The effect of body mass index and gender on lipid profile in children and adolescents in Saudi Arabia.

Objectives: The objectives of this study were to study the relationship between lipid profile components among different body mass index (BMI) groups and investigate the association between gender and BMI. Methodology: This cross-sectional study included 218 children and adolescents; 104 males and 114 females. Accepted age range was from 2 to 18 years. Data were collected from February to May during the year of 2017 and were analyzed using the Statistical Package for the Social Sciences. Standard deviation (SD) for BMI was calculated based on the World Health Organization guidelines. Lipid profile results were reviewed from laboratory reports.
Results: Nearly 10.6% of the study population were found to be overweight; another 22.1% were suffering from obesity, of which 7.1% were morbidly obese. Children who had high levels of low-density lipoprotein (LDL) and low levels of high-density lipoprotein (HDL) were found among higher BMI groups, with elevated cholesterol levels noted in patients of increased weight. An increase in HDL levels was noted in 71% of the children who avoided fast-food consumption. Significant gender predisposition to changes in BMI was not found (P = 0.467).
Conclusion: High BMI was found to be associated with increased levels of LDL cholesterol and decreased levels of HDL cholesterol. No significant association between gender and changes in lipid profile was established (P = 0.898). Recommendation: All pediatricians must keep an open eye on overweight and obese children, routinely taking their weight measurements and screening for dyslipidemia by obtaining a full lipid profile for every child whose weight is 2 SDs above the mean.

INTRODUCTION

The World Health Organization (WHO) regards obesity as the accumulation of excess fat that poses a direct risk to health. In terms of body mass index (BMI), which is a crude population measure for obesity, obesity includes values 2 standard deviations (SDs) above the mean weight for age and gender, while overweight covers values between 1 and 2 SDs above the mean.[1] Results from comprehensive studies are now causing great concern as they are showing a global increase in the rates of overweight children worldwide, including Saudi Arabia.[1234] The Middle-East is contributing to the global epidemic of obesity with prevalence rates of obesity and overweight in Saudi being 9.3% and 23.1%, respectively, for school-aged children between 5 and 18 years and 6% and 15.7%, respectively, for preschoolchildren aged between 0 and 5 years.[56] It is estimated that by the year 2020, three quarters of all deaths would be attributable to noncommunicable diseases, of which obesity is a major risk factor.[7] Several studies have confirmed the link between dyslipidemia in the setting of obesity and high BMI.[8910] Cardiovascular diseases (CVDs) are an example of the most predominant noncommunicable diseases, widely known as the number one cause of mortality worldwide. They are associated with both obesity and dyslipidemia.[111213] The most common dyslipidemias that have been associated with obesity are elevated triglycerides (TGs) and low-density lipoprotein (LDL) and decreased high-density lipoprotein (HDL) levels.[1214] As evidence suggests, high serum HDL and LDL levels are associated with longevity and low HDL-cholesterol (HDL-C) level is associated with an increased cardiovascular risk, particularly if serum cholesterol and TGs are also elevated.[15] Among different characteristics that contribute to metabolic syndrome, an abnormal lipoprotein profile plays the basic role,[16] with LDL-cholesterol (LDL-C) values achieving the gold standard parameter for the evaluation of CVD risk.[17] Moreover, while CVDs are rare in childhood, these factors and their predisposition to coronary artery disease (CAD) are seemingly related to the likelihood of childhood obesity persisting into adulthood.[18] Therefore, we address these issues now in an aim to benefit our children prospectively and decrease their cardiovascular risk in the future. Controversy regarding gender predisposition toward higher BMI was raised as a result of some studies claiming an increase in the prevalence of overweight rates among females, rendering them more exposed to the negative health consequences of obesity. However, other studies have argued the opposite, which is that the higher prevalence was reported more frequently among males.[1] As part of our study, we hope to investigate the probability of gender bias toward higher BMI throughout childhood.

METHODOLOGY

Study design

An institutional ethical approval and patient consent had been obtained prior to the commencement of this study. This study is a descriptive, cross-sectional study that was carried out throughout the year 2017 during the months of February to May. Data were collected from patients attending endocrine outpatient clinics in Jeddah, Saudi Arabia. The sample size encompassed 218 patients; 104 (47.7%) of which were boys and the other 114 (52.3%) were girls. All children between the ages of 2 and 18 years were included, regardless of their gender. Participants’ mean age was 9.9 (±2.5) years. To properly assess the correlation of BMI with abnormal lipid profiles, patients with chronic illnesses that may interfere with findings, such as diabetes, or on certain medications known to affect aspects of the lipid profile, were excluded from the study. Those whose BMI SD values were out of range or their height and weight measurements were missing were excluded as well. For patients who were too young to be interviewed, below 8 years of age, their caretakers were approached instead. Questions asked encompassed the child's detailed medical and nutritional history, in addition to their level of activity and demographic background. Laboratory reports were reviewed and lipid profile test results were noted. The reference values used in this study were 0–5.2 mmol/L for total cholesterol, 0–3.57 mmol/L for LDL, 0.9–1.55 mmol/L for HDL, and 0.3–2.3 mmol/L for TGs. Participating individuals or their guardians confirmed a fasting period of 12 h prior to blood withdrawal. The height and weight of all patients were then documented using a single scale rounded up to the highest 0.1 kg for weight and a mechanical beam scale with a height rod rounded up to the nearest centimeter (cm) for height. BMI was further calculated by dividing the value of weight in kilogram by the value of height in square meters. Considering that BMI is a convenient method of screening for obesity and is regarded a suitable alternative for direct measure of body fat, children were classified into four categories. In concordance with the WHO, those with a BMI within 1 SD of their age and gender were considered normal, those between the 1 and 2 SDs belonged to the overweight category, those >2 SDs were assigned to the obese category, while those exceeding 3 SDs were placed into a morbidly obese category.

Statistical analysis

Data were interpreted using the 16th version of the Statistical Package for the Social Sciences (SPSS, SPSS 16, IBM, Armonk, NY, United States of America). Correlation coefficients between BMI and lipid profile components (total cholesterol, LDL, HDL, and TGs) were calculated and then tested for significance. Simple descriptive statistics were reported in proportions for qualitative variables and in mean and SD for quantitative variables (e.g., mean of cholesterol, LDL, HDL, and TG among BMI levels). Variations of lipid profile means among different BMI groups were tested using one-way ANOVA. A linear regression was performed to evaluate the prediction of each component of the lipid profile on log BMI kg/m2. An independent sample t-test was used to test the difference in each of the mean components of the lipid profile among genders. The results were considered statistically significant if P < 0.05.

RESULTS

Nearly 10.6% of the population were found to be overweight and 22.1% were obese, of which 7.1% were morbidly obese. Only 67.3% of the population were found to be within the normal range for weight according to their age and gender. These results were associated with changes in lipid profile, with a sole exception of TGs, of which no relationship was established with either obesity or logBMI (P = 0.467). Table 1 summarizes the relationships between various components of the lipid profile to different values of weight and BMI in terms of direction and strength of association. Regarding gender predisposition, no association between any gender and changes in lipid profile was observed proven (P = 0.898).

Table 1

Correlation coefficients (r) compared to P values of different components of the lipid profile

Weight SDS (r) P	Log10 weight (kg) (r) P	BMI SDS (r) P	Log10 BMI (kg/m2) (r) P	Lipid profile variables
(0.253) 0.005	(−0.049) 0.493	(0.166) 0.082	(−0.018) 0.803	CHOL
(−0.111) 0.222	(−0.186) 0.009	(−0.171) 0.074	(−0.199) 0.007	HDL-C
(0.273) 0.003	(0.043) 0.554	(0.243) 0.012	(0.154) 0.038	LDL-C
(0.115) 0.217	(0.088) 0.220	(0.149) 0.129	(0.095) 0.200	TG

BMI=Body mass index, HDL-C=High-density lipoprotein-cholesterol, LDL-C=Low-density lipoprotein-cholesterol, CHOL=Cholesterol, TG=Triglycerides, SDS=Standard deviation score

DISCUSSION

CAD has been considered the greatest epidemic humankind has ever faced, of which obesity and dyslipidemia are two of the major contributors to its development.[19] More so, leading risk factors such as atherosclerosis and supporting lifestyles are found to generally begin in childhood and propagate further into adulthood.[132021] Therefore, to effectively bring about a prevention regimen into action, hyperlipidemia is to be identified and addressed at an earlier age. Further research was sought after to reveal more indicators of early lipoprotein dysfunction.[22] It is no longer of surprise that childhood dyslipidemia is alarmingly increased among the overweight and obese populations in comparison to those of normal weight population.[11] Studies such as that by Korsten-Reck et al. had managed to elucidate with evidence that abnormal lipid profiles were seen in as much as 45.8% of overweight children.[23] Dyslipidemia encompasses several disorders that show disturbed lipoprotein metabolism; increased levels in LDL-C, TGs, and total cholesterol; and decreased levels of HDL-C. A case–control study carried out in Turkey was investigating the credibility of BMI in predicting lipid profile abnormalities. Results of the aforementioned study of 100 children, 50 of which had a BMI above the 95th percentile for their age and gender compared to the other 50 children of normal BMI, revealed an increase in LDL-C levels among the obese groups.[15] Our study explains this finding by the positive association established between Log10 BMI kg/m2 and increase in LDL-C (P = 0.038). However, they report no difference of HDL-C levels seen between groups of high BMI and those of lower BMI. We, on the other hand, found an inversely proportional relationship between the mentioned variables. We report a negative association between the Log10 BMI kg/m2 and increases in HDL-C levels (P = 0.007). In addition, the HDL mean among those who disliked fast food was 1.5 ± 0.32, while the mean among those who favored it was 1.3 ± 0.3 (P = 0.001). Interestingly enough, no significant variation of both the mean of LDL-C (P = 0.134) and the mean of HDL-C (P = 0.250) was found among BMI categories, despite a noted increase of LDL-C seen in children with higher BMI values [Figure 1] and an increase in HDL-C in children with lower BMI values [Figure 2]. Contrarily, the log of BMI and cholesterol did manifest a significant variation among different BMI groups [Table 2], which is reinforced by the positive association that was found between weight SD scores and increased cholesterol.

Figure 1

Original. Mean plot: difference of the low-density lipoprotein-cholesterol mmol/L mean among body mass index levels

Figure 2

Mean plot: Difference of the High Density Lipoprotein cholesterol mmol/L mean among Body Mass Index levels

Table 2

Mean P value and standard deviation for the variation of different lipid profile components among the four body mass index categories based on a one-way analysis of variance

P	Morbidly obese	Obese	Overweight	Normal weight	Variables
0.0001	1.3674±0.04047	1.3664±0.04850	1.3099±0.07093	1.2551±0.05701	Log10 BMI (kg/m2)
0.050	4.3462±0.74542	3.9076±0.14781	3.5855±0.37149	3.9348±0.57696	CHOL
0.134	2.6688±0.37722	2.4225±0.61684	2.1592±0.62147	2.2983±0.47364	LDL-C
0.250	1.1700±0.29709	1.3129±0.27499	1.3633±0.27822	1.3916±0.30973	HDL-C

Log10 BMI=Logarithm of body mass index, HDL-C=High-density lipoprotein-cholesterol, LDL-C=Low-density lipoprotein-cholesterol, CHOL=Cholesterol

The WHO recognizes childhood obesity as a significant challenge of the 21st century as the number of overweight children under the age of 5 is projected to be more than 42 million.[24] Efforts had been directed toward identifying risk factors contributing to the spread of obesity in an attempt to combat the epidemic and promote awareness. Family history, unhealthy diets, low physical activity, sedentary lifestyles, urban residence, and higher socioeconomic statuses have all been found in association with obesity. In our study, no association between opposite genders and changes in lipid profile was proven (P = 0.898), concluding that a greater likelihood among one gender to develop obesity than the other is quite unlikely.

CONCLUSION

High BMI is associated with increased levels of LDL and cholesterol and decreased levels of HDL. Neither association with TG levels nor gender was established.

Thereby, we urge health-care providers and medical personnel, especially pediatricians who often interact with legal guardians and caretakers, to educate parents and family members on the substantial threats looming over childhood obesity, further encouraging their children to follow a healthier lifestyle and taking initiative by providing the necessary environment. This is essential even more so in Saudi Arabia, where conventional customs, habits, and regulations promote sedentary routines and precipitating diets.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form, the patients have given their consent for their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.