Neck Circumference Percentiles of Iranian Children and Adolescents: The Weight Disorders Survey of CASPIAN IV Study

BACKGROUND: Neck circumference (NC), emerging as a key morphological index for pediatric obesity, is associated with obesity- and overweight-related detrimental conditions in children. In this study, we aimed to provide the age- and sex-specific percentile reference values for neck circumference of the Iranian children and adolescents. METHODS: We used the data gathered through the weight disorders survey of CASPIAN IV study conducted in 2011 - 2012 in Iran, including a total of 21954 Iranian children and adolescents, composed of 10750 girls and 11204 boys, aged 7 - 18 years old. We presented the interval of NC percentile in three age groups of 7 - 10 years, 11 - 14 years, and 15 - 18 years. Finally, age-specific nomograms of NC for both genders in the Iranian and Canadian populations were compared. RESULTS: The intervals of 90th percentile of NC for boys in the three periods of school age (7 - 10 years), pre-adolescence (11 - 14 years), and adolescence (15 - 18 years) were 24.2 - 30.0 cm, 26.6 - 33.2 cm, and 30.1 - 38.5 cm, respectively. These intervals for girls were 23.7 - 30.1 cm, 26.5 - 33.7 cm, and 28.5 - 36.0 cm, respectively. NC increased with age in both boys and girls and its variability showed an increasing trend with age. CONCLUSIONS: We demonstrated for the first time the NC reference values for the Iranian children and adolescents aged 7 - 18 years old. Considering the significant differences between our national NC references and the values reported from the Canadian population, it seems logical to use these national percentiles not only for epidemiologic studies but also for routine clinical examinations.