Relationship between some environmental factors and hyperbetalipoproteinemia in 6 - 11 year-old children in Hanoi

JOURNAL OF SCIENCE OF HNUE DOI: 10.18173/2354-1059.2016-0072 Natural Sci. 2016, Vol. 61, No. 9, pp. 185-192 This paper is available online at 185 RELATIONSHIP BETWEEN SOME ENVIRONMENTAL FACTORS AND HYPERBETALIPOPROTEINEMIA IN 6 - 11 YEAR-OLD CHILDREN IN HANOI Nguyen Thi Hong Hanh 1 , Bui Thi Nhung 2 , Le Thi Hop 2 and Tran Quang Binh 3 1 Faculty of Biology, Hanoi National University of Education 2 National Institute of Nutrition 3 National Institute of Hygiene and Epidemiology Abstract: Hyperbetalipoproteinemia is a risk of atherosclerosis and thrombosis, whichlead to a risk factor for coronary artery disease, hypertension, and stroke - the main causes of mortality globally. This study aimed to determine environmental factors associated with hyperbetalipoproteinemia in children in Hanoi. A case-control study was conducted with a sample of 420 children (41 children with hyperbetalipoproteinemia and 379 children without hyperbetalipoproteinemia) aged 6 to 11 years from primary schools in Hanoi. The results obtained by multi-variate logistic regression and Bayesian Model Averaging (BMA) analysis showed that the optimal predictive model of hyperbetalipoproteinemia in 6 - 11 year-old children in Hanoi included ‘appetite of eating eggs’, ‘caesarean delivery’, and ‘eating slowly’ factors. These findings suggested a reduction in consumption of eggs (less than 5 eggs/week), avoidance of caesarean delivery, and maintaining the ‘eating slowly’ habit to reduce the risk of hyperbetalipoproteinemia for 6 - 11 year-old children. Keywords: Environmental factors, hyperbetalipoproteinemia, 6 - 11 year-old children. 1. Introduction Hyperbetalipoproteinemia, elevated low density lipoprotein-cholesterol (LDL-C), is one of components of dyslipidemia. Hyperbetalipoproteinemia is the risk of atherosclerosis and thrombosis - leading risk factors for coronary artery disease, hypertension, and stroke - the main cause of mortality globally [1]. Nowadays, hyperbetalipoproteinemia is a great challenge for public health not only in developed but also in developing countries. It is alarming that the rate of hyperbetalipoproteinemia in children has been rising in recent years. This is proportional to the percentage of children with over-weight or obesity. In 2013, according to the results of the research on over-weight and obesity children at age of 4 - 9 years in Hanoi, the hyperbetalipoproteinemia prevalence was 12.6% [2]. Hyperbetalipoproteinemia in childhood can progress till adulthood and causes premature damage to children such as fatty liver, atherosclerosis [3]. Therefore, early detection of hyperbetalipoproteinemia in children will help prevent complications and reduce cardio-vascular risk in the future. Received June 27, 2016. Accepted November 26, 2016. Contact Nguyen Thi Hong Hanh, e-mail address: hanhphucmauhong111@yahoo.com Nguyen Thi Hong Hanh, Bui Thi Nhung, Le Thi Hop and Tran Quang Binh 186 Hyperbetalipoproteinemia is well-known as a multi-factorial disease which is influenced by gene-gene and gene-environment interactions. There are many environmental factors related to the plasma lipid profile, such as socio-economic status, diet and physical activity, and especially obesity [4]. However, in Vietnam, studies on the relationship between environmental factors and hyperbetalipoproteinemia in children are still limited. Therefore, this study aimed to determined which environmental factors related to hyperbetalipoproteinemia in 6 - 11 year-old children in Hanoi. An understanding of this relationship may provide new insights into target preventive intervention for coronary artery disease. 2. Content 2.1. Subjects and methods * Study subjects The study subjects aimed for primary school children in Hanoi, despite having no evidence of diseases related to atherosclerosis, CAD, diabetes and mental disorder. None of them was using lipid-lowering medication when their blood sample was taken. * Study design A case-control study was carried out from 2011 to 2012. Case group included 41 children with hyperbetalipoproteinemia, and control group included 379 children without hyperbetalipoproteinemia. The research protocol was approved by the Ethics Committee of the National Institute of Nutrition of Vietnam. Written consent to participate in the study was given by the parents of all subjects. Hyperbetalipoproteinemia was diagnosed according to the criteria of the National Cholesterol Education Program (NCEP) [5]. Hyperbetalipoproteinemia was defined as LDL-C  130 mg/dL. Children in control group had all lipid component levels in the normal ranges (TG < 70 mg/dL with children age under 10 years or TG  90 mg/dL with children age uper 10 years; TC < 170 mg/dL; HDL-C > 45 mg/dL; LDL-C < 110 mg/dL). * Measurements Blood lipids and lipoproteins were measured fast on samples obtained after an overnight. Blood samples were collected in EDTA containing tubes. Serum TC and TG were determined with enzymatic method. Serum HDL-C and LDL-C were measured through a direct assay. All determinations were performed with Auto-Analyzer (Type Architect C8000; Abbott Ltd., United States of America) in Medlatec Hospital of Hanoi City. A questionnaire was provided along with consent forms and parents were asked to provide information regarding their child’s general health, socio-economic status (food costs per person per month), neo-natal characteristics (babies delivery type, birth weight, weaning time, beginning time to take a punch, drinking formula milk during the first six months), dietary behaviors (gluttonous, eating fast/slowly, gorge, having sub- meal, appetite of eating eggs/sweet food/fatty food/fruits and vegetables), physical activity (exercises, means of transport to the school, total time forwatching television and playing computer games, nap time, night sleep duration). Relationship between some environmental factors and hyperbetalipoproteinemia 187 The body weight of participants was measured to the nearest 0.1 kg with standardized medical scales. Subjects were weighed without shoes and minimum of clothing. The height was measured to the nearest 0.1 cm. Body mass index (BMI) was calculated as weight divided by height squared (kg/m 2 ). Waist circumference was measured at the end of a normal expiration to the nearest 0.1 cm at the mid-point between the last floating rib and the top of the iliac crest. Hip circumference was measured at the level of the symphysis pubis and the greatest gluteal protuberance. Waist-to-hip ratio was calculated as waist circumference (in cm) divided by hip circumference (in cm). * Statistical analysis Qualitative variables were expressed as percentages. Quantitative variables were expressed as means ± SD if variables were normal distribution or median (inter-quartile range) if variables were not normal distribution. Chi-square test or independent-sample T test or Mann-Whitney U test were used when appropriate. The relationship between risk factors and hyperbetalipoproteinemia was tested by binary logistic regression analysis. Age, gender, and BMI were adjusted for the statistical analysis. Risk factor probability set for predictive models was calculated by Bayesian Model Averaging (BMA) analysis. The statistical analyses were done with the statistical software package SPSS 16.0 (SPSS Inc., Chicago, Illinois), and R 3.2.3 (https://www.r-project.org). A P-value of less than 0.05 was considered statistically significant. 2.2. Results and discussion 2.2.1. Characteristics of the study subjects Lipid profile and anthropo-metric characteristics of the subjects in case and control groups are presented in Table 1. There were significant differences between case and control groups in obese status, TG, TC, LDL-C, and TC/HDL-C (P < 0.05). There was no difference of gender, age, weight, height, BMI, waist circumference, waist to hip ratio, blood pressure, and HDL-C level between the two groups (P > 0.05). Table 1. Characteristics of the study subjects Parameter Controls (n = 379) Cases (n = 41) P Male (%) 73.4 71.4 0.870 Age (years) b 8.0 (7.1 - 9.1) 8.2 (7.4 - 9.0) 0.365 Weight (kg) b 30.6 (23.6 - 37.6) 34.9 (27.1 - 38.9) 0.394 Height (cm) a 127.3 ± 9.2 127.9 ± 7.0 0.819 Obesity (%) 34.3 61.5 0.027 BMI (kg/m 2 ) b 17.3 (15.0 - 22.0) 21.9 (16.3 - 23.1) 0.065 Waist circumference (cm) b 58.0 (51.8 - 69.6) 68.3 (55.5 - 72.8) 0.141 Waist to hip ratio a 0.89 ± 0.07 0.90 ± 0.72 0.548 Systolic blood pressure 110.6 ± 14.7 117.6 ± 9.4 0.206 Nguyen Thi Hong Hanh, Bui Thi Nhung, Le Thi Hop and Tran Quang Binh 188 (mmHg) a Diastolic blood pressure (mmHg) a 71.1 ± 12.7 78.4 ± 11.3 0.133 Triglyceride (mmol/L) b 62.8 (49.6 - 77.9) 89.8 (63.7 - 123.9) 0.001 Total cholesterol (mmol/L) a 144.7 ± 22.8 222.8 ± 30.6 < 0.0001 HDL-C (mmol/L) b 54.3 (47.2 - 63.0) 50.8 (46.3 - 55.2) 0.575 LDL-C (mmol/L) b 80.8 (71.9 - 94.4) 138.1 (134.4 - 174.5) < 0.0001 TC/HDL-C b 2.62 (2.33 - 3.06) 3.70 (3.27 - 4.11) < 0.0001 a Data are mean ± SD. b Data are median (interquartile range). P-values obtained by Student T test or Mann-Whitney U test or Chi-square test. Bold values indicate significant differences between cases and controls. BMI, body mass index; HDL-C, high-density lipoprotein-cholesterol; LDL-C, low-density lipoprotein-cholesterol; TC, total cholesterol 2.2.2. The relationship between some environmental factors and hyperbetalipoproteinemia in 6 - 11 years old children in Hanoi using logistic regression analysis All variables collected from the questionnaire were analyzed using logistic regression adjusted for age, gender and BMI. The variables related significantly to hyperbetalipoproteinemia are presented in Table 2. The analyzed results of relationship between some factors and hyperbetalipoproteinemia showed that ‘caesarean delivery’ and ‘appetite of eating eggs’ increased the hyperbetalipoproteinemia risk, and ‘eating slowly habit’ tended to reduce the hyperbetalipoproteinemia risk (Table 2). Table 2. The relationship between some environmental factors and hyperbetalipoproteinemia in 6 - 11 year-old children in Hanoi Characteristics OR (95%CI) P OR * (95%CI) P *  ± SE Neonatal characteristics Vaginal delivery 1 Caesarean delivery 3.4 (1.3 - 4.9) 0.049 3.3 (1.0 - 10.7) 0.046 1.19 ± 0.06 Dietary behaviors Eating normally 1 1 Eating slowly 0.1 (0.1 - 1.0) 0.065 0.2 (0.1 - 1.0) 0.052 -1.53 ± 0.07 Appetite of eating eggs (> 5 eggs/week) 5.2 (1.7 - 15.5) 0.003 7.5 (2.3 - 24.1) 0.001 2.01 ± 0.05 OR, P obtained after adjusted for age, gender and BMI. OR * , P * ,  obtained by multi-variate logistic regression. 95% CI (95% confidence interval) Our findings are consistent with the theory that caesarean delivery disrupts the normal bacterial colonization of the newborn. During vaginal delivery, the fetus is coated by and Relationship between some environmental factors and hyperbetalipoproteinemia 189 swallows bacterial strains from the maternal vaginal and gastro-intestinal tracts. Children who are delivered by caesarean section miss this normal source of bacterial colonization. Their intestines are colonized by micro-biota derived from contact with mothers’ skin, and from other sources [6, 7]. Therefore, caesarean delivery may affect the child's digestive system. Several studies have demonstrated that caesarean delivery is associated with increased body mass in childhood and adolescence [6]. Besides, caesarean delivery also affect the activities of endocrine glands, especially the thyroid hormone in children, which is related to dyslipidemia [8]. Eggs contains a natural source of folate, riboflavin, selenium, choline, vitamin B12, and fat- soluble vitamins A, D, E, and K. Eggs also provide high-quality, bio-available protein [9]. Thus, evidences suggest that eating less than 3 eggs/week results in a protective factor for cardiovascular disease [10]. In addition, some studies didn’t show the association between egg consumption with dyslipidemia [11]. However, egg, a concentrated source of cholesterol (one yolk provides ~215 mg of cholesterol), had been widely known as a risk factor of dyslipidemia and heart disease [12]. Data from some studies showed that consumption of more than 3 eggs per day adversely affect the lipid profile [13]. So, WHO recommended that children and adolescents should eat an average of 3 - 4 eggs/week to help provide essential protein and cholesterol for the children’s development. In our study, there was no relationship between residence, number of persons living in a household, food costs and hyperbetalipoproteinemia. Neo-natal characteristics including: birth weight, weaning time, beginning time to take a punch, and drinking formula milk during the first six months did not associate with hyperbetalipoproteinemia (P > 0.05). Some dietary behaviors (gluttonous, eating fast, gorge, having sub-meal, appetite of sweet food/fatty food/fruits and vegetables); physical activity (exercise, transport means to the school, total time of watching television and playing computer games, nap time, night sleep duration), and obesity-related traits (normal weight/obesity, BMI, waist circumference, hip circumference, waist to hip ratio, having overweight-obesity parents) did not associate with hyperbetalipoproteinemia (P > 0.05). The limitations of our study were that some simple and easily-collected variables used for primary school children may not accurately reflect the level of physical activity and diets of children. Thus, the association of these variables with hyperbetalipoproteinemia in primary school children in Hanoi was not found. Model Number of risk factor Age Gender Caesarean delivery Eating slowly Appetite of eating eggs PH-L test AUC 1 5 X X X X X 0.772 0.803 2 4 X X X X 0.768 0.822 3 3 X X X 0.253 0.814 Figure 1. Multi-variate logistic regression analysis model of the relationship between some environmental factors and hyperbetalipoproteinemia in 6 - 11 year-old children in Hanoi using backward conditional method Note. X: Yes; P obtained by Hosmer-Lemeshow test H-L: Hosmer-Lemeshow; AUC: Area Under the Curve Nguyen Thi Hong Hanh, Bui Thi Nhung, Le Thi Hop and Tran Quang Binh 190 To select the environmental factors associated to hyperbetalipoproteinemia for optimal prediction model, a backward conditional method was used. The results are show in Figures 1 and 2. Three models were selected when using backward conditional method. These three models had PH-L test > 0.05. Predictability of the three models was good with AUC range from 0.803 to 0.822. Figure 2. ROC graph in the model predictions of the relationship between some environmental factors and hyperbetalipoproteinemia in 6 - 11 year-old children in Hanoi In three selected models, predictability of the model 3 was 81.4% with three factors (caesarean delivery, appetite of eating eggs and ‘eating slowly’ habit). Therefore, this model is the optimal prediction for hyperbetalipoproteinemia in 6 - 11 year-old children in Hanoi. 2.2.3. The relationship between some environmental factors and hyperbetalipoproteinemia in 6 - 11 years old children in Hanoi using Bayesian Model Averaging analysis To evaluate the probability that risk factors set for the predictive models of hyperbetalipoproteinemia in 6 - 11 year-old children in Hanoi, we used Bayesian Model Averaging (BMA). BMA offers a coherent approach to accounting for model uncertainty. BMA has also been demonstrated to improve predictive performance, and to avoid the problem of over- statement of the strength of evidence - a problem when P-values are computed after traditional variable selection [14]. BMA is useful after a careful scientific analysis of the problem at hand. BMA offers one more tool in the toolbox of applied statisticians for improved data analysis and interpretation [15]. Figure 3. Predictive hyperbetalipoproteinemia models selected by BMA in children Blue: protective factor; Red: risk factor; right column: probability of factor in the predictive models Relationship between some environmental factors and hyperbetalipoproteinemia 191 Results of BMA analysis showed that probability that ‘appetite of eating eggs’, ‘caesarean delivery’ and ‘eating slowly’ factors were set for the predictive hyperbetalipoproteinemia models in children in Hanoi was 94.5%, 39.6% and 26.1%, respectively (Figure 3). This result showed that ‘appetite of eating eggs’, ‘caesarean delivery’, and ‘eating slowly’ factors were valuable in predicting hyperbetalipoproteinemia in 6 - 11 year-old children in Hanoi. 3. Conclusion The results obtained by multi-variate logistic regression and BMA analysis showed that the optimal predictive models of hyperbetalipoproteinemia in 6-11 year-old children in Hanoi included ‘appetite of eating eggs’, ‘caesarean delivery’ and ‘eating slowly’ factors. These findings suggest a reduction in consumption of eggs (less than 5 eggs/week), avoidance of caesarean delivery, and maintaining the ‘eating slowly’ habit to reduce the risk of hyperbetalipoproteinemia and heart disease for 6-11 year-old children. Acknowledgements. The authors would like to thank colleagues at the National Institute of Nutrition, and Hanoi National University of Education for their kind help and support. 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