ESPE Abstracts

Introduction: childhood obesity constitutes a relevant problem of public health. Body mass index (BMI) is the most used anthropometric parameter for its definition: >2 z-score deviation (SD) according to age and sex for reference charts. Recent studies have proposed triponderal mass index (TMI) to identify metabolic risk by obesity. TMI presents the advantage to be a constant value simplifying the calculations.

Aims: determine the usefulness of TMI as an identifier of childhood obesity (0-18 years).

Methods: demographic (age, sex) and anthropometric data (weight, size) of 58.354 clinical observations of 7.792 boys and girls, 0-18 years old, of the Pediatric-Endocrine Department of a Tertiary Hospital were avaluated. BMI (kg/m²), SD value for age and sex and TMI (kg/m³) were calculated. Sensitivity, specificity, VPP and VPN for the values of TMI according to the values BMI-SD z score (<2, 2-3, 3-4, 4-5, >5 SD) for sex were calculated. Two groups of age (<8 years and 8-18 years) were defined. UAC curve was used to determine the optimum cut-off point that maximizes the sensitivity and specificity of TMI in relation to the BMI z-score value.

Results: of 58.354 observations, 45.57% correspond to the <8 years group (42.62% boys, 57.40% girls) and 54.44% to the 8-18 years group (48.61% girls, 51.38% boys). In 8-18 years group a positive linear relation (r >0,95) was obtained between the BMI z score- value and TMI. For the < 8 years we did not observe this relation (r < 0,4). In children 8-18 years old, TMI point that correlates better with BMI-SD values was: 17.08, 18.90, 19.94, 21.36 for BMI(SD)<=2, 2<BMI(SD)<=3, 3<BMI(SD)<=4, BMI (SD)>4 for boys and 16.87, 18.48, 19.64, 21.18 for girls respectively. The AUC curve and the confidence interval for each TMI value are shown in attached table.

Conclusions: -TMI presents a strong linear correlation with BMI-SD values in children 8-18 years old -TMI allows to describe the obesity degree easier. -In children <8 years the relation between both variables does not seem to be so useful