Reference curves of anthropometric indices in two national studies conducted among Iranian children in 2003-2004 and 2009-2010: The Caspian study

Background: Reference percentile curves are usually used as a screening tool to determine growth disorders. Anthropometric indices are population-dependent and may differ according to ethnicity, dietary pattern and lifestyle habits. This study aims to compare the curves of anthropometric measures obtained in two national studies conducted among Iranian children and adolescents in 2003-2004 and 2009-2010. Materials and Methods: Anthropometric measures obtained in two nationwide surveys conducted in 10-18-year-old Iranian students were compared. Lambda-mu-sigma (LMS) Chart Maker Pro program was used to develop age- and gender-specific percentiles and to smooth and fit the model. Results: In 2003-2004, the mean and standard deviation (SD) of body mass index (BMI) and waist circumference (WC) were 18.98 ± 3.81 kg/m2 and 67.50 ± 11.05 cm in boys; and 19.44 ± 3.78 kg/m2 and 66.55 ± 9.89 cm in girls, respectively. In 2009-2010, the corresponding figures were 19.16 ± 4.07 kg/m2, 69.42 ± 11.43 cm, 19.63 ± 4.11 kg/m2, and 67.29 ± 9.69 cm, respectively. Height curves did not show considerable changes in two studies. Comparison of two series of studies showed that the weight, BMI, WC, and waist-to-height ratio were lower in adolescent girls than boys especially in higher percentiles. Moreover, in both genders, weight, BMI, and WC percentiles decreased. Conclusion: The growth charts of Iranian children and adolescents aged 10-18 years have changed over 5 years. The reference growth curves change over time in the pediatric age group, repeated surveys should be conducted to update the age- and gender-specific reference curves in different populations.