Abstract: Background：Neck circumference is a new anthropometric measurement parameter in recent years. However, there is no published study on the reference standard values and the growth charts of neck circumference for children and adolescents in China. Objective：To establish the reference standard values of neck circumference of children and adolescents aged 3-16 years and then to explore the cut-off values of neck circumference in predicting abdominal obesity in children and adolescents so as to provide a new index and reference for the clinical application of physical assessment in children and adolescents. Design：A cross-sectional study. Methods：The subjects were children and adolescents aged 3-16 years who underwent physical examination in the Children's Health Clinic of the Children's Hospital Affiliated to Nanjing Medical University from July 2021 to September 2022. Children with diseases that may affect neck circumference, growth and development, or limb disability, abnormal posture, or deformity were excluded. The neck circumference, height, weight, waist circumference and body composition were measured by 3 surveyors strictly according to the operating manual which was made by ourselves. Ten percent of samples were randomly selected for repeated verification, and the coincidence rate before and after verification should be ≥99%. Double track entry and logical check were carried out for data entry and arrangement. The neck circumference reference standard values of children and adolescents aged 3-16 years were established according to gender and age groups, and the growth charts were constructed by Lambda-median-sigma (LMS) method. Abdominal obesity was defined as waist-to-height ratio (WHtR) >0.48 in boys aged 6-16 years and girls aged 6-9 years, and WHtR >0.46 in girls aged 10-16 years. The association of neck circumference with other physical measures and abdominal obesity was analyzed. The area under the receiver operating characteristic (ROC) curve was used to analyze the accuracy of neck circumference reference in predicting abdominal obesity. Main outcome measures：The reference standard values of neck circumference for children and adolescents aged 3-16 years and the cut-off values of neck circumference for assessing abdominal obesity for children and adolescents aged 6-16 years. Results：A total of 18 371 children and adolescents aged 3-16 years were included in the analysis, including 10 701 boys (58.2%) and 7 670 girls. There were 5 407 (29.4%) children with abdominal obesity. In addition to body fat mass, neck circumference, age, height, weight, BMI, waist circumference, WHtR, skeletal muscle and skeletal muscle percentage (PSM) of boys were significantly greater than those of girls, body fat percentage (PBF) of girls was greater than that of boys, and the differences were statistically significant (all P<0.05). The neck circumference of boys and girls aged 3-16 years increased with age, and the neck circumference of boys was always greater than that of girls at each age. The average growth rate was 0.85 cm/year for boys and 0.65 cm/year for girls, which was similar for boys and girls aged 7 to 8 years. The annual growth rate of boys was greater than that of girls before the age of 7 and after the age of 8, and it was more obvious after the age of 12. For boys and girls, neck circumference was positively correlated with abdominal obesity (r male=0.614, r female=0.541), BMI (r male=0.824, r female= 0.800), waist circumference (r male=0.827, r female=0.801), WHtR (r male=0.729, r female=0.683) and PBF (r male=0.669, r female=0.679), and was negatively correlated with PSM (r male=-0.497, r female=-0.470). The optimal cut-off values of neck circumference for assessing abdominal obesity were 27.15-37.05 cm for boys and 26.25-30.50 cm for girls aged 6-16 years, both of which were located in the P75 of all gender and age groups. The area under the curve(AUC) of neck circumference in assessing abdominal obesity were ≥0.83 in boys and ＞0.79 in girls of all ages. Conclusions：The neck circumference of boys was greater than that of girls in all age groups and it increased with age from 3 to 16 years old. The optimal cut-off values of neck circumference for assessing abdominal obesity were 27.15-37.05 cm for boys and 26.25-30.50 cm for girls aged 6-16 years, and the AUC was≥0.83 in boys and ＞0.79 in girls of all ages, with high accuracy.

Key words: neck circumference, Waist circumference, Children, Adolescents, Abdominal obesity, Reference standard values