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Hypertension and obesity in Italian school children: The role of diet, lifestyle and family history
Nutrition, Metabolism & Cardiovascular Diseases (2015) xx, 1e6
Available online at www.sciencedirect.com
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Hypertension and obesity in Italian school children: The role of diet, lifestyle and family history* E. Menghetti a, P. Strisciuglio b,*, A. Spagnolo c, M. Carletti d, G. Paciotti c, G. Muzzi e, M. Beltemacchi f, D. Concolino e, M. Strambi g, A. Rosano c a
Study Group on Hypertension, University “La Sapienza”, Rome, Italy Department of Pediatrics, University Federico II, Naples, Italy c ISFOL, Dipartimento Lavoro e Politiche Sociali, Rome, Italy d Human Physiology, University of Insubria, Italy e Department of Pediatrics, University “Magna Grecia”, Catanzaro, Italy f Department of Sport Medicine, Varese, Italy g Department of Molecular and Development Medicine, University of Siena, Italy b
Received 25 July 2014; received in revised form 6 February 2015; accepted 20 February 2015 Available online - - -
KEYWORDS Hypertension; Obesity; Students; Italy
Abstract Background and aims: In Italy, the prevalence of hypertension, obesity and overweight in paediatric patients has increased in the past years. The purpose of this study was to analyse the relationship between obesity and hypertension and related factors in Italian students. Methods and results: We studied 2007 healthy individuals between the ages of 6 and 17 years of age (998 males and 1009 females) attending schools in the cities of Varese (northern Italy), Rome (central Italy) and Catanzaro (southern Italy). The blood pressure, weight and height of the students were measured. We also assessed their daily intake of foods and the amount of physical activity they performed. A questionnaire was administered to the parents of the subjects to obtain information on the child’s medical history and family lifestyle. Of the students, 27.2% were overweight, and 6.6% were obese, with the highest percentages in southern Italy. A total of 6.2% of students had hypertension, and the region with the highest percentage was found to be northern Italy. Obese students had a risk of developing hypertension that was four times greater than those subjects who were of normal weight. Conclusion: Overweight and obese children/adolescents were more frequently found in southern Italy as opposed to northern and central Italy, and hypertensive children were more prevalent in the north. An unhealthy diet might explain the more widely spread obesity among children living in the south; an excess use of salt could explain the greater rate of hypertension found among children/adolescents living in the north. ª 2015 Elsevier B.V. All rights reserved.
Introduction The importance of measuring blood pressure (BP) in childhood and adolescence has been widely recognized
*
No honorarium, grant or other form of payment was given to any of the authors for the production of the manuscript. * Corresponding author. E-mail address: [email protected] (P. Strisciuglio).
[1,2]; elevated BP in children may be an early sign of essential (or primary) hypertension and childhood BP levels are predictive of adult levels [3,4]. In Italy, as in other economically developed countries, the prevalence of childhood hypertension has increased in the past years, from 2% to approximately 6% [5]. Even so, essential paediatric hypertension remains largely underdiagnosed and undertreated, and few studies have reported its prevalence and risk factors in children and adolescents. The prevalence of obesity and overweight children/adolescents has
http://dx.doi.org/10.1016/j.numecd.2015.02.009 0939-4753/ª 2015 Elsevier B.V. All rights reserved.
Please cite this article in press as: Menghetti E, et al., Hypertension and obesity in Italian school children: The role of diet, lifestyle and family history, Nutrition, Metabolism & Cardiovascular Diseases (2015), http://dx.doi.org/10.1016/j.numecd.2015.02.009
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also increased, now amounting to approximately 36% of Italian primary school children [6]. The aim of the present study was to assess the correlation between hypertension and obesity in a population of Italian students between 6 and 17 years of age located in three Italian cities representative of northern, central and southern Italy and to identify early those at risk of developing cardiovascular disease in adulthood. Methods A total of 2272 elementary-, middle- and high-school students in the cities of Varese, Rome and Catanzaro (located in northern, central and southern Italy, respectively) were enrolled in the study. They ranged in age from 6 to 17 years of age and were uniformly distributed among the three cities. Participation was voluntary. Informed, written consent was obtained from the parents of all participants and from the council board of the students’ schools. Two hundred twenty-seven students were excluded from the study because their parents refused to provide written consent (they did not want their children to be weighed and measured wearing only underwear). Another 38 children/adolescents were excluded because their measurements could not be fully taken. The final sample consisted of 2007 healthy students (998 males and 1009 females). Teams of medical researchers in the three zones all received specific training to standardize data-collection methodology, including the measurement of weight, height and blood pressure. All measurements were taken at the schools between 10:00 AM and 12:00 PM Body mass index (BMI), was used to determine whether a child was overweight or obese, according Cole et al.’s tables [7]. Weight and height were measured according to WHO recommendations, with the students in their underwear [8]. Body weight was measured in kilograms on a calibrated digital scale and height was measured in centimetres using a stadiometer. Blood pressure (BP) was measured using a mercury sphygmomanometer with the appropriate cuff for the subject’s upper arm size [9]. BP values were approximated to two mm Hg. Systolic BP was defined as the first Korotkoff sound (appearance of sounds), and diastolic BP was defined as the fifth Korotkoff sound (disappearance of sounds). Following these BP measurements, two other measurements were taken, 1 min apart from the other, using the method that we previously tested and used [10] on the right arm and with the student sitting down. BP was categorized according to the guidelines set out in the Fourth Report of the Task Force on Hypertension [11], using age and height percentiles. Normotension was defined when BP was under the 90th percentile, prehypertension was defined as a BP in the 90e95th percentile, and hypertension was defined as a BP greater than the 95th percentile.
E. Menghetti et al.
All children/adolescents that were found to have high blood pressure values or to be hypertensive or prehypertensive were rechecked after one week, and if the high pressure values persisted, they were rechecked a third time for a final measurement. Each student was also asked to fill out a detailed questionnaire to obtain information regarding diet, and the number of hours spent daily watching television and using a computer (number of hours per day), and performing physical activity and extracurricular sports (number of hours per week). We collected information on the frequency of breakfast consumption and the intake of the following food: fruit, cooked and fresh vegetables, bread and pasta, meat, fish, milk, cold cuts, potatoes, cheese, eggs, salty and sweet sneaks. All of these data were collected through a questionnaire completed by students and their parents and the answers were given using a scale ranging from 1 (seldom or never) to 4 (every day consumption). This method had been previously validated [12]. Children between 6 and 12 years of age filled out the questionnaire with the assistance of nurses. Two composite scores, the first on diet habits and the second on sedentary habits, were obtained using a linear combination of the values corresponding to the answers derived from a factor analysis (FA), and taking into account the coefficients of the first component 0.05. FA was used to analyse the relationship between variables (food or sedentary habits) because it is extremely useful in discriminating between individuals based on the characteristics included in this analysis [13]. The composite scores were then recalculated in quartiles; quartile values (1 Z unhealthy diet/sedentary; 2e4 Z healthy diet/not sedentary) were used in the logistic models. Parents were also asked to fill out a questionnaire regarding their own age, weight, and height, the presence of essential hypertension, and the birth weight and gestational age of their children. Pearson’s correlation coefficient was performed to assess the correlations between BMI, hypertension and the selected variable. A p-value equal or less than 0.05 was considered to be significant. A logistic model was used to assess the relationship between hypertension and obesity and between obesity, hypertension and selected factors (sedentary lifestyle, and an unhealthy diet) that were possibly related; the association was measured as odds ratios (OR) with 95% confidence intervals (95% CI), using subjects of normal weight as a reference, adjusting for sex and stratifying by the city in which the interviews were collected. The heterogeneity of the distribution of obesity and hypertension among the students by gender and geographic area was tested using a chi-square test, with a significance level set at 5%. Results The size of the sample allowed us to detect a risk of hypertension among obese children and adolescents with an
Please cite this article in press as: Menghetti E, et al., Hypertension and obesity in Italian school children: The role of diet, lifestyle and family history, Nutrition, Metabolism & Cardiovascular Diseases (2015), http://dx.doi.org/10.1016/j.numecd.2015.02.009
Hypertension and obesity in Italian school children
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odds ratio of 2.5. The expected prevalence of obesity was 5%, and the expected prevalence of hypertension among non-obese children was 6%, with a confidence level of 95% and a power of 80%. Of the participating students, 27.2% were overweight, with a higher percentage among males (30.5%) compared with females (25.0%), and in southern Italy (34.0%), compared with the northern (19.1%) and central regions (28.7%). Six percent (6.6%) were obese, with a higher percentage among males (7.9%) and in southern Italy (9.6%) (Table 1). The number and percentage of children/adolescents with hypertension and prehypertension by gender, age group and geographic area is reported in Table 2. Hypertension was more frequent among males (6.9%) and in northern Italy (10.0%). Prehypertension was also more frequent in northern Italy (12.1%) in both sexes. Regarding diet, the most commonly consumed foods were: pasta (94.8%), bread (83.1%), milk (75.4%), meat (72.9%), fruits (66.1%), vegetables (50.9%) and cold cuts (49.8%). The percentage of children adding salt to their meal was 41.6 in the north, 35.2 in the central region and 33,6 in the southern region (data not shown). Among male students, 79.9% reported that they ate breakfast regularly, compared with 74.6% of female students. The percentage was highest among 6- to 10-year-old children (83.5%) and tended to decrease with age (data not shown). Sports were practiced for more than 2 h per week by 43.6% of males and 29.3% of females. Per day, the mean time spent walking was 6e7 min in northern Italy, 10e11 min in southern Italy and 17e18 min in central Italy (data not shown). The coefficients derived from FA associated with food consumption and the habits of children are useful in discriminating between healthy/unhealthy food and healthy/unhealthy habits related to obesity and hypertension. Empirically, looking at the results of the FA represented on first two principal axes (Fig. 1), we can conclude that food with higher coefficients can be classified as healthy food (fruits: 0.532; salad: 0.530; and milk: 0.486), and food with negative coefficients can be classified as unhealthy food (sweet snacks: 0.330; and salted
snacks: 0.454). The frequency of breakfast consumption had a positive coefficient (0.498) that can be considered healthy; physical activities with positive coefficients (sport: 0.59) can be considered healthy, and those with negative coefficients are considered to be unhealthy (TV/ PC watching: 0,65). In the analysis of the association between obesity and an unhealthy diet and sedentary habits stratified by area, an unhealthy diet was still associated with obesity in the south (OR: 1.43; 95% CI: 1.04e1.96). Sedentary habits were associated with obesity in all areas, but more markedly in central Italy, although the association was still not statistically significant (Table 3). An unhealthy diet was associated with hypertension in southern Italy (OR: 1.43; 95% CI: 0.89e2.29) and was also associated with sedentary habits (OR: 1.34; 95% CI: 0.82e2.19), even if both associations were not statistically significant (Table 4). A strong relationship is present between obesity and hypertension in our sample, with 17.4% of obese children/ adolescents also presenting with hypertension. The risk of hypertension in obese children/adolescents (BP > 95th percentile) compared with normal-weight children/adolescents was much higher (OR Z 4.22; 95% C.I.: 2.56e6.93); and the risk for pre-hypertension (BP > 90th percentile) was similar (OR Z 4.20; 95% C.I. Z 2.82e6.26). The relationship between a child’s/adolescent’s obesity and that of their mother and father had an OR of 3.21 (95% CI: 1.92e5.34) and an OR of 3.25 (95% CI: 1.64e6.44), respectively. If both parents were obese, the OR for obese children was 10.64 (95% CI: 3.32e34.14). For hypertension, the OR was statistically significant only in the relationship between hypertension of the mother and the BP of children above the 90th percentile (OR: 1.96; 95% CI: 1.15e3.36). Finally we analysed the risk of hypertension among those who add salt to their food. The risk, adjusted for age and sex, was doubled among children living in the north (OR Z 2.0; 95% CI 1.05e3.85). Discussion
Table 1 Percentage of overweight and obese students by gender and geographic area. Area
Number of subjects Male Female Total Overweight Male Female Total Obese Male Female Total * Z p < 0.05.
North
Centre
South
Total
N 331 290 621 % 22.3* 15.6* 19.1 % 3.7 2.8 3.3
N 317 320 637 % 29.7 27.6 28.7 % 7.3 5.3 6.3
N 350 399 749 % 38.7* 29.8* 34.0 % 12.5* 7.1 9.6
N 998 1009 2007 % 30.5 25.0 27.2 % 7.9 5.5 6.6
We found a high incidence of obese and overweight children and adolescents. The incidence rate trended upward according to geography, moving from north to south; it was lowest in northern Italy, higher in central Italy and highest in southern Italy. Overall, the incidence rate was higher in males than in females, and 27.2% of our children/ adolescents (6e17 years) were overweight. The study of obese and overweight children is very important because these children often suffer from hypertension, hypercholesterolemia, hypertriglyceridemia and type 2 diabetes in addition to what is already in childhood called a “metabolic syndrome” [14]. The association between gestational weight gain, obesity and BP has been investigated and maternal gestational weight increase is an independent predictor of obesity in infancy, thus exposure to perinatal factors
Please cite this article in press as: Menghetti E, et al., Hypertension and obesity in Italian school children: The role of diet, lifestyle and family history, Nutrition, Metabolism & Cardiovascular Diseases (2015), http://dx.doi.org/10.1016/j.numecd.2015.02.009
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E. Menghetti et al.
Table 2 Number and percentage of students with hypertension, by gender, age-group and geographic area. Age
North Total number
Males 06e09 10e13 14e17 Total Females 06e09 10e13 14e17 Total
Centre Hyp
PreHy
%
%
Total number
South Hyp
PreHy
%
%
Total
Total number
Hyp
PreHy
%
%
1.8 4.1 19.1 7.1
2.7 4.7 22.5 8.6 2.6 6.6 8.6 5.5
107 81 143 331
3.7 17.3 10.5 10.0
3.7 17.3 12.6 10.9*
148 162 7 317
0.7 6.2 0.0 3.5*
1.4 0.6 14.3 1.3*
113 148 89 350
97 85 108 290
5.2 21.2 11,1 12.1*
7.2 7.1 13.0 9.3*
152 160 8 320
0.7 5.0 0.0 2.8
1.3 5.6 12.5 3.8
151 167 81 399
3.3 3.6 0.0 2.8*
Total number
Hyp
PreHy
%
%
368 391 239 998
1.9 7.7 13.4 6.9
2.4 5.6 16.3 7.0
400 412 197 1009
2.8 7.8 6.1 5.5
3.3 6.3 11.2 6.0
Hy Z Hypertension; PreHy Z PreHypertension; NHy Z No Hypertension. * Z p < 0.05.
should be taken into account for the early prevention of excessive weight gain and obesity [15]. We found that hypertension was more prevalent in northern Italy compared with central and southern Italy. Prehypertension [16e19] was found in a high percentage of children (7%), indicating that young people should be monitored to prevent them from gaining excess weight. Although these percentages are consistent with the nearly 6% reported in national and international case studies [20e22], they are much higher than the 1% reported in a study undertaken in Italy in 1981 [23]. In recent years, numerous studies focusing on obesity and hypertension have emphasized the great hazard posed by the significant increase in these pathological situations, in specific, the risk of a shortened life span [14]. Our results demonstrate the nutritional aspects involved in obesity. We found that the majority of the children who
participated in the study ate breakfast, especially children 6e10 years of age. The study also found that eating fruit and salad has a protective effect against hypertension. It is well known that salt consumption can affect BP [24]. In our study, salt consumption was higher in northern Italy than it was in other areas; and the risk of hypertension doubled among salt consumers. Finally, in our sample, children who performed little physical activity spent many afternoon hours in front of the television and/or computer. They also had an unhealthy diet, which is consistent with the results of other studies [25,26]. Our data also confirm the close link between obesity and hypertension and the link between obesity and a lack of daily physical activity. In our study, hypertension was associated not only with obesity but also with the addition of salt to food and a lack of physical activity. Finally, eating breakfast seems to be important, as does reducing salt
Figure 1 Representation of foods on first two principal axes on the basis of factor analysis. Distribution by the coefficient derived from the association between food consumption and habits of children.
Please cite this article in press as: Menghetti E, et al., Hypertension and obesity in Italian school children: The role of diet, lifestyle and family history, Nutrition, Metabolism & Cardiovascular Diseases (2015), http://dx.doi.org/10.1016/j.numecd.2015.02.009
Hypertension and obesity in Italian school children
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Table 3 Association between obesity vs diet and sedentary habit, adjusted for sex and stratified by area. Odds ratios (OR) and 95% confidence intervals (CI). Area
Factors
OR
95% CI Inf
Obesity vs diet North Sex (male reference) Unhealthy diet (healthy diet reference) Costant Center Sex (male reference) Unhealthy diet (healthy diet reference) Costant South Sex (male reference) Unhealthy diet (healthy diet reference) Costant Obesity vs sedentary habit North Sex (male reference) Sedentary (not sedentary reference) Costant Center Sex (male reference) Sedentary (not sedentary reference) Costant South Sex (male reference) Sedentary (not sedentary reference) Costant
.524 1.431 .223 .858 .807 .471 .646 1.432 .539 .455 1.087 .293 .915 1.362 .348 .656 1.132 .591
Sup
.312 .881 .856 2.393 .588 1.251 .553 1.178 .472 .885 1.043 1.965
.270 .767 .660 1.788 .642 1.304 .954 1.946 .482 .892 .827 1.551
consumption, favouring the Mediterranean diet. An obese child presents a clear risk of becoming hypertensive or prehypertensive. That risk is four times greater than of a child of normal weight; it is thus very important to prevent excess weight gain in childhood [27]. Taking into account family history of obesity and hypertension, children have a three-times greater risk of being obese if one parent is obese; and if both parents are obese, the risk is ten times greater compared with that of children with
Table 4 Association between hypertension vs diet and sedentary habit, adjusted for sex and stratified by area. Odds Ratios (OR) and 95% confidence intervals (CI). Area
Factors
OR
95% CI Inf
Hypertension vs diet North Sex (male reference) Unhealthy diet (healthy diet reference) Costant Center Sex (male reference) Unhealthy diet (healthy diet reference) Costant South Sex (male reference) Unhealthy diet (healthy diet reference) Costant Hypertension vs sedentary habit North Sex (male reference) Sedentary (not sedentary reference) Costant Center Sex (male reference) Sedentary (not sedentary reference) Costant South Sex (male reference) Sedentary (not sedentary reference) Costant
1.048 1.165 .298 .746 .946 .066 2.108 1.429 .072 .939 .835 .326 1.411 1.063 .044 .458 1.344 .150
Sup
.675 1.628 .751 1.808 .367 1.517 .461 1.939 1.329 3.343 .890 2.292
.599 1.473 .528 1.319 .648 3.072 .495 2.281 .282 .743 .822 2.195
parents of normal weight [28]. Children of mothers with hypertension have a two-times greater risk of having blood pressure values in the upper 90th percentile [29]. Our data in some ways confirm the strict relationship between food habits, hypertension and lifestyle and suggest that policy actions should be implemented nationally to reduce the trend of increased hypertension and obesity in Italian children given the higher risk of cardiovascular events in adulthood [30]. References [1] Flynn JT. Ambulatory blood pressure monitoring in children: imperfect yet essential. Pediatr Nephrol 2011;26:2089e94. [2] Zinner SH, Rosner B, Oh W, Kass EH. Significance of blood pressure in infancy. Hypertension 1985;3:411e6. [3] Daniels SR. Cardiovascular sequelae of childhood hypertension. Am J Hypertens 2002;15(2):61Se2S. [4] Thompson M, Duma T, Bougatsos C, Blazina I, Norris SL. Screening for hypertension in children and adolescents to prevent cardiovascular disease. Pediatrics 2013;131:490e4. [5] Menghetti E, Carletti M, Strisciuglio P, Spagnolo A. High percentage of obesity during childhood and adolescence and subsequent increases in childhood arterial hypertension. Minerva Pediatr 2010;2:133e7. [6] Spinelli A, Lamberti A, Baglio G, Andreozzi S, Galeone D, et al. Sistema di sorveglianza su alimentazione e attività fisica nei bambini della scuola primaria. Risultati 2008. Okkio alla salute, http://www.epicentro.iss.it/okkio alla salute/default.asp. ISSN 1123-3111, Rapporto ISTISAN 09/24. [7] Cole TJ, Bellizzi MC, Flegal KM, Dietz WH. Establishing a standard definition for child overweight and obesity worldwide: international survey. Br Med J 2000;320:1240e3. [8] World Health Organitation. Physical status: the use and interpretation of anthropometry. Geneva: WHO; 1995. Tech Rep Ser; 854. [9] Arafat M, Mattoo TK. Measurement of blood pressure in children; recommendations and perceptions of cuff selection pediatrics. Pediatrics 1999;104:e30. [10] Spagnolo A, Strisciuglio P, Menghetti E. Annual follow-up of children and adolescents in Southern Italy. Int J Pediatr Obes 2010; Suppl 1:67. [11] National High Blood Pressure Education Program Working Group on High Blood Pressure in Children and Adolescents. Fourth report on the diagnosis, evaluation and treatment of high blood pressure in children and adolescents. Pediatrics 2004;114(Suppl. 2): 555e76. [12] D’Addesa D, D’Addezio L, Martone D, Censi L, Scanu A, Cairella G, et al. Dietary intake and physical activity of normal weight and overweight/obese adolescents. Int J Ped 2010:2e9. http: //dx.doi.org/10.1155/2010/785649. ID78549. [13] Schulze MB, Hoffmann K, Kroke A, Boeing H. An approach to construct simplified measures of dietary patterns from exploratory factor analysis. Br J Nutr 2003;89(3):409e19. [14] Bray GA, Bellanger T. Epidemiology, trends, and morbidities of obesity and the metabolic syndrome. Endocrine 2006;29:109e17. [15] Dello Russo M, Ahrens W, De Vriendt T, Marild S, Molnar D, Moreno LA, et al. Gestational weight gain and adiposity, fat distribution, metabolic profile, and blood pressure in offspring: the IDEFICS project. Int J Obes (Lond) 2013;37(7):914e9. [16] Falkner B, Gidding SS, Portman R, Rosner B. Blood pressure variability and classification of prehypertension and hypertension in adolescence. Pediatrics 2008;122:238e42. [17] Strambi M, Messa G, Berni S, Capitani S, Pammolli A, Iacoponi F, et al. Basal and post-ischemic vascular compliance in children/adolescents born small for gestational age. Pediatr Nephrol 2012;27:1541e6. [18] Redwine KM, Acosta AA, Poffenbarger T, Portman RJ, Samuels J. Development of hypertension in adolescents with pre-hypertension. J Pediatr 2012;160:98e103. [19] Genovesi S, Brambilla P, Giussani M, Galbiati S, Mastriani S, Pieruzzi F, et al. Insulin resistance, prehypertension, hypertension
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[26] Goldfield GS. Making access to TV contingent on physical activity: effects on liking and relative reinforcing value of TV and physical activity in overweight and obese children. J Behav Med 2012;35:1e7. [27] Horodynski MA, Baker S, Coleman G, Auld G, Lindau J. The healthy toddlers trial protocol: an intervention to reduce risk factors for childhood obesity in economically and educationally disadvantaged populations. BMC Public Health 2011;11:581e4. [28] Simsolo RB, Romo MM, Rabinovich L, Bonanno M,Grunfeld B. Family history of essential hypertension versus obesity as risk factors for hypertension in adolescents. Am J Hypertens 1999;12: 260e3. [29] Rodriguez-Moran M, Aradillas- Garcia C, Simental- Mendia LE, Monreal-Escalante E, de la Cruz Mendoza E, Davila Esueda ME. Family history of hypertension and cardiovascular risk factors in prepubertal children. Am J Hypertens 2010;23:299e304. [30] Spagnolo A, Giussani M, Ambruzzi A, Bianchetti S, Bianchetti M, Maringhini S, Matteucci MC, et al. Focus on prevention, diagnosis and treatment of hypertension in children and adolescents. It J Pediatr 2013;39:20e39.
Please cite this article in press as: Menghetti E, et al., Hypertension and obesity in Italian school children: The role of diet, lifestyle and family history, Nutrition, Metabolism & Cardiovascular Diseases (2015), http://dx.doi.org/10.1016/j.numecd.2015.02.009
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Nutrition, Metabolism & Cardiovascular Diseases journal homepage: www.elsevier.com/locate/nmcd
Hypertension and obesity in Italian school children: The role of diet, lifestyle and family history* E. Menghetti a, P. Strisciuglio b,*, A. Spagnolo c, M. Carletti d, G. Paciotti c, G. Muzzi e, M. Beltemacchi f, D. Concolino e, M. Strambi g, A. Rosano c a
Study Group on Hypertension, University “La Sapienza”, Rome, Italy Department of Pediatrics, University Federico II, Naples, Italy c ISFOL, Dipartimento Lavoro e Politiche Sociali, Rome, Italy d Human Physiology, University of Insubria, Italy e Department of Pediatrics, University “Magna Grecia”, Catanzaro, Italy f Department of Sport Medicine, Varese, Italy g Department of Molecular and Development Medicine, University of Siena, Italy b
Received 25 July 2014; received in revised form 6 February 2015; accepted 20 February 2015 Available online - - -
KEYWORDS Hypertension; Obesity; Students; Italy
Abstract Background and aims: In Italy, the prevalence of hypertension, obesity and overweight in paediatric patients has increased in the past years. The purpose of this study was to analyse the relationship between obesity and hypertension and related factors in Italian students. Methods and results: We studied 2007 healthy individuals between the ages of 6 and 17 years of age (998 males and 1009 females) attending schools in the cities of Varese (northern Italy), Rome (central Italy) and Catanzaro (southern Italy). The blood pressure, weight and height of the students were measured. We also assessed their daily intake of foods and the amount of physical activity they performed. A questionnaire was administered to the parents of the subjects to obtain information on the child’s medical history and family lifestyle. Of the students, 27.2% were overweight, and 6.6% were obese, with the highest percentages in southern Italy. A total of 6.2% of students had hypertension, and the region with the highest percentage was found to be northern Italy. Obese students had a risk of developing hypertension that was four times greater than those subjects who were of normal weight. Conclusion: Overweight and obese children/adolescents were more frequently found in southern Italy as opposed to northern and central Italy, and hypertensive children were more prevalent in the north. An unhealthy diet might explain the more widely spread obesity among children living in the south; an excess use of salt could explain the greater rate of hypertension found among children/adolescents living in the north. ª 2015 Elsevier B.V. All rights reserved.
Introduction The importance of measuring blood pressure (BP) in childhood and adolescence has been widely recognized
*
No honorarium, grant or other form of payment was given to any of the authors for the production of the manuscript. * Corresponding author. E-mail address: [email protected] (P. Strisciuglio).
[1,2]; elevated BP in children may be an early sign of essential (or primary) hypertension and childhood BP levels are predictive of adult levels [3,4]. In Italy, as in other economically developed countries, the prevalence of childhood hypertension has increased in the past years, from 2% to approximately 6% [5]. Even so, essential paediatric hypertension remains largely underdiagnosed and undertreated, and few studies have reported its prevalence and risk factors in children and adolescents. The prevalence of obesity and overweight children/adolescents has
http://dx.doi.org/10.1016/j.numecd.2015.02.009 0939-4753/ª 2015 Elsevier B.V. All rights reserved.
Please cite this article in press as: Menghetti E, et al., Hypertension and obesity in Italian school children: The role of diet, lifestyle and family history, Nutrition, Metabolism & Cardiovascular Diseases (2015), http://dx.doi.org/10.1016/j.numecd.2015.02.009
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also increased, now amounting to approximately 36% of Italian primary school children [6]. The aim of the present study was to assess the correlation between hypertension and obesity in a population of Italian students between 6 and 17 years of age located in three Italian cities representative of northern, central and southern Italy and to identify early those at risk of developing cardiovascular disease in adulthood. Methods A total of 2272 elementary-, middle- and high-school students in the cities of Varese, Rome and Catanzaro (located in northern, central and southern Italy, respectively) were enrolled in the study. They ranged in age from 6 to 17 years of age and were uniformly distributed among the three cities. Participation was voluntary. Informed, written consent was obtained from the parents of all participants and from the council board of the students’ schools. Two hundred twenty-seven students were excluded from the study because their parents refused to provide written consent (they did not want their children to be weighed and measured wearing only underwear). Another 38 children/adolescents were excluded because their measurements could not be fully taken. The final sample consisted of 2007 healthy students (998 males and 1009 females). Teams of medical researchers in the three zones all received specific training to standardize data-collection methodology, including the measurement of weight, height and blood pressure. All measurements were taken at the schools between 10:00 AM and 12:00 PM Body mass index (BMI), was used to determine whether a child was overweight or obese, according Cole et al.’s tables [7]. Weight and height were measured according to WHO recommendations, with the students in their underwear [8]. Body weight was measured in kilograms on a calibrated digital scale and height was measured in centimetres using a stadiometer. Blood pressure (BP) was measured using a mercury sphygmomanometer with the appropriate cuff for the subject’s upper arm size [9]. BP values were approximated to two mm Hg. Systolic BP was defined as the first Korotkoff sound (appearance of sounds), and diastolic BP was defined as the fifth Korotkoff sound (disappearance of sounds). Following these BP measurements, two other measurements were taken, 1 min apart from the other, using the method that we previously tested and used [10] on the right arm and with the student sitting down. BP was categorized according to the guidelines set out in the Fourth Report of the Task Force on Hypertension [11], using age and height percentiles. Normotension was defined when BP was under the 90th percentile, prehypertension was defined as a BP in the 90e95th percentile, and hypertension was defined as a BP greater than the 95th percentile.
E. Menghetti et al.
All children/adolescents that were found to have high blood pressure values or to be hypertensive or prehypertensive were rechecked after one week, and if the high pressure values persisted, they were rechecked a third time for a final measurement. Each student was also asked to fill out a detailed questionnaire to obtain information regarding diet, and the number of hours spent daily watching television and using a computer (number of hours per day), and performing physical activity and extracurricular sports (number of hours per week). We collected information on the frequency of breakfast consumption and the intake of the following food: fruit, cooked and fresh vegetables, bread and pasta, meat, fish, milk, cold cuts, potatoes, cheese, eggs, salty and sweet sneaks. All of these data were collected through a questionnaire completed by students and their parents and the answers were given using a scale ranging from 1 (seldom or never) to 4 (every day consumption). This method had been previously validated [12]. Children between 6 and 12 years of age filled out the questionnaire with the assistance of nurses. Two composite scores, the first on diet habits and the second on sedentary habits, were obtained using a linear combination of the values corresponding to the answers derived from a factor analysis (FA), and taking into account the coefficients of the first component 0.05. FA was used to analyse the relationship between variables (food or sedentary habits) because it is extremely useful in discriminating between individuals based on the characteristics included in this analysis [13]. The composite scores were then recalculated in quartiles; quartile values (1 Z unhealthy diet/sedentary; 2e4 Z healthy diet/not sedentary) were used in the logistic models. Parents were also asked to fill out a questionnaire regarding their own age, weight, and height, the presence of essential hypertension, and the birth weight and gestational age of their children. Pearson’s correlation coefficient was performed to assess the correlations between BMI, hypertension and the selected variable. A p-value equal or less than 0.05 was considered to be significant. A logistic model was used to assess the relationship between hypertension and obesity and between obesity, hypertension and selected factors (sedentary lifestyle, and an unhealthy diet) that were possibly related; the association was measured as odds ratios (OR) with 95% confidence intervals (95% CI), using subjects of normal weight as a reference, adjusting for sex and stratifying by the city in which the interviews were collected. The heterogeneity of the distribution of obesity and hypertension among the students by gender and geographic area was tested using a chi-square test, with a significance level set at 5%. Results The size of the sample allowed us to detect a risk of hypertension among obese children and adolescents with an
Please cite this article in press as: Menghetti E, et al., Hypertension and obesity in Italian school children: The role of diet, lifestyle and family history, Nutrition, Metabolism & Cardiovascular Diseases (2015), http://dx.doi.org/10.1016/j.numecd.2015.02.009
Hypertension and obesity in Italian school children
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odds ratio of 2.5. The expected prevalence of obesity was 5%, and the expected prevalence of hypertension among non-obese children was 6%, with a confidence level of 95% and a power of 80%. Of the participating students, 27.2% were overweight, with a higher percentage among males (30.5%) compared with females (25.0%), and in southern Italy (34.0%), compared with the northern (19.1%) and central regions (28.7%). Six percent (6.6%) were obese, with a higher percentage among males (7.9%) and in southern Italy (9.6%) (Table 1). The number and percentage of children/adolescents with hypertension and prehypertension by gender, age group and geographic area is reported in Table 2. Hypertension was more frequent among males (6.9%) and in northern Italy (10.0%). Prehypertension was also more frequent in northern Italy (12.1%) in both sexes. Regarding diet, the most commonly consumed foods were: pasta (94.8%), bread (83.1%), milk (75.4%), meat (72.9%), fruits (66.1%), vegetables (50.9%) and cold cuts (49.8%). The percentage of children adding salt to their meal was 41.6 in the north, 35.2 in the central region and 33,6 in the southern region (data not shown). Among male students, 79.9% reported that they ate breakfast regularly, compared with 74.6% of female students. The percentage was highest among 6- to 10-year-old children (83.5%) and tended to decrease with age (data not shown). Sports were practiced for more than 2 h per week by 43.6% of males and 29.3% of females. Per day, the mean time spent walking was 6e7 min in northern Italy, 10e11 min in southern Italy and 17e18 min in central Italy (data not shown). The coefficients derived from FA associated with food consumption and the habits of children are useful in discriminating between healthy/unhealthy food and healthy/unhealthy habits related to obesity and hypertension. Empirically, looking at the results of the FA represented on first two principal axes (Fig. 1), we can conclude that food with higher coefficients can be classified as healthy food (fruits: 0.532; salad: 0.530; and milk: 0.486), and food with negative coefficients can be classified as unhealthy food (sweet snacks: 0.330; and salted
snacks: 0.454). The frequency of breakfast consumption had a positive coefficient (0.498) that can be considered healthy; physical activities with positive coefficients (sport: 0.59) can be considered healthy, and those with negative coefficients are considered to be unhealthy (TV/ PC watching: 0,65). In the analysis of the association between obesity and an unhealthy diet and sedentary habits stratified by area, an unhealthy diet was still associated with obesity in the south (OR: 1.43; 95% CI: 1.04e1.96). Sedentary habits were associated with obesity in all areas, but more markedly in central Italy, although the association was still not statistically significant (Table 3). An unhealthy diet was associated with hypertension in southern Italy (OR: 1.43; 95% CI: 0.89e2.29) and was also associated with sedentary habits (OR: 1.34; 95% CI: 0.82e2.19), even if both associations were not statistically significant (Table 4). A strong relationship is present between obesity and hypertension in our sample, with 17.4% of obese children/ adolescents also presenting with hypertension. The risk of hypertension in obese children/adolescents (BP > 95th percentile) compared with normal-weight children/adolescents was much higher (OR Z 4.22; 95% C.I.: 2.56e6.93); and the risk for pre-hypertension (BP > 90th percentile) was similar (OR Z 4.20; 95% C.I. Z 2.82e6.26). The relationship between a child’s/adolescent’s obesity and that of their mother and father had an OR of 3.21 (95% CI: 1.92e5.34) and an OR of 3.25 (95% CI: 1.64e6.44), respectively. If both parents were obese, the OR for obese children was 10.64 (95% CI: 3.32e34.14). For hypertension, the OR was statistically significant only in the relationship between hypertension of the mother and the BP of children above the 90th percentile (OR: 1.96; 95% CI: 1.15e3.36). Finally we analysed the risk of hypertension among those who add salt to their food. The risk, adjusted for age and sex, was doubled among children living in the north (OR Z 2.0; 95% CI 1.05e3.85). Discussion
Table 1 Percentage of overweight and obese students by gender and geographic area. Area
Number of subjects Male Female Total Overweight Male Female Total Obese Male Female Total * Z p < 0.05.
North
Centre
South
Total
N 331 290 621 % 22.3* 15.6* 19.1 % 3.7 2.8 3.3
N 317 320 637 % 29.7 27.6 28.7 % 7.3 5.3 6.3
N 350 399 749 % 38.7* 29.8* 34.0 % 12.5* 7.1 9.6
N 998 1009 2007 % 30.5 25.0 27.2 % 7.9 5.5 6.6
We found a high incidence of obese and overweight children and adolescents. The incidence rate trended upward according to geography, moving from north to south; it was lowest in northern Italy, higher in central Italy and highest in southern Italy. Overall, the incidence rate was higher in males than in females, and 27.2% of our children/ adolescents (6e17 years) were overweight. The study of obese and overweight children is very important because these children often suffer from hypertension, hypercholesterolemia, hypertriglyceridemia and type 2 diabetes in addition to what is already in childhood called a “metabolic syndrome” [14]. The association between gestational weight gain, obesity and BP has been investigated and maternal gestational weight increase is an independent predictor of obesity in infancy, thus exposure to perinatal factors
Please cite this article in press as: Menghetti E, et al., Hypertension and obesity in Italian school children: The role of diet, lifestyle and family history, Nutrition, Metabolism & Cardiovascular Diseases (2015), http://dx.doi.org/10.1016/j.numecd.2015.02.009
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E. Menghetti et al.
Table 2 Number and percentage of students with hypertension, by gender, age-group and geographic area. Age
North Total number
Males 06e09 10e13 14e17 Total Females 06e09 10e13 14e17 Total
Centre Hyp
PreHy
%
%
Total number
South Hyp
PreHy
%
%
Total
Total number
Hyp
PreHy
%
%
1.8 4.1 19.1 7.1
2.7 4.7 22.5 8.6 2.6 6.6 8.6 5.5
107 81 143 331
3.7 17.3 10.5 10.0
3.7 17.3 12.6 10.9*
148 162 7 317
0.7 6.2 0.0 3.5*
1.4 0.6 14.3 1.3*
113 148 89 350
97 85 108 290
5.2 21.2 11,1 12.1*
7.2 7.1 13.0 9.3*
152 160 8 320
0.7 5.0 0.0 2.8
1.3 5.6 12.5 3.8
151 167 81 399
3.3 3.6 0.0 2.8*
Total number
Hyp
PreHy
%
%
368 391 239 998
1.9 7.7 13.4 6.9
2.4 5.6 16.3 7.0
400 412 197 1009
2.8 7.8 6.1 5.5
3.3 6.3 11.2 6.0
Hy Z Hypertension; PreHy Z PreHypertension; NHy Z No Hypertension. * Z p < 0.05.
should be taken into account for the early prevention of excessive weight gain and obesity [15]. We found that hypertension was more prevalent in northern Italy compared with central and southern Italy. Prehypertension [16e19] was found in a high percentage of children (7%), indicating that young people should be monitored to prevent them from gaining excess weight. Although these percentages are consistent with the nearly 6% reported in national and international case studies [20e22], they are much higher than the 1% reported in a study undertaken in Italy in 1981 [23]. In recent years, numerous studies focusing on obesity and hypertension have emphasized the great hazard posed by the significant increase in these pathological situations, in specific, the risk of a shortened life span [14]. Our results demonstrate the nutritional aspects involved in obesity. We found that the majority of the children who
participated in the study ate breakfast, especially children 6e10 years of age. The study also found that eating fruit and salad has a protective effect against hypertension. It is well known that salt consumption can affect BP [24]. In our study, salt consumption was higher in northern Italy than it was in other areas; and the risk of hypertension doubled among salt consumers. Finally, in our sample, children who performed little physical activity spent many afternoon hours in front of the television and/or computer. They also had an unhealthy diet, which is consistent with the results of other studies [25,26]. Our data also confirm the close link between obesity and hypertension and the link between obesity and a lack of daily physical activity. In our study, hypertension was associated not only with obesity but also with the addition of salt to food and a lack of physical activity. Finally, eating breakfast seems to be important, as does reducing salt
Figure 1 Representation of foods on first two principal axes on the basis of factor analysis. Distribution by the coefficient derived from the association between food consumption and habits of children.
Please cite this article in press as: Menghetti E, et al., Hypertension and obesity in Italian school children: The role of diet, lifestyle and family history, Nutrition, Metabolism & Cardiovascular Diseases (2015), http://dx.doi.org/10.1016/j.numecd.2015.02.009
Hypertension and obesity in Italian school children
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Table 3 Association between obesity vs diet and sedentary habit, adjusted for sex and stratified by area. Odds ratios (OR) and 95% confidence intervals (CI). Area
Factors
OR
95% CI Inf
Obesity vs diet North Sex (male reference) Unhealthy diet (healthy diet reference) Costant Center Sex (male reference) Unhealthy diet (healthy diet reference) Costant South Sex (male reference) Unhealthy diet (healthy diet reference) Costant Obesity vs sedentary habit North Sex (male reference) Sedentary (not sedentary reference) Costant Center Sex (male reference) Sedentary (not sedentary reference) Costant South Sex (male reference) Sedentary (not sedentary reference) Costant
.524 1.431 .223 .858 .807 .471 .646 1.432 .539 .455 1.087 .293 .915 1.362 .348 .656 1.132 .591
Sup
.312 .881 .856 2.393 .588 1.251 .553 1.178 .472 .885 1.043 1.965
.270 .767 .660 1.788 .642 1.304 .954 1.946 .482 .892 .827 1.551
consumption, favouring the Mediterranean diet. An obese child presents a clear risk of becoming hypertensive or prehypertensive. That risk is four times greater than of a child of normal weight; it is thus very important to prevent excess weight gain in childhood [27]. Taking into account family history of obesity and hypertension, children have a three-times greater risk of being obese if one parent is obese; and if both parents are obese, the risk is ten times greater compared with that of children with
Table 4 Association between hypertension vs diet and sedentary habit, adjusted for sex and stratified by area. Odds Ratios (OR) and 95% confidence intervals (CI). Area
Factors
OR
95% CI Inf
Hypertension vs diet North Sex (male reference) Unhealthy diet (healthy diet reference) Costant Center Sex (male reference) Unhealthy diet (healthy diet reference) Costant South Sex (male reference) Unhealthy diet (healthy diet reference) Costant Hypertension vs sedentary habit North Sex (male reference) Sedentary (not sedentary reference) Costant Center Sex (male reference) Sedentary (not sedentary reference) Costant South Sex (male reference) Sedentary (not sedentary reference) Costant
1.048 1.165 .298 .746 .946 .066 2.108 1.429 .072 .939 .835 .326 1.411 1.063 .044 .458 1.344 .150
Sup
.675 1.628 .751 1.808 .367 1.517 .461 1.939 1.329 3.343 .890 2.292
.599 1.473 .528 1.319 .648 3.072 .495 2.281 .282 .743 .822 2.195
parents of normal weight [28]. Children of mothers with hypertension have a two-times greater risk of having blood pressure values in the upper 90th percentile [29]. Our data in some ways confirm the strict relationship between food habits, hypertension and lifestyle and suggest that policy actions should be implemented nationally to reduce the trend of increased hypertension and obesity in Italian children given the higher risk of cardiovascular events in adulthood [30]. References [1] Flynn JT. Ambulatory blood pressure monitoring in children: imperfect yet essential. Pediatr Nephrol 2011;26:2089e94. [2] Zinner SH, Rosner B, Oh W, Kass EH. Significance of blood pressure in infancy. Hypertension 1985;3:411e6. [3] Daniels SR. Cardiovascular sequelae of childhood hypertension. Am J Hypertens 2002;15(2):61Se2S. [4] Thompson M, Duma T, Bougatsos C, Blazina I, Norris SL. Screening for hypertension in children and adolescents to prevent cardiovascular disease. Pediatrics 2013;131:490e4. [5] Menghetti E, Carletti M, Strisciuglio P, Spagnolo A. High percentage of obesity during childhood and adolescence and subsequent increases in childhood arterial hypertension. Minerva Pediatr 2010;2:133e7. [6] Spinelli A, Lamberti A, Baglio G, Andreozzi S, Galeone D, et al. Sistema di sorveglianza su alimentazione e attività fisica nei bambini della scuola primaria. Risultati 2008. Okkio alla salute, http://www.epicentro.iss.it/okkio alla salute/default.asp. ISSN 1123-3111, Rapporto ISTISAN 09/24. [7] Cole TJ, Bellizzi MC, Flegal KM, Dietz WH. Establishing a standard definition for child overweight and obesity worldwide: international survey. Br Med J 2000;320:1240e3. [8] World Health Organitation. Physical status: the use and interpretation of anthropometry. Geneva: WHO; 1995. Tech Rep Ser; 854. [9] Arafat M, Mattoo TK. Measurement of blood pressure in children; recommendations and perceptions of cuff selection pediatrics. Pediatrics 1999;104:e30. [10] Spagnolo A, Strisciuglio P, Menghetti E. Annual follow-up of children and adolescents in Southern Italy. Int J Pediatr Obes 2010; Suppl 1:67. [11] National High Blood Pressure Education Program Working Group on High Blood Pressure in Children and Adolescents. Fourth report on the diagnosis, evaluation and treatment of high blood pressure in children and adolescents. Pediatrics 2004;114(Suppl. 2): 555e76. [12] D’Addesa D, D’Addezio L, Martone D, Censi L, Scanu A, Cairella G, et al. Dietary intake and physical activity of normal weight and overweight/obese adolescents. Int J Ped 2010:2e9. http: //dx.doi.org/10.1155/2010/785649. ID78549. [13] Schulze MB, Hoffmann K, Kroke A, Boeing H. An approach to construct simplified measures of dietary patterns from exploratory factor analysis. Br J Nutr 2003;89(3):409e19. [14] Bray GA, Bellanger T. Epidemiology, trends, and morbidities of obesity and the metabolic syndrome. Endocrine 2006;29:109e17. [15] Dello Russo M, Ahrens W, De Vriendt T, Marild S, Molnar D, Moreno LA, et al. Gestational weight gain and adiposity, fat distribution, metabolic profile, and blood pressure in offspring: the IDEFICS project. Int J Obes (Lond) 2013;37(7):914e9. [16] Falkner B, Gidding SS, Portman R, Rosner B. Blood pressure variability and classification of prehypertension and hypertension in adolescence. Pediatrics 2008;122:238e42. [17] Strambi M, Messa G, Berni S, Capitani S, Pammolli A, Iacoponi F, et al. Basal and post-ischemic vascular compliance in children/adolescents born small for gestational age. Pediatr Nephrol 2012;27:1541e6. [18] Redwine KM, Acosta AA, Poffenbarger T, Portman RJ, Samuels J. Development of hypertension in adolescents with pre-hypertension. J Pediatr 2012;160:98e103. [19] Genovesi S, Brambilla P, Giussani M, Galbiati S, Mastriani S, Pieruzzi F, et al. Insulin resistance, prehypertension, hypertension
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Please cite this article in press as: Menghetti E, et al., Hypertension and obesity in Italian school children: The role of diet, lifestyle and family history, Nutrition, Metabolism & Cardiovascular Diseases (2015), http://dx.doi.org/10.1016/j.numecd.2015.02.009