Revista Adolescência e Saúde

Revista Oficial do Núcleo de Estudos da Saúde do Adolescente / UERJ

NESA Publicação oficial
ISSN: 2177-5281 (Online)

Vol. 14 nº 1 - Jan/Mar - 2017

Original Article Imprimir 

Páginas 65 a 73


Risk factors associated with the development of arterial hypertension in adolescents

Factores de riesgo asociados al desarrollo de presión arterial alta en adolescentes

Fatores de risco associados ao desenvolvimento de pressão arterial elevada em adolescentes

Autores: Sarita Müller1; Elisângela Colpo2; Franceliane Jobim Benedetti3

1. Bachelor's Degree in Nutrition, Centro Universitário Franciscano University Center (UNIFRA). Santa Maria, Rio Grande do Sul State, Brazil
2. PhD in Toxicological Biochemistry, Santa Maria Federal University (UFSM). Santa Maria, Rio Grande do Sul State, Brazil. Professor, Undergraduate Course in Nutrition, Centro Universitário Franciscano University Center (UNIFRA). Santa Maria, Rio Grande do Sul State, Brazil
3. PhD in Child and Adolescent Health , Rio Grande do Sul Federal University (UFRGS). Porto Alegre, Rio Grande do Sul State, Brazil. Professor, Undergraduate Course in Nutrition, Centro Universitário Franciscano University Center (UNIFRA). Santa Maria, Rio Grande do Sul State, Brazil

Sarita Müller
Rua Appel, nº 298, apto 402, Bom Fim
Santa Maria, RS, Brasil. CEP: 97015-030
sarita_muller@hotmail.com

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Keywords: Arterial pressure, cardiovascular diseases, anthropometry, adolescent.
Palabra Clave: Presión arterial, enfermedades cardiovasculares, antropometría, adolescente.
Descritores: Pressão arterial, doenças cardiovasculares, antropometria, adolescente.

Abstract:
OBJECTIVE: Verify the prevalence of risk factors associated to the development of elevated blood pressure in adolescents of public schools at Santa Maria - RS.
METHODS: Cross sectional study with the sample including students with age between 10 and 19 years of both genders. Were taken anthropometric measures, Body Mass Index (BMI) and waist circumference (WC), as well as data about practice of physical activity, food consumption, social demographic status and blood pressure(BP). Results are presented as median and standard deviation. Statistical analysis used Pearson's chi-square test, t -Student Test; Prevalence Ratio (PR) was verified by Poisson test. Values above p<0,05were considered statistically significant.
RESULTS: Were evaluated 576 adolescents with mean age of 16±1,29 years old. BMI, WC and gender demonstrate statistical difference between altered and normal BP. In the overweight adolescents was observed PR of 1,22 and the ones with elevated WC presented PR of 1,27 and elevated BP.
CONCLUSION: The altered BP in the adolescents presented significant prevalence ratio when associated to modifiable factors as overweight, abdominal adiposity, besides gender. So, strategies to control blood pressure are necessary.

Resumen:
OBJETIVO: Verificar la prevalencia de los factores de riesgo asociados al desarrollo de la presión arterial alta en adolescentes matriculados en escuelas públicas de la ciudad de Santa Maria - RS.
MÉTODOS: Estudio de carácter transversal con muestra constituida por estudiantes con edad entre 10 y 19 años de ambos sexos. Fueron realizados análisis antropométricos de Índice de Masa Corporal (IMC) y circunferencia de cintura (CC), como también preguntas ligadas a la práctica de actividad física, consumo alimenticio, datos socioeconómicos y presión arterial (PA). Los resultados están presentados en media y desvío estándar. Para asociación de las variables se utilizó el test de Chi-cuadrado; en la comparación fue empleado el test t-Student y la razón de prevalencia (RP) fue verificada por el test de Poisson. Valores de p<0,05 fueron considerados estadísticamente significativos.
RESULTADOS: Fueron evaluados 576 adolescentes con promedio de edad de 16±1,29 años. El IMC, CC y el sexo mostraron diferencia significativa entre la PA con y sin alteración. En los adolescentes con exceso de peso se observó la RP de 1,22 y los con a CC elevada presentaron RP de 1,27 y PA alterada.
CONCLUSIÓN: La PA alterada en los adolescentes presentó razón de prevalencia significativa asociada a factores modificables exceso de peso y de adiposidad abdominal, además del sexo. De esta forma, estrategias para control de peso son necesarias.

Resumo:
OBJETIVO: Verificar a prevalência dos fatores de risco associados ao desenvolvimento da pressão arterial elevada em adolescentes matriculados em escolas públicas da cidade de Santa Maria - RS.
MÉTODOS: Estudo de caráter transversal com amostra constituída por estudantes com idade entre 10 e 19 anos de ambos os sexos. Foram realizadas análises antropométricas do Índice de Massa Corporal (IMC) e circunferência da cintura (CC), como também questões ligadas à pratica de atividade física, consumo alimentar e dados socioeconômicos e pressão arterial (PA). Os resultados estão apresentados em média e desvio padrão. Para associação das variáveis utilizou-se o teste de qui-quadrado, na comparação foi empregado o teste t-Student e a razão de prevalência (RP) foi verificada pelo teste de Poisson. Valores de p<0,05 foram considerados estatisticamente significativos.
RESULTADOS: Foram avaliados 576 adolescentes com média de idade de 16±1,29 anos. O IMC, CC e o sexo mostraram diferença significativa entre a PA com e sem alteração. Nos adolescentes com excesso de peso observou-se a RP de 1,22 e os com a CC aumentada apresentaram RP de 1,27 e PA alterada.
CONCLUSÃO: A PA alterada nos adolescentes apresentou razão de prevalência significativa quando associadas aos fatores modificáveis excesso de peso e de adiposidade abdominal, além do sexo. Dessa forma, estratégias para controle de peso são necessárias.

INTRODUCTION

Cardiovascular diseases are among the main causes of death worldwide, and their spread through the developing countries sounds a warning on their potential impact for the less privileged classes1. Among cardiovascular diseases, systemic arterial hypertension (SAH) is the most common risk factor, linked to the upsurge in cardiovascular mortality rates1. Studies show that SAH among adults begins during childhood, stepping up concerns over routine assessments of blood pressure levels among children and adolescents2,3.

Many different factors may be related to these non-communicable chronic diseases, with overweight the most frequent among adolescents. Obesity, sedentary lifestyles and higher intakes of calorie-dense foods and salt also appear as factors leading to the appearance or worsening of cardiovascular diseases associated with comorbidities, such as metabolic syndrome, diabetes mellitus, dyslipidemias and systemic arterial hypertension2,3, in addition to coronary artery disease, which is the main cause of morbidity and mortality among adults5,6.

Anthropometric indicators such as the Body Mass Index (BMI) and Waist Circumference (WC) are widely used in epidemiological studies and clinical practice. Accurate, easy to perform and replicate, these methods are important tools for diagnosing overweight and obesity.

Consequently, it is stressed that the purpose of this study is to explore the prevalence of risk factors associated with the development of high blood pressure among adolescents enrolled at government schools in Santa Maria, Rio Grande do Sul State.


MATERIAlS AND METHODS

This cross-sectional research project was conducted with adolescent boys and girls enrolled at eight government-run secondary schools in the urban area of Santa Maria, Rio Grande do Sul State. Sampling was conducted at random by drawing classes in proportion to the number of pupils in the schools. The data were collected between March and August 2010 by the authors and pre-trained Nutrition Course students.

The data were obtained through completing individual questionnaires in classrooms. At this stage, a questionnaire was used classifying social and economic levels and physical activities, with a simplified section on eating habits and frequency. The anthropometric data were collected individually at a separate location, complying with standardized procedures for measuring Weight, Height and Waist Circumference.

This study encompassed boys and girls between 10 and 19 years old enrolled in the government school network, excluding those with physical and / or mental disabilities that would hamper the assessments and adversely affect the measurements.

The risk factors that were assessed as likely to lead to high blood pressure (BP) were: BMI, height for age, WC and food intake, together with tobacco and alcohol use. Another factor assessed was physical activity levels, which may help prevent the appearance of cardiovascular diseases.

The social and economic characteristics of the families of these adolescents were explored, using the Brazil Criteria Tool developed by the Brazilian Market Research Companies Association (ABEP)7, which generates scores based on the education levels of heads of families and ownership of household appliances, allowing the definition of economic class.

Anthropometric data (weight, height and WC) were double-checked, taking the mean value of the measurements. These youngsters were weighed on a Plenna® brand portable electronic digital scale with a capacity of up to 150kg, measuring their height with a portable Seca® brand stadiometer up to 220cm. These assessment tools were duly calibrated.

The nutritional status of these adolescents was classified in compliance with the BMI Z-Score z for age and height as proposed by the World Health Organization (2007)8. The collected data were analyzed through the Anthroplus program. For this study, a cut-off Z-Score of ≥1 was used to diagnose overweight.

The ideal height for age ratio was prepared8 using a -3 score for youngsters rated as very short for age, between ≥3 and <-2 for those rated as short for age and ≥-2 for those rated as appropriate height for age. The waist circumference was checked by a non-elastic tape measure placed around the smallest point pf the body between the bottom of the ribcage and the iliac crest. For classification, the >80 percentile was taken as indicating excess belly fat9.

Blood pressure was measured once with calibrated Omerom® 705 CP-II brand equipment, with the youngsters at rest. A cuff was used that was appropriate for the size of their arms, some 2 to 3 cm above the elbow pit, centralizing the rubber bag over the brachial artery. The width of the rubber bag must reach 40% of the arm circumference, with its length covering at least 80%. Blood pressure was classified as established by the Brazilian Pediatrics Society10, which considers BP < 90 percentile to be normal, based on the age and height percentiles. Consequently, adolescents with BP values higher than the 90 percentile were rated as having high blood pressure.

In terms of activity levels, the International Physical Activity Questionnaire (IPAQ)11 was used, which classifies respondents into three categories: insufficiently active, sufficiently active and very active.

In order to analyze food consumption, a simplified questionnaire was used to assess the consumption of cardiovascular risk marker food items among these adolescents, as proposed by Chiara and Sichieri12. This questionnaire lists nine food items (French fries, steak or pot roast, cookies, cake, high-fat milk, hamburger, cheese, butter or margarine and sausages) that are rated as coronary disease predictors, due to their potential aggressor factor status and chemical compositions. This questionnaire produces scores where eating properly is rated at totals of 100 or less; from 101 to 119, consumption is high; at 120 or more, it is rated as excessive, these scores are based on the foods listed in the simplified consumption questionnaire as described previously.

This research project was approved by the Research Ethics Committee (CEP) at the Rio Grande do Sul Federal University (UFRGS), under Protocol Nº 20009. Furthermore, all ethical aspects were complied with as set forth in Resolution Nº 196, issued by the National Health Council on October 10, 1996, which defines the guidelines and directives for research involving human beings. These aspects were taken into consideration, particularly in terms of underscoring ethical commitments to the subjects of this research project. All the respondents necessarily presented Deeds of Informed Consent signed and authorized by their parents or guardians.

The findings were presented in means and standard deviations. In order to analyze the qualitative variables, the chi-square test was used; the t-Student test was used for comparing the variables with the prevalence ratio (PR) checked through the robust Poisson test in order to analyze the bivariate variables. Values of p<0.05 were rated as statistically significant. The findings were analyzed through the Statistical Package for the Sciences software (SPSS) version 18.0.


RESULTS

A total of 576 adolescents were assessed with a mean age of 16±1.2 years and a majority (55.4) of the sample consisting of girls.

Table 1 presents the data for the association between risk factors leading to high blood pressure among adolescents enrolled in the government school network in Santa Maria, Rio Grande do Sul State. It was noted that the prevalence of high blood pressure (>90 percentile) reached 25.9% among these adolescents, and was higher among boys (15% vs. 11%, p<0.05).




With regard to the social and economic levels of these adolescents, the sample with the highest prevalence for unaltered blood pressure was found among those classified as B1 to B2, indicating mean family incomes between R$ 2,013.00 and R$ 3,479.00. Not smoking (96.0%) and not drinking alcohol (66.7%) were mentioned by a majority in this study (Table 1).

It is stressed that 74% of the adolescents with unaltered BP and 26% with alterations reported overconsumption of cardiovascular risk marker foods (Table 1).

The BMI, WC and gender variables showed a significant difference for developing higher blood pressure. There was no statistical difference between the following variables: social and economic levels, alcohol and tobacco consumption, food consumption and physical activities, in terms of BP alterations or not to (Table 1).

Table 2 presents the prevalence ratio (PR) with a 95% confidence interval (CI) for factors associated with higher blood pressure among adolescents, by gender. Taking physical activity levels into account, it was noted that youngsters who were sufficiently and very active posted PR <0.93 and <0.92 for higher blood pressure respectively (Table 2).




With regard to the BMI, a PR of 1.22 was found for higher BP among overweight adolescents: in other words, <90 percentile (Table 2). The mean BMI obtained for adolescents with unaltered BP was 21.2±3.2 kg/m² vs. 24.4±6.1 kg/m² for those with higher BP (p.<0.05).

Adolescents with increased WC presented a PR of 1.27 for altered blood pressure (Table 2). The mean WC found among youngsters with unaltered BP was 70.3±7.2 cm, rising to 78m3±12.5 cm for those with altered BP (p<0.05).


DISCUSSION

This research project found a prevalence ratio for high blood pressure with significant findings in terms of variables such as gender, BMI and WC. Boys posted the highest prevalence of altered BP, while overweight and not overweight pupils presented the highest prevalence of unaltered BP; adolescents with increased WC form the highest percentage in this study.

In a study conducted by Silva et al.13 that assessed youngsters between 11 and 13 years of age enrolled at government and private schools in Taguatinga, Federal District, the researchers found that boys posted higher blood pressure values than girls. Similar findings were noted in a longitudinal study which showed that boys presented a greater prevalence of a higher systolic and diastolic BP than girls. These results may be associated with time-related differences as biological changes occur, such as sexual maturation, testosterone production and body composition14.

In another research project conducted in Porto Alegre, Rio Grande do Sul State15 for a population belonging to social and economic classes similar to those explored in this study, it was noted that this was also not significantly associated with the presence of high BP levels. Similarly, Costa et al.16 found that 84.1% of assessed adolescents and their families lived on up to two monthly wages. In this income bracket, the youngsters did not present altered BP. In terms of this aspect, the authors suggested that this is due to limited access to food items with high energy density and high sodium content, thus keeping BP levels under control.

Another aspect mentioned as a risk factor for developing SAH is smoking and drinking alcohol. Freitas et al.17 indicated prevalences similar to those found in this study for smoking (5.4%) and higher for alcohol (63.6%) among youngsters between 15 and 17 years of age. These results lead to the hypothesis that this association was perhaps not detected due to reverse causality: in other words, the constraints inherent to cross-sectional studies where exposure and outcomes are collected simultaneously. It is nevertheless stressed that this is a young population, and the association among the factors is still not clear in the literature.

With regard to nutritional profiles, Katzmarzyk et al.5 showed a strong link between abdominal fat and the appearance of cardiovascular and metabolic diseases, which means that it is vital to analyze body fat distribution through the WC. In this research project, the prevalence of adolescents with excess belly fat, as reflected in the WC, with higher percentages of altered BP was lower than that found by Domingos et al.18 among adolescents between 10 and 17 years of age enrolled in the government school network in Cambira, Paraná State. In this study, the researchers noted that the odds of youngsters with abdominal obesity also presenting high blood pressure reached 284%, compared to pupils with normal WC measurements.

With regard to overweight, Monego and Jardim19 showed that in a sample of 3,388 children and adolescents between 7 and 15 years of age, high BMI was statistically associated with inadequate blood pressure levels. Nevertheless, it is stressed that in this study, overweight pupils posted a PR of 1.22 for altered BP, lower than the figure found in the study by Gomes and Alves20, which found a risk of 1.90 among overweight pupils and 3.10 among their obese peers, compared to youngsters with normal nutritional status.

As mentioned in this study, adolescents with excess belly fat presented an altered BP with a PR of 1.27. This may be related to body fat distribution as, although WC cannot discriminate between visceral fat and subcutaneous fat, research projects buttress the idea that people with high WC are more likely to have high blood pressure, diabetes, dyslipidemia for metabolic syndrome, adding information to that provided by the BMI5,18.

Another factor that is particularly noteworthy is information on physical activity levels, where youngsters ranked as sufficiently and very active may be less susceptible to rising blood pressure. However, when grouped by gender, lower susceptibility was statistically significant only for boys. However, there are also conflicting results, as in the study by Silva et al. 13 that assessed pupils enrolled in public and government schools, finding that the odds of developing SAH was almost twice as high among adolescents rated as either inactive or insufficiently active.

Food consumption showed no significant association with high blood pressure risks among these adolescents, which is aligned with the results of another Brazilian study20. The fact that food consumption did not produce any significant repercussions on the BP of these youngsters may be justified to some extent by the reverse causality of cross-sectional studies, in addition to constraints on the use of the simplified questionnaire, as this has not yet been validated and did not offer the option of additional sodium consumption. It must also be recalled that the effects of protective nutrients were not assessed, which may confound the analysis.


CONCLUSION

In brief, it was noted that overweight teens posted a higher prevalence of unaltered blood pressure. Among pupils with altered BP, the mean BMI was higher than for those whose BP remained unaltered. Those with larger WC also presented a higher prevalence of altered blood pressure. The mean WC calculated for those with altered BP was higher than those whose BP remained unaltered. It was noted that a low percentage of youngsters with altered BP usually ate excessive amounts of food.

These results are a matter of much concern in today´s world, underscoring the importance of systematic BP monitoring, as rising consumption of high-calorie foods that are rich in fat and high in sodium, with fewer physical activities and rising obesity, among other factors, all underpins the likelihood of developing problems related to cardiovascular diseases. Bearing in mind that the risk factors addressed in this study are open to modification, except for gender, it is suggested that weight control strategies should be implemented through a suitable diet with reasonable amounts of physical activity, thus encouraging youngsters to play active roles in modifying their own behaviors.


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