boys, the prevalence of relatively high BP and combined overweight and obesity varied from 24.77% and 35.88% in Jinan to 11.55% and 18.18% in Weifang, and for girls, from 21.38% and 21.75% in Jinan to 10.42% and 11.89% in Linyi. More interestingly, we found that the prevalence of relatively high BP increased with the combined overweight and obesity in the seven
Table 1 Prevalence of overweight, obesity and relatively high BP among children and adolescents aged 7–17 years, (%). Gender Boys
Girls
Age/years 7–17 7–12 13–17 7–17 7–12 13–17
n
Ov (95% CI)
Ob (95% CI)
Ov + Ob (95% CI)
RHBP (95% CI)
7959 4436 3523 8007 4454 3553
15.28 (14.49–16.07)⁎ 16.59 (15.50–17.68)⁎ 13.62 (12.49–14.75)⁎,⁎⁎ 10.28 (9.61–10.95) 9.97 (9.09–10.85) 10.67 (9.65–11.69)
12.88 (12.14–13.62)⁎ 16.48 (15.39–17.57)⁎ 8.35 (7.44–9.26)⁎,⁎⁎
28.16 (27.17–29.15)⁎ 33.07 (31.69–34.45)⁎ 21.97 (20.60–23.34)⁎,⁎⁎
19.55 13.64 26.99 15.85 13.36 18.97
Ov, overweight. Ob, obesity. RHBP, relatively high blood pressure. ⁎ P b 0.01 for gender difference. ⁎⁎ P b 0.01 compared with 7–12 year old group.
⁎ 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).
6.53 (5.99–7.07) 8.94 (8.10–9.78) 3.52 (2.91–4.13)⁎⁎
16.81 (15.99–17.63) 18.90 (17.75–20.05) 14.19 (13.04–15.34)⁎⁎
(18.68–20.42)⁎ (12.63–14.65) (25.52–28.46)⁎,⁎⁎ (15.05–16.65) (12.36–14.36) (17.68–20.26)⁎⁎
Letters to the Editor
463
Fig. 1. Prevalence of relatively high BP and combined overweight and obesity among boys aged 7–17 years in seven districts.
Fig. 2. Prevalence of relatively high BP and combined overweight and obesity among girls aged 7–17 years in seven districts.
districts. The correlation coefficient were 0.988 for boys and 0.974 for girls (P b 0.01). The synchronous prevalent trends are shown in Figs. 1 and 2. The higher prevalence of relatively high BP in Shandong children and adolescents may be related to the physical characteristics and dietary customs of Shandongese. For example, within China, children and adolescents in Shandong had higher BMI and BP levels. A survey carried out in 2011 shown that per capita daily intake of salt was 12.5 g in the Shandong population, 2-times greater than the recommended nutrient intake [12]. Two limitations are noted. First, BP measurement at a single visit usually overestimates hypertension prevalence; however, the purpose of using BP categories in the analysis was to obtain a general idea of the extent of elevated BP in the studied adolescents rather than to diagnose the presence of hypertension among them. Thus, in this paper, we use the term ‘relative high BP’ rather than ‘high BP’. Second, the absence of detailed information concerning living environments, nutritional status, dietary pattern, and physical activity at the individual level also limited our study. The present study further highlights that there is prevalence of childhood overweight/obesity and elevated BP in Shandong Province, one of the populous provinces in China. The ongoing rise in the prevalence of elevated BP in children and adolescents is considered to be accompanied with the epidemic of childhood obesity and overweight prevalence. These findings emphasize the importance of overweight and obesity prevention in order to prevent future-related problems such as hypertension in children and adolescents. This study was supported by the medical and health program of Shandong Province, China (2009-HZ049). We would like to thank all the team members and all participants.
References
http://dx.doi.org/10.1016/j.ijcard.2014.04.010 0167-5273/© 2014 Elsevier Ireland Ltd. All rights reserved.
[1] Ezzati M, Vander Hoorn S, Lawes CM, et al. Rethinking the “diseases of affluence” paradigm: global patterns of nutritional risks in relation to economic development. PLoS Med 2005;2:404–12. [2] Bao W, Threefoot SA, Srinivasan SR, Berenson GS. Essential hypertension predicted by tracking of elevated blood pressure from childhood to adulthood: the Bogalusa Heart Study. Am J Hypertens 1995;8:657–65. [3] Vos LE, Oren A, Bots ML, Gorissen WH, Grobbee DE, Uiterwaal CS. Does a routinely measured blood pressure in young adolescence accurately predict hypertension and total cardiovascular risk in young adulthood? J Hypertens 2003;21:2027–34. [4] Chen X, Wang Y. Tracking of blood pressure from childhood to adulthood: a systematic review and meta-regression analysis. Circulation 2008;117:3171–80. [5] Klumbiene J, Sileikiene L, Milasauskiene Z, Zaborskis A, Shatchkute A. The relationship of childhood to adult blood pressure: longitudinal study of juvenile hypertension in Lithuania. J Hypertens 2000;18:531–8. [6] Muntner P, He J, Cutler JA, Wildman RP, Whelton PK. Trends in blood pressure among children and adolescents. JAMA 2004;91:2107–13. [7] Nguyen M, Mitsnefes M. Evaluation of hypertension by the general pediatrician. Curr Opin Pediatr 2007;19:165–9. [8] Cheng TO. China's epidemic of child obesity: an ounce of prevention is better than a pound of treatment. Int J Cardiol 2014;172:1–7. [9] Ji CY, Chen TJ, WGOC. Empirical changes in the prevalence of overweight and obesity among Chinese students from 1985 to 2010 and corresponding preventive strategies. Biomed Environ Sci 2013;26:1–12. [10] Ji CY, Working Group on Obesity in China (WGOC). Body mass index reference for screening overweight and obesity in Chinese school-age children. Biomed Environ Sci 2005;18:390–400. [11] Mi J, Wang TY, Meng LH, et al. Development of blood pressure reference standards for Chinese children and adolescents. Chin J Evid Based Pediatr 2010;15:4–14 [in Chinese]. [12] Bi ZQ, Wang LH, Zong L, Xu AQ. Salt intake hypertension prevalence and economic burden of Shandong population. Jinan: Shandong Science and Technology Press; 2013p. 21–30 [in Chinese].
