Alexis E Malavazos1, Gloria Capitanio2, Valentina Milani3, Federico Ambrogi4, Irene A Matelloni2, Sara Basilico2, Carola Dubini2, Francesca M Sironi2, Elisabetta Stella2, Silvana Castaldi5, Francesco Secchi6, Lorenzo Menicanti3, Gianluca Iacobellis7, Massimiliano M Corsi Romanelli8, Michele O Carruba9, Lelio F Morricone2. 1. Endocrinology Unit, Clinical Nutrition and Cardiovascular Prevention Service, IRCCS Policlinico San Donato, San Donato Milanese, Italy. Electronic address: alexis.malavazos@gmail.com. 2. Endocrinology Unit, Clinical Nutrition and Cardiovascular Prevention Service, IRCCS Policlinico San Donato, San Donato Milanese, Italy. 3. Scientific Directorate, IRCCS Policlinico San Donato, San Donato Milanese, Italy. 4. Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy. 5. Department of Biomedical Sciences for Health, University of Milan, Milan, Italy. 6. Department of Biomedical Sciences for Health, University of Milan, Milan, Italy; Radiology Unit, IRCCS Policlinico San Donato, San Donato Milanese, Italy. 7. Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, University of Miami, FL, USA. 8. Department of Biomedical Sciences for Health, University of Milan, Milan, Italy; U.O.C. SMEL-1 of Clinical Pathology, IRCCS Policlinico San Donato, San Donato Milanese, Milan, Italy. 9. Department of Medical Biotechnology and Translational Medicine, Center for Study and Research on Obesity, University of Milan, Milan, Italy.
Abstract
BACKGROUND AND AIMS: Recently, it has been hypothesized that Tri-Ponderal Mass Index (TMI) may be a valid alternative to Body Mass Index (BMI) when measuring body fat in adolescents. We aimed to verify whether TMI has better accuracy than BMI in discriminating central obesity and hypertension in adolescents with overweight. METHODS AND RESULTS: This monocentric and retrospective cross-sectional study included 3749 pupils, 1889 males and 1860 females, aged 12-13. BMI (kg/m2) was calculated and expressed as percentiles and as z-scores. TMI (kg/m3) was calculated, and we used pre-defined cut-off previously proposed by Peterson et al.. For central obesity we adopted the Waist-to-Height Ratio (WHtR) discriminatory value of 0.5. Hypertension was defined as blood pressure ≥95th percentile of age- sex-, and height-specific references recommended by NHBPEP Working Group. The discriminant ability of TMI, BMI and BMI z-score, with respect to central obesity and hypertension, was investigated using non-parametric receiver operating characteristic analysis. The overall misclassification rate for central obesity was 8.88% for TMI vs 14.10% for BMI percentiles and vs 14.92% for BMI z-scores (P < 0.001). The overall misclassification rate for hypertension was 7.50% for TMI vs 22.03% for BMI percentiles and vs 25.19% for BMI z-scores (P < 0.001). CONCLUSION: TMI is a superior body fat index and it could discriminate body fat distribution more accurately than BMI. This supports the use of TMI, in association with WHtR, to characterize adolescents with overweight and high cardio-metabolic risk. Our analysis needs to be extended to other ethnic groups and replicated in a wider age range and in longitudinal studies.
BACKGROUND AND AIMS: Recently, it has been hypothesized that Tri-Ponderal Mass Index (TMI) may be a valid alternative to Body Mass Index (BMI) when measuring body fat in adolescents. We aimed to verify whether TMI has better accuracy than BMI in discriminating central obesity and hypertension in adolescents with overweight. METHODS AND RESULTS: This monocentric and retrospective cross-sectional study included 3749 pupils, 1889 males and 1860 females, aged 12-13. BMI (kg/m2) was calculated and expressed as percentiles and as z-scores. TMI (kg/m3) was calculated, and we used pre-defined cut-off previously proposed by Peterson et al.. For central obesity we adopted the Waist-to-Height Ratio (WHtR) discriminatory value of 0.5. Hypertension was defined as blood pressure ≥95th percentile of age- sex-, and height-specific references recommended by NHBPEP Working Group. The discriminant ability of TMI, BMI and BMI z-score, with respect to central obesity and hypertension, was investigated using non-parametric receiver operating characteristic analysis. The overall misclassification rate for central obesity was 8.88% for TMI vs 14.10% for BMI percentiles and vs 14.92% for BMI z-scores (P < 0.001). The overall misclassification rate for hypertension was 7.50% for TMI vs 22.03% for BMI percentiles and vs 25.19% for BMI z-scores (P < 0.001). CONCLUSION: TMI is a superior body fat index and it could discriminate body fat distribution more accurately than BMI. This supports the use of TMI, in association with WHtR, to characterize adolescents with overweight and high cardio-metabolic risk. Our analysis needs to be extended to other ethnic groups and replicated in a wider age range and in longitudinal studies.