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The association between components of height and blood pressure among children and adolescents in Shandong, China
International Journal of Cardiology 182 (2015) 18–19
Contents lists available at ScienceDirect
International Journal of Cardiology journal homepage: www.elsevier.com/locate/ijcard
Letter to the Editor
The association between components of height and blood pressure among children and adolescents in Shandong, China Ying-xiu Zhang ⁎, Jin-shan Zhao, Zun-hua Chu, Lian-sen Wang 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 29 December 2014 Accepted 2 January 2015 Available online 5 January 2015 Keywords: Sitting height Leg length Sitting height to height ratio Blood pressure Child and adolescent
A few studies have divided height into its components: trunk (upper body) and leg (lower body) length. In practice, sitting height (SH) used to represent trunk length. Thus, SH, leg length (LL) and SH to height ratio (SH/H), are useful indicators in assessing body proportion; a larger SH/H indicates relatively shorter legs for total stature. The associations of body proportion with some diseases have been examined. A few studies in adults have linked shorter leg length and a lower leg-totrunk length ratio with a higher prevalence of coronary heart disease and type 2 diabetes [1–3]. Gunnell et al. also reported that some cancers, such as prostate and testicular cancer, premenopausal breast cancer, endometrial cancer and colorectal cancer, are associated with relatively longer legs [4]. It is well known that blood pressure (BP) is closely associated with body size, with greater height is correlated with higher BP in children and adolescents [5–7]. However, the associations of two components of height (SH and LL) with BP in childhood have seldom been studied. More recently, Montagnese et al. reported that BP levels were positively associated with SH and inversely associated with LL in an Italian adult population [8]. Regnault et al. reported a positive correlation between SH and BP in childhood [9]. In this article, we report the association between components of height and BP levels in a large sample in Shandong children and adolescents. ⁎ 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.2015.01.008 0167-5273/© 2014 Elsevier Ireland Ltd. All rights reserved.
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 and sitting height (SH) were measured using metal column height/sitting height measuring stands (Yilian, TZG; Shanghai Yilian Science & Education Equipment Company, Limited) to the nearest 0.1 cm. Leg length (LL) was calculated as height minus SH. SH to height ratio (SH/H) was calculated as SH divided by total height. 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, SH and LL were calculated from the national reference values [10]. The age- and sex-specific quartiles of SH/H were calculated, those in the upper fourth (N 75th) were defined as ‘high SH/H’, and those in the lower fourth (b25th) were defined as ‘low SH/H’. Comparisons of Z-scores for SBP and DBP between the two groups were made by t-test. SBP and DBP Z-scores were positively correlated with height, SH and LL Z-scores in both boys and girls (P b 0.01). The correlation coefficients of SBP Z-scores with height, SH and LL Z-scores were 0.206, 0.220 and 0.073 for boys and 0.137, 0.157 and 0.047 for girls, respectively; the corresponding coefficients of DBP were 0.145, 0.132 and 0.079 for boys and 0.109, 0.097 and 0.059 for girls, respectively. The correlation coefficients of BP with SH were higher than with LL, indicating that the associations of BP with upper body length were stronger than with lower body length. Fig. 1 shows the Z-scores of BP increased with SH percentiles in both boys and girls. The Z-scores of SBP and DBP from −0.08 ± 1.07, 0.12 ± 0.97 for boys and 0.09 ± 1.10, 0.13 ± 1.08 for girls in the b5th SH percentile group to 0.94 ± 1.09, 0.72 ± 0.97 for boys and 0.82 ± 1.09, 0.65 ± 0.99 for girls in the ≥ 95th SH percentile group, respectively; the graded increase trend is very obvious. The comparisons of Z-score of SBP and DBP between low SH/H and high SH/H groups are presented in Table 1. In both boys and girls, statistical significant differences in SBP and DBP were observed between the two groups (P b 0.01), indicating that children and adolescents with
Y. Zhang et al. / International Journal of Cardiology 182 (2015) 18–19
19
Table 1 Comparisons of Z-score of SBP and DBP between low SH/H and high SH/H groups in boys and girls aged 7–18 years. Gender
SH/H b25th n
Boys Girls
5281 5226
ZSBP 0.35 ± 1.08 0.31 ± 1.07
SH/H N75th ZDBP 0.37 ± 0.96 0.34 ± 0.98
n
ZSBP
ZDBP
5330 5293
0.55 ± 1.07⁎ 0.49 ± 1.09⁎
0.48 ± 0.99⁎ 0.42 ± 1.01⁎
Data of ZSBP and ZDBP presented as mean ± SD. ⁎ P b 0.01, t-test.
Conflict of interest There are no conflicts of interest on behalf of any of the authors. Acknowledgments 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. Special thanks to Mr. B Yu for providing access to the survey data. References
Fig. 1. The Z-scores of SBP (a) and DBP (b) within each sitting height percentile category in boys and girls.
high SH/H (N75th) had higher BP levels than their low SH/H (b 25th) peers. Children and adolescents aged 7–18 years in the high SH/H group had higher SBP and DBP than those in the low SH/H group in all age groups, the range of differences being 2.4–4.1 mm Hg, 2.0–3.1 mm Hg for boys, and 2.3–3.8 mm Hg, 2.1–2.8 mm Hg for girls. Based on a large sample, the association between components of height and BP levels in children and adolescents was examined for the first time in Shandong, China. The correlation of BP with SH is stronger than with LL, children and adolescents with greater SH and SH/H had higher BP levels. Our results support the findings from the US that children with greater trunk lengths had higher BP levels, perhaps because of the additional pressure needed to overcome gravity to perfuse the brain [9]. Two limitations are noted. First, the absence of detailed information concerning nutritional status, dietary patterns and physical activity at the individual level limited our study. Second, we did not include body composition, body fat distribution and puberty measures, and these can potentially influence the BP.
[1] K. Asao, W.H. Kao, K. Baptiste-Roberts, K. Bandeen-Roche, T.P. Erlinger, F.L. Brancati, Short stature and the risk of adiposity, insulin resistance, and type 2 diabetes in middle age: the Third National Health and Nutrition Examination Survey (NHANES III), 1988–1994, Diabetes Care 29 (2006) 1632–1637. [2] D. Lawlor, S. Ebrahim, Smith G. Davey, The association between components of adult height and type II diabetes and insulin resistance: British Women's Heart and Health Study, Diabetologia 45 (2002) 1096–1106. [3] G.D. Smith, R. Greenwood, D. Gunnell, P. Sweetnam, J. Yarnell, P. Elwood, Leg length, insulin resistance, and coronary heart disease risk: the Caerphilly study, J. Epidemiol. Community Health 55 (2001) 867–872. [4] D. Gunnell, M. Okasha, G.D. Smith, S.E. Oliver, J. Sandhu, J.M. Holly, Height, leg length, and cancer risk: a systematic review, Epidemiol. Rev. 23 (2001) 313–342. [5] The fourth report on the diagnosis, evaluation, and treatment of high blood pressure in children and adolescentsNational High Blood Pressure Education Program Working Group on high blood pressure in children and adolescents Pediatrics 114 (2004) 555–576. [6] 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. [7] J. Ma, Z. Wang, B. Dong, Y. Song, P. Hu, B. Zhang, Quantifying the relationships of blood pressure with weight, height and body mass index in Chinese children and adolescents, J. Paediatr. Child Health 48 (2012) 413–418. [8] C. Montagnese, T. Nutile, A.A. Marphatia, C.S. Grijalva-Eternod, M. Siervo, M. Ciullo, J.C. Wells, Body composition, leg length and blood pressure in a rural Italian population: a test of the capacity-load model, Nutr. Metab. Cardiovasc. Dis. 24 (2014) 1204–1212. [9] N. Regnault, K.P. Kleinman, S.L. Rifas-Shiman, C. Langenberg, S.E. Lipshultz, M.W. Gillman, Components of height and blood pressure in childhood, Int. J. Epidemiol. 43 (2014) 149–159. [10] 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, pp. 81–98 (in Chinese).
Contents lists available at ScienceDirect
International Journal of Cardiology journal homepage: www.elsevier.com/locate/ijcard
Letter to the Editor
The association between components of height and blood pressure among children and adolescents in Shandong, China Ying-xiu Zhang ⁎, Jin-shan Zhao, Zun-hua Chu, Lian-sen Wang 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 29 December 2014 Accepted 2 January 2015 Available online 5 January 2015 Keywords: Sitting height Leg length Sitting height to height ratio Blood pressure Child and adolescent
A few studies have divided height into its components: trunk (upper body) and leg (lower body) length. In practice, sitting height (SH) used to represent trunk length. Thus, SH, leg length (LL) and SH to height ratio (SH/H), are useful indicators in assessing body proportion; a larger SH/H indicates relatively shorter legs for total stature. The associations of body proportion with some diseases have been examined. A few studies in adults have linked shorter leg length and a lower leg-totrunk length ratio with a higher prevalence of coronary heart disease and type 2 diabetes [1–3]. Gunnell et al. also reported that some cancers, such as prostate and testicular cancer, premenopausal breast cancer, endometrial cancer and colorectal cancer, are associated with relatively longer legs [4]. It is well known that blood pressure (BP) is closely associated with body size, with greater height is correlated with higher BP in children and adolescents [5–7]. However, the associations of two components of height (SH and LL) with BP in childhood have seldom been studied. More recently, Montagnese et al. reported that BP levels were positively associated with SH and inversely associated with LL in an Italian adult population [8]. Regnault et al. reported a positive correlation between SH and BP in childhood [9]. In this article, we report the association between components of height and BP levels in a large sample in Shandong children and adolescents. ⁎ 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.2015.01.008 0167-5273/© 2014 Elsevier Ireland Ltd. All rights reserved.
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 and sitting height (SH) were measured using metal column height/sitting height measuring stands (Yilian, TZG; Shanghai Yilian Science & Education Equipment Company, Limited) to the nearest 0.1 cm. Leg length (LL) was calculated as height minus SH. SH to height ratio (SH/H) was calculated as SH divided by total height. 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, SH and LL were calculated from the national reference values [10]. The age- and sex-specific quartiles of SH/H were calculated, those in the upper fourth (N 75th) were defined as ‘high SH/H’, and those in the lower fourth (b25th) were defined as ‘low SH/H’. Comparisons of Z-scores for SBP and DBP between the two groups were made by t-test. SBP and DBP Z-scores were positively correlated with height, SH and LL Z-scores in both boys and girls (P b 0.01). The correlation coefficients of SBP Z-scores with height, SH and LL Z-scores were 0.206, 0.220 and 0.073 for boys and 0.137, 0.157 and 0.047 for girls, respectively; the corresponding coefficients of DBP were 0.145, 0.132 and 0.079 for boys and 0.109, 0.097 and 0.059 for girls, respectively. The correlation coefficients of BP with SH were higher than with LL, indicating that the associations of BP with upper body length were stronger than with lower body length. Fig. 1 shows the Z-scores of BP increased with SH percentiles in both boys and girls. The Z-scores of SBP and DBP from −0.08 ± 1.07, 0.12 ± 0.97 for boys and 0.09 ± 1.10, 0.13 ± 1.08 for girls in the b5th SH percentile group to 0.94 ± 1.09, 0.72 ± 0.97 for boys and 0.82 ± 1.09, 0.65 ± 0.99 for girls in the ≥ 95th SH percentile group, respectively; the graded increase trend is very obvious. The comparisons of Z-score of SBP and DBP between low SH/H and high SH/H groups are presented in Table 1. In both boys and girls, statistical significant differences in SBP and DBP were observed between the two groups (P b 0.01), indicating that children and adolescents with
Y. Zhang et al. / International Journal of Cardiology 182 (2015) 18–19
19
Table 1 Comparisons of Z-score of SBP and DBP between low SH/H and high SH/H groups in boys and girls aged 7–18 years. Gender
SH/H b25th n
Boys Girls
5281 5226
ZSBP 0.35 ± 1.08 0.31 ± 1.07
SH/H N75th ZDBP 0.37 ± 0.96 0.34 ± 0.98
n
ZSBP
ZDBP
5330 5293
0.55 ± 1.07⁎ 0.49 ± 1.09⁎
0.48 ± 0.99⁎ 0.42 ± 1.01⁎
Data of ZSBP and ZDBP presented as mean ± SD. ⁎ P b 0.01, t-test.
Conflict of interest There are no conflicts of interest on behalf of any of the authors. Acknowledgments 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. Special thanks to Mr. B Yu for providing access to the survey data. References
Fig. 1. The Z-scores of SBP (a) and DBP (b) within each sitting height percentile category in boys and girls.
high SH/H (N75th) had higher BP levels than their low SH/H (b 25th) peers. Children and adolescents aged 7–18 years in the high SH/H group had higher SBP and DBP than those in the low SH/H group in all age groups, the range of differences being 2.4–4.1 mm Hg, 2.0–3.1 mm Hg for boys, and 2.3–3.8 mm Hg, 2.1–2.8 mm Hg for girls. Based on a large sample, the association between components of height and BP levels in children and adolescents was examined for the first time in Shandong, China. The correlation of BP with SH is stronger than with LL, children and adolescents with greater SH and SH/H had higher BP levels. Our results support the findings from the US that children with greater trunk lengths had higher BP levels, perhaps because of the additional pressure needed to overcome gravity to perfuse the brain [9]. Two limitations are noted. First, the absence of detailed information concerning nutritional status, dietary patterns and physical activity at the individual level limited our study. Second, we did not include body composition, body fat distribution and puberty measures, and these can potentially influence the BP.
[1] K. Asao, W.H. Kao, K. Baptiste-Roberts, K. Bandeen-Roche, T.P. Erlinger, F.L. Brancati, Short stature and the risk of adiposity, insulin resistance, and type 2 diabetes in middle age: the Third National Health and Nutrition Examination Survey (NHANES III), 1988–1994, Diabetes Care 29 (2006) 1632–1637. [2] D. Lawlor, S. Ebrahim, Smith G. Davey, The association between components of adult height and type II diabetes and insulin resistance: British Women's Heart and Health Study, Diabetologia 45 (2002) 1096–1106. [3] G.D. Smith, R. Greenwood, D. Gunnell, P. Sweetnam, J. Yarnell, P. Elwood, Leg length, insulin resistance, and coronary heart disease risk: the Caerphilly study, J. Epidemiol. Community Health 55 (2001) 867–872. [4] D. Gunnell, M. Okasha, G.D. Smith, S.E. Oliver, J. Sandhu, J.M. Holly, Height, leg length, and cancer risk: a systematic review, Epidemiol. Rev. 23 (2001) 313–342. [5] The fourth report on the diagnosis, evaluation, and treatment of high blood pressure in children and adolescentsNational High Blood Pressure Education Program Working Group on high blood pressure in children and adolescents Pediatrics 114 (2004) 555–576. [6] 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. [7] J. Ma, Z. Wang, B. Dong, Y. Song, P. Hu, B. Zhang, Quantifying the relationships of blood pressure with weight, height and body mass index in Chinese children and adolescents, J. Paediatr. Child Health 48 (2012) 413–418. [8] C. Montagnese, T. Nutile, A.A. Marphatia, C.S. Grijalva-Eternod, M. Siervo, M. Ciullo, J.C. Wells, Body composition, leg length and blood pressure in a rural Italian population: a test of the capacity-load model, Nutr. Metab. Cardiovasc. Dis. 24 (2014) 1204–1212. [9] N. Regnault, K.P. Kleinman, S.L. Rifas-Shiman, C. Langenberg, S.E. Lipshultz, M.W. Gillman, Components of height and blood pressure in childhood, Int. J. Epidemiol. 43 (2014) 149–159. [10] 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, pp. 81–98 (in Chinese).