Percentiles for anthropometric measures in Iranian children and adolescents: the CASPIAN-IV study.

BACKGROUND The aim of the study was to provide the age- and sex-specific percentile values of anthropometric measures for Iranian children and adolescents. METHODS This cross-sectional nationwide survey was conducted on a representative sample of 14,880 school students, selected by multistage random cluster sampling from urban and rural areas of 30 provinces in Iran. Anthropometric measures including body mass index (BMI), waist circumference (WC), hip circumference (HC), and wrist circumference were measured under standard protocols by using calibrated instruments. Age- and gender-specific reference values were developed for anthropometric measures by the maximum penalized likelihood approach [Cole's least mean square (LMS) method]. RESULTS In the present study, 13,486 out of the 14,880 invited subjects completed all the required data of the study (participation rate: 90.6%). Participants consisted of 6640 girls (49.2%) and 75.6% urban residents; their mean and standard deviation (SD) age was 12.47±3.36 years. The BMI percentile curves of girls had a sharp increase from 14 to 18 years, and then began to plateau, but among boys, these curves had a consistent increase until the age of 18 years. In addition, the higher percentiles were higher in adolescent boys than girls. The HC percentile curves of both sexes had a persistent increase and the percentiles for HC were higher in adolescent girls than in boys. WC had a sharp increase from 7 to 18 years of age for boys, whereas for girls, these curves had a less sharp increase with age. In all ages, the percentiles for wrist circumference were higher in adolescent boys than girls. CONCLUSIONS The findings of this study highlight the necessity of paying special attention to developing age- and gender-specific percentiles of anthropometric measures in children and adolescents.