MULT: A new BMI reference to assess nutritional status of multi-ethnic children and adolescents

Accuracy of the international growth charts to diagnose obesity according to the body composition analysis in US children and adolescents

This study verified the accuracy of the international BMI references and the allometric BMI reference to diagnose obesity in children and adolescents from the USA. Data from 17 313 subjects were obtained from the National Health and Nutrition Examination Survey between the years 1999-2006 and 2011-2018. Fat Mass Index, Allometric Fat Mass Index and fat mass/fat-free mass were calculated. Receiver operating characteristic curve, AUC, sensitivity, specificity, positive likelihood ratio and negative likelihood ratio were estimated to evaluate the accuracy of the growth references for diagnosing obesity. The International Obesity Task Force, MULT BMI 17 years, MULT BMI 18 years and allometric BMI 19 years achieved the best sensitivity-specificity trade-off for boys, with sensitivities ranging from 0·92 to 0·96 and specificities of 0·94, with positive likelihood ratio of 15·51, 16·17, 13·46 and 18·01, respectively. The negative likelihood ratios were notably low, ranging from 0·04 to 0·08. In girls, the International Obesity Task Force, MULT BMI 17 years and MULT allometric BMI 17 years also demonstrated high sensitivity (0·95-0·97) and specificity (0·92), with positive likelihood ratio values of 11·54, 11·82 and 11·77, respectively and low negative likelihood ratio values (0·03-0·05). In summary, these international growth references presented satisfactory performance to diagnose obesity. However, the MULT growth reference performed better, and the MULT allometric BMI was the only indicator capable of detecting that girls have a higher proportion of fat mass than boys for the same index values. These findings suggest that the MULT growth reference may be a better tool to assess the nutritional status of children and adolescents internationally.

MULT: An allometric body mass index (ABMI) reference to assess nutritional status of multiethnic children and adolescents

OBJECTIVES

To develop an allometric body mass index (ABMI) reference that adjusts the weight in relation to height, taking into account the changes during development (MULT ABMI reference), and to compare it with international BMI references.

METHODS

The MULT ABMI reference was constructed through the LMS method, calculated with 65 644 ABMI observations of 17 447 subjects aged 5-22 years, from the United Kingdom, Ethiopia, India, Peru, Vietnam, Portugal, and Brazil. The M, S, and L curves of the MULT ABMI reference were compared with the curves of the MULT, World Health Organization (WHO), Centers for Disease Control and Prevention (CDC), International Obesity Task Force (IOTF), and Dutch Growth Study (DUTCH).

RESULTS

The greater differences in the M curve between MULT ABMI and WHO, CDC, IOTF, DUTCH, and MULT BMI references were around puberty (138 to 150 months for boys; 114 to 132 for girls). MULT ABMI presented S values similar to IOTF and DUTCH BMI references for boys 60 to 114 months and then became higher, approaching the MULT BMI S values from 198 to 240 months. For girls the MULT ABMI S values were close to the IOTF, CDC, and DUTCH from 60 to 110 months, and then became higher, approaching the MULT BMI S values until 240 months.

CONCLUSION

MULT ABMI presented an advantage in comparison to the existing BMI references because it takes into account the growth changes during puberty and is a new option to assess the nutritional status of multiethnic populations.

The Similarity Degree of the Anthropometric and Body Composition Variables of Brazilian and Mozambican Schoolchildren: A New Approach Using the Smoothed Jaccard Index Surface

BACKGROUND/OBJECTIVES

Brazil and Mozambique face similar socioeconomic challenges, including common indicators of undernutrition and overnutrition among children. This study evaluated the similarity degree of the anthropometric and body composition variables of Brazilian and Mozambican children by using the Jaccard index.

METHODS

A total of 1831 children of both genders aged 7-10 years from three Brazilian cities (Recife, Vitoria de Santo Antao, and Lagoa do Carro) and three Mozambican cities (Maputo, Boane, and Inhambane) participated in this study. Anthropometric (height, body mass, and waist circumference) and body composition (body fat percentage [%BF], lean mass, and fat mass) variables were measured and the Smoothed Jaccard Index Surface (SJIS) was used to evaluate the similarity degree.

RESULTS

Brazilian children were taller and heavier and had a higher %BF and fat mass than Mozambican children. Children living in urban areas were taller than those living in rural zones in both countries. Brazilian and Mozambican children showed high similarity only between %BF and lean mass. Children from Recife and Maputo had high similarities among waist circumference, body mass, fat mass, height, and %BF. Finally, a high SJIS degree was observed among height and %BF for schoolchildren from rural and urban zones.

CONCLUSION

Brazilian and Mozambican children exhibit differences in growth characteristics but a high degree of similarity when children from rural and urban zones are compared.

Comparison of international height and BMI-for-age growth references and their correlation with adiposity in Brazilian schoolchildren

This study verified the diagnostic accuracy of the nutritional status classified by the international height and BMI references of the World Health Organization (WHO) (WHO/2007), International Obesity Task Force (IOTF/2012) and MULT (2023). The data pool was composed by 22 737 subjects aged five to 16 years from the Santos and Porto Alegre surveys. A correlation matrix between the z-scores of the BMI references and the skinfold measurements was calculated through the Pearson correlation coefficient (r), and the subject's nutritional status was classified according to the international growth references. The accuracy for diagnosing obesity was performed separately by sex and using the 95th percentile of the triceps and subscapular skinfold sum, while Lin's concordance coefficient, Bland-Altman method and the Cohen's Kappa coefficient (Kappa) were used to verify the concordance and reliability among the BMI references. The correlation matrix showed a high positive correlation among the BMI z-scores (r ≥ 0·99) and among the skinfold measurements (r ≥ 0·86). The prevalence of stunting was higher when applying the MULT reference (3·4 %) compared with the WHO reference (2·3 %). The Bland-Altman plots showed the lowest critical difference (CD) between the height references of WHO and MULT (CD = 0·22). Among the BMI references, the WHO obesity percentile presented lower performance than MULT for boys, presenting a lower +LR value (WHO = 6·99/MULT 18 years = 10·99; 19 years = 8·99; 20 years = 8·09) for the same -LR values (0·04). Therefore, MULT reference holds promise as a valuable tool for diagnosing childhood obesity, particularly when considering sex differences. This enhances its suitability for assessing the nutritional status of Brazilian schoolchildren.