Conicity index as an indicator of body fat percentage in adolescents

Abstract

New indicators have been proposed in order to detect obesity and body fat distribution, such as conicity index (CI). The previous study found that CI has a significant correlation with high body fat in adolescents. This study aimed to assess the association of Conicity Index (CI) with Body Mass Index (BMI) and Body Fat Percentage (%BF) and evaluated the accuracy of CI based on %BF as gold standard for identification of obesity in adolescents. This cross-sectional study consisted of 620 adolescents (283 boys and 337 girls) aged 14-18 years. The correlation was tested using Spearman analysis. Obesity was based on age-and-sex specific body fat percentage cut-off values of body fat reference curves for children from Growth Foundation. Receiver operating characteristic (ROC) curve analyses were used to assess the accuracy of CI as a diagnostic test of obesity in adolescents. This study showed that CI was significantly correlated with BMI (boys: r = 0.485, p<0.0001; girls: r = 0.302, p<0.0001) and %BF (boys: r = 0.544, p<0.0001; girls: r = 0.347, p<0.0001). The area under curve (AUC) of CI for the diagnostic of obesity were over 0.9 for boys and over 0.7 for girls. The cut-off values for defining obesity were 1.13 (Sensitivity (Se) and Specificity (Sp) > 0.8) for boys and 1.14 (Se and Sp > 0.6) for girls. In conclusion, CI positively associated with BMI and % BF. CI is more accurate in boys than girls for the screening of excess adiposity in adolescents.