Revista Adolescência e Saúde

INTRODUCTION

Cardiovascular Diseases (CVD) have a great influence in the current epidemiological scenario, since they comprise the main cause of death worldwide. In 2015, approximately 17.7 million people died due to CVD. Of these, approximately 7.4 million were due to coronary heart disease and 6.7 million due to stroke¹.

The prevalence of CVD in developing countries has grown over the years, with systemic hypertension (SAH) being the main risk factor1. The increase in the prevalence of SAH in children and adolescents has become an important public health problem at present². In a recent systematic review and meta-analysis, which included 22 studies encompassing 14,115 Brazilian school-age adolescents, SAH was identified as prevalent, with the southern region having the highest number of cases (12.5%)³.

In Brazil, several studies have investigated the predictive capacity for hypertension of the anthropometric indicators in the evaluation of risk factors in the childhood and adolescent age group, due to the ease of measurement and low cost, however the results are still conflicting . Among these, the study conducted by Moreira et al.⁴ encompassing 1,716 adolescents aged 10 to 16 years, showed obesity as the main factor associated with SAH. As another prospective cross-sectional study conducted with 1221 children and adolescents (14 to 17 years), it identified a significant positive correlation between body mass index (BMI) with systolic blood pressure (SBP) and diastolic blood pressure (DBP) 5 In the study conducted by Burgos et al.⁶, waist circumference (WC) in children and adolescents (7-18 years) proved to be a predictor of risk for SAH.

In view of the above, this study was carried out with the objective of estimating the ratio of possibilities of some risk factors for the development of high levels of pressure in adolescents from 6 to 9, enrolled in schools of the public network in a city of the south of Brazil.


METHOD

The study that was characterized as transversal was carried out in schools of the public network of a city in the South region of Brazil, between November 2015 and May 2016. Adolescents who frequented between the 6th and 9th years of fundamental education were included in the study, with ages between 11 and 18 years. Those who presented pathologies or chronic conditions that prevented or limited the practice of physical activities, as well as pregnant women were excluded.

Initially, the authorization of the Regional Coordinator of Education was obtained, after the authorization the schools were drawn among the administrative regions in order to guarantee the representativeness of each one. Consequently, a contact with representatives of the schools was conducted, aiming at the exhibition of the proposed activities and clarifications about the importance of the study, as well as obtaining authorization to contact the students. The study was approved by the Local Research Ethics Committee under CAAE n °. 33665614.8.00.00.5346 and those responsible authorized the participation of the individual in the investigation from the signing of the Term of Free Cleared Consent.

The evaluations were initiated only after the authorization of the parents or guardians and the agreement of the students. The evaluators were previously trained based on a protocol for standardizing data collection procedures, established in order to minimize possible intro and inter-rater errors.

The anthropometric variables of the results measured included: weight, height, BMI, CC, hip circumference (CQ) and waist-hip ratio (HRQ). For these purposes, the weight was obtained by weighing in calibrated, digital and portable scales of the Plenna brand (Sport model), with a maximum capacity of 150 Kg, with divisions of 100 grams, with the weighing carried out with the individual barefoot and with the least amount of clothes possible. Height was evaluated using a Plenna brand stadiometer (model 206), with an accuracy of 0.5 centimeters (width of measurements from 120 to 220 cm). The calculation of the BMI was obtained using the ratio of body mass / height squared, whose value was expressed in kg / m2. The cut points used to determine the overweight and obesity used were those suggested by the International Obesity Task Force (IOTF)⁷.

The CC was measured through a flexible measuring tape with a precision of 01 mm. For the measurement of the CQ, the tape measure was placed horizontally around the hip in the most protruding part of the gluteus. These measures (CC and CQ) allowed the construction of the waist-hip ratio (RCQ), obtained by the quotient between the perimeter of the waist and the perimeter of the hip and were classified according to what was proposed in the study by Taylor et al. al.⁸.

The measurement of BP was performed by the indirect auscultation method, through a stethoscope (Littmann Classic III 5803) and a sphygmomanometer (Missouri Industria e ComércioLtda, Brazil) and classified according to the budgets established by the 4th Brazilian Hypertension Directive⁹. The first measure was disregarded, being considered the second measure in the statistical analyzes. The PA was categorized into: without high pressure corresponding to SBP and DBP values that were below the 95th percentile, and with high pressure, values of SBP and / or DBP equal to or greater than the 95th percentile, considering sex, age and height¹⁰.

The family history for CVDs was evaluated by means of a standardized questionnaire considering the occurrence of SAH, diabetes and coronary artery disease, cerebrovascular accident, renal failure and peripheral vascular disease in first-degree relatives. The level of physical activity was measured through the International Physical Activity Questionnaire (IPAQ) in the reduced version, reproduced and validated for the population studied¹¹. To classify the sample, the IPAQ considers the criteria of frequency and duration in four categories: very active, active, irregularly active and sedentary.

The evaluation of food consumption markers of the adolescents was investigated through the Food Consumption Marker Form in the Basic Attention available by the SISVAN-Web and adapted by the author of the study12. In order to classify the food habit as adequate and inadequate, the recommendations established in the Guidelines for the Evaluation of Food Consumption Markers in Basic Care¹² were used.

The socio-economic data were evaluated based on the schooling data of the head of the family and possession of the type and number of domestic equipment in the home, being classified according to the criterion of the Brazilian Association of Research Companies, which classifies the population in the classes from A to E, being A1 and A2 classified as high, B1 and B2 as average and C, D and E as low¹³.

Sample's size calculation

The calculation of the sample size was based on the data obtained in the study pilot with 174 individuals. Therefore, it was possible to detect an association between the waist-hip ratio (RCQ) and the BMI, considering a level of significance of 5% (p <0.05) and the power of 80% (WinPepi program version 10.5). ) a minimum sample number of 100 individuals were necessary.

Statistical analysis

The data were analyzed through the IBM SPSS Statistics program (version 20.0), and evaluated for normality by the Kolmogorov-Smirnov test. The categorical data were presented in absolute frequencies and percentages. The continuous data with normal distribution were presented in average and standard deviation. The independent variables (sex, socioeconomic level, family history, BMI classification, level of physical activity and eating habits), to identify statistical differences in the prevalences presented between the variable of interest. The reason for the possibilities of individuals to present the risk factors for high levels of pressure was established by OR estimates, through binary logistic regression, adopting a confidence interval of 95%, with alpha level stipulated in p < 0.05.


RESULTS

The study was initially presented to 310 adolescents, where 250 agreed to participate in the research and directed the term to the parents / guardians. For specific reasons, 32 parents / guardians didn´t allow the participation of the adolescent and 53 terms were forgotten, making it impossible to insert them into the investigation. Thus, the sample consisted of 174 adolescents, of whom 59.2% (n = 103) were female, with an average age of 12.63 ± 1.28 years. The demographic, anthropometric characteristics, level of physical activity, socioeconomic level, blood pressure of the sample, family history of CVD and eating habits are presented in Table 1.




When evaluated together, overweight and obesity raised the odds ratio for the development of high blood pressure levels equal to 5.76 (95% CI 1.77-18.71) in relation to adolescents without these risk factors . However, the other independent variables analyzed in the study as: sex (male / female) (OR = 1.26, 95% CI 0.40-3.93), socioeconomic level (OR = 0.68 IC 95% 0 , In accordance with current regulations in the field of public health, and dietary habits (OR = 3.09, 95% CI 0.38-24.65) were not considered predictive for the development of high levels of pressure ( Table 2).




DISCUSSION

This study showed that overweight and obese adolescents enrolled in schools of the public network of a municipality in the south of Brazil presented 5.7 times more possibilities of developing high levels of pressure in relation to adolescents without these risk factors. This positive association between obesity and the risk of developing HAS was also observed in other studies. Gomes et al.¹⁴ evaluated 1,878 students (14 to 20 years old), in the city of Recipe-PE, where the presence of obesity increased the risk of HAS by 4.19 times, while overweight increased the risk by 2.37. times, these being the main factors associated with the disease. Moreira et al.4 analyzed 1,716 students from public and private schools (10 to 16 years old) from the city of Cuiabá-MT, observing that obesity increased by 1.27 times the probability that adolescents had HAS.

Given this context, evidence shows that BMI has been considered the best parameter to predict the risk of high levels of pressure in children and adolescents15. This finding is clinically relevant because it is a non-invasive indicator, low cost and easy to apply15. Thus, the IMC can be used as a classification tool for the development of the HAS.

In fact, the BMI was used in other investigations whose results corroborate those of the present study and suggest an interrelation between obesity and high levels of pressure in school adolescents. Dulskiene et al.16analyzed a population of children and adolescents aged 12 to 15 years, finding a strong association between obesity (based on BMI) and the risk of the individuals evaluated developing SAH (OR = 6.64). Another study conducted in school-age individuals (6 to 14 years) also observed the association between overweight (OR = 1.62) and obesity (OR = 3.60), measured through the BMI, in terms of the risk to develop HAS¹⁷.

Considering the other risk factors analyzed (sex, socioeconomic status, family history for CVD, physical activity level and eating habits), no possibilities were found in the risk of developing high levels of pressure in the present study. Similarly, Nascimento et al.¹⁸ didn´t observe an association between the level of physical activity (active / inactive) with the possibility of developing SAH. In another study, there was also no association between the level of physical activity (active / inactive) and socioeconomic data with the risk of developing pre-hypertension and hypertension in children and adolescents in public schools in Salvador¹⁹. However, there was an association between inadequate dietary intake and the female sex with the possibility of developing pre-hypertension and HAS, which differs from the present study. Possible explanations for these discrepant findings include regional disparities, possible omissions of information by researchers and loss of information about the consumption of foods not listed in the Food Consumption Markers Form.

Although in the present study the gender of the participants has not had a positive association for the development of high levels of pressure, Müller et al.²⁰, in a study conducted in the city of Santa María-RS, with a sample of 576 adolescents , obtained significant results for this variable. This divergence is probably related to the age differences of the adolescents analyzed in the studies, which in the present study averaged 12.63 ± 1.28 years, and that of Müller et al. was 16 ± 1.2 years, which affects important biological differences, such as hormone production, sexual maturation or body composition.

In relation to the family history of CVD, a study conducted by Vieira et al.²¹, in the municipalities of Valle del Taquari-RS, with 914 adolescents (13 to 17 years old), there was a significant relationship between the alteration in the blood pressure levels of HAS as a family. Differently, in the present study, the family history of CVD wasn´t associated with the possibility ratio for the development of high levels of pressure.

This study has some limitations that must be considered: first, because it is a cross-sectional study, the interpretation of the results may be limited, due to the impossibility of establishing cause and effect relationships; second, the analyzed data come from a single municipality and; third, the indirect measurement of abdominal fat through CC. Another potential limitation that should be considered involves measuring BP in a single moment, which could overestimate the values obtained. However, epidemiological studies have considered the second value or the average of the BP to investigate the prevalence of high levels of pressure. Finally, it wasn´t possible to determine the reliability between evaluators for the measurement of the PA, however, it is emphasized that the evaluators were intensively trained and oriented.


CONCLUSION

The results of this study showed that overweight and obese adolescents enrolled in schools of the public education network of a municipality in southern Brazil have a greater possibility of developing high levels of pressure in relation to adolescents without these risk factors. . Thus, it is inferred that the measurement of the BMI anthropometric indicator is a simple and easy option for predicting high levels of pressure that can be used in school, since this is an important space for health monitoring. Furthermore, given the social, economic and demographic heterogeneity of our country, the identification of regional risk factors that are associated with the increase in the probability of developing high levels of pressure are of great relevance, since they contribute to early detection, favoring the promotion of a healthy lifestyle, as well as actions to control the risk factors considered modifiable associated with the evaluated result.


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