Introduction

In recent years, the prevalence and mortality of cardiovascular disease in China are still on the rise, and the mortality rate of cardiovascular disease ranks first, which has become a major public health problem. Atherosclerosis is considered to be an independent risk factor for cardiovascular disease [1-3]. Relevant studies have shown that dyslipidemia in school-age children will not only present the risk of atherosclerosis in adolescence, but also continue to develop into adulthood, which increases the risk of cardiovascular disease in adulthood, and the severity is closely related to dyslipidemia [3-6]. Therefore, this study used the data of Beijing school-age children aged 6-17 years from the China Children and Lactating Women Nutrition and Health Surveillance (2016-2017) to analyze the prevalence of dyslipidemia and its influencing factors, and to provide scientific basis for the followup targeted intervention.

Materials and Methods Study Design and Samples

Data of Beijing school-age children aged 6-17 years were collected from China Child and Maternal Nutrition and Health Surveillance (2016-2017). A total of 841 students were enrolled. This study was approved by the Ethics Review Committee of Chinese Center for Disease Control and Prevention (ethical approval number: 2017-021). All the subjects and their guardians signed the informed consent, and the subjects had no recent infectious diseases.

Data Collection and Measurements

Data on demographic characteristics and related factors were collected by trained and qualified investigators from China Child and Lactating Women Nutrition and Health Surveillance 20162017. Body measurements (height, weight, waist circumference, blood pressure, etc.) were measured by measuring instruments (TZG height altimeter, Pelta HD-390 electronic weight scale, Omron HBP1300 electronic blood pressure monitor) designated by the national project group and repeated for 2 times. Laboratory test: 6ml fasting venous blood of the subjects was collected in the morning, placed in the dark for 30 minutes in a vacuum separation rubber tube, centrifuged at 1500×g at room temperature for 10-15 minutes, separated, transferred to a special light-proof frozen storage tube, placed in the light-proof frozen storage box, put in the frozen storage box, and stored at -70 ℃ until tested. All biochemical indicators were tested by qualified and certified laboratories which passed the quality assessment of the national Project Working group. Total cholesterol (TC), triglyceride (TG), high-density lipoprotein-cholesterol (HDL-C) were detected. High density lipoprotein-cholesterol (HDL-C), low-density lipoproteincholesterol (LDL-C), etc.

Definition and judgment criteria

According to the “Consensus on Prevention and treatment of Dyslipidemia in children and Adolescents” [7], hypercholesterolemia: TC≥5.18mmol/L; Hypertriglyceridemia: TG≥1.70mmol/L; Low HDL-C: HDL-C≤1.04 mmol/L; High LDL-C: LDL-C≥3.37mmol/L. Any of these conditions was defined as “dyslipidemia. Overweight and obesity: The overweight and obesity status of children aged 12-17 years was determined according to the screening criteria for overweight and obesity of school-age children and adolescents (Health industry standard of the People’s Republic of China WS/ T586-2018) [8].

Quality Assurance

From 2016 to 2017, the nutrition and health surveillance of children and lactating women in China was carried out in all monitoring points, including unified training, unified methods, unified standards, unified equipment, unified data entry and cleaning. Quality control groups were established at national, provincial and monitoring points, and their responsibilities and tasks were specified to be responsible for on-site inspection and supervision.

Statistical Analysis

Data cleaning and analysis were performed using SAS 9.4 software (SAS Institute Inc., Cary, NC, USA). Chi-square test was used to test the differences of dyslipidemia among different population characteristics. Logistic regression analysis was used to analyze the influencing factors. The test level α=0.05.

Results Sample size description

A total of 841 school-age children aged 6-17 years were included in this study, including 423 boys (50.3%) and 418 girls (49.7%). The average age of school-age children was 14.16±1.75 years.

Dyslipidemia in school children aged 6-17 years in Beijing

The prevalence of dyslipidemia among children aged 6-17 years in Beijing was 10.23%. The prevalence of hypercholesterolemia, hypertriglyceridemia, low HDL-C and high LDL-C was 5.83%, 5.11%, 3.57% and 3.92%, respectively. The detection rates of dyslipidemia, hyper TC, low HDL-C and high LDL-C in boys were higher than those in girls, and the detection rates of high TG in boys were lower than those in girls, with no statistical significance (P>0.05). The detection rates of dyslipidemia, hyper TC, hyper TG, low HDL-C and high LDL-C were the lowest in school-age children with normal weight, and the detection rates of dyslipidemia, high TG, and low HDL-C were the highest in school-age children with overweight. The detection rates of hyper TC and high LDL-C in obese school-age children were the highest, and the above differences (except hyper TC)

The results of this study showed that the detection rate of dyslipidemia in school-age children aged 6-17 years in Beijing (10.23%) was slightly higher than the results of Zhu Ying et al. ‘s study on dyslipidemia in children and adolescents aged 6-18 years in Beijing in 2004 (9.61%) [12]. This was lower than the results of dyslipidemia (20.3%) in Baseline characteristics of Cardiovascular and Bone Health Promotion Program for Children and Adolescents carried out by Hou Dongqing et al in four districts of Beijing in 2016 [13]. The reason for the big difference with the results of Hou Dongqing et al., may be related to the inconsistency of age range and regional distribution of the research objects. The age of the object of this research is uniformly distributed in 6 - 17 years old and in Beijing dongcheng, chaoyang, changping and shunyi and yanqing dis-trict, and studies such as Hou Dongqing select only part of that age students elementary school, junior high school grade 1 - 4 grade and high school grade one students as the research object and in Beijing dongcheng district of, well, miyun and carried out.

The results of this study showed that there were significant differences in the detection rate of dyslipidemia among school-age children aged 6-17 in different areas of Beijing. Taking Changping District (suburb) as reference, the detection rate of dyslipidemia in school-age children aged 6-17 in Dongcheng district (urban area) was 2.91 times that of Changping District, and the detection rate in Shunyi District (suburb) was 2.74 times that of Changping District. However, there was no statistically significant difference between the detection rate in Chaoyang District (urban area) and Yanqing District (suburb) and Changping District (suburb) respectively. The possible reasons are related to the different location, socioeconomic and cultural level, dietary structure, dietary habits and lifestyle of each district in Beijing.

The results of this study showed that overweight and obese school-age children had a 2.55 times higher risk of dyslipidemia than those with normal weight, indicating that overweight and obesity are risk factors for dyslipidemia in children and adolescents, which is consistent with the results of related studies [9, 10, 12-15]. In the past 20 years, the obesity rate of children and adolescents in China has shown a rapid increase. A series of metabolic abnormalities and chronic inflammation caused by childhood obesity can have negative effects on multiple organs and systems of the body, including cardiovascular metabolic diseases such as hypertension, hyperglycemia and dyslipidemia. Therefore, the current government, schools and families should pay attention to the overweight and obesity of school-age children, and rationally balance diet and eating activity according to the Dietary Guidelines for School-age Children in China (2022), so as to avoid the occurrence of obesity and reduce the risk of cardiovascular and metabolic diseases such as dyslipidemia.

Conclusions

In conclusion, the prevalence of dyslipidemia is high in school-age children aged 6-17 years in Beijing, and overweight and obesity are the risk factors for dyslipidemia, and the regional differences are obvious. Relevant departments should pay great attention to it and actively carry out effective intervention measures.

Author Contributions: L.H., X.W. drafted the manuscript and carried out statistical analyses. Y.S. supervised the study process. B.Y.investigated and collected information; Y.Y., R.T., Y.Z. carried out the critical review of the manuscript. All authors have read and agreed to the published version of the manuscript.

Institutional Review Board Statement: The study was conducted according to the guidelines of the Declara-tion of Helsinki, and approved by the Ethics Committee of Chinese Center for Disease Control and Prevention (protocol code 2017-021).

Informed Consent Statement : Informed consent was obtained from all subjects involved in the study.

Data Availability Statement: The data presented in this study are non-public.

Acknowledgments: We thank the CDC of Dongcheng District, Chaoyang District, Changping District, Shunyi District, Yanqing District and related staff for their support and help in the investigation.

Conflicts of Interest: The authors declare no conflict of interest.

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