Study of Cardiovascular Risk factors in Adolescents.
Walter Abraham, Gustavo Blanco, Gabriela Coloma, Alejandro Cristaldi, Natalia Gutiérrez, Luis Sureda,
SAHA Distrito Sudeste
Secretaria de Salud Partido Gral. Pueyrredón,
José Lijo López 5176. Mar del Plata (B7605FID).
Prov. de Buenos Aires, Argentina.
Recibido 01-OCT-2012 – ACEPTADO después de revisión 29-NOVIEMBRE-2012.
The authors declare not having a conflict of interest.
Scientifical evidence suggests that cardiovascular disease has its origin at early stages of life, and its risk is determined by the synergistic effect of cardiovascular risk factors over time. The frequent association with obesity, sedentarism, dyslipidemia and diabetes increases the atherogenic effect of arterial hypertension.
Material and methods. ERICA (Study of Cardiovascular Risk Factors in Adolescents) is an epidemiological study designed to determine, in a first step, the prevalence of hypertension and other risk factors associated with cardiovascular disease in an adolescent school population (n=1056) between 10 and 17 years old.
Results. In the ERICA study, 14.9% of the adolescents had high levels of blood pressure, including hypertensive and pre-hypertensive subjects. A third of teens checked had obesity and/or overweight.
Conclusions. ERICA results showed higher prevalence of hypertension, overweight and obesity in the study population than the the data reported in the literature.
|Key words: Hypertension. Obesity. Teenagers.
Rev Fed Arg Cardiol. 2013; 42(1): 29-34
Cardiovascular risk factors appear early in childhood and adolescence, and produce a negative repercussion on the quality of life . The WHO mentions ten risk factors responsible for a third of world mortality, with regional and developmental differences. The main ones are: hypertension, smoking, hypercholesterolemia, obesity, alcoholism, and an inappropriate diet.
Physiologically, blood pressure (BP) is considerably lower in children than in adults, but it increases gradually along the two first decades of life, and by the end of adolescence reaching values of adulthood.
Blood pressure in childhood and adolescence should be considered according to different variables, such as age, gender, weight, and size.
Unlike what happens in adults, there were no BP differences found between children of different races. Only the Bogalusa Heart Study  showed differences of blood pressure between white and African-American children, with higher values in the last group.
There is increasing evidence that essential hypertension would have its origins in childhood . Some observational studies have shown that premature children or infants with low weight at birth have a greater risk of suffering hypertension in adulthood than full-term infants or those with normal weight for the gestational age.
The genetic load is another important factor in the acquisition of hypertension. The children from hypertensive families tend to have BP values higher than children from normotensive families and on the other hand, the correlation of BP between adoptive parents and children is lower than between biological parents and children.
The prevalence of HTN in adolescence is not clearly defined. The epidemiological data from recent years in developed countries reveal that the average of blood pressure has increased in those age groups. Figures are published with variable prevalences, which are between 4.7 to 13% [4,5] in the population youngerthan 18 years old.
Just as in adults, HTN is classified into essential or secondary, with primary hypertension being the main cause since ten years of age.
Many children and teenagers today are identified as carriers of genetic or metabolic risk factors for a future high BP, which makes it necessary for the physician to know and manage them at an early age to apply measures when the child-adolescent is still normotensive, preventing the appearance of HTN or finally delaying it as much as possible.
It is then of essential interest to know the prevalence of hypertension and also the relation with other cardiovascular risk factors in this age group to establish an optimal preventive and therapeutic strategy.
- To identify the prevalence of hypertension in teenagers between 10 and 17 years old, in both genders.
- To determine anthropometric parameters of the studied population.
- To identify other cardiovascular risk factors (obesity, hypercholesterolemia, hyperglycemia, sedentarism and smoking) and family history and weight at birth.
- To look for a statistically significant association between the development of HTN, and the history of low weight at birth, overweight or current obesity.
- To evaluate diet behaviors in teenagers.
MATERIAL AND METHODS
ERICA is a descriptive cross-sectional study in a sample of 1056 teenagers in school, between 10 and 17 years, of both genders, collected between the months of June of 2009 and December of 2010 in the city of Batán, district of Gral. Pueyrredón, Province of Buenos Aires (Population of Batán according to the 2001 census: 9597 inhabitants) .
In every school, an Informed Consent was given to each student, along with a structured survey to be completed by the parents or tutors of the teenagers, with the aim of gathering identification data, weight at birth, hereditary and family history, and diet habits.
There were 1056 teenagers authorized by their parents and tutors and who agreed to participate in the study (survey plus physical examination) and 245 of them accepted to have blood extracted in a fasting state to make biochemical determinations.
The physical examination was made in each of the schools, where anthropometric measurements were made with a measuring rod and calibrated digital scales and measurement of blood pressure.
At the time of making a physical examination, questions were made about the out-of-school physical activity, addition of salt to food, smoking and if BP had been controlled in previous medical visits.
The measurements of BP were made with the patients not having smoked or ingested coffee in at least 30 minutes, in a sitting position, with an automatic sphygmomanometer OMROM HEM-742 INT, where three measurements were made in the right arm with a two minute difference between each other, with a fourth measurement being the decision of the examining physician.
Weight, height, and waist circumference were determined.
These data were entered into the BP percentile calculator  and percentiles of Body Mass Index  of the Up to Date version 17.1.
For the diagnosis and classification into normal pressure, pre-hypertension and hypertension, such calculators use the criteria of the Fourth Report on the Diagnosis, Evaluation, and Treatment of High Blood Pressure .
For the diagnosis and classification into low weight, normal weight, overweight or obesity, the calculators are based on data from the National Health and Nutrition Survey (NHANES), CDC (Center for Disease Control) and National Center for Health Statistics .
Low weight was considered as less than 2,500 gr at birth.
The teenagers who had a percentile of BP<90 were considered normotensive.
The teenagers whose average of BP was equal or greater than percentile 90, were scheduled for a second evaluation of their BP, which was carried out following the same procedure as in the first visit. After this second evaluation, they were definitely categorized as normotensive, pre-hypertensive or hypertensive.
In 245 teenagers the parents of whom had consented, blood was extracted in a fasting state to determine total cholesterol, HDL, LDL, triglycerides, glycemia and creatinine.
The samples were analyzed in the laboratory dependent from the Secretary of Health of the Municipality of Gral. Pueyrredón.
Dyslipidemia was defined by the presence of at least one of the following parameters: total cholesterol ≥200 mg/dl, LDL-C≥120 mg/dl, HDL-C<35 mg/dl or triglycerides≥150 mg/dl .
The values of glycemia for normal glycemia, altered glycemia in a fasting state or diabetes, were defined according to the ALAD guidelines (Asociación Latinoamericana de Diabetes) .
Smokers were considered as such when one or more cigarettes were consumed per day.
The statistical analysis was made with the EPI Info system, 3.5.1 2008.
From the 1056 teenagers evaluated, 580 were women (54.9%) (Figure 1).
112 teenagers (10.6%) were hypertensive and 45 (4.3%) pre-hypertensive, after at least 6 measurements of blood pressure recorded in 2 different visits (Figure 2).
140 teenagers (13.3%) presented obesity and 198 (18.7%) were overweight (Figure 3).
In the written survey delivered previously, the weight at birth was included of 825 of the participating teenagers, 50 of them (6.06%) mentioned history of low weight at birth.
12.6% of the mothers and 7.95% of the fathers knew they were hypertensive.
44.6% of the teenagers added salt to food. N: 1041 (Figure 4).
1.6% mentioned smoking.
52.5% did not perform out-of-school physical activities. N: 1041 (Figure 5).
884 of the teenagers surveyed, answered the question about whether they had had their BP measured previously. 62.2% of them said no (Figure 6).
From the 245 teenagers in whom lab tests were made, 39 (15.9%) presented dyslipidemia. 41% of the teenagers with dyslipidemia had overweight or obesity.
Only 1 was registered with altered glycemia in a fasting state.
A statistically significant association was found (p<0.01) between the development of HTN and the presence of overweight or obesity (Table 1).
Low weight at birth did not show a statistically significant association for the development of pre-hypertension or hypertension.
Around 15% of teenagers had increased figures of BP, considering both hypertensive and pre-hypertensive individuals. This result was slightly above those reported in literature. In the Consensus on Risk Factors for Cardiovascular Disease in Pediatrics, in the section about hypertensionin children and teenagers, of the Sociedad Argentina de Pediatría (SAP)  a prevalence of hypertension is reported of 1 to 3% in childhood, which reaches 10% in adolescence. Regrettably, such figures are much above those from previous decades, mainly in developed and developing countries, surely associated to the increase in the cases of child obesity.
A significant number of evaluated teenagers, had never had their BP measured before the medical visits made. The different guidelines and consensus existing on hypertension in children and teenagers, like the Fourth Report on the Diagnosis, Evaluation and Treatment of High Blood Pressure  and the Consensus of the European Society of Hypertension about the Management of Hypertension in Children and Teenagers , advise that blood pressure should be measured in every consult in every healthy child older than 3 years, and in younger children, BP should be measured in the special circumstances in which there could be more risk of hypertension, as in the case of neonatal diseases that required intensive care, congenital heart diseases or kidney diseases, and where there are hints of a greater intracranial pressure or a treatment with drugs that increase blood pressure.
The Sociedad Argentina de Pediatría, through the abovementioned consensus  and the Sociedad Argentina de Hipertensión Arterial (SAHA) in their Guidelines about the diagnosis, study, management and follow-up of hypertension  advise measuring BP since birth.
There is marked evidence on this recommendation, but it seems to be, according to the data we gathered in our work, that BP measurements are not an established practice between the physicians that provide care to our children and teenagers. How can we, physicians, convince the general population to control their blood pressure, if we are not convinced of how important it is in the physical examination? Believing that hypertension is just a problem in adults, is a severe mistake that prevents us from intervening early on the evolution of this devastating disease.
A third part of teenagers had obesity and/or overweight. The percentage of teenagers found with overweight (overweight 18.7% or obesity 13.3%) is above that reported by Freedman DS et al  of the Bogalusa Heart Study, where a prevalence of overweight of 11% is described for the group between ages 5 and 17. If we compare the data with papers from our country and more recent times, as for example, the work by Dr. Kovalsky et at , where a prevalence of overweight of 20.8% and of obesity of 5.4% is published, over a sample of 1289 teenagers; or the work by Dr. Pedrozo in the city of Misiones , over 532 students with ages between 11 and 20 years, where 11.7% presented overweight and 3.4% obesity, our data seem to show that the epidemic of child obesity is openly spreading.
These data become more relevant when we relate overweight, obesity and blood pressure values. As shown in Table 1, teenagers with overweight (RR=2.55) and obesity (RR=5.33) had a greater risk of developing HTN in comparison with those with normal weight.
Almost half of the teenagers were used to add salt to their food, and more than half of those surveyed did not perform physical activities other than those scheduled in school. The literature showing that the increase in sodium in diet is accompanied by increase in BP values is numerous. Likewise, it has been widely shown that performing aerobic physical activity generates a decrease in the figures of blood pressure, regardless of weight loss. Both “unhealthy” conditions enhance the increase in blood pressure, and the fact that they are present at an early age makes it worse. It is very likely that the large majority of teenagers that were not used to perform out-of-school physical activity, may become sedentary by the end of high school.
Dyslipidemia. The prevalence of dyslipidemia in teenagers varies in the bibliography consulted and this largely depends on the parameters of the lipid profile being evaluated and on whether groups with normal weight or overweight are considered. The FRICELA study  reports that in Argentina, 11.7% of teenagers presented values of total cholesterol above 200 mg/dl.
The study by Arjona Ortegón et al, from Costa Rica  presents similar values in regard to the prevalence of increased total cholesterol (12.35%) and shows a prevalence of hypertriglyceridemia of 12%, low HDL-C of 9.9% and high LDL-C of 13.3%. The study of Salazar Vázquez et al  presents a prevalence of hypertriglyceridemia of 7.3% and 29.1% considering the absence or presence of obesity, respectively.
For the ERICA study, it was considered that the alteration of any of the parameters, whether high in isolation or mixed with others, was enough to define the presence of dyslipidemia, as stated by the Consensus on Risk Factors of Cardiovascular Disease in Pediatrics of the SAP, in the section on hypercholesterolemia  (Figure 7).
A greater number of teenagers to undergo lab tests to determine their lipid profile would allow a better analysis of the results found.
The epidemic of obesity, regrettably, has moved to earlier ages in life. Social and cultural changes typical of westernization, with an increase in saturated fat and food rich in sodium in the diet, along with a reduction in physical activities, lead us to find with an increasing frequency, children with overweight and obesity, and as it was to be expected, with an increase in the levels of blood pressure.
There is a wrong conviction that cardiovascular disease (CVD) is proper of adult life, without taking into account that CVD starts at an increasingly early age, wasting a change to intervene early and more efficiently.
Because of what was mentioned, we can state that the determination of blood pressure should be made systematically in the physical examination of children and teenagers, with this being an inexpensive intervention and with a high impact that would facilitate an early detection of hypertensive cardiovascular disease.
The implementation of guidelines about diets and lifestyles, low sodium ingestion, normalization of body weight, along with the stimulation for the practice of regular physical activity, contribute a significant additional benefit to control cardiovascular risk factors, favoring a healthy state in teenagers and young adults.
The authors of this paper thank the parents and students of the educational community of the City of Batán, since without their participation we would not have been able to make it.
Likewise, we are also grateful to the directors, professors, teachers, monitors, and general staff of the schools where this work was conducted: Basic Primary School Nº23 and Basic Secondary School Nº57 of Boquerón, Primary School Nº51 and Secondary School Nº43 of the San Francisco Location, Primary and Secondary School of the Los Ortiz Location, Primary and Secondary School of Chapadmalal, School Nº7, School Nº9, School Nº 32, Nuestra Señora de Luján School and Caraludme School, from the city of Batán.
We also thank the Secretary of Health of the District of Gral. Pueyrredón, Dr. Alejandro Ferro, for his unconditional support and the friends we mention next, for their contributions to realize this study: Dr. Hugo Morales, the Biochemists Martín Biscaychipy and Daniela Escurra, the B.S. Mirta Pereira, Mónica Martínez and Jadranca Juric, the Lab Technicians Carolina Gallardo Jan and Marta Elvira and the Secretary Leticia Paredes. All of them. Thank you for your priceless cooperation.
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Publication: March 2013