Metabolic Syndrome in obese children – clinical prevalence and risk factors

Abstract

Background: Prevalence of childhood obesity increases worldwide. Some of the obese children develop metabolic syndrome (MetS) , who of them - remains to be determined. The aim of this study was indicate predisposing factors for metabolic syndrome,, especially those which can be modified.

Methods: The study comprised 591 obese children aged 10-12 years. Clinical examination, anthropometry, biometric impedance analysis, blood works (incl. OGGT and insulinemia) as well as dietary evaluation and physical activity were estimated.

Results: The risk factors of MetS or feature of this are: male, parent’s especially father’s obesity, low body mass at birth as well as omitting breakfast or dinner.

Conclusions: There are few risk factors of metabolic syndrome in obese subjects, also in obese children. Some of these predictors can me modified, especially those referring to lifestyle. Indicating and then influencing these factors can be one way to diminish metabolic syndrome development, such improving health and quality of life. Besides certain socioeconomic effects could be gain too.

Background

Prevalence of obesity is rapidly increasing. According to World Health Organization (WHO) in 2016 it affected as many as 650 million people and 2 billion adults were overweight. At the same time 41 million children younger than 5yrs were overweight or obese and over 340 million children and adolescents aged 5-19yrs were overweight or obese.¹ Number of children with obesity increases and one should expect that complications of obesity in this age group will increase too.

Obesity, defined as the excess of fat tissue, is wide spread all over the world and it affects all age groups. ² Obesity, among other, is well known risk factor of metabolic syndrome (MetS) which comprises cardiovascular diseases (CVD), diabetes mellitus (DM), hypertension, atherosclerosis as well as other complications.³ Although etiology of obesity is complex, genetic predisposition is permissive and, actually, interacts with environmental agents including physical activity and diet. Heritable factors seem to have 40–85% contribution in obesity’s etiology.⁴ Apart from genetic predisposition, other recognized constituents such as: metabolom, metabolic programming during both gestational and post gestational period can be modified to some extent. ⁴ Consequently development of obesity and its complications might be reduced.⁵

Metabolic syndrome is recognized consequence of obesity and it can occur as early as in adolescence. Certainly, not all obese children will develop all or any complications of obesity. Which one of children living with obesity are mostly prone to MetS remains to be fully elucidated.

In the systematic review of 85 studies in children, median prevalence of metabolic syndrome in all populations was 3.3% (range 0–19.2%), in overweight children it was 11.9% (range 2.8–29.3%), and in obese subjects − 29.2% (range 10–66%). For non-obese, non-overweight populations the range was 0–1% [6]. Almost 90% of obese children and adolescents have at least one feature of the metabolic syndrome. ⁷. On the basis of NHANES 1999 to 2002 data, the prevalence of metabolic syndrome in adolescents 12 to 19 years old ranged from 0–9.4%; variation in this estimate was the result of different criteria used to define metabolic syndrome. ⁸ In the report from BIOSHARE-EU, prevalence of metabolic syndrome in obese subjects ranged from 24–65% in females and from ≈ 43% to ≈ 78% in males and substantially exceeded the prevalence in metabolically healthy obese ones. ⁹ The divergences were conditioned by the country.

In the light of child’s dynamic growth and maturation population of children is unique. Obesity is diagnosed on the basis of percentile charts, when BMI > = 95th centile. Moreover, according to IDF consensus - commonly used by most of the authors - metabolic syndrome may be recognized in children not younger than 10yrs old. ¹⁰ It takes some time before metabolic syndrome complicates obesity. Nevertheless the younger the child becomes obese the earlier in life he or she might suffer from its complications. ¹¹ However one must remember that not all children suffering from obesity will develop MetS.

The aim of our study was to identify factors favoring the presence of one or all compounds of metabolic syndrome in obese children. Secondly, we analyzed the results in order to indicate which of them are modifiable.

Material And Methods

This study was a part of the “6–10–14 for Health” integrated weight management program for children with overweight and obesity from Gdansk, Poland, previously described. ^12–14

Analyzed data included children aged 10-12yrs attending the interventional program in 2011–2015. Children were screened in primary schools and if overweight or obesity was diagnosed they were invited to multidisciplinary, 12-month-long program. Patients flow is presented in Fig. 1.

All the children during first interventional visit were examined by pediatrician (incl. weight, height, waist circumference measurement), and bioelectric impedance analysis (BIA) was performed. All children were referred to blood works within 4 weeks from the first visit. Body mass, BMI centile, waist circumference centiles, blood pressure centiles were assessed using Polish centile charts, as recommended by WHO. ^15–17 Medical history was taken and collected data included: body mass at birth (below 2,5 kg was assumed as hypotrophy, more than 4,0 kg – macrosomy), parents’ BMI, any metabolic disease in family members, feeding pattern (original questionnaire, specific questions regarding breakfast and supper time and quality). Lifestyle and diet were evaluated too. Waist circumference (WC) over 90th percentile and waist- hip –ratio (WHR) > 0.8 for girls and > 0.9 for boys were interpreted as abnormal.

For children younger than 10 years old waist-hip-ratio (WhtR) seems to be more accurate than WC. Abnormal WhtR was defined when WhtR > = 0.5.

In our study, although all the participants were at least 10 years old, WhtR was also calculated.

Overweight was diagnosed if BMI centile was ≥ 85th and obesity was diagnosed when BMI was ≥ 95th centile on recommended centile charts. ¹⁵

Central obesity was recognized when WC was above 90th or WhtR was > = 0.5.

The results of biometric impedance analysis were assessed according to standard values. ¹⁸

Blood testes included: aminotransferases, lipid fractions, thyroid stimulating hormone, tyrosine, Hb1c, oral glucose tolerance test (OGTT) along with insulin level at the same time points and the results were compared to standard values for appropriate age and sex.

Physical activity was evaluated by means of Kash Pulse Recovery Tes t. ^20–21 and classified as excellent, very good, good, moderate, poor and very poor.

Nutritional habits were evaluated by the dietitian on the basis of data given by children and parents. Special attention was paid on breakfast (first course within 2hr after wake up) and dinner (last meal eaten 2 hr before sleep).

Metabolic Syndrome (MetS) was diagnosed according to IDF,²² in children with WC > 90th centile and at least two out of the following metabolic features: HDL < 40 mg/dl, TG > 150 mg/dl, glycemia > 100 mg/dl and blood pressure > = 130/85 mmHg.

Results

591 children aged 10-12ys who entered the program and fulfilled questionnaire and had blood works done were assessed in this study. None of the children had any chronic disease which could influence investigated parameters as well as no infection on the day of examination.

The girls were younger (p = 0,031), shorter (p = 0,028), had lower WC (p < 0,0001), lower WHR (p < 0, 0001), lower WhtR (p = 0,002) and lower DBP (p = 0,044) compared to the boys. Moreover, higher BMI centile (p < 0,001) and higher fat tissue content were characteristic for girls. Elevated systolic blood pressure (SBP) was found in 10% of children, with no difference between girls and boys (Table 1).

Based on BMI percentile criterion there were 401 overweight (67,9%) and 190 obese children (32,1%).

Obesity was diagnosed in 85 (30,9%) girls and in 105 (33,2%) boys whereas, 190 (69,1%) girls and 211 (66,82%) boys were overweight. Girls had higher BMI centile compared to boys (p < 0,0001).

Discussion

Prevalence of obesity is high worldwide, some find it pandemic. This disease is known to be one of the so called “lifestyle diseases” and it was fathered mostly upon adolescence and adults.

However, incidence of obesity in children is growing fast and the burden of its complications must be considered not only from medical but also socioeconomic point of view.

Obesity increases the risk of other diseases of affluence, such as: hypertension, dyslipidemia, glucose intolerance at the same time being a well known risk factor of CVD and MetS. ^23–26.

Many authors reported that children with BMI over 75th centile have higher morbidity and mortality of DM2 and CVD in adulthood. ^27–30. Thus, quality and expectancy of life certainly is and will be affected by obesity.

Metabolic syndrome became an epitome of obesity’s complications with high impact on human’s well-being.

Apart from various definitions of MetS in children, apparently not all teens with obesity develop metabolic syndrome or not even one of its components. Which of the obese children (in fact whole obese population) are especially predisposed to MetS is still not fully understood. Yet, knowing the risk factors of metabolic syndrome would allow to prevent the latter or at least minimise its prevalence and consequences.

In our study 12.9% of obese children 9–12 years old, participating in „6-10-14“ for health” had metabolic syndrome diagnosed − 10.9% of girls and 14.6% of boys. These results are similar to other publications. ³¹. It seems that prevalence of obesity and metabolic syndrome in children is more or less the same all over the world.

According to Abdullah et al. young age at the onset of obesity as well as time period it lasts are essential factors of MetS in adolescence. ³² Clearly, appropriate prophylaxis should be undertaken as soon as possible to stop his process..

Our main aim was to identify children who were at highest risk of developing MetS. Recognition of predisposing agents, which can be modified, may be crucial, since it is our deep believe that undertaking no prevention will lead to MetS eventually.

The results show that obese children with metabolic syndrome characterize with poor physical performance, bad nutrition habits and glucose intolerance with insulin resistance. Similarly to Mazur et.al., we also found that pathological WhtR predisposes to both MetS and syndrome’s certain components. ³³

In our study, we found that boys with low body mass at birth had more often MetS. Obviously this fact is irreversible, nevertheless it is known that metabolic programming, which begins in fetal life is going on after birth too. There is slight opportunity to influence this process by means of “healthy” lifestyle of pregnant woman and can be achieved by education of not only doctors and health providers but also mothers. Promoting exclusively breastfeeding with recommended weaning time presents to be easy way to influence metabolic programming and weight gain in fist 2–3 years of life.

Both or either parent’s obesity - especially father’s - might depict genetic predisposition to excess body mass in a child, but, on the other hand, illustrates family’s lifestyle. It is already known, that obese children more often skip breakfast. ³⁴. Contrary to some authors, we found that omitting dinner is related to metabolic syndrome or to components of metabolic syndrome too. This feeding pattern fits in modern model of life, characterized additionally with little physical activity and much sedentary time (at school, work and home). Similar observations have already been published.³⁵

Obviously, there is not much we can do about genetics. However, if genetic predisposition runs in the family it stands for a red flag and preventive measurements should be undertaken in order to alleviate unavoidable consequences of obesity and MetS.

Such, sound knowledge and education on energy balance (via proper diet and physical activity) as driving force against obesity should be promoted. Changes implemented for child’s prevention will cover beneficially whole family.

To our knowledge this is the first study on “factors” predisposing to metabolic syndrome” in obese children and teenagers, carried out in such a large, unanimous population (age, residency).

Conclusions

Among many risk factors of metabolic syndrome, beside those which are irreversible (such as body mass at birth, gender genetic predisposition etc.) there are many which are dependent on lifestyle. The latter, such as proper, increased physical activity, rational nutrition (regular ‘healthy” meals) can be modified and such the risk of metabolic syndrome in obese children can be diminished in inexpensive way.

The education and preventive companies addressed to health providers and parents are required in order to lessen morbidity of obesity and metabolic syndrome

List of Abbreviations

BIA               bioelectric impedance analysis

BMI              body mass index

CVD             cardiovascular diseases

DM               diabetes mellitus

HDL              high density lipoprotein

HOMA-IR     homeostatic model assessment for insulin resistance1

IDF               International Diabetes Federation

MetS            metabolic syndrome

OGGT          oral glucose tolerance test       

SBP             systolic blood pressure

TG                triglycerides

WC               waist circumference

WHO            World Health Organization

WhtR            waist- hip –ratio

Declarations

Ethics approval and consent to participate

This study was accepted by the Independent Bioethics Committee for Scientific Research at Medical University of Gdańsk. The study is registered in clinicaltrials.gov (NCT number): NCT04143074

Consent for publication

Not applicable

Availability of data and materials

The data that support the findings of this study are available from [third party name] but restrictions apply to the availability of these data, which were used under license for the current study, and so are not publicly available. Data are however available from the authors upon reasonable request and with permission of “6–10-14 for Health” integrated weight management program for children with overweight and obesity from Gdansk, Poland

Funding the City of Gdansk authorities. The City of Gdansk had no financial input to the presented manuscript nor they had an impact on design of the study and collection, analysis, and interpretation of data and in writing the manuscript.

Competing interests

"The authors declare that they have no competing interests" in this section.

Authors' contributions

AR-S  design of the work;  the  analysis, and  interpretation of data, patient recruitment, data collection and analysis, approval of the manuscrip

MB    design of the work , substantive revision, approval of the manuscript

AJ     design of the work, patient recruitment, data collection and analysis, paper draft, revision and approval of the manuscrip

ASS  designed work , revision and approval of the manuscrip

All authors read and approved the final manuscript

Acknowledgements : We thank our colleagues from “6-10-14 for Health” for their hard work and engagement.

All the authors declare no conflicts of interest.

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