Abdominal circumference as an indicator of clinical and laboratory parameters associated with obesity in children and adolescents: comparison between two reference tables.

Objective: To evaluate the sensitivity and specificity of two pediatric abdominal circumference reference tables to detect abnormally high body mass index, total cholesterol, fasting blood insulin and leptin levels, and homeostasis model assessment values.

Methods: A total of 624 male and female subjects, with ages ranging from 7 to 18 years, were evaluated. All children were recruited from two public schools. Venous blood samples were collected for determination of fasting plasma insulin, glucose, leptin, and total cholesterol levels. Weight, height and abdominal circumference were assessed according to internationally accepted guidelines. Contingency tables were constructed, comparing the presence or absence of increased abdominal circumference, according to cutoff points established by Taylor et al. and Freedman et al., with the presence or absence of abnormal values in the laboratory tests.

Results: Sensitivity values were consistently higher for the table by Taylor et al., whereas the table by Freedman et al. showed greater specificity. Positive predictive values were quite low in general, and were only relevant for body mass index.

Conclusions: Results indicate that the table by Taylor et al. is best for screening purposes, as it identifies individuals at higher risk of presenting abnormal test results. On the other hand, the reference table by Freedman et al. is more suitable for clinical practice, as it could be used to replace laboratory measurements, such as blood insulin or leptin levels, which may not be available at all sites.