Prevalence of selected risk factors for cardiovascular deseases in adolescents with overweight and obesity*
Występowanie wybranych czynników ryzyka chorób układu krążenia u młodzieży z nadwagą i otyłością
Dariusz Gruszfeld 1, Piotr Socha2, Magdalena Hajduczek3, Zbigniew Kułaga4, Jerzy Socha2
1Klinika Patologii i Intensywnej Terapii Noworodka Instytutu „Pomnik-Centrum Zdrowia Dziecka”
Head: prof. A. Dobrzańska
2Klinika Gastroenterologii, Hepatologii i Immunologii Instytutu „Pomnik-Centrum Zdrowia Dziecka”
Head: prof. J. Ryżko
3Faculty of Psychology, University of Warsaw
Dean: prof. E. Czerniawska
4Public Health Division The Children’s Memorial Health Institute, Warsaw
Head of Division: Z. Kułaga, MD
* Acknowledgments. This work has been supported by a grant from Iceland, Liechtenstein and Norway through the EEA Financial Mechanism and the Norwegian Financial Mechanism. Project PL0255 ADOPOLNOR
Aim of the study: The aim of the study was to assess the prevalence of elevated blood pressure values and significant family history with respect to the incidence of cardiovascular diseases in overweight and obese adolescents.
Material and methods: Our study encompassed 4904 adolescents from randomly selected schools from the Wielkopolska province of Poland. Measurements of body height and mass were performed in all the school pupils. The adolescents were qualified to be included in the overweight and obese groups based on the BMI value, using the cut-off points according to Cole’s method. Blood pressure measurements were conducted according to the methodology and recommendations of the Fourth Report, with the application of the Polish blood pressure standards.
Within the group of students with normal body mass, overweight and obesity, the frequency of higher systolic and diastolic blood pressure and significant family history were calculated, and the relationship between the variables was calculated by means of chi2 test, assuming p<0.05. In order to calculate the odds ratio and the probability of incidence of higher systolic and diastolic blood pressure, the variables significant in the logistic regression model were taken into consideration.
Results: Overweight and obesity was observed in 845 subjects, which made up 17.2% of the population included in the study. Overweight and obesity were significantly more often observed in boys (485 – 22,2%) than in girls (362 – 17.0%) (p<0.05). In boys, the significant family history increases the odds ratio of prevalence of higher systolic blood pressure 1.90 times, obesity – 8.86 times and significant family history combined with obesity – 16.85 times, in comparison with the boys who have normal body mass and no significant family history. Obesity in girls increases the odds ratio of prevalence of higher systolic blood pressure by 9.24 times. Obesity in boys increases the odds ratio of prevalence of higher diastolic blood pressure by 5.88 and in obese girls the odds ratio of elevated diastolic blood pressure are 4.17 times higher.
Conclusions: 1. Obesity and positive family history in pupils of both genders considerably increased the probability of elevated systolic and diastolic blood pressure occurrence. This obliges to: – perform further medical diagnostics, towards identification of other risk-factors of cardiovascular diseases; – to qualify such adolescents to “groups of increased risk” (this information should be entered in the school medical records).
Key words: overweight, obesity, adolescent, arterial blood pressure, significant family history
Celem pracy była ocena występowania podwyższonego ciśnienia tętniczego oraz obciążonego wywiadu rodzinnego w zakresie występowania chorób układu krążenia u młodzieży z nadwagą i otyłością.
Materiał i metody: Badaną populację stanowiła młodzież z losowo wybranych szkół województwa wielkopolskiego. U wszystkich 4904 uczniów wykonano pomiary wysokości i masy ciała. Do grupy z nadwagą i otyłością kwalifikowano uczniów wg wartości BMI, przyjmując punkty odcięcia, wg metody Cole’a. Pomiary ciśnienia zostały przeprowadzone wg metodyki i zaleceń Czwartego Raportu oraz zastosowaniem ogólnopolskiej normy ciśnienia tętniczego.
W grupie uczniów z prawidłową masą ciała, nadwagą i otyłością, obliczono częstość występowania podwyższonego ciśnienia skurczowego i rozkurczowego oraz obciążonego wywiadu rodzinnego, a zależność między zmiennymi obliczono za pomocą testu chi2, przy p<0,05. Do obliczeń ilorazów szans i prawdopodobieństwa wystąpienia podwyższonego ciśnienia skurczowego i rozkurczowego, uwzględniono zmienne istotne w modelu regresji logistycznej.
Wyniki: Nadwagę i otyłość obserwowano u 845 badanych, co stanowiło 17,2% z całej badanej populacji.
Otyłość i nadwagę stwierdzono istotnie częściej wśród chłopców (485 – 22,2%), niż wśród dziewcząt (362 – 17,0%) (p<0,05). U chłopców obciążony wywiad rodzinny zwiększał szansę wystąpienia podwyższonego ciśnienia skurczowego 1,90 razy, otyłość 8,86 razy, a obciążony wywiad rodzinny i otyłość 16,85 razy. U chłopców otyłość zwiększała szansę wystąpienia podwyższonych wartości cisnienia rozkurczowego 5,88 razy. W populacji dziewcząt otyłość podwyższała szansę wystąpienia podwyższonego ciśnienia skurczowego 9,24 razy, a ciśnienia rozkurczowego 4,17 razy.
Wnioski: 1. Fakt stwierdzenia, że otyłość i obciążony wywiad rodzinny znacznie zwiększały prawdopodobieństwo wystąpienia podwyższonych wartości ciśnienia skurczowego i rozkurczowego obliguje do: – rozszerzenia diagnostyki lekarskiej w kierunku identyfikacji innych czynników ryzyka chorób układu krążenia; – zakwalifikowania tej grupy młodzieży do czynnego poradnictwa (ta informacja powinna zostać odnotowana w medycznej dokumentacji szkolnej).
Słowa kluczowe: nadwaga, otyłość, młodzież, ciśnienie tętnicze, obciążony wywiad rodzinny
The recommendations concerning the prevention of cardiovascular diseases in the youngest population underline the need to elaborate a family medical history with respect to the significant history of prevalence of cardiovascular disease, obesity, diabetes and other risk factors.
Significant family history is very often correlated to biochemical risk factors for cardiovascular disease. The prevalence of other numerous metabolic disorders to obesity has been stressed more and more often. This concerns not only disorders of glucose tolerance, but also hypercholesterolemia, increased concentration of insulin in serum. The observed dysfunction of endothelial tissue in the obese population may be one of the factors causing hypertension.
Taking into account the availability and cost of laboratory tests and reluctance to performing them by young persons “merely with overweight or obesity”, with absence of any somatic complaints – the necessity of biochemical parameters’ evaluation in all children and adolescents with elevated BMI values should be considered. Will the young persons’ psyche not be affected by being “stigmatised” with abnormalities or diseases that may, or may not, occur in the future?
The overweight and obese adolescents should be dealt with as a group under special preventive and medical care both in home and school environment.
AIM of the study
The aim of the study was to assess the prevalence of elevated blood pressure values and significant family history with respect to the incidence of cardiovascular diseases in overweight and obese adolescents.
Materials and methods
The population subject for the study encompassed 4904 adolescents, 10-18 years of age, from randomly chosen schools in Poznan, larger cities and smaller towns, as well as villages of the Wielkopolska province in Poland.
The sampling frames were the schools, and within the schools – school forms.
The number of population included in the study according to age groups is presented in table I. Aer obtaining parents’ permission (or the adolescents’ permission if they were more than 16 years of age) the anthropometric measurement of all the children was performed: body height and mass were measured according to anthropometric principles.
The BMI of every school pupil was calculated according to the formula: BMI = body mass (in kg)/height2 (in m). The adolescents were qualified to the overweight and obese group based on their BMI values, assuming the cut-off points incorporating the age and sex, according to Cole’s method (6).
Blood pressure was measured on three different days, in compliance with the methodology stipulated in the Fourth Report on the Diagnosis, Evaluation, and Treatment of High Blood Pressure in Children and Adolescents, assuming that the value of blood pressure is the average of the three measurements (7). School children were qualied to the group of high blood pressure based on the recommendations of the Fourth Report, with the use of the Polish standard (8). The adolescents whose value of systolic blood pressure and/or diastolic blood pressure were equal to and higher than the 90th percentile were included in the group of higher blood pressure.
Prior to the paediatric examination, the parents filled out a standardized questionnaire form which contained questions related to the closest family incidence of coronary disease, cardiac thrombosis, hypertension, diabetes, elevated cholesterol level, obesity, sudden deaths due to cardiovascular disease as well as other persistent heart problems. The analysis incorporated an interview concerning both parents: the mother and the father.
Within the group of students with normal body mass, overweight and obesity, the frequency of higher systolic and diastolic blood pressure and positive family history were calculated, and the relationship between the variables was calculated by means of chi2 test, assuming p<0.05. In order to calculate the odd ratio and the probability of incidence of higher systolic and diastolic blood pressure, the variables significant in the logistic regression model were taken into consideration, assuming the level of signicance at p<0.05. The calculations were performed with the use of STATISTICA 8.1 software.
Within the population selected for the study (4904), the total number of school children with normal body mass, overweight and obese amounted to 4304 (2176 boys and 2128 girls), which constituted 87.8%. Overweight and obesity was observed in 845 subjects, which made up 17.2% of the population included in the study. Underweight were 600 (12,2%) pupils and this group was not included in further statistics.
Overweight and obesity were significantly more often observed in boys (485 – 22.2%) than in girls (362 – 17.0%) (p<0.05) (tab. II, III).
From the population of 4304, the group of 1696 school children had a significant family history, which made up 39.4% of the population subject to the study. Despite the fact that overweight and obese boys more often had a significant family history in comparison with the boys with normal body weight the difference was not significant (p>0.05).
The increased value of systolic and diastolic blood pressure was significantly more prevalent in obese and overweight boys, in comparison with the boys with normal body weight (tab. II). From among the 485 overweight and obese boys subject to examination, 71 (14.6%) at the same time had significant family history of higher systolic and/or diastolic pressure (tab. II). The difference between this group and the boys with normal body mass who had a significant family history parallel to the elevated levels of blood pressure turned out to be more substantial (p<0.05) (tab. II).
From among 2128 girls included in the study, as many as 858 (40.3%) had significant family history. Overweight and obese girls considerably more often had significant family history in comparison with girls with normal body mass. The increased value of systolic blood pressure was observed in 94 (26.0%), and diastolic in 66 (18.2%) among the overweight and obese girls, and these values were significantly higher than in girls with normal body mass (p<0.05). The group of overweight and obese girls (70, i.e. 19.3%) considerably more often had significant family history and/or elevated systolic and diastolic blood pressure than the group with normal body mass (p<0.05) (tab. III). In the model of systolic blood pressure in boys, the significant variables were significant family history and obesity, in the model of systolic blood pressure in girls, as well as diastolic blood pressure in boys and girls, it was obesity only.
In boys, the significant family history increases the odds ratio of prevalence of higher systolic blood pressure 1.90 times, obesity – 8.86 times and significant family history combined with obesity – 16.85 times, in comparison with the boys who have normal body mass and no positive family history (tab. IV).
The probability of incidence of higher systolic blood pressure in obese boys with significant family history equals 0.51, i.e. elevated systolic blood pressure may occur in 51 out of 100 boys.
Whereas in boys with normal body mass and no significant family history, the probability of elevated blood pressure amounts to 0.06, i.e. elevated systolic blood pressure may occur in 6 boys out of 100 boys. Obesity in girls increases the odds ratio of prevalence of higher systolic blood pressure by 9.24 times (tab. V). The probability of incidence of higher systolic blood pressure in obese girls equals 0.47. In girls with normal body mass the probability of higher systolic blood pressure is just 0.09.
Obesity in boys increases the odds ratio of prevalence of higher diastolic blood pressure by 5.88 and in obese girls the odds ratio of elevated diastolic blood pressure are 4.17 times higher (tab. VI).
The incidence probability of higher diastolic blood pressure in obese boys equals 0.29, and in boys with normal body mass, the probability of higher diastolic blood pressure amounts to 0.06.
The probability of incidence of elevated diastolic blood pressure in obese girls amounts to 0.28. In girls with normal body mass the probability of incidence of elevated diastolic blood pressure is only 0.08.
Over the past decades, in the population of developmental age a growing percentage of overweight and obese children and adolescents has been observed. This has been confirmed by numerous studies of which the authors monitor the physical development of the youngest age groups (2). At the same time, besides the growing tendency to the incidence of excessive body mass, an alarming phenomenon of the growing number of adolescents with primary hypertension has been observed (1, 2, 3, 4, 5).
The program of early prevention of cardiovascular diseases, as the well as diagnostics and treatment of children and adolescents should take place based on the analysis of family context. The observed phenotypic similarities of children and parents with obesity and overweight may be of great use in the process of preventive activities (9).
The incidence of obesity in parents may have a significant impact on the frequency of incidence of obesity in children (10, 11). It is not only associated with a similar diet in parents and children, but also with the same style of spending free time and physical activity. The longitudinal observations started with obese adolescents indicate that their odds ratio of atherosclerotic lesions in coronary blood vessels and aorta in adulthood are higher than in other adults who had normal body mass in their youth (12).
The observations of other authors, similarly to our study, indicate a four times greater odds ratio of abnormal systolic blood pressure and a two times greater odds ratio of high diastolic blood pressure incidence in obese adolescents, in comparison with the adolescents with normal body mass (11).
Numerous studies indicate that, together with an increasing family prevalence related to the cardiovascular diseases and their risk factors, the percentage of obese children growing. These children do not only have high blood pressure, but also high concentration of cholesterol and high glucose levels (13, 14, 15).
The aforementioned reservations concerning the accessibility, cost and ecacy of “mass” laboratory tests in obese children and adolescents should make us first perform examinations useful in the monitoring of obesity.
The observed familial aggregation of risk factors in children should constitute an incentive to perform anthropometric measurements and blood pressure more frequently, which may allow not only to undertake prevention earlier, but also to perform appropriate diagnostics and treatment procedures.
1. Since obesity and positive family history in pupils of both genders considerably increases the probability of elevated systolic and diastolic blood pressure occurrence, it obliges to:
– perform further medical diagnostics, towards identification of other risk-factors of cardiovascular diseases;
– qualification of such pupils to “groups of increased risk” (this information should be entered in the school medical records).
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Adres do korespondencji / Address for correspondence:
Zakład Epidemiologii KMS Uniwersytetu Medycznego im. K. Marcinkowskiego
ul. Dąbrowskiego 79, 61-529 Poznań