Neck circumference and excess weight: proposal of cutoff points for Brazilian adolescents.

OBJECTIVE: To indicate neck circumference (NC) cutoff points to identify excess weight at different stages of somatic maturation and evaluate the association between NC and body mass index (BMI). METHODS: Cross-sectional study with 1715 adolescents. BMI was classified according to the World Health Organization (WHO) criteria. Somatic maturation was obtained through the peak growth velocity (PGV). To define the cutoff points, curves of the receiver operating characteristic (ROC) model were constructed. The agreement between the anthropometric evaluation instruments was analyzed. The association between the variables was verified. RESULTS: Of the girls, 93 were in the pre-PGV stage, 266 in the PGV stage, and 481 in the post-PGV stage. Of the boys, 264 were in the pre-PGV stage, 334 in the PGV stage, and 277 in the post-PGV stage. For the pre-PGV group, the cutoff point was 28cm for females and 29cm for males; for the group during PGV, the cutoff points were 30cm for females and 33cm for males; in the post-PGV group the cutoff values were 32cm in females and 35cm in males. The prevalence of excess weight was higher in the pre-PGV stage in males and in the PGV stage in females. The correlation coefficients were higher in the pre-PGV and PGV stages. CONCLUSION: The cutoff points for NC found in this study showed good sensitivity and specificity to identify excess weight in Brazilian adolescents and can be used as a reference in epidemiological studies.