original article 1 Department of Pediatrics, Child Tri-ponderal mass index and Growth and Development Research Center, Research Institute for Primordial Prevention of Non-Communicable body mass index in prediction of Disease, Isfahan University of Medical Sciences, Isfahan pediatric metabolic syndrome: 2 Department of Pediatrics, Child Growth and Development Research Center, Research Institute for Primordial the CASPIAN-V study Prevention of Non-Communicable Disease, Isfahan University of Medical Sciences, Isfahan, Iran 3 Non-Communicable Diseases Research Mehri Khoshhali1 Center, Alborz University of Medical https://orcid.org/0000-0002-2883-8652 Sciences, Karaj, Iran, Endocrinology and Metabolism Research Center, Motahar Heidari-Beni2 https://orcid.org/0000-0001-5543-5536 Endocrinology and Metabolism Clinical Sciences Institute, Tehran University Mostafa Qorbani3,4 of Medical Sciences, Tehran, Iran https://orcid.org/0000-0001-9465-7588 4 Department of Epidemiology, Mohammad Esmaeil Motlagh5 Non-Communicable Diseases https://orcid.org/0000-0002-6101-548X Research Center, Endocrinology, and Metabolism Population Sciences Hasan Ziaodini6 Institute, Tehran University of https://orcid.org/0000-0002-7421-0196 Medical Sciences, Tehran, Iran Ramin Heshmat7 5 Department of Pediatrics, https://orcid.org/0000-0002-8134-7940 Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran 8 Roya Kelishadi 6 Health Psychology Research Center, https://orcid.org/0000-0001-7455-1495 Education Ministry, Tehran, Iran 7 Chronic Diseases Research Center, Endocrinology and Metabolism Population ABSTRACT Sciences Institute, Tehran University Objective: Body mass index (BMI) and tri-ponderal mass index (TMI) are anthropometric measures to of Medical Sciences, Tehran, Iran 8 evaluate body adiposity in the various age groups. The present study aims to compare the predictive Department of Pediatrics, Child Growth and Development Research value of TMI and BMI for metabolic syndrome (Mets) in children and adolescents of both genders. Center, Research Institute for Primordial Subjects and methods: A cross-sectional study conducted on 3731 Iranian children and adolescents Prevention of Non-Communicable aged 7-18 years obtained from the fifth survey of ‘Childhood and Adolescence Surveillance and Disease, Isfahan University of Prevention of Adult Non-communicable Disease’ (CASPIAN-V) study. The predictive value of BMI and Medical Sciences, Isfahan, Iran TMI for MetS were determined using Receiver-operator curves. Logistic regression analysis was used to assess the relationship between these indices with MetS. Results: 52.6% of participants were boys. The Correspondence to: mean (standard deviations) age for boys and girls were 12.62 (3.02) and 12.25 (3.05) years, respectively. Roya Kelishadi Department of Pediatrics, In boys, the area under the curve (AUC) of TMI was greater than BMI for all age groups. AUC of TMI was Child Growth and Development also greater than BMI for age group of 11-14 years (AUC = 0.74; 95% CI (0.67, 0.81)) in girls. Furthermore, Research Center, Research Institute for Primordial our findings showed that odds ratio of Mets for TMI was greater than BMI in age groups of 11-14 years Prevention of Non-communicable (OR = 1.33 vs 1.22) and 15-18 years (1.16 vs 1.15) in girls and boys, respectively. Conclusion: TMI and Disease, Isfahan University of Medical Sciences, BMI had moderate predictive value for identifying MetS. However, TMI was a better predictor of MetS Isfahan, Iran than BMI in both genders, especially in age groups of 11-14 and 15-19 years for girls and boys. Arch [email protected] Endocrinol Metab. 2020;64(2):171-8 Received on July/30/2018 Keywords Accepted on Mar/29/2019 Metabolic syndrome; body mass index; tri-ponderal mass index; pediatric DOI: 10.20945/2359-3997000000206 INTRODUCTION among children and adolescents in 2012 (4). Previous etabolic syndrome (MetS) is defined as a cluster studies indicated that MetS is a common metabolic Mof cardio metabolic risk factors, including central disorder among Iranian children (5-8). A systematic obesity, glucose intolerance, dyslipidemia and raised review reported prevalence rates of MetS in the range blood pressure (1). MetS can occur from early life (2). of 1-22% in Iran (9). During last decades, MetS has become a major health Obesity and overweight in childhood and problem in children and adolescents; because of various adolescence have emerged as one of the most factors including epidemiologic transition, double important public health concerns in the 21st century burden of nutritional disorders, and lifestyle changes. (10). It is important to determine the optimal weight- MetS is not limited to developed countries (3). height indices, which are closely correlated with weight AE&M all rights reserved. A systematic review determined the worldwide but uncorrelated with height across the growing © prevalence rates of MetS ranged between 0 and 19.2% period (11). Several studies determined that the body Copyright Arch Endocrinol Metab. 2020;64/2 171 TMI and BMI in predicting pediatric MetS mass index (BMI: body weight (kg)/height2 (m2)) The study population consisted of students aged is a preferable index in preschool children and adult 7-18 years in primary and secondary schools in (12-14). Furthermore, tri-ponderal mass index (TMI: urban and rural areas across the country. They were body weight (kg)/height3 (m3)) may be applicable selected using multistage stratified cluster sampling for newborns (15). Traditionally, the ponderal index method. Sampling within each province was conducted was devised in 1921 by Rohrer and cols. (16). It was according to the student’s place of residence (urban or originally suggested as a corpulence index and has been rural) and level of education (primary and secondary) used as an indicator of fetal nutrition. Several studies using the proportional to size method and with equal showed that the accuracy of TMI is higher than BMI to sex ratio. 4200 students were randomly selected for determine adiposity in infants (17,18). blood sampling. The general trend of Power (p) in Weight/Height p by age and gender was specified. However, trends of Physical measurements p are still not clear due to population differences in the A team of trained health care experts recorded studies (14). Recently, Peterson et al showed that TMI information based on approved check lists; they estimated body fat percentage more accurately than performed the examinations under standard protocols BMI in adolescents aged 8 to 17 years (19). Another by using calibrated instruments. Weight was measured study reported reference values of BMI and TMI for age for healthy non-underweight, non-obese millennial on a scale placed on a flat ground to the nearest 0.1 kg children in the Barcelona longitudinal growth study while subjects wearing a light cloth, and height were (1995-2017) (20). measured without shoes to the nearest 0.1 cm (28). The anthropometric measures are reliable, low BMI was calculated by dividing weight (kg) to height 2 cost, non-invasive and can be performed without squared (m ) and TMI was calculated dividing weight 3 highly technologic equipment by staff with minimal (kg) to height cubed (m ). Waist circumference (WC) training (21). Many studies have indicated association was measured using a non-elastic tape at a point midway between anthropometric measures with MetS and between the lower border of the rib cage and the iliac its components in children and adolescents (22-25). crest at the end of normal expiration to the nearest 0.1 However, to our knowledge, there is only one study cm (29). that explored thresholds of gender-specific TMI and Blood pressure was measured in the sitting position FMI ((fat mass)/height3) for the prediction of MetS in on the right arm using a mercury sphygmomanometer population of Colombian children and youth (26). The with an appropriate cuff size. It was measured 2 times purposes of this study were (a) to compare predictive at 5-min intervals; systolic and diastolic pressures were ability of TMI and BMI for the prediction of Mets recorded and the average was registered (30). among a large population of Iranian children and adolescents and (b) to determine the optimal cutoff Blood sampling values for BMI and TMI by gender and age groups. Fasting blood samples were obtained from students after 12–14 h of overnight fast. Fasting blood glucose METHODS AND MATERIALS (FBG), triglycerides (TG), total cholesterol (TC), low-density lipoprotein-cholesterol (LDL-C) and Study design and sample high-density lipoprotein-cholesterol (HDL-C) were measured enzymatically by Hitachi auto148 analyzer The data of this nationwide cross-sectional study were (Tokyo, Japan) (31,32). collected as a part of the “National survey of school student high risk behaviors” (2014-2015), as the MetS components fifth survey of the school-based surveillance system entitled Childhood and Adolescence Surveillance Subject were classified as having MetS, if they had at and PreventIon of Adult Non-communicable Disease least three of the following criteria according to the (CASPIAN-V) study. This school-based nationwide Adult Treatment Panel III (ATP III) criteria modified health survey was conducted in 30 provinces in Iran. for the pediatric age group (33). AE&M all rights reserved. © Details on the study protocol have been explained 1) Abdominal obesity was defined as waist-to- Copyright before (27) and here we report it in brief. height ratio equal to or more than 0.5 (34). 172 Arch Endocrinol Metab. 2020;64/2 TMI and BMI in predicting pediatric MetS 2) Elevated FBG ≥ 100 mg/dL. The association between TMI, BMI and their z-score 3) High serum TG ≥ 100 mg/dL. with risk of MetS was evaluated using logistic regression 4) Low serum HDL-C < 40 mg/dL (except in boy model by gender and age. The results of logistic 15-18 y in whom the cut-off was < 45 mg/dL) regression are presented as odds ratio (OR) and 95% (35).