University of São Paulo: USP researcher develops new tool to diagnose child malnutrition

FORresearchers from USP’s Faculty of Public Health (FSP), in partnership with the University of Porto, in Portugal, developed a new height growth reference for age, based on longitudinal data from multi-ethnic populations in eight countries and two cities. Named MULT (multiethnic), this may be a new option available to assess the nutritional status of children and adolescents aged 0 to 20 years.

The results of the work, entitled A new height-for-age growth reference and its efficiency in the classification of the nutrition status of multiethnic children and adolescents , were compared with two references already adopted in clinical practice, proposed by the World Health Organization (WHO). ) and the Centers for Disease Control and Prevention (CDC) in the United States.

Height-for-age curves show the child’s growth trajectory and are considered the best overall indicator of child well-being, in addition to being a crucial tool for detecting nutritional risks. “However, some countries have developed their own growth curves because they consider that the existing international curves are not suitable for application in their countries”, explains Joana Araújo, researcher at the Research Group: Epidemiology of Nutrition and Obesity at the Universidad e Porto and co-author of the study. “With our results, we believe that the MULT reference may be another option available for health professionals to assess the nutritional status of multiethnic children and adolescents.”


Mariane Helen – Photo: Personal archive
The MULT curve showed a higher population, that is, boys with greater height between the ages of 5 to 14 years and 16.5 to 20 years, and girls with the same profile between the ages of 5 to 12 years and from 15 to 20 years, when compared to the WHO and CDC growth curves.

“This indicates that there was a secular growth trend, which is any change in body size in a given population group over long periods of time”, explains Mariane Helen de Oliveira, nutritionist and first author of the study. “Furthermore, the survey demonstrated greater agreement with the WHO growth benchmark, especially for children under 5 years of age.”

The 2-5 year age group had the closest prevalence of height deficit between growth curves, ranging from 7.07% to 7.97%, and there was an almost perfect agreement between the WHO and the MULT for this age group .


Coefficient of variation (S-curve) of the four growth references in boys and girls – Photo: Disclosure

For the study, anthropometric, demographic and socioeconomic data were selected from 17,600 multiethnic children and adolescents, under 20 years old, born between 1990 and 2002, from four longitudinal studies: Young Lives (YL), Millenium Cohort Study (MCS), Adolescent Nutritional Assessment Longitudinal Study Cohort (ELANA) and Epidemiological Investigation in Adolescent Health of Porto (EPI Teen).

Malnutrition: a global theme
Malnutrition is an important public health problem and affects around 149 million children under the age of five, according to data from the United Nations Fund for Children, Science and Culture (Unicef). It occurs mainly in low- and middle-income countries. Only in Africa and Asia there are, respectively, 59 and 82 million children with short stature, which means that about 94% of all children with these conditions live in these two continents.

Monitoring development and growth soon after birth is essential to predict nutritional and health risks. “If the diagnosis is made early, we are able to prevent diseases and other risks that may appear later”, emphasizes Mariane Helen de Oliveira.

Brazil managed to reduce the rate of chronic malnutrition among children under 5 from 19% in 1990 to 7% in 2006. But, according to the Ministry of Health, in 2018, chronic malnutrition among indigenous children under 5 years was 28.6%.

As a result, malnutrition causes reduced physical growth and lower intellectual performance in children. Therefore, monitoring development and growth soon after birth is essential to predict nutritional and health risks. “If the diagnosis is made early, we can prevent diseases and other risks that may appear later”, emphasizes Mariane.

The main tools used by pediatricians and health professionals to monitor the growth of individuals aged 0 to 20 years are anthropometry and the height-for-age growth chart, which shows how development takes place in a linear fashion.

Over the years, some organizations, such as the CDC and WHO, have proposed height-for-age growth references for use around the world. The CDC charts were developed in the 2000s, based only on the US population and using five national surveys conducted between the years 1963 and 1964.

The WHO indicators were produced in 2006 for children under 5 years of age and in 2007 for children and adolescents aged 5 to 19 years. For children under 5 years of age, growth charts were constructed based on cross-sectional and longitudinal samples of children considered to be standard (lactating, healthy, with good socioeconomic status to ensure adequate development) and multiethnic populations from six countries (Brazil, United States, Ghana, Norway, India and Oman). However, for the population aged 5 to 20 years, the constructions of the growth charts were based only on the cross-sectional study with a sample of the population of a unit in the United States: white, black, Hispanic and Asian-American children, born in the 1950s and 1960.

Several countries have questioned the application of WHO references, especially for children under 5 years of age. The European Commission on Nutrition and the Ministry of Health in Argentina, for example, recommend only using the WHO tables for children under 5 years of age, as data for different ethnic groups of that age are more consistent.

working with information
The article published by Mariane is part of the sandwich doctorate she is developing with the University of Porto. To start the work, the first step was to search for available databases. The researcher then selected four of them.

Young Lives is a 15-year study that seeks to understand the causes, dynamics and consequences of child poverty in four countries: Ethiopia, India, Peru and Vietnam. Provides data on 12,000 children from two cohorts (long-term follow-up), one younger (YLYC) with children born in the 2000s, and one older (YLOC) with those born in the 1990s. were assessed at 1, 5, 8, 12 and 15 years of age, while at YLOC participants were assessed at 8, 12, 15, 19 and 22 years of age.

The Millennium Cohort Study investigated around 19,000 babies born between 2000 and 2002 in the United Kingdom (England, Scotland, Wales and Northern Ireland). The survey provides multiple measures of the cohort members’ physical, socio-emotional, cognitive and behavioral development over time, as well as detailed information about their daily life, behavior and experiences. The study baseline began at 9 months of age and they reassessed children at 3, 5, 7, 11, 14 and 17 years of age.

The Adolescent Nutritional Assessment Longitudinal Study Cohort (ELANA) is a study of 1,848 adolescents from two cohorts, one from elementary school and the other from high school. These teenagers were born between 1990 and 2000 and came from four private and two public schools in Rio de Janeiro, Brazil. The group was evaluated a few times during the school term.

The EPITeen is a cohort study of nearly 3,000 teenagers born in the 1990s who attended public and private schools in the city of Porto, Portugal. The research began in 2003, when the teenagers were 13 years old. They were re-evaluated at 17, 21, 24 and 27 years old. In addition, anthropometric data, from birth and during childhood, were collected from their medical records.

With the data in hand, Mariane told Jornal da USP that, in the next step, a thorough filtering of the available data is carried out. “We need to assess whether there are measurement errors and missing information, for example, so that we can reach the total number of individuals able to participate in the work”, says Mariane. “We selected the richest quintile from our database and, in the end, we had 2,611 children and 15,299 eligible measures to construct the MULT curve.”


Dataset included in this study – Photo: Disclosure

Children were divided into four groups by age: 0 to <2 years, as at this age they are evaluated lying down; 2 to <5 years, for being analyzed standing and being in the period before puberty; 10 to <15 years, as it is the beginning of adolescence and, at this stage, physical changes begin, usually with a jump in growth, followed by the development of sexual organs and secondary sexual characteristics; and 15 to ≤ 20 years, because it is late adolescence and early adulthood.

With the most important data selected, the researchers start to design the models that will be applied in the new tool. Finally, the results are compared with WHO and CDC references.

MULT reference
The MULT reference showed taller boys between the ages of 5 to 14 years and 16.5 to 20 years, and girls with the same profile between the ages of 5 to 12 years and 15 to 20 years, when compared to the mean values height for age by WHO and CDC.


Average height (curve M) for the age of the four growth references in boys and girls – Photo: Disclosure

Using the CDC reference, there were more children and adolescents classified as short stature when compared to the WHO and MULT growth references. For the age group from 2 to 5 years, the growth references of the CDC, WHO and MULT showed very equivalent stunting prevalence, ranging between 7.07% and 7.97%.


Stunting prevalence by age group according to the three growth references – Photo: Disclosure

The study found substantial agreement between the MULT growth references for the entire sample and for most age groups, with the exception of 2 to 5 years old – this one showed almost perfect agreement.

The agreement between the WHO and CDC references was almost perfect for adolescents aged ten years and older, and was substantial among children under ten years of age.

More work
While still in her doctorate, Mariane intends to build another curve of the Body Mass Index (BMI) for age. “We are going to validate it through the percentage of fat existing in other databases”, he explains. “In the last phase, I will work with the growth channel, which is the amount, in centimeters, that a child must grow in a given period.”

For Louise Cominato, pediatrician at the Instituto da Criança of the Hospital das Clínicas, Faculty of Medicine of USP (FMUSP) and member of the Society of Pediatrics of São Paulo, the new curve needs to be tested in medical routine. “But since the WHO curve for a given age uses mathematical models, if the MULT curve was built using research data, it could be quite interesting.”

Joana believes that the difference lies in using the MULT curve for different populations, as it was built with a very heterogeneous sample.

Once ready, the researcher will make the new tools available to health professionals. “Clinical practice will show the accuracy of the MULT”, he concludes.

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