International Journal of Cardiology 182 (2015) 52–53
Contents lists available at ScienceDirect
International Journal of Cardiology journal homepage: www.elsevier.com/locate/ijcard
Letter to the Editor
Body size and high intake of salt is associated with elevated blood pressure among children and adolescents in Shandong, China Ying-xiu Zhang a,⁎, Min Chen b, Juan Zhou b, Jing-yang Zhou a a b
Shandong Center for Disease Control and Prevention, Shandong University Institute of Preventive Medicine, Shandong, China Shandong Blood Center, Shandong, China
a r t i c l e
i n f o
Article history: Received 9 December 2014 Accepted 29 December 2014 Available online 30 December 2014 Keywords: Blood pressure Body size Intake of salt Child and adolescent
The rising prevalence of hypertension in adults has been observed in China [1]. 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 km2 (about 60,500 miles2) and a total population of 95.79 million in 2010. More importantly, Shandong Province is one of the areas of China with higher prevalence of hypertension; based on data of the China Health and Nutrition Survey (CHNS) conducted in 2002, prevalence of hypertension among adults in Shandong had reached 29.22% (31.52% for males, 27.33% for females) [2]. Several 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 [3,4]. Unfortunately, we found that Shandong children and adolescents had a higher BP level than the national reference values. Data for this study were obtained from a large cross-sectional survey of schoolchildren. A total of 42,334 students (21,244 boys and 21,090 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. All measurements were performed by well-trained health professionals in each of the 16 districts 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 ⁎ Corresponding author at: Shandong Center for Disease Control and Prevention, Shandong University Institute of Preventive Medicine, 16992 Jingshi Road, Jinan, Shandong 250014, China. E-mail address: [email protected] (Y. Zhang).
http://dx.doi.org/10.1016/j.ijcard.2014.12.134 0167-5273/© 2014 Elsevier Ireland Ltd. All rights reserved.
0.1 cm. Weight was measured using lever scales to the nearest 0.1 kg while the subjects wore their underwear only. Body mass index (BMI) was calculated from their height and weight (kg/m2). 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. Skinfold thicknesses (SFT) were measured on the right side of the body using Skinfold Caliper (GMCS-PZQ; Beijing Xindong Huateng Sports Instruments Company, Limited) 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 the 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 was analyzed. 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. Z-scores of SBP, DBP, height, weight, WC, BMI and SFT were calculated from the national reference values [5]. We found that the Z-scores of SBP and DBP of Shandong children and adolescents were above zero (0.45 and 0.40 for boys, and 0.40 and 0.39 for girls), indicating that the BP level of children and adolescents in this region was above the national reference values (P b 0.01, Table 1). Shandong children and adolescents aged 7–18 years had higher SBP and DBP levels than the national reference values in all age groups, the range of differences being 3.7–6.9 mm Hg, 3.1–5.3 mm Hg for boys, and 3.8–5.4 mm Hg, 2.9–4.9 mm Hg for girls, respectively (Fig. 1). It may relate to the physical characteristics and dietary customs of Shandongese. First, it has been reported that BP level is closely associated with body size (e.g. height, weight and BMI) in children and adolescents [6, 7]. Shandongese has long been known as ‘Shandong burly fellow’. In this study, for example, we found that the mean values of height, weight, WC, BMI and SFT of Shandong children and adolescents were all significantly higher than the national reference values (P b 0.01). Shandong children and adolescents aged 7–18 years had higher height, weight, WC, BMI and SFT than the national reference values in all age groups, the range of differences being 2.6–4.3 cm, 2.7–5.2 kg, 1.5–3.1 cm, 0.7–1.1 kg/m2 and 3.8–6.7 mm for boys, and 2.2–3.4 cm,
Y. Zhang et al. / International Journal of Cardiology 182 (2015) 52–53
53
Table 1 Z-scores of physical indicators of children and adolescents aged 7–18 years in Shandong (mean ± SD). Gender
n
SBP
DBP
Height
Weight
BMI
WC
SFT
Boys Girls
21,244 21,090
0.45 ± 1.07⁎ 0.40 ± 1.06⁎
0.40 ± 0.98⁎ 0.39 ± 1.01⁎
0.44 ± 0.97⁎ 0.43 ± 0.98⁎
0.44 ± 1.12⁎ 0.40 ± 1.08⁎
0.31 ± 1.14⁎ 0.25 ± 1.12⁎
0.47 ± 1.01⁎ 0.38 ± 0.99⁎
0.25 ± 1.11⁎ 0.22 ± 1.08⁎
⁎ P b 0.01 compared with the national reference values. SFT, the sum of triceps, subscapular and abdomen skinfold thickness.
130 120
a
110 Shandong SBP
mmHg
100
Shandong DBP
90
Chinese SBP Chinese DBP
80 70 60 50
7
8
9
10
11
12
13
14
15
16
17
18
Age/years
Conflict of interest
130 120
There are no conflicts of interest on behalf of any of the authors.
b
References
mmHg
110 100
Shandong SBP
90
Shandong DBP Chinese SBP
80
Chinese DBP
70 60 50
hypertension has been carried out by the government in Shandong, China, and the effect needs further study. In summary, Shandong Province is one of the areas of China with higher prevalence of hypertension. Children and adolescents in this region had higher BP level, which is associated with the larger body size and high intake of salt. Considering the tracking phenomenon of BP, children and adolescents with elevated BP are more likely to become hypertensive adults, the prevention of hypertension in this region facing a serious situation and challenges. This study was supported by the Medical and Health Program of Shandong, China (2014WS0376). 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.
7
8
9
10
11
12
13
14
15
16
17
18
Age/years Fig. 1. The mean values of SBP and DBP of Shandong and Chinese boys (a) and girls (b) in 2010.
2.4–3.6 kg, 1.2–2.0 cm, 0.5–1.0 kg/m2 and 3.3–5.4 mm for girls, respectively. Secondly, high dietary intake of salt has been identified as an important risk factor for hypertension [8,9]. However, a prominent eating habit of Shandongese is fond of salty food, this is a traditional habit and hard to change in the short term. A survey carried out in 2011 showed that per capita daily intake of salt was 12.5 g in the Shandong population, which is 2 times greater than the recommended nutrient intake [10]. Fortunately, a project of reduced dietary salt for the prevention of
[1] B. Xi, Y.J. Liang, K.H. Reilly, Q.J. Wang, Y.H. Hu, W.H. Tang, Trends in prevalence, awareness, treatment, and control of hypertension among Chinese adults 1991–2009, Int. J. Cardiol. 158 (2012) 326–329. [2] J.Y. Zhou, J.L. Zhang, Dietary Nutrition and Health Status of Shandong Population, Shandong Electronic Audio & Video Publishing House, Jinan, 2008. 17–18 (in Chinese). [3] X. Chen, Y. Wang, Tracking of blood pressure from childhood to adulthood: a systematic review and meta-regression analysis, Circulation 117 (2008) 3171–3180. [4] J. Klumbiene, L. Sileikiene, Z. Milasauskiene, A. Zaborskis, A. Shatchkute, The relationship of childhood to adult blood pressure: longitudinal study of juvenile hypertension in Lithuania, J. Hypertens. 18 (2000) 531–538. [5] Research Section of the Constitution and Health of Chinese Students (RSCHCS), Report on the Physical Fitness and Health Research of Chinese School Students, Higher Education Press, Beijing, 2012. 81–98 (in Chinese). [6] National High Blood Pressure Education Program Working Group on High Blood Pressure in Children and Adolescents, The fourth report on the diagnosis, evaluation, and treatment of high blood pressure in children and adolescents, Pediatrics 114 (2004) 555–576. [7] M. LA de Hoog, M. van Eijsden, K. Stronks, R.J. Gemke, T.G. Vrijkotte, Association between body size and blood pressure in children from different ethnic origins, Cardiovasc. Diabetol. 11 (2012) 136–145. [8] Y. Erdem, M. Arici, B. Altun, C. Turgan, S. Sindel, B. Erbay, U. Derici, O. Karatan, E. Hasanoglu, S. Caglar, The relationship between hypertension and salt intake in Turkish population: SALTURK study, Blood Press. 19 (2010) 313–318. [9] F.J. He, G.A. MacGregor, A comprehensive review on salt and health and current experience of worldwide salt reduction programmes, J. Hum. Hypertens. 23 (2009) 363–384. [10] Z.Q. Bi, L.H. Wang, L. Zong, A.Q. Xu, Salt Intake Hypertension Prevalence and Economic Burden of Shandong Population, Shandong Science and Technology Press, Jinan, 2013. 21–30 (in Chinese).
Contents lists available at ScienceDirect
International Journal of Cardiology journal homepage: www.elsevier.com/locate/ijcard
Letter to the Editor
Body size and high intake of salt is associated with elevated blood pressure among children and adolescents in Shandong, China Ying-xiu Zhang a,⁎, Min Chen b, Juan Zhou b, Jing-yang Zhou a a b
Shandong Center for Disease Control and Prevention, Shandong University Institute of Preventive Medicine, Shandong, China Shandong Blood Center, Shandong, China
a r t i c l e
i n f o
Article history: Received 9 December 2014 Accepted 29 December 2014 Available online 30 December 2014 Keywords: Blood pressure Body size Intake of salt Child and adolescent
The rising prevalence of hypertension in adults has been observed in China [1]. 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 km2 (about 60,500 miles2) and a total population of 95.79 million in 2010. More importantly, Shandong Province is one of the areas of China with higher prevalence of hypertension; based on data of the China Health and Nutrition Survey (CHNS) conducted in 2002, prevalence of hypertension among adults in Shandong had reached 29.22% (31.52% for males, 27.33% for females) [2]. Several 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 [3,4]. Unfortunately, we found that Shandong children and adolescents had a higher BP level than the national reference values. Data for this study were obtained from a large cross-sectional survey of schoolchildren. A total of 42,334 students (21,244 boys and 21,090 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. All measurements were performed by well-trained health professionals in each of the 16 districts 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 ⁎ Corresponding author at: Shandong Center for Disease Control and Prevention, Shandong University Institute of Preventive Medicine, 16992 Jingshi Road, Jinan, Shandong 250014, China. E-mail address: [email protected] (Y. Zhang).
http://dx.doi.org/10.1016/j.ijcard.2014.12.134 0167-5273/© 2014 Elsevier Ireland Ltd. All rights reserved.
0.1 cm. Weight was measured using lever scales to the nearest 0.1 kg while the subjects wore their underwear only. Body mass index (BMI) was calculated from their height and weight (kg/m2). 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. Skinfold thicknesses (SFT) were measured on the right side of the body using Skinfold Caliper (GMCS-PZQ; Beijing Xindong Huateng Sports Instruments Company, Limited) 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 the 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 was analyzed. 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. Z-scores of SBP, DBP, height, weight, WC, BMI and SFT were calculated from the national reference values [5]. We found that the Z-scores of SBP and DBP of Shandong children and adolescents were above zero (0.45 and 0.40 for boys, and 0.40 and 0.39 for girls), indicating that the BP level of children and adolescents in this region was above the national reference values (P b 0.01, Table 1). Shandong children and adolescents aged 7–18 years had higher SBP and DBP levels than the national reference values in all age groups, the range of differences being 3.7–6.9 mm Hg, 3.1–5.3 mm Hg for boys, and 3.8–5.4 mm Hg, 2.9–4.9 mm Hg for girls, respectively (Fig. 1). It may relate to the physical characteristics and dietary customs of Shandongese. First, it has been reported that BP level is closely associated with body size (e.g. height, weight and BMI) in children and adolescents [6, 7]. Shandongese has long been known as ‘Shandong burly fellow’. In this study, for example, we found that the mean values of height, weight, WC, BMI and SFT of Shandong children and adolescents were all significantly higher than the national reference values (P b 0.01). Shandong children and adolescents aged 7–18 years had higher height, weight, WC, BMI and SFT than the national reference values in all age groups, the range of differences being 2.6–4.3 cm, 2.7–5.2 kg, 1.5–3.1 cm, 0.7–1.1 kg/m2 and 3.8–6.7 mm for boys, and 2.2–3.4 cm,
Y. Zhang et al. / International Journal of Cardiology 182 (2015) 52–53
53
Table 1 Z-scores of physical indicators of children and adolescents aged 7–18 years in Shandong (mean ± SD). Gender
n
SBP
DBP
Height
Weight
BMI
WC
SFT
Boys Girls
21,244 21,090
0.45 ± 1.07⁎ 0.40 ± 1.06⁎
0.40 ± 0.98⁎ 0.39 ± 1.01⁎
0.44 ± 0.97⁎ 0.43 ± 0.98⁎
0.44 ± 1.12⁎ 0.40 ± 1.08⁎
0.31 ± 1.14⁎ 0.25 ± 1.12⁎
0.47 ± 1.01⁎ 0.38 ± 0.99⁎
0.25 ± 1.11⁎ 0.22 ± 1.08⁎
⁎ P b 0.01 compared with the national reference values. SFT, the sum of triceps, subscapular and abdomen skinfold thickness.
130 120
a
110 Shandong SBP
mmHg
100
Shandong DBP
90
Chinese SBP Chinese DBP
80 70 60 50
7
8
9
10
11
12
13
14
15
16
17
18
Age/years
Conflict of interest
130 120
There are no conflicts of interest on behalf of any of the authors.
b
References
mmHg
110 100
Shandong SBP
90
Shandong DBP Chinese SBP
80
Chinese DBP
70 60 50
hypertension has been carried out by the government in Shandong, China, and the effect needs further study. In summary, Shandong Province is one of the areas of China with higher prevalence of hypertension. Children and adolescents in this region had higher BP level, which is associated with the larger body size and high intake of salt. Considering the tracking phenomenon of BP, children and adolescents with elevated BP are more likely to become hypertensive adults, the prevention of hypertension in this region facing a serious situation and challenges. This study was supported by the Medical and Health Program of Shandong, China (2014WS0376). 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.
7
8
9
10
11
12
13
14
15
16
17
18
Age/years Fig. 1. The mean values of SBP and DBP of Shandong and Chinese boys (a) and girls (b) in 2010.
2.4–3.6 kg, 1.2–2.0 cm, 0.5–1.0 kg/m2 and 3.3–5.4 mm for girls, respectively. Secondly, high dietary intake of salt has been identified as an important risk factor for hypertension [8,9]. However, a prominent eating habit of Shandongese is fond of salty food, this is a traditional habit and hard to change in the short term. A survey carried out in 2011 showed that per capita daily intake of salt was 12.5 g in the Shandong population, which is 2 times greater than the recommended nutrient intake [10]. Fortunately, a project of reduced dietary salt for the prevention of
[1] B. Xi, Y.J. Liang, K.H. Reilly, Q.J. Wang, Y.H. Hu, W.H. Tang, Trends in prevalence, awareness, treatment, and control of hypertension among Chinese adults 1991–2009, Int. J. Cardiol. 158 (2012) 326–329. [2] J.Y. Zhou, J.L. Zhang, Dietary Nutrition and Health Status of Shandong Population, Shandong Electronic Audio & Video Publishing House, Jinan, 2008. 17–18 (in Chinese). [3] X. Chen, Y. Wang, Tracking of blood pressure from childhood to adulthood: a systematic review and meta-regression analysis, Circulation 117 (2008) 3171–3180. [4] J. Klumbiene, L. Sileikiene, Z. Milasauskiene, A. Zaborskis, A. Shatchkute, The relationship of childhood to adult blood pressure: longitudinal study of juvenile hypertension in Lithuania, J. Hypertens. 18 (2000) 531–538. [5] Research Section of the Constitution and Health of Chinese Students (RSCHCS), Report on the Physical Fitness and Health Research of Chinese School Students, Higher Education Press, Beijing, 2012. 81–98 (in Chinese). [6] National High Blood Pressure Education Program Working Group on High Blood Pressure in Children and Adolescents, The fourth report on the diagnosis, evaluation, and treatment of high blood pressure in children and adolescents, Pediatrics 114 (2004) 555–576. [7] M. LA de Hoog, M. van Eijsden, K. Stronks, R.J. Gemke, T.G. Vrijkotte, Association between body size and blood pressure in children from different ethnic origins, Cardiovasc. Diabetol. 11 (2012) 136–145. [8] Y. Erdem, M. Arici, B. Altun, C. Turgan, S. Sindel, B. Erbay, U. Derici, O. Karatan, E. Hasanoglu, S. Caglar, The relationship between hypertension and salt intake in Turkish population: SALTURK study, Blood Press. 19 (2010) 313–318. [9] F.J. He, G.A. MacGregor, A comprehensive review on salt and health and current experience of worldwide salt reduction programmes, J. Hum. Hypertens. 23 (2009) 363–384. [10] Z.Q. Bi, L.H. Wang, L. Zong, A.Q. Xu, Salt Intake Hypertension Prevalence and Economic Burden of Shandong Population, Shandong Science and Technology Press, Jinan, 2013. 21–30 (in Chinese).
