Obesity Research & Clinical Practice (2013) 7, e284—e289
SHORT REPORT
Prevalence of elevated blood pressure and its relationship with fat mass, body mass index and waist circumference among a group of Moroccan overweight adolescents Slimane Mehdad a,∗, Abdeslam Hamrani a, Khalid El Kari a, Asmaa El Hamdouchi a, Mohammed El Mzibri a, Amina Barkat a,b, Hassan Aguenaou a, Najat Mokhtar a a
Unité Mixte de Recherche en Nutrition et Alimentation, URAC39 (Université Ibn Tofaïl Kenitra — Centre National de l’Energie, des Sciences et Techniques Nucléaires), Morocco b Equipe de Recherche en santé et nutrition du couple mère- nouveau-né, Faculté de Médecine et de Pharmacie, Rabat, Morocco Received 17 December 2011 ; received in revised form 31 January 2012; accepted 8 February 2012
KEYWORDS Adolescents; Blood pressure; Body mass index; Fat mass; Hypertension; Obesity; Overweight; Waist circumference
Summary This study aimed to estimate the prevalence of hypertension among a group of adolescents and to assess the relationship of systolic and diastolic blood pressure (SBP, DBP) with body fat mass (BFM), body mass index (BMI) and waist circumference (WC). A total of 167 subjects aged 11—17 years were recruited, 29.3% and 12.6% were overweight and obese respectively. BMI, WC, SBP and DBP were determined using standardized equipment. BFM was estimated by the deuterium oxide dilution. Hypertension (HT) and prehypertension (pre-HT) were observed in 17.4% and 9.6%, of the study population, respectively. The prevalence of HT and pre-HT was significantly higher in boys and in overweight-obese groups (p = 0.044; p = 0.003 respectively). Both SBP and DBP were significantly higher in overweight-obese compared to healthy-weight groups (p < 0.001; p = 0.002 respectively). SBP was significantly higher in boys than girls (p = 0.013). With some exceptions, SBP and DBP were
Abbreviations: BMI, body mass index; BFM, body fat mass; DBP, diastolic blood pressure; HT, hypertension; pre-HT, prehypertension; SBP, systolic blood pressure; SD, standard deviation; WC, waist circumference; WHO, World Health Organization. ∗ Corresponding author at: URAC 39, CNESTEN, BP 1382 Madinat Al Irfane, Rabat 10001, Morocco. Tel.: +212 672 210 338/537 217 635; fax: +212 537 217 670/34. E-mail addresses: [email protected] (S. Mehdad), [email protected] (A. Hamrani), [email protected] (K.E. Kari), [email protected] (A.E. Hamdouchi), [email protected] (M.E. Mzibri), [email protected] (A. Barkat), [email protected] (H. Aguenaou), [email protected] (N. Mokhtar). 1871-403X/$ — see front matter © 2012 Asian Oceanian Association for the Study of Obesity. Published by Elsevier Ltd. All rights reserved.
doi:10.1016/j.orcp.2012.02.006
Prevalence of elevated blood pressure
e285
significantly correlated with BMI, WC and BFM in the study population and different weight-status groups of both genders. The relationship of blood pressure with BMI appeared to be more significant than with WC and BFM. The prevalence of hypertension was higher in boys than girls and in overweight-obese than healthy-weight adolescents. Overall SBP and DBP were associated with BFM, BMI and WC. However, the strong association between these variables was seen in girls, and the greater risk of developing hypertension could be associated with increasing BMI. © 2012 Asian Oceanian Association for the Study of Obesity. Published by Elsevier Ltd. All rights reserved.
The increasing prevalence of obesity and overweight among adolescents has led to a surge of several chronic illnesses such as type 2 diabetes mellitus [1,2], high levels of blood pressure [3,4], adiposity-associated morbidity [5] and dyslipidemia [6,7]. Moreover obesity and the associated metabolic abnormalities generally seen in a young age have a high risk to remain into adulthood [8,9]. Thus childhood overweight and obesity are considered as critical public health problems [10]. It has been shown repeatedly that obesity measurements had strong relationship with risks of chronic diseases in adults [11,12]. Some studies indicated that overweight and obese children and adolescents have systematically higher levels of blood pressure than their healthy weight counterparts [13,14]. However, it is not yet clear whether this relationship between blood pressure and weight status can be also found in adolescents of all ethnic groups. Epidemiological studies have found a progressive increasing of elevated blood pressure prevalence with increasing adipose tissue [15] and a close relationship between increased abdominal obesity assessed by waist circumference and metabolic risk factors in adults [16,17]. Nevertheless few studies explored this association in adolescents [18,19]. The current study aimed to estimate the prevalence of hypertension among a group of adolescents from Rabat region. It also aimed to explore, for the first time to our knowledge, the relationship between blood pressure and each of body fat mass (BFM), body mass index (BMI) and waist circumference (WC), and to identify which of these obesity measures could be the best predictor of elevated blood pressure. The study protocol was approved by the relevant national authorities. Seven secondary schools randomly selected in the Rabat region (Morocco) were involved in the study. A systematic random sampling procedure was used to select the subjects who were invited to participate in the study. As
the number of overweight or obese adolescents was very low, a further stratification according to their weight status was used. Each of healthy weight and overweight/obese groups were selected separately among their peers in each school using a simple random sampling design. A total of 167 adolescents (123 girls and 44 boys) aged 11—17 years were recruited. Informed consents were obtained from their parents. Standardized equipment was used by trained operators to take anthropometric measurements. Body weight was measured to the nearest 0.1 kg using Seca Model 770 digital electronic scale with minimal clothing and without shoes. Height was measured to the nearest 0.1 cm using a height bar (2 m, dismantling) without shoes as well. BMI was calculated as weight in kilogram divided by the square of height in meter. WC was measured using a measuring tape in standing position at the midpoint between the lowest rib and the iliac crest. Weight status of each subject was categorized using the new WHO growth reference 5—19 years [20]. Body fat mass (BFM) was derived from total body water measured by isotope dilution technique using deuterium oxide [21]. Systolic and diastolic blood pressure (SBP and DBP) were measured by Pediatric Doctor using a standard pediatric sphygmomanometer at nearest 2 mm Hg. At least two measurements were taken on the right arm in seated position after 5 min rest and in optimal room conditions. The mean of the two measurements was considered as final blood pressure. The blood-pressure status of each adolescent was determined using the North American criteria for hypertension and prehypertension, which take into account the gender, age and height percentile [22]. All statistical analyses were performed using statistical package for social sciences (SPSS, version 17.0). The normal distribution of the variables was checked by the Shapiro—Wilk test. For each variable, the mean ± SD or median (25—75%
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interquartiles) were determined using descriptive statistics (Table 1). We used Mann—Whitney test and Kruskal—Wallis test to evaluate the effect of gender and both weight status and blood-pressure status on variables. To assess the relationship between obesity measures and blood pressure, we used Spearman test when the studied variables are normally or non-normally distributed and linear regression analysis when the variables do not have the same kind of distribution (Table 3). pValues < 0.05 were considered significant. There were 167 adolescents in the study population (44 boys and 123 girls) whose characteristics are presented in the Table 1. The characteristics of the study population according to blood-pressure status are shown in Table 2. Among the 167 adolescents, 29 (17.4%) were hypertensive and 16 (9.6%) had prehypertension. The percentage of prehypertensives and hypertensives appeared to be higher in boy than girls mainly in overweight groups whose sizes are nearly similar −14.3% versus 7.1% and 38.1% versus 14.3% respectively. Statistical analyses showed that BMI, WC and SBP were significantly higher in boys than girls (p ≤ 0.013). Also, BMI, WC, BFM, SBP and DBP were significantly higher in overweight-obese groups compared to healthy-weight groups (p ≤ 0.002). Similarly SBP and DBP were higher in groups with prehypertension (pre-HT) and hypertension (HT) compared to normotensives ones (p ≤ 0.005), while
Table 1
there was no significant difference for other variables between these groups. Table 3 shows the correlation coefficient between obesity measures and blood pressures. BMI was significantly correlated with SBP in both boys and girls of the study population (p ≤ 0.005) and overweight girls (p = 0.019). Similarly BMI was correlated with DBP in girls of the study population (p < 0.001), in obese boys (p = 0.05), in healthy weight and overweight girls (p = 0.043; p = 0.005 respectively). WC was highly correlated with SBP in both boys and girls of the study population (p = 0.017; p < 0.001 respectively) and in healthy weight girls (p = 0.001), while it was significantly associated with DBP only in girls of the study population and healthy weight group (p < 0.001; p = 0.001 respectively). BFM showed high significant association with SBP in both boys and girls of the study population (p = 0.003; p = 0.001 respectively), in obese boys and overweight girls (p = 0.036; p = 0.003). In addition, a positive correlation was seen between BFM and DBP in girls of the study population and obese boys as well (p = 0.007; p = 0.015 respectively). Our results showed that the prevalence of HT and pre-HT was 17.4% and 9.6% respectively in the study population. Among overweight-obese adolescents it was 30% and 10% respectively. These results are in agreement with data of previous studies. It was reported that 21.8% of European
Characteristics of the study population.
Variables
Total (n = 44)
Healthy weight (n = 17)
Boys Age (years) Weight (kg) Height (m) BMI (kg/m2 ) WC (cm) BFM (kg) SBP (mm Hg) DBP (mm Hg)
14.2 ± 0.9 61.6 ± 13.2 1.6 ± 0.1 23.5 ± 0.9 81.3 ± 11.9 19.1 (12.1—22.9) 120 ± 18 71 (61—80)
14.4 55.0 1.65 20.1 72.4 10.6 110 66
Variables
Total (n = 123)
Healthy weight (n = 80)
Overweight (n = 28)
Girls Age (years) Weight (kg) Height (m) BMI (kg/m2 ) WC (cm) BFM (kg) SBP (mm Hg) DBP (mm Hg)
14.2 (13.3—15.0) 51.0 (45.0—65.0) 1.58 ± 0.1 20.6 (18.2—24.0) 74.0 (66.0—84.0) 15.0 (10.5—22.7) 112 (100—120) 70 (60—77)
13.9 (13.2—15.0) 47.4 ± 7.3 1.58 ± 0.08 19.0 ± 2.1 68.5 (63.0—74.0) 12.3 (9.6—16.2) 110 (100—120) 70 (60—74)
14.6 62.8 1.59 24.6 83.7 22.5 116 70
± ± ± ± ± ± ± ±
0.8 10.0 0.11 2.3 8.4 5.9 14 14
Overweight (n = 21)
Obese (n = 6)
14.3 (13.5—14.7) 62.4 ± 9.6 1.60 ± 0.12 24.3 ± 1.5 82.4 ± 6.6 20.3 (18.2—22.8) 128 ± 15 75 (67—86)
14.2 77.6 1.59 30.2 102.3 33.8 123 77
± ± ± ± ± ± ± ±
1.2 8.7 0.07 1.9 7.5 5.2 12 9
± ± ± ± ± ± ± ±
0.9 19.0 0.09 3.7 5.7 11.8 25 13
Obese (n = 15) 14.5 ± 1.2 79.3 ± 10.2 1.60 ± 0.06 31.0 ± 3.0 95.0 ± 10.0 33.9 ± 10.1 125 ± 12 80 (70—80)
Data are mean ± SD for variables normally distributed, or median (25—75% interquartiles) for those non-normally distributed.
Prevalence of elevated blood pressure Table 2
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Characteristics of the study population according to blood-pressure status.
Boys Normotension Prehypertension Hypertension
Girls Normotension Prehypertension Hypertension
Total (n = 44)
Healthy weight (n = 17)
Overweight (n = 21)
Obese (n = 6)
27 (61.4%) 6 (13.6%) 11 (25.0%)
13 (76.5%) 3 (17.6%) 1 (5.9%)
10 (47.6%) 3 (14.3%) 8 (38.1%)
4 (66.7%) — 2 (33.3%)
Total (n = 123)
Healthy weight (n = 80)
Overweight (n = 28)
Obese (n = 15)
95 (77.2%) 10 (8.1%) 18 (14.6%)
66 (82.5%) 7 (8.8%) 7 (8.8%)
22 (78.6%) 2 (7.1%) 4 (14.3%)
7 (46.7%) 1 (6.7%) 7 (46.7%)
Data are expressed as n (%).
Table 3
Correlation coefficient of SBP and DBP with BMI, WC and BFM. BMI
Boys Total (n = 44) Healthy weight (n = 17) Overweight (n = 21) Obese (n = 6) Girls Total (n = 123) Healthy weight (n = 80) Overweight (n = 28) Obese (n = 15) * **
WC
SBP
DBP
0.415** 0.425 0.268 0.696
0.281 0.183 0.546 0.812*
0.449** 0.194 0.440* 0.074
0.335** 0.226* 0.512** 0.033
SBP
BFM DBP
SBP
DBP
0.357* 0.386 0.265 0.580
0.192 0.285 0.194 0.406
0.441** 0.235 0.025 0.754*
0.190 −0.028 −0.099 0.899*
0.518** 0.369** 0.373 −0.020
0.359** 0.364** 0.253 0.245
0.408** 0.079 0.612** 0.246
0.243** 0.172 0.132 0.107
Correlation is significant at the 0.05 level. Correlation is significant at the 0.01 level.
obese children aged 5—18 years were hypertensive [23] and 19.5% of Canadian children aged 4—17 years with excess weight were found to be hypertensive [24]. Also, Benmohammed et al. [25] found that the prevalence of HT and pre-HT among 305 Algerian overweight-obese adolescents was 19.7 and 11.1% respectively. One of our most important findings is the higher prevalence of HT among Moroccan overweight-obese adolescents compared to the same age-groups of some other countries. Moreover, knowing the prevalence of HT for the whole Moroccan population estimated to be 10.5% in 2003—2004 [26], there was high rates of hypertensive and pre-hypertensive adolescents among healthy-weight group (8.2 and 10.3% respectively). Values of WC, BFM, SBP and DBP were significantly higher in overweight and obese adolescents. These results are consistent with earlier report that noted the greater tendency for central fat deposition and higher blood pressure associated with overweight and obesity [27]. Also an independent association between high blood pressure and both
overweight and obesity was found by Burke et al. [28] in a prospective study carried out in an Australian cohort of children and adolescents followed up from 9 to 25 years. In another study, a significant correlation between blood pressure and BMI was observed in children and adolescents aged 7—17 years [4]. Regarding the gender’s effect on blood pressure, it was seen only in overweight groups, in which SBP was significantly higher in boys than girls. These findings are consistent with previous studies indicating that a significant positive correlation between adiposity and blood pressure was observed in boys but not in girls [25,29]. A significant association between WC and blood pressures was observed in different groups of the study population mainly in girls. These findings confirm the results of previous studies which reported that the accumulation of body fat in the abdominal region was established to predict well the health risks including high blood pressure [30,31]. Also, an independent association between elevated blood pressure and WC in a cohort of 2860 adolescents
e288 aged 11—17 years has been reported in another study [32]. BFM showed a significant relationship with blood pressure mainly with SBP. These results are in agreement with those reported in a study from China which concluded that blood pressure particularly SBP is positively associated with measures of adiposity in a sample of children and adolescents [33]. However, BFM was not associated as strongly as BMI and WC with blood pressure. Otherwise, the relationship of blood pressure with BMI was more important than with WC. These findings differ in some respects from those of a previous studies suggesting that WC identifies a greater number of children with elevated blood pressure than BMI [34,35]. However, they agree with those reported in recent study in which BMI was found to be better measurement than WC in predicting cardiovascular risks in adolescents [36]. In conclusion, the prevalence of hypertension was higher in boys than girls and in overweightobese than healthy-weight adolescents. Overall SBP and DBP were associated with BFM, BMI and WC. However, the strong association between these variables was seen in girls, and the greater risk of developing hypertension could be associated with increasing BMI. One of the main limitations of the current study was the relatively small sizes of the study population and weight status groups particularly for boys, because the recruitment of subjects was hampered during the course of the study. Another limitation is that the relationship between obesity measures and blood pressure may depend on pubertal stages that were not addressed in our study. The last limitation is that, although two measurements of blood pressure were taken and their mean was considered as final blood pressure, the HT and pre-HT needs to be confirmed at least by an another visit.
Conflict of interest All authors declare that they have no conflict of interest.
Acknowledgements Authors are grateful to the International Atomic Energy Agency (IAEA) for providing financial and technical support, and to all the study participants. The authors are also grateful to all of our team members for their hard work and valuable contribution, and to the editors of Obesity Research &
S. Mehdad et al. Clinical Practice for evaluating the current paper before its acceptance for publication.
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Available online at www.sciencedirect.com
SHORT REPORT
Prevalence of elevated blood pressure and its relationship with fat mass, body mass index and waist circumference among a group of Moroccan overweight adolescents Slimane Mehdad a,∗, Abdeslam Hamrani a, Khalid El Kari a, Asmaa El Hamdouchi a, Mohammed El Mzibri a, Amina Barkat a,b, Hassan Aguenaou a, Najat Mokhtar a a
Unité Mixte de Recherche en Nutrition et Alimentation, URAC39 (Université Ibn Tofaïl Kenitra — Centre National de l’Energie, des Sciences et Techniques Nucléaires), Morocco b Equipe de Recherche en santé et nutrition du couple mère- nouveau-né, Faculté de Médecine et de Pharmacie, Rabat, Morocco Received 17 December 2011 ; received in revised form 31 January 2012; accepted 8 February 2012
KEYWORDS Adolescents; Blood pressure; Body mass index; Fat mass; Hypertension; Obesity; Overweight; Waist circumference
Summary This study aimed to estimate the prevalence of hypertension among a group of adolescents and to assess the relationship of systolic and diastolic blood pressure (SBP, DBP) with body fat mass (BFM), body mass index (BMI) and waist circumference (WC). A total of 167 subjects aged 11—17 years were recruited, 29.3% and 12.6% were overweight and obese respectively. BMI, WC, SBP and DBP were determined using standardized equipment. BFM was estimated by the deuterium oxide dilution. Hypertension (HT) and prehypertension (pre-HT) were observed in 17.4% and 9.6%, of the study population, respectively. The prevalence of HT and pre-HT was significantly higher in boys and in overweight-obese groups (p = 0.044; p = 0.003 respectively). Both SBP and DBP were significantly higher in overweight-obese compared to healthy-weight groups (p < 0.001; p = 0.002 respectively). SBP was significantly higher in boys than girls (p = 0.013). With some exceptions, SBP and DBP were
Abbreviations: BMI, body mass index; BFM, body fat mass; DBP, diastolic blood pressure; HT, hypertension; pre-HT, prehypertension; SBP, systolic blood pressure; SD, standard deviation; WC, waist circumference; WHO, World Health Organization. ∗ Corresponding author at: URAC 39, CNESTEN, BP 1382 Madinat Al Irfane, Rabat 10001, Morocco. Tel.: +212 672 210 338/537 217 635; fax: +212 537 217 670/34. E-mail addresses: [email protected] (S. Mehdad), [email protected] (A. Hamrani), [email protected] (K.E. Kari), [email protected] (A.E. Hamdouchi), [email protected] (M.E. Mzibri), [email protected] (A. Barkat), [email protected] (H. Aguenaou), [email protected] (N. Mokhtar). 1871-403X/$ — see front matter © 2012 Asian Oceanian Association for the Study of Obesity. Published by Elsevier Ltd. All rights reserved.
doi:10.1016/j.orcp.2012.02.006
Prevalence of elevated blood pressure
e285
significantly correlated with BMI, WC and BFM in the study population and different weight-status groups of both genders. The relationship of blood pressure with BMI appeared to be more significant than with WC and BFM. The prevalence of hypertension was higher in boys than girls and in overweight-obese than healthy-weight adolescents. Overall SBP and DBP were associated with BFM, BMI and WC. However, the strong association between these variables was seen in girls, and the greater risk of developing hypertension could be associated with increasing BMI. © 2012 Asian Oceanian Association for the Study of Obesity. Published by Elsevier Ltd. All rights reserved.
The increasing prevalence of obesity and overweight among adolescents has led to a surge of several chronic illnesses such as type 2 diabetes mellitus [1,2], high levels of blood pressure [3,4], adiposity-associated morbidity [5] and dyslipidemia [6,7]. Moreover obesity and the associated metabolic abnormalities generally seen in a young age have a high risk to remain into adulthood [8,9]. Thus childhood overweight and obesity are considered as critical public health problems [10]. It has been shown repeatedly that obesity measurements had strong relationship with risks of chronic diseases in adults [11,12]. Some studies indicated that overweight and obese children and adolescents have systematically higher levels of blood pressure than their healthy weight counterparts [13,14]. However, it is not yet clear whether this relationship between blood pressure and weight status can be also found in adolescents of all ethnic groups. Epidemiological studies have found a progressive increasing of elevated blood pressure prevalence with increasing adipose tissue [15] and a close relationship between increased abdominal obesity assessed by waist circumference and metabolic risk factors in adults [16,17]. Nevertheless few studies explored this association in adolescents [18,19]. The current study aimed to estimate the prevalence of hypertension among a group of adolescents from Rabat region. It also aimed to explore, for the first time to our knowledge, the relationship between blood pressure and each of body fat mass (BFM), body mass index (BMI) and waist circumference (WC), and to identify which of these obesity measures could be the best predictor of elevated blood pressure. The study protocol was approved by the relevant national authorities. Seven secondary schools randomly selected in the Rabat region (Morocco) were involved in the study. A systematic random sampling procedure was used to select the subjects who were invited to participate in the study. As
the number of overweight or obese adolescents was very low, a further stratification according to their weight status was used. Each of healthy weight and overweight/obese groups were selected separately among their peers in each school using a simple random sampling design. A total of 167 adolescents (123 girls and 44 boys) aged 11—17 years were recruited. Informed consents were obtained from their parents. Standardized equipment was used by trained operators to take anthropometric measurements. Body weight was measured to the nearest 0.1 kg using Seca Model 770 digital electronic scale with minimal clothing and without shoes. Height was measured to the nearest 0.1 cm using a height bar (2 m, dismantling) without shoes as well. BMI was calculated as weight in kilogram divided by the square of height in meter. WC was measured using a measuring tape in standing position at the midpoint between the lowest rib and the iliac crest. Weight status of each subject was categorized using the new WHO growth reference 5—19 years [20]. Body fat mass (BFM) was derived from total body water measured by isotope dilution technique using deuterium oxide [21]. Systolic and diastolic blood pressure (SBP and DBP) were measured by Pediatric Doctor using a standard pediatric sphygmomanometer at nearest 2 mm Hg. At least two measurements were taken on the right arm in seated position after 5 min rest and in optimal room conditions. The mean of the two measurements was considered as final blood pressure. The blood-pressure status of each adolescent was determined using the North American criteria for hypertension and prehypertension, which take into account the gender, age and height percentile [22]. All statistical analyses were performed using statistical package for social sciences (SPSS, version 17.0). The normal distribution of the variables was checked by the Shapiro—Wilk test. For each variable, the mean ± SD or median (25—75%
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interquartiles) were determined using descriptive statistics (Table 1). We used Mann—Whitney test and Kruskal—Wallis test to evaluate the effect of gender and both weight status and blood-pressure status on variables. To assess the relationship between obesity measures and blood pressure, we used Spearman test when the studied variables are normally or non-normally distributed and linear regression analysis when the variables do not have the same kind of distribution (Table 3). pValues < 0.05 were considered significant. There were 167 adolescents in the study population (44 boys and 123 girls) whose characteristics are presented in the Table 1. The characteristics of the study population according to blood-pressure status are shown in Table 2. Among the 167 adolescents, 29 (17.4%) were hypertensive and 16 (9.6%) had prehypertension. The percentage of prehypertensives and hypertensives appeared to be higher in boy than girls mainly in overweight groups whose sizes are nearly similar −14.3% versus 7.1% and 38.1% versus 14.3% respectively. Statistical analyses showed that BMI, WC and SBP were significantly higher in boys than girls (p ≤ 0.013). Also, BMI, WC, BFM, SBP and DBP were significantly higher in overweight-obese groups compared to healthy-weight groups (p ≤ 0.002). Similarly SBP and DBP were higher in groups with prehypertension (pre-HT) and hypertension (HT) compared to normotensives ones (p ≤ 0.005), while
Table 1
there was no significant difference for other variables between these groups. Table 3 shows the correlation coefficient between obesity measures and blood pressures. BMI was significantly correlated with SBP in both boys and girls of the study population (p ≤ 0.005) and overweight girls (p = 0.019). Similarly BMI was correlated with DBP in girls of the study population (p < 0.001), in obese boys (p = 0.05), in healthy weight and overweight girls (p = 0.043; p = 0.005 respectively). WC was highly correlated with SBP in both boys and girls of the study population (p = 0.017; p < 0.001 respectively) and in healthy weight girls (p = 0.001), while it was significantly associated with DBP only in girls of the study population and healthy weight group (p < 0.001; p = 0.001 respectively). BFM showed high significant association with SBP in both boys and girls of the study population (p = 0.003; p = 0.001 respectively), in obese boys and overweight girls (p = 0.036; p = 0.003). In addition, a positive correlation was seen between BFM and DBP in girls of the study population and obese boys as well (p = 0.007; p = 0.015 respectively). Our results showed that the prevalence of HT and pre-HT was 17.4% and 9.6% respectively in the study population. Among overweight-obese adolescents it was 30% and 10% respectively. These results are in agreement with data of previous studies. It was reported that 21.8% of European
Characteristics of the study population.
Variables
Total (n = 44)
Healthy weight (n = 17)
Boys Age (years) Weight (kg) Height (m) BMI (kg/m2 ) WC (cm) BFM (kg) SBP (mm Hg) DBP (mm Hg)
14.2 ± 0.9 61.6 ± 13.2 1.6 ± 0.1 23.5 ± 0.9 81.3 ± 11.9 19.1 (12.1—22.9) 120 ± 18 71 (61—80)
14.4 55.0 1.65 20.1 72.4 10.6 110 66
Variables
Total (n = 123)
Healthy weight (n = 80)
Overweight (n = 28)
Girls Age (years) Weight (kg) Height (m) BMI (kg/m2 ) WC (cm) BFM (kg) SBP (mm Hg) DBP (mm Hg)
14.2 (13.3—15.0) 51.0 (45.0—65.0) 1.58 ± 0.1 20.6 (18.2—24.0) 74.0 (66.0—84.0) 15.0 (10.5—22.7) 112 (100—120) 70 (60—77)
13.9 (13.2—15.0) 47.4 ± 7.3 1.58 ± 0.08 19.0 ± 2.1 68.5 (63.0—74.0) 12.3 (9.6—16.2) 110 (100—120) 70 (60—74)
14.6 62.8 1.59 24.6 83.7 22.5 116 70
± ± ± ± ± ± ± ±
0.8 10.0 0.11 2.3 8.4 5.9 14 14
Overweight (n = 21)
Obese (n = 6)
14.3 (13.5—14.7) 62.4 ± 9.6 1.60 ± 0.12 24.3 ± 1.5 82.4 ± 6.6 20.3 (18.2—22.8) 128 ± 15 75 (67—86)
14.2 77.6 1.59 30.2 102.3 33.8 123 77
± ± ± ± ± ± ± ±
1.2 8.7 0.07 1.9 7.5 5.2 12 9
± ± ± ± ± ± ± ±
0.9 19.0 0.09 3.7 5.7 11.8 25 13
Obese (n = 15) 14.5 ± 1.2 79.3 ± 10.2 1.60 ± 0.06 31.0 ± 3.0 95.0 ± 10.0 33.9 ± 10.1 125 ± 12 80 (70—80)
Data are mean ± SD for variables normally distributed, or median (25—75% interquartiles) for those non-normally distributed.
Prevalence of elevated blood pressure Table 2
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Characteristics of the study population according to blood-pressure status.
Boys Normotension Prehypertension Hypertension
Girls Normotension Prehypertension Hypertension
Total (n = 44)
Healthy weight (n = 17)
Overweight (n = 21)
Obese (n = 6)
27 (61.4%) 6 (13.6%) 11 (25.0%)
13 (76.5%) 3 (17.6%) 1 (5.9%)
10 (47.6%) 3 (14.3%) 8 (38.1%)
4 (66.7%) — 2 (33.3%)
Total (n = 123)
Healthy weight (n = 80)
Overweight (n = 28)
Obese (n = 15)
95 (77.2%) 10 (8.1%) 18 (14.6%)
66 (82.5%) 7 (8.8%) 7 (8.8%)
22 (78.6%) 2 (7.1%) 4 (14.3%)
7 (46.7%) 1 (6.7%) 7 (46.7%)
Data are expressed as n (%).
Table 3
Correlation coefficient of SBP and DBP with BMI, WC and BFM. BMI
Boys Total (n = 44) Healthy weight (n = 17) Overweight (n = 21) Obese (n = 6) Girls Total (n = 123) Healthy weight (n = 80) Overweight (n = 28) Obese (n = 15) * **
WC
SBP
DBP
0.415** 0.425 0.268 0.696
0.281 0.183 0.546 0.812*
0.449** 0.194 0.440* 0.074
0.335** 0.226* 0.512** 0.033
SBP
BFM DBP
SBP
DBP
0.357* 0.386 0.265 0.580
0.192 0.285 0.194 0.406
0.441** 0.235 0.025 0.754*
0.190 −0.028 −0.099 0.899*
0.518** 0.369** 0.373 −0.020
0.359** 0.364** 0.253 0.245
0.408** 0.079 0.612** 0.246
0.243** 0.172 0.132 0.107
Correlation is significant at the 0.05 level. Correlation is significant at the 0.01 level.
obese children aged 5—18 years were hypertensive [23] and 19.5% of Canadian children aged 4—17 years with excess weight were found to be hypertensive [24]. Also, Benmohammed et al. [25] found that the prevalence of HT and pre-HT among 305 Algerian overweight-obese adolescents was 19.7 and 11.1% respectively. One of our most important findings is the higher prevalence of HT among Moroccan overweight-obese adolescents compared to the same age-groups of some other countries. Moreover, knowing the prevalence of HT for the whole Moroccan population estimated to be 10.5% in 2003—2004 [26], there was high rates of hypertensive and pre-hypertensive adolescents among healthy-weight group (8.2 and 10.3% respectively). Values of WC, BFM, SBP and DBP were significantly higher in overweight and obese adolescents. These results are consistent with earlier report that noted the greater tendency for central fat deposition and higher blood pressure associated with overweight and obesity [27]. Also an independent association between high blood pressure and both
overweight and obesity was found by Burke et al. [28] in a prospective study carried out in an Australian cohort of children and adolescents followed up from 9 to 25 years. In another study, a significant correlation between blood pressure and BMI was observed in children and adolescents aged 7—17 years [4]. Regarding the gender’s effect on blood pressure, it was seen only in overweight groups, in which SBP was significantly higher in boys than girls. These findings are consistent with previous studies indicating that a significant positive correlation between adiposity and blood pressure was observed in boys but not in girls [25,29]. A significant association between WC and blood pressures was observed in different groups of the study population mainly in girls. These findings confirm the results of previous studies which reported that the accumulation of body fat in the abdominal region was established to predict well the health risks including high blood pressure [30,31]. Also, an independent association between elevated blood pressure and WC in a cohort of 2860 adolescents
e288 aged 11—17 years has been reported in another study [32]. BFM showed a significant relationship with blood pressure mainly with SBP. These results are in agreement with those reported in a study from China which concluded that blood pressure particularly SBP is positively associated with measures of adiposity in a sample of children and adolescents [33]. However, BFM was not associated as strongly as BMI and WC with blood pressure. Otherwise, the relationship of blood pressure with BMI was more important than with WC. These findings differ in some respects from those of a previous studies suggesting that WC identifies a greater number of children with elevated blood pressure than BMI [34,35]. However, they agree with those reported in recent study in which BMI was found to be better measurement than WC in predicting cardiovascular risks in adolescents [36]. In conclusion, the prevalence of hypertension was higher in boys than girls and in overweightobese than healthy-weight adolescents. Overall SBP and DBP were associated with BFM, BMI and WC. However, the strong association between these variables was seen in girls, and the greater risk of developing hypertension could be associated with increasing BMI. One of the main limitations of the current study was the relatively small sizes of the study population and weight status groups particularly for boys, because the recruitment of subjects was hampered during the course of the study. Another limitation is that the relationship between obesity measures and blood pressure may depend on pubertal stages that were not addressed in our study. The last limitation is that, although two measurements of blood pressure were taken and their mean was considered as final blood pressure, the HT and pre-HT needs to be confirmed at least by an another visit.
Conflict of interest All authors declare that they have no conflict of interest.
Acknowledgements Authors are grateful to the International Atomic Energy Agency (IAEA) for providing financial and technical support, and to all the study participants. The authors are also grateful to all of our team members for their hard work and valuable contribution, and to the editors of Obesity Research &
S. Mehdad et al. Clinical Practice for evaluating the current paper before its acceptance for publication.
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