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High Blood Pressure in Adolescents of Curitiba: Prevalence and Associated Factors

Abstract

Background:

Arterial hypertension is a major public health problem and has increased considerably in young individuals in past years. Thus, identifying factors associated with this condition is important to guide intervention strategies in this population.

Objective:

To determine high blood pressure prevalence and its associated factors in adolescents.

Methods:

A random sample of 1,242 students enrolled in public schools of the city of Curitiba (PR) was selected. Self-administered questionnaires provided family history of hypertension, daily energy expenditure, smoking habit, daily fat intake, and socioeconomic status. Waist circumference was measured following standardized procedures, and blood pressure was measured with appropriate cuffs in 2 consecutive days to confirm high blood pressure. Relative frequency and confidence interval (95%CI) indicated high blood pressure prevalence. Bivariate and multivariate analyses assessed the association of risk factors with high blood pressure.

Results:

The high blood pressure prevalence was 18.2% (95%CI 15.2-21.6). Individuals whose both parents had hypertension [odds ratio (OR), 2.22; 95%CI 1.28-3.85] and those with high waist circumference (OR, 2.1; 95%CI 1.34-3.28) had higher chances to develop high blood pressure.

Conclusion:

Positive family history of hypertension and high waist circumference were associated with high blood pressure in adolescents. These factors are important to guide future interventions in this population.

Keywords:
Arterial Blood Pressure; Hypertension/genetics; Waist Circumference; Risk Factors; Adolescent

Resumo

Fundamento:

A hipertensão arterial é um grave problema de saúde pública e, nos últimos anos, tem aumentado consideravelmente em jovens. A identificação de fatores associados com essa condição é importante para guiar estratégias de intervenção nessa população.

Objetivo:

Determinar a prevalência e os fatores associados com a pressão arterial alterada em adolescentes.

Métodos:

Foi selecionada amostra probabilística de 1.242 adolescentes da rede pública de ensino de Curitiba (PR). Por meio de questionários, foram obtidos o histórico familiar de hipertensão, o gasto energético diário, informações sobre tabagismo, o consumo diário de gorduras e a classificação econômica. A circunferência da cintura foi medida por procedimentos padronizados. A pressão arterial foi aferida com manguitos adequados em 2 dias consecutivos para a confirmação da pressão arterial alterada. Frequências relativas e intervalos de confiança (IC95%) indicaram a prevalência de pressão arterial alterada. Regressões logística bivariadas e multivariadas testaram a associação dos fatores de risco com a pressão arterial alterada.

Resultados:

A prevalência de pressão arterial alterada foi de 18,2% (IC95% 15,2-21,6). Mais chances de pressão arterial alterada foram encontradas nos indivíduos que possuíam ambos os pais com hipertensão arterial [odds ratio (OR), 2,22; IC95% 1,28-3,85] e naqueles com a circunferência da cintura aumentada (OR, 2,1; IC95% 1,34-3,28).

Conclusão:

O histórico familiar positivo de hipertensão arterial e a circunferência da cintura aumentada estiveram associados a pressão arterial alterada em adolescentes. Esses fatores são importantes para guiar intervenções futuras nessa população.

Palavras-chave:
Pressão Arterial; Hipertensão / genética; Circunferência da Cintura; Fatores de Risco; Adolescente

Introduction

Arterial hypertension accounts for approximately 54% of cerebrovascular diseases and 47% of ischemic heart diseases worldwide, causing approximately 13% of all deaths per year, being, thus, a serious public health problem.11 Williams B. The year in hypertension. J Am Coll Cardiol. 2010;55(1):66-73.,22 Organização Mundial de Saúde. (OMS). Global health risks: mortality and burden of disease attributable to selected major risks. Geneva; 2009.

Although the major repercussions of arterial hypertension do not manifest in young individuals, it is suggested that children and adolescents with high blood pressure (prehypertension and arterial hypertension) are more likely to become hypertensive adults.33 Chen W, Srinivasan SR, Ruan L, Mei H, Berenson GS. Adult hypertension is associated with blood pressure variability in childhood in blacks and whites: the Bogalusa Heart Study. Am J Hypertens. 2011;24(1):77-82. That is worrying, because the prevalence of high blood pressure in young individuals has increased considerably in past decades.44 National High Blood Pressure Education Program Working Group on High Blood Pressure in Children and Adolescents. The Fourth Report on the Diagnosis, Evaluation, and Treatment of High Blood Pressure in Children and Adolescents. Pediatrics. 2004;114(2 Suppl 4th Report):555-76.,55 Din-dzietham R, Liu Y, Bielo MV, Shamsa F. High blood pressure trends in children and adolescents in national surveys, 1963 to 2002. Circulation. 2007;116(13):1488-96.

In Brazil, a systematic review has identified 21 studies aimed at identifying high blood pressure in the Brazilian young population; however, a large part of those studies has not used representative population samples, in addition to having failed to classify blood pressure and to use proper assessment criteria.66 Magalhães MG, Oliveira LM, Christofaro DG, Ritti-dias RM. Prevalence of high blood pressure in Brazilian adolescents and quality of the employed methodological procedures: systematic review. Rev Bras Epidemiol. 2013;16(4):849-59. Those limitations can have important implications in estimating high blood pressure prevalence and in defining the factors associated with it.

Nevertheless, it is important to identify possible factors associated with high blood pressure in Brazilian adolescents, such as family history of arterial hypertension,77 Fuentes RM, Notkola IL, Shemeikka S, Tuomilehto J, Nissinen A. Familial aggregation of blood pressure: a population-based family study in eastern Finland. J Hum Hypertens. 2000;14(7):441-5.

8 Almeida FA, Yoshizumi AM, Mota AC, Fernandes AP, Gushi AC, Nakamoto AY. Blood pressure distribution and hypertension prevalence in high school students of Sorocaba, SP. J Bras Nefrol. 2003;25(4):179-86.
-99 de Araújo TL, de Lopes MV, Cavalcante TF, Guedes NG, Moreira RP, Chaves ES, et al. [Analysis of risk indicators for the arterial hypertension in children and teenagers]. Rev Esc Enferm USP. 2008;42(1):120-6. sex,1010 Gomes Bda M, Alves JG. [Prevalence of high blood pressure and associated factors in students from public schools in Greater Metropolitan Recife, Pernambuco State, Brazil, 2006]. Cad Saúde Pública. 2009;25(2):375-81.

11 Romanzini M, Reichert FF, Lopes Ada S, Petroski EL, Farias Júnior JC. [Prevalence of cardiovascular risk factors in adolescents]. Cad Saúde Pública. 2008;24(11):2573-81.

12 Christofaro DG, Ritti-Dias RM, Fernandes RA, Polito MD, Andrade SM, Cardoso JR, et al. High blood pressure detection in adolescents by clustering overall and abdominal adiposity markers. Arq Bras Cardiol. 2011;96(6):465-70.
-1313 Pinto SL, Silva Rde C, Priore SE, Assis AM, Pinto Ede J. [Prevalence of pre-hypertension and arterial hypertension and evaluation of associated factors in children and adolescents in public schools in Salvador, Bahia State, Brazil]. Cad Saúde Pública. 2011;27(6):1065-76. age,1414 Kelishadi, R, Sadri G, Tavasoli AK, Kahbazi M, Roohafza HR, Sadeghi M, et al Cumulative prevalence of risk factors for atherosclerotic cardiovascular diseases in Iranian adolescents. J Pediatr (Rio J). 2005;81(6):447-53. socioeconomic aspects,1313 Pinto SL, Silva Rde C, Priore SE, Assis AM, Pinto Ede J. [Prevalence of pre-hypertension and arterial hypertension and evaluation of associated factors in children and adolescents in public schools in Salvador, Bahia State, Brazil]. Cad Saúde Pública. 2011;27(6):1065-76.,1515 Constanzi CB, Halpern R, Rech RR, Bergmann ML, Alli LR, Mattos AP Associated factors in high blood pressure among schoolchildren in a middle size city, southern Brazil. J Pediatr (Rio J). 2009;85(4):335-40.,1616 Silva KS, Farias Júnior JC. Risk factors associated with high blood pressure in adolescents. Rev Bras Med Esporte. 2007;13(4):237-40. fat intake,1717 Guedes DP, Guedes JE, Barbosa DS, Oliveira JA, Stanganelli LC. [Cardiovascular risk factors in adolescents: biological and behavioral indicators]. Arq Bras Cardiol. 2006;86(6):439-50.,1818 Campos W, Stabelini Neto A, Bozza R, Ulbrich AZ, Bertin RL, Mascarenhas LP, et al. [Physical activity, lipid consumption and risk factors for atherosclerosis in adolescents]. Arq Bras Cardiol. 2010;94(5):601-7. energy expenditure,1010 Gomes Bda M, Alves JG. [Prevalence of high blood pressure and associated factors in students from public schools in Greater Metropolitan Recife, Pernambuco State, Brazil, 2006]. Cad Saúde Pública. 2009;25(2):375-81.,1313 Pinto SL, Silva Rde C, Priore SE, Assis AM, Pinto Ede J. [Prevalence of pre-hypertension and arterial hypertension and evaluation of associated factors in children and adolescents in public schools in Salvador, Bahia State, Brazil]. Cad Saúde Pública. 2011;27(6):1065-76.,1616 Silva KS, Farias Júnior JC. Risk factors associated with high blood pressure in adolescents. Rev Bras Med Esporte. 2007;13(4):237-40. smoking,1010 Gomes Bda M, Alves JG. [Prevalence of high blood pressure and associated factors in students from public schools in Greater Metropolitan Recife, Pernambuco State, Brazil, 2006]. Cad Saúde Pública. 2009;25(2):375-81.,1616 Silva KS, Farias Júnior JC. Risk factors associated with high blood pressure in adolescents. Rev Bras Med Esporte. 2007;13(4):237-40. abdominal obesity,1919 Guimarães IC, Almeida AM, Santos AS, Barbosa DB, Guimarães AC. Blood pressure: effect of body mass index and of waist circumference on adolescents. Arq Bras Cardiol. 2008;90(6):426-32.,2020 Bozza R, Stabelini Neto A, Ulbrich AZ, Vasconcelos IQ, Mascarenhas LP, Brito LMS, et al Waist circumference, body mass index and cardiovascular risk factors in adolescence. Rev Bras Cineantropom Desempenho Hum. 2009;11(3):286-91. and cardiorespiratory fitness.2121 Stabelini Neto A, Bozza R, Ulbrich AZ, Vasconcelos IQ, Mascarenhas LP, Boguszewski MC, et al. [Atherosclerotic risk factors associated with cardiorespiratory fitness and BMI in adolescents]. Arq Bras Endocrinol Metabol. 2008;52(6):1024-30.

The identification of population subgroups at risk for developing high blood pressure can better direct prevention strategies in the Brazilian young population.99 de Araújo TL, de Lopes MV, Cavalcante TF, Guedes NG, Moreira RP, Chaves ES, et al. [Analysis of risk indicators for the arterial hypertension in children and teenagers]. Rev Esc Enferm USP. 2008;42(1):120-6.,2222 Sociedade Brasileira de Cardiologia; Sociedade Brasileira de Hipertensão; Sociedade Brasileira de Nefrologia. [VI Brazilian Guidelines on Hypertension]. Arq Bras Cardiol. 2010;95(1 Suppl):1-51. Erratum in: Arq Bras Cardiol. 2010;95(4):553. Thus, the present study aimed at determining the prevalence of high blood pressure and its associated factors in a representative sample of adolescents of the public school system.

Methods

This cross-sectional study was performed from August 2010 to June 2011 with adolescents enrolled in public middle and high schools of the city of Curitiba, Paraná state.

To estimate sample size, the following parameters were considered: (i) population of 115,524 adolescents; (ii) confidence level of 95%; (iii) sampling error of 2%; (iv) arterial hypertension prevalence of 7.4%,1616 Silva KS, Farias Júnior JC. Risk factors associated with high blood pressure in adolescents. Rev Bras Med Esporte. 2007;13(4):237-40. adding up to a minimum sample of 982 adolescents. A design effect of 1.5 was added to correct the error related to multistage sample selection, as was a 30% margin for possible losses and refusals. Therefore, the total sample was estimated in 1,276 adolescents.

The probabilistic sample was selected by use of multiple stages. In the first stage, all public middle and high schools in the city of Curitiba were listed and stratified according to the nine administrative regions of the city. In the second stage, five schools were randomly selected from each administrative region, and, in the third stage, a simple random selection of one to three classes at each school was performed. The adolescents received an assent term, and their parents, a consent term, explaining the research objectives and procedures, to be completed and signed.

The family history of arterial hypertension was obtained with a questionnaire sent to the adolescent's parents or guardians, which indicated if the biological father and/or mother had arterial hypertension.

The waist circumference was measured at a level midway between the last costal arch and the iliac crest, following standard procedures.2323 Lopes MA, Martins MO. Perímetros. In: Petroski EL. Antropometria: técnicas e padronizações. Porto Alegre: Palotti; 1999. p. 69-86. The increased value for each sex and age group was determined according to the proposal by Freedman et al.2424 Freedman DS, Serdula MK, Srinivasan SR, Berenson GS. Relation of circumferences and skinfold thicknesses to lipid and insulin concentrations in children and adolescents: the Bogalusa Heart Study. Am J Clin Nutr. 1999;69(2):308-17. as ≥ 90th percentile.

The daily energy expenditure (kcal/kg/day) was obtained from a 3-day activity record developed by Bouchard et al.,2525 Bouchard CA, Tremblay A, Leblanc C, Lortie G, Savard R, Thériault G. A method to assess energy expenditure in children and adults. Am J Clin Nutr. 1983;37(3):461-7. the mean value obtained being considered. The individuals were classified into sample quartiles according to sex and age group.

The cardiorespiratory fitness was assessed by using the shuttle run test proposed by Léger et al.2626 Léger LA, Mercier D, Gadoury C, Lambert J. The multistage 20 metre shuttle run test for aerobic fitness. J Sports Sci. 1988;6(2):93-10. The individuals were classified into sample quartiles according to sex and age group.

To define smoking, the adolescents completed the Youth Risk Behavior Survey Questionnaire, translated and validated by Guedes and Lopes.2727 Guedes DP, Lopes CC. Validation of the Brazilian version of the 2007 Youth Risk Behavior Survey. Rev Saude Publica. 2010;44(5):840-50. That questionnaire inquires how many days, in the preceding 30 days, cigarettes were smoked. The individuals were classified into three categories as follows: cigarettes smoked 10 to 30 days; cigarettes smoked 1 to 9 days; and no cigarette smoked in the preceding 30 days.

The total fat intake was obtained by completing a food frequency questionnaire developed for the Brazilian population by Sichieri and Everhart.2828 Sichieri R, Everhart JE. Validity of a Brazilian food frequency questionnaire against dietary recalls and estimated energy intake. Nutr Res. 1998;18(10):1649-59. To maintain data quality, the cases with energy expenditure greater than 6,000 kcal or lower than 500 kcal were excluded.2929 Andrade RG, Pereira RA, Sichieri R. [Food intake in overweight and normal-weight adolescents in the city of Rio de Janeiro]. Cad Saúde Pública. 2003;19(5):1485-95. According to the American Heart Association, in a proper food intake, total fat intake should be < 30%.3030 Lichtenstein AH, Appel LJ, Brands M, Carnethon M, Daniels S, Franch HA, et al; American Heart Association Nutrition Committee. Diet and lifestyle recommendations revision 2006: a scientific statement from the American Heart Association Nutrition Committee. Circulation. 2006;114(1):82-96. Erratum in: Circulation. 2006;114(23):e629. Circulation. 2006;114(1):e27.

The socioeconomic status was classified according to the criteria established by the Brazilian Association of Research Companies.3131 Associação Brasileira de Empresas de Pesquisa. Critério de classificação econômica Brasil 2008. [Acesso em 2009 jun 8]. Disponível em: http://www.abep.org
http://www.abep.org...
In the present study, the participants were classified into the following four socioeconomic levels: I, lowest socioeconomic level (classes D and E); II, classes C1 and C2; III, classes B1 and B2; and IV, highest socioeconomic level (classes A1 and A2).

Blood pressure was measured by using the auscultatory method, following the parameters established in the fourth report of the National High Blood Pressure Education Program .44 National High Blood Pressure Education Program Working Group on High Blood Pressure in Children and Adolescents. The Fourth Report on the Diagnosis, Evaluation, and Treatment of High Blood Pressure in Children and Adolescents. Pediatrics. 2004;114(2 Suppl 4th Report):555-76. Before that, arm circumference was measured to enable the choice of the cuff size [child (16 - 22 cm), small adult (23 - 26 cm) and adult (27 - 34 cm)].44 National High Blood Pressure Education Program Working Group on High Blood Pressure in Children and Adolescents. The Fourth Report on the Diagnosis, Evaluation, and Treatment of High Blood Pressure in Children and Adolescents. Pediatrics. 2004;114(2 Suppl 4th Report):555-76. In addition, the adolescents were asked about having already had their blood pressure assessed before.

Two blood pressure readings were taken at a 5-minute interval, the mean value being considered in this study. If the readings differed more than 2 mm Hg, the protocol would be repeated.44 National High Blood Pressure Education Program Working Group on High Blood Pressure in Children and Adolescents. The Fourth Report on the Diagnosis, Evaluation, and Treatment of High Blood Pressure in Children and Adolescents. Pediatrics. 2004;114(2 Suppl 4th Report):555-76.

In accordance with The Fourth Report on the Diagnosis, Evaluation, and Treatment of High Blood Pressure in Children and Adolescents ,44 National High Blood Pressure Education Program Working Group on High Blood Pressure in Children and Adolescents. The Fourth Report on the Diagnosis, Evaluation, and Treatment of High Blood Pressure in Children and Adolescents. Pediatrics. 2004;114(2 Suppl 4th Report):555-76. the cutoff values used, according to sex, age and height percentile, were as follows: arterial hypertension - systolic blood pressure (SBP) and/or diastolic blood pressure (DBP) ≥ 95th percentile; prehypertension - SBP and DBP values < 95th percentile and ≥ 90th percentile. Individuals with blood pressure values > 120/80 mm Hg were considered prehypertensive.44 National High Blood Pressure Education Program Working Group on High Blood Pressure in Children and Adolescents. The Fourth Report on the Diagnosis, Evaluation, and Treatment of High Blood Pressure in Children and Adolescents. Pediatrics. 2004;114(2 Suppl 4th Report):555-76.

Adolescents classified as prehypertensive or hypertensive were reassessed at a subsequent visit on the day following the first assessment, in which case the second blood pressure measurement was considered for the analysis. At both the first and subsequent visit, blood pressure was measured by only one trained professional to prevent interobserver disagreement.

Continuous data were described by use of measures of central tendency and dispersion for both sexes. Continuous data were compared between sexes by use of independent t and Mann-Whitney U tests, based on normality of data.

Categorical variables were described by use of relative frequency distribution and its respective 95% confidence interval (95%CI). The chi-square test for heterogeneity was used to compare the differences in the prevalences of prehypertension, arterial hypertension and high blood pressure (prehypertension and arterial hypertension) between sexes, and to compare the high blood pressure prevalences in the first and second visits.

The association between independent variables and high blood pressure was assessed by use of bivariate and multivariate analysis (logistic regression). The variables with a p value < 0.25 on bivariate analysis were selected for the multivariate model. The magnitude of the association between the independent variables and high blood pressure was expressed as odds ratio (OR) and its respective 95%CI. The prevalence and association analyses were corrected with the complex sample design, using the 'complex sample' command of the Statistical Package for the Social Science (SPSS) software, version 17.0. The significance level adopted for all analyses was p < 0.05.

The methodology of this study was approved by the Research Ethics Committee of the Health Science Sector of the Paraná Federal University (UFPR), and abided by the ethical guidelines established by the 196/96 Resolution of the Brazilian National Health Council (CAAE 04414712.3.0000.0102) on the 25th October, 2012.

Results

Data of 1,812 adolescents were collected. Of those, 570 adolescents meeting at least one exclusion criterion were excluded from the final analysis as follows: 28 individuals were at least 18 years old; 22 were on anti-hypertensive drugs; 84 female adolescents were on oral contraceptives and one was pregnant; 172 adolescents did not deliver the family history of arterial hypertension of both parents; 239 completed the questionnaires incorrectly; 46 underwent neither anthropometric assessments nor the cardiorespiratory fitness test; and 70 individuals did not undergo blood pressure reassessment.

Therefore, this study's final sample comprised 1,242 adolescents aged between 11 and 17 years, 646 of whom (52.01%) were females. The age group distribution was as follows: 11-12 years, 363 individuals (56.2% females and 43.8% males); 13-15 years, 697 individuals (52.5% females and 47.5% males); and 16-17 years, 182 individuals (41.8% females and 58.2% males). Of the total sample, 34.06% had never undergone blood pressure assessment.

Table 1 shows the sample's continuous variables with their central tendency and dispersion.

Table 1
Central tendency and dispersion values of the variables according to sex in adolescents

When comparing continuous data between sexes, all variables, except for DBP, were significantly higher in male individuals (p < 0.01).

Table 2 shows the prevalences of arterial hypertension family history, smoking, total fat intake and socioeconomic level for both sexes.

Table 2
Prevalence (%) and confidence interval (95%CI) of the categorical variables in adolescents according to sex

Table 3 shows the prevalences of prehypertension and arterial hypertension on the two visits. Regarding the general prevalence of high blood pressure (prehypertension and arterial hypertension), a significant difference (X2 = 523.1; p < 0.01) between the first (33.0%; 95%CI 29.1-37.1) and second visit (18.2%; 95%CI 15.2-21.6) was observed.

Table 3
Prevalence (%) and confidence interval (95%CI) for prehypertension and arterial hypertension on both assessment visits of adolescents according to sex

Considering only the values of the second visit, no significant difference between sexes was observed in the prevalences of prehypertension (X2 = 0.01; p = 0.91) and arterial hypertension (X2 = 2.11; p = 0.15).

At the second visit, the high blood pressure prevalence was 17.5% (95%CI 14.1-21.4) in the male sex, and 18.8% (95%CI 14.7-23.8) in the female sex, showing no significant difference between sexes (X2 = 1.17; p = 0.28).

Table 4 shows the bivariate and multivariate associations of the variables analyzed with high blood pressure in adolescents. The multivariate model was adjusted to the variables with p < 0.25 on bivariate analysis [family history of arterial hypertension, waist circumference, maximum oxygen consumption (VO2max), total fat intake, and socioeconomic level]. On multivariate model, high blood pressure associated (p < 0.05) with family history of arterial hypertension, waist circumference and total fat intake.

Table 4
Factors associated with high blood pressure in adolescents

Discussion

When prehypertension and arterial hypertension were considered together, the prevalences observed in the present study were higher than those reported in an international study by Duncan et al.3232 Duncan GE, Li SM, Zhou XH. Prevalence and trends of a metabolic syndrome phenotype among U.S. adolescents, 1999-2000. Diabets Care. 2004;27(10):2438-43.(8%) and those reported in the Brazilian studies by Vieira et al.3333 Vieira MA, Carmona DP, Anjos LA, Souza T, Espinosa MM, Ribeiro RL, et al. Pressão arterial de crianças e adolescentes de escolas públicas de Cuiabá, Mato Grosso. Acta Paul Enferm. 2009;22(1):473-5. and Pinto et al.1313 Pinto SL, Silva Rde C, Priore SE, Assis AM, Pinto Ede J. [Prevalence of pre-hypertension and arterial hypertension and evaluation of associated factors in children and adolescents in public schools in Salvador, Bahia State, Brazil]. Cad Saúde Pública. 2011;27(6):1065-76. (11.2% and 4.8%, respectively).

In Brazil, Romanzini et al.1111 Romanzini M, Reichert FF, Lopes Ada S, Petroski EL, Farias Júnior JC. [Prevalence of cardiovascular risk factors in adolescents]. Cad Saúde Pública. 2008;24(11):2573-81. have shown a similar prevalence (18.6%) of high blood pressure, while another study conducted in the city of São Mateus do Sul, Paraná state, has shown a higher high blood pressure prevalence than that in the present study (24.1% for males and 25.6% for females).2020 Bozza R, Stabelini Neto A, Ulbrich AZ, Vasconcelos IQ, Mascarenhas LP, Brito LMS, et al Waist circumference, body mass index and cardiovascular risk factors in adolescence. Rev Bras Cineantropom Desempenho Hum. 2009;11(3):286-91.

Those studies have assessed blood pressure only at one visit. However, as shown in the present study, blood pressure reassessment at a subsequent visit is very important, because blood pressure levels can change from one visit to the other, tending to decrease.

That reduction in blood pressure levels might be due to a decrease in anxiety and familiarization of adolescents with the measuring procedures from the second visit on.44 National High Blood Pressure Education Program Working Group on High Blood Pressure in Children and Adolescents. The Fourth Report on the Diagnosis, Evaluation, and Treatment of High Blood Pressure in Children and Adolescents. Pediatrics. 2004;114(2 Suppl 4th Report):555-76. In addition, as approximately 34% of the adolescents in this study had never undergone blood pressure assessment, they could be anxious or even frightened, which could yield increased blood pressure levels. Thus, individuals with high blood pressure levels at the first visit might feel more comfortable with the procedures and measurers from the second visit on.

Regarding the associations, individuals whose both parents were hypertensive had a higher chance to develop high blood pressure. This is in accordance with another study, in which individuals with a history of arterial hypertension had more blood pressure values exceeding the normal limits.88 Almeida FA, Yoshizumi AM, Mota AC, Fernandes AP, Gushi AC, Nakamoto AY. Blood pressure distribution and hypertension prevalence in high school students of Sorocaba, SP. J Bras Nefrol. 2003;25(4):179-86. It is worth noting that inherited factors contribute to the development of high blood pressure in adolescents, and, in addition, the adolescent's family setting is shared in regard to behavioral factors,77 Fuentes RM, Notkola IL, Shemeikka S, Tuomilehto J, Nissinen A. Familial aggregation of blood pressure: a population-based family study in eastern Finland. J Hum Hypertens. 2000;14(7):441-5.,99 de Araújo TL, de Lopes MV, Cavalcante TF, Guedes NG, Moreira RP, Chaves ES, et al. [Analysis of risk indicators for the arterial hypertension in children and teenagers]. Rev Esc Enferm USP. 2008;42(1):120-6. which can contribute to increase blood pressure levels.

Regarding the association of waist circumference and high blood pressure identified in this study, other studies have shown the same tendency.1919 Guimarães IC, Almeida AM, Santos AS, Barbosa DB, Guimarães AC. Blood pressure: effect of body mass index and of waist circumference on adolescents. Arq Bras Cardiol. 2008;90(6):426-32.,2020 Bozza R, Stabelini Neto A, Ulbrich AZ, Vasconcelos IQ, Mascarenhas LP, Brito LMS, et al Waist circumference, body mass index and cardiovascular risk factors in adolescence. Rev Bras Cineantropom Desempenho Hum. 2009;11(3):286-91. They have evidenced that the 'waist circumference' measure can determine the fat distribution in the abdominal region, being related to metabolic risk, in adults, children and adolescents.2020 Bozza R, Stabelini Neto A, Ulbrich AZ, Vasconcelos IQ, Mascarenhas LP, Brito LMS, et al Waist circumference, body mass index and cardiovascular risk factors in adolescence. Rev Bras Cineantropom Desempenho Hum. 2009;11(3):286-91.,3434 Janssen I, Katzmarzyk PT, Ross R. Waist circumference and not body mass index explains obesity-related health risk. Am J Clin Nutr. 2004;79(3):379-84.

Considering the total fat intake, individuals with an increased fat consumption (≥ 30%) have shown a smaller chance to develop high blood pressure, and, thus, total fat intake is a protective factor against high blood pressure.

Contrary to the present study, Guedes et al.1717 Guedes DP, Guedes JE, Barbosa DS, Oliveira JA, Stanganelli LC. [Cardiovascular risk factors in adolescents: biological and behavioral indicators]. Arq Bras Cardiol. 2006;86(6):439-50. have shown that individuals of both sexes with an inadequate total fat intake had a higher chance to develop high blood pressure. Campos et al.,1818 Campos W, Stabelini Neto A, Bozza R, Ulbrich AZ, Bertin RL, Mascarenhas LP, et al. [Physical activity, lipid consumption and risk factors for atherosclerosis in adolescents]. Arq Bras Cardiol. 2010;94(5):601-7. however, have reported no significant association of saturated fat and cholesterol intake with arterial hypertension in the city of Curitiba.

Regarding diet composition, the Dietary Approaches to Stop Hypertension (DASH), recommended by the National Institutes of Health (NIH),3535 National Institutes of Health. (NIH). National Heart, Lung, and Blood Institute. Your guided to Lowering your blood pressure with DASH. Bethesda (MD); 2006. considers other important aspects, such as consumption of whole grains, nuts, fish and poultry. In addition, the NIH emphasizes that the diet should be rich in potassium, magnesium, calcium and fibers, and have a low amount of sodium, red meat, candy, sugar and sugary beverages.3535 National Institutes of Health. (NIH). National Heart, Lung, and Blood Institute. Your guided to Lowering your blood pressure with DASH. Bethesda (MD); 2006.

Regarding those characteristics of a healthy diet, it is worth noting that the present study quantified only total fat intake, following the trend of most studies that report separately only a few aspects of the diet. Thus, the result of the present study should be carefully considered, because a high total fat intake can have a high proportion of poly- and monounsaturated fats, which are beneficial to health.3030 Lichtenstein AH, Appel LJ, Brands M, Carnethon M, Daniels S, Franch HA, et al; American Heart Association Nutrition Committee. Diet and lifestyle recommendations revision 2006: a scientific statement from the American Heart Association Nutrition Committee. Circulation. 2006;114(1):82-96. Erratum in: Circulation. 2006;114(23):e629. Circulation. 2006;114(1):e27. In addition, the individuals analyzed can consume other foods that favor blood pressure reduction, such as whole grains, nuts, fish, poultry, and others rich in potassium, magnesium, calcium and fibers.3535 National Institutes of Health. (NIH). National Heart, Lung, and Blood Institute. Your guided to Lowering your blood pressure with DASH. Bethesda (MD); 2006.

The other variables assessed in the present study showed no association with high blood pressure, the literature being controversial about that. Regarding sex, studies have reported higher chances of high blood pressure in males,1010 Gomes Bda M, Alves JG. [Prevalence of high blood pressure and associated factors in students from public schools in Greater Metropolitan Recife, Pernambuco State, Brazil, 2006]. Cad Saúde Pública. 2009;25(2):375-81.,1111 Romanzini M, Reichert FF, Lopes Ada S, Petroski EL, Farias Júnior JC. [Prevalence of cardiovascular risk factors in adolescents]. Cad Saúde Pública. 2008;24(11):2573-81. while others have reported an inverse or nonexistent association.1212 Christofaro DG, Ritti-Dias RM, Fernandes RA, Polito MD, Andrade SM, Cardoso JR, et al. High blood pressure detection in adolescents by clustering overall and abdominal adiposity markers. Arq Bras Cardiol. 2011;96(6):465-70.,1313 Pinto SL, Silva Rde C, Priore SE, Assis AM, Pinto Ede J. [Prevalence of pre-hypertension and arterial hypertension and evaluation of associated factors in children and adolescents in public schools in Salvador, Bahia State, Brazil]. Cad Saúde Pública. 2011;27(6):1065-76.

Regarding age, absolute blood pressure levels increase with age in childhood and adolescence, but this seems not to imply increases in high blood pressure levels in that age group.1414 Kelishadi, R, Sadri G, Tavasoli AK, Kahbazi M, Roohafza HR, Sadeghi M, et al Cumulative prevalence of risk factors for atherosclerotic cardiovascular diseases in Iranian adolescents. J Pediatr (Rio J). 2005;81(6):447-53.

Considering the daily energy expenditure, the literature has shown no association of physical activity levels with high blood pressure levels.1010 Gomes Bda M, Alves JG. [Prevalence of high blood pressure and associated factors in students from public schools in Greater Metropolitan Recife, Pernambuco State, Brazil, 2006]. Cad Saúde Pública. 2009;25(2):375-81.,1313 Pinto SL, Silva Rde C, Priore SE, Assis AM, Pinto Ede J. [Prevalence of pre-hypertension and arterial hypertension and evaluation of associated factors in children and adolescents in public schools in Salvador, Bahia State, Brazil]. Cad Saúde Pública. 2011;27(6):1065-76.,1616 Silva KS, Farias Júnior JC. Risk factors associated with high blood pressure in adolescents. Rev Bras Med Esporte. 2007;13(4):237-40. Nevertheless, a sedentary lifestyle established during childhood is known to strongly relate to a sedentary lifestyle in adulthood, increasing the susceptibility to the negative repercussions of a sedentary lifestyle in the future, including high blood pressure levels.33 Chen W, Srinivasan SR, Ruan L, Mei H, Berenson GS. Adult hypertension is associated with blood pressure variability in childhood in blacks and whites: the Bogalusa Heart Study. Am J Hypertens. 2011;24(1):77-82.,3636 Hardy LL, Dobbins TA, Denney-Wilson EA, Okely AD, Booth ML. Sedentariness, small-screen recreation, and fitness in youth. Am J Prev Med. 2009;36(2):120-5.

Regarding cardiorespiratory fitness, Stabelini Neto et al.,2121 Stabelini Neto A, Bozza R, Ulbrich AZ, Vasconcelos IQ, Mascarenhas LP, Boguszewski MC, et al. [Atherosclerotic risk factors associated with cardiorespiratory fitness and BMI in adolescents]. Arq Bras Endocrinol Metabol. 2008;52(6):1024-30. Rodrigues et al.,3737 Rodrigues AN, Perez AJ, Carletti L, Bissoli NS, Abreu GR. The association between cardiorespiratory fitness and cardiovascular risk in adolescents. J Pediatr (Rio J). 2007;83(5):429-35. and Fernandes et al.3838 Fernandes RA, Casonatto J, Christofaro DG, Cucato GG, Romanzini M. Ronque ERV. Cardiorespiratory fitness, surplus weight and high blood pressure in adolescents. Rev Bras Med Esporte. 2010;16(6):404-7. have shown no significant association with high blood pressure in both sexes.

Regarding tobacco use, some studies have reported no association in young individuals of the male sex1616 Silva KS, Farias Júnior JC. Risk factors associated with high blood pressure in adolescents. Rev Bras Med Esporte. 2007;13(4):237-40. and of both sexes,1010 Gomes Bda M, Alves JG. [Prevalence of high blood pressure and associated factors in students from public schools in Greater Metropolitan Recife, Pernambuco State, Brazil, 2006]. Cad Saúde Pública. 2009;25(2):375-81. because a dose-time-response relation is known to exist between tobacco use and the development of related diseases, that is, the risk increases according to the number of cigarettes smoked, especially, regarding the duration of the habit.3939 Nunes E. Consumo de tabaco: efeitos na saúde. Rev Port Clín Geral. 2006;22(2):225-44.

Regarding socioeconomic status, the literature is controversial, showing an association of high blood pressure levels with the highest socioeconomic levels,1515 Constanzi CB, Halpern R, Rech RR, Bergmann ML, Alli LR, Mattos AP Associated factors in high blood pressure among schoolchildren in a middle size city, southern Brazil. J Pediatr (Rio J). 2009;85(4):335-40. the lowest socioeconomic levels,1616 Silva KS, Farias Júnior JC. Risk factors associated with high blood pressure in adolescents. Rev Bras Med Esporte. 2007;13(4):237-40. and, even no association.1313 Pinto SL, Silva Rde C, Priore SE, Assis AM, Pinto Ede J. [Prevalence of pre-hypertension and arterial hypertension and evaluation of associated factors in children and adolescents in public schools in Salvador, Bahia State, Brazil]. Cad Saúde Pública. 2011;27(6):1065-76. According to Constanzi et al.,1515 Constanzi CB, Halpern R, Rech RR, Bergmann ML, Alli LR, Mattos AP Associated factors in high blood pressure among schoolchildren in a middle size city, southern Brazil. J Pediatr (Rio J). 2009;85(4):335-40. young individuals of higher socioeconomic levels would eat more and have a more sedentary lifestyle, increasing their chances of developing high blood pressure. Seabra et al.,4040 Seabra AF, Mendonça DM, Thomis MA, Anjos LA, Maia JA. [Biological and socio-cultural determinants of physical activity in adolescents]. Cad Saúde Pública. 2008;24(4):721-36. however, have reported that individuals of the highest socioeconomic strata tend to practice more physical activities than those less favored.

This study had some limitations, and their analysis can be important for future studies aimed at assessing blood pressure and its determinants. The first concerns the study design, which had a cross-sectional data collection. This type of study can have reverse causality, that is, exposure and outcome are collected simultaneously, making it difficult to determine which preceded the other.

Another limitation concerns the self-reported variables (daily energy expenditure, food intake, smoking, socioeconomic level and family history of arterial hypertension), because they rely on the subjects' understanding about the variables assessed. However, in large-scale studies those variables are extremely useful because they provide the evaluation of several individuals in one single assessment and because they are interesting alternatives when more precise measures cannot be used.

Conclusion

The present study showed a high prevalence of high blood pressure in adolescents of the city of Curitiba. In addition, it evidenced that taking a second blood pressure measure minimizes the estimates of that outcome among adolescents, probably because of their familiarization with the measuring protocol. Nevertheless, the estimates were greater than those of other Brazilian and international studies.

A positive family history of arterial hypertension and increased waist circumference associated with high blood pressure in adolescents. Therefore, special attention should be paid to young individuals with increased waist circumference, as well as to those with hypertensive parents. Those population subgroups should be the focus of public policies for blood pressure control in the young population, including actions related to the lifestyle adopted in the school and family settings.

  • Sources of Funding
    This study was partially funded by Capes.
  • Study Association
    This article is part of the thesis of Doctoral submitted by Rodrigo Bozza, from Programa de Pós-Graduação em Educação Física da Universidade Federal do Paraná (UFPR).

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Publication Dates

  • Publication in this collection
    05 Apr 2016
  • Date of issue
    May 2016

History

  • Received
    27 May 2015
  • Reviewed
    18 Nov 2015
  • Accepted
    19 Nov 2015
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